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A moderate space mission for optical interferometry
NASA Technical Reports Server (NTRS)
Gershman, R.; Rayman, M. D.; Shao, M.
The Orbiting Stellar Interferometer (OSI) is a proposed space-based observatory which will open exciting new vistas in astronomy and address fundamental scientific questions by making extremely accurate (3 - 30 microarcsecond) astrometric measurements of the positions of stars, quasars, and other astronomical objects as faint as magnitude 20. In addition, it will be able to image objects with a resolution of 5 milliarcseconds. As the first optical interferometer in space, OSI will provide major advances in astrophysics while demonstrating a powerful concept applicable to major space-based observations of the future. The Jet Propulsion Laboratory has developed a preliminary design of OSI to establish its feasibility and to estimate performance that can be achieved in a mission of moderate scale. In this first publication of the results of the first year of study, the science objectives are presented, and the design of the mission, instrument, and spacecraft are discussed.
The relation between Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth and PM2.5 over the United States: a geographical comparison by U.S. Environmental Protection Agency regions.
Zhang, Hai; Hoff, Raymond M; Engel-Cox, Jill A
Aerosol optical depth (AOD) acquired from satellite measurements demonstrates good correlation with particulate matter with diameters less than 2.5 microm (PM2.5) in some regions of the United States and has been used for monitoring and nowcasting air quality over the United States. This work investigates the relation between Moderate Resolution Imaging Spectroradiometer (MODIS) AOD and PM2.5 over the 10 U.S. Environmental Protection Agency (EPA)-defined geographic regions in the United States on the basis of a 2-yr (2005-2006) match-up dataset of MODIS AOD and hourly PM2.5 measurements. The AOD retrievals demonstrate a geographical and seasonal variation in their relation with PM2.5. Good correlations are mostly observed over the eastern United States in summer and fall. The southeastern United States has the highest correlation coefficients at more than 0.6. The southwestern United States has the lowest correlation coefficient of approximately 0.2. The seasonal regression relations derived for each region are used to estimate the PM2.5 from AOD retrievals, and it is shown that the estimation using this method is more accurate than that using a fixed ratio between PM2.5 and AOD. Two versions of AOD from Terra (v4.0.1 and v5.2.6) are also compared in terms of the inversion methods and screening algorithms. The v5.2.6 AOD retrievals demonstrate better correlation with PM2.5 than v4.0.1 retrievals, but they have much less coverage because of the differences in the cloud-screening algorithm.
Solid state optical microscope
Young, Ian T.
A solid state optical microscope wherein wide-field and high-resolution images of an object are produced at a rapid rate by utilizing conventional optics with a charge-coupled photodiode array. A galvanometer scanning mirror, for scanning in one of two orthogonal directions is provided, while the charge-coupled photodiode array scans in the other orthogonal direction. Illumination light from the object is incident upon the photodiodes, creating packets of electrons (signals) which are representative of the illuminated object. The signals are then processed, stored in a memory, and finally displayed as a video signal.
Solid state optical microscope
Young, I.T.
A solid state optical microscope wherein wide-field and high-resolution images of an object are produced at a rapid rate by utilizing conventional optics with a charge-coupled photodiode array. A galvanometer scanning mirror, for scanning in one of two orthogonal directions is provided, while the charge-coupled photodiode array scans in the other orthogonal direction. Illumination light from the object is incident upon the photodiodes, creating packets of electrons (signals) which are representative of the illuminated object. The signals are then processed, stored in a memory, and finally displayed as a video signal. 2 figs.
Moderate Cortical Cooling Eliminates Thalamocortical Silent States during Slow Oscillation.
Sheroziya, Maxim; Timofeev, Igor
Reduction in temperature depolarizes neurons by a partial closure of potassium channels but decreases the vesicle release probability within synapses. Compared with cooling, neuromodulators produce qualitatively similar effects on intrinsic neuronal properties and synapses in the cortex. We used this similarity of neuronal action in ketamine-xylazine-anesthetized mice and non-anesthetized mice to manipulate the thalamocortical activity. We recorded cortical electroencephalogram/local field potential (LFP) activity and intracellular activities from the somatosensory thalamus in control conditions, during cortical cooling and on rewarming. In the deeply anesthetized mice, moderate cortical cooling was characterized by reversible disruption of the thalamocortical slow-wave pattern rhythmicity and the appearance of fast LFP spikes, with frequencies ranging from 6 to 9 Hz. These LFP spikes were correlated with the rhythmic IPSP activities recorded within the thalamic ventral posterior medial neurons and with depolarizing events in the posterior nucleus neurons. Similar cooling of the cortex during light anesthesia rapidly and reversibly eliminated thalamocortical silent states and evoked thalamocortical persistent activity; conversely, mild heating increased thalamocortical slow-wave rhythmicity. In the non-anesthetized head-restrained mice, cooling also prevented the generation of thalamocortical silent states. We conclude that moderate cortical cooling might be used to manipulate slow-wave network activity and induce neuromodulator-independent transition to activated states. Significance statement: In this study, we demonstrate that moderate local cortical cooling of lightly anesthetized or naturally sleeping mice disrupts thalamocortical slow oscillation and induces the activated local field potential pattern. Mild heating has the opposite effect; it increases the rhythmicity of thalamocortical slow oscillation. Our results demonstrate that slow oscillation can be
Solid-state optical microscope
Young, I.T.
A solid state optical microscope is described wherein wide-field and high-resolution images of an object are produced at a rapid rate by utilizing conventional optics with a charge-coupled photodiode array. Means for scanning in one of two orthogonal directions are provided, while the charge-coupled photodiode array scans in the other orthogonal direction. Illumination light from the object is incident upon the photodiodes, creating packets of electrons (signals) which are representative of the illuminated object. The signals are then processed, stored in a memory, and finally displayed as a video signal.
Optically excited states in positronium
NASA Technical Reports Server (NTRS)
Howell, R. H.; Ziock, Klaus P.; Magnotta, F.; Dermer, Charles D.; Failor, R. A.; Jones, K. M.
Optical excitation are reported of the 1 3S-2 3P transition in positronium, and a second excitation from n=2 to higher n states. The experiment used light from two pulsed dye lasers. Changes in the positronium annihilation rate during and after the laser pulse were used to deduce the excited state populations. The n=2 level was found to be saturable and excitable to a substantial fraction of n=2 positronium to higher levels. Preliminary spectroscopic measurements were performed on n=14 and n=15 positronium.
Moderate chill peach variety development for the Southeastern United States
Technology Transfer Automated Retrieval System (TEKTRAN)
The Southeastern U.S. peach industry is concentrated in two production areas, i.e. Central Georgia/South Carolina (high chill, main season) and the Lower Coastal Plain (moderate chill, early season) along the Gulf coast. These two areas have distinctly different climates, and consequently, require ...
State of Ohio Curriculum Guide for Moderately Mentally Retarded Learners.
ERIC Educational Resources Information Center
Mays, Maxine.
Provided is a curriculum guide based on the lifelong learning needs of moderately retarded persons. Behavioral objectives are identified at each of six levels of functioning which approximate the mental age levels of 1.5, 3.0, 5.0, 7.0, 8.0, and 8.0 + (adult) years. Sections cover the following persisting life problem areas: (1) developing the…
Optical Scaling Relations of X-ray Selected Clusters at Moderate Redshift
NASA Astrophysics Data System (ADS)
Kloster, Dylan; Rines, K.; Svoboda, B. E.; Arnold, R. L.; Welch, T. J.; Finn, R. A.; Vikhlinin, A.
The relation between dark matter and galaxies is a fundamental problem in astrophysics. Here, we study this relation using optical observations of an X-ray-selected sample of clusters at moderate redshift (z=0.35-0.90). We collected griz images of 30 clusters with WIYN/OPTIC to measure the bright end of the luminosity function. Our imaging extends approximately 2 magnitudes fainter than M*, thus including most of the total cluster light. We use the red sequence and statistical background subtraction to estimate the richnesses and stellar luminosities of the clusters. We measure scaling relations by comparing the optical properties to X-ray mass estimates derived from Chandra observations. At low redshift, some studies indicate that total stellar luminosity is a better predictor of cluster mass than X-ray luminosity. We test whether a similar result holds at moderate redshift. In the future, we will compare the optical and X-ray properties to virial mass estimates from optical spectroscopy and to Sunyaev-Zeldovich Effect observations. If photometric properties of clusters are good predictors of cluster mass, these relations could be applied to large surveys like SPT, Planck, DES, eROSITA, and LSST to improve constraints on the properties of dark energy.
Moderating effects of music on resting state networks.
Kay, Benjamin P; Meng, Xiangxiang; Difrancesco, Mark W; Holland, Scott K; Szaflarski, Jerzy P
Resting state networks (RSNs) are spontaneous, synchronous, low-frequency oscillations observed in the brains of subjects who are awake but at rest. A particular RSN called the default mode network (DMN) has been shown to exhibit changes associated with neurological disorders such as temporal lobe epilepsy or Alzheimer's disease. Previous studies have also found that differing experimental conditions such as eyes-open versus eyes-closed can produce measurable changes in the DMN. These condition-associated changes have the potential of confounding the measurements of changes in RSNs related to or caused by disease state(s). In this study, we use fMRI measurements of resting-state connectivity paired with EEG measurements of alpha rhythm and employ independent component analysis, undirected graphs of partial spectral coherence, and spatiotemporal regression to investigate the effect of music-listening on RSNs and the DMN in particular. We observed similar patterns of DMN connectivity in subjects who were listening to music compared with those who were not, with a trend toward a more introspective pattern of resting-state connectivity during music-listening. We conclude that music-listening is a valid condition under which the DMN can be studied.
Sequential quantum teleportation of optical coherent states
Yonezawa, Hidehiro; Furusawa, Akira; Loock, Peter van
We demonstrate a sequence of two quantum teleportations of optical coherent states, combining two high-fidelity teleporters for continuous variables. In our experiment, the individual teleportation fidelities are evaluated as F{sub 1}=0.70{+-}0.02 and F{sub 2}=0.75{+-}0.02, while the fidelity between the input and the sequentially teleported states is determined as F{sup (2)}=0.57{+-}0.02. This still exceeds the optimal fidelity of one half for classical teleportation of arbitrary coherent states and almost attains the value of the first (unsequential) quantum teleportation experiment with optical coherent states.
Optical coherence tomography and low-frequency mechanics: A moderated discussion
Freeman, Dennis M.; Ruggero, Mario A.
The following is an edited transcript of a recorded discussion session on the topics of "Optical Coherence Tomography" and "Low-Frequency Mechanics". The discussion, moderated by the authors, took place at the 12{sup th} International Workshop on the Mechanics of Hearing held at Cape Sounio, Greece, in June 2014. All participants knew that the session was being recorded. In view of both the spontaneous nature of the discussion and the editing, however, this transcript may not represent the considered or final views of the participants, and may not represent a consensus of experts in the field. The reader is advised to consult additional independent publications.
Moderate plasma treatment enhances the quality of optically detected magnetic resonance signals of nitrogen-vacancy centres in nanodiamonds
NASA Astrophysics Data System (ADS)
Sotoma, Shingo; Igarashi, Ryuji; Shirakawa, Masahiro
We demonstrate that a moderate plasma treatment increases the quality of optically detected magnetic resonance (ODMR) signals from negatively charged nitrogen-vacancy centres in nanodiamonds (NDs). We measured the statistics of the ODMR spectra of 50-nm-size NDs before and after plasma treatment. We then evaluated each ODMR spectrum in terms of fluorescence and ODMR intensities, line width and signal-to-noise (SN) ratio. Our results showed that plasma treatment for more than 10 min contributes to higher-quality ODMR signals, i.e. signals that are brighter, stronger, sharper and have a higher SN ratio. We showed that such signal improvement is due to alteration of the surface chemical states of the NDs by the plasma treatment. Our study contributes to the advancement of biosensing applications using ODMR of NDs.
Global aerosol optical properties and application to Moderate Resolution Imaging Spectroradiometer aerosol retrieval over land
NASA Astrophysics Data System (ADS)
Levy, Robert C.; Remer, Lorraine A.; Dubovik, Oleg
As more information about global aerosol properties has become available from remotely sensed retrievals and in situ measurements, it is prudent to evaluate this new information, both on its own and in the context of satellite retrieval algorithms. Using the climatology of almucantur retrievals from global Aerosol Robotic Network (AERONET) Sun photometer sites, we perform cluster analysis to determine aerosol type as a function of location and season. We find that three spherical-derived types (describing fine-sized dominated aerosol) and one spheroid-derived types (describing coarse-sized dominated aerosol, presumably dust) generally describe the range of AERONET observed global aerosol properties. The fine-dominated types are separated mainly by their single scattering albedo (ω0), ranging from nonabsorbing aerosol (ω0 ˜ 0.95) in developed urban/industrial regions, to moderately absorbing aerosol (ω0 ˜ 0.90) in forest fire burning and developing industrial regions, to absorbing aerosol (ω0 ˜ 0.85) in regions of savanna/grassland burning. We identify the dominant aerosol type at each site, and extrapolate to create seasonal 1° × 1° maps of expected aerosol types. Each aerosol type is bilognormal, with dynamic (function of optical depth) size parameters (radius, standard deviation, volume distribution) and complex refractive index. Not only are these parameters interesting in their own right, they can also be applied to aerosol retrieval algorithms, such as to aerosol retrieval over land from Moderate Resolution Imaging Spectroradiometer. Independent direct-Sun AERONET observations of spectral aerosol optical depth (τ) are consistent the spectral dependence of the models, indicating that our derived aerosol models are relevant.
Arbitrary unitary transformations on optical states using a quantum memory
Campbell, Geoff T.; Pinel, Olivier; Hosseini, Mahdi; Buchler, Ben C.; Lam, Ping Koy
We show that optical memories arranged along an optical path can perform arbitrary unitary transformations on frequency domain optical states. The protocol offers favourable scaling and can be used with any quantum memory that uses an off-resonant Raman transition to reversibly transfer optical information to an atomic spin coherence.
Efficient quantum optical state engineering and applications
NASA Astrophysics Data System (ADS)
McCusker, Kevin T.
Over a century after the modern prediction of the existence of individual particles of light by Albert Einstein, a reliable source of this simple quantum state of one photon does not exist. While common light sources such as a light bulb, LED, or laser can produce a pulse of light with an average of one photon, there is (currently) no way of knowing the number of photons in that pulse without first absorbing (and thereby destroying) them. Spontaneous parametric down-conversion, a process in which one high-energy photon splits into two lower-energy photons, allows us to prepare a single-photon state by detecting one of the photons, which then heralds the existence of its twin. This process has been the workhorse of quantum optics, allowing demonstrations of a myriad of quantum processes and protocols, such as entanglement, cryptography, superdense coding, teleportation, and simple quantum computing demonstrations. All of these processes would benefit from better engineering of the underlying down-conversion process, but despite significant effort (both theoretical and experimental), optimization of this process is ongoing. The focus of this work is to optimize certain aspects of a down-conversion source, and then use this tool in novel experiments not otherwise feasible. Specifically, the goal is to optimize the heralding efficiency of the down-conversion photons, i.e., the probability that if one photon is detected, the other photon is also detected. This source is then applied to two experiments (a single-photon source, and a quantum cryptography implementation), and the detailed theory of an additional application (a source of Fock states and path-entangled states, called N00N states) is discussed, along with some other possible applications.
Positive affective states and alcohol consumption: The moderating role of trait positive urgency.
Dinc, Linda; Cooper, Andrew J
Trait positive urgency is characterised by risky and maladaptive actions in response to extreme positive affective states. Positive urgency has previously been shown to be a risk factor for alcohol consumption and alcohol-related problems; however, there has been limited experimental research examining how positive urgency may moderate relations between affective states and alcohol consumption. In the current study, a sample of 106 participants completed a trait measure of positive urgency and were then randomly assigned to one of three mood induction conditions: a high-activation positive, a low-activation positive or a neutral mood condition. Subsequently, participants took part in a bogus beer taste test, where their alcohol consumption was subsequently measured. The results revealed that positive urgency significantly predicted increased beer consumption, but only for those participants in the high-activation positive mood induction group. The findings from this study provide support for positive urgency as a risk factor for alcohol use and suggest that it may be of particular relevance in social situations where individuals experience highly activated positive affective states.
Self-awareness moderates the relation between maternal mental state language about desires and children's mental state vocabulary.
Taumoepeau, Mele; Ruffman, Ted
In this intervention study, we tested the differential effect of talking about children's desires versus talking about others' thoughts and knowledge on children's acquisition of mental state vocabulary for children who did and did not have mirror self-recognition. In a sample of 96 mother-toddler dyads, each mother was randomly assigned a specially constructed, interactive lift-the-flap book to read to her child three times a week for 4 weeks. In the child desire condition the story elicited comments regarding the child's desires, and in the cognitive condition the story elicited the mother's comments about her own thoughts and knowledge while reading the story. Children's mirror self-recognition and mental state vocabulary were assessed at pre- and post-test. Children in the condition that focused on the child's desires showed a significantly greater increase in their mental state vocabulary; however, this effect was moderated by their levels of self-awareness, with children benefitting more from the intervention if they also showed self-recognition at pre-test. We argue that the combination of specific types of maternal talk and children's prior insights facilitates gains in children's mental state vocabulary.
Altered Resting State Cortico-Striatal Connectivity in Mild to Moderate Stage Parkinson's Disease
Kwak, Youngbin; Peltier, Scott; Bohnen, Nicolaas I.; Müller, Martijn L. T. M.; Dayalu, Praveen; Seidler, Rachael D.
Parkinson's disease (PD) is a progressive neurodegenerative disorder that is characterized by dopamine depletion in the striatum. One consistent pathophysiological hallmark of PD is an increase in spontaneous oscillatory activity in the basal ganglia thalamocortical networks. We evaluated these effects using resting state functional connectivity MRI in mild to moderate stage Parkinson's patients on and off l-DOPA and age-matched controls using six different striatal seed regions. We observed an overall increase in the strength of cortico-striatal functional connectivity in PD patients off l-DOPA compared to controls. This enhanced connectivity was down-regulated by l-DOPA as shown by an overall decrease in connectivity strength, particularly within motor cortical regions. We also performed a frequency content analysis of the BOLD signal time course extracted from the six striatal seed regions. PD off l-DOPA exhibited increased power in the frequency band 0.02–0.05 Hz compared to controls and to PD on l-DOPA. The l-DOPA associated decrease in the power of this frequency range modulated the l-DOPA associated decrease in connectivity strength between striatal seeds and the thalamus. In addition, the l-DOPA associated decrease in power in this frequency band correlated with the l-DOPA associated improvement in cognitive performance. Our results demonstrate that PD and l-DOPA modulate striatal resting state BOLD signal oscillations and cortico-striatal network coherence. PMID:21206528
Effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjects
Background Eurycoma longifolia is a medicinal plant commonly called tongkat ali (TA) and "Malaysian ginseng." TA roots are a traditional "anti-aging" remedy and modern supplements are intended to improve libido, energy, sports performance and weight loss. Previous studies have shown properly-standardized TA to stimulate release of free testosterone, improve sex drive, reduce fatigue, and improve well-being. Methods We assessed stress hormones and mood state in 63 subjects (32 men and 31 women) screened for moderate stress and supplemented with a standardized hot-water extract of TA root (TA) or Placebo (PL) for 4 weeks. Analysis of variance (ANOVA) with significance set at p < 0.05 was used to determine differences between groups. Results Significant improvements were found in the TA group for Tension (−11%), Anger (−12%), and Confusion (−15%). Stress hormone profile (salivary cortisol and testosterone) was significantly improved by TA supplementation, with reduced cortisol exposure (−16%) and increased testosterone status (+37%). Conclusion These results indicate that daily supplementation with tongkat ali root extract improves stress hormone profile and certain mood state parameters, suggesting that this "ancient" remedy may be an effective approach to shielding the body from the detrimental effects of "modern" chronic stress, which may include general day-to-day stress, as well as the stress of dieting, sleep deprivation, and exercise training. PMID:23705671
Use of Optical Fiber Imported Intra-Tissue Photodynamic Therapy for Treatment of Moderate to Severe Acne Vulgaris
Wang, Qian; Yuan, Dan; Liu, Wei; Chen, Jin; Lin, Xinyu; Cheng, Shi; Li, Fumin; Duan, Xiling
Background To treat moderate to severe acne vulgaris, we developed an optical fiber imported intra-tissue photodynamic therapy: the optical fiber irradiation 5-aminolevulinic acid photodynamic therapy (OFI-ALA-PDT). The aim of this study was to compare the treatment effect and tolerability of OFI-ALA-PDT versus traditional ALA-PDT in the treatment of moderate to severe acne vulgaris. Material/Methods 60 patients with facial acne enrolled into this study were randomly divided into an OFI-ALA-PDT group and a traditional ALA-PDT group, with 30 patients in each group. The difference between these 2 groups was the red light irradiation methods used. In the OFI-ALA-PDT group we used intra-tissue irradiation (import the red light directly into the target lesion with optical fiber) for 5 min, while the traditional ALA-PDT group received whole-face irradiation for 20 min. All patients received 1 irradiation every 7 to 10 days for a total of 6 irradiations. Treatment effects and adverse reactions were recorded after the 4th and 6th irradiation, and at 4, 8, 16 weeks after the entire treatment. Results After the 4th irradiation, significantly different effective rates were observed in these groups (90.0% for the OFI-ALA-PDT group and 66.7% for the control group). However, no significant difference in effective rate was recorded in the later observations. There were 182 adverse reactions in the OFI-ALA-PDT group and 497 in the control group, which showed a significant difference (P<0.05). Conclusions OFI-ALA-PDT showed improved treatment effective rate in the early stage of irradiation, and it had fewer adverse reactions. PMID:26839152
Optical glass: standards - present state and outlook
NASA Astrophysics Data System (ADS)
Hartmann, Peter
In 1996, the international organization for standardization ISO started the standards series ISO 10110 specifying indications in drawings of optical elements. Three parts cover material properties: part 2 (stress birefringence), 3 (bubbles and inclusions), and 4 (inhomogeneity and striae). Customers used to just send optical element drawings to glass manufacturers often leading to uncertainty, overspecification, and delivery problems. The raw glass standard ISO 12123 of 2010 allows direct addressing of raw glass specifications. Harmonizing ISO 10110 with ISO 12123 and progress in inspection methods require updating of the material specifying parts. A new part 18 containing all properties is under preparation and is meant to replace parts 2-4. ISO 12123 will be amended by introducing definitions for relative partial dispersions and reference normal lines and grade denominations for tolerance ranges. The working draft ISO/WD 10110 part 18 extends indication possibilities to allow relating to ISO 12123 while ensuring backward compatibility. Default optical glass quality and direct specification of raw glass simplify tolerancing considerably. Annexes support selection of appropriate quality classes referring to optical element size categories. Test and inspection standards on chemical resistances, hardness, stress birefringence, and optical homogeneity will be maintained. Standards for water resistance, refractive index, and striae inspection are being prepared.
Solid state electro-optic color filter and iris
NASA Technical Reports Server (NTRS)
Test results obtained have confirmed the practicality of the solid state electro-optic filters as an optical control element in a television system. Neutral-density control range in excess of 1000:1 has been obtained on sample filters. Test results, measurements in a complete camera system, discussions of problem areas, analytical comparisons, and recommendations for future investigations are included.
Optical Flow-Based State Estimation for Guided Projectiles
ARL-TR-7321 ● JUNE 2015 US Army Research Laboratory Optical Flow-Based State Estimation for Guided Projectiles by Moshe... Guided Projectiles by Moshe Hamaoui Weapons and Materials Research Directorate, ARL Approved for public release...
Multimode optical fibers: steady state mode exciter.
Ikeda, M; Sugimura, A; Ikegami, T
The steady state mode power distribution of the multimode graded index fiber was measured. A simple and effective steady state mode exciter was fabricated by an etching technique. Its insertion loss was 0.5 dB for an injection laser. Deviation in transmission characteristics of multimode graded index fibers can be avoided by using the steady state mode exciter.
State of the Art Review: Optical Processing.
lenses, optical fibers , or planar lightguides to illuminate a two-dimensional mask that represents the matrix A. Light from the mask that has been... polybenzobisoxazole 7. Polyester and polyesteramids 8. Polyetherketone 9. Polyquinoxalines 10. Porphyrins and metal-porphyrin complexes 11. Metal complexes of
Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis
Technology Transfer Automated Retrieval System (TEKTRAN)
BACKGROUND: The effects of essential amino acid (EAA) supplementation during moderate steady state (ie, endurance) exercise on postexercise skeletal muscle metabolism are not well described, and the potential role of supplemental leucine on muscle protein synthesis (MPS) and associated molecular re...
Optical state-of-charge monitor for batteries
Weiss, Jonathan D.
A method and apparatus for determining the instantaneous state-of-charge of a battery in which change in composition with discharge manifests itself as a change in optical absorption. In a lead-acid battery, the sensor comprises a fiber optic system with an absorption cell or, alternatively, an optical fiber woven into an absorbed-glass-mat battery. In a lithium-ion battery, the sensor comprises fiber optics for introducing light into the anode to monitor absorption when lithium ions are introduced.
Moderate repetition rate ultra-intense laser targets and optics using variable thickness liquid crystal films
NASA Astrophysics Data System (ADS)
Poole, P. L.; Willis, C.; Cochran, G. E.; Hanna, R. T.; Andereck, C. D.; Schumacher, D. W.
Liquid crystal films are variable thickness, planar targets for ultra-intense laser matter experiments such as ion acceleration. Their target qualities also make them ideal for high-power laser optics such as plasma mirrors and waveplates. By controlling parameters of film formation, thickness can be varied on-demand from 10 nm to above 50 μm, enabling real-time optimization of laser interactions. Presented here are results using a device that draws films from a bulk liquid crystal source volume with any thickness in the aforementioned range. Films form within 2 μm of the same location each time, well within the Rayleigh range of even tight F / # systems, thus removing the necessity for realignment between shots. The repetition rate of the device exceeds 0.1 Hz for sub-100 nm films, facilitating higher repetition rate operation of modern laser facilities.
Moderate repetition rate ultra-intense laser targets and optics using variable thickness liquid crystal films
Poole, P. L.; Willis, C.; Cochran, G. E.; ...
Liquid crystal films are variable thickness, planar targets for ultra-intense laser matter experiments such as ion acceleration. Their target qualities also make them ideal for high-power laser optics such as plasma mirrors and waveplates. By controlling parameters of film formation, thickness can be varied on-demand from 10 nm to above 50 μm, enabling real-time optimization of laser interactions. Presented here are results using a device that draws films from a bulk liquid crystal source volume with any thickness in the aforementioned range. Films form within 2 μm of the same location each time, well within the Rayleigh range of evenmore » tight F/# systems, thus removing the necessity for realignment between shots. As a result, the repetition rate of the device exceeds 0.1 Hz for sub-100nm films, facilitating higher repetition rate operation of modern laser facilities.« less
Moderate repetition rate ultra-intense laser targets and optics using variable thickness liquid crystal films
Poole, P. L.; Willis, C.; Cochran, G. E.; Hanna, R. T.; Andereck, C. D.; Schumacher, D. W.
Liquid crystal films are variable thickness, planar targets for ultra-intense laser matter experiments such as ion acceleration. Their target qualities also make them ideal for high-power laser optics such as plasma mirrors and waveplates. By controlling parameters of film formation, thickness can be varied on-demand from 10 nm to above 50 μm, enabling real-time optimization of laser interactions. Presented here are results using a device that draws films from a bulk liquid crystal source volume with any thickness in the aforementioned range. Films form within 2 μm of the same location each time, well within the Rayleigh range of even tight F/# systems, thus removing the necessity for realignment between shots. As a result, the repetition rate of the device exceeds 0.1 Hz for sub-100nm films, facilitating higher repetition rate operation of modern laser facilities.
Optical nanoscopy with excited state saturation at liquid helium temperatures
NASA Astrophysics Data System (ADS)
Yang, B.; Trebbia, J.-B.; Baby, R.; Tamarat, Ph.; Lounis, B.
Optical resolution of solid-state single quantum emitters at the nanometre scale is a challenging step towards the control of delocalized states formed by strongly and coherently interacting emitters. We have developed a simple super-resolution optical microscopy method operating at cryogenic temperatures, which is based on optical saturation of the excited state of single fluorescent molecules with a doughnut-shaped beam. Sub-10 nm resolution is achieved with extremely low excitation intensities, a million times lower than those used in room-temperature stimulated emission depletion microscopy. Compared with super-localization approaches, our technique offers a unique opportunity to super-resolve single molecules with overlapping optical resonance frequencies and paves the way to the study of coherent interactions between single emitters and to the manipulation of their degree of entanglement.
Laser action by optically depumping lower states
Krupke, William F.
A method and apparatus for obtaining laser action between an upper energy level and a lower energy level of a gaseous medium, which comprises populating the upper energy level to some degree (short of achieving a conventional inverted population) by any suitable pumping means, and thereafter establishing an inverted population by transiently and selectively depumping the lower energy level such as by exposing the medium to an intense source of radiation which selectively causes the transformation of the lower energy level species to some other energy level. Thus, a thermally pumped/optically depumped gas laser system is produced.
Laser action by optically depumping lower states
Krupke, W.F.
A method and apparatus are described for obtaining laser action between an upper energy level and a lower energy level of a gaseous medium. The upper energy level is populated to some degree (short of achieving a conventional inverted population) by any suitable pumping means, and an inverted population is established by transiently and selectively depumping the lower energy level. The depumping may be done by exposing the medium to an intense source of radiation which selectively causes the transformation of the lower energy level species to some other energy level. Thus, a thermally pumped/optically depumped gas laser system is produced.
Nonadditive Mixed State Phases in Neutron Optics
Klepp, J.; Sponar, S.; Filipp, S.; Lettner, M.; Badurek, G.; Hasegawa, Y.
In a neutron polarimetry experiment mixed neutron spin phases are determined. We consider evolutions leading to purely geometric, purely dynamical and combined phases. It is experimentally demonstrated that the sum of the geometric and dynamical phases--both obtained in separate measurements--is not equal to the associated total phase as obtained from a third measurement, unless the system is in a pure state. In this sense, mixed state phases are not additive.
Visual and optical performance of silicone hydrogel contact lenses for moderate myopia
Keir, Nancy; Simpson, Trefford; Fonn, Desmond
Purpose To compare the short-term visual and optical performance of silicone hydrogel contact lenses for myopia ≥ −3.00D. Methods This was a short-term, non-dispense, double-masked, randomized study investigating Night&Day (ND), PureVision (PV), O2 Optix (O2), Biofinity (BF), Acuvue Advance (AA) and Acuvue OASYS for myopia ≥ −3.00D. Testing was conducted under scotopic conditions. Measures (one eye only) included: high- and low-contrast visual acuity (HCVA/LCVA), contrast sensitivity, subjective clarity of vision ratings (0-100 scale using reference images, with test image representing grade 50) and ocular aberrations (up to the 4th order, analyzed across individual scotopic pupil sizes). Results Three males and 27 females participated, with a mean (± SD) age of 24.9 ± 7.7 yrs (range 19 to 53 yrs), sphere of −5.30 ± 1.73D (range −3.00 to −10.75D) and cylinder −0.36 ± 0.23D (range 0 to −0.75D). Mean (± SEM) logMAR HCVA ranged from 0.06 (PV) to 0.10 (AA) (± 0.02), LCVA from 0.33 (BF) to 0.40 (AA) (± 0.02) and contrast sensitivity from 2.33 (BF) to 2.53 (ND) (± 0.15) (differences not statistically significant; all p > 0.05). Subjective ratings for the test image ranged from 59 (PV) to 64 (ND) (± 4) and 56 (AA) to 65 (ND) (± 4), for monochromatic and polychromatic reference images, respectively (all p > 0.05). There was a statistically significant impact on ocular aberrations with all study lenses compared to no lens. Between-lens differences were statistically significant for defocus (Z02), horizontal coma (Z 13) and spherical aberration (Z04). Conclusions Despite some differences in ocular aberrations, there were no significant differences in HCVA, LCVA, contrast sensitivity or subjective ratings across lenses.
Teacher Preparation in Moderate and Severe Disabilities: A State Tool for Intern Support
ERIC Educational Resources Information Center
Whetstone, Patti; Abell, Michael; Collins, Belva C.; Kleinert, Harold L.
Teachers of students with moderate and severe disabilities must possess the skills and knowledge to address a unique set of needs and challenges. These may include, but are not limited to, management of challenging behaviors, performance of health-related procedures, use of assistive technology, and instruction using evidence-based strategies.…
Spatial distribution of dust's optical properties over the Sahara and Asia inferred from Moderate Resolution Imaging Spectroradiometer
NASA Astrophysics Data System (ADS)
Yoshida, M.; Haywood, J. M.; Johnson, B. T.; Murakami, H.; Nakajima, T.
There is a great deal of uncertainty surrounding the role of mineral dust aerosols in the earth's climate system. One reason for this uncertainty is that the optical properties of mineral dust, such as its single scattering albedo (the ratio of scattering to total extinction), are poorly understood because ground observations are limited to several locations and the satellite standard products are not available due to the excessively bright surface of the desert in the visible wavelength. We develop a method in this paper to estimate the spatial distributions of the aerosol single scattering albedo (ω0) and optical depth (τa), with daily 1 degree latitude and 1 degree longitude resolution, using data from Moderate Resolution Imaging Spectroradiometer (MODIS), as well as model simulations of radiative transfer. This approach is based on the "critical surface reflectance" method developed in the literature, which estimates ω0 from the top of the atmospheric radiance. We confirm that the uncertainties in our estimation of ω0 and τa are suitably minor and that the characteristic spatial distributions estimated over the Sahara and Asia are significant. The results for the Sahara indicate good correlation between ω0 and the surface reflectance and between ω0 and τa. Therefore, ω0 is determined mainly by the mineral composition of surface dust and/or the optical depth of airborne dust in the Sahara. On the other hand, the relationships between ω0, τa, and the surface reflectance are less clear in Asia than in the Sahara, and the values of ω0 are smaller than those in the Sahara. The regions with small ω0 values are consistent with the regions where coal-burning smoke and carbonaceous aerosols are thought to be transported, as reported in previous studies. Because the coal-burning and carbonaceous aerosols are known to be more absorptive and have smaller ω0 values than dust aerosols, our results indicate that the dust aerosols in Asia are contaminated by
Optical limiting and picosecond relaxation of carbocyanines upper electronic states
NASA Astrophysics Data System (ADS)
Oulianov, D. A.; Dvornikov, A. S.; Rentzepis, P. M.
Nonlinear absorption, anomalous fluorescence and relaxation of high-lying electronic states in six carbocyanine dyes, including cryptocyanine (DCI), DDI, DTDCI, DTTCI, DOTCI and HDIDCI, in solution and in polymer, were studied by means of picosecond transient absorption spectroscopy and nonlinear transmission experiments. Absorption cross-sections of the S 1→S n transition, and decay rates of the second singlet excited state, S 2, were measured. All dyes showed strong reverse saturable absorption in the 450-600 nm region with large excited to ground state absorption cross-section ratios. For DTDCI this ratio, at 470 nm, was measured to be 350, which is the largest ever reported. All molecules have shown strong optical limiting effect. However, in all molecules except DCI a saturation of the optical limiting process was observed as expected, owing to relatively long, up to 17.5 ps, lifetime of the S 2 state. The S 2 state fluorescence quantum yields were also measured.
Quantum state transfer through time reversal of an optical channel
NASA Astrophysics Data System (ADS)
Hush, M. R.; Bentley, C. D. B.; Ahlefeldt, R. L.; James, M. R.; Sellars, M. J.; Ugrinovskii, V.
Rare-earth ions have exceptionally long coherence times, making them an excellent candidate for quantum information processing. A key part of this processing is quantum state transfer. We show that perfect state transfer can be achieved by time reversing the intermediate quantum channel, and suggest using a gradient echo memory (GEM) to perform this time reversal. We propose an experiment with rare-earth ions to verify these predictions, where an emitter and receiver crystal are connected with an optical channel passed through a GEM. We investigate the effect experimental imperfections and collective dynamics have on the state transfer process. We demonstrate that super-radiant effects can enhance coupling into the optical channel and improve the transfer fidelity. We lastly discuss how our results apply to state transfer of entangled states.
New, Efficient Optically Pumped Solid State Lasers.
Lasers", during the contract period from 15 August 1984 thru 11 November 1988 (AFOSR-88-0378) has led to some notable advances. This effort h,.s focused...lower laser states of both Er and 1Ho. This work has led to the inves t igation of the Nd,Er ion-ion interactions in other crystals such as Nd,Er:YALO...backed pyrex reflector. While the laser may work in a gold-plated cavity, the many visible, blue and near uv pump bands suggest better efficiency is
Socioeconomic position and lower dietary moderation among Chinese immigrant women in the United States
Tseng, Marilyn; Fang, Carolyn Y.
Objective To examine associations of education and occupation, as indicators of socioeconomic position (SEP), with dietary intake and diet quality in a sample of Chinese immigrant women. Design Cross-sectional. Data collection included four days of dietary recalls and information on education and current occupation for participants and their spouses. Setting Philadelphia, PA, USA. Subjects 423 Chinese immigrant women recruited 10/05-4/08. Results In multivariate models, both higher education level and occupation category were significantly associated with higher energy density and intake of energy and sugar. Education was additionally associated with intake of sugar-sweetened beverages (p=0.01) and lower dietary moderation (p=0.01). With joint categorization based on both education and occupation, we observed significant trends indicating higher energy density (p=0.004) and higher intake of energy (p=0.001) and sugar (p=0.04), but less dietary moderation (p=0.02) with higher SEP. Conclusions In this sample of US Chinese immigrants, higher SEP as indicated by education level and occupation category was associated with differences in dietary intake, and with less dietary moderation. While higher SEP is typically linked to healthier diet in higher income nations, in these immigrants the association of SEP with diet follows the pattern of their country of origin – a lower-income country undergoing the nutrition transition. PMID:21806866
Effects of Moderate Aerobic Exercise on Cognitive Abilities and Redox State Biomarkers in Older Adults
Al-Eisa, Einas S.
We used a moderate aerobic exercise program for 24 weeks to measure the positive impact of physical activity on oxidative stress and inflammatory markers and its association with cognitive performance in healthy older adults. A total of 100 healthy subjects (65–95 Yrs) were randomly classified into two groups: control group (n = 50) and exercise group (n = 50). Cognitive functioning, physical activity score, MDA, 8-OHdG, TAC, and hs-CRP were assessed using LOTCA battery, prevalidated PA questionnaire, and immunoassay techniques. LOTCA 7-set scores of cognitive performance showed a significant correlation with physical activity status and the regulation of both oxidative stress free radicals and inflammatory markers in all older subjects following 24 weeks of moderate exercise. Physically active persons showed a higher cognitive performance along with reduction in the levels of MDA, 8-OHdG, and hs-CRP and increase in TAC activity compared with sedentary participants. Cognitive performance correlated positively with the increase in TAC activity and physical fitness scores and negatively with MDA, 8-OHdG, and hs-CRP, respectively. There was a significant improvement in motor praxis, vasomotor organization, thinking operations, and attention and concentration among older adults. In conclusion, moderate aerobic training for 24 weeks has a positive significant effect in improving cognitive functions via modulating redox and inflammatory status of older adults. PMID:27195073
Subwavelength optical lattices induced by position-dependent dark states
Sun Qingqing; Evers, Joerg; Kiffner, Martin; Zubairy, M. Suhail
A method for the generation of subwavelength optical lattices based on multilevel dark states is proposed. The dark state is formed by a suitable combination of standing wave light fields, leading to position-dependent populations of the ground states. An additional field coupling dispersively to one of the ground states translates this position dependence into a subwavelength optical potential. We provide two semiclassical approaches to understand the involved physics, and demonstrate that they lead to identical results in a certain meaningful limit. Then we apply a Monte Carlo simulation technique to study the full quantum dynamics of the subwavelength trapping. Finally, we discuss the relevant time scales for the trapping, optimum conditions, and possible implementations.
Fault tolerance in parity-state linear optical quantum computing
Hayes, A. J. F.; Ralph, T. C.; Haselgrove, H. L.; Gilchrist, Alexei
We use a combination of analytical and numerical techniques to calculate the noise threshold and resource requirements for a linear optical quantum computing scheme based on parity-state encoding. Parity-state encoding is used at the lowest level of code concatenation in order to efficiently correct errors arising from the inherent nondeterminism of two-qubit linear-optical gates. When combined with teleported error-correction (using either a Steane or Golay code) at higher levels of concatenation, the parity-state scheme is found to achieve a saving of approximately three orders of magnitude in resources when compared to the cluster state scheme, at a cost of a somewhat reduced noise threshold.
United States Atlas of Optical Telescopes. [2nd Edition
NASA Technical Reports Server (NTRS)
Meszaros, Stephen Paul
This atlas shows the locations of and gives information about optical telescopes used for astronomical research in the United States as of late 1986. Those instruments with mirror or lens diameters of 3/4 m (approx. 30 inches) and larger are included. These telescopes are concentrated in the Southwest, on the West Coast and on the island of Hawaii.
A new method to infer ozone column amounts and cloud optical depth from moderate bandwidth filter instruments
NASA Astrophysics Data System (ADS)
Fan, Lingling
This study presents a new method based on a radial basis functions neural network (RBF-NN) approach to analyze data from moderate bandwidth filter instruments such as the NILU-UV Irradiance Meter. The NILU-UV Irradiance Meter is a ground-based, multi-channel, moderate bandwidth filter instrument that measures irradiances at ultraviolet (UV) and visible wavelengths with five channels in the UV (302, 312, 320, 340 and 380 nm) and one channel in the visible (400-700 nm) part of the spectrum. Minute-by-minute irradiances recorded by the instruments are used to infer the total ozone column (TOC) amount, and a radiation modification factor (RMF), which represents the combined effect of clouds, aerosols and surface reflection. We used a cloud optical depth (COD) as a proxy for the RMF. Traditionally, these parameters are retrieved by using a look up table (LUT) method, which relates TOC and RMF values to UV irradiances recorded by the NILU-UV instrument. In this study we use a neural network available in Matlab. A radiative transfer model is used to compute irradiances in the NILU-UV channels (output parameters) as a function of 3 input parameters consisting of (i) the solar zenith angle, (ii) the TOC amount, and (iii) the COD. The resulting model data set is used in the neural network to create a relationship between the input and output parameters in terms of a set of coefficients. By applying the RBF-NN method to about 3 years of data from NILU-UV instruments deployed in the New York area, we found that compared to the LUT method, the results of the RBF-NN method had better agreement with TOC values inferred from satellite data with an increase of 3% in the correlation. Furthermore, the RBF-NN method retrieved more valid results than the LUT method. In addition, we discuss retrieved results, such as RMF, CIE weighted UV index (UVI), TOC from 3 NILU-UV instruments, and compare the TOC and UVI values derived from NILU-UV instruments with the corresponding values inferred
Loss-resilient photonic entanglement swapping using optical hybrid states
NASA Astrophysics Data System (ADS)
Lim, Youngrong; Joo, Jaewoo; Spiller, Timothy P.; Jeong, Hyunseok
We propose a scheme of loss-resilient entanglement swapping between two distant parties via an imperfect optical channel. In this scheme, two copies of hybrid entangled states are prepared and the continuous-variable parts propagate through lossy media. In order to perform successful entanglement swapping, several different measurement schemes are considered for the continuous-variable parts such as single-photon detection for ideal cases and a homodyne detection for practical cases. We find that the entanglement swapping using hybrid states with small amplitudes offers larger entanglement than the discrete-variable entanglement swapping in the presence of large losses. Remarkably, this hybrid scheme still offers excellent robustness of entanglement to the detection inefficiency. Thus, the proposed scheme could be used for the practical quantum key distribution in hybrid optical states under photon losses.
Hypoxic hypoxia at moderate altitudes: review of the state of the science.
Petrassi, Frank A; Hodkinson, Peter D; Walters, P Lynne; Gaydos, Steven J
Unpressurized aircraft routinely operate at altitudes where hypoxia may be of concern. A systematic literature review was conducted regarding hypoxic impairment, including mental functions, sensory deficits, and other pertinent research findings that may affect aviation-related duties at moderate altitude (8000 to 15,000 ft/2438 to 4572 m). The results of this review suggest that cognitive and psychomotor deficits may include learning, reaction time, decision-making, and certain types of memory. However, results are difficult to quantify and reliably reproduce. Inconsistency of results may be related to the subtlety of deficits compared to high altitude, differences among individual compensatory mechanisms, variation in methodology or sensitivity of metrics, presence or absence of exercise, heterogeneous neuronal central nervous system (CNS) response, and interindividual variation. Literature regarding hypoxic visual decrements is more consistent. Rod photoreceptors are more susceptible to hypoxia; visual degradation has been demonstrated at 4000 to 5000 ft (1219 to 1524 m) under scotopic and 10,000 ft (3048 m) under photopic conditions. Augmented night vision goggle resolution demonstrates more resilience to mild hypoxic effects than the unaided eye under starlight conditions. Hypocapnia enhances visual sensitivity and contrast discrimination. Hyperventilation with resulting respiratory alkalosis and cerebral vasoconstriction may confound both cognitive/ psychomotor and visual experimental results. Future research should include augmentation of validated neuropsychological metrics (surrogate investigational end points) with actual flight metrics, investigation of mixed gas formulations, contribution of hypocapnic vasoconstrictive effects on hypoxic performance, and further investigation into cellular- and systems-level approaches for heterogeneous CNS response. Research is also required into the contribution of mild-moderate hypoxia in human factors- and spatial
Solid-state optical refrigeration to sub-100 Kelvin regime
Melgaard, Seth D.; Albrecht, Alexander R.; Hehlen, Markus P.; ...
We report that since the first demonstration of net cooling twenty years ago, optical refrigeration of solids has progressed to outperform all other solid-state cooling processes. It has become the first and only solid-state refrigerator capable of reaching cryogenic temperatures, and now the first solid-state cooling below 100 K. Such substantial progress required a multi-disciplinary approach of pump laser absorption enhancement, material characterization and purification, and thermal management. Here we present the culmination of two decades of progress, the record cooling to ≈91K from room temperature.
Purely optical navigation with model-based state prediction
NASA Astrophysics Data System (ADS)
Sendobry, Alexander; Graber, Thorsten; Klingauf, Uwe
State-of-the-art Inertial Navigation Systems (INS) based on Micro-Electro-Mechanical Systems (MEMS) have a lack of precision especially in GPS denied environments like urban canyons or in pure indoor missions. The proposed Optical Navigation System (ONS) provides bias free ego-motion estimates using triple redundant sensor information. In combination with a model based state prediction our system is able to estimate velocity, position and attitude of an arbitrary aircraft. Simulating a high performance flow-field estimator the algorithm can compete with conventional low-cost INS. By using measured velocities instead of accelerations the system states drift behavior is not as distinctive as for an INS.
Solid-state optical refrigeration to sub-100 Kelvin regime
Melgaard, Seth D.; Albrecht, Alexander R.; Hehlen, Markus P.; Sheik-Bahae, Mansoor
Since the first demonstration of net cooling twenty years ago, optical refrigeration of solids has progressed to outperform all other solid-state cooling processes. It has become the first and only solid-state refrigerator capable of reaching cryogenic temperatures, and now the first solid-state cooling below 100 K. Such substantial progress required a multi-disciplinary approach of pump laser absorption enhancement, material characterization and purification, and thermal management. Here we present the culmination of two decades of progress, the record cooling to ≈ 91 K from room temperature. PMID:26847703
Optical isolation in topological-edge-state photonic arrays.
El-Ganainy, Ramy; Levy, Miguel
We introduce a new type of optical isolator based on breaking time reversal symmetry in dissipative finite Su-Schrieffer-Heeger (SSH) waveguide arrays that support topological edge states at one end of the structure. In the forward propagation direction, light is launched into the edge waveguide to excite the localized topological midgap state. As a result, most of the input optical power is transmitted to the output port. On the other hand, backward reflected light encounters a propagation constant mismatch in that same channel which shifts the otherwise midgap state into one of the bands and hence becomes delocalized over the whole array. We show that under these conditions, a judicious spatial distribution of the optical dissipation across the structure can produce an isolation ratio of -50 dB. The required nonreciprocal phase shift is introduced by depositing a magnetic garnet film only on the edge waveguide and, thus, the required magnetic field can be generated by an integrated micromagnet. Similar concepts can also be applied to SSH arrays made from optical resonators.
Simulation of Five-Frequency Quasiperiodic and Related States For Convecting Flows In Moderate-Aspect-Ratio Box Geometries
NASA Astrophysics Data System (ADS)
Chiam, Keng-Hwee; Lai, Ming-Chih; Cross, M. C.; Greenside, Henry
We have developed a finite-difference code to integrate the three-dimensional Boussinesq equations for Rayleigh-Bénard convection in a box geometry with insulating or conducting side walls and no-slip boundary conditions. Motivated by the experimental observations of Walden et al [Phys. Rev. Lett., 53, 242 (1984)], we used this code to study the dynamics of moderate-aspect-ratio convecting flows as a function of Rayleigh number, Prandtl number, and aspect ratio. Our simulations were able to reproduce the occurrence of quasiperiodic states with up to five incommensurate frequencies, although the values of the frequencies differ quantitatively. We find that the five-frequency state is sensitive to small perturbations to the system, breaking down to mode-locking, intermittent, and chaotic states on small changes in the Rayleigh and Prandtl numbers and aspect ratio. In particular, small changes in the aspect ratio lead to a surprisingly large multiplicity of distinct planforms yielding vastly different dynamics.
Hall Crystal States at ν = 2 and Moderate Landau Level Mixing
NASA Astrophysics Data System (ADS)
Murthy, Ganpathy
The ν = 2 quantum Hall state at low Zeeman coupling is well known to be a translationally invariant singlet if Landau level mixing is small. At zero Zeeman interaction, as Landau level mixing increases, the translationally invariant state becomes unstable to an inhomogeneous state. This is the first realistic example of a full Hall crystal, which shows the coexistence of quantum Hall order and density wave order. The full Hall crystal differs from the more familiar Wigner crystal by a topological property, which results in it having only linearly dispersing collective modes at small q, and no q3/2 magnetophonon. I present calculations of the topological number and the collective modes.
Spatial distribution of dust's optical properties over the Sahara and Asia inferred from Moderate Resolution Imaging Spectroradiometer
NASA Astrophysics Data System (ADS)
Yoshida, M.; Haywood, J. M.; Yokohata, T.; Murakami, H.; Nakajimae, T.
There is great uncertainty regarding the role of mineral dust aerosols in Earth's climate system. One reason for this uncertainty is that the optical properties of mineral dust, such as its single scattering albedo (the ratio of scattering to total extinction), are poorly constrained because ground observations are limited to a few locations and satellite standard products are not available due to the excessively bright surface of the desert in the visible wavelength, which makes robust retrievals difficult. Here, we develop a method to estimate the spatial distributions of the aerosol single scattering albedo (ω0) and optical depth (τa), with daily 1°×1° spatial resolution using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) as well as model simulations of radiative transfer. This approach is based on the "critical surface reflectance" method developed in the literature, which estimates ω0 from the top of the atmospheric radiance. We estimate the uncertainties in ω0 over the Sahara (Asia) to be approximately 0.020 and 0.010 (0.023 and 0.017) for bands 9 and 1, respectively, while the uncertainty in τa is approximately 0.235 and 0.228 (0.464 and 0.370) for bands 9 and 1, respectively. The 5-95% range of the spatial distribution of ω0 over the Sahara (Asia) is approximately 0.90-0.94 and 0.96-0.99 (0.87-0.94 and 0.89-0.97) for bands 9 and 1, respectively, and that of τa over the Sahara (Asia) is approximately 0.8-1.4 and 0.8-1.7 (0.7-2.0 and 0.7-1.9) for bands 9 and 1, respectively. The results for the Sahara indicate a good correlation between ω0 and the surface reflectance, and between ω0 and τa. However, the relationships between ω0, τa, and surface reflectance are less clear in Asia than in the Sahara, and the ω0 values are smaller than those in the Sahara. The regions with small ω0 values are consistent with the regions where coal-burning smoke and carbonaceous aerosols are reported to be transported in previous studies
Selective cloning of Gaussian states by linear optics
Olivares, Stefano
We investigate the performance of a selective cloning machine based on linear optical elements and Gaussian measurements, which allows one to clone at will one of the two incoming input states. This machine is a complete generalization of a 1{yields}2 cloning scheme demonstrated by Andersen et al. [Phys. Rev. Lett. 94, 240503 (2005)]. The input-output fidelity is studied for a generic Gaussian input state, and the effect of nonunit quantum efficiency is also taken into account. We show that, if the states to be cloned are squeezed states with known squeezing parameter, then the fidelity can be enhanced using a third suitable squeezed state during the final stage of the cloning process. A binary communication protocol based on the selective cloning machine is also discussed.
Assessment of Moderate- and High-Temperature Geothermal Resources of the United States
Williams, Colin F.; Reed, Marshall J.; Mariner, Robert H.; DeAngelo, Jacob; Galanis, S. Peter
Scientists with the U.S. Geological Survey (USGS) recently completed an assessment of our Nation's geothermal resources. Geothermal power plants are currently operating in six states: Alaska, California, Hawaii, Idaho, Nevada, and Utah. The assessment indicates that the electric power generation potential from identified geothermal systems is 9,057 Megawatts-electric (MWe), distributed over 13 states. The mean estimated power production potential from undiscovered geothermal resources is 30,033 MWe. Additionally, another estimated 517,800 MWe could be generated through implementation of technology for creating geothermal reservoirs in regions characterized by high temperature, but low permeability, rock formations.
Yeast metabolic state identification using micro-fiber optics spectroscopy
NASA Astrophysics Data System (ADS)
Silva, J. S.; Castro, C. C.; Vicente, A. A.; Tafulo, P.; Jorge, P. A. S.; Martins, R. C.
Saccharomyces cerevisiae morphology is known to be dependent on the cell physiological state and environmental conditions. On their environment, wild yeasts tend to form complex colonies architectures, such as stress response and pseudohyphal filaments morphologies, far away from the ones found inside bioreactors, where the regular cell cycle is observed under controlled conditions (e.g. budding and flocculating colonies). In this work we explore the feasibility of using micro-fiber optics spectroscopy to classify Saccharomyces cerevisiae S288C colony structures in YPD media, under different growth conditions, such as: i) no alcohol; ii) 1 % (v/v) Ethanol; iii) 1 % (v/v) 1-butanol; iv) 1 % (v/v) Isopropanol; v) 1 % (v/v) Tert-Amyl alcohol (2 Methyl-2-butanol); vi) 0,2 % (v/v) 2-Furaldehyde; vii) 5 % (w/v) 5 (Hydroxymethyl)-furfural; and viii) 1 % (w/v) (-)-Adenosine3', 5'cyclic monophosphate. The microscopy system includes a hyperspectral camera apparatus and a micro fiber (sustained by micro manipulator) optics system for spectroscopy. Results show that micro fiber optics system spectroscopy has the potential for yeasts metabolic state identification once the spectral signatures of colonies differs from each others. This technique associated with others physico-chemical information can benefit the creation of an information system capable of providing extremely detailed information about yeast metabolic state that will aid both scientists and engineers to study and develop new biotechnological products.
Effect of Magnolia officinalis and Phellodendron amurense (Relora®) on cortisol and psychological mood state in moderately stressed subjects
Background Magnolia (Magnolia officinalis) and Phellodendron (Phellodendron amurense) barks are medicinal plants commonly used as traditional remedies for reducing stress and anxiety. Modern dietary supplements are intended to induce relaxation and reduce stress as well as stress-related eating. Previous studies have shown the combination of Magnolia/Phellodendron (MP) to reduce both cortisol exposure and the perception of stress/anxiety, while improving weight loss in subjects with stress-related eating. Competitive athletes are "stressed" by their intense exercise regimens in addition to their normal activities of daily living and thus may benefit from a natural therapy intended to modulate baseline perceptions of stress and stress hormone exposure. Methods We assessed salivary cortisol exposure and psychological mood state in 56 subjects (35 men and 21 women) screened for moderate stress and supplemented with a standardized/patented MP combination (Relora®, Next Pharmaceuticals) or Placebo for 4 weeks. Results After 4 weeks of supplementation, salivary cortisol exposure was significantly (p<0.05) lower (−18%) in the Relora group compared to Placebo. Compared to Placebo, the Relora group had significantly better (p<0.05) mood state parameters, including lower indices of Overall Stress (−11%), Tension (−13%), Depression (−20%), Anger (−42%), Fatigue (−31%), and Confusion (−27%), and higher indices of Global Mood State (+11%) and Vigor (+18%). Conclusion These results indicate that daily supplementation with a combination of Magnolia bark extract and Phellodendron bark extract (Relora®) reduces cortisol exposure and perceived daily stress, while improving a variety of mood state parameters, including lower fatigue and higher vigor. These results suggest an effective natural approach to modulating the detrimental health effects of chronic stress in moderately stressed adults. Future studies should examine the possible performance and recovery
Optical bending sensor using distributed feedback solid state dye lasers on optical fiber.
Kubota, Hiroyuki; Oomi, Soichiro; Yoshioka, Hiroaki; Watanabe, Hirofumi; Oki, Yuji
Novel type of optical fiber sensor was proposed and demonstrated. The print-like fabrication technique fabricates multiple distributed feedback solid state dye lasers on a polymeric optical fiber (POF) with tapered coupling. This multi-active-sidecore structure was easily fabricated and provides multiple functions. Mounting the lasers on the same point of a multimode POF demonstrated a bending radius sensitivity of 20 m without any supports. Two axis directional sensing without cross talk was also confirmed. A more complicated mounting formation can demonstrate a twisted POF. The temperature property of the sensor was also studied, and elimination of the temperature influence was experimentally attained.
Reversible Dehydrogenation of Magnesium Borohydride to Magnesium Triborane in the Solid State Under Moderate Conditions
Chong, Marina; Karkamkar, Abhijeet J.; Autrey, Thomas; Orimo, Shin-ichi; Jalisatgi, Satish; Jensen, Craig M.
Thermal decomposition of magnesium borohydride, Mg(BH4)2, in the solid state was studied by a combination of PCT, TGA/MS and NMR spectroscopy. Dehydrogenation of Mg(BH4)2 at 200 °C, results in the highly selective formation of magnesium triborane, Mg(B3H8)2. This process is reversible at 250 °C under 120 atm H2. Dehydrogenation at higher temperature, > 300 °C, produces a complex mixture of polyborane species. Solution phase 11B NMR spectra of the hydrolyzed decomposition products reveals the formation of the B3H8 anion, boric acid from hydrolysis of the unstable polyboranes (BnHx) (n = 3-11, x >8), and the closoborane B12H12 dianion as a minor product. A BH condensation mechanism involving metal hydride formation is proposed to explain the limited reversible hydrogen storage in magnesium borohydride.
All fiber optics circular-state swept source polarization-sensitive optical coherence tomography.
Lin, Hermann; Kao, Meng-Chun; Lai, Chih-Ming; Huang, Jyun-Cin; Kuo, Wen-Chuan
A swept source (SS)-based circular-state (CS) polarization-sensitive optical coherence tomography (PS-OCT) constructed entirely with polarization-maintaining fiber optics components is proposed with the experimental verification. By means of the proposed calibration scheme, bulk quarter-wave plates can be replaced by fiber optics polarization controllers to, therefore, realize an all-fiber optics CS SSPS-OCT. We also present a numerical dispersion compensation method, which can not only enhance the axial resolution, but also improve the signal-to-noise ratio of the images. We demonstrate that this compact and portable CS SSPS-OCT system with an accuracy comparable to bulk optics systems requires less stringent lens alignment and can possibly serve as a technology to realize PS-OCT instrument for clinical applications (e.g., endoscopy). The largest deviations in the phase retardation (PR) and fast-axis (FA) angle due to sample probe in the linear scanning and a rotation angle smaller than 65 deg were of the same order as those in stationary probe setups. The influence of fiber bending on the measured PR and FA is also investigated. The largest deviations of the PR were 3.5 deg and the measured FA change by ~12 to 21 deg. Finally, in vivo imaging of the human fingertip and nail was successfully demonstrated with a linear scanning probe.
Quantum amplification and quantum optical tapping with squeezed states and correlated quantum states
NASA Technical Reports Server (NTRS)
Ou, Z. Y.; Pereira, S. F.; Kimble, H. J.
Quantum fluctuations in a nondegenerate optical parametric amplifier (NOPA) are investigated experimentally with a squeezed state coupled into the internal idler mode of the NOPA. Reductions of the inherent quantum noise of the amplifier are observed with a minimum noise level 0.7 dB below the usual noise level of the amplifier with its idler mode in a vacuum state. With two correlated quantum fields as the amplifier's inputs and proper adjustment of the gain of the amplifier, it is shown that the amplifier's intrinsic quantum noise can be completely suppressed so that noise-free amplification is achieved. It is also shown that the NOPA, when coupled to either a squeezed state or a nonclassically correlated state, can realize quantum tapping of optical information.
Introducing single-crystal scattering and optical potentials into MCNPX: Predicting neutron emission from a convoluted moderator
Gallmeier, F. X.; Iverson, E. B.; Lu, W.; ...
Neutron transport simulation codes are an indispensable tool used for the design and construction of modern neutron scattering facilities and instrumentation. It has become increasingly clear that some neutron instrumentation has started to exploit physics that is not well-modelled by the existing codes. Particularly, the transport of neutrons through single crystals and across interfaces in MCNP(X), Geant4 and other codes ignores scattering from oriented crystals and refractive effects, and yet these are essential ingredients for the performance of monochromators and ultra-cold neutron transport respectively (to mention but two examples). In light of these developments, we have extended the MCNPX codemore » to include a single-crystal neutron scattering model and neutron reflection/refraction physics. Furthermore, we have also generated silicon scattering kernels for single crystals of definable orientation with respect to an incoming neutron beam. As a first test of these new tools, we have chosen to model the recently developed convoluted moderator concept, in which a moderating material is interleaved with layers of perfect crystals to provide an exit path for neutrons moderated to energies below the crystal s Bragg cut off at locations deep within the moderator. Studies of simple cylindrical convoluted moderator systems of 100 mm diameter and composed of polyethylene and single crystal silicon were performed with the upgraded MCNPX code and reproduced the magnitude of effects seen in experiments compared to homogeneous moderator systems. Applying different material properties for refraction and reflection, and by replacing the silicon in the models with voids, we show that the emission enhancements seen in recent experiments are primarily caused by the transparency of the silicon/void layers. Finally the convoluted moderator experiments described by Iverson et al. were simulated and we find satisfactory agreement between the measurement and the results of
Introducing single-crystal scattering and optical potentials into MCNPX: Predicting neutron emission from a convoluted moderator
Gallmeier, F. X.; Iverson, E. B.; Lu, W.; Baxter, D. V.; Muhrer, G.; Ansell, S.
Neutron transport simulation codes are an indispensable tool used for the design and construction of modern neutron scattering facilities and instrumentation. It has become increasingly clear that some neutron instrumentation has started to exploit physics that is not well-modelled by the existing codes. Particularly, the transport of neutrons through single crystals and across interfaces in MCNP(X), Geant4 and other codes ignores scattering from oriented crystals and refractive effects, and yet these are essential ingredients for the performance of monochromators and ultra-cold neutron transport respectively (to mention but two examples). In light of these developments, we have extended the MCNPX code to include a single-crystal neutron scattering model and neutron reflection/refraction physics. Furthermore, we have also generated silicon scattering kernels for single crystals of definable orientation with respect to an incoming neutron beam. As a first test of these new tools, we have chosen to model the recently developed convoluted moderator concept, in which a moderating material is interleaved with layers of perfect crystals to provide an exit path for neutrons moderated to energies below the crystal s Bragg cut off at locations deep within the moderator. Studies of simple cylindrical convoluted moderator systems of 100 mm diameter and composed of polyethylene and single crystal silicon were performed with the upgraded MCNPX code and reproduced the magnitude of effects seen in experiments compared to homogeneous moderator systems. Applying different material properties for refraction and reflection, and by replacing the silicon in the models with voids, we show that the emission enhancements seen in recent experiments are primarily caused by the transparency of the silicon/void layers. Finally the convoluted moderator experiments described by Iverson et al. were simulated and we find satisfactory agreement between the measurement and the results of
Introducing single-crystal scattering and optical potentials into MCNPX: Predicting neutron emission from a convoluted moderator
NASA Astrophysics Data System (ADS)
Gallmeier, F. X.; Iverson, E. B.; Lu, W.; Baxter, D. V.; Muhrer, G.; Ansell, S.
Neutron transport simulation codes are indispensable tools for the design and construction of modern neutron scattering facilities and instrumentation. Recently, it has become increasingly clear that some neutron instrumentation has started to exploit physics that is not well-modeled by the existing codes. In particular, the transport of neutrons through single crystals and across interfaces in MCNP(X), Geant4, and other codes ignores scattering from oriented crystals and refractive effects, and yet these are essential phenomena for the performance of monochromators and ultra-cold neutron transport respectively (to mention but two examples). In light of these developments, we have extended the MCNPX code to include a single-crystal neutron scattering model and neutron reflection/refraction physics. We have also generated silicon scattering kernels for single crystals of definable orientation. As a first test of these new tools, we have chosen to model the recently developed convoluted moderator concept, in which a moderating material is interleaved with layers of perfect crystals to provide an exit path for neutrons moderated to energies below the crystal's Bragg cut-off from locations deep within the moderator. Studies of simple cylindrical convoluted moderator systems of 100 mm diameter and composed of polyethylene and single crystal silicon were performed with the upgraded MCNPX code and reproduced the magnitude of effects seen in experiments compared to homogeneous moderator systems. Applying different material properties for refraction and reflection, and by replacing the silicon in the models with voids, we show that the emission enhancements seen in recent experiments are primarily caused by the transparency of the silicon and void layers. Finally we simulated the convoluted moderator experiments described by Iverson et al. and found satisfactory agreement between the measurements and the simulations performed with the tools we have developed.
Resonant-state expansion applied to planar open optical systems
NASA Astrophysics Data System (ADS)
Doost, M. B.; Langbein, W.; Muljarov, E. A.
The resonant-state expansion (RSE), a rigorous perturbation theory of the Brillouin-Wigner type recently developed in electrodynamics[E. A. Muljarov, W. Langbein, and R. Zimmermann, Europhys. Lett.EULEEJ0295-507510.1209/0295-5075/92/50010 92, 50010 (2010)], is applied to planar, effectively one-dimensional optical systems, such as layered dielectric slabs and Bragg reflector microcavities. It is demonstrated that the RSE converges with a power law in the basis size. Algorithms for error estimation and their reduction by extrapolation are presented and evaluated. Complex eigenfrequencies, electromagnetic fields, and the Green's function of a selection of optical systems are calculated, as well as the observable transmission spectra. In particular, we find that for a Bragg-mirror microcavity, which has sharp resonances in the spectrum, the transmission calculated using the RSE reproduces the result of the transfer- or scattering-matrix method.
Solid state electro-optic color filter and iris
NASA Technical Reports Server (NTRS)
A pair of solid state electro-optic filters (SSEF) in a binocular holder were designed and fabricated for evaluation of field sequential stereo TV applications. The electronic circuitry for use with the stereo goggles was designed and fabricated, requiring only an external video input. A polarizing screen suitable for attachment to various size TV monitors for use in conjunction with the stereo goggles was designed and fabricated. An improved engineering model 2 filter was fabricated using the bonded holder technique developed previously and integrated to a GCTA color TV camera. An engineering model color filter was fabricated and assembled using PLZT control elements. In addition, a ruggedized holder assembly was designed, fabricated and tested. This assembly provides electrical contacts, high voltage protection, and support for the fragile PLZT disk, and also permits mounting and optical alignment of the associated polarizers.
Noise thresholds for optical cluster-state quantum computation
Dawson, Christopher M.; Nielsen, Michael A.; Haselgrove, Henry L.
In this paper we do a detailed numerical investigation of the fault-tolerant threshold for optical cluster-state quantum computation. Our noise model allows both photon loss and depolarizing noise, as a general proxy for all types of local noise other than photon loss noise. We obtain a threshold region of allowed pairs of values for the two types of noise. Roughly speaking, our results show that scalable optical quantum computing is possible in the combined presence of both noise types, provided that the loss probability is less than 3x10{sup -3} and the depolarization probability is less than 10{sup -4}. Our fault-tolerant protocol involves a number of innovations, including a method for syndrome extraction known as telecorrection, whereby repeated syndrome measurements are guaranteed to agree. This paper is an extended version of Dawson et al. [Phys. Rev. Lett. 96, 020501 (2006)].
Recurrent state-switching of a two-state quantum dot laser by optical feedback
NASA Astrophysics Data System (ADS)
Virte, Martin; Breuer, Stefan; Sciamanna, Marc; Panajotov, Krassimir
In this contribution, we experimentally report recurrent switching between ground and excited state emission in a quantum dot laser controlled by optical feedback. We demonstrate that changing the phase of the optical feedback can efficiently induce switching between the two emission processes of the laser. Experimentally, by using an external mirror placed on a piezo-actuator, we were able to achieve incomplete switching between ground and excited state emission, i.e. without complete extinction of the modes. The switching takes place for variations of the external cavity length at the wavelength scale, i.e. around 1.2 um. Theoretically, we successfully link this switching behaviour with the evolution of the modal gain difference between the two modes induced by the variations of the optical feedback phase.
Optical Properties of a Vibrationally Modulated Solid State Mott Insulator
Kaiser, S.; Clark, S. R.; Nicoletti, D.; Cotugno, G.; Tobey, R. I.; Dean, N.; Lupi, S.; Okamoto, H.; Hasegawa, T.; Jaksch, D.; Cavalleri, A.
Optical pulses at THz and mid-infrared frequencies tuned to specific vibrational resonances modulate the lattice along chosen normal mode coordinates. In this way, solids can be switched between competing electronic phases and new states are created. Here, we use vibrational modulation to make electronic interactions (Hubbard-U) in Mott-insulator time dependent. Mid-infrared optical pulses excite localized molecular vibrations in ET-F2TCNQ, a prototypical one-dimensional Mott-insulator. A broadband ultrafast probe interrogates the resulting optical spectrum between THz and visible frequencies. A red-shifted charge-transfer resonance is observed, consistent with a time-averaged reduction of the electronic correlation strength U. Secondly, a sideband manifold inside of the Mott-gap appears, resulting from a periodically modulated U. The response is compared to computations based on a quantum-modulated dynamic Hubbard model. Heuristic fitting suggests asymmetric holon-doublon coupling to the molecules and that electron double-occupancies strongly squeeze the vibrational mode. PMID:24448171
Optical nanoscopy of transient states in condensed matter
Kuschewski, F.; Kehr, S.C.; Green, B.; Bauer, Ch.; Gensch, M.; Eng, L.M.
Recently, the fundamental and nanoscale understanding of complex phenomena in materials research and the life sciences, witnessed considerable progress. However, elucidating the underlying mechanisms, governed by entangled degrees of freedom such as lattice, spin, orbit, and charge for solids or conformation, electric potentials, and ligands for proteins, has remained challenging. Techniques that allow for distinguishing between different contributions to these processes are hence urgently required. In this paper we demonstrate the application of scattering-type scanning near-field optical microscopy (s-SNOM) as a novel type of nano-probe for tracking transient states of matter. We introduce a sideband-demodulation technique that allows for probing exclusively the stimuli-induced change of near-field optical properties. We exemplify this development by inspecting the decay of an electron-hole plasma generated in SiGe thin films through near-infrared laser pulses. Our approach can universally be applied to optically track ultrafast/-slow processes over the whole spectral range from UV to THz frequencies. PMID:26215769
State dissociation moderates response to dialectical behavior therapy for posttraumatic stress disorder in women with and without borderline personality disorder
Kleindienst, Nikolaus; Priebe, Kathlen; Görg, Nora; Dyer, Anne; Steil, Regina; Lyssenko, Lisa; Winter, Dorina; Schmahl, Christian; Bohus, Martin
dissociation during psychotherapeutic sessions moderates the success of an established treatment for PTSD. Patients were much more likely to substantially improve with respect to PTSD symptomatology if state dissociation during psychotherapeutic sessions was low. The article suggests that the relation between low dissociation and good response in highly symptomatic patients is stronger than previously thought. Future studies investigating the extent to which outcome might be improved when treating dissociation more vigorously than usually are necessary. PMID:27396380
Automated correlation dimension analysis of optically injected solid state lasers.
Toomey, J P; Kane, D M; Valling, S; Lindberg, A M
Nonlinear lasers are excellent systems from which to obtain high signal-to-noise experimental data of nonlinear dynamical variables to be used to develop and demonstrate robust nonlinear dynamics analysis techniques. Here we investigate the dynamical complexity of such a system: an optically injected Nd:YVO(4) solid state laser. We show that a map of the correlation dimension as a function of the injection strength and frequency detuning, extracted from the laser output power time-series data, is an excellent mirror of the dynamics map generated from a theoretical model of the system. An automated computational protocol has been designed and implemented to achieve this. The correlation dimension map is also contrasted with prior research that mapped the peak intensity of the output power as an experimentally accessible measurand reflecting the dynamical state of the system [Valling et al., Phys. Rev. A 72, 033810 (2005)].
The moderating role of state inhibitory control in the effect of evaluative conditioning on temptation and unhealthy snacking.
Haynes, Ashleigh; Kemps, Eva; Moffitt, Robyn
The current study sought to test the effect of a brief evaluative conditioning intervention on experienced temptation to indulge, and consumption of, unhealthy snack foods. We expected that a training task associating unhealthy food with negative affect would result in lower experienced temptation across the sample, but would lead to lower snack consumption only among individuals with low state inhibitory control. Undergraduate women (N=134) aged 17-25 years were randomised to complete an evaluative conditioning procedure pairing unhealthy food with either positive or negative affect. Snack consumption was subsequently assessed using a taste-test procedure which offered four snack foods for ad libitum consumption. Participants also reported the strength of their experienced temptation to indulge in the foods presented. Additionally, they completed a Stop Signal Task as a measure of state inhibitory control. As predicted, participants in the food negative condition ate less than those in the food positive condition, but this effect was only observed among individuals with low inhibitory control. The same moderation pattern was observed for the effect of evaluative conditioning on temptation: only participants with low inhibitory control reported feeling less tempted by the snack foods in the food negative condition compared to the food positive condition. In addition, temptation mediated the effect of evaluative conditioning on intake for individuals with low inhibitory control. Findings suggest that evaluative conditioning of unhealthy food stimuli could be especially useful for reducing temptation and consumption of unhealthy snacks in situations where individuals experience low inhibitory control capacity.
Online technique for detecting state of onboard fiber optic gyroscope.
Miao, Zhiyong; Xu, Dingjie; He, Kunpeng; Pang, Shuwan; Tian, Chunmiao
Although angle random walk (ARW) of fiber optic gyroscope (FOG) has been well modeled and identified before being integrated into the high-accuracy attitude control system of satellite, aging and unexpected failures can affect the performance of FOG after launch, resulting in the variation of ARW coefficient. Therefore, the ARW coefficient can be regarded as an indicator of "state of health" for FOG diagnosis in some sense. The Allan variance method can be used to estimate ARW coefficient of FOG, however, it requires a large amount of data to be stored. Moreover, the procedure of drawing slope lines for estimation is painful. To overcome the barriers, a weighted state-space model that directly models the ARW to obtain a nonlinear state-space model was established for FOG. Then, a neural extended-Kalman filter algorithm was implemented to estimate and track the variation of ARW in real time. The results of experiment show that the proposed approach is valid to detect the state of FOG. Moreover, the proposed technique effectively avoids the storage of data.
Online technique for detecting state of onboard fiber optic gyroscope
Miao, Zhiyong; He, Kunpeng Pang, Shuwan; Xu, Dingjie; Tian, Chunmiao
Although angle random walk (ARW) of fiber optic gyroscope (FOG) has been well modeled and identified before being integrated into the high-accuracy attitude control system of satellite, aging and unexpected failures can affect the performance of FOG after launch, resulting in the variation of ARW coefficient. Therefore, the ARW coefficient can be regarded as an indicator of "state of health" for FOG diagnosis in some sense. The Allan variance method can be used to estimate ARW coefficient of FOG, however, it requires a large amount of data to be stored. Moreover, the procedure of drawing slope lines for estimation is painful. To overcome the barriers, a weighted state-space model that directly models the ARW to obtain a nonlinear state-space model was established for FOG. Then, a neural extended-Kalman filter algorithm was implemented to estimate and track the variation of ARW in real time. The results of experiment show that the proposed approach is valid to detect the state of FOG. Moreover, the proposed technique effectively avoids the storage of data.
Magneto-optical controlled transmittance alteration of PbS quantum dots by moderately applied magnetic fields at room temperature
Singh, Akhilesh K.; Barik, Puspendu; Ullrich, Bruno E-mail: email@example.com
We observed changes of the transmitted monochromatic light passing through a colloidal PbS quantum dot film on glass owing to an applied moderate (smaller than 1 T) magnetic field under ambient conditions. The observed alterations show a square dependence on the magnetic field increase that cannot be achieved with bulk semiconductors. The findings point to so far not recognized application potentials of quantum dots.
Magneto-optical controlled transmittance alteration of PbS quantum dots by moderately applied magnetic fields at room temperature
NASA Astrophysics Data System (ADS)
Singh, Akhilesh K.; Barik, Puspendu; Ullrich, Bruno
We observed changes of the transmitted monochromatic light passing through a colloidal PbS quantum dot film on glass owing to an applied moderate (smaller than 1 T) magnetic field under ambient conditions. The observed alterations show a square dependence on the magnetic field increase that cannot be achieved with bulk semiconductors. The findings point to so far not recognized application potentials of quantum dots.
Noninvasive optical cytochrome c oxidase redox state measurements using diffuse optical spectroscopy
NASA Astrophysics Data System (ADS)
Lee, Jangwoen; Kim, Jae G.; Mahon, Sari B.; Mukai, David; Yoon, David; Boss, Gerry R.; Patterson, Steven E.; Rockwood, Gary; Isom, Gary; Brenner, Matthew
A major need exists for methods to assess organ oxidative metabolic states in vivo. By contrasting the responses to cyanide (CN) poisoning versus hemorrhage in animal models, we demonstrate that diffuse optical spectroscopy (DOS) can detect cytochrome c oxidase (CcO) redox states. Intermittent decreases in inspired O2 from 100% to 21% were applied before, during, and after CN poisoning, hemorrhage, and resuscitation in rabbits. Continuous DOS measurements of total hemoglobin, oxyhemoglobin, deoxyhemoglobin, and oxidized and reduced CcO from muscle were obtained. Rabbit hemorrhage was accomplished with stepwise removal of blood, followed by blood resuscitation. CN treated rabbits received 0.166 mg/min NaCN infusion. During hemorrhage, CcO redox state became reduced concurrently with decreases in oxyhemoglobin, resulting from reduced tissue oxygen delivery and hypoxia. In contrast, during CN infusion, CcO redox state decreased while oxyhemoglobin concentration increased due to CN binding and reduction of CcO with resultant inhibition of the electron transport chain. Spectral absorption similarities between hemoglobin and CcO make noninvasive spectroscopic distinction of CcO redox states difficult. By contrasting physiological perturbations of CN poisoning versus hemorrhage, we demonstrate that DOS measured CcO redox state changes are decoupled from hemoglobin concentration measurement changes.
Optoelectronic device simulation: Optical modeling for semiconductor optical amplifiers and solid state lighting
NASA Astrophysics Data System (ADS)
Wang, Dong-Xue (Michael)
transparency carrier densities; the differential gain is assumed constant accordingly. This assumption is only valid for wavelengths close to the gain peak wavelength. As a result, high accuracy for wideband wavelength conversion is not guaranteed. We proposed a steady state numerical model of wavelength converters based on cross-gain modulation in semiconductor optical amplifiers. In this model, a new model of the gain coefficient developed by Connelly was applied, which also includes the internal loss variation with the electron carrier density. Each physical variable, such as the carrier density, gain coefficient, differential gain, and internal loss, spatially varies across the SOA cavity and is numerically calculated throughout the device. This model can predicts wavelength-dependent characteristics of a wavelength converter of the SOA in both large and small signal regimes. Some key performance factors of SOA wavelength converters, such as selection of pump and probe wavelengths and power, length of SOA cavities, conversion efficiency and bandwidth, system performance difference between up and down conversions can be modeled and optimized using this numerical model. Most LED modeling techniques are based on optical ray tracing to predict the light extraction efficiency, and the light extraction efficiency is a critical parameter to evaluate LEDs. Here, we proposed a hybrid method to simulate the lighting efficiency of LED chips, where both guided wave theory and geometric optical ray tracing are applied. Guided wave optics is used to identify guided modes and leakage modes inside the LED active layer, and its device structure can be optimized to increase leakage modes so that the lighting extraction efficiency is improved. On the other hand, Monte Carlo optical ray tracing is used to quantitatively determine optical extraction efficiency. Moreover, this method can model the light distribution and far-field illumination pattern. Both single wavelength LEDs and dual
Quantum state control and characterization in an optical lattice
NASA Astrophysics Data System (ADS)
Myrskog, Stefan Henrik
In this dissertation I present experimental work on the measurement and manipulation of the center-of-mass motion of laser-cooled atoms. The first experiment described demonstrates cooling of an atom cloud by 'delta-kick cooling'. A thermal cloud of atoms in a vacuum expands ballistically, generating correlations between position and momentum. An appropriate momentum kick, proportional to position, results in slowing down all the atoms in the cloud. Through this technique a cloud of atoms can be cooled by greater than a factor of 10, preserving phase-space density, but decreasing the number density of atoms. By using laser-cooled atoms, it is also possible to confine atoms in potentials created by the AC-Stark shift of the atomic energy levels. Using interfering lasers to create the Stark shift, atoms are confined in a sinusoidal potential called an optical lattice. After preparing atoms in the lowest-energy band of the lattice, a spatial displacement can create coherent superpositions of many states of the potential. A combination of time delays and secondary displacements allows the measurement of the Q (Husimi) and W (Wigner) quasi-probability distributions, each of which completely characterizes the motional state of the atoms. Alternatively, a shallow lattice that only support two long-lived states can be used. The two-state system may be characterized with far fewer measurements, and furthermore, can be used as a model system for a qubit, a quantum representation of a single bit of information, useful for quantum computation. We demonstrate reconstruction of the density matrix in the 2-state system. The two-state system has be further used to characterize the physical action of an operation. By preparing a complete set of input density matrices we perform quantum process tomography for the intrinsic decoherence of the lattice, and two operations that correspond to single qubit rotations.
State diagrams for harmonically trapped bosons in optical lattices
Rigol, Marcos; Batrouni, George G.; Rousseau, Valery G.; Scalettar, Richard T.
We use quantum Monte Carlo simulations to obtain zero-temperature state diagrams for strongly correlated lattice bosons in one and two dimensions under the influence of a harmonic confining potential. Since harmonic traps generate a coexistence of superfluid and Mott insulating domains, we use local quantities such as the quantum fluctuations of the density and a local compressibility to identify the phases present in the inhomogeneous density profiles. We emphasize the use of the 'characteristic density' to produce a state diagram that is relevant to experimental optical lattice systems, regardless of the number of bosons or trap curvature and of the validity of the local-density approximation. We show that the critical value of U/t at which Mott insulating domains appear in the trap depends on the filling in the system, and it is in general greater than the value in the homogeneous system. Recent experimental results by Spielman et al. [Phys. Rev. Lett. 100, 120402 (2008)] are analyzed in the context of our two-dimensional state diagram, and shown to exhibit a value for the critical point in good agreement with simulations. We also study the effects of finite, but low (T{<=}t/2), temperatures. We find that in two dimensions they have little influence on our zero-temperature results, while their effect is more pronounced in one dimension.
Wavelets and the squeezed states of quantum optics
NASA Technical Reports Server (NTRS)
Defacio, B.
Wavelets are new mathematical objects which act as 'designer trigonometric functions.' To obtain a wavelet, the original function space of finite energy signals is generalized to a phase-space, and the translation operator in the original space has a scale change in the new variable adjoined to the translation. Localization properties in the phase-space can be improved and unconditional bases are obtained for a broad class of function and distribution spaces. Operators in phase space are 'almost diagonal' instead of the traditional condition of being diagonal in the original function space. These wavelets are applied to the squeezed states of quantum optics. The scale change required for a quantum wavelet is shown to be a Yuen squeeze operator acting on an arbitrary density operator.
Pre-seizure state identified by diffuse optical tomography
Zhang, Tao; Zhou, Junli; Jiang, Ruixin; Yang, Hao; Carney, Paul R.; Jiang, Huabei
In epilepsy it has been challenging to detect early changes in brain activity that occurs prior to seizure onset and to map their origin and evolution for possible intervention. Here we demonstrate using a rat model of generalized epilepsy that diffuse optical tomography (DOT) provides a unique functional neuroimaging modality for noninvasively and continuously tracking such brain activities with high spatiotemporal resolution. We detected early hemodynamic responses with heterogeneous patterns, along with intracranial electroencephalogram gamma power changes, several minutes preceding the electroencephalographic seizure onset, supporting the presence of a "pre-seizure" state. We also observed the decoupling between local hemodynamic and neural activities. We found widespread hemodynamic changes evolving from local regions of the bilateral cortex and thalamus to the entire brain, indicating that the onset of generalized seizures may originate locally rather than diffusely. Together, these findings suggest DOT represents a powerful tool for mapping early seizure onset and propagation pathways. PMID:24445927
Solid-state detector and optical system for microchip analyzers
Mathies, Richard A.; Kamei, Toshihiro; Scherer, James R.; Street, Robert A.
A miniaturized optical excitation and detector system is described for detecting fluorescently labeled analytes in electrophoretic microchips and microarrays. The system uses miniature integrated components, light collection, optical fluorescence filtering, and an amorphous a-Si:H detector for detection. The collection of light is accomplished with proximity gathering and/or a micro-lens system. Optical filtering is accomplished by integrated optical filters. Detection is accomplished utilizing a-Si:H detectors.
Optical pumping of metastable NH radicals into the paramagnetic ground state
Meerakker, Sebastiaan Y.T. van de; Mosk, Allard P.; Jongma, Rienk T.; Sartakov, Boris G.; Meijer, Gerard
We here report on the optical pumping of both {sup 14}NH and {sup 15}NH radicals from the metastable a {sup 1}{delta} state into the X {sup 3}{sigma}{sup -} ground state in a molecular beam experiment. By inducing the hitherto unobserved spin-forbidden A {sup 3}{pi} <- a {sup 1}{delta} transition, followed by spontaneous emission to the X {sup 3}{sigma}{sup -} state, a unidirectional pathway for population transfer from the metastable state into the electronic ground state is obtained. The optical pumping scheme demonstrated here opens up the possibility to accumulate NH radicals in a magnetic or optical trap.
Long-term monitoring of PKS 2155-304 with ATOM and H.E.S.S.: investigation of optical/γ-ray correlations in different spectral states
NASA Astrophysics Data System (ADS)
H.E.S.S. Collaboration; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Angüner, E. O.; Backes, M.; Balenderan, S.; Balzer, A.; Barnacka, A.; Becherini, Y.; Becker Tjus, J.; Berge, D.; Bernhard, S.; Bernlöhr, K.; Birsin, E.; Biteau, J.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Bulik, T.; Carrigan, S.; Casanova, S.; Chadwick, P. M.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Conrad, J.; Couturier, C.; Cui, Y.; Dalton, M.; Davids, I. D.; Degrange, B.; Deil, C.; deWilt, P.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; O'C. Drury, L.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Edwards, T.; Egberts, K.; Eger, P.; Espigat, P.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fernandez, D.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Grondin, M.-H.; Grudzińska, M.; Hadsch, D.; Häffner, S.; Hahn, J.; Harris, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Ivascenko, A.; Jacholkowska, A.; Jahn, C.; Jamrozy, M.; Janiak, M.; Jankowsky, F.; Jung, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Khélifi, B.; Kieffer, M.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lefaucheur, J.; Lefranc, V.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Méhault, J.; Meintjes, P. J.; Menzler, U.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Morå, K.; Moulin, E.; Murach, T.; de Naurois, M.; Niemiec, J.; Nolan, S. J.; Oakes, L.; Odaka, H.; Ohm, S.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Parsons, R. D.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perez, J.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Poon, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reichardt, I.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Rob, L.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tluczykont, M.; Trichard, C.; Valerius, K.; van Eldik, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Völk, H. J.; Volpe, F.; Vorster, M.; Vuillaume, T.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; Ward, M.; Weidinger, M.; Weitzel, Q.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.
In this paper we report on the analysis of all the available optical and very high-energy γ-ray (>200 GeV) data for the BL Lac object PKS 2155-304, collected simultaneously with the ATOM and H.E.S.S. telescopes from 2007 until 2009. This study also includes X-ray (RXTE, Swift) and high-energy γ-ray (Fermi-LAT) data. During the period analysed, the source was transitioning from its flaring to quiescent optical states, and was characterized by only moderate flux changes at different wavelengths on the timescales of days and months. A flattening of the optical continuum with an increasing optical flux can be noted in the collected dataset, but only occasionally and only at higher flux levels. We did not find any universal relation between the very high-energy γ-ray and optical flux changes on the timescales from days and weeks up to several years. On the other hand, we noted that at higher flux levels the source can follow two distinct tracks in the optical flux-colour diagrams, which seem to be related to distinct γ-ray states of the blazar. The obtained results therefore indicate a complex scaling between the optical and γ-ray emission of PKS 2155-304, with different correlation patterns holding at different epochs, and a γ-ray flux depending on the combination of an optical flux and colour rather than a flux alone.
Vibrational states and optical transitions in hydrogen bonds
NASA Astrophysics Data System (ADS)
Johannsen, P. G.
Proton energies in hydrogen bonds are mostly calculated using a double Morse potential (the DMP model). This form, however, does not reproduce the experimentally observed correlation between the proton stretching frequency and the bond length in an extended bond-length region sufficiently well. An alternative potential is proposed in the present paper. The quantum states of this non-symmetric double-well potential are calculated numerically using the Numerov (Fox-Goodwin) algorithm. It is shown that the optical spectra of hydrogen bonds in various substances can be well approximated on the basis of the transition frequencies and intensities predicted by the present model. For weakly interacting OH impurities in 0953-8984/10/10/008/img1, the overtone spectrum and line intensities are well reproduced, whereas the line broadenings and the decrease of the fundamental stretching frequencies in intermediate and strong hydrogen bonds are traced back to the influence of the reduced height of the central barrier. The model is also extrapolated to the range of symmetric hydrogen bonds, and the calculated transition frequencies are discussed with respect to most recent infra-red experiments on ice under strong compression. A possible artificial infra-red signal from strained diamond anvils is thereby noted.
Optically triggered solid state driver for shock wave therapy
NASA Astrophysics Data System (ADS)
Duryea, Alexander P.; Roberts, William W.; Cain, Charles A.; Hall, Timothy L.
Shock wave lithotripsy (SWL) represents one of several first-line therapies for the treatment of stones located in the kidneys and ureters. Additional applications for shock wave therapy are also under exploration, including non-urinary calculi, orthopedics, and neovascularization. Except for the elimination of a large water bath in which the treatment is performed, current procedures remain largely unchanged, with one of the original commercial devices (the Dornier HM3) still considered a gold standard for comparison. To accelerate research in this area, Coleman, et al. published an experimental electrohydraulic shock wave generator capable of simulating the acoustic field generated by the HM3. We propose a further update of this system, replacing the triggered spark gap with an optically triggered solid state switch. The new system has better reliability, a wider operating range, and reduced timing jitter allowing synchronization with additional acoustic sources under exploration for improving efficacy and reducing injury. Originally designed for exciting electrohydraulic spark electrodes, the system can also be adapted for driving piezoelectric and electromagnetic sources.
The rich get richer and the poor get poorer: Country- and state-level income inequality moderates the job insecurity-burnout relationship.
Jiang, Lixin; Probst, Tahira M
Despite the prevalence of income inequality in today's society, research on the implications of income inequality for organizational research is scant. This study takes the first step to explore the contextual role of national- and state- level income inequality as a moderator in the relationship between individual-level job insecurity (JI) and burnout. Drawing from conservation of resource (COR) theory, we argue that income inequality at the country-level and state-level threatens one's obtainment of object (i.e., material coping) and condition (i.e., nonmaterial coping) resources, thus serving as an environmental stressor exacerbating one's burnout reactions to JI. The predicted cross-level interaction effect of income inequality was tested in 2 studies. Study 1 consisting of 23,778 individuals nested in 30 countries explored the moderating effect of country-level income inequality on the relationship between individual JI and exhaustion. Study 2 collected data from 402 employees residing in 48 states in the United States, and tested the moderating effect of state-level income inequality on the relationship between JI and burnout (i.e., emotional exhaustion and cynicism). Results of both studies converge to support the exacerbating role of higher-level income inequality on the JI -burnout relationship. Our findings contribute to the literature on psychological health disparities by exploring the contextual role of income inequality as a predictor of differential reactions to JI. (PsycINFO Database Record
Vision science and adaptive optics, the state of the field.
Marcos, Susana; Werner, John S; Burns, Stephen A; Merigan, William H; Artal, Pablo; Atchison, David A; Hampson, Karen M; Legras, Richard; Lundstrom, Linda; Yoon, Geungyoung; Carroll, Joseph; Choi, Stacey S; Doble, Nathan; Dubis, Adam M; Dubra, Alfredo; Elsner, Ann; Jonnal, Ravi; Miller, Donald T; Paques, Michel; Smithson, Hannah E; Young, Laura K; Zhang, Yuhua; Campbell, Melanie; Hunter, Jennifer; Metha, Andrew; Palczewska, Grazyna; Schallek, Jesse; Sincich, Lawrence C
Adaptive optics is a relatively new field, yet it is spreading rapidly and allows new questions to be asked about how the visual system is organized. The editors of this feature issue have posed a series of question to scientists involved in using adaptive optics in vision science. The questions are focused on three main areas. In the first we investigate the use of adaptive optics for psychophysical measurements of visual system function and for improving the optics of the eye. In the second, we look at the applications and impact of adaptive optics on retinal imaging and its promise for basic and applied research. In the third, we explore how adaptive optics is being used to improve our understanding of the neurophysiology of the visual system.
Optically Excited Entangled States in Organic Molecules Illuminate the Dark.
Upton, L; Harpham, M; Suzer, O; Richter, M; Mukamel, S; Goodson, T
We utilize quantum entangled photons to carry out nonlinear optical spectroscopy in organic molecules with an extremely small number of photons. For the first time, fluorescence is reported as a result of entangled photon absorption in organic nonlinear optical molecules. Selectivity of the entangled photon absorption process is also observed and a theoretical model of this process is provided. Through these experiments and theoretical modeling it is found that while some molecules may not have strong classical nonlinear optical properties due to their excitation pathways; these same excitation pathways may enhance the entangled photon processes. It is found that the opposite is also true. Some materials with weak classical nonlinear optical effects may exhibit strong non-classical nonlinear optical effects. Our entangled photon fluorescence results provide the first steps in realizing and demonstrating the viability of entangled two-photon microscopy, remote sensing, and optical communications.
Optical Properties of Moderately-Absorbing Organic and Mixed Organic/Inorganic Particles at Very High Humidities
Bond, Tami C; Rood, Mark J; Brem, Benjamin T; Mena-Gonzalez, Francisco C; Chen, Yanju
Relative humidity (RH) affects the water content of an aerosol, altering its ability to scatter and absorb light, which is important for aerosol effects on climate and visibility. This project involves in situ measurement and modeling of aerosol optical properties including absorption, scattering and extinction at three visible wavelengths (467, 530, 660 nm), for organic carbon (OC) generated by pyrolysis of biomass, ammonium sulfate and sodium chloride, and their mixtures at controlled RH conditions. Novel components of this project include investigation of: (1) Changes in all three of these optical properties at scanned RH conditions; (2) Optical properties at RH values up to 95%, which are usually extrapolated instead of measured; and (3) Examination of aerosols generated by the pyrolysis of wood, which is representative of primary atmospheric organic carbon, and its mixture with inorganic aerosol. Scattering and extinction values were used to determine light absorption by difference and single scattering albedo values. Extensive instrumentation development and benchmarking with independently measured and modeled values were used to obtain and evaluate these new results. The single scattering albedo value for a dry absorbing polystyrene microsphere benchmark agreed within 0.02 (absolute value) with independently published results at 530 nm. Light absorption by a nigrosin (sample light-absorbing) benchmark increased by a factor of 1.24 +/-0.06 at all wavelengths as RH increased from 38 to 95%. Closure modeling with Mie theory was able to reproduce this increase with the linear volume average (LVA) refractive index mixing rule for this water soluble compound. Absorption by biomass OC aerosol increased by a factor of 2.1 +/- 0.7 and 2.3 +/- 1.2 between 32 and 95% RH at 467 nm and 530 nm, but there was no detectable absorption at 660 nm. Additionally, the spectral dependence of absorption by OC that was observed with filter measurements was confirmed qualitatively
Remote sensing-based Information for crop monitoring: contribution of SAR and Moderate resolution optical data on Asian rice production
NASA Astrophysics Data System (ADS)
Boschetti, Mirco; Holectz, Francesco; Manfron, Giacinto; Collivignarelli, Francesco; Nelson, Andrew
Updated information on crop typology and status are strongly required to support suitable action to better manage agriculture production and reduce food insecurity. In this field, remote sensing has been demonstrated to be a suitable tool to monitor crop condition however rarely the tested system became really operative. The ones today available, such as the European Commission MARS, are mainly based on the analysis of NDVI time series and required ancillary external information like crop mask to interpret the seasonal signal. This condition is not always guarantied worldwide reducing the potentiality of the remote sensing monitoring. Moreover in tropical countries cloud contamination strongly reduce the possibility of using optical remote sensing data for crop monitoring. In this framework we focused our analysis on the rice production monitoring in Asian tropical area. Rice is in fact the staple food for half of the world population (FAO 2004), in Asia almost 90% of the world's rice is produced and consumed and Rice and poverty often coincide. In this contest the production of reliable rice production information is of extreme interest. We tried to address two important issue in terms of required geospatial information for crop monitoring: rice crop detection (rice map) and seasonal dynamics analysis (phenology). We use both SAR and Optical data in order to exploit the potential complementarity of this system. Multi-temporal ASAR Wide Swath data are in fact the best option to deal with cloud contamination. SAR can easily penetrate the clouds providing information on the surface target. Temporal analysis of archive ASAR data allowed to derived accurate map, at 100m spatial resolution, of permanent rice cultivated areas. On the other and high frequency revisiting optical data, in this case MODIS, have been used to extract seasonal information for the year under analysis. MOD09A1 Surface Reflectance 8-Day L3 Global 500m have been exploited to derive time series of
Effect of hybrid state of surface plasmon-polaritons, magnetic defect mode and optical Tamm state on nonreciprocal propagation
NASA Astrophysics Data System (ADS)
Fang, Yun-tuan; Ni, Yue-xin; He, Hang-qing; Hu, Jian-xia
A coupled system of semi-infinite one-dimensional photonic crystal coated with metal and magnetic films is proposed. The properties of hybrid states of surface plasmon-polaritons, magnetic defect mode and optical Tamm state from the system have been studied through the Bloch theorem of periodic structure and the transfer matrix method. In the hybrid states the magneto-optical effect is amplified due to the field resonance amplification at the interface between the metal and magneto-optical material. Tunable nonreciprocal propagation can be achieved from the hybrid states through changing the thickness of magneto-optical material layer. The nonreciprocity is found to be robust to the change of metal thickness.
Spontaneous Facial Mimicry Is Enhanced by the Goal of Inferring Emotional States: Evidence for Moderation of "Automatic" Mimicry by Higher Cognitive Processes
Murata, Aiko; Saito, Hisamichi; Schug, Joanna; Ogawa, Kenji; Kameda, Tatsuya
A number of studies have shown that individuals often spontaneously mimic the facial expressions of others, a tendency known as facial mimicry. This tendency has generally been considered a reflex-like "automatic" response, but several recent studies have shown that the degree of mimicry may be moderated by contextual information. However, the cognitive and motivational factors underlying the contextual moderation of facial mimicry require further empirical investigation. In this study, we present evidence that the degree to which participants spontaneously mimic a target's facial expressions depends on whether participants are motivated to infer the target's emotional state. In the first study we show that facial mimicry, assessed by facial electromyography, occurs more frequently when participants are specifically instructed to infer a target's emotional state than when given no instruction. In the second study, we replicate this effect using the Facial Action Coding System to show that participants are more likely to mimic facial expressions of emotion when they are asked to infer the target's emotional state, rather than make inferences about a physical trait unrelated to emotion. These results provide convergent evidence that the explicit goal of understanding a target's emotional state affects the degree of facial mimicry shown by the perceiver, suggesting moderation of reflex-like motor activities by higher cognitive processes. PMID:27055206
Spontaneous Facial Mimicry Is Enhanced by the Goal of Inferring Emotional States: Evidence for Moderation of "Automatic" Mimicry by Higher Cognitive Processes.
Murata, Aiko; Saito, Hisamichi; Schug, Joanna; Ogawa, Kenji; Kameda, Tatsuya
A number of studies have shown that individuals often spontaneously mimic the facial expressions of others, a tendency known as facial mimicry. This tendency has generally been considered a reflex-like "automatic" response, but several recent studies have shown that the degree of mimicry may be moderated by contextual information. However, the cognitive and motivational factors underlying the contextual moderation of facial mimicry require further empirical investigation. In this study, we present evidence that the degree to which participants spontaneously mimic a target's facial expressions depends on whether participants are motivated to infer the target's emotional state. In the first study we show that facial mimicry, assessed by facial electromyography, occurs more frequently when participants are specifically instructed to infer a target's emotional state than when given no instruction. In the second study, we replicate this effect using the Facial Action Coding System to show that participants are more likely to mimic facial expressions of emotion when they are asked to infer the target's emotional state, rather than make inferences about a physical trait unrelated to emotion. These results provide convergent evidence that the explicit goal of understanding a target's emotional state affects the degree of facial mimicry shown by the perceiver, suggesting moderation of reflex-like motor activities by higher cognitive processes.
Generation of two types of nonclassical optical states using an optical parametric oscillator with a PPKTP crystal
NASA Astrophysics Data System (ADS)
Huo, Meiru; Qin, Jiliang; Yan, Zhihui; Jia, Xiaojun; Peng, Kunchi
As important members of nonclassical states of light, squeezed states and entangled states are basic resources for realizing quantum measurements and constructing quantum information networks. We experimentally demonstrate that the two types of nonclassical optical states can be generated from an optical parametric oscillator (OPO) involving a periodically poled KTiOPO4 crystal with a domain-inversion period of 51.7 μm, by changing the polarization of the pump laser. When a vertically polarized 671 nm laser is used to pump the OPO, the intra-cavity frequency-down-conversion with type-0 quasi-phase matching is realized and the output optical beam is a quadrature amplitude squeezed state of light at the wavelength of 1342 nm with the fluctuation of quadrature component of 3.17 dB below the quantum noise limit (QNL). If the pump laser is horizontally polarized, the condition of the type-II quasi-phase matching is satisfied and the output optical beam becomes Einstein-Podolsky-Rosen entangled state of light with correlation variances of both quadrature amplitude-sum and quadrature phase-difference of 2.2 dB below the corresponding QNL.
Experimental generation of tripartite polarization entangled states of bright optical beams
NASA Astrophysics Data System (ADS)
Wu, Liang; Yan, Zhihui; Liu, Yanhong; Deng, Ruijie; Jia, Xiaojun; Xie, Changde; Peng, Kunchi
The multipartite polarization entangled states of bright optical beams directly associating with the spin states of atomic ensembles are one of the essential resources in the future quantum information networks, which can be conveniently utilized to transfer and convert quantum states across a network composed of many atomic nodes. In this letter, we present the experimental demonstration of tripartite polarization entanglement described by Stokes operators of optical field. The tripartite entangled states of light at the frequency resonant with D1 line of Rubidium atoms are transformed into the continuous variable polarization entanglement among three bright optical beams via an optical beam splitter network. The obtained entanglement is confirmed by the extended criterion for polarization entanglement of multipartite quantized optical modes.
Switching between ground and excited states by optical feedback in a quantum dot laser diode
Virte, Martin; Breuer, Stefan; Sciamanna, Marc; Panajotov, Krassimir
We demonstrate switching between ground state and excited state emission in a quantum-dot laser subject to optical feedback. Even though the solitary laser emits only from the excited state, we can trigger the emission of the ground state by optical feedback. We observe recurrent but incomplete switching between the two emission states by variation of the external cavity length in the sub-micrometer scale. We obtain a good qualitative agreement of experimental results with simulation results obtained by a rate equation that accounts for the variations of the feedback phase.
Single-photon-state generation from a continuous-wave nondegenerate optical parametric oscillator
Nielsen, Anne E. B.; Moelmer, Klaus
We present a theoretical treatment of conditional preparation of one-photon states from a continuous-wave nondegenerate optical parametric oscillator. We obtain an analytical expression for the output state Wigner function, and we maximize the one-photon state fidelity by varying the temporal mode function of the output state. We show that a higher production rate of high fidelity Fock states is obtained if we condition the outcome on dark intervals around trigger photo detection events.
The effects of advertisements that sexually objectify women on state body dissatisfaction and judgments of women: The moderating roles of gender and internalization.
Krawczyk, Ross; Thompson, J Kevin
Experimental studies have demonstrated that exposure to idealized images of women increases state body image disturbance. However, little work has experimentally examined the effects of exposure to images that sexually objectify women, especially as it relates to women and men's state body dissatisfaction and judgments of women. In the current study, 437 women and men were randomly assigned to view advertisements that sexually objectify women and portray appearance ideals, or to view non-appearance-related advertisements. Results indicated that state body dissatisfaction increased for women and men exposed to advertisements that sexually objectified women, although this effect was larger for women. Trait internalization of appearance ideals moderated this effect, indicating that women and men with higher internalization exhibited greater state body dissatisfaction after viewing women sexually objectified in advertisements. Exposure to women sexually objectified in advertisements did not affect women's or men's attractiveness or competence ratings of women in university advertisements.
Optical Field-Strength Polarization of Two-Mode Single-Photon States
ERIC Educational Resources Information Center
Linares, J.; Nistal, M. C.; Barral, D.; Moreno, V.
We present a quantum analysis of two-mode single-photon states based on the probability distributions of the optical field strength (or position quadrature) in order to describe their quantum polarization characteristics, where polarization is understood as a significative confinement of the optical field-strength values on determined regions of…
Radical ions and excited states in radiolysis. Optically detected time resolved EPR
Trifunac, A.D.; Smith, J.P.
Excited-state production and radical-ion recombination kinetics in pulse-irradiated solutions of aromatic solutes in cyclohexane are studied by a new method of optical detection of time-resolved electron paramagnetic resonance (EPR) spectra. 7 figures.
Block-free optical quantum Banyan network based on quantum state fusion and fission
NASA Astrophysics Data System (ADS)
Zhu, Chang-Hua; Meng, Yan-Hong; Quan, Dong-Xiao; Zhao, Nan; Pei, Chang-Xing
Optical switch fabric plays an important role in building multiple-user optical quantum communication networks. Owing to its self-routing property and low complexity, a banyan network is widely used for building switch fabric. While, there is no efficient way to remove internal blocking in a banyan network in a classical way, quantum state fusion, by which the two-dimensional internal quantum states of two photons could be combined into a four-dimensional internal state of a single photon, makes it possible to solve this problem. In this paper, we convert the output mode of quantum state fusion from spatial-polarization mode into time-polarization mode. By combining modified quantum state fusion and quantum state fission with quantum Fredkin gate, we propose a practical scheme to build an optical quantum switch unit which is block free. The scheme can be extended to building more complex units, four of which are shown in this paper.
Energy shift and state mixing of Rydberg atoms in ponderomotive optical traps
NASA Astrophysics Data System (ADS)
Wang, Xiao; Robicheaux, F.
We present a degenerate perturbation analysis in the spin-orbit coupled basis for Rydberg atoms in an optical trap. The perturbation matrix is found to be nearly the same for two states with the same total angular momentum j, and orbital angular momentum number l differing by 1, The same perturbation matrices result in the same state-mixing and energy shift. We also study the dependence of state mixing and energy shift on the periodicity and symmetry of the ponderomotive potentials induced by different optical traps. State mixing in a one-dimensional lattice formed with two counterpropagating Gaussian beams is studied and yields a state-dependent trap depth. We also calculate the state-mixing in an optical trap formed by four parallel, separated and highly focused Gaussian beams.
Optical Limiting: An Overview State of the Art Report
optical limiting response of phthalocyanine and porphyrin complexes23.24.25. Explored structural variations include insertion of metal ions , extension...electromagnetic field, damage threshold, reverse saturable absorption (RSA), Porphyrin, 14. SUBJECT TERMS 49 Tetrabenzoporphyrin, Metal Bis( phthalocyanine ...Structure of Tetrabenzoporphyrin (A) and Tetraphenylporphyrin (B) 20 Chemical Structure of Phthalocyanine 21 Chemical Structure of Metal
Spectral structure and decompositions of optical states, and their applications
NASA Astrophysics Data System (ADS)
Rohde, Peter P.; Mauerer, Wolfgang; Silberhorn, Christine
We discuss the spectral structure and decomposition of multi-photon states. Ordinarily 'multi-photon states' and 'Fock states' are regarded as synonymous. However, when the spectral degrees of freedom are included this is not the case, and the class of 'multi-photon' states is much broader than the class of 'Fock' states. We discuss the criteria for a state to be considered a Fock state. We then address the decomposition of general multi-photon states into bases of orthogonal eigenmodes, building on existing multi-mode theory, and introduce an occupation number representation that provides an elegant description of such states. This representation allows us to work in bases imposed by experimental constraints, simplifying calculations in many situations. Finally we apply this technique to several example situations, which are highly relevant for state of the art experiments. These include Hong Ou Mandel interference, spectral filtering, finite bandwidth photo-detection, homodyne detection and the conditional preparation of Schrödinger kitten and Fock states. Our techniques allow for very simple descriptions of each of these examples.
Quantum optics. Quantum harmonic oscillator state synthesis by reservoir engineering.
Kienzler, D; Lo, H-Y; Keitch, B; de Clercq, L; Leupold, F; Lindenfelser, F; Marinelli, M; Negnevitsky, V; Home, J P
The robust generation of quantum states in the presence of decoherence is a primary challenge for explorations of quantum mechanics at larger scales. Using the mechanical motion of a single trapped ion, we utilize reservoir engineering to generate squeezed, coherent, and displaced-squeezed states as steady states in the presence of noise. We verify the created state by generating two-state correlated spin-motion Rabi oscillations, resulting in high-contrast measurements. For both cooling and measurement, we use spin-oscillator couplings that provide transitions between oscillator states in an engineered Fock state basis. Our approach should facilitate studies of entanglement, quantum computation, and open-system quantum simulations in a wide range of physical systems.
Optical State-of-Change Monitor for Lead-Acid Batteries
Weiss, Jonathan D.
A method and apparatus for determining the instantaneous state-of-charge of a battery in which change in composition with discharge manifests itself as a change in optical absorption. In a lead-acid battery, the sensor comprises a fiber optic system with an absorption cdl or, alternatively, an optical fiber woven into an absorbed-glass-mat battery. In a lithium-ion battery, the sensor comprises fiber optics for introducing light into the anode to monitor absorption when lithium ions are introduced.
Communication: Momentum-resolved quantum interference in optically excited surface states.
Chan, Wai-Lun; Tritsch, John; Dolocan, Andrei; Ligges, Manuel; Miaja-Avila, Luis; Zhu, X-Y
Surface states play essential roles in condensed matter physics, e.g., as model two-dimensional (2D) electron gases and as the basis for topological insulators. Here, we demonstrate quantum interference in the optical excitation of 2D surface states using the model system of C(60)/Au(111). These surface states are transiently populated and probed in a femtosecond time- and angle-resolved two-photon photoemission experiment. We observe quantum interference within the excited populations of these surface states as a function of parallel momentum vector. Such quantum interference in momentum space may allow one to control 2D transport properties by optical fields.
Nonmaximally entangled states can be better for multiple linear optical teleportation.
Modławska, Joanna; Grudka, Andrzej
We investigate multiple linear optical teleportation in the Knill-Laflamme-Milburn scheme with both maximally and nonmaximally entangled states. We show that if the qubit is teleported several times via a nonmaximally entangled state, then the errors introduced in the previous teleportations can be corrected by the errors introduced in the following teleportations. This effect is so strong that it leads to another interesting phenomenon: i.e., the total probability of successful multiple linear optical teleportation is higher for nonmaximally entangled states than maximally entangled states.
Effect of rotational-state-dependent molecular alignment on the optical dipole force
NASA Astrophysics Data System (ADS)
Kim, Lee Yeong; Lee, Ju Hyeon; Kim, Hye Ah; Kwak, Sang Kyu; Friedrich, Bretislav; Zhao, Bum Suk
The properties of molecule-optical elements such as lenses or prisms based on the interaction of molecules with optical fields depend in a crucial way on the molecular quantum state and its alignment created by the optical field. Herein, we consider the effects of state-dependent alignment in estimating the optical dipole force acting on the molecules and, to this end, introduce an effective polarizability which takes proper account of molecular alignment and is directly related to the alignment-dependent optical dipole force. We illustrate the significance of including molecular alignment in the optical dipole force by a trajectory study that compares previously used approximations with the present approach. The trajectory simulations were carried out for an ensemble of linear molecules subject to either propagating or standing-wave optical fields for a range of temperatures and laser intensities. The results demonstrate that the alignment-dependent effective polarizability can serve to provide correct estimates of the optical dipole force, on which a state-selection method applicable to nonpolar molecules could be based. We note that an analogous analysis of the forces acting on polar molecules subject to an inhomogeneous static electric field reveals a similarly strong dependence on molecular orientation.
Resonant-state expansion of dispersive open optical systems: Creating gold from sand
NASA Astrophysics Data System (ADS)
Muljarov, E. A.; Langbein, W.
A resonant-state expansion (RSE) for open optical systems with a general frequency dispersion of the permittivity is presented. The RSE of dispersive systems converts Maxwell's wave equation into a linear matrix eigenvalue problem in the basis of unperturbed resonant states, in this way numerically exactly determining all relevant eigenmodes of the optical system. The dispersive RSE is verified by application to the analytically solvable system of a sphere in vacuum, with a dispersion of the permittivity described by the Drude and Drude-Lorentz models. We calculate the optical modes converting the sphere material from gold to nondispersive sand and back to gold, and evaluate the accuracy using exact solutions.
Solid state electro-optic color filter and iris
NASA Technical Reports Server (NTRS)
The electro-optic properties of lanthanum-modified lead zirconate titanate (PLZT) ferroelectric ceramic material are evaluated when utilized as a variable density and/or spectral filter in conjunction with a television scanning system. Emphasis was placed on the development of techniques and procedures for processing the PLZT disks and for applying efficient electrode structures. A number of samples were processed using different combinations of cleaning, electrode material, and deposition process. Best overall performance resulted from the direct evaporation of gold over chrome electrodes. A ruggedized mounting holder assembly was designed, fabricated, and tested. The assembly provides electrical contacts, high voltage protection, and support for the fragile PLZT disk, and permits mounting and optical alignment of the associated polarizers. Operational measurements of a PLZT sample mounted in the holder assembly were performed in conjunction with a television camera and the associated drive circuits. The data verified achievement of the elimination of the observed white-line effect.
Optical indication for evaluation ecological state of water areas
Surin, V.G.; Goloudin, R.I.
The results of spectral measurements of reed, leaves by using a two kinds or the spectrometers at the Neva Bay and in the east part of the Gulf of Finland are discussed. It is shown that the optical properties of the coastal-aqueous vegetation depend on the presence of heavy metals in them. Key words: ecology, spectral reflectance, pollution, aqueous vegetation, remote sensing, spectrometer. 7 refs., 4 figs., 2 tabs.
Low States of Polars from CRTS Optical Light Curves
NASA Astrophysics Data System (ADS)
Santana, Joshua; Mason, Paul A.
We present a study of light curves from the 10 year baseline for 98 polars observed using the Catalina Realtime Transit Survey (CRTS). In particular we investigate the stability of high and low luminosity states, for which these highly magnetic binaries are known. We identify several classes of behavior. Some polars have stable low states, (EF Eri, AR UMa, AM Her) in which they spend considerable time. About as many dip in brightness to low states followed by quick returns, (CE Gru, BM CrB). A few like FL Cet show 3 distinctive states.
Aerosol optical properties over the midcontinental United States
NASA Technical Reports Server (NTRS)
Halthore, Rangasayi N.; Markham, Brian L.; Ferrare, Richard A.; Aro, Theo. O.
Solar and sky radiation measurements were analyzed to obtain aerosol properties such as the optical thickness and the size distribution. The measurements were conducted as part of the First International Satellite Land Surface Climatology Project Field Experiment during the second intensive field campaign (IFC) from June 25 to July 14, 1987, and the fifth IFC from July 25 to August 12, 1989, on the Konza Prairie near Manhattan, Kansas. Correlations with climatological and meteorological parameters show that during the period of observations in 1987, two types of air masses dominated the area: an air mass with low optical thickness and low temperature air associated with a northerly breeze, commonly referred to as the continental air, and an air mass with a higher optical thickness and higher temperature air associated with a southerly wind which we call 'Gulf air'. The size distributions show a predominance of the larger size particles in 'Gulf air'. Because of the presence of two contrasting air masses, correlations with parameters such as relative humidity, specific humidity, pressure, temperature, and North Star sky radiance reveal some interesting aspects. In 1989, clear distinctions between continental and Gulf air cannot be made; the reason for this will be discussed.
Race and Ethnicity, Religion Involvement, Church-based Social Support and Subjective Health in United States: A Case of Moderated Mediation
Assari, Shervin
Background: To test if social support and ethnicity mediate/moderate the association between religion involvement and subjective health in the United States. Methods: This is a secondary analysis of National Survey of American Life, 2003. Hierarchical regression was fit to a national household probability sample of adult African Americans (n = 3570), Caribbean Blacks (n = 1621), and Whites (n = 891). Frequency of church attendance, positive/negative church-based social support, ethnicity, and subjective health (overall life satisfaction and self-rated mental health) were considered as predictor, mediator, moderator and outcome, respectively. Results: Frequency of church attendance had a significant and positive association with mental health and life satisfaction among all ethnic groups. Frequency of church attendance was also correlated with positive and negative social support among all ethnic groups. Church-based social support fully mediated the association between frequency of church attendance and overall life satisfaction among African Americans but not among Caribbean Blacks, or Whites. Church-based social support, however, partially mediated the association between frequency of church attendance and overall mental health among African Americans but not among Caribbean Blacks or Whites. Conclusion: Ethnicity shapes how church-based social support mediates the association between religious involvement and subjective health. Our results showed a moderating mediation effect of ethnicity and social support on the religious involvement-subjective health linkage, in a way that it is only among African Americans that social support is a pathway for the beneficial health effect of religious involvement. PMID:23543791
Subcycle Optical Response Caused by a Terahertz Dressed State with Phase-Locked Wave Functions
NASA Astrophysics Data System (ADS)
Uchida, K.; Otobe, T.; Mochizuki, T.; Kim, C.; Yoshita, M.; Akiyama, H.; Pfeiffer, L. N.; West, K. W.; Tanaka, K.; Hirori, H.
The coherent interaction of light with matter imprints the phase information of the light field on the wave function of the photon-dressed electronic state. A driving electric field, together with a stable phase that is associated with the optical probe pulses, enables the role of the dressed state in the optical response to be investigated. We observed optical absorption strengths modulated on a subcycle time scale in a GaAs quantum well in the presence of a multicycle terahertz driving pulse using a near-infrared probe pulse. The measurements were in good agreement with the analytical formula that accounts for the optical susceptibilities caused by the dressed state of the excitons, which indicates that the output probe intensity was coherently reshaped by the excitonic sideband emissions.
Mixing of quantum states: A new route to creating optical activity.
Baimuratov, Anvar S; Tepliakov, Nikita V; Gun'ko, Yurii K; Baranov, Alexander V; Fedorov, Anatoly V; Rukhlenko, Ivan D
The ability to induce optical activity in nanoparticles and dynamically control its strength is of great practical importance due to potential applications in various areas, including biochemistry, toxicology, and pharmaceutical science. Here we propose a new method of creating optical activity in originally achiral quantum nanostructures based on the mixing of their energy states of different parities. The mixing can be achieved by selective excitation of specific states or via perturbing all the states in a controllable fashion. We analyze the general features of the so produced optical activity and elucidate the conditions required to realize the total dissymmetry of optical response. The proposed approach is applicable to a broad variety of real systems that can be used to advance chiroptical devices and methods.
Single and two-mode mechanical squeezing of an optically levitated nanodiamond via dressed-state coherence
NASA Astrophysics Data System (ADS)
Ge, Wenchao; Bhattacharya, M.
Nonclassical states of macroscopic objects are promising for ultrasensitive metrology as well as testing quantum mechanics. In this work, we investigate dissipative mechanical quantum state engineering in an optically levitated nanodiamond. First, we study single-mode mechanical squeezed states by magnetically coupling the mechanical motion to a dressed three-level system provided by a nitrogen-vacancy center in the nanoparticle. Quantum coherence between the dressed levels is created via microwave fields to induce a two-phonon transition, which results in mechanical squeezing. Remarkably, we find that in ultrahigh vacuum quantum squeezing is achievable at room temperature with feedback cooling. For moderate vacuum, quantum squeezing is possible with cryogenic temperature. Second, we present a setup for two mechanical modes coupled to the dressed three levels, which results in two-mode squeezing analogous to the mechanism of the single-mode case. In contrast to previous works, our study provides a deterministic method for engineering macroscopic squeezed states without the requirement for a cavity.
Optical description of solid-state dye-sensitized solar cells. I. Measurement of layer optical properties
Moule, Adam J.; Snaith, Henry J.; Kaiser, Markus; Klesper, Heike; Meerholz, Klaus; Huang, David M.; Graetzel, Michael
The efficiency of a photovoltaic device is limited by the portion of solar energy that can be captured. We discuss how to measure the optical properties of the various layers in solid-state dye-sensitized solar cells (SDSC). We use spectroscopic ellipsometry to determine the complex refractive index of each of the various layers in a SDSC. Each of the ellipsometry fits is used to calculate a transmission spectrum that is compared to a measured transmission spectrum. The complexities of pore filling on the fitting of the ellipsometric data are discussed. Scanning electron microscopy and energy dispersive x-ray spectroscopy is shown to be an effective method for determining pore filling in SDSC layers. Accurate effective medium optical constants for each layer are presented and the material limits under which these optical constants can be used are discussed.
Tailoring cyanine dark states for improved optically modulated fluorescence recovery.
Mahoney, Daniel P; Owens, Eric A; Fan, Chaoyang; Hsiang, Jung-Cheng; Henary, Maged M; Dickson, Robert M
Cyanine dyes are well-known for their bright fluorescence and utility in biological imaging. However, cyanines also readily photoisomerize to produce nonemissive dark states. Co-illumination with a secondary, red-shifted light source on-resonance with the longer wavelength absorbing dark state reverses the photoisomerization and returns the cyanine dye to the fluorescent manifold, increasing steady-state fluorescence intensity. Modulation of this secondary light source dynamically alters emission intensity, drastically improving detection sensitivity and facilitating fluorescence signals to be recovered from an otherwise overwhelming background. Red and near-IR emitting cyanine derivatives have been synthesized with varying alkyl chain lengths and halogen substituents to alter dual-laser fluorescence enhancement. Photophysical properties and enhancement with dual laser modulation were coupled with density functional calculations to characterize substituent effects on dark state photophysics, potentially improving detection in high background biological environments.
Tailoring Cyanine Dark States for Improved Optically Modulated Fluorescence Recovery
Mahoney, Daniel P.; Owens, Eric A.; Fan, Chaoyang; Hsiang, Jung-Cheng; Henary, Maged M.; Dickson, Robert M.
Cyanine dyes are well known for their bright fluorescence and utility in biological imaging. Yet, cyanines also readily photoisomerize to produce non-emissive dark states. Co-illumination with a secondary, red-shifted light source on-resonance with the longer wavelength absorbing dark state reverses the photoisomerization and returns the cyanine dye to the fluorescent manifold, increasing steady-state fluorescence intensity. Modulation of this secondary light source dynamically alters emission intensity, drastically improving detection sensitivity and facilitating fluorescence signals to be recovered from otherwise overwhelming background. Red and near-IR emitting cyanine derivatives have been synthesized with varying alkyl chain lengths and halogen substituents to alter dual-laser fluorescence enhancement. Photophysical properties and enhancement with dual laser modulation were coupled with density functional calculations to characterize substituent effects on dark state photophysics, potentially improving detection in high background biological environments. PMID:25763888
Nonclassical states of the second optical harmonic in the presence of self-action
NASA Technical Reports Server (NTRS)
Chirkin, A. S.; Korolkova, N. V.
The quantum theory of coherent radiation frequency doubling in crystals with quadratic and cubic optical nonlinearities is developed. The possibility of producing the quadrature-squeezed state of the second harmonic (SH) field is shown. The nonclassical SH states arise due to self-action effect.
Optical fingerprint of dark 2p-states in transition metal dichalcogenides
NASA Astrophysics Data System (ADS)
Berghäuser, Gunnar; Knorr, Andreas; Malic, Ermin
Atomically thin transition metal dichalcogenides exhibit a remarkably strong Coulomb interaction. This results in a fascinating many-particle physics including a variety of bright and dark excitonic states that determine optical and electronic properties of these materials. So far, the impact of dark states has remained literally in the dark to a large extent, since a measurement of these optically forbidden states is very challenging. Here we demonstrate a strategy to measure a direct fingerprint of dark states even in standard linear absorption spectroscopy. We present a microscopic study on bright and dark higher excitonic states in the presence of disorder for the exemplary material of tungsten disulfide (WS2). We show that the geometric phase cancels the degeneration of 2s and 2p states and that a significant disorder-induced coupling of these bright and dark states offers a strategy to circumvent optical selection rules. As a proof, we show a clear fingerprint of dark 2p states in the absorption spectrum of WS2. The predicted softening of optical selection rules through exciton-disorder coupling is of general nature and therefore applicable to related two-dimensional semiconductors.
Magneto-optical contrast in liquid-state optically detected NMR spectroscopy
Pagliero, Daniela; Meriles, Carlos A.
We use optical Faraday rotation (OFR) to probe nuclear spins in real time at high-magnetic field in a range of diamagnetic sample fluids. Comparison of OFR-detected NMR spectra reveals a correlation between the relative signal amplitude and the fluid Verdet constant, which we interpret as a manifestation of the variable detuning between the probe beam and the sample optical transitions. The analysis of chemical-shift-resolved, optically detected spectra allows us to set constraints on the relative amplitudes of hyperfine coupling constants, both for protons at chemically distinct sites and other lower-gyromagnetic-ratio nuclei including carbon, fluorine, and phosphorous. By considering a model binary mixture we observe a complex dependence of the optical response on the relative concentration, suggesting that the present approach is sensitive to the solvent-solute dynamics in ways complementary to those known in inductive NMR. Extension of these experiments may find application in solvent suppression protocols, sensitivity-enhanced NMR of metalloproteins in solution, the investigation of solvent-solute interactions, or the characterization of molecular orbitals in diamagnetic systems. PMID:22100736
Arbitrarily complete Bell-state measurement using only linear optical elements
Grice, W. P.
A complete Bell-state measurement is not possible using only linear-optic elements, and most schemes achieve a success rate of no more than 50%, distinguishing, for example, two of the four Bell states but returning degenerate results for the other two. It is shown here that the introduction of a pair of ancillary entangled photons improves the success rate to 75%. More generally, the addition of 2{sup N}-2 ancillary photons yields a linear-optic Bell-state measurement with a success rate of 1-1/2{sup N}.
Possibility of triple magic trapping of clock and Rydberg states of divalent atoms in optical lattices
NASA Astrophysics Data System (ADS)
Topcu, T.; Derevianko, A.
We predict the possibility of 'triply magic' optical lattice trapping of neutral divalent atoms. In such a lattice, the {}1{{{S}}}0 and {}3{{{P}}}0 clock states and an additional Rydberg state experience identical optical potentials, fully mitigating detrimental effects of the motional decoherence. In particular, we show that this triply magic trapping condition can be satisfied for Yb atom at optical wavelengths and for various other divalent systems (Ca, Mg, Hg and Sr) in the UV region. We assess the quality of triple magic trapping conditions by estimating the probability of excitation out of the motional ground state as a result of the excitations between the clock and the Rydberg states. We also calculate trapping laser-induced photoionization rates of divalent Rydberg atoms at magic frequencies. We find that such rates are below the radiative spontaneous-emission rates, due to the presence of Cooper minima in photoionization cross-sections.
The Development of Replicated Optical Integral Field Spectrographs and their Application to the Study of Lyman-alpha Emission at Moderate Redshifts
NASA Astrophysics Data System (ADS)
Chonis, Taylor Steven
volume phase holographic (VPH) diffraction gratings for VIRUS is presented, which highlights the challenge and success associated with producing of a very large number of highly customized optical elements whose performance is crucial to meeting the efficiency requirements of the spectrograph system. To accommodate VIRUS, the HET is undergoing a substantial wide-field upgrade to increase its field of view to 22' in diameter. The previous HET facility Low Resolution Spectrograph (LRS), which was directly fed by the telescope's previous spherical aberration corrector, must be removed from the prime focus instrument package as a result of the telescope upgrades and instead be fiber-coupled to the telescope focal plane. For a similar cost as modifying LRS to accommodate these changes, a new second generation instrument (LRS2) will be based on the VIRUS unit spectrograph. The design, operational concept, construction, and laboratory testing and characterization of LRS2 is the primary focus of this dissertation, which highlights the benefits of leveraging the large engineering investment, economies of scale, and laboratory and observatory infrastructure associated with the massively replicated VIRUS instrument. LRS2 will provide integral field spectroscopy for a seeing-limited field of 12" x 6". The multiplexed VIRUS framework facilitates broad wavelength coverage from 370 nm to 1.0 mum spread between two dual-channel spectrographs at a moderate spectral resolving power of R ≈ 2000. The design departures from VIRUS are presented, including the novel integral field unit, VPH grism dispersers, and various optical changes for accommodating the broadband wavelength coverage. Laboratory testing has verified that LRS2 largely meets its image quality specification and is nearly ready for delivery to the HET where its final verification and validation tasks will be executed. LRS2 will enable the continuation of most legacy LRS science programs and provide improved capability for
"I am resting but rest less well with you." The moderating effect of anxious attachment style on alpha power during EEG resting state in a social context.
Verbeke, Willem J M I; Pozharliev, Rumen; Van Strien, Jan W; Belschak, Frank; Bagozzi, Richard P
We took EEG recordings to measure task-free resting-state cortical brain activity in 35 participants under two conditions, alone (A) or together (T). We also investigated whether psychological attachment styles shape human cortical activity differently in these two settings. The results indicate that social context matters and that participants' cortical activity is moderated by the anxious, but not avoidant attachment style. We found enhanced alpha, beta and theta band activity in the T rather than the A resting-state condition, which was more pronounced in posterior brain regions. We further found a positive correlation between anxious attachment style and enhanced alpha power in the T vs. A condition over frontal and parietal scalp regions. There was no significant correlation between the absolute powers registered in the other two frequency bands and the participants' anxious attachment style.
Effect of additional optical pumping injection into the ground-state ensemble on the gain and the phase recovery acceleration of quantum-dot semiconductor optical amplifiers
NASA Astrophysics Data System (ADS)
Kim, Jungho
The effect of additional optical pumping injection into the ground-state ensemble on the ultrafast gain and the phase recovery dynamics of electrically-driven quantum-dot semiconductor optical amplifiers is numerically investigated by solving 1088 coupled rate equations. The ultrafast gain and the phase recovery responses are calculated with respect to the additional optical pumping power. Increasing the additional optical pumping power can significantly accelerate the ultrafast phase recovery, which cannot be done by increasing the injection current density.
State anxiety as a moderator of real world grocery shopping performance among people with serious mental illness.
Racette, Elise H; Fowler, Christopher A; Rempfer, Melisa V
Anxiety is frequently overlooked as a factor when examining task performance among individuals with serious mental illness. Given the known effects of anxiety on performance in general populations, it is important to examine anxiety and performance within a serious mental illness population. This study examined state anxiety during a grocery-shopping task among 106 individuals diagnosed with a serious mental illness. Results indicate that state anxiety may impact task performance through its relationship with knowledge about grocery-shopping skills. These data suggest the need to examine further the impact of anxiety on task performance in serious mental illness. Furthermore, the identification and treatment of anxiety in persons with SMI may serve to improve functional outcomes and rehabilitation efforts.
Quasi-optical solid-state power combining for millimeter-wave active seeker applications
NASA Astrophysics Data System (ADS)
Halladay, R. H.; Terrill, S. D.; Bowling, D. R.; Gagnon, D. R.
Consideration is given to quasi-optical power combining techniques, state-of-the-art demonstrated performance, and system issues as they apply to endoatmospheric homing seeker insertion. Quasi-optical power combining is based on combining microwave and millimeter-wave solid-state device power in space through the use of antennas and lenses. It is concluded that quasi-optical power combining meets the severe electrical requirements and packaging constraints of active MMW seekers for endoatmospheric hit-to-kill missiles. The approach provides the possibility of wafer-scale integration of major components for low cost production and offers high reliability. Critical issues include thermal loading and system integration, which must be resolved before the quasi-optical power combining technology will be applied to an active MMW seeker.
Optical limiting and excited-state absorption in fullerene solutions and doped glasses
McBranch, D.; Smilowitz, L.; Klimov, V.
We report the ground state and excited state optical absorption spectra in the visible and near infrared for several substituted fullerenes and higher fullerenes in toluene solutions. Based on these measurements, broadband predictions of the optical limiting performance of these molecules can be deduced. These predictions are then tested at 532 to 700 nm in intensity-dependent transmission measurements. We observe optical limiting in all fullerenes measured; higher fullerenes show the greatest potential for limiting in the near infrared (650-1000 nm), while substituted C{sub 60} shows optimal limiting in the visible (450-700 nm). We observe dramatically reduced limiting for solid forms of C{sub 60} (thin films and C{sub 60}-doped porous glasses), indicating that efficient optical limiting in fullerenes requires true molecular solutions.
What students think they feel differs from what they really feel--academic self-concept moderates the discrepancy between students' trait and state emotional self-reports.
Bieg, Madeleine; Goetz, Thomas; Lipnevich, Anastasiya A
This study investigated whether there is a discrepancy pertaining to trait and state academic emotions and whether self-concept of ability moderates this discrepancy. A total of 225 secondary school students from two different countries enrolled in grades 8 and 11 (German sample; n = 94) and grade 9 (Swiss sample; n = 131) participated. Students' trait academic emotions of enjoyment, pride, anger, and anxiety in mathematics were assessed with a self-report questionnaire, whereas to assess their state academic emotions experience-sampling method was employed. The results revealed that students' scores on the trait assessment of emotions were generally higher than their scores on the state assessment. Further, as expected, students' academic self-concept in the domain of mathematics was shown to partly explain the discrepancy between scores on trait and state emotions. Our results indicate that there is a belief-driven discrepancy between what students think they feel (trait assessment) and what they really feel (state assessment). Implications with regard to the assessment of self-reported emotions in future studies and practical implications for the school context are discussed.
Autonomous regulation mode moderates the effect of actual physical activity on affective states: an ambulant assessment approach to the role of self-determination.
Kanning, Martina; Ebner-Priemer, Ulrich; Brand, Ralf
Studies have shown that physical activity influences affective states. However, studies have seldom depicted these associations in ongoing real-life situations, and there is no investigation showing that motivational states (i.e., more or less autonomously regulated) would moderate these effects in situ. To investigate the interaction of autonomous regulation and actual physical activity (aPA) with affective states, we use an ambulatory assessment approach. The participants were 44 university students (mean age: 26.2 ± 3.2 years). We assessed aPA through 24-hr accelerometry and affective states and autonomous regulation via electronic diaries. Palmtop devices prompted subjects every 45 min during a 14-hr daytime period. We performed hierarchical multilevel analyses. Both aPA and autonomous regulation significantly influenced affective states. The interaction was significant for two affects. The higher the volume of aPA and thereby the more autonomously regulated the preceding bout of aPA was, the more our participants felt energized (r = .16) but agitated (r = -.18).
What Students Think They Feel Differs from What They Really Feel – Academic Self-Concept Moderates the Discrepancy between Students' Trait and State Emotional Self-Reports
Bieg, Madeleine; Goetz, Thomas; Lipnevich, Anastasiya A.
This study investigated whether there is a discrepancy pertaining to trait and state academic emotions and whether self-concept of ability moderates this discrepancy. A total of 225 secondary school students from two different countries enrolled in grades 8 and 11 (German sample; n = 94) and grade 9 (Swiss sample; n = 131) participated. Students' trait academic emotions of enjoyment, pride, anger, and anxiety in mathematics were assessed with a self-report questionnaire, whereas to assess their state academic emotions experience-sampling method was employed. The results revealed that students' scores on the trait assessment of emotions were generally higher than their scores on the state assessment. Further, as expected, students' academic self-concept in the domain of mathematics was shown to partly explain the discrepancy between scores on trait and state emotions. Our results indicate that there is a belief-driven discrepancy between what students think they feel (trait assessment) and what they really feel (state assessment). Implications with regard to the assessment of self-reported emotions in future studies and practical implications for the school context are discussed. PMID:24647760
Optically induced rotation of Rayleigh particles by vortex beams with different states of polarization
NASA Astrophysics Data System (ADS)
Li, Manman; Yan, Shaohui; Yao, Baoli; Liang, Yansheng; Lei, Ming; Yang, Yanlong
Optical vortex beams carry optical orbital angular momentum (OAM) and can induce an orbital motion of trapped particles in optical trapping. We show that the state of polarization (SOP) of vortex beams will affect the details of this optically induced orbital motion to some extent. Numerical results demonstrate that focusing the vortex beams with circular, radial or azimuthal polarizations can induce a uniform orbital motion on a trapped Rayleigh particle, while in the focal field of the vortex beam with linear polarization the particle experiences a non-uniform orbital motion. Among the formers, the vortex beam with circular polarization induces a maximum optical torque on the particle. Furthermore, by varying the topological charge of the vortex beams, the vortex beam with circular polarization gives rise to an optimum torque superior to those given by the other three vortex beams. These facts suggest that the circularly polarized vortex beam is more suitable for rotating particles.
Role of photonic angular momentum states in nonreciprocal diffraction from magneto-optical cylinder arrays
Guo, Tian-Jing; Wu, Li-Ting; Yang, Mu; Guo, Rui-Peng; Cui, Hai-Xu; Chen, Jing
Optical eigenstates in a concentrically symmetric resonator are photonic angular momentum states (PAMSs) with quantized optical orbital angular momentums (OAMs). Nonreciprocal optical phenomena can be obtained if we lift the degeneracy of PAMSs. In this article, we provide a comprehensive study of nonreciprocal optical diffraction of various orders from a magneto-optical cylinder array. We show that nonreciprocal diffraction can be obtained only for these nonzero orders. Role of PAMSs, the excitation of which is sensitive to the directions of incidence, applied magnetic field, and arrangement of the cylinders, are studied. Some interesting phenomena such as a dispersionless quasi-omnidirectional nonreciprocal diffraction and spikes associated with high-OAM PAMSs are present and discussed.
An investigation of optical feedback to extend the frequency response of solid-state detector systems
NASA Technical Reports Server (NTRS)
Katzberg, S. J.
A primary limitation of many solid-state photodetectors used in electro-optical systems such as the facsimile camera is their slow response in converting light intensities into electrical signals. An optical feedback technique is presented which can extend the frequency response of systems that use these detectors by orders of magnitude without significantly degrading their signal-to-noise performance. This technique is analyzed to predict improvement, implemented, and evaluated to verify analytical results.
Optical Tamm state and giant asymmetry of light transmission through an array of nanoholes
NASA Astrophysics Data System (ADS)
Klimov, Vasily V.; Treshin, Ilya V.; Shalin, Alexander S.; Melentiev, Pavel N.; Kuzin, Artur A.; Afanasiev, Anton E.; Balykin, Victor I.
We have predicted theoretically and verified experimentally the occurrence of a giant asymmetry of the transmission of arbitrarily polarized light propagating through a linear nonmagnetic optical system that consists of a metal film with a two-dimensional array of nanoholes in it and that is deposited on the surface of a planar dielectric photonic crystal. The asymmetry of the light transmission is caused by two factors: (i) the excitation of an optical Tamm state in the system, and (ii) the existence of many secondary lobes in the diffraction pattern. Our results are of interest for the development of efficient planar optical diodelike systems and related nanophotonic devices.
Superdense Coding over Optical Fiber Links with Complete Bell-State Measurements
Williams, Brian P.; Sadlier, Ronald J.; Humble, Travis S.
Adopting quantum communication to modern networking requires transmitting quantum information through a fiber-based infrastructure. In this paper, we report the first demonstration of superdense coding over optical fiber links, taking advantage of a complete Bell-state measurement enabled by time-polarization hyperentanglement, linear optics, and common single-photon detectors. Finally, we demonstrate the highest single-qubit channel capacity to date utilizing linear optics, 1.665 ± 0.018, and we provide a full experimental implementation of a hybrid, quantum-classical communication protocol for image transfer.
New optical diagnostics for equation of state experiments on the Janus laser
Spaulding, D. K.; Jeanloz, R.; Hicks, D. G.; Smith, R. F.; Eggert, J. H.; Collins, G. W.; McWilliams, R. S.
We describe the configuration of two new optical diagnostics for laser-driven dynamic-compression experiments to multi-Mbar pressures. A streaked optical pyrometer (SOP) has been developed to provide temporally and spatially-resolved records of the thermal emission from shock-compressed samples. In addition, temporally-resolved broadband reflectivity is measured between 532 and {approx}850 nm by supercontinuum generation in an optical fiber. These new tools expand capabilities to probe the thermal and electronic states of matter at high pressures and temperatures using the Lawrence Livermore National Laboratory's Janus laser.
Circularly polarized near-field optical mapping of spin-resolved quantum Hall chiral edge states.
Mamyouda, Syuhei; Ito, Hironori; Shibata, Yusuke; Kashiwaya, Satoshi; Yamaguchi, Masumi; Akazaki, Tatsushi; Tamura, Hiroyuki; Ootuka, Youiti; Nomura, Shintaro
We have successfully developed a circularly polarized near-field scanning optical microscope (NSOM) that enables us to irradiate circularly polarized light with spatial resolution below the diffraction limit. As a demonstration, we perform real-space mapping of the quantum Hall chiral edge states near the edge of a Hall-bar structure by injecting spin polarized electrons optically at low temperature. The obtained real-space mappings show that spin-polarized electrons are injected optically to the two-dimensional electron layer. Our general method to locally inject spins using a circularly polarized NSOM should be broadly applicable to characterize a variety of nanomaterials and nanostructures.
Superdense Coding over Optical Fiber Links with Complete Bell-State Measurements
NASA Astrophysics Data System (ADS)
Williams, Brian P.; Sadlier, Ronald J.; Humble, Travis S.
Adopting quantum communication to modern networking requires transmitting quantum information through a fiber-based infrastructure. We report the first demonstration of superdense coding over optical fiber links, taking advantage of a complete Bell-state measurement enabled by time-polarization hyperentanglement, linear optics, and common single-photon detectors. We demonstrate the highest single-qubit channel capacity to date utilizing linear optics, 1.665 ±0.018 , and we provide a full experimental implementation of a hybrid, quantum-classical communication protocol for image transfer.
Generation of concatenated Greenberger-Horne-Zeilinger-type entangled coherent state based on linear optics
NASA Astrophysics Data System (ADS)
Guo, Rui; Zhou, Lan; Gu, Shi-Pu; Wang, Xing-Fu; Sheng, Yu-Bo
The concatenated Greenberger-Horne-Zeilinger (C-GHZ) state is a new type of multipartite entangled state, which has potential application in future quantum information. In this paper, we propose a protocol of constructing arbitrary C-GHZ entangled state approximatively. Different from previous protocols, each logic qubit is encoded in the coherent state. This protocol is based on the linear optics, which is feasible in experimental technology. This protocol may be useful in quantum information based on the C-GHZ state.
Interleukin-1 antagonism moderates the inflammatory state associated with Type 1 diabetes during clinical trials conducted at disease onset.
Cabrera, Susanne M; Wang, Xujing; Chen, Yi-Guang; Jia, Shuang; Kaldunski, Mary L; Greenbaum, Carla J; Mandrup-Poulsen, Thomas; Hessner, Martin J
It was hypothesized that IL-1 antagonism would preserve β-cell function in new onset Type 1 diabetes (T1D). However, the Anti-Interleukin-1 in Diabetes Action (AIDA) and TrialNet Canakinumab (TN-14) trials failed to show efficacy of IL-1 receptor antagonist (IL-1Ra) or canakinumab, as measured by stimulated C-peptide response. Additional measures are needed to define immune state changes associated with therapeutic responses. Here, we studied these trial participants with plasma-induced transcriptional analysis. In blinded analyses, 70.2% of AIDA and 68.9% of TN-14 participants were correctly called to their treatment arm. While the transcriptional signatures from the two trials were distinct, both therapies achieved varying immunomodulation consistent with IL-1 inhibition. On average, IL-1 antagonism resulted in modest normalization relative to healthy controls. At endpoint, signatures were quantified using a gene ontology-based inflammatory index, and an inverse relationship was observed between measured inflammation and stimulated C-peptide response in IL-1Ra- and canakinumab-treated patients. Cytokine neutralization studies showed that IL-1α and IL-1β additively contribute to the T1D inflammatory state. Finally, analyses of baseline signatures were indicative of later therapeutic response. Despite the absence of clinical efficacy by IL-1 antagonist therapy, transcriptional analysis detected immunomodulation and may yield new insight when applied to other clinical trials.
Optical Characterization of Deep-Space Object Rotation States
characterize non-resolvable object rotation states, focusing on objects well above low- Earth orbit altitudes. 3 OBSERVATIONS OF NON-RESOLVED ROTATING...OBJECTS This analysis focuses on broad-band temporal photometry of Earth -orbiting satellites (i.e., time-series measurements of whole-object...order. Upper-stages from rockets that have launched satellites into orbit represent one of the most common types of rotating object in Earth orbit
Optical Pulse Interactions in Nonlinear Excited State Materials
for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching data sources...Paperwork Reduction Project (0704-0188) Washington, DC 20503. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1 . REPORT DATE (DD-MM-YYYY) 14...Excited State Materials 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-04- 1 -0219 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Potasek
Unconventional fermionic pairing states in a monochromatically tilted optical lattice
NASA Astrophysics Data System (ADS)
Nocera, A.; Polkovnikov, A.; Feiguin, A. E.
We study the one-dimensional attractive fermionic Hubbard model under the influence of periodic driving with the time-dependent density matrix renormalization group method. We show that the system can be driven into an unconventional pairing state characterized by a condensate made of Cooper pairs with a finite center-of-mass momentum similar to a Fulde-Ferrell state. We obtain results both in the laboratory and the rotating reference frames demonstrating that the momentum of the condensate can be finely tuned by changing the ratio between the amplitude and the frequency of the driving. In particular, by quenching this ratio to the value corresponding to suppression of the tunneling and the Coulomb interaction strength to zero, we are able to "freeze" the condensate. We finally study the effects of different initial conditions and compare our numerical results to those obtained from a time-independent Floquet theory in the large frequency regime. Our work offers the possibility of engineering and controlling unconventional pairing states in fermionic condensates.
Unconventional fermionic pairing states in a monochromatically tilted optical lattice
Nocera, Alberto; Polkovnikov, Anatoli; Feiguin, Adrian E.
We study the one-dimensional attractive fermionic Hubbard model under the influence of periodic driving with the time-dependent density matrix renormalization group method. We show that the system can be driven into an unconventional pairing state characterized by a condensate made of Cooper pairs with a finite center-of-mass momentum similar to a Fulde-Ferrell state. We obtain results both in the laboratory and the rotating reference frames demonstrating that the momentum of the condensate can be finely tuned by changing the ratio between the amplitude and the frequency of the driving. In particular, by quenching this ratio to the value corresponding tomore » suppression of the tunneling and the Coulomb interaction strength to zero, we are able to "freeze" the condensate. We finally study the effects of different initial conditions and compare our numerical results to those obtained from a time-independent Floquet theory in the large frequency regime. Lastly, our work offers the possibility of engineering and controlling unconventional pairing states in fermionic condensates.« less
Evidence for the conjecture that sampling generalized cat states with linear optics is hard
NASA Astrophysics Data System (ADS)
Rohde, Peter P.; Motes, Keith R.; Knott, Paul A.; Fitzsimons, Joseph; Munro, William J.; Dowling, Jonathan P.
Boson sampling has been presented as a simplified model for linear optical quantum computing. In the boson-sampling model, Fock states are passed through a linear optics network and sampled via number-resolved photodetection. It has been shown that this sampling problem likely cannot be efficiently classically simulated. This raises the question as to whether there are other quantum states of light for which the equivalent sampling problem is also computationally hard. We present evidence, without using a full complexity proof, that a very broad class of quantum states of light—arbitrary superpositions of two or more coherent states—when evolved via passive linear optics and sampled with number-resolved photodetection, likely implements a classically hard sampling problem.
An optical-optical double resonance experiment in LiH molecules: Lifetime measurements in the C state
NASA Astrophysics Data System (ADS)
Bouloufa, N.; Cabaret, L.; Luc, P.; Vetter, R.; Luh, W. T.
An optical-optical double resonance sub-Doppler experiment is used to measure short nonradiative lifetimes in the C 1Σ+ state of LiH. These lifetimes are expected to result from the strong electronic interaction between the C 1Σ+ state and the continuum of the A 1Σ+ state and to vary with the vibrational quantum number, from nanoseconds to milliseconds [F. Gemperlé and F. X. Gadéa, J. Chem. Phys. 110, 11197 (1999)]. The experimental setup combines a molecular beam of LiH, a first cw laser beam locked to a given A-X absorption line, and a second cw laser beam scanned over C-A absorption profiles. Analysis of these absorption profiles in terms of Voigt profiles shows that their Lorentzian components significantly vary with the vibrational quantum numbers of the C state. Nonradiative decay rates deduced this way are systematically larger than the calculated ones but their variations are similar. Coherent saturation effects cannot be invoked to explain this discrepancy.
Resource-efficient generation of linear cluster states by linear optics with postselection
Uskov, D. B.; Alsing, P. M.; Fanto, M. L.; ...
Here we report on theoretical research in photonic cluster-state computing. Finding optimal schemes of generating non-classical photonic states is of critical importance for this field as physically implementable photon-photon entangling operations are currently limited to measurement-assisted stochastic transformations. A critical parameter for assessing the efficiency of such transformations is the success probability of a desired measurement outcome. At present there are several experimental groups that are capable of generating multi-photon cluster states carrying more than eight qubits. Separate photonic qubits or small clusters can be fused into a single cluster state by a probabilistic optical CZ gate conditioned on simultaneousmore » detection of all photons with 1/9 success probability for each gate. This design mechanically follows the original theoretical scheme of cluster state generation proposed more than a decade ago by Raussendorf, Browne, and Briegel. The optimality of the destructive CZ gate in application to linear optical cluster state generation has not been analyzed previously. Our results reveal that this method is far from the optimal one. Employing numerical optimization we have identified that the maximal success probability of fusing n unentangled dual-rail optical qubits into a linear cluster state is equal to 1/2n-1; an m-tuple of photonic Bell pair states, commonly generated via spontaneous parametric down-conversion, can be fused into a single cluster with the maximal success probability of 1/4m-1.« less
Resource-efficient generation of linear cluster states by linear optics with postselection
Uskov, D. B.; Alsing, P. M.; Fanto, M. L.; Kaplan, L.; Kim, R.; Szep, A.; Smith, A. M.
Here we report on theoretical research in photonic cluster-state computing. Finding optimal schemes of generating non-classical photonic states is of critical importance for this field as physically implementable photon-photon entangling operations are currently limited to measurement-assisted stochastic transformations. A critical parameter for assessing the efficiency of such transformations is the success probability of a desired measurement outcome. At present there are several experimental groups that are capable of generating multi-photon cluster states carrying more than eight qubits. Separate photonic qubits or small clusters can be fused into a single cluster state by a probabilistic optical CZ gate conditioned on simultaneous detection of all photons with 1/9 success probability for each gate. This design mechanically follows the original theoretical scheme of cluster state generation proposed more than a decade ago by Raussendorf, Browne, and Briegel. The optimality of the destructive CZ gate in application to linear optical cluster state generation has not been analyzed previously. Our results reveal that this method is far from the optimal one. Employing numerical optimization we have identified that the maximal success probability of fusing n unentangled dual-rail optical qubits into a linear cluster state is equal to 1/2n-1; an m-tuple of photonic Bell pair states, commonly generated via spontaneous parametric down-conversion, can be fused into a single cluster with the maximal success probability of 1/4m-1.
The local density of optical states of a metasurface
Lunnemann, Per; Koenderink, A. Femius
While metamaterials are often desirable for near-field functions, such as perfect lensing, or cloaking, they are often quantified by their response to plane waves from the far field. Here, we present a theoretical analysis of the local density of states near lattices of discrete magnetic scatterers, i.e., the response to near field excitation by a point source. Based on a pointdipole theory using Ewald summation and an array scanning method, we can swiftly and semi-analytically evaluate the local density of states (LDOS) for magnetoelectric point sources in front of an infinite two-dimensional (2D) lattice composed of arbitrary magnetoelectric dipole scatterers. The method takes into account radiation damping as well as all retarded electrodynamic interactions in a self-consistent manner. We show that a lattice of magnetic scatterers evidences characteristic Drexhage oscillations. However, the oscillations are phase shifted relative to the electrically scattering lattice consistent with the difference expected for reflection off homogeneous magnetic respectively electric mirrors. Furthermore, we identify in which source-surface separation regimes the metasurface may be treated as a homogeneous interface, and in which homogenization fails. A strong frequency and in-plane position dependence of the LDOS close to the lattice reveals coupling to guided modes supported by the lattice. PMID:26868601
Discriminating quantum-optical beam-splitter channels with number-diagonal signal states: Applications to quantum reading and target detection
Nair, Ranjith
We consider the problem of distinguishing, with minimum probability of error, two optical beam-splitter channels with unequal complex-valued reflectivities using general quantum probe states entangled over M signal and M' idler mode pairs of which the signal modes are bounced off the beam splitter while the idler modes are retained losslessly. We obtain a lower bound on the output state fidelity valid for any pure input state. We define number-diagonal signal (NDS) states to be input states whose density operator in the signal modes is diagonal in the multimode number basis. For such input states, we derive series formulas for the optimal error probability, the output state fidelity, and the Chernoff-type upper bounds on the error probability. For the special cases of quantum reading of a classical digital memory and target detection (for which the reflectivities are real valued), we show that for a given input signal photon probability distribution, the fidelity is minimized by the NDS states with that distribution and that for a given average total signal energy N{sub s}, the fidelity is minimized by any multimode Fock state with N{sub s} total signal photons. For reading of an ideal memory, it is shown that Fock state inputs minimize the Chernoff bound. For target detection under high-loss conditions, a no-go result showing the lack of appreciable quantum advantage over coherent state transmitters is derived. A comparison of the error probability performance for quantum reading of number state and two-mode squeezed vacuum state (or EPR state) transmitters relative to coherent state transmitters is presented for various values of the reflectances. While the nonclassical states in general perform better than the coherent state, the quantitative performance gains differ depending on the values of the reflectances. The experimental outlook for realizing nonclassical gains from number state transmitters with current technology at moderate to high values of the
Improved Fluorescent Protein Contrast and Discrimination by Optically Controlling Dark State Lifetimes.
Chen, Yen-Cheng; Dickson, Robert M
Modulation and optical control of photoswitchable fluorescent protein (PS-FP) dark state lifetimes drastically improves sensitivity and selectivity in fluorescence imaging. The dark state population of PS-FPs generates an out-of-phase fluorescence component relative to the sinusoidally modulated 488 nm laser excitation. Because this apparent phase advanced emission results from slow recovery to the fluorescent manifold, we hasten recovery and, therefore, modulation frequency by varying coillumination intensity at 405 nm. As 405 nm illumination regenerates the fluorescent ground state more rapidly than via thermal recovery, we experimentally demonstrate that secondary illumination can control PS-FPs dark state lifetime to act as an additional dimension for discriminating spatially and spectrally overlapping emitters. This experimental combination of out of phase imaging after optical modulation (OPIOM) and synchronously amplified fluorescence image recovery (SAFIRe) optically controls the fluorescent protein dark state lifetimes for improved time resolution, with the resulting modulation-based selective signal recovery being quantitatively modeled. The combined experimental results and quantitative numerical simulations further demonstrate the potential of SAFIRe-OPIOM for wide-field biological imaging with improved speed, sensitivity, and optical resolution over other modulation-based fluorescence microscopies.
Measurement-based generation of shaped single photons and coherent state superpositions in optical cavities
NASA Astrophysics Data System (ADS)
Lecamwasam, Ruvindha L.; Hush, Michael R.; James, Matthew R.; Carvalho, André R. R.
We propose related schemes to generate arbitrarily shaped single photons, i.e., photons with an arbitrary temporal profile, and coherent state superpositions using simple optical elements. The first system consists of two coupled cavities, a memory cavity and a shutter cavity, containing a second-order optical nonlinearity and electro-optic modulator (EOM), respectively. Photodetection events of the shutter cavity output herald preparation of a single photon in the memory cavity, which may be stored by immediately changing the optical length of the shutter cavity with the EOM after detection. On-demand readout of the photon, with arbitrary shaping, can be achieved through modulation of the EOM. The second scheme consists of a memory cavity with two outputs, which are interfered, phase shifted, and measured. States that closely approximate a coherent state superposition can be produced through postselection for sequences of detection events, with more photon detection events leading to a larger superposition. We furthermore demonstrate that no-knowledge feedback can be easily implemented in this system and used to preserve the superposition state, as well as provide an extra control mechanism for state generation.
Sumner, L W
This essay offers a moderate view of abortion that imposes a time limit for unrestricted abortion and specific indications for later abortions. The introduction notes that the discussion will provide a defense for this policy based on a moral analysis but that other options for moderates, especially options provided by freestanding views (the defense of which does not rest on any prior commitment about the morality of abortion), will also be considered. The next section considers the moral status of the fetus grounded in a criterion of moral standing that stipulates the necessary characteristics to achieve moral standing. This discussion concludes that a fetus acquires moral standing only when it becomes sentient. Section 3 moves the argument from ethics to politics to prove that a moderate policy must place no limitations on abortion before the time the fetus becomes sentient because before that time the fetus has no interest for the state to protect. The final section notes that some pro-choice advocates may be happier with the moderate policy proposed than with its controversial defense based on the moral status of the fetus and that another defense of a moderate policy could be based on a finding that the ethical issue can not be decided and that no view about abortion ethics is more reasonable than any other. The essay concludes that the ethical debate is ultimately unavoidable.
Multipass diode-pumped solid-state optical amplifier
NASA Technical Reports Server (NTRS)
Plaessmann, Henry; Re, Sean A.; Alonis, Joseph J.; Vecht, David L.; Grossman, William M.
A new diode-pumped solid-state multipass amplifier produced 38-dB small-signal gain at 1.047 micron in Nd:YLF with 1.6-W pump power and 37 percent extraction efficiency near saturation. The amplifier had a 1:1 confocally reimaging multipass design that generated both high gain and high efficiency. The same amplifier design with 13 W of pump power was tested with Nd:YAG at 1.064 micron, which gave 38-dB small-signal gain and 3.2 W of output power, and with Nd:YVO4, also at 1.064 micron, which gave greater than 50-dB small-signal gain and 4.3 W of output power.
State estimation Kalman filter using optical processings Noise statistics known
NASA Technical Reports Server (NTRS)
Jackson, J.; Casasent, D.
Reference is made to a study by Casasent et al. (1983), which gave a description of a frequency-multiplexed acoustooptic processor and showed how it was capable of performing all the individual operations required in Kalman filtering. The data flow and organization of all required operations however, were not detailed in that study. Consideration is given here to a simpler Kalman filter state estimation problem. Equally spaced time-sampled intervals (k times T sub s, with k the iterative time index) are assumed. It is further assumed that the system noise vector w and the measurement noise vector v are uncorrelated and Gaussian distributed and that the noise statistics (Q and R) and the system model (Phi, Gamma, H) are known. The error covariance matrix P and the extrapolated error covariance matrix M can thus be precomputed and the Kalman gain matrix K sub k can be precomputed and stored for each input time sample.
Quantum state engineering of light with continuous-wave optical parametric oscillators.
Morin, Olivier; Liu, Jianli; Huang, Kun; Barbosa, Felippe; Fabre, Claude; Laurat, Julien
Engineering non-classical states of the electromagnetic field is a central quest for quantum optics(1,2). Beyond their fundamental significance, such states are indeed the resources for implementing various protocols, ranging from enhanced metrology to quantum communication and computing. A variety of devices can be used to generate non-classical states, such as single emitters, light-matter interfaces or non-linear systems(3). We focus here on the use of a continuous-wave optical parametric oscillator(3,4). This system is based on a non-linear χ(2) crystal inserted inside an optical cavity and it is now well-known as a very efficient source of non-classical light, such as single-mode or two-mode squeezed vacuum depending on the crystal phase matching. Squeezed vacuum is a Gaussian state as its quadrature distributions follow a Gaussian statistics. However, it has been shown that number of protocols require non-Gaussian states(5). Generating directly such states is a difficult task and would require strong χ(3) non-linearities. Another procedure, probabilistic but heralded, consists in using a measurement-induced non-linearity via a conditional preparation technique operated on Gaussian states. Here, we detail this generation protocol for two non-Gaussian states, the single-photon state and a superposition of coherent states, using two differently phase-matched parametric oscillators as primary resources. This technique enables achievement of a high fidelity with the targeted state and generation of the state in a well-controlled spatiotemporal mode.
Power of food moderates food craving, perceived control, and brain networks following a short-term post-absorptive state in older adults.
Rejeski, W Jack; Burdette, Jonathan; Burns, Marley; Morgan, Ashley R; Hayasaka, Satoru; Norris, James; Williamson, Donald A; Laurienti, Paul J
The Power of Food Scale (PFS) is a new measure that assesses the drive to consume highly palatable food in an obesogenic food environment. The data reported in this investigation evaluate whether the PFS moderates state cravings, control beliefs, and brain networks of older, obese adults following either a short-term post-absorptive state, in which participants were only allowed to consume water, or a short-term energy surfeit treatment condition, in which they consumed BOOST®. We found that the short-term post-absorptive condition, in which participants consumed water only, was associated with increases in state cravings for desired food, a reduction in participants' confidence related to the control of eating behavior, and shifts in brain networks that parallel what is observed with other addictive behaviors. Furthermore, individuals who scored high on the PFS were at an increased risk for experiencing these effects. Future research is needed to examine the eating behavior of persons who score high on the PFS and to develop interventions that directly target food cravings.
Power of Food ModeratesFood Craving, Perceived Control, and Brain Networks Following a Short-Term Post-Absorptive State in Older Adults
Rejeski, W. Jack; Burdette, Jonathan; Burns, Marley; Morgan, Ashley R.; Hayasaka, Satoru; Norris, James; Williamson, Donald; Laurienti, Paul J.
The Power of Food Scale (PFS) is a new measure that assesses the drive to consume highly palatable food in an obesogenic food environment. The data reported in this investigation evaluate whether the PFS moderates state cravings, control beliefs, and brain networks of older, obese adults following either a short-term post-absorptive state, in which participants were only allowed to consume water, or a short-term energy surfeit treatment condition, in which they consumed BOOST®. We found that the short-term post-absorptive condition,in which participants consumed water only, was associated withincreases in state cravings for desired food, a reduction in participants' confidence related to the control of eating behavior, and shifts in brain networks that parallel what is observed with other addictive behaviors. Furthermore, individuals who scored high on the PFSwere at an increased risk for experiencing these effects. Future research is needed to examine the eating behavior of persons who score high on the PFS and to develop interventions that directly target food cravings. PMID:22329987
Microscopic modeling of the effect of phonons on the optical properties of solid-state emitters
NASA Astrophysics Data System (ADS)
Norambuena, Ariel; Reyes, Sebastián A.; Mejía-Lopéz, José; Gali, Adam; Maze, Jerónimo R.
Understanding the effect of vibrations in optically active nanosystems is crucial for successfully implementing applications in molecular-based electro-optical devices, quantum information communications, single photon sources, and fluorescent markers for biological measurements. Here, we present a first-principles microscopic description of the role of phonons on the isotopic shift presented in the optical emission spectrum associated to the negatively charged silicon-vacancy color center in diamond. We use the spin-boson model and estimate the electron-phonon interactions using a symmetrized molecular description of the electronic states and a force-constant model to describe molecular vibrations. Group theoretical arguments and dynamical symmetry breaking are presented in order to explain the optical properties of the zero-phonon line and the isotopic shift of the phonon sideband.
Robust Light State by Quantum Phase Transition in Non-Hermitian Optical Materials
Zhao, Han; Longhi, Stefano; Feng, Liang
Robust light transport is the heart of optical information processing, leading to the search for robust light states by topological engineering of material properties. Here, it is shown that quantum phase transition, rather than topology, can be strategically exploited to design a novel robust light state. We consider an interface between parity-time (PT) symmetric media with different quantum phases and use complex Berry phase to reveal the associated quantum phase transition and topological nature. While the system possesses the same topological order within different quantum phases, phase transition from PT symmetry to PT breaking across the interface in the synthetic non-Hermitian metamaterial system facilitates novel interface states, which are robust against a variety of gain/loss perturbations and topological impurities and disorder. The discovery of the robust light state by quantum phase transition may promise fault-tolerant light transport in optical communications and computing. PMID:26592765
Fractional quantum Hall states of dipolar fermions in a strained optical lattice
NASA Astrophysics Data System (ADS)
Fujita, Hiroyuki; Nakagawa, Yuya O.; Ashida, Yuto; Furukawa, Shunsuke
We study strongly correlated ground states of dipolar fermions in a honeycomb optical lattice with spatial variations in hopping amplitudes. Similar to strained graphene, such nonuniform hopping amplitudes produce valley-dependent pseudomagnetic fields for fermions near the two Dirac points, resulting in the formation of Landau levels. The dipole moments aligned perpendicular to the honeycomb plane yield a long-range repulsive interaction. By exact diagonalization in the zeroth-Landau-level basis, we show that this repulsive interaction stabilizes a variety of valley-polarized fractional quantum Hall states such as Laughlin and composite-fermion states. The present system thus offers an intriguing platform for emulating fractional quantum Hall physics in a static optical lattice. We calculate the energy gaps above these incompressible states and discuss the temperature scales required for their experimental realization.
Chromophore Deprotonation State Alters the Optical Properties of Blue Chromoprotein
Chiang, Cheng-Yi; Lee, Cheng-Chung; Lo, Shin-Yi; Wang, Andrew H.-J.; Tsai, Huai-Jen
Chromoproteins (CPs) have unique colors and can be used in biological applications. In this work, a novel blue CP with a maximum absorption peak (λmax) at 608 nm was identified from the carpet anemone Stichodactyla gigantea (sgBP). In vivo expression of sgBP in zebrafish would change the appearance of the fishes to have a blue color, indicating the potential biomarker function. To enhance the color properties, the crystal structure of sgBP at 2.25 Å resolution was determined to allow structure-based protein engineering. Among the mutations conducted in the Gln-Tyr-Gly chromophore and chromophore environment, a S157C mutation shifted the λmax to 604 nm with an extinction coefficient (ε) of 58,029 M-1·cm-1 and darkened the blue color expression. The S157C mutation in the sgBP chromophore environment could affect the color expression by altering the deprotonation state of the phenolic group in the chromophore. Our results provide a structural basis for the blue color enhancement of the biomarker development. PMID:26218063
Enhanced optical cycling and slowing of YO through rotational state microwave mixing
NASA Astrophysics Data System (ADS)
Yan, Bo; Hummon, Matthew; Yeo, Mark; Collopy, Alejandra; Hemmerling, Boerge; Chae, Eunmi; Anderegg, Loic; Ravi, Aakash; Doyle, John; Ye, Jun
In order to address rotational dark states in the molecule yttrium (II) monoxide (YO) and to enhance optical cycling, we demonstrate the remixing of ground electronic state rotational levels using microwave radiation. This mixing technique, in conjunction with a broadband modulated and frequency chirped laser, is used to decelerate a beam of YO from a cryogenic buffer gas cell. The result is a population of molecules with velocities less than 10 m/s, which are sufficiently slow to be loaded into a magneto-optical trap. With two vibrational repump lasers, the cycling transition is closed to the 10-6 level. Additionally, we present progress towards a three dimensional implementation of a magneto-optical trap for YO. This work was supported in part by the Gordon and Betty Moore Foundation through Grant GBMF3852. We also acknowledge support from ARO, AFOSR (MURI), NIST, and NSF.
Generation of Symmetric Dicke States of Remote Qubits with Linear Optics
Thiel, C.; Zanthier, J. von; Bastin, T.; Solano, E.; Agarwal, G. S.
We propose a method for generating all symmetric Dicke states, either in the long-lived internal levels of N massive particles or in the polarization degrees of freedom of photonic qubits, using linear optical tools only. By means of a suitable multiphoton detection technique, erasing Welcher-Weg information, our proposed scheme allows the generation and measurement of an important class of entangled multiqubit states.
Generation and purification of maximally entangled atomic states in optical cavities
Lougovski, P.; Walther, H.; Solano, E.
We present a probabilistic scheme for generating and purifying maximally entangled states of two atoms inside an optical cavity via no-photon detection at the cavity output, where ideal detectors are not required. The intermediate mixed states can be continuously purified so as to violate Bell inequalities in a parametrized manner. The scheme relies on an additional strong-driving field that realizes, atypically, simultaneous Jaynes-Cummings and anti-Jaynes-Cummings interactions.
Optically induced effective mass renormalization: the case of graphite image potential states.
Montagnese, M; Pagliara, S; Galimberti, G; Dal Conte, S; Ferrini, G; van Loosdrecht, P H M; Parmigiani, F
Many-body interactions with the underlying bulk electrons determine the properties of confined electronic states at the surface of a metal. Using momentum resolved nonlinear photoelectron spectroscopy we show that one can tailor these many-body interactions in graphite, leading to a strong renormalization of the dispersion and linewidth of the image potential state. These observations are interpreted in terms of a basic self-energy model, and may be considered as exemplary for optically induced many-body interactions.
All-Optical Formation of Coherent Dark States of Silicon-Vacancy Spins in Diamond
NASA Astrophysics Data System (ADS)
Pingault, Benjamin; Becker, Jonas N.; Schulte, Carsten H. H.; Arend, Carsten; Hepp, Christian; Godde, Tillmann; Tartakovskii, Alexander I.; Markham, Matthew; Becher, Christoph; Atatüre, Mete
Spin impurities in diamond can be versatile tools for a wide range of solid-state-based quantum technologies, but finding spin impurities that offer sufficient quality in both photonic and spin properties remains a challenge for this pursuit. The silicon-vacancy center has recently attracted much interest because of its spin-accessible optical transitions and the quality of its optical spectrum. Complementing these properties, spin coherence is essential for the suitability of this center as a spin-photon quantum interface. Here, we report all-optical generation of coherent superpositions of spin states in the ground state of a negatively charged silicon-vacancy center using coherent population trapping. Our measurements reveal a characteristic spin coherence time, T2* , exceeding 45 nanoseconds at 4 K. We further investigate the role of phonon-mediated coupling between orbital states as a source of irreversible decoherence. Our results indicate the feasibility of all-optical coherent control of silicon-vacancy spins using ultrafast laser pulses.
Multiplexing free-space optical signals using superimposed collinear orbital angular momentum states
NASA Astrophysics Data System (ADS)
Lin, J.; Yuan, X.-C.; Tao, S. H.; Burge, R. E.
As a proof of concept, we experimentally demonstrate multiplexing of free-space optical signals in multiple channels labeled with different states of orbital angular momentum. The multiplexing process is carried out by a dynamic liquid-crystal spatial light modulator, while the phase function is calculated by an iterative algorithm. A binary amplitude computer-generated hologram serves as a demultiplexer.
Solid-state reversible quadratic nonlinear optical molecular switch with an exceptionally large contrast.
Sun, Zhihua; Luo, Junhua; Zhang, Shuquan; Ji, Chengmin; Zhou, Lei; Li, Shenhui; Deng, Feng; Hong, Maochun
Exceptional nonlinear optical (NLO) switching behavior, including an extremely large contrast (on/off) of ∼35 and high NLO coefficients, is displayed by a solid-state reversible quadratic NLO switch. The favorable results, induced by very fast molecular motion and anionic ordering, provides impetus for the design of a novel second-harmonic-generation switch involving molecular motion.
Optical interferometry diagnostics in laser-driven equation of state experiments
Cauble, R C; Celliers, P M; Collins, G W; Da Silva, L B; Gold, D M; Kalantar, D H; Remington, B A; Weber, S V
We have developed and tested several optical interferometric diagnostics to measure preheat and shock velocity in high-pressure equation of state experiments on the Nova laser. Theory and practical application of interferometric measurement techniques with illustrative experimental results are presented.
Two-photon-state generation via four-wave mixing in optical fibers
Chen Jun; Li Xiaoying; Kumar, Prem
A quantum theory of two-photon-state generation via four-wave mixing in optical fibers is studied, with emphasis on the case where the pump is a classical, narrow (picosecond-duration) pulse. One of the experiments performed in our lab is discussed and analyzed. Numerical predictions from the theory are shown to be in good agreement with the experimental results.
Local density of optical states of an asymmetric waveguide grating at photonic band gap resonant wavelength
NASA Astrophysics Data System (ADS)
Alatas, Husin; Sumaryada, Tony I.; Ahmad, Faozan
We have investigated the characteristics of local density of optical states (LDOS) at photonic band gap resonant wavelength of an asymmetric waveguide grating based on Green's function formulation. It is found that the LDOS of the considered structure exhibits different characteristics in its localization between the upper and lower resonant wavelengths of the corresponding photonic band gap edges.
Concentrating partially entangled W-class states on nonlocal atoms using low- Q optical cavity and linear optical elements
NASA Astrophysics Data System (ADS)
Cao, Cong; Chen, Xi; Duan, YuWen; Fan, Ling; Zhang, Ru; Wang, TieJun; Wang, Chuan
Entanglement plays an important role in quantum information science, especially in quantum communications. Here we present an efficient entanglement concentration protocol (ECP) for nonlocal atom systems in the partially entangled W-class states, using the single-photon input-output process regarding low- Q cavity and linear optical elements. Compared with previously published ECPs for the concentration of non-maximally entangled atomic states, our protocol is much simpler and more efficient as it employs the Faraday rotation in cavity quantum electrodynamics (QED) and the parameter-splitting method. The Faraday rotation requires the cavity with low- Q factor and weak coupling to the atom, which makes the requirement for entanglement concentration much less stringent than the previous methods, and achievable with current cavity QED techniques. The parameter-splitting method resorts to linear-optical elements only. This ECP has high efficiency and fidelity in realistic experiments, and some imperfections during the experiment can be avoided efficiently with currently available techniques.
A State-of-the-Science Overview of Randomized Controlled Trials Evaluating Acute Management of Moderate-to-Severe Traumatic Brain Injury.
Bragge, Peter; Synnot, Anneliese; Maas, Andrew I; Menon, David K; Cooper, D James; Rosenfeld, Jeffrey V; Gruen, Russell L
Moderate-to-severe traumatic brain injury (TBI) remains a major global challenge, with rising incidence, unchanging mortality and lifelong impairments. State-of-the-science reviews are important for research planning and clinical decision support. This review aimed to identify randomized controlled trials (RCTs) evaluating interventions for acute management of moderate/severe TBI, synthesize key RCT characteristics and findings, and determine their implications on clinical practice and future research. RCTs were identified through comprehensive database and other searches. Key characteristics, outcomes, risk of bias, and analysis approach were extracted. Data were narratively synthesized, with a focus on robust (multi-center, low risk of bias, n > 100) RCTs, and three-dimensional graphical figures also were used to explore relationships between RCT characteristics and findings. A total of 207 RCTs were identified. The 191 completed RCTs enrolled 35,340 participants (median, 66). Most (72%) were single center and enrolled less than 100 participants (69%). There were 26 robust RCTs across 18 different interventions. For 74% of 392 comparisons across all included RCTs, there was no significant difference between groups. Positive findings were broadly distributed with respect to RCT characteristics. Less than one-third of RCTs demonstrated low risk of bias for random sequence generation or allocation concealment, less than one-quarter used covariate adjustment, and only 7% employed an ordinal analysis approach. Considerable investment of resources in producing 191 completed RCTs for acute TBI management has resulted in very little translatable evidence. This may result from broad distribution of research effort, small samples, preponderance of single-center RCTs, and methodological shortcomings. More sophisticated RCT design, large multi-center RCTs in priority areas, increased focus on pre-clinical research, and alternatives to RCTs, such as comparative
Sildenafil does not improve steady state cardiovascular hemodynamics, peak power, or 15-km time trial cycling performance at simulated moderate or high altitudes in men and women.
Kressler, Jochen; Stoutenberg, Mark; Roos, Bernard A; Friedlander, Anne L; Perry, Arlette C; Signorile, Joseph F; Jacobs, Kevin A
Sildenafil improves oxygen delivery and maximal exercise capacity at very high altitudes (≥ 4,350 m), but it is unknown whether sildenafil improves these variables and longer-duration exercise performance at moderate and high altitudes where competitions are more common. The purpose of this study was to determine the effects of sildenafil on cardiovascular hemodynamics, arterial oxygen saturation (SaO(2)), peak exercise capacity (W (peak)), and 15-km time trial performance in endurance-trained subjects at simulated moderate (MA; ~2,100 m, 16.2% F(I)O(2)) and high (HA; ~3,900 m, 12.8% F(I)O(2)) altitudes. Eleven men and ten women completed two HA W (peak) trials after ingesting placebo or 50 mg sildenafil. Subjects then completed four exercise trials (30 min at 55% of altitude-specific W (peak) + 15-km time trial) at MA and HA after ingesting placebo or 50 mg sildenafil. All trials were performed in randomized, counterbalanced, and double-blind fashion. Sildenafil had little influence on cardiovascular hemodynamics at MA or HA, but did result in higher SaO(2) values (+3%, p < 0.05) compared to placebo during steady state and time trial exercise at HA. W (peak) at HA was 19% lower than SL (p < 0.001) and was not significantly affected by sildenafil. Similarly, the significantly slower time trial performance at MA (28.1 ± 0.5 min, p = 0.016) and HA (30.3 ± 0.6 min, p < 0.001) compared to SL (27.5 ± 0.6 min) was unaffected by sildenafil. We conclude that sildenafil is unlikely to exert beneficial effects at altitudes <4,000 m for a majority of the population.
Cs 728 nm excited state Faraday anomalous dispersion optical filter with indirect pump
NASA Astrophysics Data System (ADS)
Tao, Zhiming; Zhang, Xiaogang; Chen, Mo; Liu, Zhongzheng; Zhu, Chuanwen; Liu, Zhiwen; Chen, Jingbiao
We demonstrate a Cs excited state Faraday anomalous dispersion optical filter (ESFADOF) operating at 728 nm using a novel pump method, by which the pump beam and the probe beam in the ESFADOF realized here have no a common energy level. Using this method, the ESFADOF achieves a transmission of 2.39% with a bandwidth of 22.52 MHz, which can be applied to both laser frequency stabilization and future four-level active optical clocks. Under the 455 nm laser pump, in addition to 52D5/2, other states such as 72S1/2, 72P3/2, 62P3/2, 62P1/2 and 52D3/2 have also been populated effectively. Meanwhile, multiple wavelength filters exploiting atomic transitions to these states can be realized.
Semiclassical Wigner distribution for a two-mode entangled state generated by an optical parametric oscillator
Dechoum, K.; Hahn, M. D.; Khoury, A. Z.
We derive the steady-state solution of the Fokker-Planck equation that describes the dynamics of the nondegenerate optical parametric oscillator in the truncated Wigner representation of the density operator. We assume that the pump mode is strongly damped, which permits its adiabatic elimination. When the elimination is correctly executed, the resulting stochastic equations contain multiplicative noise terms and do not admit a potential solution. However, we develop a heuristic scheme leading to a satisfactory steady-state solution. This provides a clear view of the intracavity two-mode entangled state valid in all operating regimes of the optical parametric oscillator. A non-Gaussian distribution is obtained for the above threshold solution.
Optical study of nonuniform quantum-Hall ferromagnetic states in bilayer and trilayer graphene
NASA Astrophysics Data System (ADS)
Barrette, Manuel; Côté, René
The chiral two-dimensional electron gas in the N = 0 Landau level of a Bernal-stacked bilayer graphene is host to a variety of broken-symmetry ground states that can be described as layer, spin, or orbital quantum Hall ferromagnets (QHFs). At filling factors ν = 1 , 3 , an externally applied electric field between the two layers can induce a transition from uniform to nonuniform orbital QHF states with an helical or skyrmionic texture of electric dipoles. A similar skyrmionic texture can also arise in the N = 0 Landau level of an ABC-stacked trilayer graphene. In this talk, we discuss the optical properties of these textured ground states. We compute their electromagnetic absorption as well as the Kerr and Faraday rotations induced by their collective excitations and show that each textured phase has a distinct optical signature.
Unconventional optical Tamm defect states in metal-terminated opal photonic crystals
NASA Astrophysics Data System (ADS)
Korovin, Alexander V.; Romanov, Sergei G.
Optical Tamm surface states are formed in 3-dimensional photonic crystals coated by thin metal films. These states appear in registry with diffraction resonances and localize the electromagnetic energy in resonators formed by diffraction mirrors of lattice planes and metal semishells. Tamm defect states provide the bypass for light in the spectral range of photonic stop-bands and thus reduce the efficiency of the Bragg diffraction resonances. In spite of hidden nature of this effect, its magnitude is comparable to the extraordinary transmission associated with tunneling of surface plasmon polaritons, which are simultaneously excited at surfaces of corrugated metal film coating.
Unconventional optical Tamm states in metal-terminated three-dimensional photonic crystals
NASA Astrophysics Data System (ADS)
Korovin, Alexander V.; Romanov, Sergei G.
Unconventional optical Tamm surface states have been demonstrated in transmission and reflectance spectra of three-dimensional opal photonic crystals coated by thin metal films. These states appear in registry with diffraction resonances and localize the electromagnetic energy in asymmetric resonators formed by stacks of lattice planes and metal semishells. Tamm defect states provide the bypass for light at the edges of the Bragg diffraction resonances and thus reduce the diffraction efficiency. Despite the hidden nature of this effect, its magnitude is comparable to the extraordinary transmission associated with the surface-plasmon polaritons that are simultaneously excited at the surfaces of the corrugated metal films.
Spectral engineering by flexible tunings of optical Tamm states and Fabry-Perot cavity resonance.
Zhang, Xu-Lin; Song, Jun-Feng; Feng, Jing; Sun, Hong-Bo
We present a design for spectral engineering in a metal dual distributed Bragg reflector (DBR)-based structure. Optical Tamm states and Fabry-Perot cavity mode, dual windows for light-matter interaction enhancement, can be excited simultaneously and tuned flexibly, including their respective bandwidth and resonant wavelength, due to the variable reflection phase from the outer DBR's internal surface. The design can find applications in solar cells for light trappings. Via calculations of overall absorptivity, the proposed simpler dual-states-based scheme is demonstrated to be almost as effective as the coherent-light-trapping scheme, owing to the dual-states-induced broader-band absorption enhancement.
Quantum phases of the extended Bose-Hubbard hamiltonian: possibility of a supersolid state of cold atoms in optical lattices.
Scarola, V W; Das Sarma, S
Cold atom optical lattices typically simulate zero-range Hubbard models. We discuss the theoretical possibility of using excited states of optical lattices to generate extended range Hubbard models. We find that bosons confined to higher bands of optical lattices allow for a rich phase diagram, including the supersolid phase. Using Gutzwiller, mean-field theory we establish the parameter regime necessary to maintain metastable states generated by an extended Bose-Hubbard model.
Low-Entropy States of Neutral Atoms in Polarization-Synthesized Optical Lattices.
Robens, Carsten; Zopes, Jonathan; Alt, Wolfgang; Brakhane, Stefan; Meschede, Dieter; Alberti, Andrea
We create low-entropy states of neutral atoms by utilizing a conceptually new optical-lattice technique that relies on a high-precision, high-bandwidth synthesis of light polarization. Polarization-synthesized optical lattices provide two fully controllable optical lattice potentials, each of them confining only atoms in either one of the two long-lived hyperfine states. By employing one lattice as the storage register and the other one as the shift register, we provide a proof of concept using four atoms that selected regions of the periodic potential can be filled with one particle per site. We expect that our results can be scaled up to thousands of atoms by employing an atom-sorting algorithm with logarithmic complexity, which is enabled by polarization-synthesized optical lattices. Vibrational entropy is subsequently removed by sideband cooling methods. Our results pave the way for a bottom-up approach to creating ultralow-entropy states of a many-body system.
Variable pulse repetition frequency output from an optically injected solid state laser.
Kane, D M; Toomey, J P
An optically injected solid state laser (OISSL) system is known to generate complex nonlinear dynamics within the parameter space of varying the injection strength of the master laser and the frequency detuning between the master and slave lasers. Here we show that within these complex nonlinear dynamics, a system which can be operated as a source of laser pulses with a pulse repetition frequency (prf) that can be continuously varied by a single control, is embedded. Generation of pulse repetition frequencies ranging from 200 kHz up to 4 MHz is shown to be achievable for an optically injected Nd:YVO4 solid state laser system from analysis of prior experimental and simulation results. Generalizing this to other optically injected solid state laser systems, the upper bound on the repetition frequency is of order the relaxation oscillation frequency for the lasers. The system is discussed in the context of prf versatile laser systems more generally. Proposals are made for the next generation of OISSLs that will increase understanding of the variable pulse repetition frequency operation, and determine its practical limitations. Such variable prf laser systems; both low powered, and, higher powered systems achieved using one or more optical power amplifier stages; have many potential applications from interrogating resonance behaviors in microscale structures, through sensing and diagnostics, to laser processing.
Low-Entropy States of Neutral Atoms in Polarization-Synthesized Optical Lattices
NASA Astrophysics Data System (ADS)
Robens, Carsten; Zopes, Jonathan; Alt, Wolfgang; Brakhane, Stefan; Meschede, Dieter; Alberti, Andrea
We create low-entropy states of neutral atoms by utilizing a conceptually new optical-lattice technique that relies on a high-precision, high-bandwidth synthesis of light polarization. Polarization-synthesized optical lattices provide two fully controllable optical lattice potentials, each of them confining only atoms in either one of the two long-lived hyperfine states. By employing one lattice as the storage register and the other one as the shift register, we provide a proof of concept using four atoms that selected regions of the periodic potential can be filled with one particle per site. We expect that our results can be scaled up to thousands of atoms by employing an atom-sorting algorithm with logarithmic complexity, which is enabled by polarization-synthesized optical lattices. Vibrational entropy is subsequently removed by sideband cooling methods. Our results pave the way for a bottom-up approach to creating ultralow-entropy states of a many-body system.
Aerosol optical properties and mixing state of black carbon in the Pearl River Delta, China
NASA Astrophysics Data System (ADS)
Tan, Haobo; Liu, Li; Fan, Shaojia; Li, Fei; Yin, Yan; Cai, Mingfu; Chan, P. W.
Aerosols contribute the largest uncertainty to the total radiative forcing estimate, and black carbon (BC) that absorbs solar radiation plays an important role in the Earth's energy budget. This study analysed the aerosol optical properties from 22 February to 18 March 2014 at the China Meteorological Administration Atmospheric Watch Network (CAWNET) station in the Pearl River Delta (PRD), China. The representative values of dry-state particle scattering coefficient (σsp), hemispheric backscattering coefficient (σhbsp), absorption coefficient (σabsp), extinction coefficient (σep), hemispheric backscattering fraction (HBF), single scattering albedo (SSA), as well as scattering Ångström exponent (α) were presented. A comparison between a polluted day and a clean day shows that the aerosol optical properties depend on particle number size distribution, weather conditions and evolution of the mixing layer. To investigate the mixing state of BC at the surface, an optical closure study of HBF between measurements and calculations based on a modified Mie model was employed for dry particles. The result shows that the mixing state of BC might be between the external mixture and the core-shell mixture. The average retrieved ratio of the externally mixed BC to the total BC mass concentration (rext-BC) was 0.58 ± 0.12, and the diurnal pattern of rext-BC can be found. Furthermore, considering that non-light-absorbing particles measured by a Volatility-Tandem Differential Mobility Analyser (V-TDMA) exist independently with core-shell and homogenously internally mixed BC particles, the calculated optical properties were just slightly different from those based on the assumption that BC exist in each particle. This would help understand the influence of the BC mixing state on aerosol optical properties and radiation budget in the PRD.
Continuous Variable Cluster State Generation over the Optical Spatial Mode Comb
Pooser, Raphael C.; Jing, Jietai
One way quantum computing uses single qubit projective measurements performed on a cluster state (a highly entangled state of multiple qubits) in order to enact quantum gates. The model is promising due to its potential scalability; the cluster state may be produced at the beginning of the computation and operated on over time. Continuous variables (CV) offer another potential benefit in the form of deterministic entanglement generation. This determinism can lead to robust cluster states and scalable quantum computation. Recent demonstrations of CV cluster states have made great strides on the path to scalability utilizing either time or frequency multiplexingmore » in optical parametric oscillators (OPO) both above and below threshold. The techniques relied on a combination of entangling operators and beam splitter transformations. Here we show that an analogous transformation exists for amplifiers with Gaussian inputs states operating on multiple spatial modes. By judicious selection of local oscillators (LOs), the spatial mode distribution is analogous to the optical frequency comb consisting of axial modes in an OPO cavity. We outline an experimental system that generates cluster states across the spatial frequency comb which can also scale the amount of quantum noise reduction to potentially larger than in other systems.« less
Nonlinear optical properties of tetrapyrazinoporphyrazinato indium chloride complexes due to excited-state absorption processes.
Dini, Danilo; Hanack, Michael; Meneghetti, Moreno
The multiphoton absorption properties of the axially substituted tetrapyrazinotetraazaporphyrinato complex Pyz(4)TAPInCl (1) are reported and interpreted. In particular, the nonlinear optical transmission of the complex and the excited states involved in the nonlinear absorption have been determined at the frequency of the second harmonic generation of a Nd:YAG laser in the nanosecond time regime. Pyz(4)TAPInCl has an excited-state absorption cross section larger than its ground state in the 460-540 nm spectral region, and it shows an optical limiting (OL) behavior at 532 nm, which derives from a sequential two-photon absorption with a larger absorption cross section of the excited triplet state with respect to the ground state. It results that the absorption cross section of 1 in the excited triplet state is 7.8 x 10(-18) cm(2) vs 0.9 x 10(-18) cm(2) of the ground state at the wavelength of OL analysis.
Continuous Variable Cluster State Generation over the Optical Spatial Mode Comb
Pooser, Raphael C.; Jing, Jietai
One way quantum computing uses single qubit projective measurements performed on a cluster state (a highly entangled state of multiple qubits) in order to enact quantum gates. The model is promising due to its potential scalability; the cluster state may be produced at the beginning of the computation and operated on over time. Continuous variables (CV) offer another potential benefit in the form of deterministic entanglement generation. This determinism can lead to robust cluster states and scalable quantum computation. Recent demonstrations of CV cluster states have made great strides on the path to scalability utilizing either time or frequency multiplexing in optical parametric oscillators (OPO) both above and below threshold. The techniques relied on a combination of entangling operators and beam splitter transformations. Here we show that an analogous transformation exists for amplifiers with Gaussian inputs states operating on multiple spatial modes. By judicious selection of local oscillators (LOs), the spatial mode distribution is analogous to the optical frequency comb consisting of axial modes in an OPO cavity. We outline an experimental system that generates cluster states across the spatial frequency comb which can also scale the amount of quantum noise reduction to potentially larger than in other systems.
State-projective scheme for generating pair coherent states in traveling-wave optical fields
Gerry, Christopher C.; Mimih, Jihane; Birrittella, Richard
The pair coherent states of a two-mode quantized electromagnetic field introduced by Agarwal [Phys. Rev. Lett. 57, 827 (1986)] have yet to be generated in the laboratory. The states can mathematically be obtained from a product of ordinary coherent states via projection onto a subspace wherein identical photon number states of each mode are paired. We propose a scheme by which this projection can be engineered. The scheme requires relatively weak cross-Kerr nonlinearities, the ability to perform a displacement operation on a beam mode, and photon detection ability able to distinguish between zero and any other number of photons. These requirements can be fulfilled with currently available technology or technology that is on the horizon.
Fano resonances in photonic crystal slabs near optical bound states in the continuum
NASA Astrophysics Data System (ADS)
Blanchard, Cédric; Hugonin, Jean-Paul; Sauvan, Christophe
Photonic crystal slabs are able to support optical bound states in the continuum. The latter are eigenmodes of the structure that are truly guided (no radiation leakage) despite the fact that they lie above the light cone within the continuum of radiation modes. Such peculiar states can be viewed as modes with an infinite quality factor Q . Therefore, the question of the behavior of Fano resonances, as optogeometrical parameters are tuned close to optical bound states in the continuum, is of importance for applications of photonic crystal slabs with ultrahigh Q factors. We study theoretically the reflection and transmission of a photonic crystal slab close to an optical bound state in the continuum with a phenomenological approach involving the poles and zeros of the scattering matrix. In particular, we derive a general relation valid for asymmetric structures that gives the position of a pole in the complex plane as a function of the positions of the zeros. We provide closed-form expressions for the reflection and transmission. The proposed phenomenological approach is validated through rigorous numerical calculations.
Optical diode action from axially asymmetric nonlinearity in an all-carbon solid-state device.
Anand, Benoy; Podila, Ramakrishna; Lingam, Kiran; Krishnan, S R; Siva Sankara Sai, S; Philip, Reji; Rao, Apparao M
Nanostructured carbons are posited to offer an alternative to silicon and lead to further miniaturization of photonic and electronic devices. Here, we report the experimental realization of the first all-carbon solid-state optical diode that is based on axially asymmetric nonlinear absorption in a thin saturable absorber (graphene) and a thin reverse saturable absorber (C60) arranged in tandem. This all-optical diode action is polarization independent and has no phase-matching constraints. The nonreciprocity factor of the device can be tuned by varying the number of graphene layers and the concentration or thickness of the C60 coating. This ultracompact graphene/C60 based optical diode is versatile with an inherently large bandwidth, chemical and thermal stability, and is poised for cost-effective large-scale integration with existing fabrication technologies.
The gamma-ray blazar quest: new optical spectra, state of art and future perspectives
NASA Astrophysics Data System (ADS)
Massaro, F.; Álvarez Crespo, N.; D'Abrusco, R.; Landoni, M.; Masetti, N.; Ricci, F.; Milisavljevic, D.; Paggi, A.; Chavushyan, V.; Jiménez-Bailón, E.; Patiño-Álvarez, V.; Strader, J.; Chomiuk, L.; La Franca, F.; Smith, Howard A.; Tosti, G.
We recently developed a procedure to recognize γ-ray blazar candidates within the positional uncertainty regions of the unidentified/unassociated γ-ray sources (UGSs). Such procedure was based on the discovery that Fermi blazars show peculiar infrared colors. However, to confirm the real nature of the selected candidates, optical spectroscopic data are necessary. Thus, we performed an extensive archival search for spectra available in the literature in parallel with an optical spectroscopic campaign aimed to reveal and confirm the nature of the selected γ-ray blazar candidates. Here, we first search for optical spectra of a selected sample of γ-ray blazar candidates that can be potential counterparts of UGSs using the Sloan Digital Sky Survey (SDSS DR12). This search enables us to update the archival search carried out to date. We also describe the state-of-art and the future perspectives of our campaign to discover previously unknown γ-ray blazars.
Resolving phase information of the optical local density of state with scattering near-field probes
NASA Astrophysics Data System (ADS)
Prasad, R.; Vincent, R.
We theoretically discuss the link between the phase measured using a scattering optical scanning near-field microscopy (s-SNOM) and the local density of optical states (LDOS). A remarkable result is that the LDOS information is directly included in the phase of the probe. Therefore by monitoring the spatial variation of the trans-scattering phase, we locally measure the phase modulation associated with the probe and the optical paths. We demonstrate numerically that a technique involving two-phase imaging of a sample with two different sized tips should allow to obtain the image the pLDOS. For this imaging method, numerical comparison with extinction probe measurement shows crucial qualitative and quantitative improvement.
Scheme for generating the singlet state of three atoms trapped in distant cavities coupled by optical fibers
Wang, Dong-Yang; Wen, Jing-Ji; Bai, Cheng-Hua; Hu, Shi; Cui, Wen-Xue; Wang, Hong-Fu; Zhu, Ai-Dong; Zhang, Shou
An effective scheme is proposed to generate the singlet state with three four-level atoms trapped in three distant cavities connected with each other by three optical fibers, respectively. After a series of appropriate atom–cavity interactions, which can be arbitrarily controlled via the selective pairing of Raman transitions and corresponding optical switches, a three-atom singlet state can be successfully generated. The influence of atomic spontaneous decay, photon leakage of cavities and optical fibers on the fidelity of the state is numerically simulated showing that the three-atom singlet state can be generated with high fidelity by choosing the experimental parameters appropriately.
Effect of an excited-state optical transition on the linewidth enhancement factor of quantum dot lasers
Zhukov, A. E. Savelyev, A. V.; Maximov, M. V.; Shernyakov, Yu. M.; Arakcheeva, E. M.; Zubov, F. I.; Krasivichev, A. A.; Kryzhanovskaya, N. V.
An analytical expression is derived for the linewidth enhancement factor of a quantum-dot laser, which makes it possible to describe its dependence on optical loss and photon density in an explicit form. The model accounts for refractive index variations at the ground-state optical transition due to gain/absorption variations upon the first excited-state transition in quantum dots. It is shown that a decrease in optical loss, an increase in saturated gain, and an increase in the energy separation between the excited-state and ground-state transitions results in a decrease in the {alpha} factor both at and above the lasing threshold.
High precision optical spectroscopy and quantum state selected photodissociation of ultracold 88Sr2 molecules in an optical lattice
NASA Astrophysics Data System (ADS)
McDonald, Mickey Patrick
Over the past several decades, rapid progress has been made toward the accurate characterization and control of atoms, made possible largely by the development of narrow-linewidth lasers and techniques for trapping and cooling at ultracold temperatures. Extending this progress to molecules will have exciting implications for chemistry, condensed matter physics, and precision tests of physics beyond the Standard Model. These possibilities are all consequences of the richness of molecular structure, which is governed by physics substantially different from that characterizing atomic structure. This same richness of structure, however, increases the complexity of any molecular experiment manyfold over its atomic counterpart, magnifying the difficulty of everything from trapping and cooling to the comparison of theory with experiment. This thesis describes work performed over the past six years to establish the state of the art in manipulation and quantum control of ultracold molecules. Our molecules are produced via photoassociation of ultracold strontium atoms followed by spontaneous decay to a stable ground state. We describe a thorough set of measurements characterizing the rovibrational structure of very weakly bound (and therefore very large) 88Sr2 molecules from several different perspectives, including determinations of binding energies; linear, quadratic, and higher order Zeeman shifts; transition strengths between bound states; and lifetimes of narrow subradiant states. The physical intuition gained in these experiments applies generally to weakly bound diatomic molecules, and suggests extensive applications in precision measurement and metrology. In addition, we present a detailed analysis of the thermally broadened spectroscopic lineshape of molecules in a non-magic optical lattice trap, showing how such lineshapes can be used to directly determine the temperature of atoms or molecules in situ, addressing a long-standing problem in ultracold physics
Self-assembly solid-state enhanced red emission of quinolinemalononitrile: optical waveguides and stimuli response.
Shi, Chuanxing; Guo, Zhiqian; Yan, Yongli; Zhu, Shiqin; Xie, Yongshu; Zhao, Yong Sheng; Zhu, Weihong; Tian, He
The fluorescence of luminescent emitters is often quenched in the solid state, because of the typical aggregation-caused quenching (ACQ) effect, which is a thorny obstacle to high-performance organic optoelectronic materials. The exploration of solid-state enhanced long wavelength, red-emitting chromophores, especially possessing one-dimensional (1D) assembly features, is of great importance. Interestingly, an excellent solid-state enhanced red emission system (denoted as ED) based on quinolinemalononitrile has been developed via the delicate modification of the conventional ACQ dicyanomethylene-4H-pyran (DCM) derivative (denoted as BD) through crystal engineering. ED exhibits extraordinary self-assembly property in a variety of solvents, even realizing the "waving ribbons" with a length of 6 mm and a diameter of 10 μm. Crystal analysis shows that the CH···π and CH···N supramolecular interactions of ED contribute to the twisted self-assembly solid-state enhanced emission phenomenon. However, for BD, strong face-to-face stacking leads to fluorescence quenching in the solid state. Because of such easy assembly and strong solid-state emission properties, application for optical waveguides of ED is realized with a low optical loss. Stimuli-responsive behavior is also elaborated with color change between orange and red by grinding/fuming or pressing/heating.
Molecular states in double quantum wells: nanochemistry for metatmaterials with new optical properties
NASA Astrophysics Data System (ADS)
Gutierrez, Rafael M.; Castañeda, Arcesio
Quantum mechanics explains the existence and properties of the chemical bond responsible for the formation of molecules from isolated atoms. In this work we study quantum states of Double Quantum Wells, DQW, formed from isolated Single Quantum Wells, SQWs, that can be considered metamaterials. Using the quantum chemistry definition of the covalent bond, we discuss molecular states in DQW as a kind of nanochemistry of metamaterials with new properties, in particular new optical properties. An important particularity of such nanochemistry, is the possible experimental control of the geometrical parameters and effective masses characterizing the semiconductor heterostructures represented by the corresponding DQW. This implies a great potential for new applications of the controlled optical properties of the metamaterials. The use of ab initio methods of intensive numerical calculations permits to obtain macroscopic optical properties of the metamaterials from the fundamental components: the spatial distribution of the atoms and molecules constituting the semiconductor layers. The metamaterial new optical properties emerge from the coexistence of many body processes at atomic and molecular level and complex quantum phenomena such as covalent-like bonds at nanometric dimensions.
Charge-transfer states and optical transitions at the pentacene-TiO2 interface
NASA Astrophysics Data System (ADS)
Ljungberg, M. P.; Vänskä, O.; Koval, P.; Koch, S. W.; Kira, M.; Sánchez-Portal, D.
Pentacene molecules have recently been observed to form a well-ordered monolayer on the (110) surface of rutile TiO2, with the molecules adsorbed lying flat, head to tail. With the geometry favorable for direct optical excitation and given its ordered character, this interface seems to provide an intriguing model to study charge-transfer excitations where the optically excited electrons and holes reside on different sides of the organic–inorganic interface. In this work, we theoretically investigate the structural and electronic properties of this system by means of ab initio calculations and compute its excitonic absorption spectrum. Molecular states appear in the band gap of the clean TiO2 surface, which enables charge-transfer excitations directly from the molecular HOMO to the TiO2 conduction band. The calculated optical spectrum shows a strong polarization dependence and displays excitonic resonances corresponding to the charge-transfer states, which could stimulate new experimental work on the optical response of this interface.
Silicon-nanowire-based optical hybrid with insensitive operation for TE/TM states of polarization
NASA Astrophysics Data System (ADS)
Wang, Jin; Zhai, Yumeng; Mao, Jinbin; Lu, Yunqing; Xu, Ji; Dai, Daoxin
An optical 90° hybrid consisting of a polarization splitter-rotator (PSR) and a multimode interferometer (MMI) is proposed to realize insensitive optical frequency mixing for TE/TM states of polarization. The PSR is based on the mode hybridization and mode coupling between waveguides; input light at a fundamental transverse electric (TE) mode and a transverse magnetic (TM) mode are output at separate ports, but both output signals are in the fundamental TE mode. These two output fields are then guided to the MMI, where the optical frequency mixing with the light of a local oscillator takes place. This mixing is then independent of the state of polarization of the hybrid input light. We designed such an optical hybrid based on silicon-nanowire waveguides. At a wavelength of 1540 nm, simulation results for the hybrid show a transmission efficiency of 98.6% or 95.8% for TE- or TM-polarized input light, respectively, while the transmission efficiencies for both polarizations are above 90% in a 30 nm wavelength range, namely [1525 nm, 1555 nm]. Further, in the wavelength range [1510 nm, 1565 nm], the transmission imbalance between the output fields is below 0.85 dB for TE- or TM-polarized input light, respectively, while the phase errors in both cases are less than 4°.
Through-wafer optical probe characterization for microelectromechanical systems positional state monitoring and feedback control
NASA Astrophysics Data System (ADS)
Dawson, Jeremy M.; Chen, Jingdong; Brown, Kolin S.; Famouri, Parviz F.; Hornak, Lawrence A.
Implementation of closed-loop microelectromechanical system (MEMS) control enables mechanical microsystems to adapt to the demands of the environment that they are actuating, opening a broad range of new opportunities for future MEMS applications. Integrated optical microsystems have the potential to enable continuous in situ optical interrogation of MEMS microstructure position fully decoupled from the means of mechanical actuation that is necessary for realization of feedback control. We present the results of initial research evaluating through-wafer optical microprobes for surface micromachined MEMS integrated optical position monitoring. Results from the through-wafer free-space optical probe of a lateral comb resonator fabricated using the multiuser MEMS process service (MUMPS) indicate significant positional information content with an achievable return probe signal dynamic range of up to 80% arising from film transmission contrast. Static and dynamic deflection analysis and experimental results indicate a through-wafer probe positional signal sensitivity of 40 mV/micrometers for the present setup or 10% signal change per micrometer. A simulation of the application of nonlinear sliding control is presented illustrating position control of the lateral comb resonator structure given the availability of positional state information.
The Initial State of Optically Polarized 8Li+ from the β-NMR in Bismuth
NASA Astrophysics Data System (ADS)
MacFarlane, W. A.; Levy, C. D. P.; Pearson, M. R.; Buck, T.; Chow, K. H.; Hariwal, A. N.; Kiefl, R. F.; McGee, F. H.; Morris, G. D.; Wang, D.
Unlike the positive muon, β-NMR probe nuclei must be actively polarized. At the TRIUMF ISAC facility this is accomplished by in-flight collinear optical pumping with resonant circularly polarized laser light. This reliably produces a high degree of polarization, but the detailed state populations in the beam emerging from the optical polarizer are not well known. These populations are significant as they represent the initial state of the ensemble of probe spins implanted in a β-NMR experiment. Here we use the well-resolved quadrupolar split spectrum of 8Li+ in a high purity single crystal of bismuth to extract the sublevel populations under typical polarizer operating conditions, accounting for the spin relaxation in this semimetal.
Ultrasensitive optical absorption in graphene based on bound states in the continuum
Zhang, Mingda; Zhang, Xiangdong
We have designed a sphere-graphene-slab structure so that the electromagnetic wave can be well confined in the graphene due to the formation of a bound state in a continuum (BIC) of radiation modes. Based on such a bound state, we have realized strong optical absorption in the monolayer graphene. Such a strong optical absorption exhibits many advantages. It is ultrasensitive to the wavelength because the Q factor of the absorption peak can be more than 2000. By taking suitable BICs, the selective absorption for S and P waves has not only been realized, but also all-angle absorption for the S and P waves at the same time has been demonstrated. We have also found that ultrasensitive strong absorptions can appear at any wavelength from mid-infrared to far-infrared band. These phenomena are very beneficial to biosensing, perfect filters and waveguides. PMID:25652437
Portable, solid state, fiber optic coupled Doppler interferometer system for detonation and shock diagnostics
Fleming, K.J.
VISAR (Velocity Interferometer System for Any Reflector) is a specialized Doppler interferometer system that is gaining world-wide acceptance as the standard for shock phenomena analysis. The VISAR`s large power and cooling requirements, and the sensitive and complex nature of the interferometer cavity has restricted the traditional system to the laboratory. This paper describes the new portable VISAR, its peripheral sensors, and the role it played in optically measuring ground shock of an underground nuclear detonation (UGT). The Solid State VISAR uses a prototype diode pumped Nd:YAG laser and solid state detectors that provide a suitcase-size system with low power requirements. A special window and sensors was developed for fiber optic coupling (1 kilometer long) to the VISCAR. The system has proven itself as reliable, easy to use instrument that is capable of field test use and rapid data reduction using only a notebook personal computer (PC).
Portable, solid state, fiber optic coupled Doppler interferometer system for detonation and shock diagnostics
Fleming, K.J.; Crump, O.B.
VISAR (Velocity Interferometer System for Any Reflector) is a specialized Doppler interferometer system that is gaining world-wide acceptance as the standard for shock phenomena analysis. The VISAR`s large power and cooling requirements, and the sensitive and complex nature of the interferometer cavity have restricted the traditional system to the laboratory. This paper describes the new portable VISAR, its peripheral sensors, and the role it played in optically measuring ground shock of an underground nuclear detonation. The solid State VISAR uses a prototype diode pumped ND:YAG laser and solid state detectors that provide a suitcase-size system with low power requirements. A special window and sensors were developed for fiber optic coupling (1 kilometer long) to the VISAR. The system has proven itself as a reliable, easy to use instrument that is capable of field test use and rapid data reduction using only a notebook personal computer (PC).
Portable, solid state, fiber optic coupled doppler interferometer system for detonation and shock diagnostics
Fleming, K.J.; Crump, O.B.
VISAR (Velocity Interferometer System for Any Reflector) is a specialized Doppler interferometer system that is gaining world-wide acceptance as the standard for shock phenomena analysis. The VISAR's large power and cooling requirements, and the sensitive and complex nature of the interferometer cavity has restricted the traditional system to the laboratory. This paper describes the new portable VISAR, its peripheral sensors, and the role it played in optically measuring ground shock of an underground nuclear detonation (UGT). The Solid State VISAR uses a prototype diode pumped ND:YAG laser and solid state detectors that provide a suitcase-size system with low power requirements. A special window and sensor was developed for fiber optic coupling (1 kilometer long) to the VISAR. The system has proven itself as a reliable, easy-to-use instrument that is capable of field test use and rapid data reduction employing only a personal computer (PC).
Theory of edge-state optical absorption in two-dimensional transition metal dichalcogenide flakes
NASA Astrophysics Data System (ADS)
Trushin, Maxim; Kelleher, Edmund J. R.; Hasan, Tawfique
We develop an analytical model to describe sub-band-gap optical absorption in two-dimensional semiconducting transition metal dichalcogenide (s-TMD) nanoflakes. The material system represents an array of few-layer molybdenum disulfide crystals, randomly orientated in a polymer matrix. We propose that optical absorption involves direct transitions between electronic edge states and bulk bands, depends strongly on the carrier population, and is saturable with sufficient fluence. For excitation energies above half the band gap, the excess energy is absorbed by the edge-state electrons, elevating their effective temperature. Our analytical expressions for the linear and nonlinear absorption could prove useful tools in the design of practical photonic devices based on s-TMDs.
Nature of electronic states and optical functions of sodium oxyanionic compounds
NASA Astrophysics Data System (ADS)
Zhuravlev, Yu. N.; Korabel'Nikov, D. V.
The band structure, the density of states, the partial electron densities, and optical functions (such as permittivity, refraction index, reflection and absorption coefficients) of sodium nitrite, nitrate, carbonate, chlorate, sulfite, perchlorate, and sulfate are calculated in a local approximation of the density-functional theory using the Troullier-Martins pseudopotentials in the basis of numerical pseudoatomic orbitals. The nature of the upper valence bands and the lower empty bands is established. It is shown that the specific features of the optical functions at energies of up to 8 eV and at E> 8 eV are due to the excitation of electrons into a localized anionic conduction band and into the bands of anion-cation states, respectively. The results are compared to experimental photoelectron spectra and reflection and absorption spectra.
Optical excitation of trapping states in Fe doped InP
NASA Astrophysics Data System (ADS)
Giessner, J.
The knowledge that defect states affect the performance and speed of semiconductors is well known. Defect and trapping states are categorized according to their sex (hole or electron trap), energy in the gap and capture cross sections. The Deep Level Transient Spectroscopy (DLTS) technique that is useful for electrical pulsing, becomes increasingly profitable using optical pulsing. The optical pulsing was accomplished using a simple, but efficient, infrared light emitting diode (LED). The LED had the fortunate property that with decreasing temperature, the average energy output of the LED stayed about equal to the bandgap for the 3-5 semiconductor InP. Because of these findings, emphasis was put on Fe-doped Inp using LED excitation. These particular samples are being studied by Naval Research Labs (NRL) in connection with lasing that results from Fe transitions. Models were set up for both the p+n junction and Fe transitions to help explain experimental results obtained.
Surface-modified Wannier-Stark states in a one-dimensional optical lattice
NASA Astrophysics Data System (ADS)
Maury, A.; Donaire, M.; Gorza, M.-P.; Lambrecht, A.; Guérout, R.
We study the energy spectrum of atoms trapped in a vertical one-dimensional optical lattice in close proximity to a reflective surface. We propose an effective model to describe the interaction between the atoms and the surface at any distance. Our model includes the long-range Casimir-Polder potential together with a short-range Lennard-Jones potential, which are considered nonperturbatively with respect to the optical lattice potential. We find an intricate energy spectrum which contains a pair of loosely bound states localized close to the surface in addition to a surface-modified Wannier-Stark ladder at long distances. Atomic interferometry involving those loosely bound atom-surface states is proposed to probe the adsorption dynamics of atoms on mirrors.
Nonlinear Sensing With Collective States of Ultracold Atoms in Optical Lattices
decimation algorithm , a method that takes into account quantum correlations. B.1. In collaboration with D. Blume and X.Y. Yin at Washington State...Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 Nonlinear quantum sensing, quantum metrology, ultracold atoms, optical lattices REPORT...with applications to interaction-based quantum metrology, Physical Review A, (10 2014): 0. doi: 10.1103/PhysRevA.90.041602 Khan W Mahmud, Lei Jiang
Creating Ground State Molecules with Optical Feshbach Resonances in Tight Traps
Koch, Christiane P.; Masnou-Seeuws, Francoise; Kosloff, Ronnie
We propose to create ultracold ground state molecules in an atomic Bose-Einstein condensate by adiabatic crossing of an optical Feshbach resonance. We envision a scheme where the laser intensity and possibly also frequency are linearly ramped over the resonance. Our calculations for {sup 87}Rb show that for sufficiently tight traps it is possible to avoid spontaneous emission while retaining adiabaticity, and conversion efficiencies of up to 50% can be expected.
Optical isolation in the LIGO gravitational wave laser detector in transient states
Soloviev, A A; Khazanov, Efim A
This paper presents a numerical analysis of the degree of optical isolation of the laser source by the Faraday isolator in transient states of the laser interferometer gravitational wave observatory (LIGO) detector. This system may be in transient states where the power of the light reflected from the detector to the laser source can exceed many times the power of the source. The present results can be used to analyse the need for installing an additional active mechanical isolation of the source and to evaluate its response time.
Optically induced effective mass renormalization: the case of graphite image potential states
Montagnese, M.; Pagliara, S.; Galimberti, G.; Dal Conte, S.; Ferrini, G.; van Loosdrecht, P. H. M.; Parmigiani, F.
Many-body interactions with the underlying bulk electrons determine the properties of confined electronic states at the surface of a metal. Using momentum resolved nonlinear photoelectron spectroscopy we show that one can tailor these many-body interactions in graphite, leading to a strong renormalization of the dispersion and linewidth of the image potential state. These observations are interpreted in terms of a basic self-energy model, and may be considered as exemplary for optically induced many-body interactions. PMID:27739489
Model of Laser-Induced Temperature Changes in Solid-State Optical Refrigerators
Model of laser-induced temperature changes in solid-state optical refrigerators W. M. Patterson,1,a M. Sheik- Bahae ,1 R. I . Epstein,2 and M. P...Applications of Laser Cooling of Sol- ids, edited by R. I . Epstein and M. Sheik- Bahae Wiley, Weinheim, 2009. 2W. Koechner, Solid-State Laser...2004. 19D. V. Seletskiy, S. D. Melgaard, S. Bigotta, A. Di Lieto, M. Tonelli, R. I . Epstein, and M. Sheik- Bahae , in Conference on Lasers and Electro
Description of the states of two-photon interference in an optical gating Michelson interferometer
NASA Astrophysics Data System (ADS)
Pongophas, Ekkarat; Sriklin, Watthana; Sinsarp, Asawin; Suwanna, Sujin; Chunwachirasiri, Withoon; Singhsomroje, Wisit
We investigate the interference of two photons in an optical gating Michelson interferometer. The phenomenon is studied using two different representations of photons: the space-time domain and a step-by-step two-photon state evolution. Both representations lead to identical results. The evolution analysis describes the result by the interference of four two-photon traveling states, whereas the space-time domain analysis reveals that the classical interference of the high-intensity light source is identical to two-photon interference in the quantum regime, except for a multiplicative factor of (n2), where n is the number of photons.
Optical phase information writing and storage in populations of metastable quantum states
Djotyan, G. P.; Sandor, N.; Bakos, J. S.; Soerlei, Zs.
We propose a scheme for robust writing and storage of optical phase information in populations of metastable states of the atoms with a tripod structure of levels by using frequency-chirped laser pulses. The method provides much longer storage times compared with the schemes based on the collective atomic spin coherences. A negligible excitation of the atom provides immunity to decoherence induced by decay of the excited states. The method is robust against small-to-medium variations in the laser pulse intensity and speed of the chirp and, being insensitive to resonance conditions, it is effective both in homogeneously and inhomogeneously broadened media.
Optical pumping and readout of bismuth hyperfine states in silicon for atomic clock applications
Saeedi, K.; Szech, M.; Dluhy, P.; Salvail, J.Z.; Morse, K.J.; Riemann, H.; Abrosimov, N.V.; Nötzel, N.; Litvinenko, K.L.; Murdin, B.N.; Thewalt, M.L.W.
The push for a semiconductor-based quantum information technology has renewed interest in the spin states and optical transitions of shallow donors in silicon, including the donor bound exciton transitions in the near-infrared and the Rydberg, or hydrogenic, transitions in the mid-infrared. The deepest group V donor in silicon, bismuth, has a large zero-field ground state hyperfine splitting, comparable to that of rubidium, upon which the now-ubiquitous rubidium atomic clock time standard is based. Here we show that the ground state hyperfine populations of bismuth can be read out using the mid-infrared Rydberg transitions, analogous to the optical readout of the rubidium ground state populations upon which rubidium clock technology is based. We further use these transitions to demonstrate strong population pumping by resonant excitation of the bound exciton transitions, suggesting several possible approaches to a solid-state atomic clock using bismuth in silicon, or eventually in enriched 28Si. PMID:25990870
Microwave control of atomic motional states in a spin-dependent optical lattice
NASA Astrophysics Data System (ADS)
Belmechri, Noomen; Förster, Leonid; Alt, Wolfgang; Widera, Artur; Meschede, Dieter; Alberti, Andrea
Spin-dependent optical potentials allow us to use microwave radiation to manipulate the motional state of trapped neutral atoms (Förster et al 2009 Phys. Rev. Lett. 103 233001). Here, we discuss this method in greater detail, comparing it to the widely employed Raman sideband coupling method. We provide a simplified model for sideband cooling in a spin-dependent potential, and we discuss it in terms of the generalized Lamb-Dicke parameter. Using a master equation formalism, we present a quantitative analysis of the cooling performance for our experiment, which can be generalized to other experimental settings. We additionally use microwave sideband transitions to engineer motional Fock states and coherent states, and we devise a technique for measuring the population distribution of the prepared states.
Electro-optical parameters in excited states of some spectrally active molecules
NASA Astrophysics Data System (ADS)
Benchea, Andreea Celia; Closca, Valentina; Rusu, Cristina Marcela; Morosanu, Cezarina; Dorohoi, Dana Ortansa
The spectral shifts measured in different solvents are expressed as functions of the solvent macroscopic parameters. The value of the correlation coefficient multiplying the functions of electric permittivity was determined by statistical means. The correlation coefficient depends on the electric dipole moment of the spectrally active molecules. The electro-optical parameters in the ground state of the solute molecules can be approximated by molecular modeling. The excited state parameters are usually estimated using the results obtained both by HyperChem Programme and solvatochromic study. The importance of this approximate method is that it offers information about of the excited state of solute molecule for which our measuring possibilities are very restrictive. The information about the excited electronic state is affected by the limits in which the theories of liquid solutions are developed. Our results refer to two molecules of vitamins from B class, namely B3 and B6.
Modeling and design of a new core-moderator assembly and neutron beam ports for the Penn State Breazeale Nuclear Reactor (PSBR)
NASA Astrophysics Data System (ADS)
Ucar, Dundar
This study is for modeling and designing a new reactor core-moderator assembly and new neutron beam ports that aimed to expand utilization of a new beam hall of the Penn State Breazeale Reactor (PSBR). The PSBR is a part of the Radiation Science and Engineering Facility (RSEC) and is a TRIGA MARK III type research reactor with a movable core placed in a large pool and is capable to produce 1MW output. This reactor is a pool-type reactor with pulsing capability up to 2000 MW for 10-20 msec. There are seven beam ports currently installed to the reactor. The PSBR's existing core design limits the experimental capability of the facility, as only two of the seven available neutron beam ports are usable. The finalized design features an optimized result in light of the data obtained from neutronic and thermal-hydraulics analyses as well as geometrical constraints. A new core-moderator assembly was introduced to overcome the limitations of the existing PSBR design, specifically maximizing number of available neutron beam ports and mitigating the hydrogen gamma contamination of the neutron beam channeled in the beam ports. A crescent-shaped moderator is favored in the new PSBR design since it enables simultaneous use of five new neutron beam ports in the facility. Furthermore, the crescent shape sanctions a coupling of the core and moderator, which reduces the hydrogen gamma contamination significantly in the new beam ports. A coupled MURE and MCNP5 code optimization analysis was performed to calculate the optimum design parameters for the new PSBR. Thermal-hydraulics analysis of the new design was achieved using ANSYS Fluent CFD code. In the current form, the PSBR is cooled by natural convection of the pool water. The driving force for the natural circulation of the fluid is the heat generation within the fuel rods. The convective heat data was generated at the reactor's different operating powers by using TRIGSIMS, the fuel management code of the PSBR core. In the CFD
Generation of optical `Schrödinger cats' from photon number states
NASA Astrophysics Data System (ADS)
Ourjoumtsev, Alexei; Jeong, Hyunseok; Tualle-Brouri, Rosa; Grangier, Philippe
Schrödinger's cat is a Gedankenexperiment in quantum physics, in which an atomic decay triggers the death of the cat. Because quantum physics allow atoms to remain in superpositions of states, the classical cat would then be simultaneously dead and alive. By analogy, a `cat' state of freely propagating light can be defined as a quantum superposition of well separated quasi-classical states-it is a classical light wave that simultaneously possesses two opposite phases. Such states play an important role in fundamental tests of quantum theory and in many quantum information processing tasks, including quantum computation, quantum teleportation and precision measurements. Recently, optical Schrödinger `kittens' were prepared; however, they are too small for most of the aforementioned applications and increasing their size is experimentally challenging. Here we demonstrate, theoretically and experimentally, a protocol that allows the generation of arbitrarily large squeezed Schrödinger cat states, using homodyne detection and photon number states as resources. We implemented this protocol with light pulses containing two photons, producing a squeezed Schrödinger cat state with a negative Wigner function. This state clearly exhibits several quantum phase-space interference fringes between the `dead' and `alive' components, and is large enough to become useful for quantum information processing and experimental tests of quantum theory.
Effect of Aerosol Size and Hygroscopicity on Aerosol Optical Depth in the Southeastern United States
NASA Astrophysics Data System (ADS)
Brock, Charles; Wagner, Nick; Gordon, Timothy
Aerosol optical depth (AOD) is affected by the size, optical characteristics, and hygroscopicity of particles, confounding attempts to link remote sensing observations of AOD to measured or modeled aerosol mass concentrations. In situ airborne observations of aerosol optical, chemical, microphysical and hygroscopic properties were made in the southeastern United States in the daytime in summer 2013. We use these observations to constrain a simple model that is used to test the sensitivity of AOD to the various measured parameters. As expected, the AOD was found to be most sensitive to aerosol mass concentration and to aerosol water content, which is controlled by aerosol hygroscopicity and the ambient relative humidity. However, AOD was also fairly sensitive to the mean particle diameter and the width of the size distribution. These parameters are often prescribed in global models that use simplified modal parameterizations to describe the aerosol, suggesting that the values chosen could substantially bias the calculated relationship between aerosol mass and optical extinction, AOD, and radiative forcing.
Space-bound optical source for satellite-ground decoy-state quantum key distribution.
Li, Yang; Liao, Sheng-Kai; Chen, Xie-Le; Chen, Wei; Cheng, Kun; Cao, Yuan; Yong, Hai-Lin; Wang, Tao; Yang, Hua-Qiang; Liu, Wei-Yue; Yin, Juan; Liang, Hao; Peng, Cheng-Zhi; Pan, Jian-Wei
Satellite-ground quantum key distribution has embarked on the stage of engineering implementation, and a global quantum-secured network is imminent in the foreseeable future. As one payload of the quantum-science satellite which will be ready before the end of 2015, we report our recent work of the space-bound decoy-state optical source. Specialized 850 nm laser diodes have been manufactured and the integrated optical source has gotten accomplished based on these LDs. The weak coherent pulses produced by our optical source feature a high clock rate of 100 MHz, intensity stability of 99.5%, high polarization fidelity of 99.7% and phase randomization. A series of space environment tests have been conducted to verify the optical source's performance and the results are satisfactory. The emulated final secure keys are about 120 kbits during one usable pass of the low Earth orbit satellite. This work takes a significant step forward towards satellite-ground QKD and the global quantum-secured network.
Optical transitions from the lowest to higher exciton and biexciton Rydberg states in CuCl
NASA Astrophysics Data System (ADS)
Miyajima, K.; Sakaniwa, K.; Sugawara, M.
We measured the optical transitions due to the internal energy levels of an exciton and biexciton in a CuCl single crystal using pump-probe spectroscopy. The transient absorption bands due to the transitions from the 1 s to 2 p and from the 1 s to 3 p exciton states were observed at 3 K, which is consistent with their reported energies. Simultaneously, the transient absorption peak due to the biexciton was observed, which corresponds to a transition from the lowest state (composed of two 1 s excitons) to higher states (composed of 1 s and 2 p excitons). The value of the observed biexciton peak energy was reasonable considering the hydrogen molecule orbitals and the electron-to-hole effective mass ratio. In addition, the transient absorption peaks were broadened at 77 K, because of the increase in the homogeneous width of the 2 p exciton state. The transient absorption spectrum was almost completely determined by this width. Our findings are of importance with regard to the optical phenomena in the infrared region related to the quantum coherence of excitons and biexcitons in semiconductors.
The users, uses, and value of Landsat and other moderate-resolution satellite imagery in the United States-Executive report
Miller, Holly M.; Sexton, Natalie R.; Koontz, Lynne; Loomis, John; Koontz, Stephen R.; Hermans, Caroline
Moderate-resolution imagery (MRI), such as that provided by the Landsat satellites, provides unique spatial information for use by many people both within and outside of the United States (U.S.). However, exactly who these users are, how they use the imagery, and the value and benefits derived from the information are, to a large extent, unknown. To explore these issues, social scientists at the USGS Fort Collins Science Center conducted a study of U.S.-based MRI users from 2008 through 2010 in two parts: 1) a user identification and 2) a user survey. The objectives for this study were to: 1) identify and classify U.S.-based users of this imagery; 2) better understand how and why MRI, and specifically Landsat, is being used; and 3) qualitatively and quantitatively measure the value and societal benefits of MRI (focusing on Landsat specifically). The results of the survey revealed that respondents from multiple sectors use Landsat imagery in many different ways, as demonstrated by the breadth of project locations and scales, as well as application areas. The value of Landsat imagery to these users was demonstrated by the high importance placed on the imagery, the numerous benefits received from projects using Landsat imagery, the negative impacts if Landsat imagery was no longer available, and the substantial willingness to pay for replacement imagery in the event of a data gap. The survey collected information from users who are both part of and apart from the known user community. The diversity of the sample delivered results that provide a baseline of knowledge about the users, uses, and value of Landsat imagery. While the results supply a wealth of information on their own, they can also be built upon through further research to generate a more complete picture of the population of Landsat users as a whole.
Optimal mode transformations for linear-optical cluster-state generation
Uskov, Dmitry B.; Lougovski, Pavel; Alsing, Paul M.; Fanto, Michael L.; Kaplan, Lev; Smith, Amos Matthew
In this paper, we analyze the generation of linear-optical cluster states (LOCSs) via sequential addition of one and two qubits. Existing approaches employ the stochastic linear-optical two-qubit controlled-Z (CZ) gate with success rate of 1/9 per operation. The question of optimality of the CZ gate with respect to LOCS generation has remained open. We report that there are alternative schemes to the CZ gate that are exponentially more efficient and show that sequential LOCS growth is indeed globally optimal. We find that the optimal cluster growth operation is a state transformation on a subspace of the full Hilbert space. Finally, we show that the maximal success rate of postselected entangling n photonic qubits or m Bell pairs into a cluster is (1/2)n-1 and (1/4)m-1, respectively, with no ancilla photons, and we give an explicit optical description of the optimal mode transformations.
Optimal mode transformations for linear-optical cluster-state generation
Uskov, Dmitry B.; Lougovski, Pavel; Alsing, Paul M.; ...
In this paper, we analyze the generation of linear-optical cluster states (LOCSs) via sequential addition of one and two qubits. Existing approaches employ the stochastic linear-optical two-qubit controlled-Z (CZ) gate with success rate of 1/9 per operation. The question of optimality of the CZ gate with respect to LOCS generation has remained open. We report that there are alternative schemes to the CZ gate that are exponentially more efficient and show that sequential LOCS growth is indeed globally optimal. We find that the optimal cluster growth operation is a state transformation on a subspace of the full Hilbert space. Finally,more » we show that the maximal success rate of postselected entangling n photonic qubits or m Bell pairs into a cluster is (1/2)n-1 and (1/4)m-1, respectively, with no ancilla photons, and we give an explicit optical description of the optimal mode transformations.« less
A Single Intravitreal Injection of Ranibizumab Provides No Neuroprotection in a Nonhuman Primate Model of Moderate-to-Severe Nonarteritic Anterior Ischemic Optic Neuropathy
Miller, Neil R.; Johnson, Mary A.; Nolan, Theresa; Guo, Yan; Bernstein, Steven L.
Purpose Ranibizumab, a vascular endothelial growth factor-antagonist, is said to be neuroprotective when injected intravitreally in patients with nonarteritic anterior ischemic optic neuropathy (NAION). We evaluated the efficacy of a single intravitreal (IVT) injection of ranibizumab in a nonhuman primate model of NAION (pNAION). Methods We induced pNAION in one eye of four adult male rhesus monkeys using a laser-activated rose Bengal induction method. We then immediately injected the eye with either ranibizumab or normal saline (NS) intravitreally. We performed a clinical assessment, optical coherence tomography, electrophysiological testing, fundus photography, and fluorescein angiography in three of the animals (one animal developed significant retinal hemorrhages and, therefore, could not be analyzed completely) prior to induction, 1 day and 1, 2, and 4 weeks thereafter. Following the 4-week analysis of the first eye, we induced pNAION in the contralateral eye and then injected either ranibizumab or NS, whichever substance had not been injected in the first eye. We euthanized all animals 5 to 12 weeks after the final assessment of the second eye and performed both immunohistochemical and light and electron microscopic analyses of the retina and optic nerves of both eyes. Results A single IVT dose of ranibizumab administered immediately after induction of pNAION resulted in no significant reduction of clinical, electrophysiological, or histologic damage compared with vehicle-injected eyes. Conclusions A single IVT dose of ranibizumab is not neuroprotective when administered immediately after induction of pNAION. PMID:26624498
Description of states of two-photon interference in optical gating Michelson interferometer
NASA Astrophysics Data System (ADS)
Pongophas, Ekkarat; Sinsarp, Asawin; Suwanna, Sujin; Chunwachirasiri, Withoon; Singhsomroje, Wisit
The interference of two photons in the optical gating Michelson interferometer is investigated. The phenomenon is studied using two different representations of photons: the space-time domain and a step-by-step two photon state evolution. Both representations lead to an equivalent description of the two-photon states which is the interference of four cases of two-photon traveling states, as implied by the evolution analysis. Additionally, the space-time domain analysis reveals that the classical interference of high-intensity light source is identical to the two-photon interference in the quantum regime except for a multiplicative factor of (n 2), where n is the number of photons.
Formation of ultracold polar ground state molecules via an optical process
NASA Astrophysics Data System (ADS)
Dulieu, Olivier; Borsalino, Dimitri; Orban, Andrea; Vexiau, Romain; Londono-Florez, Beatriz; Crubellier, Anne; Luc, Eliane; Bouloufa-Maafa, Nadia
Based on spectroscopic studies available in the literature completed by accurate ab initio calculations for potentail energy curves, spin-orbit couplings, and transition dipole moments, we investigate several optical coherent schemes to create ultracold bosonic and fermionic ultracold polar molecules in their absolute rovibrational ground level, starting from a weakly bound level of their electronic ground state manifold. The processes rely on the existence of convenient electronically excited states allowing an efficient stimulated Raman adiabatic transfer (STIRAP) of the level population. Illustrations are given for KRb and KCs. A model for the hyperfine structure of the excited molecular states is also presented. Supported by Agence Nationale de la Recherche (ANR), project COPOMOL (# ANR-13-IS04-0004-01).
Coherent manipulation, measurement and entanglement of individual solid-state spins using optical fields
NASA Astrophysics Data System (ADS)
Gao, W. B.; Imamoglu, A.; Bernien, H.; Hanson, R.
Realization of a quantum interface between stationary and flying qubits is a requirement for long-distance quantum communication and distributed quantum computation. The prospects for integrating many qubits on a single chip render solid-state spins promising candidates for stationary qubits. Certain solid-state systems, including quantum dots and nitrogen-vacancy centres in diamond, exhibit spin-state-dependent optical transitions, allowing for fast initialization, manipulation and measurement of the spins using laser excitation. Recent progress has brought spin photonics research in these materials into the quantum realm, allowing the demonstration of spin-photon entanglement, which in turn has enabled distant spin entanglement as well as quantum teleportation. Advances in the fabrication of photonic nanostructures hosting spin qubits suggest that chips incorporating a high-efficiency spin-photon interface in a quantum photonic network are within reach.
Quantum-state tomography of a single nuclear spin qubit of an optically manipulated ytterbium atom
Noguchi, Atsushi; Kozuma, Mikio; Eto, Yujiro; Ueda, Masahito
A single Yb atom is loaded into a high-finesse optical cavity with a moving lattice, and its nuclear spin state is manipulated using a nuclear magnetic resonance technique. A highly reliable quantum state control with fidelity and purity greater than 0.98 and 0.96, respectively, is confirmed by the full quantum state tomography; a projective measurement with high speed (500 {mu}s) and high efficiency (0.98) is accomplished using the cavity QED technique. Because a hyperfine coupling is induced only when the projective measurement is operational, the long coherence times (T{sub 1}=0.49 s and T{sub 2}=0.10 s) are maintained.
Critical field enhancement of asymptotic optical bound states in the continuum
Yoon, Jae Woong; Song, Seok Ho; Magnusson, Robert
We study spectral singularities and critical field enhancement factors associated with embedded photonic bound states in subwavelength periodic Si films. Ultrahigh-Q resonances supporting field enhancement factor exceeding 108 are obtained in the spectral vicinity of exact embedded eigenvalues in spite of deep surface modulation and vertical asymmetry of the given structure. Treating relations between the partial resonance Q and field enhancement factors with an analytical coupled-mode model, we derive a general strategy to maximize the field enhancement associated with these photonic bound states in the presence of material dissipation. The analytical expression for the field enhancement quantitatively agrees with rigorous numerical calculations. Therefore, our results provide a general knowledge for designing practical resonance elements based on optical bound states in the continuum in various applications. PMID:26673548
Factorizable state-space model for active optical filter structures with two-port couplers.
Panahi, Issa; Kannan, Govind
A state-space model (SSM) is developed for an integrated photonic architecture. This particular architecture is composed of two-port couplers and current-controllable semiconductor optical amplifiers (gains) fabricated on the same substrate. This device architecture leads to a new type of lattice filter structure. The SSM is shown to be factorizable into two matrices, one containing structural parameters of the two-port couplers, which are set during manufacturing, and the other containing the tunable gains. The SSM provides a systematic and practical approach to the analysis of the underlying filter structure, which can be easily extended to multiple-input, multiple-output optical filter structures with or without adjustable gains using two- or four-port couplers. A novel method of using the gains as loss compensation elements in addition to their tunable roles is developed.
Optical Sensing of the Fatigue Damage State of CFRP under Realistic Aeronautical Load Sequences
Zuluaga-Ramírez, Pablo; Arconada, Álvaro; Frövel, Malte; Belenguer, Tomás; Salazar, Félix
We present an optical sensing methodology to estimate the fatigue damage state of structures made of carbon fiber reinforced polymer (CFRP), by measuring variations on the surface roughness. Variable amplitude loads (VAL), which represent realistic loads during aeronautical missions of fighter aircraft (FALSTAFF) have been applied to coupons until failure. Stiffness degradation and surface roughness variations have been measured during the life of the coupons obtaining a Pearson correlation of 0.75 between both variables. The data were compared with a previous study for Constant Amplitude Load (CAL) obtaining similar results. Conclusions suggest that the surface roughness measured in strategic zones is a useful technique for structural health monitoring of CFRP structures, and that it is independent of the type of load applied. Surface roughness can be measured in the field by optical techniques such as speckle, confocal perfilometers and interferometry, among others. PMID:25760056
Optical sensing of the fatigue damage state of CFRP under realistic aeronautical load sequences.
Zuluaga-Ramírez, Pablo; Arconada, Álvaro; Frövel, Malte; Belenguer, Tomás; Salazar, Félix
We present an optical sensing methodology to estimate the fatigue damage state of structures made of carbon fiber reinforced polymer (CFRP), by measuring variations on the surface roughness. Variable amplitude loads (VAL), which represent realistic loads during aeronautical missions of fighter aircraft (FALSTAFF) have been applied to coupons until failure. Stiffness degradation and surface roughness variations have been measured during the life of the coupons obtaining a Pearson correlation of 0.75 between both variables. The data were compared with a previous study for Constant Amplitude Load (CAL) obtaining similar results. Conclusions suggest that the surface roughness measured in strategic zones is a useful technique for structural health monitoring of CFRP structures, and that it is independent of the type of load applied. Surface roughness can be measured in the field by optical techniques such as speckle, confocal perfilometers and interferometry, among others.
Implementing general quantum measurements on linear optical and solid-state qubits
NASA Astrophysics Data System (ADS)
Ota, Yukihiro; Ashhab, Sahel; Nori, Franco
We show a systematic construction for implementing general measurements on a single qubit, including both strong (or projection) and weak measurements. We mainly focus on linear optical qubits. The present approach is composed of simple and feasible elements, i.e., beam splitters, wave plates, and polarizing beam splitters. We show how the parameters characterizing the measurement operators are controlled by the linear optical elements. We also propose a method for the implementation of general measurements in solid-state qubits. Furthermore, we show an interesting application of the general measurements, i.e., entanglement amplification. YO is partially supported by the SPDR Program, RIKEN. SA and FN acknowledge ARO, NSF grant No. 0726909, JSPS-RFBR contract No. 12-02-92100, Grant-in-Aid for Scientific Research (S), MEXT Kakenhi on Quantum Cybernetics, and the JSPS via its FIRST program.
New Method for Characterizing the State of Optical and Opto-Mechanical Systems
NASA Technical Reports Server (NTRS)
Keski-Kuha, Ritva; Saif, Babak; Feinberg, Lee; Chaney, David; Bluth, Marcel; Greenfield, Perry; Hack, Warren; Smith, Scott; Sanders, James
James Webb Space Telescope Optical Telescope Element (OTE) is a three mirror anastigmat consisting of a 6.5 m primary mirror (PM), secondary mirror (SM) and a tertiary mirror. The primary mirror is made out of 18 segments. The telescope and instruments will be assembled at Goddard Space Flight Center (GSFC) to make it the Optical Telescope Element-Integrated Science Instrument Module (OTIS). The OTIS will go through environmental testing at GSFC before being transported to Johnson Space Center for testing at cryogenic temperature. The objective of the primary mirror Center of Curvature test (CoC) is to characterize the PM before and after the environmental testing for workmanship. This paper discusses the CoC test including both a surface figure test and a new method for characterizing the state of the primary mirror using high speed dynamics interferometry.
The impact of quantum dot filling on dual-band optical transitions via intermediate quantum states
Wu, Jiang; Passmore, Brandon; Manasreh, M. O.
InAs/GaAs quantum dot infrared photodetectors with different doping levels were investigated to understand the effect of quantum dot filling on both intraband and interband optical transitions. The electron filling of self-assembled InAs quantum dots was varied by direct doping of quantum dots with different concentrations. Photoresponse in the near infrared and middle wavelength infrared spectral region was observed from samples with low quantum dot filling. Although undoped quantum dots were favored for interband transitions with the absence of a second optical excitation in the near infrared region, doped quantum dots were preferred to improve intraband transitions in the middle wavelength infrared region. As a result, partial filling of quantum dot was required, to the extent of maintaining a low dark current, to enhance the dual-band photoresponse through the confined electron states.
The binary millisecond pulsar PSR J1023+0038 during its accretion state - I. Optical variability
NASA Astrophysics Data System (ADS)
Shahbaz, T.; Linares, M.; Nevado, S. P.; Rodríguez-Gil, P.; Casares, J.; Dhillon, V. S.; Marsh, T. R.; Littlefair, S.; Leckngam, A.; Poshyachinda, S.
We present time-resolved optical photometry of the binary millisecond `redback' pulsar PSR J1023+0038 (=AY Sex) during its low-mass X-ray binary phase. The light curves taken between 2014 January and April show an underlying sinusoidal modulation due to the irradiated secondary star and accretion disc. We also observe superimposed rapid flaring on time-scales as short as ˜20 s with amplitudes of ˜0.1-0.5 mag and additional large flare events on time-scales of ˜5-60 min with amplitudes of ˜0.5-1.0 mag. The power density spectrum of the optical flare light curves is dominated by a red-noise component, typical of aperiodic activity in X-ray binaries. Simultaneous X-ray and UV observations by the Swift satellite reveal strong correlations that are consistent with X-ray reprocessing of the UV light, most likely in the outer regions of the accretion disc. On some nights we also observe sharp-edged, rectangular, flat-bottomed dips randomly distributed in orbital phase, with a median duration of ˜250 s and a median ingress/egress time of ˜20 s. These rectangular dips are similar to the mode-switching behaviour between disc `active' and `passive' luminosity states, observed in the X-ray light curves of other redback millisecond pulsars. This is the first time that the optical analogue of the X-ray mode-switching has been observed. The properties of the passive- and active-state light curves can be explained in terms of clumpy accretion from a trapped inner accretion disc near the corotation radius, resulting in rectangular, flat-bottomed optical and X-ray light curves.
Stacked bilayer phosphorene: strain-induced quantum spin Hall state and optical measurement
Zhang, Tian; Lin, Jia-He; Yu, Yan-Mei; Chen, Xiang-Rong; Liu, Wu-Ming
Bilayer phosphorene attracted considerable interest, giving a potential application in nanoelectronics owing to its natural bandgap and high carrier mobility. However, very little is known regarding the possible usefulness in spintronics as a quantum spin Hall (QSH) state of material characterized by a bulk energy gap and gapless spin-filtered edge states. Here, we report a strain-induced topological phase transition from normal to QSH state in bilayer phosphorene, accompanied by band-inversion that changes number from 0 to 1, which is highly dependent on interlayer stacking. When the bottom layer is shifted by 1/2 unit-cell along zigzag/armchair direction with respect to the top layer, the maximum topological bandgap 92.5 meV is sufficiently large to realize QSH effect even at room-temperature. An optical measurement of QSH effect is therefore suggested in view of the wide optical absorption spectrum extending to far infra-red, making bilayer phosphorene a promising candidate for opto-spintronic devices. PMID:26370771
Controlling the volatility of the written optical state in electrochromic DNA liquid crystals
Liu, Kai; Varghese, Justin; Gerasimov, Jennifer Y.; Polyakov, Alexey O.; Shuai, Min; Su, Juanjuan; Chen, Dong; Zajaczkowski, Wojciech; Marcozzi, Alessio; Pisula, Wojciech; Noheda, Beatriz; Palstra, Thomas T. M.; Clark, Noel A.; Herrmann, Andreas
Liquid crystals are widely used in displays for portable electronic information display. To broaden their scope for other applications like smart windows and tags, new material properties such as polarizer-free operation and tunable memory of a written state become important. Here, we describe an anhydrous nanoDNA–surfactant thermotropic liquid crystal system, which exhibits distinctive electrically controlled optical absorption, and temperature-dependent memory. In the liquid crystal isotropic phase, electric field-induced colouration and bleaching have a switching time of seconds. Upon transition to the smectic liquid crystal phase, optical memory of the written state is observed for many hours without applied voltage. The reorientation of the DNA–surfactant lamellar layers plays an important role in preventing colour decay. Thereby, the volatility of optoelectronic state can be controlled simply by changing the phase of the material. This research may pave the way for developing a new generation of DNA-based, phase-modulated, photoelectronic devices. PMID:27157494
Spin-patterned plasmonics: towards optical access to topological-insulator surface states.
Spektor, Grisha; David, Asaf; Bartal, Guy; Orenstein, Meir; Hayat, Alex
Topological insulators (TI) are new phases of matter with topologically protected surface states (SS) possessing novel physical properties such as spin-momentum locking. Coupling optical angular momentum to the SS is of interest for both fundamental understanding and applications in future spintronic devices. However, due to the nanoscale thickness of the surface states, the light matter interaction is dominated by the bulk. Here we propose and experimentally demonstrate a plasmonic cavity enabling both nanoscale light confinement and control of surface plasmon-polariton (SPP) spin angular momentum (AM)--towards coupling to topological-insulator SS. The resulting SPP field components within the cavity are arranged in a chess-board-like pattern. Each chess-board square exhibits approximately a uniform circular polarization (spin AM) of the local in-plane field interleaved by out-of-plane field vortices (orbital AM). As the first step, we demonstrate the predicted pattern experimentally by near-field measurements on a gold-air interface, with excellent agreement to our theory. Our results pave the way towards efficient optical access to topological-insulator surface states using plasmonics.
Coherent Excitation of Lithium to Rydberg States and Application to Rydberg Atom Optics
NASA Astrophysics Data System (ADS)
Stevens, G.; Widmer, M.; Tudorica, F.; Iu, C.-H.; Metcalf, H.
We present a theoretical analysis of several schemes for coherently exciting lithium atoms in a thermal beam to Rydberg states in a four level/three laser system, previously discussed by Oreg et al.(J. Oreg et al.), Phys. Rev. A 45, 4888 (1992). The time evolution of the dressed states and their populations are calculated numerically, solving the optical Bloch equations by a fourth order Runge-Kutta integration. Our code closely models actual experimental conditions, including spontaneous decay, beam profiles, intensities and detunings. Large Rydberg populations (50%) around n=15 may be obtained by non-adiabatic excitation, with each laser power on the order of 1 mW. We discuss the effects of an externally controlled time dependent detuning in the Rydberg state, for example as produced by atoms traversing an inhomogeneous electric field. An understanding of this excitation mechanism is important for large angle reflection of coherently excited atoms using field gradients. Some primitive ideas of Stark-Rydberg atom optics are presented.
Study on photonic angular momentum states in coaxial magneto-optical waveguides
Yang, Mu; Wu, Li-Ting; Guo, Tian-Jing; Guo, Rui-Peng; Cui, Hai-Xu; Cao, Xue-Wei; Chen, Jing
By rigorously solving Maxwell's equations, we develop a full-wave electromagnetic theory for the study of photonic angular momentum states (PAMSs) in coaxial magneto-optical (MO) waveguides. Paying attention to a metal-MO-metal coaxial configuration, we show that the dispersion curves of the originally degenerated PAMSs experience a splitting, which are determined by the off-diagonal permittivity tensor element of the MO medium. We emphasize that this broken degeneracy in dispersion relation is accompanied by modified distributions of field component and transverse energy flux. A qualitative analysis about the connection between the split dispersion behavior and the field distribution is provided. Potential applications are discussed.
Metasurface Polarization Optics: Independent Phase Control of Arbitrary Orthogonal States of Polarization.
Balthasar Mueller, J P; Rubin, Noah A; Devlin, Robert C; Groever, Benedikt; Capasso, Federico
We present a method allowing for the imposition of two independent and arbitrary phase profiles on any pair of orthogonal states of polarization-linear, circular, or elliptical-relying only on simple, linearly birefringent wave plate elements arranged into metasurfaces. This stands in contrast to previous designs which could only address orthogonal linear, and to a limited extent, circular polarizations. Using this approach, we demonstrate chiral holograms characterized by fully independent far fields for each circular polarization and elliptical polarization beam splitters, both in the visible. This approach significantly expands the scope of metasurface polarization optics.
Metasurface Polarization Optics: Independent Phase Control of Arbitrary Orthogonal States of Polarization
NASA Astrophysics Data System (ADS)
Balthasar Mueller, J. P.; Rubin, Noah A.; Devlin, Robert C.; Groever, Benedikt; Capasso, Federico
We present a method allowing for the imposition of two independent and arbitrary phase profiles on any pair of orthogonal states of polarization—linear, circular, or elliptical—relying only on simple, linearly birefringent wave plate elements arranged into metasurfaces. This stands in contrast to previous designs which could only address orthogonal linear, and to a limited extent, circular polarizations. Using this approach, we demonstrate chiral holograms characterized by fully independent far fields for each circular polarization and elliptical polarization beam splitters, both in the visible. This approach significantly expands the scope of metasurface polarization optics.
Efficient out-coupling and beaming of Tamm optical states via surface plasmon polariton excitation
Lopez-Garcia, M.; Ho, Y.-L. D.; Taverne, M. P. C.; Chen, L.-F.; Rarity, J. G.; Oulton, R.; Murshidy, M. M.; Edwards, A. P.; Adawi, A. M.; Serry, M. Y.
We present evidence of optical Tamm states to surface plasmon polariton (SPP) coupling. We experimentally demonstrate that for a Bragg stack with a thin metal layer on the surface, hybrid Tamm-SPP modes may be excited when a grating on the air-metal interface is introduced. Out-coupling via the grating to free space propagation is shown to enhance the transmission as well as the directionality and polarization selection for the transmitted beam. We suggest that this system will be useful on those devices, where a metallic electrical contact as well as beaming and polarization control is needed.
Measurements of the nonradiative states of optically illuminated semiconductors by a superconducting tunnel junction
Iguchi, I.; Kasai, Y.
A novel technique which utilizes a superconducting tunnel junction as a phonon detector is introduced to detect nonequilibrium phonons from the nonradiative states in optically illuminated semiconductors such as Si or GaAs. The method proved to have very high sensitivity for phonon detection with a large S-italic/N-italic ratio. The detected phonon signal as a function of wavelength of the light for GaAs exhibited modulated structures below the band-gap energy consistent with the presence of an EL2 level.
Long-distance decoy-state quantum key distribution in optical fiber.
Rosenberg, Danna; Harrington, Jim W; Rice, Patrick R; Hiskett, Philip A; Peterson, Charles G; Hughes, Richard J; Lita, Adriana E; Nam, Sae Woo; Nordholt, Jane E
The theoretical existence of photon-number-splitting attacks creates a security loophole for most quantum key distribution (QKD) demonstrations that use a highly attenuated laser source. Using ultralow-noise, high-efficiency transition-edge sensor photodetectors, we have implemented the first version of a decoy-state protocol that incorporates finite statistics without the use of Gaussian approximations in a one-way QKD system, enabling the creation of secure keys immune to photon-number-splitting attacks and highly resistant to Trojan horse attacks over 107 km of optical fiber.
Temporal model of an optically pumped co-doped solid state laser
NASA Technical Reports Server (NTRS)
Wangler, T. G.; Swetits, J. J.; Buoncristiani, A. M.
Currently, research is being conducted on the optical properties of materials associated with the development of solid state lasers in the two micron region. In support of this effort, a mathematical model describing the energy transfer in a holmium laser sensitized with thulium is developed. In this paper, we establish some qualitative properties of the solution of the model, such as non-negativity, boundedness, and integrability. A local stability analysis is then performed from which conditions for asymptotic stability are attained. Finally, we report on our numerical analysis of the system and how it compares with experimental results.
Efficient out-coupling and beaming of Tamm optical states via surface plasmon polariton excitation
NASA Astrophysics Data System (ADS)
Lopez-Garcia, M.; Ho, Y.-L. D.; Taverne, M. P. C.; Chen, L.-F.; Murshidy, M. M.; Edwards, A. P.; Serry, M. Y.; Adawi, A. M.; Rarity, J. G.; Oulton, R.
We present evidence of optical Tamm states to surface plasmon polariton (SPP) coupling. We experimentally demonstrate that for a Bragg stack with a thin metal layer on the surface, hybrid Tamm-SPP modes may be excited when a grating on the air-metal interface is introduced. Out-coupling via the grating to free space propagation is shown to enhance the transmission as well as the directionality and polarization selection for the transmitted beam. We suggest that this system will be useful on those devices, where a metallic electrical contact as well as beaming and polarization control is needed.
Coherence properties and quantum state transportation in an optical conveyor belt.
Kuhr, S; Alt, W; Schrader, D; Dotsenko, I; Miroshnychenko, Y; Rosenfeld, W; Khudaverdyan, M; Gomer, V; Rauschenbeutel, A; Meschede, D
We have prepared and detected quantum coherences of trapped cesium atoms with long dephasing times. Controlled transport by an "optical conveyor belt" over macroscopic distances preserves the atomic coherence with slight reduction of coherence time. The limiting dephasing effects are experimentally identified, and we present an analytical model of the reversible and irreversible dephasing mechanisms. Our experimental methods are applicable at the single-atom level. Coherent quantum bit operations along with quantum state transport open the route towards a "quantum shift register" of individual neutral atoms.
Effect of wetting-layer density of states on the gain and phase recovery dynamics of quantum-dot semiconductor optical amplifiers
NASA Astrophysics Data System (ADS)
Kim, Jungho; Yu, Bong-Ahn
We numerically investigate the effect of the wetting-layer (WL) density of states on the gain and phase recovery dynamics of quantum-dot semiconductor optical amplifiers in both electrical and optical pumping schemes by solving 1088 coupled rate equations. The temporal variations of the ultrafast gain and phase recovery responses at the ground state (GS) are calculated as a function of the WL density of states. The ultrafast gain recovery responses do not significantly depend on the WL density of states in the electrical pumping scheme and the three optical pumping schemes such as the optical pumping to the WL, the optical pumping to the excited state ensemble, and the optical pumping to the GS ensemble. The ultrafast phase recovery responses are also not significantly affected by the WL density of states except the optical pumping to the WL, where the phase recovery component caused by the WL becomes slowed down as the WL density of states increases.
Optical Properties of the Defect State Luminescence of Zn2 SnO4 Nanowires
NASA Astrophysics Data System (ADS)
Yakami, Baichhabi; Paudyal, Uma; Nandyala, Shashank; Rimal, Gaurab; Cooper, Jason K.; Chen, Jiajun; Chien, Teyu; Wang, Wenyong; Pikal, Jon M.; Department of Electrical; Computer Engineering Team; Department of Physics; Astronomy Team
Nanowires (NWs) are a promising option for sensitized solar cells, sensors & display technology. Most of the work thus far has focused on binary oxides for these NWs, but ternary oxides have advantages in additional control of optical and electronic properties. Here we report on the diffuse reflectance, Low Temperature (LT) and Room Temperature (RT) photoluminescence (PL), PL excitation and Time Resolved PL (TRPL) of Zinc Tin Oxide (ZTO) NWs grown by Chemical Vapor Deposition. Our results show two broad peaks centered at 640 nm & 450 nm. The complex emission spectra was studied by Time Resolved Emission Spectroscopy (TRES) and Intensity dependent PL. The intensity dependent TRPL shows that 640 nm states decay much slower than the 450 nm states. We propose an energy band model for the NWs containing donor and acceptor states in the band gap with the associated transitions between these states that are consistent with our results. The effect of annealing in air and vacuum is carried out to study the origin of defect states in these NWs. . Department of Energy.
Realizing artificial spin ice states for magnetic colloids on optical trap arrays
NASA Astrophysics Data System (ADS)
Libál, A.; Reichhardt, C. M.; Olson Reichhardt, C. J.
Colloids interacting with periodic substrates such as those created with optical traps are an ideal system in which to study various types of phase transitions such as commensurate to incommensurate states and melting behaviors, and they can also be used to create new types of ordering that can be mapped to spin systems. Here we numerically demonstrate how magnetic colloids interacting with an array of elongated two-state traps can be used to realize square artificial spin ice. By tuning the magnetic field, it is possible to precisely control the interaction strength between the colloids, making it possible to observe a transition from a disordered state to an ordered state that obeys the two-in/two-out ice rules. We also examine the dynamics of excitations of the ground state, including pairs of monopoles, and show that the monopoles have emergent attractive interactions. The strength of the interaction can be modified by the magnetic field, permitting the monopole velocity to be tuned.
Optical cooling of AlH+ to the rotational ground state
NASA Astrophysics Data System (ADS)
Lien, Chien-Yu; Seck, Christopher; Odom, Brian
We demonstrate cooling of the rotational degree of freedom of trapped diatomic molecular ions to the rotational ground state. The molecule of interested, AlH+, is co-trapped and sympathetically cooled with Ba+ to milliKelvin temperatures in its translational degree of freedom. The nearly diagonal Franck-Condon-Factors between the electronic X and A states of AlH+ create semi-closed cycling transitions between the vibrational ground states of X and A states. A spectrally filtered femtosecond laser is used to optically pump the population to the two lowest rotational levels, with opposite parities, in as fast as 100 μs via driving the A-X transition. In addition, a cooling scheme relying on vibrational relaxation brings the population to the N = 0 positive-parity level in as fast as 100 ms. The population distribution among the rotational levels is detected by resonance-enhanced multiphoton dissociation (REMPD) and time-of-flight mass-spectrometry (TOFMS). Although the current two-photon state readout scheme is destructive, a scheme of single-molecule fluorescence detection is also considered.
Shaken not stirred: creating exotic angular momentum states by shaking an optical lattice
NASA Astrophysics Data System (ADS)
Kiely, Anthony; Benseny, Albert; Busch, Thomas; Ruschhaupt, Andreas
We propose a method to create higher orbital states of ultracold atoms in the Mott regime of an optical lattice. This is done by periodically modulating the position of the trap minima (known as shaking) and controlling the interference term of the lasers creating the lattice. These methods are combined with techniques of shortcuts to adiabaticity. As an example of this, we show specifically how to create an anti-ferromagnetic type ordering of angular momentum states of atoms. The specific pulse sequences are designed using Lewis-Riesenfeld invariants and a four-level model for each well. The results are compared with numerical simulations of the full Schrödinger equation.
Resonant state expansion applied to two-dimensional open optical systems
NASA Astrophysics Data System (ADS)
Doost, M. B.; Langbein, W.; Muljarov, E. A.
The resonant state expansion (RSE), a rigorous perturbative method in electrodynamics, is applied to two-dimensional open optical systems. The analytically solvable homogeneous dielectric cylinder is used as an unperturbed system, and its Green's function is shown to contain a cut in the complex frequency plane, which is included in the RSE basis. The complex eigenfrequencies of modes are calculated using the RSE for a selection of perturbations which mix unperturbed modes of different orbital momentum, such as half-cylinder, thin-film, and thin-wire perturbation, demonstrating the accuracy and convergency of the method. The resonant states for the thin-wire perturbation are shown to reproduce an approximative analytical solution.
Dicke superradiance as nondestructive probe for the state of atoms in optical lattices
NASA Astrophysics Data System (ADS)
Brinke, Nicolai ten; Schützhold, Ralf
We present a proposal for a probing scheme utilizing Dicke superradiance to obtain information about ultracold atoms in optical lattices. A probe photon is absorbed collectively by an ensemble of lattice atoms generating a Dicke state. The lattice dynamics (e.g., tunneling) affects the coherence properties of that Dicke state and thus alters the superradiant emission characteristics - which in turn provides insight into the lattice (dynamics). Comparing the Bose-Hubbard and the Fermi-Hubbard model, we find similar superradiance in the strongly interacting Mott insulator regime, but crucial differences in the weakly interacting (superfluid or metallic) phase. Furthermore, we study the possibility to detect whether a quantum phase transition between the two regimes can be considered adiabatic or a quantum quench.
Multidimensional optical spectroscopy of a single molecule in a current-carrying state
Rahav, S.; Mukamel, S.
The nonlinear optical signals from an open system consisting of a molecule connected to metallic leads, in response to a sequence of impulsive pulses, are calculated using a superoperator formalism. Two detection schemes are considered: coherent stimulated emission and incoherent fluorescence. The two provide similar but not identical information. The necessary superoperator correlation functions are evaluated either by converting them to ordinary (Hilbert space) operators which are then expanded in many-body states, or by using Wick's theorem for superoperators to factorize them into nonequilibrium two point Green's functions. As an example we discuss a stimulated Raman process that shows resonances involving two different charge states of the molecule in the same signal. PMID:21197975
Optical imaging of resting-state functional connectivity in a novel arterial stiffness model.
Guevara, Edgar; Sadekova, Nataliya; Girouard, Hélène; Lesage, Frédéric
This study aims to assess the impact of unilateral increases in carotid stiffness on cortical functional connectivity measures in the resting state. Using a novel animal model of induced arterial stiffness combined with optical intrinsic signals and laser speckle imaging, resting state functional networks derived from hemodynamic signals are investigated for their modulation by isolated changes in stiffness of the right common carotid artery. By means of seed-based analysis, results showed a decreasing trend of homologous correlation in the motor and cingulate cortices. Furthermore, a graph analysis indicated a randomization of the cortex functional networks, suggesting a loss of connectivity, more specifically in the motor cortex lateral to the treated carotid, which however did not translate in differentiated metabolic activity.
Optical control and spectroscopic studies of collisional population transfer in molecular electronic states
NASA Astrophysics Data System (ADS)
Ahmed, Ergin; Pan, Xinhua; Huennekens, John; Lyyra, Marjatta
Understanding the basic physics of collision processes between atoms and molecules is of fundamental importance for large number of areas of research including chemical reactivity, ultra cold atoms and molecules, and astrophysics of the interstellar medium. We have experimentally demonstrated optical control of the singlet/triplet probability distribution in the outcome of collisions involving lithium dimer molecules and argon atoms. The control is achieved using the Autler-Townes (AT) effect to manipulate the spin character of a spin-orbit coupled pair of levels serving as a ``gateway'' between the singlet and triplet electronic state manifolds. As a result we show that the rate coefficient of a collisional process between excited molecules (7Li2) and atoms (Ar) leading to internal quantum state changes in the molecules can be effectively manipulated with a laser. In addition, as an extension of these results new gateway levels can be created from singlet and triplet levels that hardly interact to begin with.
Optical Sensing of Polarization States Changes in Meat due to the Ageing
NASA Astrophysics Data System (ADS)
Tománek, Pavel; Mikláš, Jan; Abubaker, Hamed Mohamed; Grmela, Lubomír
Food materials or biological materials display large compositional variations, inhomogeneities, and anisotropic structures. The biological tissues consist of cells which dimensions are bigger than a wavelength of visible light, therefore Mie scattering of transmitted and reflected light occurs and different polarization states arise. The meat industry needs reliable meat quality information throughout the production process in order to guarantee high-quality meat products for consumers. The minor importance is still given to the food quality control and inspection during processing operations or storing conditions. The paper presents a quite simple optical method allowing measure the freshness or ageing of products. The principle is to study temporal characteristics of polarization states of forward or backward scattered laser light in the samples in function of meat ageing.
The optical Tamm states at the interface between a photonic crystal and nanoporous silver
NASA Astrophysics Data System (ADS)
Bikbaev, R. G.; Vetrov, S. Ya; Timofeev, I. V.
The optical Tamm states (OTSs) localized at the edges of a photonic crystal bounded by a nanoporous silver (NPS) film are investigated. NPS involves spherical vacuum nanopores dispersed in the metal matrix and is characterized by the effective resonance permittivity. The transmission, reflection, and absorption spectra of the structures under study at the normal incidence of light are calculated. It is shown that each Tamm state has its own frequency range where the real part of effective permittivity is negative. The light field localization at the high- and low-frequency OTSs is investigated. The specific features of spectral manifestation of the OTSs are studied in dependence on the nanopore concentration in the metal matrix and on the NPS film thickness.
Chemically robust platform for optical solid-state conducting polymer sensor
NASA Astrophysics Data System (ADS)
Holt, A. L.; Bearinger, J. P.; Carter, S. A.
Conjugated polymers are unique materials for use in the development of chemical and biological sensors because of their widely tunable optical and electrical properties that allow them dual functionality as both the sensing element and the signal transducer. Furthermore, as optical photoluminescence based sensors, electroactive polymers are found to exhibit high sensitivity due to the ability of the analyte of interest to quench the photoluminescence of the entire polymer chain. In order to produce a more chemically robust thin film for use as a "solid-state" optical sensor, we succeeded in grafting various poly (3-alkyl-thiophene)s to optically transparent substrates such as glass, quartz, and ITO coated glass. This was accomplished by first grafting a thiophene monomer to the surface then chemically growing the films via oxidative polymerization. XPS studies indicated that each chemical step was accurately understood. The polythiophene growth, unaltered by sonication and tape peeling tests, was uniform across the substrate and could be directed by selective silanization of the substrate. Film thicknesses range from 20 to 200 nm and exhibit varying degrees of surface roughness, depending on the polymerization process. The reaction times and solvents were varied in order to optimize the desired film properties. The absorption and photoluminescence properties of the thin films compared well with literature on spun-cast polythiophene films, as did the electrical conductivities of the doped and undoped material. The photoluminescence intensities of the films are found to be unaffected by paraquat in water but are sensitive to trace amounts of ferric chloride in acetonitrile with measurable Stern Volmer constants.
Model analysis of influences of aerosol mixing state upon its optical properties in East Asia
NASA Astrophysics Data System (ADS)
Han, Xiao; Zhang, Meigen; Zhu, Lingyun; Xu, Liren
The air quality model system RAMS (Regional Atmospheric Modeling System)-CMAQ (Models-3 Community Multi-scale Air Quality) coupled with an aerosol optical/radiative module was applied to investigate the impact of different aerosol mixing states (i.e., externally mixed, half externally and half internally mixed, and internally mixed) on radiative forcing in East Asia. The simulation results show that the aerosol optical depth (AOD) generally increased when the aerosol mixing state changed from externally mixed to internally mixed, while the single scattering albedo (SSA) decreased. Therefore, the scattering and absorption properties of aerosols can be significantly affected by the change of aerosol mixing states. Comparison of simulated and observed SSAs at five AERONET (Aerosol Robotic Network) sites suggests that SSA could be better estimated by considering aerosol particles to be internally mixed. Model analysis indicates that the impact of aerosol mixing state upon aerosol direct radiative forcing (DRF) is complex. Generally, the cooling effect of aerosols over East Asia are enhanced in the northern part of East Asia (Northern China, Korean peninsula, and the surrounding area of Japan) and are reduced in the southern part of East Asia (Sichuan Basin and Southeast China) by internal mixing process, and the variation range can reach ±5 W m-2. The analysis shows that the internal mixing between inorganic salt and dust is likely the main reason that the cooling effect strengthens. Conversely, the internal mixture of anthropogenic aerosols, including sulfate, nitrate, ammonium, black carbon, and organic carbon, could obviously weaken the cooling effect.
Evaluation of optical and chromatic properties under electrical and thermal coupling in solid state lighting systems
NASA Astrophysics Data System (ADS)
Fu, Han-Kuei; Peng, Yi-Ping; Wang, Chien-Ping; Chiang, Hsin-Chien; Chen, Tzung-Te; Chen, Chiu-Ling; Chou, Pei-Ting
For energy-saving, high efficiency and low pollution, the lighting of LED systems is important for the future of green energy technology industry. The solid state lighting becomes the replacement of traditional lighting, such as, light bulbs and compact fluorescent lamps. Because of the semiconductor characteristics, the luminous efficiency of LEDs is sensitive to the operating temperature. Besides increasing the luminous efficiency, effective controlling electricity and thermal characteristics in the design of LED lighting products is the key point to achieve the best results. LED modules can be combined with multi-grain process or through a combination of multiple LED chips. Accurate analysis of this LED module for the electrical, thermal characteristics and high reliability is the critical knowledge of modular design. In this report, we studied the electrical and thermal coupling phenomenon in solid state lighting systems to analyze their reliability. By experiments and simulations, we obtained the apparent variation of temperature distribution of LED system due to differences of their forward voltages and thermal resistances. These events may reduce their reliability. Besides, the evaluation of optical and chromatic properties was based on the variation of temperature distribution and current of LED system. This is the key technology to predict the optical and chromatic properties of LED system in use.
Optical techniques for determination of the state of cure of epoxy resin based systems
NASA Astrophysics Data System (ADS)
Michie, W. C.; Thursby, G.; Johnstone, W.; Culshaw, B.
Determination of the state of cure of epoxy resin based systems is of considerable interest to manufacturers of large carbon fiber reinforced plastic and glass reinforced plastic structures. Optical methods designed to indicate the cure state have been developed using a loss mechanism which is a function of the refractive index of the curing system. Such techniques are however subject to corruption from losses arising from other influences and consequently are limited in their measurement resolution. In this paper, two techniques which are able to provide a high degree of accuracy of measurement of refractive index are investigated as a means of performing cure measurements. The methods investigated involve the interaction of the evanescent field of a side polished optical fiber with an overlay waveguide or a surface plasmon. Coupling between the fiber and the overlay waveguide (or plasmon) is strongly influenced by the refractive index of the bulk superstrate above the overlay (in this case the curing resin system). Both sensing schemes are self referencing and are not influenced by loss.
Damage resistant optics for a mega-joule solid-state laser
NASA Astrophysics Data System (ADS)
Campbell, J. H.; Rainer, F.; Kozlowski, M. R.; Wolfe, C. R.; Thomas, I.; Milanovich, F.
Research on Inertial Confinement Fusion (ICF) has progressed rapidly in the past several years. As a consequence, LLNL is developing plans to upgrade the current 120 kJ solid state (Nd3+ phosphate glass) Nova laser to a 1.5 to 2 megajoule system with the goal of achieving fusion ignition. The design of the planned Nova Upgrade is briefly discussed. Because of recent improvements in the damage resistance of optical materials it is now technically and economically feasible to build a megajoule-class solid state laser. Specifically, the damage threshold of Nd(+3)-doped phosphate laser glass, multilayer dielectric coatings, and non-linear optical crystals (e.g., KDP) have been dramatically improved. These materials now meet the fluence requirements for a 1.5 to 2 MJ Nd(+3)-glass laser operating at 1054 and 351 nm and at a pulse length of 3 ns. The recent improvements in damage thresholds are reviewed; threshold data at both 1064 and 355 nm and the measured pulse length scaling are presented.
Mercury in fish tissue of Idaho lakes vs. those of the Northeastern United States as it relates to the moderating effects of selenium
The primary methyl-mercury (MeHg) exposure mode to wildlife and humans is through the consumption of aquatic organisms, particulary fish. Selenium has been demonstrated to moderate the toxicity of MeHg in every test animal type examined to date. A molar ratio of Se:Hg >1 appear...
Optical cryo-imaging of kidney mitochondrial redox state in diabetic mice models
NASA Astrophysics Data System (ADS)
Maleki, S.; Sepehr, R.; Staniszewski, K.; Sheibani, N.; Sorenson, C. M.; Ranji, M.
Oxidative stress (OS), which increases during diabetes, exacerbates the development and progression of diabetes complications including renal vascular and proximal tubule cell dysfunction. The objective of this study was to investigate the changes in the metabolic state of the tissue in diabetic mice kidneys using fluorescence imaging. Mitochondrial metabolic coenzymes NADH (Nicotinamide Adenine Dinucleotide), and FADH-2 (Flavin Adenine Dinucleotide) are autofluorescent and can be monitored without exogenous labels by optical techniques. The ratio of the fluorescence intensity of these fluorophores, (NADH/FAD), called the NADH redox ratio (RR), is a marker of metabolic state of a tissue. We examined mitochondrial redox states of kidneys from diabetic mice, Akita/+ and its control wild type (WT) for a group of 8- and 12-week-old mice. Average intensity and histogram of maximum projected images of FAD, NADH, and NADH RR were calculated for each kidney. Our results indicated a 17% decrease in the mean NADH RR of the kidney from 8-week-old mice compared with WT mice and, a 30% decrease in the mean NADH RR of kidney from12-week-old mice compared with WT mice. These results indicated an increase in OS in diabetic animals and its progression over time. Thus, NADH RR can be used as a hallmark of OS in diabetic kidney allowing temporal identification of oxidative state.
Structure of multiphoton quantum optics. I. Canonical formalism and homodyne squeezed states
NASA Astrophysics Data System (ADS)
dell'Anno, Fabio; de Siena, Silvio; Illuminati, Fabrizio
We introduce a formalism of nonlinear canonical transformations for general systems of multiphoton quantum optics. For single-mode systems the transformations depend on a tunable free parameter, the homodyne local-oscillator angle; for n -mode systems they depend on n heterodyne mixing angles. The canonical formalism realizes nontrivial mixing of pairs of conjugate quadratures of the electromagnetic field in terms of homodyne variables for single-mode systems, and in terms of heterodyne variables for multimode systems. In the first instance the transformations yield nonquadratic model Hamiltonians of degenerate multiphoton processes and define a class of non-Gaussian, nonclassical multiphoton states that exhibit properties of coherence and squeezing. We show that such homodyne multiphoton squeezed states are generated by unitary operators with a nonlinear time evolution that realizes the homodyne mixing of a pair of conjugate quadratures. Tuning of the local-oscillator angle allows us to vary at will the statistical properties of such states. We discuss the relevance of the formalism for the study of degenerate (up-)down-conversion processes. In a companion paper [
Symmetry of electron states and optical transitions in GaN/AlN hexagonal quantum dots
NASA Astrophysics Data System (ADS)
Tronc, P.; Smirnov, V. P.; Zhuravlev, K. S.
The exact symmetry of hexagonal quantum dots (QDs) made of materials with the wurtzite structure such as GaN/AlN QDs for example, is described by the C3v point group and does not depend on the existence of a wetting layer. We have determined the possible exact symmetries of electron states and vibration modes in the dots and derived the optical selection rules. The vibration modes involved in the Frölich interaction are totally symmetric with respect to the C3v group and can induce transitions only between states with the same symmetry. The not totally symmetric modes provide other channels for lowering the energy of excited carriers and excitons by connecting states with symmetries different one from another. The rapid decay of created polarons, due to the short lifetime of vibration modes, releases the carriers and excitons into ground levels. In the envelope function approximation (EFA), the symmetry of the dots is represented by the C6v point group. Interband transitions are allowed only between states whose envelope functions have the same symmetry. EFA artificially increases the number of dark exciton symmetries.
Optical communication with two-photon coherent states. II - Photoemissive detection and structured receiver performance
NASA Technical Reports Server (NTRS)
Shapiro, J. H.; Yuen, H. P.; Machado Mata, J. A.
In a previous paper (1978), the authors developed a method of analyzing the performance of two-photon coherent state (TCS) systems for free-space optical communications. General theorems permitting application of classical point process results to detection and estimation of signals in arbitrary quantum states were derived. The present paper examines the general problem of photoemissive detection statistics. On the basis of the photocounting theory of Kelley and Kleiner (1964) it is shown that for arbitrary pure state illumination, the resulting photocurrent is in general a self-exciting point process. The photocount statistics for first-order coherent fields reduce to those of a special class of Markov birth processes, which the authors term single-mode birth processes. These general results are applied to the structure of TCS radiation, and it is shown that the use of TCS radiation with direct or heterodyne detection results in minimal performance increments over comparable coherent-state systems. However, significant performance advantages are offered by use of TCS radiation with homodyne detection. The abstract quantum descriptions of homodyne and heterodyne detection are derived and a synthesis procedure for obtaining quantum measurements described by arbitrary TCS is given.
Structure of multiphoton quantum optics. I. Canonical formalism and homodyne squeezed states
Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio
We introduce a formalism of nonlinear canonical transformations for general systems of multiphoton quantum optics. For single-mode systems the transformations depend on a tunable free parameter, the homodyne local-oscillator angle; for n-mode systems they depend on n heterodyne mixing angles. The canonical formalism realizes nontrivial mixing of pairs of conjugate quadratures of the electromagnetic field in terms of homodyne variables for single-mode systems, and in terms of heterodyne variables for multimode systems. In the first instance the transformations yield nonquadratic model Hamiltonians of degenerate multiphoton processes and define a class of non-Gaussian, nonclassical multiphoton states that exhibit properties of coherence and squeezing. We show that such homodyne multiphoton squeezed states are generated by unitary operators with a nonlinear time evolution that realizes the homodyne mixing of a pair of conjugate quadratures. Tuning of the local-oscillator angle allows us to vary at will the statistical properties of such states. We discuss the relevance of the formalism for the study of degenerate (up-)down-conversion processes. In a companion paper [F. Dell'Anno, S. De Siena, and F. Illuminati, 69, 033813 (2004)], we provide the extension of the nonlinear canonical formalism to multimode systems, we introduce the associated heterodyne multiphoton squeezed states, and we discuss their possible experimental realization.
Morphology and mixing state of atmospheric particles: Links to optical properties and cloud processing
NASA Astrophysics Data System (ADS)
China, Swarup
Atmospheric particles are ubiquitous in Earth's atmosphere and impact the environment and the climate while affecting human health and Earth's radiation balance, and degrading visibility. Atmospheric particles directly affect our planet's radiation budget by scattering and absorbing solar radiation, and indirectly by interacting with clouds. Single particle morphology (shape, size and internal structure) and mixing state (coating by organic and inorganic material) can significantly influence the particle optical properties as well as various microphysical processes, involving cloud-particle interactions and including heterogeneous ice nucleation and water uptake. Conversely, aerosol cloud processing can affect the morphology and mixing of the particles. For example, fresh soot has typically an open fractal-like structure, but aging and cloud processing can restructure soot into more compacted shapes, with different optical and ice nucleation properties. During my graduate research, I used an array of electron microscopy and image analysis tools to study morphology and mixing state of a large number of individual particles collected during several field and laboratory studies. To this end, I investigated various types of particles such as tar balls (spherical carbonaceous particles emitted during biomass burning) and dust particles, but with a special emphasis on soot particles. In addition, I used the Stony Brook ice nucleation cell facility to investigate heterogeneous ice nucleation and water uptake by long-range transported particles collected at the Pico Mountain Observatory, in the Archipelago of the Azores. Finally, I used ice nucleation data from the SAAS (Soot Aerosol Aging Study) chamber study at the Pacific Northwest National Laboratory to understand the effects that ice nucleation and supercooled water processing has on the morphology of residual soot particles. Some highlights of our findings and implications are discussed next. We found that the
Optical communication with two-photon coherent stages. I - Quantum-state propagation and quantum-noise reduction
NASA Technical Reports Server (NTRS)
Yuen, H. P.; Shapiro, J. H.
To determine the ultimate performance limitations imposed by quantum effects, it is also essential to consider optimum quantum-state generation. Certain 'generalized' coherent states of the radiation field possess novel quantum noise characteristics that offer the potential for greatly improved optical communications. These states have been called two-photon coherent states because they can be generated, in principle, by stimulated two-photon processes. The use of two-photon coherent state (TCS) radiation in free-space optical communications is considered. A simple theory of quantum state propagation is developed. The theory provides the basis for representing the free-space channel in a quantum-mechanical form convenient for communication analysis. The new theory is applied to TCS radiation.
Continuous-variable quantum cloning of coherent states with phase-conjugate input modes using linear optics
Chen, Haixia; Zhang, Jing
We propose a scheme for continuous-variable quantum cloning of coherent states with phase-conjugate input modes using linear optics. The quantum cloning machine yields M identical optimal clones from N replicas of a coherent state and N replicas of its phase conjugate. This scheme can be straightforwardly implemented with the setups accessible at present since its optical implementation only employs simple linear optical elements and homodyne detection. Compared with the original scheme for continuous-variable quantum cloning with phase-conjugate input modes proposed by Cerf and Iblisdir [Phys. Rev. Lett. 87, 247903 (2001)], which utilized a nondegenerate optical parametric amplifier, our scheme loses the output of phase-conjugate clones and is regarded as irreversible quantum cloning.
Fully stabilized optical frequency comb with sub-radian CEO phase noise from a SESAM-modelocked 1.5-µm solid-state laser.
Schilt, Stephane; Bucalovic, Nikola; Dolgovskiy, Vladimir; Schori, Christian; Stumpf, Max C; Di Domenico, Gianni; Pekarek, Selina; Oehler, Andreas E H; Südmeyer, Thomas; Keller, Ursula; Thomann, Pierre
We report the first full stabilization of an optical frequency comb generated from a femtosecond diode-pumped solid-state laser (DPSSL) operating in the 1.5-μm spectral region. The stability of the comb is characterized in free-running and in phase-locked operation by measuring the noise properties of the carrier-envelope offset (CEO) beat, of the repetition rate, and of a comb line at 1558 nm. The high Q-factor of the semiconductor saturable absorber mirror (SESAM)-modelocked 1.5-µm DPSSL results in a low-noise CEO-beat, for which a tight phase lock can be much more easily realized than for a fiber comb. Using a moderate feedback bandwidth of only 5.5 kHz, we achieved a residual integrated phase noise of 0.72 rad rms for the locked CEO, which is one of the smallest values reported for a frequency comb system operating in this spectral region. The fractional frequency stability of the CEO-beat is 20‑fold better than measured in a standard self-referenced commercial fiber comb system and contributes only 10(-15) to the optical carrier frequency instability at 1 s averaging time.
Optical Flow and Driver's Kinematics Analysis for State of Alert Sensing
Jiménez-Pinto, Javier; Torres-Torriti, Miguel
Road accident statistics from different countries show that a significant number of accidents occur due to driver's fatigue and lack of awareness to traffic conditions. In particular, about 60% of the accidents in which long haul truck and bus drivers are involved are attributed to drowsiness and fatigue. It is thus fundamental to improve non-invasive systems for sensing a driver's state of alert. One of the main challenges to correctly resolve the state of alert is measuring the percentage of eyelid closure over time (PERCLOS), despite the driver's head and body movements. In this paper, we propose a technique that involves optical flow and driver's kinematics analysis to improve the robustness of the driver's alert state measurement under pose changes using a single camera with near-infrared illumination. The proposed approach infers and keeps track of the driver's pose in 3D space in order to ensure that eyes can be located correctly, even after periods of partial occlusion, for example, when the driver stares away from the camera. Our experiments show the effectiveness of the approach with a correct eyes detection rate of 99.41%, on average. The results obtained with the proposed approach in an experiment involving fifteen persons under different levels of sleep deprivation also confirm the discriminability of the fatigue levels. In addition to the measurement of fatigue and drowsiness, the pose tracking capability of the proposed approach has potential applications in distraction assessment and alerting of machine operators. PMID:23539029
Optical imaging of mitochondrial redox state in rodent model of retinitis pigmentosa
NASA Astrophysics Data System (ADS)
Maleki, Sepideh; Gopalakrishnan, Sandeep; Ghanian, Zahra; Sepehr, Reyhaneh; Schmitt, Heather; Eells, Janis; Ranji, Mahsa
Oxidative stress (OS) and mitochondrial dysfunction contribute to photoreceptor cell loss in retinal degenerative disorders. The metabolic state of the retina in a rodent model of retinitis pigmentosa (RP) was investigated using a cryo-fluorescence imaging technique. The mitochondrial metabolic coenzymes nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) are autofluorescent and can be monitored without exogenous labels using optical techniques. The cryo-fluorescence redox imaging technique provides a quantitative assessment of the metabolism. More specifically, the ratio of the fluorescence intensity of these fluorophores (NADH/FAD), the NADH redox ratio (RR), is a marker of the metabolic state of the tissue. The NADH RR and retinal function were examined in an established rodent model of RP, the P23H rat compared to that of nondystrophic Sprague-Dawley (SD) rats. The NADH RR mean values were 1.11±0.03 in the SD normal and 0.841±0.01 in the P23H retina, indicating increased OS in the P23H retina. Electroretinographic data revealed a significant reduction in photoreceptor function in P23H animals compared to SD nozrmal rats. Thus, cryo-fluorescence redox imaging was used as a quantitative marker of OS in eyes from transgenic rats and demonstrated that alterations in the oxidative state of eyes occur during the early stages of RP.
Optical flow and driver's kinematics analysis for state of alert sensing.
Jiménez-Pinto, Javier; Torres-Torriti, Miguel
Road accident statistics from different countries show that a significant number of accidents occur due to driver's fatigue and lack of awareness to traffic conditions. In particular, about 60% of the accidents in which long haul truck and bus drivers are involved are attributed to drowsiness and fatigue. It is thus fundamental to improve non-invasive systems for sensing a driver's state of alert. One of the main challenges to correctly resolve the state of alert is measuring the percentage of eyelid closure over time (PERCLOS), despite the driver's head and body movements. In this paper, we propose a technique that involves optical flow and driver's kinematics analysis to improve the robustness of the driver's alert state measurement under pose changes using a single camera with near-infrared illumination. The proposed approach infers and keeps track of the driver's pose in 3D space in order to ensure that eyes can be located correctly, even after periods of partial occlusion, for example, when the driver stares away from the camera. Our experiments show the effectiveness of the approach with a correct eyes detection rate of 99.41%, on average. The results obtained with the proposed approach in an experiment involving fifteen persons under different levels of sleep deprivation also confirm the discriminability of the fatigue levels. In addition to the measurement of fatigue and drowsiness, the pose tracking capability of the proposed approach has potential applications in distraction assessment and alerting of machine operators.
Determining the equation of state of amorphous solids at high pressure using optical microscopy.
Amin, Samrat A; Rissi, Erin N; McKiernan, Keri; Yarger, Jeffery L
A method to determine the volumetric equation of state of amorphous solids using optical microscopy in a diamond anvil cell is described. The method relies on two- dimensional image acquisition and analysis to quantify changes in the projected image area with compression. The area analysis methods prove to be robust against improper focusing and lighting conditions while providing the accuracy necessary to deduce small area changes, which correspond to small volume changes in an isotropic material. The image capture, area analysis method is used to determine the compression of cubic crystals, yielding results in good agreement with diffraction and volumetric measurements. As a proof of concept, the equation of state of amorphous red phosphorus is measured up to 12 GPa under hydrostatic conditions where the quantified volume change between the red and black phases is approximately ΔV/V(0) ≈ 0.05 after a reduction of volume nearing 35% at 8 GPa. A large hysteresis is present during decompression and eventually results in a 15% permanent densification relative to the starting volume, which is attributed to a pressure induced crystallization from red to black phosphorus. The robustness of the technique is also demonstrated by measuring the equation of state of GeSe(2) glasses for semi transparent samples and As(2)O(3) in which gold coating is used as a contrasting aid.
Density of states, optical and thermoelectric properties of perovskite vanadium fluorides Na3VF6
NASA Astrophysics Data System (ADS)
Reshak, A. H.; Azam, Sikander
The electronic structure, charge density and Fermi surface of Na3VF6 compound have been examined with the support of density functional theory (DFT). Using the full potential linear augmented plane wave method, we employed the local density approximation (LDA), generalized gradient approximation (GGA) and Engel-Vosko GGA (EVGGA) to treat the exchange correlation potential to solve Kohn-Sham equations. The calculation show that Na3VF6 compound has metallic nature and the Fermi energy (EF) is assessed by overlapping of V-d state. The calculated density of states at the EF are about 18.655, 51.932 and 13.235 states/eV, and the bare linear low-temperature electronic specific heat coefficient (γ) is found to be 3.236 mJ/mol-K2, 9.008 mJ/mol-K2 and 2.295 mJ/mol-K2 for LDA, GGA and EVGGA, respectively. The Fermi surface is composed of two sheets. The chemical bonding of Na3VF6 compound is analyzed through the electronic charge density in the (1 1 0) crystallographic plane. The optical constants and thermal properties were also calculated and discussed.
Single-photon-level optical storage in a solid-state spin-wave memory
NASA Astrophysics Data System (ADS)
Timoney, N.; Usmani, I.; Jobez, P.; Afzelius, M.; Gisin, N.
A long-lived quantum memory is a firm requirement for implementing a quantum repeater scheme. Recent progress in solid-state rare-earth-ion-doped systems justifies their status as very strong candidates for such systems. Nonetheless an optical memory based on spin-wave storage at the single-photon level has not been shown in such a system to date, which is crucial for achieving the long storage times required for quantum repeaters. In this paper we show that it is possible to execute a complete atomic frequency comb (AFC) scheme, including spin-wave storage, with weak coherent pulses of n¯=2.5±0.6 photons per pulse. We discuss in detail the experimental steps required to obtain this result and demonstrate the coherence of a stored time-bin pulse. We show a noise level of (7.1±2.3)×10-3 photons per mode during storage, and this relatively low noise level paves the way for future quantum optics experiments using spin waves in rare-earth-doped crystals.
Solid-state luminescence for the optical examination of archaeological glass beads
NASA Astrophysics Data System (ADS)
Zacharias, N.; Beltsios, K.; Oikonomou, A.; Karydas, A. G.; Bassiakos, Y.; Michael, C. T.; Zarkadas, Ch.
The work pertains to the application of solid-state luminescence as a characterization tool for glassy ceramic cultural artefacts. An archaeological glass bead collection excavated at the city of Thebes, Greece and considered as unique in terms of typological variety and time span was examined with the application of luminescence techniques (thermoluminescence, optically stimulated luminescence). Additionally, X-rays fluorescence (XRF) was used to provide non-destructively the elemental concentration profile of the samples. The thermoluminescence signals following laboratory irradiation provided distinct groups of spectra types according to the color classification of the samples. For each sample, the signal sensitivity and growth were examined using both thermoluminescence and optically stimulated luminescence recording. The study provides evidence for the usefulness of the combined application of luminescence and non-destructive, XRF-based, elemental analysis for the characterization of glass assemblages. Finally, due to the satisfactory level of radiation-induced signal intensity, the work suggests the possibility of chronological estimation of ancient glass beads using luminescence dating protocols.
Multiscale dispersion-state characterization of nanocomposites using optical coherence tomography
NASA Astrophysics Data System (ADS)
Schneider, Simon; Eppler, Florian; Weber, Marco; Olowojoba, Ganiu; Weiss, Patrick; Hübner, Christof; Mikonsaari, Irma; Freude, Wolfgang; Koos, Christian
Nanocomposite materials represent a success story of nanotechnology. However, development of nanomaterial fabrication still suffers from the lack of adequate analysis tools. In particular, achieving and maintaining well-dispersed particle distributions is a key challenge, both in material development and industrial production. Conventional methods like optical or electron microscopy need laborious, costly sample preparation and do not permit fast extraction of nanoscale structural information from statistically relevant sample volumes. Here we show that optical coherence tomography (OCT) represents a versatile tool for nanomaterial characterization, both in a laboratory and in a production environment. The technique does not require sample preparation and is applicable to a wide range of solid and liquid material systems. Large particle agglomerates can be directly found by OCT imaging, whereas dispersed nanoparticles are detected by model-based analysis of depth-dependent backscattering. Using a model system of polystyrene nanoparticles, we demonstrate nanoparticle sizing with high accuracy. We further prove the viability of the approach by characterizing highly relevant material systems based on nanoclays or carbon nanotubes. The technique is perfectly suited for in-line metrology in a production environment, which is demonstrated using a state-of-the-art compounding extruder. These experiments represent the first demonstration of multiscale nanomaterial characterization using OCT.
Multiscale dispersion-state characterization of nanocomposites using optical coherence tomography
Schneider, Simon; Eppler, Florian; Weber, Marco; Olowojoba, Ganiu; Weiss, Patrick; Hübner, Christof; Mikonsaari, Irma; Freude, Wolfgang; Koos, Christian
Nanocomposite materials represent a success story of nanotechnology. However, development of nanomaterial fabrication still suffers from the lack of adequate analysis tools. In particular, achieving and maintaining well-dispersed particle distributions is a key challenge, both in material development and industrial production. Conventional methods like optical or electron microscopy need laborious, costly sample preparation and do not permit fast extraction of nanoscale structural information from statistically relevant sample volumes. Here we show that optical coherence tomography (OCT) represents a versatile tool for nanomaterial characterization, both in a laboratory and in a production environment. The technique does not require sample preparation and is applicable to a wide range of solid and liquid material systems. Large particle agglomerates can be directly found by OCT imaging, whereas dispersed nanoparticles are detected by model-based analysis of depth-dependent backscattering. Using a model system of polystyrene nanoparticles, we demonstrate nanoparticle sizing with high accuracy. We further prove the viability of the approach by characterizing highly relevant material systems based on nanoclays or carbon nanotubes. The technique is perfectly suited for in-line metrology in a production environment, which is demonstrated using a state-of-the-art compounding extruder. These experiments represent the first demonstration of multiscale nanomaterial characterization using OCT. PMID:27557544
Resting-state functional connectivity in the human brain revealed with diffuse optical tomography
White, Brian R.; Snyder, Abraham Z.; Cohen, Alexander L.; Petersen, Steven E.; Raich-le, Marcus E.; Schlaggar, Bradley L.; Culver, Joseph P.
Mapping resting-state networks allows insight into the brain's functional architecture and physiology and has rapidly become important in contemporary neuroscience research. Diffuse optical tomography (DOT) is an emerging functional neuroimaging technique with the advantages, relative to functional magnetic resonance imaging (fMRI), of portability and the ability to simultaneously measure both oxy- and deoxy-hemoglobin. Previous optical studies have evaluated the temporal features of spontaneous resting brain signals. Herein, we develop techniques for spatially mapping functional connectivity with DOT (fc-DOT). Simultaneous imaging over the motor and visual cortices yielded robust correlation maps reproducing the expected functional neural architecture. The localization of the maps was confirmed with task-response studies and with subject-matched fc-MRI. These fc-DOT methods provide a task-less approach to mapping brain function in populations that were previously difficult to research. Our advances may permit new studies of early childhood development and of unconscious patients. In addition, the comprehensive hemoglobin contrasts of fc-DOT enable innovative studies of the biophysical origin of the functional connectivity signal. PMID:19344773
Dynamic translocation of ligand-complexed DNA through solid-state nanopores with optical tweezers
NASA Astrophysics Data System (ADS)
Sischka, Andy; Spiering, Andre; Khaksar, Maryam; Laxa, Miriam; König, Janine; Dietz, Karl-Josef; Anselmetti, Dario
We investigated the threading and controlled translocation of individual lambda-DNA (λ-DNA) molecules through solid-state nanopores with piconewton force sensitivity, millisecond time resolution and picoampere ionic current sensitivity with a set-up combining quantitative 3D optical tweezers (OT) with electrophysiology. With our virtually interference-free OT set-up the binding of RecA and single peroxiredoxin protein molecules to λ-DNA was quantitatively investigated during dynamic translocation experiments where effective forces and respective ionic currents of the threaded DNA molecule through the nanopore were measured during inward and outward sliding. Membrane voltage-dependent experiments of reversible single protein/DNA translocation scans yield hysteresis-free, asymmetric single-molecule fingerprints in the measured force and conductance signals that can be attributed to the interplay of optical trap and electrostatic nanopore potentials. These experiments allow an exact localization of the bound protein along the DNA strand and open fascinating applications for label-free detection of DNA-binding ligands, where structural and positional binding phenomena can be investigated at a single-molecule level.
Entanglement and the ground state of fermions trapped in optical lattices
NASA Astrophysics Data System (ADS)
Silva-Valencia, J.; Franco, R.; Figueira, M. S.
Using White's density matrix renormalization group technique we calculate entanglement of fermions confined in a one-dimensional trap with an underlying lattice. The system is modeled using a repulsive Hubbard model plus a quadratic potential. Due to the confining potential, metallic and Mott-insulating domains coexist in the system. The entanglement is measured by the on-site entropy and the block entropy, and these quantities are calculated as a function of the local repulsion and the curvature of the trap. We found that local entropy decreases with the curvature for a fixed on-site repulsion. As a function of the on-site repulsion the local entropy first increases and then diminishes. Our most important goal is to show that local and block entropy are useful tools for characterization of the ground states of fermions trapped in optical lattices.
Solid-state semiconductor optical cryocooler based on CdS nanobelts.
Li, Dehui; Zhang, Jun; Wang, Xinjiang; Huang, Baoling; Xiong, Qihua
We demonstrate the laser cooling of silicon-on-insulator (SOI) substrate using CdS nanobelts. The local temperature change of the SOI substrate exactly beneath the CdS nanobelts is deduced from the ratio of the Stokes and anti-Stokes Raman intensities from the Si layer on the top of the SOI substrate. We have achieved a 30 and 20 K net cooling starting from 290 K under a 3.8 mW 514 nm and a 4.4 mW 532 nm pumping, respectively. In contrast, a laser heating effect has been observed pumped by 502 and 488 nm lasers. Theoretical analysis based on the general static heat conduction module in the Ansys program package is conducted, which agrees well with the experimental results. Our investigations demonstrate the laser cooling capability of an external thermal load, suggesting the applications of II-VI semiconductors in all-solid-state optical cryocoolers.
Fluorescence reabsorption calculation and influence on solid-state optical cooling.
Wang, Xiaofeng; Chang, Shengli; Yang, Jiankun; Zhou, Mu; Cao, Dingxiang; Tan, Jichun
The calculation model of fluorescence reabsorption and reemission with consideration of reflection on the boundary and material size using Monte Carlo method is proposed. To validate this stochastic model, experiments were conducted, and the calculated steady state spectra showed a good agreement with measurements. Using the absorption and fluorescence spectra of Yb-doped phosphate glass by careful measurements and corrections, we calculated the redshift in the observed fluorescence spectra and external quantum efficiency caused by fluorescence reabsorption and re-emission for the samples with the geometries of cylinder and cuboid. The calculation results show that the fluorescence reabsorption and re-emission have significant influence on the cooling efficiency. The calculation results also show that the cylinder with small waist beam incident (the incident light beam diameter is much less than the size of the sample, and goes through the center of the sample) is suitable for optical cooling.
Analysis of excited-state Faraday anomalous dispersion optical filter at 1529 nm.
Xiong, Junyu; Yin, Longfei; Luo, Bin; Guo, Hong
In this work, a detailed theoretical analysis of 1529 nm ES-FADOF (excited state Faraday anomalous dispersion optical filter) based on rubidium atoms pumped by 780 nm laser is introduced, where Zeeman splitting, Doppler broadening, and relaxation processes are considered. Experimental results are carefully compared with the derivation. The results prove that the optimal pumping frequency is affected by the working magnetic field. The population distribution among all hyperfine Zeeman sublevels under the optimal pumping frequency has also been obtained, which shows that 85Rb atoms are the main contribution to the population. The peak transmittance above 90% is obtained, which is in accordance with the experiment. The calculation also shows that the asymmetric spectra observed in the experiment are caused by the unbalanced population distribution among Zeeman sublevels. This theoretical model can be used for all kinds of calculations for FADOF.
Self-ordered stationary states of driven quantum degenerate gases in optical resonators
NASA Astrophysics Data System (ADS)
Sandner, R. M.; Niedenzu, W.; Piazza, F.; Ritsch, H.
We study the role of quantum statistics in the self-ordering of ultracold bosons and fermions moving inside an optical resonator with transverse coherent pumping. For few particles we numerically compute the nonequilibrium dynamics of the density matrix towards the self-ordered stationary state of the coupled atom-cavity system. We include quantum fluctuations of the particles and the cavity field. These fluctuations in conjunction with cavity cooling determine the stationary distribution of the particles, which exhibits a transition from a homogeneous to a spatially ordered phase with the appearance of a superradiant scattering peak in the cavity output spectrum. While the ordering threshold is generally lower for bosons, we confirm the recently predicted zero pump strength threshold for superradiant scattering for fermions when the cavity photon momentum coincides with twice the Fermi momentum.
Excited-state dynamics and nonlinear optical response of Ge nanocrystals embedded in silica matrix
NASA Astrophysics Data System (ADS)
Razzari, Luca; Gnoli, Andrea; Righini, Marcofabio; Dâna, Aykutlu; Aydinli, Atilla
We use a dedicated Z-scan setup, arranged to account for cumulative effects, to study the nonlinear optical response of Ge nanocrystals embedded in silica matrix. Samples are prepared with plasma-enchanced chemical-vapor deposition and post-thermal annealing. We measure a third-order nonlinear refraction coefficient of γ =1×10-16m2/W. The nonlinear absorption shows an intensity-independent coefficient of β =4×10-10m/W related to fast processes. In addition, we measure a second β component around 10-9m /W with a relaxation time of 300μs that rises linearly with the laser intensity. We associate its origin to the absorption of excited carriers from a surface-defect state with a long depopulation time.
Optical density of states in ultradilute GaAsN alloy: Coexistence of free excitons and impurity band of localized and delocalized states
Bhuyan, Sumi; Pal, Bipul; Bansal, Bhavtosh; Das, Sanat K.; Dhar, Sunanda
Optically active states in liquid phase epitaxy-grown ultra-dilute GaAsN are studied. The feature-rich low temperature photoluminescence spectrum has contributions from excitonic band states of the GaAsN alloy, and two types of defect states—localized and extended. The degree of delocalization for extended states both within the conduction and defect bands, characterized by the electron temperature, is found to be similar. The degree of localization in the defect band is analyzed by the strength of the phonon replicas. Stronger emission from these localized states is attributed to their giant oscillator strength.
Probing iron spin state by optical absorption in laser-heated diamond anvil cell
NASA Astrophysics Data System (ADS)
Lobanov, S.; Goncharov, A. F.; Holtgrewe, N.; Lin, J. F.
Pressure-induced spin-pairing transitions in iron-bearing minerals have been in the focus of geophysical studies1. Modern consensus is that iron spin state in the lower mantle is a complex function of crystal structure, composition, pressure, and temperature. Discontinuities in physical properties of lower mantle minerals have been revealed over the spin transition pressure range, but at room temperature. In this work, we have used a supercontinuum laser source and an intensified CCD camera to probe optical properties of siderite, FeCO3, and post-perovskite, Mg0.9Fe0.1SiO3, across the spin transition in laser-heated diamond anvil cell. Synchronously gating the CCD with the supercontinuum pulses (Fig. 1A) allowed diminishing thermal background to ~8.3*10-4. Utilizing the experimental setup we infer the spin state of ferrous iron in siderite at high pressure and temperature conditions (Fig. 1B). Similar behavior is observed for low spin ferric iron in post-perovskite at 130 GPa indicating that all iron in post-perovskite is high spin at lower mantle conditions. Also, our experimental setup holds promise for measuring radiative thermal conductivity of mantle minerals at relevant mantle conditions. Figure 1. (A) Timing of the optical absorption measurements at high temperature. (B) High temperature siderite absorption spectra at 45 GPa. Before heating and quenched after 1300 K spectra are shown in light and dark blue, respectively. Green and red curves are absorption spectra at 1200 K and 1300 K, respectively. Spectra shown in black represent room temperature absorption data on HS (43 GPa) and LS (45.5 GPa) siderite after Lobanov et al., 2015, shown for comparison.
Chaotic quantum ratchets and filters with cold atoms in optical lattices: Properties of Floquet states
NASA Astrophysics Data System (ADS)
Hur, Gwang-Ok
The -kicked rotor is a paradigm of quantum chaos. Its realisation with clouds of cold atoms in pulsed optical lattices demonstrated the well-known quantum chaos phenomenon of 'dynamical localisation'. In those experi ments by several groups world-wide, the £-kicks were applied at equal time intervals. However, recent theoretical and experimental work by the cold atom group at UCL Monteiro et al 2002, Jonckheere et al 2003, Jones et al 2004 showed that novel quantum and classical dynamics arises if the atomic cloud is pulsed with repeating sequences of unequally spaced kicks. In Mon teiro et al 2002 it was found that the energy absorption rates depend on the momentum of the atoms relative to the optical lattice hence a type of chaotic ratchet was proposed. In Jonckheere et al and Jones et al, a possible mechanism for selecting atoms according to their momenta (velocity filter) was investigated. The aim of this thesis was to study the properties of the underlying eigen values and eigenstates. Despite the unequally-spaced kicks, these systems are still time-periodic, so we in fact investigated the Floquet states, which are eigenstates of U(T), the one-period time evolution operator. The Floquet states and corresponding eigenvalues were obtained by diagonalising a ma trix representation of the operator U(T). It was found that the form of the eigenstates enables us to analyse qual itatively the atomic momentum probability distributions, N(p) measured experimentally. In particular, the momentum width of the individual eigen states varies strongly with < p > as expected from the theoretical and ex- perimental results obtained previously. In addition, at specific < p > close to values which in the experiment yield directed motion (ratchet transport), the probability distribution of the individual Floquet states is asymmetric, mirroring the asymmetric N(p) measured in clouds of cesium atoms. In the penultimate chapter, the spectral fluctuations (eigenvalue statis tics) are
Particulate matter and black carbon optical properties and emission factors from prescribed fires in the southeastern United States
This dataset provides all data used to generate the figures and tables in the article entitled Particulate matter and black carbon optical properties and emission factors from prescribed fires in the southeastern United States published in the Journal of Geophysical Research: AtmospheresThis dataset is associated with the following publication:Holder , A., G. Hagler , J. Aurell, M. Hays , and B. Gullett. Particulate matter and black carbon optical properties and emission factors from prescribed fires in the southeastern United States. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES. American Geophysical Union, Washington, DC, USA, 121(7): 3465-3483, (2016).
Resonant-state expansion applied to three-dimensional open optical systems
NASA Astrophysics Data System (ADS)
Doost, M. Â. B.; Langbein, W.; Muljarov, E. Â. A.
The resonant-state expansion (RSE), a rigorous perturbative method in electrodynamics, is developed for three-dimensional open optical systems. Results are presented using the analytically solvable homogeneous dielectric sphere as unperturbed system. Since any perturbation which breaks the spherical symmetry mixes transverse electric (TE) and transverse magnetic (TM) modes, the RSE is extended here to include TM modes and a zero-frequency pole of the Green's function. We demonstrate the validity of the RSE for TM modes by verifying its convergence towards the exact result for a homogeneous perturbation of the sphere. We then apply the RSE to calculate the modes for a selection of perturbations sequentially reducing the remaining symmetry, given by a change of the dielectric constant of half-sphere and quarter-sphere shape. Since no exact solutions are known for these perturbations, we verify the RSE results by comparing them with the results of state of the art finite element method (FEM) and finite difference in time domain (FDTD) solvers. We find that for the selected perturbations, the RSE provides a significantly higher accuracy than the FEM and FDTD for a given computational effort, demonstrating its potential to supersede presently used methods. We furthermore show that in contrast to presently used methods, the RSE is able to determine the perturbation of a selected group of modes by using a limited basis local to these modes, which can further reduce the computational effort by orders of magnitude.
Influence of wetting state on optical reflectance spectra of Si nanopillar arrays
NASA Astrophysics Data System (ADS)
Gwon, Minji; Kim, Sujung; Li, Jiaqi; Xu, Xiumei; Kim, Sun-Kyung; Lee, Eunsongyi; Kim, Dong-Wook; Chen, Chang
Finite-difference time-domain (FDTD) simulations showed that the reflectance spectra of crystalline Si nanopillar (NP) arrays with diameters of 40, 70, 100, and 130 nm differed depending on wetting state. The observed reflectance dips of the 40-nm-diameter NP array were in good agreement with those estimated from destructive interference conditions at the top and bottom of the NPs: the NP arrays were treated as a homogeneous medium with an effective permittivity according to the effective medium approximation model. In contrast, the dip positions of the FDTD-simulated spectra for 70-, 100-, and 130-nm-diameter NP arrays deviated from the results of interference calculations, particularly for short wavelengths. This suggested that Mie resonances in individual NPs significantly increased the absorption cross-section at the resonant wavelengths, which was sensitive to the refractive index of the surrounding medium (i.e., the wetting state). Optical reflectance measurements provide an easy and efficient means of inspecting the wetting behavior of non-flat surfaces.
Gender-related effects of prefrontal cortex connectivity: a resting-state functional optical tomography study
Chuang, Ching-Cheng; Sun, Chia-Wei
The prefrontal cortex (PFC) is thought to play an important role in "higher" brain functions such as personality and emotion that may associated with several gender-related mental disorders. In this study, the gender effects of functional connectivity, cortical lateralization and significantly differences in the PFC were investigated by using resting-state functional optical tomography (fOT) measurement. A total of forty subjects including twenty healthy male and twenty healthy female adults were recruited for this study. In the results, the hemoglobin responses are higher in the male group. Additionally, male group exhibited the stronger connectivity in the PFC regions. In the result of lateralization, leftward dominant was observed in the male group but bilateral dominance in the female group. Finally, the 11 channels of the inferior PFC regions (corresponding to the region of Brodmann area 45) are significant different with spectrum analysis. Our findings suggest that the resting-state fOT method can provide high potential to apply to clinical neuroscience for several gender-related mental disorders diagnosis. PMID:25136481
Quantification of black carbon mixing state from traffic: Implications for aerosol optical properties
Willis, Megan D.; Healy, Robert M.; Riemer, Nicole; West, Matthew; Wang, Jon M.; Jeong, Cheol -Heon; Wenger, John C.; Evans, Greg J.; Abbatt, Jonathan P. D.; Lee, Alex K. Y.
The climatic impacts of black carbon (BC) aerosol, an important absorber of solar radiation in the atmosphere, remain poorly constrained and are intimately related to its particle-scale physical and chemical properties. Using particle-resolved modelling informed by quantitative measurements from a soot-particle aerosol mass spectrometer, we confirm that the mixing state (the distribution of co-emitted aerosol amongst fresh BC-containing particles) at the time of emission significantly affects BC-aerosol optical properties even after a day of atmospheric processing. Both single particle and ensemble aerosol mass spectrometry observations indicate that BC near the point of emission co-exists with hydrocarbon-like organic aerosol (HOA) in two distinct particle types: HOA-rich and BC-rich particles. The average mass fraction of black carbon in HOA-rich and BC-rich particle classes was < 0.1 and 0.8, respectively. Notably, approximately 90 % of BC mass resides in BC-rich particles. This new measurement capability provides quantitative insight into the physical and chemical nature of BC-containing particles and is used to drive a particle-resolved aerosol box model. Lastly, significant differences in calculated single scattering albedo (an increase of 0.1) arise from accurate treatment of initial particle mixing state as compared to the assumption of uniform aerosol composition at the point of BC injection into the atmosphere.
Quantification of black carbon mixing state from traffic: Implications for aerosol optical properties
Willis, Megan D.; Healy, Robert M.; Riemer, Nicole; ...
The climatic impacts of black carbon (BC) aerosol, an important absorber of solar radiation in the atmosphere, remain poorly constrained and are intimately related to its particle-scale physical and chemical properties. Using particle-resolved modelling informed by quantitative measurements from a soot-particle aerosol mass spectrometer, we confirm that the mixing state (the distribution of co-emitted aerosol amongst fresh BC-containing particles) at the time of emission significantly affects BC-aerosol optical properties even after a day of atmospheric processing. Both single particle and ensemble aerosol mass spectrometry observations indicate that BC near the point of emission co-exists with hydrocarbon-like organic aerosol (HOA) inmore » two distinct particle types: HOA-rich and BC-rich particles. The average mass fraction of black carbon in HOA-rich and BC-rich particle classes was < 0.1 and 0.8, respectively. Notably, approximately 90 % of BC mass resides in BC-rich particles. This new measurement capability provides quantitative insight into the physical and chemical nature of BC-containing particles and is used to drive a particle-resolved aerosol box model. Lastly, significant differences in calculated single scattering albedo (an increase of 0.1) arise from accurate treatment of initial particle mixing state as compared to the assumption of uniform aerosol composition at the point of BC injection into the atmosphere.« less
Comparisons of N-state Models for the Nonlinear Optical Properties of Organic and Inorganic Molecules
NASA Astrophysics Data System (ADS)
Ferris, K. F.; Exarhos, G. J.; Risser, S. M.; Wolfgang, J.
While the nonlinear optical properties of materials are frequently interpreted using a two or three state model for the electronic spectrum, systems with a more complex electronic structure require an approach which can denote state importance. In this paper, we examine and compare the electronic origin of the NLO properties for an inorganic polymer (polyphosphazenes) and an organic system (5-CB). In previous work we have shown that the electronic absorption spectrum of these compounds is complicated by localized excitations caused by geometric, charge distribution and symmetry constraints. These effects invoke both multistate and multiconfiguration contributions to the electronic transitions. In particular, the phosphazene system possessing in-plane and out-of-plane pi bonding networks requires a more flexible approach. Electronic structure calculations (NDDO/AM1) will be presented to illustrate the sensitivity of NLO properties to these effects and to suggest methods to control their nonlinearities. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Sciences Division under contract DE-AC06-76RLO 1830.
Optical control of exciton states and enhanced valley Zeeman splitting in WS2(Conference Presentation)
NASA Astrophysics Data System (ADS)
Kioseoglou, George; Currie, Marc; Hanbicki, Aubrey T.; Paradisanos, Ioannis; Stratakis, Emmanuel; Fotakis, Costas; Jonker, Berrend T.
Monolayer transition metal dichalcogenides, MX2 (M = Mo, W and X = S, Se), are direct-gap semiconductors with many interesting properties capable of producing an all-surface material applicable to sensing, single-atom storage and other quantum-based technologies. Here we report on the optical control of single layers of MX2 such that the photoluminescence (PL) is solely from the trion state. After trion isolation, changes in the Raman spectra were observed: there is a decrease in the intensity of the out of plane mode and an enhancement of the 2LA mode. The effect is reversible, and our results suggest that the changes of the strength of a particular excitonic state are due to surface interactions with ambient environment. In addition, spatial non-uniformity is probed by studying variations of strain and the PL emission as a function of position on our sample. The boundaries of mechanically exfoliated MX2 as well as boundaries intentionally created via fs laser ablation were investigated. The edges exhibit significant Raman shifts as well as remarkably enhanced PL emission compared to their respective central area. Finally, we probe the degree of circular polarization of the emitted PL as a function of the photo-excitation energy and temperature to elucidate spin-dependent inter- and intra-valley relaxation mechanisms. This work was supported by the FP7-REGPOT-2012-2013-1, under grant agreement 316165.
Topological semimetal: a probable new state of quantum optical lattice gases protected by D4 symmetry
NASA Astrophysics Data System (ADS)
Sun, Kai; Liu, W. Vincent; Das Sarma, S.
We demonstrate that a novel topological semimetal emerges as a parity-protected critical theory for fermionic atoms loaded in the p and d orbital bands of a two-dimensional optical lattice. The new quantum state is characterized by a parabolic band-degeneracy point with Berry flux 2 π , in sharp contrast to the π flux of Dirac points as in graphene. We prove that this topological liquid is a universal property for all lattices of D4 point group symmetry and the band degeneracy is protected by odd parity. Turning on interparticle repulsive interaction, the system undergoes a phase transition to a topological insulator, whose experimental signature includes chiral gapless domain-wall modes, reminiscent of quantum Hall edge states. KS and SDS acknowledge the support of JQI-NSF-PFC, AFOSR-MURI, ARO-DARPA-OLE and ARO-MURI. W.V.L. is supported by ARO and ARO-DARPA-OLE. We thank the KITP at UCSB for its hospitality where this research is supported in part by NSF Grant No. PHY05-51164.
Optimally moderated nuclear fission reactor and fuel source therefor
Ougouag, Abderrafi M.; Terry, William K.; Gougar, Hans D.
An improved nuclear fission reactor of the continuous fueling type involves determining an asymptotic equilibrium state for the nuclear fission reactor and providing the reactor with a moderator-to-fuel ratio that is optimally moderated for the asymptotic equilibrium state of the nuclear fission reactor; the fuel-to-moderator ratio allowing the nuclear fission reactor to be substantially continuously operated in an optimally moderated state.
Band gap states in nanocrystalline WO3 thin films studied by soft x-ray spectroscopy and optical spectrophotometry
NASA Astrophysics Data System (ADS)
Johansson, M. B.; Kristiansen, P. T.; Duda, L.; Niklasson, G. A.; Österlund, L.
Nanocrystalline tungsten trioxide (WO3) thin films prepared by DC magnetron sputtering have been studied using soft x-ray spectroscopy and optical spectrophotometry. Resonant inelastic x-ray scattering (RIXS) measurements reveal band gap states in sub-stoichiometric γ-WO3-x with x = 0.001-0.005. The energy positions of these states are in good agreement with recently reported density functional calculations. The results were compared with optical absorption measurements in the near infrared spectral region. An optical absorption peak at 0.74 eV is assigned to intervalence transfer of polarons between W sites. A less prominent peak at energies between 0.96 and 1.16 eV is assigned to electron excitation of oxygen vacancies. The latter results are supported by RIXS measurements, where an energy loss in this energy range was observed, and this suggests that electron transfer processes involving transitions from oxygen vacancy states can be observed in RIXS. Our results have implications for the interpretation of optical properties of WO3, and the optical transitions close to the band gap, which are important in photocatalytic and photoelectrochemical applications.
Entanglement purification and concentration of electron-spin entangled states using quantum-dot spins in optical microcavities
Wang Chuan; Zhang Yong; Jin Guangsheng
We present an entanglement purification protocol and an entanglement concentration protocol for electron-spin entangled states, resorting to quantum-dot spin and optical-microcavity-coupled systems. The parity-check gates (PCGs) constructed by the cavity-spin-coupling system provide a different method for the entanglement purification of electron-spin entangled states. This protocol can efficiently purify an electron ensemble in a mixed entangled state. The PCGs can also concentrate electron-spin pairs in less-entangled pure states efficiently. The proposed methods are more flexible as only single-photon detection and single-electron detection are needed.
Chiral optical Tamm states at the boundary of the medium with helical symmetry of the dielectric tensor
NASA Astrophysics Data System (ADS)
Timofeev, I. V.; Vetrov, S. Ya.
A new optical state at the boundary of a chiral medium whose dielectric tensor has a helical symmetry is described analytically and numerically. The case of zero tangential wavenumber is considered. The state localized near the boundary does not transfer energy along this boundary and decreases exponentially with the distance from the boundary. The penetration of the field into the chiral medium is blocked at wavelengths corresponding to the photonic band gap and close to the pitch of the helix. The polarization of light near the boundary has the same sign of chirality as the helical symmetry. It is shown that the homogeneous environment or a substrate should exhibit anisotropic metallic reflection. The spectral manifestation of the state is determined by the angle between the optical axes of the media at the interface. A state at the interface between a cholesteric liquid crystal and an anisotropic metal-dielectric nanocomposite was considered as an example.
Nonlinear optical spectra having characteristics of Fano interferences in coherently coupled lowest exciton biexciton states in semiconductor quantum dots
Gotoh, Hideki Sanada, Haruki; Yamaguchi, Hiroshi; Sogawa, Tetsuomi
Optical nonlinear effects are examined using a two-color micro-photoluminescence (micro-PL) method in a coherently coupled exciton-biexciton system in a single quantum dot (QD). PL and photoluminescence excitation spectroscopy (PLE) are employed to measure the absorption spectra of the exciton and biexciton states. PLE for Stokes and anti-Stokes PL enables us to clarify the nonlinear optical absorption properties in the lowest exciton and biexciton states. The nonlinear absorption spectra for excitons exhibit asymmetric shapes with peak and dip structures, and provide a distinct contrast to the symmetric dip structures of conventional nonlinear spectra. Theoretical analyses with a density matrix method indicate that the nonlinear spectra are caused not by a simple coherent interaction between the exciton and biexciton states but by coupling effects among exciton, biexciton and continuum states. These results indicate that Fano quantum interference effects appear in exciton-biexciton systems at QDs and offer important insights into their physics.
Complete Deterministic Analyzer for Multi-Electron Greenberger-Horne-Zeilinger States Assisted by Double-Side Optical Microcavities
NASA Astrophysics Data System (ADS)
Wei, Hai-Rui; Ren, Bao-Cang; Zhang, Mei; Li, Tao; Deng, Fu-Guo
We present a complete deterministic scheme for the multi-electron Greenberger-Horne-Zeilinger (GHZ) state analyzer, resorting to an interface between the polarization of a probe photon and the spin of an electron in a quantum dot embedded in a double-sided optical microcavity. All the multi-spin GHZ states can be completely discriminated by using single-photon detectors and linear optical elements. Our scheme has some features. First, it is a complete GHZ-state analyzer for multi-electron spin systems. Second, the initial entangled states remain after being identified and they can be used for a successive task. Third, the electron qubits are static and the photons play a role of a medium for information transfer, which has a good application in quantum repeater in which the electron qubits are used to store the information and the photon qubits are used to transfer the information between others.
Numerical investigation of optical Tamm states in two-dimensional hybrid plasmonic-photonic crystal nanobeams
Meng, Zi-Ming E-mail: firstname.lastname@example.com; Hu, Yi-Hua; Ju, Gui-Fang; Zhong, Xiao-Lan; Ding, Wei; Li, Zhi-Yuan E-mail: firstname.lastname@example.com
Optical Tamm states (OTSs) in analogy with its electronic counterpart confined at the surface of crystals are optical surface modes at the interfaces between uniform metallic films and distributed Bragg reflectors. In this paper, OTSs are numerically investigated in two-dimensional hybrid plasmonic-photonic crystal nanobeams (HPPCN), which are constructed by inserting a metallic nanoparticle into a photonic crystal nanobeam formed by periodically etching square air holes into dielectric waveguides. The evidences of OTSs can be verified by transmission spectra and the field distribution at resonant frequency. Similar to OTSs in one-dimensional multilayer structures OTSs in HPPCN can be excited by both TE and TM polarization. The physical origin of OTSs in HPPCN is due to the combined contribution of strong reflection imposed by the photonic band gap (PBG) of the photonic crystal (PC) nanobeam and strong backward scattering exerted by the nanoparticle. For TE, incidence OTSs can be obtained at the frequency near the center of the photonic band gap. The transmissivity and the resonant frequency can be finely tuned by the dimension of nanoparticles. While for TM incidence OTSs are observed for relatively larger metallic nanoparticles compared with TE polarization. The differences between TE and TM polarization can be explained by two reasons. For one reason stronger backward scattering of nanoparticles for TE polarization can be achieved by the excitation of localized surface plasmon polariton of nanoparticles. This assumption has been proved by examining the scattering, absorption, and extinction cross section of the metallic nanoparticle. The other can be attributed to the deep and wide PBG available for TE polarization with less number of air holes compared with TM polarization. Our results show great promise in extending the application scope of OTSs from one-dimensional structures to practical integrated photonic devices and circuits.
Numerical investigation of optical Tamm states in two-dimensional hybrid plasmonic-photonic crystal nanobeams
NASA Astrophysics Data System (ADS)
Meng, Zi-Ming; Hu, Yi-Hua; Ju, Gui-Fang; Zhong, Xiao-Lan; Ding, Wei; Li, Zhi-Yuan
Optical Tamm states (OTSs) in analogy with its electronic counterpart confined at the surface of crystals are optical surface modes at the interfaces between uniform metallic films and distributed Bragg reflectors. In this paper, OTSs are numerically investigated in two-dimensional hybrid plasmonic-photonic crystal nanobeams (HPPCN), which are constructed by inserting a metallic nanoparticle into a photonic crystal nanobeam formed by periodically etching square air holes into dielectric waveguides. The evidences of OTSs can be verified by transmission spectra and the field distribution at resonant frequency. Similar to OTSs in one-dimensional multilayer structures OTSs in HPPCN can be excited by both TE and TM polarization. The physical origin of OTSs in HPPCN is due to the combined contribution of strong reflection imposed by the photonic band gap (PBG) of the photonic crystal (PC) nanobeam and strong backward scattering exerted by the nanoparticle. For TE, incidence OTSs can be obtained at the frequency near the center of the photonic band gap. The transmissivity and the resonant frequency can be finely tuned by the dimension of nanoparticles. While for TM incidence OTSs are observed for relatively larger metallic nanoparticles compared with TE polarization. The differences between TE and TM polarization can be explained by two reasons. For one reason stronger backward scattering of nanoparticles for TE polarization can be achieved by the excitation of localized surface plasmon polariton of nanoparticles. This assumption has been proved by examining the scattering, absorption, and extinction cross section of the metallic nanoparticle. The other can be attributed to the deep and wide PBG available for TE polarization with less number of air holes compared with TM polarization. Our results show great promise in extending the application scope of OTSs from one-dimensional structures to practical integrated photonic devices and circuits.
Calculation of aerosol optical properties under different assumptions on mixing state, refractive index, density and hygroscopicity: uncertainties and importance of representation of aerosol mixing state
NASA Astrophysics Data System (ADS)
Curci, Gabriele
The calculation of aerosol optical properties from aerosol mass is a process subject to uncertainty related to necessary assumptions on the treatment of the chemical species mixing state, density, refractive index, and hygroscopic growth. We used the FlexAOD post-processing tool to calculate the optical properties (aerosol optical depth (AOD), single scattering albedo (SSA) and asymmetry parameter (g)) from chemistry-transport model aerosol profiles, using a wide range of assumptions on aerosol chemical and physical properties. We calculated that the most important factor of uncertainty is the assumption about the mixing state, for which we estimate an uncertainty of 30-35% on the simulated aerosol optical depth (AOD) and single scattering albedo (SSA). The choice of the core composition in the core-shell representation is of minor importance for calculation of AOD, while it is critical for the SSA. Other factors of uncertainty tested here have a maximum average impact of 10% each on calculated AOD, and an impact of a few percent on SSA and g. We then tested simple parameterizations of the aerosol mixing state, expressed as a function of the aerosol aging, and verified that they may be helpful in reducing the uncertainty when comparing simulations with AERONET retrievals.
Bifocal Optical-Vortex Lens with Sorting of the Generated Nonseparable Spin-Orbital Angular-Momentum States
NASA Astrophysics Data System (ADS)
Tam, Alwin M. W.; Fan, Fan; Du, Tao; Hu, Wei; Zhang, Wanlong; Zhao, Chenxiang; Wang, Xiaoqian; Ching, Kwong-Lung; Li, Guijun; Luo, Hailu; Chigrinov, Vladimir G.; Wen, Shuangchun; Kwok, Hoi-Sing
In this article, we devise and demonstrate experimentally a polarization-dependent diffractive bifocal vortex lens operating via the Pancharatnam-Berry phase. The interaction between the incident beam and the bifocal vortex lens establishes nonseparable spin and orbital angular-momentum photon states. The components of the nonseparable state associated with different couplings of spin and orbital angular momentum can be sorted by the bifocality of the lens. A theoretical model of the device is developed using Fresnel's diffraction. The device is simply, efficiently, and economically realized from the optical setup using the underlying physics of Pancharatnam-Berry-phase polarization holography. The measured transmittance and diffraction efficiency of the fabricated device is high—up to 90% and 91%, respectively. Various applications of the polarization bifocal vortex lens in the field of orbital angular-momentum lasing and optical manipulation are discussed. Thus, the bifocal vortex lens can have significant impact on classical and quantum optics, as well as theoretical physics.
Proposal for a probabilistic 'dial-up' generator of Fock states in a traveling-wave optical field
Gerry, Christopher C.; Benmoussa, Adil
We discuss a method for generating Fock (number) states in a single-mode traveling-wave optical field, based on a method we recently proposed for performing a quantum nondemolition measurement of parity and for the generation of parity eigenstates [C. C. Gerry, A. Benmoussa, and R. A. Campos, Phys. Rev. A 72, 053818 (2005)]. The approach is a kind of 'dial-up' scheme that is probabilistic but also depends partially on directed state reductive measurements.
Exact symmetries of electron states and optical selection rules in wurtzite-based nanostructures
NASA Astrophysics Data System (ADS)
Kitaev, Yu. E.; Tronc, P.
The crystal structure of wurtzite-based (hexagonal) quantum wells (QW's), such as (GaN)m/AlN ones for example, is found to be described by the layer group P3m1 (DG69) and does not depend on the number of atomic monolayers constituting the QW whereas the symmetry of wurtzite-based superlattices (SL's), such as (GaN)m(AlN)n ones for example, has been previously shown to be described by the space groups C13v or C46v depending on m+n is even or odd. The P3m1 (DG69) group is a factor group of the C13v group, the latter being the product of the P3m1 group and the subgroup containing the translations along the z axis. Basing on these symmetries, we have determined the exact symmetries of Bloch states at the Γ and other symmetry points of the Brillouin zones of QW's and SL's and derived optical selection rules for carriers and excitons. The latters present large Rydberg values. We have shown that the built-in electric field, directed along the z axis due to the symmetry, breaks the translational invariance of the SL's along this direction reducing their symmetry to that of a single QW. We have established that when one (several) phonon(s) is (are) involved in a radiative process, it is always possible to connect any initial state to any final one. The energy of the emitted photon depends on the nature of the phonon(s) if several channels are allowed for the transition. The symmetry of electron states in very thin QW's and short-period SL's is shown to be determined by their exact symmetry rather than that implied in envelope function approximation (EFA). Within the domain of validity of the EFA, i.e., for not too thin layers, a detailed analysis of the Bloch-state symmetry is performed on imposing the invariance of the structure under the change of z to -z (the σz symmetry operation). The correspondence is established between the symmetry of a Bloch state and the parity with respect to σz of its associated envelope function. It is shown that EFA artificially induces a
Optical characterization of nitride-based light-emitting diodes for solid-state lighting applications
NASA Astrophysics Data System (ADS)
Masui, Hisashi
This dissertation describes research dedicated to the solid-state lighting technology based on III-nitride light-emitting diodes (LEDs). Nitride semiconductors are rather an immature material system compared to conventional III-V semiconductors. As the solid-state lighting technology based on nitride optoelectronic devices becomes widely accepted in the market, solid-state technology is required to compete with the conventional vacuum lighting technology, especially in energy efficiency. In addition to such energy-efficiency requirements, solid-state optoelectronic devices have the potential to explore new applications based on their unique properties. The research was conducted as a way of optical characterization of LEDs with a strong emphasis on electroluminescence. Device-packaging techniques were introduced in the early stage of the research to evaluate performances of discrete LEDs including phosphor-combined white-light emitting devices. Light extraction and white-LED fabrication were of direct interest in terms of solid-state lighting, which occupies a large part of the present dissertation. The suspended-LED technique was introduced to improve light extraction and the sphere package was invented as a result of the technique. A phosphor-combined sphere LED achieved as high as 117 lm/W of luminous efficacy. Low-temperature characterization is important to evaluate light-emission efficiency of LEDs, especially the internal quantum efficiency. It was a generally known problem that electroluminescence efficiency deteriorates drastically at low temperature where photoluminescence efficiency remains high. High-quality LEDs prepared on GaN bulk substrates that became available during the present project contributed to the low-temperature study, largely to address the problem. Electroluminescence is related to carrier generation processes via low-temperature measurements on such high-quality LEDs. This study produced a model to explain electroluminescence
Fast and high-fidelity optical initialization of spin state of an electron in a semiconductor quantum dot using light-hole-trion states
NASA Astrophysics Data System (ADS)
Kumar, Parvendra; Nakajima, Takashi
We theoretically show that under the Faraday geometry fast and high-fidelity optical initialization of electron spin (ES) state in a semiconductor quantum dot (SQD) can be realized by utilizing the light-hole (LH)-trion states. Initialization is completed within the time scale of ten nanoseconds with high fidelity, and the initialization laser pulse can be linearly, right-circularly, or left-circularly polarized. Moreover, we demonstrate that the time required for initialization can be further shortened down to a few hundreds of picoseconds if we introduce a pillar-microcavity to promote the relaxation of a LH-trion state towards the desired ES state through the Purcell effect. We also clarify the role of heavy-hole and light-hole mixing induced transitions on the fidelity of ES state initialization.
Black carbon aerosol optical properties are influenced by initial mixing state
NASA Astrophysics Data System (ADS)
Willis, M. D.; Healy, R. M.; Riemer, N.; West, M.; Wang, J. M.; Jeong, C. H.; Wenger, J.; Abbatt, J.; Lee, A.
Incomplete combustion emits teragram quantities of black carbon (BC) aerosol to the troposphere each year, resulting in a significant warming effect on climate that may be second only to carbon dioxide. The magnitude of BC impacts on a global scale remains poorly constrained and is intimately related to its particle-scale physical and chemical properties. Using particle-resolved modeling informed by novel quantitative measurements from an Aerodyne soot-particle aerosol mass spectrometer (SP-AMS), we show that initial mixing state (or the distribution of co-emitted components amongst fresh BC-containing particles) significantly affects BC-aerosol optical properties even after a day of atmospheric processing. Both single particle and ensemble observations indicate that BC near emission co-exists with hydrocarbon-like organic aerosol (HOA) in two distinct particle types: HOA-rich and BC-rich particles. The average mass fraction of black carbon (mfBC) in HOA- and BC-rich particle types was 0.02-0.08 and 0.72-0.93, respectively. Notably, positive matrix factorization (PMF) analysis of ensemble SP-AMS measurements indicates that BC-rich particles contribute the majority of BC mass (> 90%) in freshly emitted particles. This new measurement capability provides quantitative insight into the physical and chemical nature of BC-containing particles and is used to drive a particle-resolved aerosol box model. Significant differences in calculated single scattering albedo (an increase of 0.1) arise from accurate treatment of initial particle mixing state as compared to the assumption of uniform aerosol composition at the point of BC injection to the atmosphere.
Implementation of a two-state quantum bit commitment protocol in optical fibers
NASA Astrophysics Data System (ADS)
Almeida, Á. J.; Stojanovic, A. D.; Paunković, N.; Loura, R.; Muga, N. J.; Silva, N. A.; Mateus, P.; André, P. S.; Pinto, A. N.
We demonstrate experimentally the feasibility of a two-state quantum bit commitment protocol, which is both concealing and partially binding, assuming technological limitations. The security of this protocol is based on the lack of long-term stable quantum memories. We use a polarization-encoding scheme and optical fiber as a quantum channel. The measurement probability for the commitment is obtained and the optimal cheating strategy demonstrated. The average success rates for an honest player in the case where the measurements are performed using equal bases are 93.4%, when the rectilinear basis is measured, and 96.7%, when the diagonal basis is measured. The rates for the case when the measurements are performed in different bases are 52.9%, when the rectilinear basis is measured, and 55.4% when the diagonal basis is measured. The average success rates for the optimal cheating strategy are 80% and 73.8%, which are way below the success rates of an honest player. Using a strict numerical validity criterion, we show that, for these experimental values, the protocol is secure.
Optical polaron effect on the electronic states of a heterojunction potential
NASA Astrophysics Data System (ADS)
Ban, S. L.; Hasbun, J. E.
The polaron effect contribution to the electronic ground state in a heterojunction potential is investigated by considering the bulk and the interface phonons influence. A self-consistent heterojunction potential is used and an LLP-like method is used to obtain the polaron effect. The GaAs/Al_xGa_1-xAs (0.3
[INVITED] State of the art of Brillouin fiber-optic distributed sensing
NASA Astrophysics Data System (ADS)
Motil, Avi; Bergman, Arik; Tur, Moshe
Fiber-optic distributed sensing, employing the Brillouin effect, is already a commercially available measurement technique for the accurate estimation of the static strain/temperature fields along tens of kilometers with a spatial resolution of the order of a meter. Furthermore, relentless research efforts are paving the way to even much wider usability of the technique through recently achieved enhanced performance in each of its critical dimensions: measurement range has been extended to hundreds of kilometers; spatial resolution is of the order of a centimeter or less, signal to noise ratio has been significantly improved; fast dynamic events can be captured at kHz's sampling rates; and a much better understanding of the underlying physics has been obtained, along with the formulation of figures of merit, and the preparation and early adoption of appropriate standards and guidelines. This paper describes the basics, as well as the state of the art, of the leading Brillouin interrogation methods, with emphasis on the significant progress made in the last 3 years. It also includes a short introduction to coding, which has proven instrumental in many of the recently obtained performance records.
Studying the Equation of State of Isochorically Heated Al Using Streaked Optical Pyrometry
NASA Astrophysics Data System (ADS)
Haberberger, D.; Nilson, P. M.; Gregor, M. C.; Boehly, T. R.; Froula, D. H.
The thermal equilibration rates of warm (few eV) dense (~1023 g/cm3) matter is important in high-energy-density physics. The OMEGA EP laser was used to isochorically heat a 20- μm-thick Al target using a short-pulse beam with 250 J in a 10-ps pulse. Twenty OMEGA beams were used to drive a Ti backlighter to radiograph the expansion of the foil using an x-ray framing camera (XRFC). The short duration of the heating laser pulse and the subsequent hot-electron energy deposition inside the target ensure minimal hydrodynamic expansion during the target heating phase. Streaked optical pyrometry (SOP) was used to measure the surface temperature of the foil. Together, these two measurements can be used to determine the equation of state along the release isentrope of the isochorically heated Al foil. Initial analysis of the SOP and XRFC data indicate the Al foil was heated to temperatures of tens of eV. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.
Optical Tamm states above the bulk plasma frequency at a Bragg stack/metal interface
NASA Astrophysics Data System (ADS)
Brand, S.; Kaliteevski, M. A.; Abram, R. A.
We demonstrate theoretically that surface-plasmon polaritons, a form of optical Tamm state, can occur at the interface between a metal and a Bragg reflector at frequencies above the bulk plasma frequency of the metal. The frequencies of the excitations are within the photonic band gap of the Bragg reflector which provides the required evanescent decay on that side of the interface. At finite in-plane wave vector, the low value of the permittivity of the metal above its plasma frequency can lead to an imaginary normal wave vector component in the metal, which provides the localization on the other side of the interface. It is proposed that the necessary conditions can be realized using a GaAs/AlAs Bragg stack coated with a suitable conducting metal oxide having a bulk plasma frequency of 1 eV, but the concept is valid for other systems given an appropriate plasma frequency and photonic band-gap structure. The dispersion relations of the plasmon polaritons in the structures considered are calculated for both possible polarizations, and it is shown how the excitations result in distinct features in the predicted reflectivity spectra.
The moderating influence of nicotine and smoking on resting-state mood and EEG changes in remitted depressed patients during tryptophan depletion.
Knott, Verner; Bisserbe, Jean-Claude; Shah, Dhrasti; Thompson, Andrea; Bowers, Hayley; Blais, Crystal; Ilivitsky, Vadim
Comorbidity between depression and tobacco use may reflect self-medication of serotonergically mediated mood dysregulation, which has been associated with aberrant cortical activation and hemispheric asymmetry in patients with major depressive disorders (MDD). This randomized, double-blind study in 28 remitted MDD patients examined the moderating effects of acute nicotine and smoker vs. nonsmoker status on mood and EEG changes accompanying transient reductions in serotonin induced by acute tryptophan depletion (ATD). In smokers, who exhibited greater posterior high alpha power and increased left frontal low alpha power (signs of deactivation) compared to nonsmokers, ATD increased self-ratings of depressed mood and elevated left frontal and right parietal high alpha power (i.e. further cortical deactivation). Smokers were not affected by nicotine administration. In nonsmokers, ATD did not influence depression ratings, but it reduced vigor ratings and increased frontal and posterior theta power; both of which were blocked by acute nicotine. These findings indicate a role for nicotinic receptors in disordered mood.
Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator Bi2Se3
Sobota, Jonathan
Using femtosecond time- and angle-resolved photoemission spectroscopy, we investigated the nonequilibrium dynamics of the topological insulator Bi{sub 2}Se{sub 3}. We studied p-type Bi{sub 2}Se{sub 3}, in which the metallic Dirac surface state and bulk conduction bands are unoccupied. Optical excitation leads to a meta-stable population at the bulk conduction band edge, which feeds a nonequilibrium population of the surface state persisting for >10 ps. This unusually long-lived population of a metallic Dirac surface state with spin texture may present a channel in which to drive transient spin-polarized currents.
Reduction of the time-to-full-brightness in solid-state lasers using intra-cavity adaptive optics.
Lubeigt, Walter; Griffith, Mike; Laycock, Leslie; Burns, David
Several adaptive-optics techniques, based on the active modification of the optical properties of the laser cavity, were used to significantly reduce the time-to-full-brightness of solid-state lasers. Resonator re-configuration was achieved using a mechanical translation stage and both multi- and single-element deformable bimorph mirrors. Using these techniques the effects of thermally induced distortion in Nd:YLF and Nd:YAG lasers can be minimized and the warm-up time reduced by a factor of 3-6.
Optics teaching of mathematical students at M.V. Lomonosov Moscow State University in courses of theoretical physics
NASA Astrophysics Data System (ADS)
Makarov, Vladimir A.; Drabovich, Konstantin N.
The concept of teaching in optics and methodical problems of mathematical student's education are discussed. The fundamental knowledge on modern mathematics and of computer- based methods of investigations acquired by students at the first years allows our professors to represent the different branches of optics and photonics at the high scientific level. The methods of teaching have resulted from the more than thirty year's experience of work of the Chair of General Physics and Wave Processes staff of M. V. Lomonosov Moscow State University on training the mathematical students.
Characterization of water molecular state in in-vivo thick tissues using diffuse optical spectroscopic imaging
NASA Astrophysics Data System (ADS)
Chung, So Hyun
Structural changes in water molecules are related to physiological, anatomical and pathological properties of tissues. Near infrared (NIR) optical absorption methods are sensitive to water; however, detailed characterization of water in thick tissues is difficult to achieve because subtle spectral shifts can be obscured by multiple light scattering. In the NIR, a water absorption peak is observed around 975 nm. The precise NIR peak's shape and position are highly sensitive to water molecular disposition. A bound water index (BWI) was developed that quantifies the spectral shift and shape changes observed in tissue water absorption spectra measured by broadband diffuse optical spectroscopic imaging (DOSI). DOSI quantitatively measures light absorption and scattering spectra in cm-deep tissues and therefore reveals bound water spectral shifts. BWI as a water state index was validated by comparing broadband DOSI to MRI and a conductivity cell using bound water phantoms. Non-invasive BWI measurements of malignant and normal tissues in 18 subjects showed a significantly higher fraction of free water in malignant tissues (p<0.0001) compared to normal tissues. BWI showed potential as a prognostic index based on high correlations with tumor grade and size. An algorithm for absolute temperature measurements in deep tissues was developed based on resolving opposing effects of water vibrational frequency shifts due to macromolecular binding. DOSI measures absolute temperature with a difference of 1.1+/-0.91°C from a thermistor. Deep tissue temperature measured in forearms during cold-stress was consistent with previously reported invasively-measured deep tissue temperature. Finally, the BWI was compared to Apparent Diffusion Coefficient (ADC) of diffusion weighted MRI in 9 breast cancer patients. The BWI and ADC correlated (R=0.8, p=<0.01) and both parameters decreased with increasing bulk water content in cancer tissues. Although BWI and ADC are positively correlated in
Allen, G. M.; Broome, T. A.; Burridge, R. A.; Cragg, D.; Hall, R.; Haynes, D.; Hirst, J.; Hogston, J. R.; Jones, H. H.; Sexton, J.; Wright, P.
ISIS is a pulsed spallation neutron source where neutrons are produced by the interaction of a 160 kW proton beam of energy 800 MeV in a water-cooled Tantalum Target. The fast neutrons produced are thermalized in four moderators: two ambient water, one liquid methane operating at 100K and a liquid hydrogen moderator at 20 K. This paper gives a description of the construction of both cold moderator systems, details of the operating experience and a description of the current development program.
The Absurdity of Moderation in War: Is Military Force a Credible Means to Compel United States Political Will in the 21st Century?
tolerances of United States (U.S.) society. However, these constraints are not the direct result of U.S social intolerance or even the nation's founding...as their indigenous adversaries. Due to cultural incompatibility with the indigenous people and the existential nature of the threat they presented...this very concern. Relative intolerance for casualties in the U.S. "can be largely accounted for by several factors: the strength of American
Anomalous optical conductivity in the normal state of high Tc oxides
NASA Astrophysics Data System (ADS)
Moriya, Toru; Takahashi, Yoshinori
The optical resistivity due to antiferromagnetic spin fluctuations in two-dimensional metals, as a possible model for high Tc oxides, is calculated within the Born approximation and the self-consistent renormalization (SCR) theory for the spin fluctuations. The result is shown to explain the observed anomalous behavior of optical conductivity in YBa2Cu3O7 above Tc quantitatively.
Parallel Optical Random Access Memory (PORAM)
NASA Technical Reports Server (NTRS)
Alphonse, G. A.
It is shown that the need to minimize component count, power and size, and to maximize packing density require a parallel optical random access memory to be designed in a two-level hierarchy: a modular level and an interconnect level. Three module designs are proposed, in the order of research and development requirements. The first uses state-of-the-art components, including individually addressed laser diode arrays, acousto-optic (AO) deflectors and magneto-optic (MO) storage medium, aimed at moderate size, moderate power, and high packing density. The next design level uses an electron-trapping (ET) medium to reduce optical power requirements. The third design uses a beam-steering grating surface emitter (GSE) array to reduce size further and minimize the number of components.
Parallel Optical Random Access Memory (PORAM)
NASA Astrophysics Data System (ADS)
Alphonse, G. A.
It is shown that the need to minimize component count, power and size, and to maximize packing density require a parallel optical random access memory to be designed in a two-level hierarchy: a modular level and an interconnect level. Three module designs are proposed, in the order of research and development requirements. The first uses state-of-the-art components, including individually addressed laser diode arrays, acousto-optic (AO) deflectors and magneto-optic (MO) storage medium, aimed at moderate size, moderate power, and high packing density. The next design level uses an electron-trapping (ET) medium to reduce optical power requirements. The third design uses a beam-steering grating surface emitter (GSE) array to reduce size further and minimize the number of components.
Formation of oxygen vacancies and Ti3+ state in TiO2 thin film and enhanced optical properties by air plasma treatment
Bharti, Bandna; Kumar, Santosh; Lee, Heung-No; Kumar, Rajesh
This is the first time we report that simply air plasma treatment can also enhances the optical absorbance and absorption region of titanium oxide (TiO2) films, while keeping them transparent. TiO2 thin films having moderate doping of Fe and Co exhibit significant enhancement in the aforementioned optical properties upon air plasma treatment. The moderate doping could facilitate the formation of charge trap centers or avoid the formation of charge recombination centers. Variation in surface species viz. Ti3+, Ti4+, O2−, oxygen vacancies, OH group and optical properties was studied using X-ray photon spectroscopy (XPS) and UV-Vis spectroscopy. The air plasma treatment caused enhanced optical absorbance and optical absorption region as revealed by the formation of Ti3+ and oxygen vacancies in the band gap of TiO2 films. The samples were treated in plasma with varying treatment time from 0 to 60 seconds. With the increasing treatment time, Ti3+ and oxygen vacancies increased in the Fe and Co doped TiO2 films leading to increased absorbance; however, the increase in optical absorption region/red shift (from 3.22 to 3.00 eV) was observed in Fe doped TiO2 films, on the contrary Co doped TiO2 films exhibited blue shift (from 3.36 to 3.62 eV) due to Burstein Moss shift. PMID:27572095
Formation of oxygen vacancies and Ti(3+) state in TiO2 thin film and enhanced optical properties by air plasma treatment.
Bharti, Bandna; Kumar, Santosh; Lee, Heung-No; Kumar, Rajesh
This is the first time we report that simply air plasma treatment can also enhances the optical absorbance and absorption region of titanium oxide (TiO2) films, while keeping them transparent. TiO2 thin films having moderate doping of Fe and Co exhibit significant enhancement in the aforementioned optical properties upon air plasma treatment. The moderate doping could facilitate the formation of charge trap centers or avoid the formation of charge recombination centers. Variation in surface species viz. Ti(3+), Ti(4+), O(2-), oxygen vacancies, OH group and optical properties was studied using X-ray photon spectroscopy (XPS) and UV-Vis spectroscopy. The air plasma treatment caused enhanced optical absorbance and optical absorption region as revealed by the formation of Ti(3+) and oxygen vacancies in the band gap of TiO2 films. The samples were treated in plasma with varying treatment time from 0 to 60 seconds. With the increasing treatment time, Ti(3+) and oxygen vacancies increased in the Fe and Co doped TiO2 films leading to increased absorbance; however, the increase in optical absorption region/red shift (from 3.22 to 3.00 eV) was observed in Fe doped TiO2 films, on the contrary Co doped TiO2 films exhibited blue shift (from 3.36 to 3.62 eV) due to Burstein Moss shift.
Formation of oxygen vacancies and Ti3+ state in TiO2 thin film and enhanced optical properties by air plasma treatment
NASA Astrophysics Data System (ADS)
Bharti, Bandna; Kumar, Santosh; Lee, Heung-No; Kumar, Rajesh
This is the first time we report that simply air plasma treatment can also enhances the optical absorbance and absorption region of titanium oxide (TiO2) films, while keeping them transparent. TiO2 thin films having moderate doping of Fe and Co exhibit significant enhancement in the aforementioned optical properties upon air plasma treatment. The moderate doping could facilitate the formation of charge trap centers or avoid the formation of charge recombination centers. Variation in surface species viz. Ti3+, Ti4+, O2‑, oxygen vacancies, OH group and optical properties was studied using X-ray photon spectroscopy (XPS) and UV-Vis spectroscopy. The air plasma treatment caused enhanced optical absorbance and optical absorption region as revealed by the formation of Ti3+ and oxygen vacancies in the band gap of TiO2 films. The samples were treated in plasma with varying treatment time from 0 to 60 seconds. With the increasing treatment time, Ti3+ and oxygen vacancies increased in the Fe and Co doped TiO2 films leading to increased absorbance; however, the increase in optical absorption region/red shift (from 3.22 to 3.00 eV) was observed in Fe doped TiO2 films, on the contrary Co doped TiO2 films exhibited blue shift (from 3.36 to 3.62 eV) due to Burstein Moss shift.
Three-dimensional Doppler, polarization-gradient, and magneto-optical forces for atoms and molecules with dark states
NASA Astrophysics Data System (ADS)
Devlin, J. A.; Tarbutt, M. R.
We theoretically investigate the damping and trapping forces in a three-dimensional magneto-optical trap (MOT), by numerically solving the optical Bloch equations. We focus on the case where there are dark states because the atom is driven on a 'type-II' system where the angular momentum of the excited state, F\\prime , is less than or equal to that of the ground state, F. For these systems we find that the force in a three-dimensional light field has very different behaviour to its one dimensional counterpart. This differs from the more commonly used 'type-I' systems (F\\prime =F+1) where the 1D and 3D behaviours are similar. Unlike type-I systems where, for red-detuned light, both Doppler and sub-Doppler forces damp the atomic motion towards zero velocity, in type-II systems in 3D, the Doppler force and polarization gradient force have opposite signs. As a result, the atom is driven towards a non-zero equilibrium velocity, v 0, where the two forces cancel. We find that {v}02 scales linearly with the intensity of the light and is fairly insensitive to the detuning from resonance. We also discover a new magneto-optical force that alters the normal MOT force at low magnetic fields and whose influence is greatest in the type-II systems. We discuss the implications of these findings for the laser cooling and magneto-optical trapping of molecules where type-II transitions are unavoidable in realising closed optical cycling transitions.
Ultra-fast solid state electro-optical modulator based on liquid crystal polymer and liquid crystal composites
Ouskova, Elena; Sio, Luciano De Vergara, Rafael; Tabiryan, Nelson; White, Timothy J.; Bunning, Timothy J.
A different generation of polymer-dispersed liquid crystals (PDLCs) based on a liquid crystalline polymer host is reported wherein the fluid behavior of the reactive mesogenic monomer is an enabler to concentration windows (liquid crystal polymer/liquid crystal) (and subsequent morphologies) not previously explored. These liquid crystal (LC) polymer/LC composites, LCPDLCs, exhibit excellent optical and electro-optical properties with negligible scattering losses in both the ON and OFF states. These systems thus have application in systems where fast phase modulation of optical signal instead of amplitude control is needed. Polarized optical microscopy and high resolution scanning electron microscopy confirm a bicontinuous morphology composed of aligned LC polymer coexisting with a phase separated LC fluid. Operating voltages, switching times, and spectra of LCPDLCs compare favourably to conventional PDLC films. The LCPDLCs exhibit a low switching voltage (4–5 V/μm), symmetric and submillisecond (200 μs) on/off response times, and high transmission in both the as formed and switched state in a phase modulation geometry.
New optical field and its Wigner function obtained by partial tracing over one- and two-mode combinatorial squeezed state
NASA Astrophysics Data System (ADS)
Wang, Tong-Tong; Fan, Hong-Yi
Based on the one- and two-mode combinatorial squeezed state (H.Y. Fan, Phys. Rev. A. 41(3), 1526 (1990))which can enhance squeezing effect, we derive a new optical field by using partial tracing method, we not only obtain its density operator but also deduce its Wigner function by virtue of operators' Weyl ordering property. This new photon field possesses more photon numbers than the corresponding chaotic field, and can be applied to quantum controlling and quantum information processing.
Imaging of quantum Hall edge states under quasiresonant excitation by a near-field scanning optical microscope
Ito, H.; Shibata, Y.; Mamyoda, S.; Ootuka, Y.; Nomura, S.; Kashiwaya, S.; Yamaguchi, M.; Akazaki, T.; Tamura, H.
A high resolution mapping of quantum Hall edge states has been performed by locally creating electrons with small excess energies with a near-field scanning optical microscope in a dilution refrigerator. We have observed fine structures parallel to the edge in photovoltage signals, which appear only at low temperature. The observed fine structures near sample edges have been seen to shift inward with increase in magnetic field in accordance with Chklovskii Shklovskii, and Glazman model.
Entanglement, Einstein Podolsky Rosen correlations and Schrodinger cat state generation by quantum-injected optical parametric amplification
NASA Astrophysics Data System (ADS)
DeMartini, Francesco; Sciarrino, Fabio
We investigate the multi-photon quantum superposition state generated by the quantum-injected high-gain optical parametric amplification of a single photon. The physical configurations based on the optimal universal and on the phase-covariant quantum cloning have been adopted. The theoretical results are supported by a set of experiments leading to the generation of an average number of clones in excess of 103.
Non-local Optical Topological Transitions and Critical States in Electromagnetic Metamaterials
Ishii, Satoshi; Narimanov, Evgenii
Just as the topology of the Fermi surface defines the properties of the free electrons in metals and semiconductors, the geometry of the iso-frequency surface in the phase space of the propagating electromagnetic waves, determines the optical properties of the corresponding optical materials. Furthermore, in the direct analog to the Lifshitz transition in condensed matter physics, a change in the topology of iso-frequency surface has a dramatic effect on the emission, propagation and scattering of the electromagnetic waves. Here, we uncover a new class of such optical topological transitions in metamaterials, induced by the non-locality of the electromagnetic response inherent to these composites. PMID:26670600
Moderating strain without sacrificing reactivity: design of fast and tunable noncatalyzed alkyne-azide cycloadditions via stereoelectronically controlled transition state stabilization.
Gold, Brian; Dudley, Gregory B; Alabugin, Igor V
Recently, we have identified two strategies for selective transition state (TS) stabilization in catalyst-free azide/alkyne cycloadditions. In particular, the transition states for the formation of both 1,4- and 1,5-isomers can be stabilized via hyperconjugative assistance for the C···N bond formation, whereas the 1,5-TS can be stabilized via C-H···X H-bonding interactions. When the hyperconjugative assistance is maximized by the antiperiplanar arrangement of propargylic σ-acceptors relative to the forming bonds, the combination of these TS-stabilizing effects was predicted to lead to ~1 million fold acceleration of the cycloaddition with methyl azide. The present work investigated whether hyperconjugative assistance and H-bonding can be combined with strain activation for the design of even more reactive alkynes and whether reactivity can be turned "on demand." When stereoelectronic amplification is achieved by optimal positioning of σ-acceptors at the endocyclic bonds antiperiplanar to the breaking alkyne π-bonds, the stabilization of the bent alkyne geometry leads to a significant decrease in strain in cyclic alkynes without compromising their reactivity in alkyne-azide cycloadditions. The approach can be used in a modular fashion where the TS stabilizing effects are introduced sequentially until the desired level of reactivity is achieved. A significant increase in reactivity upon the protonation of an endocyclic NH-group suggests a new strategy for the design of click reactions triggered by a pH-change or introduction of an external Lewis acid.
Anomalous evolution of broadband optical absorption reveals dynamic solid state reorganization during eumelanin build-up in thin films.
Bonavolontà, Carmela; Lisio, Corrado de; d'Ischia, Marco; Maddalena, Pasqualino; Manini, Paola; Pezzella, Alessandro; Valentino, Massimo
The origin of eumelanin optical properties remains a formidable conundrum preventing a detailed understanding of the complex photo-protective role of these widespread natural pigments and the rational design of innovative bioinspired materials for optoelectronic applications. Here we report the unusual kinetic and thickness-dependent evolution of the optical properties of black eumelanin polymers generated by spontaneous aerial polymerization of 5,6-dihydroxyindole (DHI) thin films (0.1-1 μm), consistent with peculiar solid state reorganization mechanisms governing broadband absorption. The complete reversal of eumelanin UV-visible transmittance spectrum curvature on passing from 0.2 to 0.5 μm thick films, the marked increase in visible extinction coefficients with increasing film thickness and the higher UV extinction coefficients in slowly vs. rapidly generated polymers concur to support distinct dynamic regimes of solid-state molecular reorganization at the nanoscale level and to do affect the development of broadband visible absorption. Solid state control of molecular reorganization disclosed herein may delineate new rational strategies for tuning optical properties in eumelanin thin films for optoelectronic applications.
Multimode optical feedback dynamics of InAs/GaAs quantum-dot lasers emitting on different lasing states
NASA Astrophysics Data System (ADS)
Huang, H.; Arsenijević, D.; Schires, K.; Sadeev, T.; Bimberg, D.; Grillot, F.
Quantum dot lasers are envisioned to be the next generation of optical transmitters used for short-reach communication links, owing to their low threshold current and high temperature operation. However, in a context of steady increase in both speed and reach, quantum dot lasers emitting on their upper energy levels have been recently of greater interest as they are touted for their faster modulation dynamics. This work aims at further evaluating the potential impact of such lasers in communication links by characterizing their long-delay optical feedback responses as well as the role of the lasing states on the multimode dynamics of InAs/GaAs quantum-dot Fabry-Perot devices sharing the same design. Results unveil that the excited-state laser shows a much larger sensitivity to optical feedback, with a more complex route to chaos, and a first destabilization point occurring at lower feedback strengths than for a comparable ground-state laser, which remains almost unaffected.
Line space theory of Resonant Four-Wave Mixing: New prospects for all-optical studies of photofragment states
NASA Astrophysics Data System (ADS)
Kouzov, A. P.; Radi, P. P.
Based on the line-space quantum formalism, the potential of Resonant Four-Wave Mixing spectroscopy as a new tool to study rotational and translational anisotropy of photofragments produced by absorption of plane-polarized photons is theoretically addressed. Synergy of the flexible polarization setup, fine quantum state resolution and of the possibility to study translational recoil distributions, makes the tool unsurpassed among the all-optical means to interrogate the photofragment states. It allows to directly separate signals induced by the rotational anisotropy which remain silent in the most of laser-induced fluorescence responses and thus opens new ways to study rotational helicity, a crucial signature of the photolysis pathway.
The current state of the international standard for exchange of optical data in electronic form
NASA Astrophysics Data System (ADS)
Wormell, Prudence M. J. H.
The International Organization for Standardization (ISO) is developing a standard for the exchange of optical data in electronic form between different design programs. In order that the data be completely unambiguous an on-line Properties Dictionary is also being established, when finished this should be available to subscribers to ISO and will enable optical designers and manufacturing industry to access information accurately and transfer this information without manual intervention, across many boundaries. The Neutral Optical Data Interchange Format (NODIF) will use this dictionary to define the optical data that can be passed between to any CAD programs that are STEP compliant. NODIF is of concern to software developers, the Properties Dictionary is of concern to manufacturers.
Design and modeling of electro-optomechanical devices for microwave to optical quantum state transfer
NASA Astrophysics Data System (ADS)
Burns, P. S.; Andrews, R. W.; Peterson, R. W.; Purdy, T. P.; Cicak, K.; Simmonds, R. W.; Regal, C. A.; Lehnert, K. W.
A transducer that could transfer quantum information between the microwave and optical domains would connect the information processing and storage power of superconducting qubits with the long distance communication power of light in optical fibers. Electro-optomechanical structures, which parametrically couple mechanical vibration to both optical and microwave resonantors, have emerged as promising candidates for realizing such a transducer. Following on the recent demonstration of bidirectional and efficient conversion of classical information between the microwave and optical domains, we report on the design of improved electro-optomechnical transducers. These new transducers are designed to operate with higher conversion bandwidth and in a dilution refrigerator, thereby reaching the regime of quantum transduction. This Research is funded by AFOSR and MURI.
Real-space imaging of a topologically protected edge state with ultracold atoms in an amplitude-chirped optical lattice
Leder, Martin; Grossert, Christopher; Sitta, Lukas; Genske, Maximilian; Rosch, Achim; Weitz, Martin
To describe a mobile defect in polyacetylene chains, Su, Schrieffer and Heeger formulated a model assuming two degenerate energy configurations that are characterized by two different topological phases. An immediate consequence was the emergence of a soliton-type edge state located at the boundary between two regions of different configurations. Besides giving first insights in the electrical properties of polyacetylene materials, interest in this effect also stems from its close connection to states with fractional charge from relativistic field theory. Here, using a one-dimensional optical lattice for cold rubidium atoms with a spatially chirped amplitude, we experimentally realize an interface between two spatial regions of different topological order in an atomic physics system. We directly observe atoms confined in the edge state at the intersection by optical real-space imaging and characterize the state as well as the size of the associated energy gap. Our findings hold prospects for the spectroscopy of surface states in topological matter and for the quantum simulation of interacting Dirac systems. PMID:27767054
Single-resonance optical pumping spectroscopy and application in dressed-state measurement with atomic vapor cell at room temperature.
Liang, Qiangbing; Yang, Baodong; Zhang, Tiancai; Wang, Junmin
By monitoring the transmission of probe laser beam (also served as coupling laser beam) which is locked to a cycling hyperfine transition of cesium D(2) line, while pumping laser is scanned across cesium D(1) or D(2) lines, the single-resonance optical pumping (SROP) spectra are obtained with atomic vapor cell. The SROP spectra indicate the variation of the zero-velocity atoms population of one hyperfine fold of ground state, which is optically pumped into another hyperfine fold of ground state by pumping laser. With the virtue of Doppler-free linewidth, high signal-to-noise ratio (SNR), flat background and elimination of crossover resonance lines (CRLs), the SROP spectra with atomic vapor cell around room temperature can be employed to measure dressed-state splitting of ground state, which is normally detected with laser-cooled atomic sample only, even if the dressed-state splitting is much smaller than the Doppler-broaden linewidth at room temperature.
Femtosecond excited-state absorption dynamics and optical limiting in fullerene solutions, sol-gel glasses, and thin films
McBranch, D.; Klimov, V.; Smilowitz, L.; Wang, H.; Wudl, F.
We compare detailed dynamics of the excited-state absorption for C{sub 60} in solution, thin films, and entrapped in an inorganic sol-gel glass matrix. Our results demonstrate that the microscopic morphology of the C{sub 60} molecule plays a crucial role in determining the relaxation dynamics. This is a key factor for applications in optical limiting for nanosecond pulses using reverse saturable absorption. We find that the dynamics of the C{sub 60}-glass composite occur on long (ns) timescales, comparable to that in solution; thin film samples, by contrast, show rapid decay (<20 picoseconds). These results demonstrate that the C{sub 60}-sol-gel glass composites contain C{sub 60} in a molecular dispersion, and are suitable candidates for solid-state optical limiting. Multispectral analysis of the decay dynamics in solution allows accurate determination of both the intersystem crossing time (600 {+-}100 ps) and the relative strengths of the singlet and triplet excited-state cross sections as a function of wavelength from 450-950 nm. The triplet excited-state cross section is greater than that for the singlet excited-state over the range from 620-810 nm.
Pump-probe scheme to study the autoionization decay of optically-forbidden H2 doubly excited states.
Rivière, P; Silva, R E F; Martín, F
A pump-probe scheme is proposed to investigate the autoionization dynamics of the optically forbidden Q(1)(1)Σ(g)(+) doubly excited states of the H(2) molecule. The scheme consists of a pump that contains an attosecond pulse train (APT) and an infrared (IR) pulse, which is phase-locked with the APT, and an IR probe identical to the former IR pulse. The dynamical information is obtained by analyzing the electron kinetic energy spectra (EKE) and proton kinetic energy spectra (PKE) as a function of the time delay between the pump and the probe. The essential requirement for an efficient population of the Q(1)(1)Σ(g)(+) states is that they are resonantly coupled to both the dipole-allowed Q(1)(1)Σ(u)(+) doubly excited states and the ground state of H(2) by the combined effect of the APT + IR fields.
Gated THz magneto-optics of the Quantum spin Hall state in InAs/GaSb double quantum wells
NASA Astrophysics Data System (ADS)
Jenkins, Gregory S.; Sushkov, Andrei B.; Carey, Remington L.; Drew, H. Dennis; Sullivan, Gerard; Du, Lingjie; Du, Rui-Rui
Gate-modulated THz cyclotron resonance and Kerr effect are used to characterize the electronic structure and the roles of hybridization and excitonic effects in band inverted InAs/GaSb quantum wells. In contrast to previous optical studies, a gate tunes the chemical potential through the hybridization gap. Measured magnetic state transitions are used to delineate the inverted gap which is thought to determine the observed large critical field transition Bc from the non-trivial Z2 state to the trivial Z state of the system as predicted by the Benevig-Hughes-Zhang (BHZ) model, as well as transitions from the quantum spin Hall to Quantum Hall Effect regimes, as a function of gate, frequency, and magnetic field. Evidence for excitonic condensation using zero field THz Kerr rotation to detect broken time reversal ground states will be discussed. UMD supported by DOE #ER-46741-SC0005436, Rice by DOE #DE-FG02-06ER46274.
State-of-the-art fiber optics for short distance frequency reference distribution
NASA Technical Reports Server (NTRS)
Lutes, G. F.; Primas, L. E.
A number of recently developed fiber-optic components that hold the promise of unprecedented stability for passively stabilized frequency distribution links are characterized. These components include a fiber-optic transmitter, an optical isolator, and a new type of fiber-optic cable. A novel laser transmitter exhibits extremely low sensitivity to intensity and polarization changes of reflected light due to cable flexure. This virtually eliminates one of the shortcomings in previous laser transmitters. A high-isolation, low-loss optical isolator has been developed which also virtually eliminates laser sensitivity to changes in intensity and polarization of reflected light. A newly developed fiber has been tested. This fiber has a thermal coefficient of delay of less than 0.5 parts per million per deg C, nearly 20 times lower than the best coaxial hardline cable and 10 times lower than any previous fiber-optic cable. These components are highly suitable for distribution systems with short extent, such as within a Deep Space Communications Complex. Here, these new components are described and the test results presented.
Fraas, A.P.; Tudor, J.J.
An improved moderator structure for nuclear reactors consists of moderator blocks arranged in horizontal layers to form a multiplicity of vertically stacked columns of blocks. The blocks in each vertical column are keyed together, and a ceramic grid is disposed between each horizontal layer of blocks. Pressure plates cover- the lateral surface of the moderator structure in abutting relationship with the peripheral terminal lengths of the ceramic grids. Tubular springs are disposed between the pressure plates and a rigid external support. The tubular springs have their axes vertically disposed to facilitate passage of coolant gas through the springs and are spaced apart a selected distance such that at sonae preselected point of spring deflection, the sides of the springs will contact adjacent springs thereby causing a large increase in resistance to further spring deflection. (AEC)
Lucas, A. T.
The Advanced Neutron Source (ANS) cold moderators were not an 'Oak Ridge first', but would have been the largest both physically and in terms of cold neutron flux. Two cold moderators were planned each 410 mm in diameter and containing about 30L of liquid deuterium. They were to be completely independent of each other. A modular system design was used to provide greater reliability and serviceability. When the ANS was terminated, up–grading of the resident High Flux Isotope Reactor (HFIR) was examined and an initial study was made into the feasibility of adding a cold source. Because the ANS design was modular, it was possible to use many identical design features. Sub-cooled liquid at 4 bar abs was initially chosen for the HFIR design concept, but this was subsequently changed to 15 bar abs to operate above the critical pressure. As in the ANS, the hydrogen will operate at a constant pressure throughout the temperature range and a completely closed loop with secondary containment was adopted. The heat load of 2 kW made the heat flux comparable with that of the ANS. Subsequent studies into the construction of cryogenic moderators for the proposed new Synchrotron Neutron source indicated that again many of the same design concepts could be used. By connecting the two cold sources together in series, the total heat load of 2 kW is very close to that of the HFIR allowing a very similar supercritical hydrogen system to be configured. The two hydrogen moderators of the SNS provide a comparable heat load to the HFIR moderator. It is subsequently planned to connect the two in series and operate from a single cold loop system, once again using supercritical hydrogen. The spallation source also provided an opportunity to re-examine a cold pellet solid methane moderator operating at 20K.
Steady-state numerical solution of the Navier-Stokes and energy equations around a horizontal cylinder at moderate Reynolds numbers from 100 to 500
Ahmad, R.A.
A numerical analysis of forced-convection heat transfer from a horizontal stationary circular cylinder dissipating a uniform heat flux in a crossflow of air is conducted by solving the full two-dimensional steady-state Navier-Stokes and energy equations in the range of the Reynolds numbers from 100 to 500 (based on diameter). A numerical study by this author for Reynolds numbers less than 100 was previously conducted and therefore is not repeated here. Dependence on the Reynolds number of the flow and thermal fields, vorticity and pressure distributions, separation angle, drag coefficient, and local and average Nusselt number around the cylinder are shown. Correlations for the separation angle and drag coefficient as functions of Reynolds number are suggested. Quantities such as vorticity, pressure, and Nusselt number at the forward and rear (base) stagnation points are also calculated and correlated as functions of Reynolds number. The local and average values of the Nusselt numbers are shown to be in good agreement with available correlations and experiments. The average forced-convection Nusselt number is correlated. A new correlation for the mean value of forced-convection Nusselt number based on 27 previous studies, including the present results, is proposed. Theoretical predictions and available experimental data are found to be in agreement. Theoretical prediction of the thermal field has no precedence. Flow control methods (which may be possible when turbulence is understood) to stabilize unstable solutions may lead to significant new classes of flows, which at first may be studied numerically more easily and cheaply. The extensive comparison and literature survey given in this article have shown that this fundamental problem is one of such continuing interest, at least from the perspective of fluid flow studies.
Expectation Value Theorem for Thermo Vacuum States of Optical Chaotic Field and Negative-Binomial Field
NASA Astrophysics Data System (ADS)
Wan, Zhi-Long; Fan, Hong-Yi
For the density operator (mixed state) describing chaotic light and negative-binomial field there exist the corresponding thermal vacuum state (pure state) in the real-fictitious space. Using the method of integration within ordered product of operators we find the expectation value theorem in these two thermo vacuum states respectively. The thermal average theorem of translation operator is also deduced. Application of the new thermo vacuum state in calculating photon number disturibution and fluctuation and thermal average is presented.
State-of-the-art thin film X-ray optics for synchrotrons and FEL sources
NASA Astrophysics Data System (ADS)
Hertlein, Frank; Wiesmann, Jörg; Michaelsen, Carsten; Störmer, Michael; Seifert, Andreas
Selected aspects of simulation, preparation and characterization of total reflection and multilayer X-ray optics will be discussed. The best multilayer is found by calculating the optical properties of the coating. Sophisticated improvements in deposition technology allow the precise realization of the specified parameters when manufacturing the X-ray optics. The quality of the shape of the substrate for the optics is measured with the aid of profilometry. X-ray reflectometry measures both film thickness as well as their lateral gradient. Last but not least we will be showing results of the development of carbon coatings as total reflection mirrors for FEL (free electron laser) sources. Over the past years we have developed optimized optics for the XUV range up to 200 eV. First FEL irradiation tests have shown that carbon coatings offer high reflectivity > 95%, high radiation stability, good uniformity in thickness and roughness. An optimized coating of two stripes for different beam energies was produced especially for a tomography beamline, where a Ru/C multilayer was chosen for energies between 10 and 22 keV and a W/Si multilayer for energies between 22 and 45 keV.
Ground states of a Bose-Einstein Condensate in a one-dimensional laser-assisted optical lattice
NASA Astrophysics Data System (ADS)
Sun, Qing; Hu, Jie; Wen, Lin; Liu, W.-M.; Juzeliūnas, G.; Ji, An-Chun
We study the ground-state behavior of a Bose-Einstein Condensate (BEC) in a Raman-laser-assisted one-dimensional (1D) optical lattice potential forming a multilayer system. We find that, such system can be described by an effective model with spin-orbit coupling (SOC) of pseudospin (N-1)/2, where N is the number of layers. Due to the intricate interplay between atomic interactions, SOC and laser-assisted tunnelings, the ground-state phase diagrams generally consist of three phases-a stripe, a plane wave and a normal phase with zero-momentum, touching at a quantum tricritical point. More important, even though the single-particle states only minimize at zero-momentum for odd N, the many-body ground states may still develop finite momenta. The underlying mechanisms are elucidated. Our results provide an alternative way to realize an effective spin-orbit coupling of Bose gas with the Raman-laser-assisted optical lattice, and would also be beneficial to the studies on SOC effects in spinor Bose systems with large spin.
Ground states of a Bose-Einstein Condensate in a one-dimensional laser-assisted optical lattice
Sun, Qing; Hu, Jie; Wen, Lin; Liu, W.-M.; Juzeliūnas, G.; Ji, An-Chun
We study the ground-state behavior of a Bose-Einstein Condensate (BEC) in a Raman-laser-assisted one-dimensional (1D) optical lattice potential forming a multilayer system. We find that, such system can be described by an effective model with spin-orbit coupling (SOC) of pseudospin (N-1)/2, where N is the number of layers. Due to the intricate interplay between atomic interactions, SOC and laser-assisted tunnelings, the ground-state phase diagrams generally consist of three phases–a stripe, a plane wave and a normal phase with zero-momentum, touching at a quantum tricritical point. More important, even though the single-particle states only minimize at zero-momentum for odd N, the many-body ground states may still develop finite momenta. The underlying mechanisms are elucidated. Our results provide an alternative way to realize an effective spin-orbit coupling of Bose gas with the Raman-laser-assisted optical lattice, and would also be beneficial to the studies on SOC effects in spinor Bose systems with large spin. PMID:27883037
Dewitt, L.V.; Gibbs, A.; Lambert, D.P.; Bohrer, S.R.; Fanning, R.L.; Houston, M.W.; Stinson, S.L.; Deible, R.W.; Abdel-Khalik, S.I.
Over the past fifteen months, the Systems Chemistry Group of the Reactor Engineering Department has undertaken a comprehensive study of the Department`s moderator chemistry program at Savannah River Site (SRS). An internal review was developed to formalize and document this program. Objectives were as outlined in a mission statement and action plan. In addition to the mission statement and action plan, nine separate task reports have been issued during the course of this study. Each of these task reports is included in this document as a chapter. This document is an organized compilation of the individual reports issued by the Systems Chemistry Group in assessment of SRS moderator chemistry to determine if there were significant gaps in the program as ft existed in October, 1989. While these reviews found no significant gaps in that mode of operation, or any items that adversely affected safety, items were identified that could be improved. Many of the items have already been dear with or are in the process of completion under this Moderator Chemistry Program and other Reactor Restart programs. A complete list of the items of improvement found under this assessment is found in Chapter 9, along with a proposed time table for correcting remaining items that can be improved for the chemistry program of SRS reactors. An additional external review of the moderator chemistry processes, recommendations, and responses to/from the Reactor Corrosion Mitigation Committee is included as Appendix to this compilation.
Dewitt, L.V.; Gibbs, A.; Lambert, D.P.; Bohrer, S.R.; Fanning, R.L.; Houston, M.W.; Stinson, S.L.; Deible, R.W.; Abdel-Khalik, S.I.
Over the past fifteen months, the Systems Chemistry Group of the Reactor Engineering Department has undertaken a comprehensive study of the Department's moderator chemistry program at Savannah River Site (SRS). An internal review was developed to formalize and document this program. Objectives were as outlined in a mission statement and action plan. In addition to the mission statement and action plan, nine separate task reports have been issued during the course of this study. Each of these task reports is included in this document as a chapter. This document is an organized compilation of the individual reports issued by the Systems Chemistry Group in assessment of SRS moderator chemistry to determine if there were significant gaps in the program as ft existed in October, 1989. While these reviews found no significant gaps in that mode of operation, or any items that adversely affected safety, items were identified that could be improved. Many of the items have already been dear with or are in the process of completion under this Moderator Chemistry Program and other Reactor Restart programs. A complete list of the items of improvement found under this assessment is found in Chapter 9, along with a proposed time table for correcting remaining items that can be improved for the chemistry program of SRS reactors. An additional external review of the moderator chemistry processes, recommendations, and responses to/from the Reactor Corrosion Mitigation Committee is included as Appendix to this compilation.
ERIC Educational Resources Information Center
Owens, William A.
The author suggests that it is more efficient to cluster subjects on the basis of their profiles across several dimensions of significance and to seek "between" subgroup correlates, than to search for a moderator variable "within" levels of which criterion relationships may vary in nonrandom fashion. (Author/RK)
Simultaneous Optical Measurements of Axial and Tangential Steady-State Blade Deflections
NASA Technical Reports Server (NTRS)
Kurkov, Anatole P.; Dhadwal, Harbans S.
Currently, the majority of fiber-optic blade instrumentation is being designed and manufactured by aircraft-engine companies for their own use. The most commonly employed probe for optical blade deflection measurements is the spot probe. One of its characteristics is that the incident spot on a blade is not fixed relative to the blade, but changes depending on the blade deformation associated with centrifugal and aerodynamic loading. While there are geometrically more complicated optical probe designs in use by different engine companies, this paper offers an alternate solution derived from a probe-mount design feature that allows one to change the probe axial position until the incident spot contacts either a leading or a trailing edge. By tracing the axial position of either blade edge one is essentially extending the deflection measurement to two dimensions, axial and tangential. The blade deflection measurements were obtained during a wind tunnel test of a fan prototype.
Electric and magnetic response in dielectric dark states for low loss subwavelength optical meta atoms
Jain, Aditya; Moitra, Parikshit; Koschny, Thomas; Valentine, Jason; Soukoulis, Costas M.
Artificially created surfaces or metasurfaces, composed of appropriately shaped subwavelength structures, namely, meta-atoms, control light at subwavelength scales. Historically, metasurfaces have used radiating metallic resonators as subwavelength inclusions. However, while resonant optical metasurfaces made from metal have been sufficiently subwavelength in the propagation direction, they are too lossy for many applications. Metasurfaces made out of radiating dielectric resonators have been proposed to solve the loss problem, but are marginally subwavelength at optical frequencies. We designed subwavelength resonators made out of nonradiating dielectrics. The resonators are decorated with appropriately placed scatterers, resulting in a meta-atom with an engineered electromagnetic response. A metasurface that yields an electric response is fabricated, experimentally characterized, and a method to obtain a magnetic response at optical frequencies is theoretically demonstrated. In conclusion, this design methodology paves the way for metasurfaces that are simultaneously subwavelength and low loss.
Electric and magnetic response in dielectric dark states for low loss subwavelength optical meta atoms
Jain, Aditya; Moitra, Parikshit; Koschny, Thomas; ...
Artificially created surfaces or metasurfaces, composed of appropriately shaped subwavelength structures, namely, meta-atoms, control light at subwavelength scales. Historically, metasurfaces have used radiating metallic resonators as subwavelength inclusions. However, while resonant optical metasurfaces made from metal have been sufficiently subwavelength in the propagation direction, they are too lossy for many applications. Metasurfaces made out of radiating dielectric resonators have been proposed to solve the loss problem, but are marginally subwavelength at optical frequencies. We designed subwavelength resonators made out of nonradiating dielectrics. The resonators are decorated with appropriately placed scatterers, resulting in a meta-atom with an engineered electromagnetic response. Amore » metasurface that yields an electric response is fabricated, experimentally characterized, and a method to obtain a magnetic response at optical frequencies is theoretically demonstrated. In conclusion, this design methodology paves the way for metasurfaces that are simultaneously subwavelength and low loss.« less
Steady state and time resolved optical characterization studies of Zn2SnO4 nanowires for solar cell applications
NASA Astrophysics Data System (ADS)
Yakami, Baichhabi R.; Poudyal, Uma; Nandyala, Shashank R.; Rimal, Gaurab; Cooper, Jason K.; Zhang, Xuejie; Wang, Jing; Wang, Wenyong; Pikal, Jon M.
Nanowires are a promising option for sensitized solar cells, sensors, and display technology. Most of the work thus far has focused on binary oxides for these nanowires, but ternary oxides have advantages in additional control of optical and electronic properties. Here, we report on the diffuse reflectance, Low Temperature and Room Temperature Photoluminescence (PL), PL excitation spectrum, and Time Resolved PL (TRPL) of Zinc Tin Oxide (ZTO) nanowires grown by Chemical Vapor Deposition. The PL from the ZTO nanowires does not exhibit any band gap or near gap emission, and the diffuse reflectance measurement confirms that these ZTO nanowires have a direct forbidden transition. The broad PL spectrum reveals two Gaussian peaks centered at 1.86 eV (red) and 2.81 eV (blue), representing two distinct defect states or complexes. The PL spectra were further studied by the Time Resolved Emission Spectrum and intensity dependent PL and TRPL. The time resolved measurements show complex non-exponential decays at all wavelengths, indicative of defect to defect transitions, and the red emissive states decay much slower than the blue emissive states. The effects of annealing in air and vacuum are studied to investigate the origin of the defect states in the nanowires, showing that the blue states are related to oxygen vacancies. We propose an energy band model for the nanowires containing defect states within the band gap and the associated transitions between these states that are consistent with our measurements.
Demonstration of a solid-state optical cooler: An approach to cryogenic refrigeration
Edwards, B.C.; Anderson, J.E.; Epstein, R.I.; Mills, G.L.; Mord, A.J.
We report the successful operation of an optical cooler system. This device achieved 48&hthinsp;{degree}C of cooling from room temperature and a heat lift of 25 mW when it was pumped with 1.6 W of laser light. Its performance as a function of pump laser wavelength and chamber temperature agrees well with theoretical models. This device validates the physics needed for exploiting the laser cooling of solids to develop practical optical refrigerators. {copyright} {ital 1999 American Institute of Physics.}
A database for solid-state laser, optical, and nonlinear materials
NASA Technical Reports Server (NTRS)
Cross, P. L.; Filer, E. D.; Barnes, N. P.; Skolaut, M. W., Jr.
The database contains the physical properties of laser, optical, and nonlinear materials used by the laser models of a laser-modeling software system. The database is subdivided into two parts: spectra and tabulated data. The spectra are ASCII files of laser-material's absorption and emission spectra, and laser-diode's emission spectra. The tabulated data contains physical properties of laser, optical, and nonlinear materials, including crystalline, thermal, and mechanical properties. A menu-driven interface allows the execution from a personal directory where the user can store files containing input parameters for a specific model or the results of model's calculations.
Coherent control of population transfer between vibrational states in an optical lattice via two-path quantum interference.
Zhuang, Chao; Paul, Christopher R; Liu, Xiaoxian; Maneshi, Samansa; Cruz, Luciano S; Steinberg, Aephraim M
We demonstrate coherent control of population transfer between vibrational states in an optical lattice by using interference between a one-phonon transition at 2ω and a two-phonon transition at ω. The ω and 2ω transitions are driven by phase- and amplitude-modulation of the lattice laser beams, respectively. By varying the relative phase of these two pathways, we control the branching ratio between transitions to the first excited state and those to the higher states. Our best result shows a branching ratio of 17±2, which is the highest among coherent control experiments using analogous schemes. Such quantum control techniques may find broad application in suppressing leakage errors in a variety of quantum information architectures.
Teleportation of a Toffoli gate among distant solid-state qubits with quantum dots embedded in optical microcavities.
Hu, Shi; Cui, Wen-Xue; Wang, Dong-Yang; Bai, Cheng-Hua; Guo, Qi; Wang, Hong-Fu; Zhu, Ai-Dong; Zhang, Shou
Teleportation of unitary operations can be viewed as a quantum remote control. The remote realization of robust multiqubit logic gates among distant long-lived qubit registers is a key challenge for quantum computation and quantum information processing. Here we propose a simple and deterministic scheme for teleportation of a Toffoli gate among three spatially separated electron spin qubits in optical microcavities by using local linear optical operations, an auxiliary electron spin, two circularly-polarized entangled photon pairs, photon measurements, and classical communication. We assess the feasibility of the scheme and show that the scheme can be achieved with high average fidelity under the current technology. The scheme opens promising perspectives for constructing long-distance quantum communication and quantum computation networks with solid-state qubits.
Embedded fiber-optic sensing for accurate internal monitoring of cell state in advanced battery management systems part 2: Internal cell signals and utility for state estimation
NASA Astrophysics Data System (ADS)
Ganguli, Anurag; Saha, Bhaskar; Raghavan, Ajay; Kiesel, Peter; Arakaki, Kyle; Schuh, Andreas; Schwartz, Julian; Hegyi, Alex; Sommer, Lars Wilko; Lochbaum, Alexander; Sahu, Saroj; Alamgir, Mohamed
A key challenge hindering the mass adoption of Lithium-ion and other next-gen chemistries in advanced battery applications such as hybrid/electric vehicles (xEVs) has been management of their functional performance for more effective battery utilization and control over their life. Contemporary battery management systems (BMS) reliant on monitoring external parameters such as voltage and current to ensure safe battery operation with the required performance usually result in overdesign and inefficient use of capacity. More informative embedded sensors are desirable for internal cell state monitoring, which could provide accurate state-of-charge (SOC) and state-of-health (SOH) estimates and early failure indicators. Here we present a promising new embedded sensing option developed by our team for cell monitoring, fiber-optic (FO) sensors. High-performance large-format pouch cells with embedded FO sensors were fabricated. This second part of the paper focuses on the internal signals obtained from these FO sensors. The details of the method to isolate intercalation strain and temperature signals are discussed. Data collected under various xEV operational conditions are presented. An algorithm employing dynamic time warping and Kalman filtering was used to estimate state-of-charge with high accuracy from these internal FO signals. Their utility for high-accuracy, predictive state-of-health estimation is also explored.
Intra-night optical activity of the blazar CTA 102 during its maximum state
NASA Astrophysics Data System (ADS)
Popov, Velimir; Bachev, Rumen
CTA 102 is known to experience violent outbursts in the optical, the latest of which happened just recently (ATel #9756, ATel #9732). Following these reports we observed this object for four nights (17.11.2016 - 20.11.2016) in a search for intra-night variability.
Diffractive optics development for application on high-power solid state lasers
NASA Astrophysics Data System (ADS)
Bett, Thomas H.; Stevenson, R. M.; Taghizadeh, Mohammad R.; Miller, J. M.; Lightbody, Malcolm T. M.; Blair, Paul; Layet, Ben; Watson, Norman F.; Barton, Ian M.; Robb, Graeme; McMonagle, J.
This paper reports on the development of several diffractive optical elements (DOE) to fulfill applications on high power Nd glass laser systems. The measured performance for those components realized is discussed. These are focusing beam samplers, beam shapers, and harmonic separation filters (HSF). Designs of more demanding components operating in the resonance domain are also presented. These are linear polarizing elements and beam deflectors.
Neural network applications in automated optical inspection: state of the arts
NASA Astrophysics Data System (ADS)
Cho, Hyungsuck; Park, Won Shik
Optical inspection techniques have been widely adopted in industrial areas since they provide fast and accurate information on product quality, process status, and machine conditions. The technologies include sensing using vision, laser scattering and imaging, x-ray imaging, and other optical sensing, and data processing for classification and recognition problems. Frequently, data processing tasks are very difficult, which is mainly due to the large volume, the complexity, and the noise of the raw data acquired. Artificial neural networks have been proven to be an effective means to cope with the problems difficult to solve or inefficient to solve by convectional methodologies. This paper presents the applications of neural networks in optical inspection tasks. Among the variety of industrial areas, this paper focuses on the inspection tasks involved in printed circuit board manufacturing processes and semiconductor manufacturing processes, which are the most competing industries in the world today. In this paper, the inspection problems are addressed and the optical techniques together with neural networks to solve such problems are reviewed. The application cases to which neural networks are applied are also presented with their effects.
Moderate-power cw fibre lasers
Kurkov, Andrei S; Dianov, Evgenii M
A review of the development and investigation of moderate-power (10{sup -1}-10{sup 2} W) cw fibre lasers is presented. The properties of optical fibres doped with rare-earth ions and methods for fabricating double-clad fibres are considered. The methods for fabrication of fibre Bragg gratings used as selective reflectors are discussed and the grating properties are analysed. The main pump schemes for double-clad fibre lasers are described. The properties of fibre lasers doped with neodymium, ytterbium, erbium, thulium, and holmium ions are also considered. The principles of fabrication of Raman converters of laser radiation based on optical fibres of different compositions are discussed and the main results of their studies are presented. It is concluded that fibre lasers described in the review can produce moderate-power radiation at any wavelength in the spectral range from 0.9 to 2 {mu}m. (review)
Optical interconnects for satellite payloads: overview of the state-of-the-art
NASA Astrophysics Data System (ADS)
Vervaeke, Michael; Debaes, Christof; Van Erps, Jürgen; Karppinen, Mikko; Tanskanen, Antti; Aalto, Timo; Harjanne, Mikko; Thienpont, Hugo
The increased demand of broadband communication services like High Definition Television, Video On Demand, Triple Play, fuels the technologies to enhance the bandwidth of individual users towards service providers and hence the increase of aggregate bandwidths on terrestial networks. Optical solutions clearly leverage the bandwidth appetite easily whereas electrical interconnection schemes require an ever-increasing effort to counteract signal distortions at higher bitrates. Dense wavelength division multiplexing and all-optical signal regeneration and switching solve the bandwidth demands of network trunks. Fiber-to-the-home, and fiber-to-the-desk are trends towards providing individual users with greatly increased bandwidth. Operators in the satellite telecommunication sector face similar challenges fuelled by the same demands as for their terrestial counterparts. Moreover, the limited number of orbital positions for new satellites set the trend for an increase in payload datacommunication capacity using an ever-increasing number of complex multi-beam active antennas and a larger aggregate bandwidth. Only satellites with very large capacity, high computational density and flexible, transparent fully digital payload solutions achieve affordable communication prices. To keep pace with the bandwidth and flexibility requirements, designers have to come up with systems requiring a total digital througput of a few Tb/s resulting in a high power consuming satellite payload. An estimated 90 % of the total power consumption per chip is used for the off-chip communication lines. We have undertaken a study to assess the viability of optical datacommunication solutions to alleviate the demands regarding power consumption and aggregate bandwidth imposed on future satellite communication payloads. The review on optical interconnects given here is especially focussed on the demands of the satellite communication business and the particular environment in which the optics have
Optic-flow selective cortical sensory regions associated with self-reported states of vection
Uesaki, Maiko; Ashida, Hiroshi
Optic flow is one of the most important visual cues to the estimation of self-motion. It has repeatedly been demonstrated that a cortical network including visual, multisensory, and vestibular areas is implicated in processing optic flow; namely, visual areas middle temporal cortex (MT+), V6; multisensory areas ventral intra-parietal area (VIP), cingulate sulcus visual area, precuneus motion area (PcM); and vestibular areas parieto-insular vestibular cortex (PIVC) and putative area 2v (p2v). However, few studies have investigated the roles of and interaction between the optic-flow selective sensory areas within the context of self-motion perception. When visual information (i.e., optic flow) is the sole cue to computing self-motion parameters, the discrepancy amongst the sensory signals may induce an illusion of self-motion referred to as 'vection.' This study aimed to identify optic-flow selective sensory areas that are involved in the processing of visual cues to self-motion, by introducing vection as an index and assessing activation in which of those areas reflect vection, using functional magnetic resonance imaging. The results showed that activity in visual areas MT+ and V6, multisensory area VIP and vestibular area PIVC was significantly greater while participants were experiencing vection, as compared to when they were experiencing no vection, which may indicate that activation in MT+, V6, VIP, and PIVC reflects vection. The results also place VIP in a good position to integrate visual cues related to self-motion and vestibular information. PMID:26106350
Frequency analysis of the visual steady-state response measured with the fast optical signal in younger and older adults
Tse, Chun-Yu; Gordon, Brian A.; Fabiani, Monica; Gratton, Gabriele
Relatively high frequency activity (>4 Hz) carries important information about the state of the brain or its response to high frequency events. The electroencephalogram (EEG) is commonly used to study these changes because it possesses high temporal resolution and a good signal-to-noise ratio. However, it provides limited spatial information. Non-invasive fast optical signals (FOS) have been proposed as a neuroimaging tool combining spatial and temporal resolution. Yet, this technique has not been applied to study high frequency brain oscillations because of its relatively low signal-to-noise ratio. Here we investigate the sensitivity of FOS to relatively high-frequency brain oscillations. We measured the steady-state optical response elicited in medial and lateral occipital cortex by checkerboard reversals occurring at 4, 6, and 8 Hz in younger and older adults. Stimulus-dependent oscillations were observed at the predicted stimulation frequency. In addition, in the younger adults the FOS steady-state response was smaller in lateral than medial areas, whereas in the older adults it was reversed in these two cortical regions. This may reflect diminished top-down inhibitory control in the older adults. The results indicate that FOS can be used to study the modulation of relatively high-frequency brain oscillations in adjacent cortical regions. PMID:20566389
Schemes generating entangled states and entanglement swapping between photons and three-level atoms inside optical cavities for quantum communication
NASA Astrophysics Data System (ADS)
Heo, Jino; Kang, Min-Sung; Hong, Chang-Ho; Yang, Hyeon; Choi, Seong-Gon
We propose quantum information processing schemes based on cavity quantum electrodynamics (QED) for quantum communication. First, to generate entangled states (Bell and Greenberger-Horne-Zeilinger [GHZ] states) between flying photons and three-level atoms inside optical cavities, we utilize a controlled phase flip (CPF) gate that can be implemented via cavity QED). Subsequently, we present an entanglement swapping scheme that can be realized using single-qubit measurements and CPF gates via optical cavities. These schemes can be directly applied to construct an entanglement channel for a communication system between two users. Consequently, it is possible for the trust center, having quantum nodes, to accomplish the linked channel (entanglement channel) between the two separate long-distance users via the distribution of Bell states and entanglement swapping. Furthermore, in our schemes, the main physical component is the CPF gate between the photons and the three-level atoms in cavity QED, which is feasible in practice. Thus, our schemes can be experimentally realized with current technology.
Multi-metastable states induced by the optical pump-probe process in terahertz quantum cascade lasers
Wang, F.; Guo, X. G. Wang, C.; Cao, J. C.
The optical pump-probe process in terahertz quantum cascade lasers is studied theoretically by using the open system simulation method. The emitter injection is considered and the charge neutrality in the active region is broken. We find that nonequilibrium oscillations may appear in the recovery processes. In particular, the formation of different equilibrium values of the population change after the periodic pulse pumping is observed clearly. Here, the phenomenon of multi-metastable states stems from the electron regulation by the emitter injection. Finally, we discuss the important impacts of the equilibrium stabilization time and obtain an in-depth understanding of the emitter injection.
Kilohertz generation of high contrast polarization states for visible femtosecond pulses via phase-locked acousto-optic pulse shapers
Seiler, Hélène; Walsh, Brenna; Palato, Samuel; Kambhampati, Patanjali; Thai, Alexandre; Forget, Nicolas; Crozatier, Vincent
We present a detailed analysis of a setup capable of arbitrary amplitude, phase, and polarization shaping of broadband visible femtosecond pulses at 1 kHz via a pair of actively phase stabilized acousto-optic programmable dispersive filters arranged in a Mach-Zehnder interferometer geometry. The setup features phase stability values around λ/225 at 580 nm as well as degrees of polarization of at least 0.9 for any polarization state. Both numbers are important metrics to evaluate a setup's potential for applications based on polarization-shaped femtosecond pulses, such as fully coherent multi-dimensional electronic spectroscopy.
Calculation of eta-meson-nucleus quasibound states with optical potentials of the square-well and woods-saxon forms
Tryasuchev, V. A.; Isaev, A. V.
The results obtained by calculating bound states of eta mesons and nuclei by using a squarewell optical potential are compared with their counterparts based on the use of an optical potential in the Woods-Saxon form. For any reasonable choice of range for a potential that has a sharp boundary, the results for the case of a diffuse boundary demonstrate the need for a greater baryon charge in order that an eta meson form a bound state with nuclei. The dependence of the probability for the formation of etamesonic nuclei on the diffuseness parameter of the optical potential involving the Woods-Saxon radial dependence is revealed.
Improved ground-state electronic structure and optical dielectric constants with a semilocal exchange functional
NASA Astrophysics Data System (ADS)
Vlček, Vojtěch; Steinle-Neumann, Gerd; Leppert, Linn; Armiento, Rickard; Kümmel, Stephan
A recently published generalized gradient approximation functional within density functional theory (DFT) has shown, in a few paradigm tests, an improved KS orbital description over standard (semi)local approximations. The characteristic feature of this functional is an enhancement factor that diverges like s ln(s ) for large reduced density gradients s which leads to unusual properties. We explore the improved orbital description of this functional more thoroughly by computing the electronic band structure, band gaps, and the optical dielectric constants in semiconductors, Mott insulators, and ionic crystals. Compared to standard semilocal functionals, we observe improvement in both the band gaps and the optical dielectric constants. In particular, the results are similar to those obtained with orbital functionals or by perturbation theory methods in that it opens band gaps in systems described as metallic by standard (semi)local density functionals, e.g., Ge, α -Sn, and CdO.
Topological states in a ladder-like optical lattice containing ultracold atoms in higher orbital bands
NASA Astrophysics Data System (ADS)
Li, Xiaopeng; Zhao, Erhai; Vincent Liu, W.
Topological insulators are classified according to their symmetries. Discovery of them in electronic solids is thus restricted by orbital and crystalline symmetries available in nature. Synthetic quantum matter, such as the recent double-well optical lattices loaded with s and p orbital ultracold atoms, can exploit symmetries and interaction beyond natural conditions. Here we unveil a topological phase of interacting fermionic atoms on a two-leg ladder derived from the above experimental optical lattice by dimension reduction. The topological band structure originates from the staggered phases of sp orbital tunnelling, requiring neither spin-orbit coupling nor other known mechanisms like p-wave pairing, artificial gauge field or rotation. Upon crossing over to two-dimensional coupled ladders, the edge modes from individual ladder form a parity-protected flat band at zero energy. Experimental signatures are found in density correlations and phase transitions to trivial band and Mott insulators.
Photon-number entangled states generated in Kerr media with optical parametric pumping
Kowalewska-Kudlaszyk, A.; Leonski, W.; Perina, Jan Jr.
Two nonlinear Kerr oscillators mutually coupled by parametric pumping are studied as a source of states entangled in photon numbers. Temporal evolution of entanglement quantified by negativity shows the effects of sudden death and birth of entanglement. Entanglement is preserved even in asymptotic states under certain conditions. The role of reservoirs at finite temperature in entanglement evolution is elucidated. Relation between generation of entangled states and violation of Cauchy-Schwartz inequality for oscillator intensities is found.
Barium boron aluminum silicate glass system for solid state optical gas sensors
NASA Astrophysics Data System (ADS)
Da Silva, M. J.; Karczewski, J.; Jasinski, P.; Chrzan, A.; Kalinowski, P.; Szymczewska, D.; Jasinski, G.
Recent increasing demand for new eco-friendly materials and for low cost fabrication process for use in optical sensors field, raise concern about alternative materials for this application. We have designed two glass-ceramics compositions from the quaternary ROAl2O3- SiO2-B2O3(R=Ba) alkali-earth aluminum silicate system, labeled B72 and B69, with high refractive index (>1.6), large values of Abbe number (94.0 and 53.0, respectively), and free of lead and arsenic. We present an analysis and discussion of experimental optical properties, thermal and thermo-chemical stability along with important properties such as transition temperature (Tg), onset of crystallization (Tx) as well transport properties as ionic conductivity behavior in the quaternary glass-ceramic system containing boron for use as optical sensors. Complex Impedance Spectra (Bode Plot) and Potentiodynamic Polarization curves (Tafel plots) measurements were carried out in the temperature range of 600 to 850°C. The most probable conductivity mechanism is a thermally activated process of mobile ions overcoming a potential barrier (EA), according to the Arrhenius regime. Here we report that charge transfer is caused by the flux of electrons, in the region of elevated temperatures (>700°C), and is affected by immiscibility of crystals, nucleation and growth type, that causes phase separation. We found conductivity (σ) values from 10-9 to 10-5 S/cm at temperatures between 700 and 850°C. Our results highlight a need for research on ion mobility in the glassy network above the transition range, and the effect cause by metastable immiscibility in the alkaline-earth glasses are exposed. The two glass compositions B72 and B69 can be tailored by proper use as glassy optical sensor.
Ionic two photon states and optical nonlinearity in. pi. -conjugated polymers
Dixit, S.N. ); Guo, D.; Mazumdar, S. . Dept. of Physics)
A microscopic mechanism of optical nonlinearity in {pi}-conjugated polymers is presented. It is shown that the bulk of the nonlinearity is determined by only two well defined channels, even though an infinite number of channels are possible in principle. The above conclusion is true for both short and long range Coulomb interactions. The complete frequency dependence of the third harmonic generation in both trans-polyacetylene and polydiacetylene are explained within the same theoretical picture. 19 refs., 4 figs.
Two-state vs. multistate protein unfolding studied by optical melting and hydrogen exchange.
Mayne, L.; Englander, S. W.
A direct conflict between the stabilization free energy parameters of cytochrome c determined by optical methods and by hydrogen exchange (HX) is quantitatively explained when the partially folded intermediates seen by HX are taken into account. The results support the previous HX measurements of intermediate populations, show how intermediates can elude the standard melting analysis, and illustrate how they confuse the analysis when they are significantly populated within the melting transition region. PMID:11106159
Structure of multiphoton quantum optics. II. Bipartite systems, physical processes, and heterodyne squeezed states
NASA Astrophysics Data System (ADS)
dell'Anno, Fabio; de Siena, Silvio; Illuminati, Fabrizio
Extending the scheme developed for a single mode of the electromagnetic field in the preceding paper [
Structure of multiphoton quantum optics. II. Bipartite systems, physical processes, and heterodyne squeezed states
Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio
Extending the scheme developed for a single mode of the electromagnetic field in the preceding paper [F. Dell'Anno, S. De Siena, and F. Illuminati, Phys. Rev. A 69, 033812 (2004)], we introduce two-mode nonlinear canonical transformations depending on two heterodyne mixing angles. They are defined in terms of Hermitian nonlinear functions that realize heterodyne superpositions of conjugate quadratures of bipartite systems. The canonical transformations diagonalize a class of Hamiltonians describing nondegenerate and degenerate multiphoton processes. We determine the coherent states associated with the canonical transformations, which generalize the nondegenerate two-photon squeezed states. Such heterodyne multiphoton squeezed states are defined as the simultaneous eigenstates of the transformed, coupled annihilation operators. They are generated by nonlinear unitary evolutions acting on two-mode squeezed states. They are non-Gaussian, highly nonclassical, entangled states. For a quadratic nonlinearity the heterodyne multiphoton squeezed states define two-mode cubic phase states. The statistical properties of these states can be widely adjusted by tuning the heterodyne mixing angles, the phases of the nonlinear couplings, as well as the strength of the nonlinearity. For quadratic nonlinearity, we study the higher-order contributions to the susceptibility in nonlinear media and we suggest possible experimental realizations of multiphoton conversion processes generating the cubic-phase heterodyne squeezed states.
An adaptive optics system for solid-state laser systems used in inertial confinement fusion
Salmon, J.T.; Bliss, E.S.; Byrd, J.L.; Feldman, M.; Kartz, M.A.; Toeppen, J.S.; Wonterghem, B. Van; Winters, S.E.
Using adaptive optics the authors have obtained nearly diffraction-limited 5 kJ, 3 nsec output pulses at 1.053 {micro}m from the Beamlet demonstration system for the National Ignition Facility (NIF). The peak Strehl ratio was improved from 0.009 to 0.50, as estimated from measured wavefront errors. They have also measured the relaxation of the thermally induced aberrations in the main beam line over a period of 4.5 hours. Peak-to-valley aberrations range from 6.8 waves at 1.053 {micro}m within 30 minutes after a full system shot to 3.9 waves after 4.5 hours. The adaptive optics system must have enough range to correct accumulated thermal aberrations from several shots in addition to the immediate shot-induced error. Accumulated wavefront errors in the beam line will affect both the design of the adaptive optics system for NIF and the performance of that system.
State-of-the art of acousto-optic sensing and imaging of turbid media.
Resink, Steffen G; Boccara, Albert C; Steenbergen, Wiendelt
Acousto-optic (AO) is an emerging hybrid technique for measuring optical contrast in turbid media using coherent light and ultrasound (US). A turbid object is illuminated with a coherent light source leading to speckle formation in the remitted light. With the use of US, a small volume is selected,which is commonly referred to as the "tagging" volume. This volume acts as a source of modulated light, where modulation might involve phase and intensity change. The tagging volume is created by focusing ultrasound for good lateral resolution; the axial resolution is accomplished by making either the US frequency, amplitude, or phase time-dependent. Typical resolutions are in the order of 1 mm. We will concentrate on the progress in the field since 2003. Different schemes will be discussed to detect the modulated photons based on speckle detection, heterodyne detection, photorefractive crystal (PRC) assisted detection, and spectral hole burning (SHB) as well as Fabry-Perot interferometers. The SHB and Fabry-Perot interferometer techniques are insensitive to speckle decorrelation and therefore suitable for in vivo imaging. However, heterodyne and PRC methods also have potential for in vivo measurements. Besides measuring optical properties such as scattering and absorption, AO can be applied in fluorescence and elastography applications.
Probe spectroscopy in an operating magneto-optical trap: The role of Raman transitions between discrete and continuum atomic states
Brzozowski, Tomasz M.; Brzozowska, Maria; Zachorowski, Jerzy; Zawada, Michal; Gawlik, Wojciech
We report on cw measurements of probe beam absorption and four-wave-mixing spectra in a {sup 85}Rb magneto-optical trap taken while the trap is in operation. The trapping beams are used as pump light. We concentrate on the central feature of the spectra at small pump-probe detuning and attribute its narrow resonant structures to the superposition of Raman transitions between light-shifted sublevels of the ground atomic state and to atomic recoil processes. These two contributions have different dependencies on trap parameters and we show that the former is inhomogeneously broadened. The strong dependence of the spectra on the probe-beam polarization indicates the existence of large optical anisotropy of the cold-atom sample, which is attributed to the recoil effects. We point out that the recoil-induced resonances can be isolated from other contributions, making pump-probe spectroscopy a highly sensitive diagnostic tool for atoms in a working magneto-optical trap.
Magneto-dielectric effects induced by optically-generated intermolecular charge-transfer states in organic semiconducting materials.
Zang, Huidong; Yan, Liang; Li, Mingxing; He, Lei; Gai, Zheng; Ivanov, Ilia; Wang, Min; Chiang, Long; Urbas, Augustine; Hu, Bin
Traditionally, magneto-dielectric effects have been developed by combining ferroelectric and magnetic materials. Here, we show a magneto-dielectric effect from optically-generated intermolecular charge-transfer states in an organic semiconducting donor:acceptor (PVK:TCNB) system. We observe in magnetic field effects of photoluminescence that a magnetic field can change singlet/triplet population ratio in intermolecular charge-transfer states. Furthermore, our theoretical analysis and experimental evidence indicate that the singlets and triplets in charge-transfer states have stronger and weaker electrical polarizations, respectively. Therefore, the observed magneto-dielectric effect can be attributed to magnetically-dependent singlet/triplet ratio in intermolecular charge-transfer states. In principle, a magneto-dielectric effect can be generated through two different channels based on magneto-polarization and magneto-current effects when the singlet/triplet ratio in intermolecular charge-transfer states is changed by a magnetic field. We find, from the simulation of dielectric effects, that magneto-polarization and magneto-current effects play primary and secondary roles in the generation of magneto-dielectric effect.
Optical Properties of Iridium(III) Cyclometalates: Excited State Interaction with Small Molecules and Dynamics of Light-Harvesting Materials
NASA Astrophysics Data System (ADS)
Schwartz, Kyle Robert
The research presented in this thesis concerns the use and understanding of luminescent Ir(III) cyclometalates. Areas of research involve the design, synthesis, and characterization of novel luminescent Ir(III) cyclometalates, including photophysical investigation of their phosphorescent excited states using steady-state and time resolved absorption/luminescence spectroscopies. This broad research description may be further separated into two subareas: study of excited state interaction with small molecules and excited-state dynamics of metal-organic light harvesting dyads. Interaction of Ir(III) cyclometalates with the small molecule carbon dioxide (CO2) is the subject of Chapter One. Most optical detection schemes previously developed for CO2 use indirect detection methods, which rely upon measuring changes in pH brought about by hydrolysis of CO 2 on of CO2 were accomplished through development of a system where hydrazine, a simple amino ligand, when coupled into the coordination sphere of an Ir(III) cyclometalate reacts with CO2. The result of this reaction provides a shift in the luminescence wavelength, a previously unobserved optical response for CO2 detection. Chapter Two investigates phosphorescent excited states and their ability to function as triplet sensitizers for the generation of singlet oxygen ( 1O2) and luminescent probes for molecular oxygen (O 2) concentration. Interaction of phosphorescent excited states with O2 results in energy transfer from the luminescent probe to O 2, quenching the phosphorescent excited state. Energy transfer also generates the reactive oxygen species (ROS) 1O2. We have used this duality to develop an analytical methodology to follow the serendipitously discovered photoreactivity of 1O2 with common organic solvent dimethyl sulfoxide (DMSO) using the luminescence profile of Ir(III) and Ru(II) phosphors. In Chapter Three a detailed study involving the design, synthesis, and characterization of the electrochemical and
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: On Superconductivity State in Pure Graphene
NASA Astrophysics Data System (ADS)
Mousavi, Hamze
We study theoretically the possibility of superconductivity state in pure graphene within the extended attractive Hubbard model. In the absence of disorder, when we use the local attractive interaction potential, U ⋍ 5t, where t is hopping term, pure graphene can be in superconductivity state.
Linear-optical simulation of the cooling of a cluster-state Hamiltonian system.
Aguilar, G H; Kolb, T; Cavalcanti, D; Aolita, L; Chaves, R; Walborn, S P; Souto Ribeiro, P H
A measurement-based quantum computer could consist of a local-gapped Hamiltonian system, whose thermal states-at sufficiently low temperature-are universal resources for the computation. Initialization of the computer would correspond to cooling the system. We perform an experimental quantum simulation of such a cooling process with entangled photons. We prepare three-qubit thermal cluster states exploiting the equivalence between local dephasing and thermalization for these states. This allows us to tune the system's temperature by changing the dephasing strength. We monitor the entanglement as the system cools down and observe the transitions from separability to bound entanglement, and then to free entanglement. We also analyze the performance of the system for measurement-based single-qubit state preparation. These studies constitute a basic characterization of experimental cluster-state computation under imperfect conditions.
IRIA State-of-the-Art Report: Optical-Mechanical, Active/Passive Imaging Systems. Volume I.
J. Klein, " Optical Antenna Gain 2: Receiving Antennas", Applied Optics, Optical Society of America, Washington, DC, Volume 13, 1974.7 149 ~RIM V...Fourier Optics, McGraw-Hill, New York, NY, 1968. 227 SRIM [2-18] J. J. Degnan and B. J. Klein, " Optical Antenna Gain 2: Receiving Antennas" A lied Optics...and B. J. Klein, " Optical Antenna Gain 2: Receiving Antennas", Applied Optics, Optical Society of America, Washington, DC, Volume 13, 1974, pp.2397
A three-dimensional sectional representation of aerosol mixing state for simulating optical properties and cloud condensation nuclei
Ching, Ping Pui; Zaveri, Rahul A.; Easter, Richard C.; Riemer, Nicole; Fast, Jerome D.
Light absorption by black carbon (BC) particles emitted from fossil fuel combustion depends on the how thickly they are coated with non-refractory species such as ammonium, sulfate, nitrate, organics, and water. The cloud condensation nuclei (CCN) activation property of a particle depends on its dry size and the hygroscopicities of all the individual species mixed together. It is therefore necessary to represent both size and mixing state of aerosols to reliably predict their climate-relevant properties in atmospheric models. Here we describe and evaluate a novel sectional framework in the Model for Simulating Aerosol Interactions and Chemistry, referred to as MOSAIC-mix, that represents the mixing state by resolving aerosol dry size (Ddry), BC dry mass fraction (wBC), and hygroscopicity (κ). Using ten idealized urban plume scenarios in which different types of aerosols evolve over 24 hours under a range of atmospherically relevant environmental conditions, we examine errors in CCN concentrations and optical properties with respect to a more explicit aerosol mixing state representation. We find that only a small number of wBC and κ bins are needed to achieve significant reductions in the errors, and propose a configuration consisting of 24 Ddry bins, 2 wBC bins, and 2 κ bins that gives 24-hour average errors of about 5% or less in CCN concentrations and optical properties, 3-4 times lower than those from size-only-resolved simulations. These results show that MOSAIC-mix is suitable for use in regional and global models to examine the effects of evolving aerosol mixing states on aerosol-radiation-cloud feedbacks.
In-situ measurements of the mixing state and optical properties of soot with implications for radiative forcing estimates
Moffet, Ryan C.; Prather, Kimberly A.
Our ability to predict how global temperatures will change in the future is currently limited by the large uncertainties associated with aerosols. Soot aerosols represent a major research focus as they influence climate by absorbing incoming solar radiation resulting in a highly uncertain warming effect. The uncertainty stems from the fact that the actual amount soot warms our atmosphere strongly depends on the manner and degree in which it is mixed with other species, a property referred to as mixing state. In global models and inferences from atmospheric heating measurements, soot radiative forcing estimates currently differ by a factor of 6, ranging between 0.2–1.2 W/m2, making soot second only to CO2 in terms of global warming potential. This article reports coupled in situ measurements of the size-resolved mixing state, optical properties, and aging timescales for soot particles. Fresh fractal soot particles dominate the measured absorption during peak traffic periods (6–9 AM local time). Immediately after sunrise, soot particles begin to age by developing a coating of secondary species including sulfate, ammonium, organics, nitrate, and water. Based on these direct measurements, the core-shell arrangement results in a maximum absorption enhancement of 1.6× over fresh soot. These atmospheric observations help explain the larger values for soot forcing measured by others and will be used to obtain closure in optical property measurements to reduce one of the largest remaining uncertainties in climate change. PMID:19581581
Effect of aggregation, morphology and mixing state on optical properties of bare and internally mixed Black Carbon particles
NASA Astrophysics Data System (ADS)
Scarnato, Barbara; China, Swarup; Mazzoleni, Claudio
Black carbon (BC) is a small, dark particle that warms Earth's climate. BC is a distinct type of carbonaceous aerosol particle, product of combustion of fossil and biomass fuels. Upon emission into the atmosphere, BC internally mixes with other aerosol compounds. According to recent studies, internal mixing of BC with other aerosol materials in the atmosphere alters its aggregate shape, absorption of solar radiation, and radiative forcing. These mixing state effects are not yet fully understood. Laboratory and field studies have identified a strong variability in the observed absorption efficiencies of internally mixed BC. Additionally, there is a discrepancy between modeled and measured values using traditional modeling approaches. This talk will investigate the central role of parameterization of light interaction by BC particles in the assessment of its radiative forcing and present a sensitivity study of the effect of aggregation, morphology and mixing state on optical properties of bare and internally mixed BC with mineral dust, ammonium sulfate, sodium chloride and others. Optical properties of the different mixtures, sampled both in field campaigns and laboratory environment, are computed using Discrete Dipole Approximation model in accordance with BC aggregation, morphology and mixing observed at microscopes. The results of this work are relevant for several applications in atmospheric science, including but not limited to radiative transfer calculations, regional and global climate modeling and, the interpretation of remote sensing measurements.
Structure of a LOV protein in apo-state and implications for construction of LOV-based optical tools
Arinkin, Vladimir; Granzin, Joachim; Röllen, Katrin; Krauss, Ulrich; Jaeger, Karl-Erich; Willbold, Dieter; Batra-Safferling, Renu
Unique features of Light-Oxygen-Voltage (LOV) proteins like relatively small size (~12–19 kDa), inherent modularity, highly-tunable photocycle and oxygen-independent fluorescence have lately been exploited for the generation of optical tools. Structures of LOV domains reported so far contain a flavin chromophore per protein molecule. Here we report two new findings on the short LOV protein W619_1-LOV from Pseudomonas putida. First, the apo-state crystal structure of W619_1-LOV at 2.5 Å resolution reveals conformational rearrangements in the secondary structure elements lining the chromophore pocket including elongation of the Fα helix, shortening of the Eα-Fα loop and partial unfolding of the Eα helix. Second, the apo W619_1-LOV protein binds both natural and structurally modified flavin chromophores. Remarkably different photophysical and photochemical properties of W619_1-LOV bound to 7-methyl-8-chloro-riboflavin (8-Cl-RF) and lumichrome imply application of these variants as novel optical tools as they offer advantages such as no adduct state formation, and a broader choice of wavelengths for in vitro studies. PMID:28211532
Refined entanglement concentration for electron-spin entangled cluster states with quantum-dot spins in optical microcavities
NASA Astrophysics Data System (ADS)
Du, Fang-Fang; Long, Gui-Lu
We present a refined entanglement concentration protocol (ECP) for an arbitrary unknown less-entangled four-electron-spin cluster state by exploring the optical selection rules derived from the quantum-dot spins in one-sided optical microcavities. In our ECP, the parties obtain not only the four-electron-spin systems in the partial entanglement with two unknown parameters, but also the less-entangled two-electron-spin systems in the first step. Utilizing the above preserved systems as the resource for the second step of our ECP, the parties can obtain a standard cluster state by keeping the robust odd-parity instances with two parity-check gates. Meanwhile, the systems in the rest three instances can be used as the resource in the next round of our ECP. The success probability of our ECP is largely increased by iteration of the ECP process. Moreover, all the coefficients of our ECP are unknown for the parties without assistance of extra single electron-spin, so our ECP maybe has good applications in quantum communication network in the future.
The case for moderate gun control.
DeGrazia, David
In addressing the shape of appropriate gun policy, this essay assumes for the sake of discussion that there is a legal and moral right to private gun ownership. My thesis is that, against the background of this right, the most defensible policy approach in the United States would feature moderate gun control. The first section summarizes the American gun control status quo and characterizes what I call "moderate gun control." The next section states and rebuts six leading arguments against this general approach to gun policy. The section that follows presents a positive case for moderate gun control that emphasizes safety in the home and society as well as rights whose enforcement entails some limits or qualifications on the right to bear arms. A final section shows how the recommended gun regulations address legitimate purposes, rather than imposing arbitrary restrictions on gun rights, and offers concluding reflections.
All-optical digital logic: Full addition or subtraction on a three-state system
Remacle, F.; Levine, R. D.
Stimulated Raman adiabatic passage (STIRAP) is a well-studied pump-probe control scheme for manipulating the population of quantum states of atoms or molecules. By encoding the digits to be operated on as 'on' or 'off' laser input signals we show how STIRAP can be used to implement a finite-state logic machine. The physical conditions required for an effective STIRAP operation are related to the physical conditions expected for a logic machine. In particular, a condition is derived on the mean number of photons that represent an on pulse. A finite-state machine computes Boolean expressions that depend both on the input and on the present state of the machine. With two input signals we show how to implement a full adder where the carry-in digit is stored in the state of the machine. Furthermore, we show that it is possible to store the carry-out digit as the next state and thereby return the machine to a state ready for the next full addition. Such a machine operates as a cyclical full adder. We further show how this full adder can equally well be operated as a full subtractor. To the best of our knowledge this is the first example of a nanosized system that implements a full subtraction.
Quantum State Reduction by Matter-Phase-Related Measurements in Optical Lattices.
Kozlowski, Wojciech; Caballero-Benitez, Santiago F; Mekhov, Igor B
A many-body atomic system coupled to quantized light is subject to weak measurement. Instead of coupling light to the on-site density, we consider the quantum backaction due to the measurement of matter-phase-related variables such as global phase coherence. We show how this unconventional approach opens up new opportunities to affect system evolution. We demonstrate how this can lead to a new class of final states different from those possible with dissipative state preparation or conventional projective measurements. These states are characterised by a combination of Hamiltonian and measurement properties thus extending the measurement postulate for the case of strong competition with the system's own evolution.
Electron and optical properties of fullerene C70 within the conception of a strongly correlated state
NASA Astrophysics Data System (ADS)
Lobanov, B. V.; Murzashev, A. I.
In the framework of the Hubbard model in the static fluctuation approximation, the energy spectrum of fullerene C70 with allowance for different lengths of the bonds between nonequivalent nodes is calculated. On the basis of the calculated energy spectrum, the optical absorption spectrum in the ultraviolet and visible region is simulated. A good qualitative agreement between the calculated and measured absorption spectra and between the measured and theoretical values of the gap width between the highest occupied and the lowest unoccupied molecular orbital is found.
State-of-the-art optical fiber ends: fabrication and application
NASA Astrophysics Data System (ADS)
Yuan, Libo
State-of-the-art of bare fiber end polishing techniques are introduced and demonstrated. It is essential for many applications such as in low loss, high bit rate communication system and special requirement for fiber sensing probe.
Tuning the Optically Bright and Dark States of Doped Graphene Quantum Dots
NASA Astrophysics Data System (ADS)
Mukhopadhyay, Madhuri; Pandey, Bradraj; Pati, Swapan K.
Employing a combination of the many-body configuration-interaction method described by an extended Hubbard model and first-principles calculations, we predict the emergence of high oscillator strength at the near-IR region which originates from the Davydov type of splitting in doped graphene quantum dots (GQDs). Incorporation of the strain in GQDs promotes closely spaced bright states that are pertinent to coherent excitation. Controlling the destructive interference of the functionalized-nanographene quantum states, the dark states can be tuned towards the red end, ensuring that the system is a good candidate for a photocell. On the other hand, the coherent states can be tailored to concentrate the light at a very high intensity, resulting in an opportunity for a photonic device.
Optical properties of solid-state laser type materials in the near IR
NASA Astrophysics Data System (ADS)
Brenier, Alain; Garapon, Claudine; Madej, Christine; Moine, Bernard; Moncorge, Richard; Monteil, Andre; Pedrini, Christian; Boulon, Georges
Work being done on solid-state lasers in a single laboratory is reviewed. Recent results on broadly tunable laser systems based on transition metal ions are addressed, discussing excited-state absorption measurements and the search for new emitting centers. The main emission spectra obtained with the rare earth doped laser materials Nd(3+), Er(3+), Tm(3+), and Ho(3+) are shown and discussed.
Solid State Imaging Device Parameter Study for Use in Electro-Optic Tracking Systems.
DRAWER DE NUCLEAR ENGINEERING MISSISSIPPI STATE UNIVERSITY ELDRED W. HOUGH, PH.D. MISSISSIPPI STATE, MISSISSIPPI 39762 PETROLEUM ENGINEERING TELEPHONE...are available for investigation. Both utilize the same tracking algorithm, but have different detector arrays. Tracker Number 1 uses a Reticon 50 x 50 A...encoding the outputs of linear reticon arrays. lTese I encoded dataare available then for instant recall. Up to 30 to 1 reductions of such information
Measurement of solid-state optical refrigeration by two-band differential luminescence thermometry
Hehlen, Markus P; Epstein, Richard I; Patterson, Wendy M; Sheik - Bahae, Mansoor; Seletskiy, D V
We present a non-contact spectroscopic teclmique for the measurement of laser-induced temperature changes in solids. Two-band differential luminescence thermometry (TBDLT) achieves a sensitivity of {approx}7 mK and enables precise measurement of the net quantum efficiency of optical refrigerator materials. TBDLT detects internal temperature changes by decoupling surface and bulk heating effects via time-resolved luminescence spectroscopy. Several Yb{sup 3+}-doped fluorozirconate (ZBLANI) glasses fabricated from precursors of varying purity and by different processes are analyzed in detail. A net quantum efficiency of 97.39% at 238 K (at a pump wavelength of 1020.5 nm) is found for a ZBLANI:1%Yb{sup 3+} laser-cooling sample produced from metal fluoride precursors that were purified by chelate-assisted solvent extraction and dried in hydrofluoric gas. In comparison, a ZBLANI:1%Yb{sup 3+} sample produced from commercial-grade metal fluoride precursors showed pronounced laser-induced heating that is indicative of a substantially higher impurity concentration. TBDLT enables rapid and sensitive benchmarking of laser-cooling materials and provides critical feedback to the development and optimization of high-performance optical cryocooler materials.
2013 Apparition of Near-Earth Asteroid (52760) 1998 ML14: Radar and Optical Constraints on Shape and Spin State
NASA Astrophysics Data System (ADS)
Sharkey, Benjamin N. L.; Taylor, Patrick A.; Nolan, Michael C.; Howell, Ellen S.; Benner, Lance A. M.
Radar images taken by the Arecibo and Goldstone planetary radar systems in 1998 were used by Ostro et al. (Meteoritics & Planetary Science, 36, 1225-1236, 2001) to produce a shape model of the approximately 1-km diameter near-Earth asteroid (52760) 1998 ML14; however, the spin state (pole orientation and rotation period) was not well determined in their modeling. The published shape model was produced using a 14.83 h sidereal rotation period, consistent with the synodic period of 14.98 ± 0.06 h found by optical observations in 1998 (Hicks & Weissman, IAU Circular 6987, 1, 1998). Optical observations in 2013 found a faster synodic period of 14.28 ± 0.01 h (Warner, The Minor Planet Bulletin, 41, 2, 113-124, 2014). Further radar observations at Arecibo in 2013 are inconsistent with the 14.83 h sidereal period. Use of Arecibo radar images from both apparitions, with resolution as fine as 15 m per pixel, are best fit by a sidereal period within 1% of 14.28 h and constrain the pole orientation to within approximately ten degrees. This period is consistent with all radar and lightcurve data. An updated shape model, combining all known observations, will be presented in light of the constraints on ML14's spin state. The model suggests the presence of several smaller topographic features not previously seen, but remains consistent with major features of the previously published model (notably a distinctive saddle-like region).This improved model illustrates the power of multiple radar apparitions for better determining the true shapes and spin states of near-Earth asteroids, as well as the benefits of multiple observers operating at different wavelength regimes.
High-intensity interval training versus moderate-intensity steady-state training in UK cardiac rehabilitation programmes (HIIT or MISS UK): study protocol for a multicentre randomised controlled trial and economic evaluation
McGregor, Gordon; Nichols, Simon; Hamborg, Thomas; Bryning, Lucy; Tudor-Edwards, Rhiannon; Markland, David; Mercer, Jenny; Birkett, Stefan; Ennis, Stuart; Powell, Richard; Begg, Brian; Haykowsky, Mark J; Banerjee, Prithwish; Ingle, Lee; Shave, Rob; Backx, Karianne
Introduction Current international guidelines for cardiac rehabilitation (CR) advocate moderate-intensity exercise training (MISS, moderate-intensity steady state). This recommendation predates significant advances in medical therapy for coronary heart disease (CHD) and may not be the most appropriate strategy for the 'modern' patient with CHD. High-intensity interval training (HIIT) appears to be a safe and effective alternative, resulting in greater improvements in peak oxygen uptake (VO2 peak). To date, HIIT trials have predominantly been proof-of-concept studies in the laboratory setting and conducted outside the UK. The purpose of this multicentre randomised controlled trial is to compare the effects of HIIT and MISS training in patients with CHD attending UK CR programmes. Methods and analysis This pragmatic study will randomly allocate 510 patients with CHD to 8 weeks of twice weekly HIIT or MISS training at 3 centres in the UK. HIIT will consist of 10 high-intensity (85–90% peak power output (PPO)) and 10 low-intensity (20–25% PPO) intervals, each lasting 1 min. MISS training will follow usual care recommendations, adhering to currently accepted UK guidelines (ie, >20 min continuous exercise at 40–70% heart rate reserve). Outcome measures will be assessed at baseline, 8 weeks and 12 months. The primary outcome for the trial will be change in VO2 peak as determined by maximal cardiopulmonary exercise testing. Secondary measures will assess physiological, psychosocial and economic outcomes. Ethics and dissemination The study protocol V.1.0, dated 1 February 2016, was approved by the NHS Health Research Authority, East Midlands—Leicester South Research Ethics Committee (16/EM/0079). Recruitment will start in August 2016 and will be completed in June 2018. Results will be published in peer-reviewed journals, presented at national and international scientific meetings and are expected to inform future national guidelines for exercise
Analysis of a continuous-variable quadripartite cluster state from a single optical parametric oscillator
Midgley, S. L. W.; Olsen, M. K.; Bradley, A. S.; Pfister, O.
We examine the feasibility of generating continuous-variable multipartite entanglement in an intracavity concurrent downconversion scheme that has been proposed for the generation of cluster states by Menicucci et al. [Phys. Rev. Lett. 101, 130501 (2008)]. By calculating optimized versions of the van Loock-Furusawa correlations we demonstrate genuine quadripartite entanglement and investigate the degree of entanglement present. Above the oscillation threshold the basic cluster state geometry under consideration suffers from phase diffusion. We alleviate this problem by incorporating a small injected signal into our analysis. Finally, we investigate squeezed joint operators. While the squeezed joint operators approach zero in the undepleted regime, we find that this is not the case when we consider the full interaction Hamiltonian and the presence of a cavity. In fact, we find that the decay of these operators is minimal in a cavity, and even depletion alone inhibits cluster state formation.
Quantum State Reduction by Matter-Phase-Related Measurements in Optical Lattices
Kozlowski, Wojciech; Caballero-Benitez, Santiago F.; Mekhov, Igor B.
A many-body atomic system coupled to quantized light is subject to weak measurement. Instead of coupling light to the on-site density, we consider the quantum backaction due to the measurement of matter-phase-related variables such as global phase coherence. We show how this unconventional approach opens up new opportunities to affect system evolution. We demonstrate how this can lead to a new class of final states different from those possible with dissipative state preparation or conventional projective measurements. These states are characterised by a combination of Hamiltonian and measurement properties thus extending the measurement postulate for the case of strong competition with the system's own evolution. PMID:28225012
Direct optical access to the triplet manifold of states in H2
NASA Astrophysics Data System (ADS)
Jungen, Ch.; Glass-Maujean, M.
A number of unassigned lines in the absorption spectrum of diatomic hydrogen are attributed to nominally forbidden transitions from the ground state to the n f manifold of states (Rydberg electron with ℓ =3 orbital momentum). They appear via weak ℓ - mixing interactions leading to local level perturbations. Our analysis is based on multichannel quantum defect theory and uses known theoretical information from the literature. The upper levels of most of these transitions are known to give rise to molecular fluorescence, and they are shown to be singlet-triplet mixed. We conclude that the well-known metastable c 3Πu- state can be populated via one-photon absorption of uv photons followed by cascade emission 4 f →3 d →2 p .
Structural and optical properties of solid-state synthesized Au dendritic structures
NASA Astrophysics Data System (ADS)
Gentile, A.; Ruffino, F.; Romano, L.; Boninelli, S.; Reitano, R.; Piccitto, G.; Grimaldi, M. G.
Au dendrites (Au Ds) are synthesized, on various substrates, by a simple physical methodology involving the deposition of a thin Au film on a Si surface followed by thermal processes at high temperatures (>1273 K) in an inert ambient (N2), using fast heating and cooling rates (1273 K/min). Microscopic analyses reveal the evolution, thanks to the thermal processes, of the Au film from a continuous coating to dendritic structures covering the entire sample surface. In particular, transmission electron microscopy analyses indicate that, below the Au surface, the dendritic structures consist of Si atoms originating from the substrate. Furthermore, optical characterizations reveal the ability of the Au Ds to serve as scattering centers in the infrared region. Finally, on the basis of the experimental observations, a phenomenological model for the growth of the Au Ds is proposed.
Topological superfluid state of fermions on a p-band optical square lattice
NASA Astrophysics Data System (ADS)
Wu, Ya-Jie; He, Jing; Zang, Chun-Li; Kou, Su-Peng
In this paper we study an interacting mixture of ultracold spinless fermions on the s band and bosons on the p band in a 2D square optical lattice, of which the effective model is reduced to a p-band fermionic system with nearest-neighbor attractive interaction. From this effective p-band model, we find a translation symmetry protected Z2 topological superfluid that is characterized by a special fermion parity pattern at high-symmetry points in momentum space k=(0,0), (0,π), (π,0), (π,π). Such Z2 topological superfluid supports the robust Majorana edge modes and a new type of low-energy excitation—(supersymmetric) Z2 link excitation.
Efficiency of an enhanced linear optical Bell-state measurement scheme with realistic imperfections
NASA Astrophysics Data System (ADS)
Wein, Stephen; Heshami, Khabat; Fuchs, Christopher A.; Krovi, Hari; Dutton, Zachary; Tittel, Wolfgang; Simon, Christoph
We compare the standard 50%-efficient single beam splitter method for Bell-state measurement to a proposed 75%-efficient auxiliary-photon-enhanced scheme [W. P. Grice, Phys. Rev. A 84, 042331 (2011), 10.1103/PhysRevA.84.042331] in light of realistic conditions. The two schemes are compared with consideration for high input state photon loss, auxiliary state photon loss, detector inefficiency and coupling loss, detector dark counts, and non-number-resolving detectors. We also analyze the two schemes when multiplexed arrays of non-number-resolving detectors are used. Furthermore, we explore the possibility of utilizing spontaneous parametric down-conversion as the auxiliary photon pair source required by the enhanced scheme. In these different cases, we determine the bounds on the detector parameters at which the enhanced scheme becomes superior to the standard scheme and describe the impact of the different imperfections on measurement success rate and discrimination fidelity. This is done using a combination of numeric and analytic techniques. For many of the cases discussed, the size of the Hilbert space and the number of measurement outcomes can be very large, which makes direct numerical solutions computationally costly. To alleviate this problem, all of our numerical computations are performed using pure states. This requires tracking the loss modes until measurement and treating dark counts as variations on measurement outcomes rather than modifications to the state itself. In addition, we provide approximate analytic expressions that illustrate the effect of different imperfections on the Bell-state analyzer quality.
Diffuse optical spectroscopy monitoring of oxygen state and hemoglobin concentration during SKBR-3 tumor model growth
NASA Astrophysics Data System (ADS)
Orlova, A. G.; Kirillin, M. Yu; Volovetsky, A. B.; Shilyagina, N. Yu; Sergeeva, E. A.; Golubiatnikov, G. Yu; Turchin, I. V.
Tumor oxygenation and hemoglobin content are the key indicators of the tumor status which can be efficiently employed for prognosis of tumor development and choice of treatment strategy. We report on monitoring of these parameters in SKBR-3 (human breast adenocarcinoma) tumors established as subcutaneous tumor xenografts in athymic nude mice by diffuse optical spectroscopy (DOS). A simple continuous wave fiber probe DOS system is employed. Optical properties extraction approach is based on diffusion approximation. Statistically significant difference between measured values of normal tissue and tumor are demonstrated. Hemoglobin content in tumor increases from 7.0 ± 4.2 μM to 30.1 ± 16.1 μM with tumor growth from 150 ± 80 mm3 to 1300 ± 650 mm3 which is determined by gradual increase of deoxyhemoglobin content while measured oxyhemoglobin content does not demonstrate any statistically significant variations. Oxygenation in tumor falls quickly from 52.8 ± 24.7% to 20.2 ± 4.8% preceding acceleration of tumor growth. Statistical analysis indicated dependence of oxy-, deoxy- and total hemoglobin on tumor volume (p < 0.01). DOS measurements of oxygen saturation are in agreement with independent measurements of oxygen partial pressure by polarography (Pearson's correlation coefficient equals 0.8).
Background Southeast United States Aerosol Optical Properties and Their Dependence Upon Meteorology
NASA Astrophysics Data System (ADS)
Pawlyszyn, C.; West, M.; Sherman, J. P.; Link, M.; Zhou, Y.
Aerosol effects on SE U.S. radiation budget are highly-seasonal. Aerosol loading is much higher in summer, due largely to high levels of biogenic secondary organic aerosol and sulfates. Aerosol loading is lowest in winter. Aerosol optical properties relevant to radiative forcing have been measured continuously at the Appalachian Atmospheric Interdisciplinary Research facility (AppalAIR) since the summer of 2009. AppalAIR is the only site in the eastern US to house co-located NOAA ESRL and NASA AeroNET instrumentation and is located in the mountains of Boone, NC. Lower tropospheric sub-micron (PM1) light scattering and absorption coefficients measured over seven summers and six winters are presented here, in addition to PM1 organic and sulfate aerosol mass concentrations measured during summers 2012-2013 as well as winter 2013. The objective is to determine the influence of aerosol sources and meteorology along the air mass back-trajectories on aerosol loading and composition. PM1 aerosol mass was dominated by organic aerosol and sulfate during the periods measured. Aerosol light scattering and organic aerosol concentrations were positively correlated during summer with temperature and solar flux along the parcel back-trajectory and negatively-correlated with rainfall along the back-trajectory. Wet deposition was a major factor in the difference between the upper and lower scattering coefficient quartiles for both summer and winter. Summer PM1 light scattering coefficient declined by approximately 30-40% since 2009, with smaller decreases during winter months. Long-term studies of aerosol optical properties from the regionally-representative AppalAIR site are necessary to determine the relationships between changing SE U.S. air quality and aerosol effects on regional climate and weather.
Fault-tolerant linear optical quantum computing with small-amplitude coherent States.
Lund, A P; Ralph, T C; Haselgrove, H L
Quantum computing using two coherent states as a qubit basis is a proposed alternative architecture with lower overheads but has been questioned as a practical way of performing quantum computing due to the fragility of diagonal states with large coherent amplitudes. We show that using error correction only small amplitudes (alpha>1.2) are required for fault-tolerant quantum computing. We study fault tolerance under the effects of small amplitudes and loss using a Monte Carlo simulation. The first encoding level resources are orders of magnitude lower than the best single photon scheme.
Wigner, E.P.; Ohlinger, L.A.; Young, G.J.; Weinberg, A.M.
A reactor which utilizes fissionable fuel elements in rod form immersed in a moderator or heavy water and a means of circulating the heavy water so that it may also function as a coolant to remove the heat generated by the fission of the fuel are described. In this design, the clad fuel elements are held in vertical tubes immersed in heavy water in a tank. The water is circulated in a closed system by entering near the tops of the tubes, passing downward through the tubes over the fuel elements and out into the tank, where it is drawn off at the bottom, passed through heat exchangers to give up its heat and then returned to the tops of the tubes for recirculation.
Moderately luminous Type II supernovae
NASA Astrophysics Data System (ADS)
Inserra, C.; Pastorello, A.; Turatto, M.; Pumo, M. L.; Benetti, S.; Cappellaro, E.; Botticella, M. T.; Bufano, F.; Elias-Rosa, N.; Harutyunyan, A.; Taubenberger, S.; Valenti, S.; Zampieri, L.
Context. Core-collapse Supernovae (CC-SNe) descend from progenitors more massive than about 8 M⊙. Because of the young age of the progenitors, the ejecta may eventually interact with the circumstellar medium (CSM) via highly energetic processes detectable in the radio, X-ray, ultraviolet (UV) and, sometimes, in the optical domains. Aims: In this paper we present ultraviolet, optical and near infrared observations of five Type II SNe, namely SNe 2009dd, 2007pk, 2010aj, 1995ad, and 1996W. Together with few other SNe they form a group of moderately luminous Type II events. We investigate the photometric similarities and differences among these bright objects. We also attempt to characterise them by analysing the spectral evolutions, in order to find some traces of CSM-ejecta interaction. Methods: We collected photometry and spectroscopy with several telescopes in order to construct well-sampled light curves and spectral evolutions from the photospheric to the nebular phases. Both photometry and spectroscopy indicate a degree of heterogeneity in this sample. Modelling the data of SNe 2009dd, 2010aj and 1995ad allows us to constrain the explosion parameters and the properties of the progenitor stars. Results: The light curves have luminous peak magnitudes (-16.95 < MB < -18.70). The ejected masses of 56Ni for three SNe span a wide range of values (2.8 × 10-2 M⊙ < M(56Ni)< 1.4 × 10-1 M⊙), while for a fourth (SN 2010aj) we could determine a stringent upper limit (7 × 10-3 M⊙). Clues of interaction, such as the presence of high velocity (HV) features of the Balmer lines, are visible in the photospheric spectra of SNe 2009dd and 1996W. For SN 2007pk we observe a spectral transition from a Type IIn to a standard Type II SN. Modelling the observations of SNe 2009dd, 2010aj and 1995ad with radiation hydrodynamics codes, we infer kinetic plus thermal energies of about 0.2-0.5 foe, initial radii of 2-5 × 1013 cm and ejected masses of ~5.0-9.5 M⊙. Conclusions: These
Novel solid-state solar thermal simulator supplying 30,000 suns by a fibre optical probe.
Alwahabi, Zeyad T; Kueh, Kimberley C Y; Nathan, Gus J; Cannon, Scott
An efficient 3.168 kW solid-state solar thermal simulator (SSSTS), capable of supplying ~30,000 suns at a focal plane via a fibre optical delivery, has been developed. The source consists of 41 diode lasers, each operated at a wavelength and power of ~915 nm and ~80 watt, respectively. The SSSTS provides a semi-top hat radiation profile and can be focused to a diameter of ~10.5 mm. The electro-optical power efficiency of the SSSTS was evaluated to be 55%, where the maximum value of the uniform radiation flux exceeds 36.6MW/m2. As such, the present technology is relevant to solar thermal applications that are not wavelength-sensitive or where narrow line-width is desirable. Additionally, the fibre optical delivery feature enables ease of direction onto a suitable target, without the need of large ellipsoidal reflectors usually employed for the conventional arc solar simulators. To demonstrate the new SSSTS, ZnO:Zn particles were introduced into the path of the radiation to investigate the change in their own temperature by using the laser induced phosphorescence technique (LIP). The temperature of the averaged particles was measured at a different radiation flux over a ~87 mm2 cross sectional area. A change in the average particle temperature of up to 225°C was detected within the measurement volume when the SSSTS was operated at a flux of ~30,000 suns. The unique characteristics of the SSSTS, namely, the uniformity, high power flux, efficiency, ease of delivery, and precise control of the radiation flux responds to the current demands of solar thermal research.
Changes in the high state of AM Herculis - A simultaneous X-ray, optical, polarimetric, and spectroscopic study
NASA Technical Reports Server (NTRS)
Crosa, L.; Szkody, P.; Stokes, G.; Swank, J.; Wallerstein, G.
Simultaneous UBVR photometry, circular polarimetry, and high resolution spectroscopy observations (during May, 1979), coordinated with a monitor proportional counter and a solid state spectrometer, are reported for the cataclysmic variable AM Her, when it was in its normal 'high' state, where the mean visual magnitude was 12.5 mag versus 15 mag for the infrequent 'low' state. The circular polarization was always negative and had the smallest peak to peak amplitude yet reported. The emission lines He II 4686, H-beta, N III 4634, N III 4640-4641, C III 4650-4651, and He I 4713 present at least two components identified with the broad and sharp components of Greenstein at al. (1977). The radial velocity curve of the broad component shows a 50% reduction of amplitude in comparison to their values, and a third very broad component in 4686 is identified. No correlation between the optical photometry and 1-10 keV X-ray intensity was found on flickering time scales. Results of the observations are discussed within the framework of models with accretion onto one or both magnetic poles of the white dwarf.
Blood flowing state analysis in outflow tract of chick embryonic heart based on spectral domain optical coherence tomography
NASA Astrophysics Data System (ADS)
Zhao, Yuqian; Suo, Yanyan; Liang, Chengbo; Ma, Zhenhe
The cardiac development is a complicated process affected by genetic and environmental factors. Wall shear stress (WSS) and periodic stress (WPS) are the components which have been proved to influence the morphogenesis during early stages of cardiac development. The vessel wall will be deformed by the blood pressure and produce natural elastic force acting on the blood. Because blood flowing in different flow state and show different characteristics of fluid, which influence the calculation of WSS and WPS directly, it is necessary to study the blood flow state. In this paper, we introduce a method to quantify the blood flowing state of early stage chick embryonic heart based on high speed spectral domain optical coherence tomography (SDOCT).4D (x,y,z,t) scan was performed on the outflow tract (OFT) of HH18 (~3 days of incubation) chick embryonic heart. By processing the structural image, the geometric parameters were obtained. Blood flow velocity distribution in the OFT were calculated by Doppler OCT method. Hemodynamic parameters were obtained at different times during the cardiac cycle used biofluid mechanics theory, such as Reynolds number and Womersley number.
The optical Tamm states at the interface between a photonic crystal and a nanocomposite containing core-shell particles
NASA Astrophysics Data System (ADS)
Vetrov, S. Ya; Pankin, P. S.; Timofeev, I. V.
We investigate the optical Tamm states (OTSs) localized at the interface between a photonic crystal (PC) and a nanocomposite consisting of spherical nanoparticles with a dielectric core and a metallic shell, which are dispersed in a transparent matrix, and is characterized by the resonance permittivity. Spectra of transmission, reflection, and absorption of normally incident light waves by the investigated structure are calculated. The spectral manifestation of the Tamm states caused by negative values of the real part of the effective permittivity in the visible spectral range is studied. It is demonstrated that, along with the significantly extended band gap of the PC, the transmission spectrum contains an additional stopband caused by nanocomposite absorption near the resonance frequency. It is shown that the OTSs can be implemented in two band gaps of the PCs, each corresponding to a certain plasmon resonance frequency of the nanocomposite. It is established that the characteristics of the Tamm state localized at the edge of the PCs significantly depend on the ratio between the particle core volume and the total particle volume.
Exciton dynamics in conjugated polymer photovoltaics: Steady-state and time-resolved optical spectroscopy
NASA Astrophysics Data System (ADS)
Chasteen, Stephanie V.
The performance of organic photovoltaics is severely limited by poor exciton dissociation and charge transport due in part to high rates of exciton recombination and low charge mobilities in polymers. This challenge can be partially overcome through the use of blended and layered heterojunctions. Such morphologies offer multiple exciton dissociation sites and separate charge pathways, thus limiting exciton recombination, and allowing for thicker, more absorbing, polymer films. I have performed photovoltaic device characterization and time-resolved and steady-state photoluminescence on a variety of donor-acceptor heterojunction. I have used these methods to understand excited state dynamics and how they affect device performance. As hole-transporters I use a derivative of poly-phenylene-vinylene (M3EH-PPV) and poly-3-hexylthiophene (P3HT). As electron-transporters I use the metal oxide titanium dioxide (TiO2), the electron-transporter CN-PPV, and a fullerene derivative (PCBM). These materials are layered and blended together to form donor-acceptor heterojunctions. All heterojunctions result in enhanced device performance, and 1:4 M3EH-PPV:PCBM resulted in the highest efficiencies. M3EH-PPV emission is characterized by single-chain excitations, and the decay is dominated by short components of 0.20 and 0.45 ns. CN-ether-PPV is dominated by interchain excited state species---ie., excimers---with a decay time of 14.0 ns. The broken conjugation imposed by the ether group affect the excited state, resulting in an excited state species that is particularly vulnerable to quenching. This has important ramifications for material design. Hole-transporting polymers blended and layered with CN-ether-PPV have high currents (Jsc up to 3.3 mA/cm2) and good quenching relative to CN-ether-PPV (˜90%) due to charge separation and generation, respectively. Hole-transporters blended with PCBM result in efficient devices (Jsc up to 14 mA/cm2) due to rapid charge transfer and the
Model-free measurement of the excited-state fraction in a 85Rb magneto-optical trap
NASA Astrophysics Data System (ADS)
Veshapidze, G.; Bang, J.-Y.; Fehrenbach, C. W.; Nguyen, H.; DePaola, B. D.
In many experiments involving magneto-optical traps (MOTs), it is imperative to know the fraction of atoms left in an excited state by the cooling and trapping lasers. In most cases, researchers have used formulas that were derived for simple two-level systems interacting with a single beam of light having a well-defined polarization, and in the absence of magnetic or electric fields. However, a MOT environment is much more complex than this. Here we directly measure the excited fraction in a MOT of 85Rb atoms in a model-independent manner for a wide range of trapping conditions. We then fit our measured fractions to an ansatz based on a simple model. Knowing only the trapping laser's total intensity and detuning from resonance, one can then use this ansatz to accurately predict the excited fraction. The work is a companion piece to similar measurements on a MOT of 87Rb.
Evidence of a hidden-order pseudogap state in URu2Si2 using ultrafast optical spectroscopy
NASA Astrophysics Data System (ADS)
Liu, M. K.; Averitt, R. D.; Durakiewicz, T.; Tobash, P. H.; Bauer, E. D.; Trugman, S. A.; Taylor, A. J.; Yarotski, D. A.
Ultrafast optical spectroscopy was utilized to investigate carrier dynamics in the heavy-fermion compound URu2Si2 from 5 to 300 K. The amplitude and decay time of the photoinduced reflectivity increase in the vicinity of the coherence temperature T*˜57 K, consistent with the presence of a hybridization gap. At 25 K, a crossover regime manifests as a new feature in the carrier dynamics saturating below the hidden-order transition temperature of 17.5 K. This is indicative of a psuedogap region (17.5 K < T < 25 K) separating the normal Kondo-lattice state from the hidden-order phase. Rothwarf-Taylor modeling of the data yields values of ˜10 meV (5 meV) for the hybridization gap (hidden-order gap).
OptaDOS: A tool for obtaining density of states, core-level and optical spectra from electronic structure codes
NASA Astrophysics Data System (ADS)
Morris, Andrew J.; Nicholls, Rebecca J.; Pickard, Chris J.; Yates, Jonathan R.
We present OptaDOS, a program for calculating core-electron and low-loss electron energy loss spectra (EELS) and optical spectra along with total-, projected- and joint-density of electronic states (DOS) from single-particle eigenenergies and dipole transition coefficients. Energy-loss spectroscopy is an important tool for probing bonding within a material. Interpreting these spectra can be aided by first principles calculations. The spectra are generated from the eigenenergies through integration over the Brillouin zone. An important feature of this code is that this integration is performed using a choice of adaptive or linear extrapolation broadening methods which we show produces higher accuracy spectra than standard fixed-width Gaussian broadening. OptaDOS may be straightforwardly interfaced to any electronic structure code. OptaDOS is freely available under the GNU General Public licence from http://www.optados.org.
Quantitative magneto-optical analysis of the role of finite temperatures on the critical state in YBCO thin films
NASA Astrophysics Data System (ADS)
Albrecht, Joachim; Brück, Sebastian; Stahl, Claudia; Ruoß, Stephen
We use quantitative magneto-optical microscopy to investigate the influence of finite temperatures on the critical state of thin YBCO films. In particular, temperature and time dependence of supercurrents in inhomogeneous and anisotropic films are analyzed to extract the role of temperature on the supercurrents themselves and the influence of thermally activated relaxation. We find that inhomogeneities and anisotropies of the current density distribution correspond to a different temperature dependence of local supercurrents. In addition, the thermally activated decay of supercurrents can be used to extract local vortex pinning energies. With these results the modification of vortex pinning introduced by substrate structures is studied. In summary the local investigation of supercurrent densities allows the full description of the vortex pinning landscape with respect to pinning forces and energies in superconducting films with complex properties under the influence of finite temperatures.
Excited state assisted three-photon absorption based optical limiting in nanocrystalline Cu2Se and FeSe2
NASA Astrophysics Data System (ADS)
Anand, Benoy; Molli, Muralikrishna; Aditha, Saikiran; Mimani Rattan, Tanu; Siva Sankara Sai, S.; Kamisetti, Venkataramaniah
Transition metal selenides (FeSe2 and Cu2Se) are synthesized by the hydrothermal co-reduction method. XRD results revealed the crystalline nature of their single phase and the elemental compositions are obtained using EDS. TEM images of the as-prepared samples show the formation of nanorods of 10-20 nm diameter in case of iron selenide and nanoparticles of 10-35 nm diameter in case of copper selenide. The energy bandgap values are calculated using tauc plots obtained from UV-Visible absorption spectra. The open aperture Z-scan measurements carried out using 5 ns pulses at 532 nm revealed that the samples showed excellent optical limiting behavior owing to strong nonlinear absorption (NLA). Through numerical simulations, the mechanism of NLA is found to be effective three-photon absorption which has significant contribution from excited state absorption.
Non-Gaussian states produced by close-to-threshold optical parametric oscillators: Role of classical and quantum fluctuations
NASA Astrophysics Data System (ADS)
D'Auria, V.; de Lisio, C.; Porzio, A.; Solimeno, S.; Anwar, Javaid; Paris, M. G. A.
Quantum states with non-Gaussian statistics generated by optical parametric oscillators (OPO) with fluctuating parameters are studied by means of the kurtosis excess of the external field quadratures. The field generated is viewed as the response of a nonlinear device to the fluctuations of pump laser amplitude and frequency, crystal temperature, and cavity detuning, in addition to quantum noise sources. The kurtosis excess has been evaluated perturbatively up to the third order in the strength of the crystal nonlinear coupling factor and the second order in the classical fluctuating parameters. Applied to the device described in Opt. Expr. 13, 948 (2005), the model has given values of the kurtosis excess in good agreement with the measured ones.
Non-Gaussian states produced by close-to-threshold optical parametric oscillators: Role of classical and quantum fluctuations
D'Auria, V.; Lisio, C. de; Porzio, A.; Solimeno, S.; Anwar, Javaid; Paris, M. G. A.
Quantum states with non-Gaussian statistics generated by optical parametric oscillators (OPO) with fluctuating parameters are studied by means of the kurtosis excess of the external field quadratures. The field generated is viewed as the response of a nonlinear device to the fluctuations of pump laser amplitude and frequency, crystal temperature, and cavity detuning, in addition to quantum noise sources. The kurtosis excess has been evaluated perturbatively up to the third order in the strength of the crystal nonlinear coupling factor and the second order in the classical fluctuating parameters. Applied to the device described in Opt. Expr. 13, 948 (2005), the model has given values of the kurtosis excess in good agreement with the measured ones.
Magnetically stabilized nematic order. II. Critical states and algebraically ordered nematic spin liquids in one-dimensional optical lattices
Zhai Hui; Zhou Fei
We investigate the Zeeman-field-driven quantum phase transitions between singlet spin liquids and algebraically ordered O(2) nematic spin liquids of spin-one bosons in one-dimensional optical lattices. We find that the critical behavior is characterized by condensation of hardcore bosons instead of ideal magnons in high-dimensional lattices. Critical exponents are strongly renormalized by hardcore interactions and critical states are equivalent to the free Fermion model up to the Friedel oscillations. We also find that the algebraically ordered nematic spin liquids close to critical points are fully characterized by the Luttinger-liquid dynamics with Luttinger-liquid parameters magnetically tunable. The Bethe ansatz solution has been applied to determine the critical magnetization and nematic correlations.
Vector and matrix states for Mueller matrices of nondepolarizing optical media.
Kuntman, Ertan; Ali Kuntman, M; Arteaga, Oriol
Nondepolarizing Mueller matrices contain up to seven independent parameters. However, these seven parameters typically do not appear explicitly among the measured 16 parameters of a Mueller matrix, so that they are not directly accessible for physical interpretation. This work shows that all the information contained in a nondepolarizing Mueller matrix can be conveniently expressed in terms of a four component covariance vector state or a generating 4×4 matrix, which can be understood as a matrix state. The generating matrix, besides being directly related to the nondepolarizing Mueller matrix, mimics all properties of the Jones matrix and provides a powerful mathematical tool for formulating all properties of nondepolarizing systems, including the Mueller symmetries and the anisotropy coefficients.
Sympathetic Ground State Cooling and Time-Dilation Shifts in an 27Al+ Optical Clock
NASA Astrophysics Data System (ADS)
Chen, J.-S.; Brewer, S. M.; Chou, C. W.; Wineland, D. J.; Leibrandt, D. R.; Hume, D. B.
We report on Raman sideband cooling of 25Mg+ to sympathetically cool the secular modes of motion in a 25Mg+-27Al+ two-ion pair to near the three-dimensional (3D) ground state. The evolution of the Fock-state distribution during the cooling process is studied using a rate-equation simulation, and various heating sources that limit the efficiency of 3D sideband cooling in our system are discussed. We characterize the residual energy and heating rates of all of the secular modes of motion and estimate a secular motion time-dilation shift of -(1.9 ±0.1 )×10-18 for an 27Al+ clock at a typical clock probe duration of 150 ms. This is a 50-fold reduction in the secular motion time-dilation shift uncertainty in comparison with previous 27Al+ clocks.
Sympathetic Ground State Cooling and Time-Dilation Shifts in an ^{27}Al^{+} Optical Clock.
Chen, J-S; Brewer, S M; Chou, C W; Wineland, D J; Leibrandt, D R; Hume, D B
We report on Raman sideband cooling of ^{25}Mg^{+} to sympathetically cool the secular modes of motion in a ^{25}Mg^{+}-^{27}Al^{+} two-ion pair to near the three-dimensional (3D) ground state. The evolution of the Fock-state distribution during the cooling process is studied using a rate-equation simulation, and various heating sources that limit the efficiency of 3D sideband cooling in our system are discussed. We characterize the residual energy and heating rates of all of the secular modes of motion and estimate a secular motion time-dilation shift of -(1.9±0.1)×10^{-18} for an ^{27}Al^{+} clock at a typical clock probe duration of 150 ms. This is a 50-fold reduction in the secular motion time-dilation shift uncertainty in comparison with previous ^{27}Al^{+} clocks.
A Quantum Electronics Approach to Optical Negative Index Metamaterials (NIMs): Homogeneous NIMs in the Solid State
the specially oriented additional support beam which acts as a perturbation . Consequently, we explore the opportunity, by adjusting the parameters of...relevant dipole moments for the allowed dipole transitions between states with different parities. Afterwards, based on perturbation theory, we have...consider the induced magnetic moment, 21M , due to the inhomogeneous electric field, E r , which causes the dipole moment-type perturbation V̂ : V̂ erE
Radiant, virtual, and dual sources of optical fields in any state of spatial coherence.
Castañeda, Román; Cañas-Cardona, Gustavo; Garcia-Sucerquia, Jorge
A novel description of interference and diffraction with fields in arbitrary states of spatial coherence is introduced in the framework of the phase-space representation. The field is modeled as produced by radiant and virtual point sources. The first ones emit the radiant power of the field, independently of its spatial coherence state, and the second ones emit the modulating energy in strong dependence on such state. This energy can take on positive and negative values that produce the interference and diffraction patterns after adding them to the radiant energy. Radiant and virtual point sources at a given plane can be arranged over two distinct layers, which can be brought together to provide a unified structure of point sources for the field at such plane. So, the coincidence of specific radiant and virtual sources at the same point induces a further type: the dual point source. Descriptions of diffraction arrangements, Young's experiment with diffraction effects, and some implications of this model are discussed.
Solid state synthesis, crystal growth and optical properties of urea and p-chloronitrobenzene solid solution
NASA Astrophysics Data System (ADS)
Rai, R. N.; Kant, Shiva; Reddi, R. S. B.; Ganesamoorthy, S.; Gupta, P. K.
Urea is an attractive material for frequency conversion of high power lasers to UV (for wavelength down to 190 nm), but its usage is hindered due to its hygroscopic nature, though there is no alternative organic NLO crystal which could be transparent up to 190 nm. The hygroscopic character of urea has been modified by making the solid solution (UCNB) of urea (U) and p-chloronitrobenzene (CNB). The formation of the solid solution of CNB in U is explained on the basis of phase diagram, powder XRD, FTIR, elemental analysis and single crystal XRD studies. The solubility of U, CNB and UCNB in ethanol solution is evaluated at different temperatures. Transparent single crystals of UCNB are grown from its saturated solution in ethanol. Optical properties e.g., second harmonic generation (SHG), refractive index and the band gap for UCNB crystal were measured and their values were compared with the parent compounds. Besides modification in hygroscopic nature, UCNB has also shown the higher SHG signal and mechanical hardness in comparison to urea crystal.
Solid state synthesis, crystal growth and optical properties of urea and p-chloronitrobenzene solid solution
Rai, R.N.; Kant, Shiva; Reddi, R.S.B.; Ganesamoorthy, S.; Gupta, P.K.
Urea is an attractive material for frequency conversion of high power lasers to UV (for wavelength down to 190 nm), but its usage is hindered due to its hygroscopic nature, though there is no alternative organic NLO crystal which could be transparent up to 190 nm. The hygroscopic character of urea has been modified by making the solid solution (UCNB) of urea (U) and p-chloronitrobenzene (CNB). The formation of the solid solution of CNB in U is explained on the basis of phase diagram, powder XRD, FTIR, elemental analysis and single crystal XRD studies. The solubility of U, CNB and UCNB in ethanol solution is evaluated at different temperatures. Transparent single crystals of UCNB are grown from its saturated solution in ethanol. Optical properties e.g., second harmonic generation (SHG), refractive index and the band gap for UCNB crystal were measured and their values were compared with the parent compounds. Besides modification in hygroscopic nature, UCNB has also shown the higher SHG signal and mechanical hardness in comparison to urea crystal. - Highlights: • The hygroscopic character of urea was modified by making the solid solution • Solid solution formation is support by elemental, powder- and single crystal XRD • Crystal of solid solution has higher SHG signal and mechanical stability. • Refractive index and band gap of solid solution crystal have determined.
Nonlinear optical responses to circularly polarized lights of the surface state of a topological insulator
NASA Astrophysics Data System (ADS)
Misawa, Tetsuro; Yokoyama, Takehito; Murakami, Shuichi
Recent photoelectron spectroscopy experiments have revealed the presence of the Dirac cone on the surface of the topological insulator and its spin-splitting due to the spin-orbit interaction. In general, on spin-orbit coupled systems, electric fields induce spin polarizations as linear and nonlinear responses. Here we investigate the inverse Faraday effect on the surface of the topological insulator. The inverse Faraday effect is a non-linear optical effect where a circularly polarized light induces a dc spin polarization. We employ the Keldysh Green's function method to calculate the induced spin polarization and discuss its frequency dependence. In particular, in the low frequency limit, our analytical result gives the spin polarization proportional to the frequency and the square of the lifetime. As for the finite frequency regime, we employ numerical methods to discuss the resonance due to interband transitions. We also discuss the photogalvanic effect, where an illumination of a circular polarized light generates the dc charge current. Lastly, we evaluate those quantities with realistic parameters.[4pt] [1] T. Misawa, T. Yokoyama, S. Murakami, Phys. Rev. B84, 165407 (2011).
State-of-the-art in retinal optical coherence tomography image analysis
Yu, Zeyun; D'Souza, Roshan M.
Optical coherence tomography (OCT) is an emerging imaging modality that has been widely used in the field of biomedical imaging. In the recent past, it has found uses as a diagnostic tool in dermatology, cardiology, and ophthalmology. In this paper we focus on its applications in the field of ophthalmology and retinal imaging. OCT is able to non-invasively produce cross-sectional volumetric images of the tissues which can be used for analysis of tissue structure and properties. Due to the underlying physics, OCT images suffer from a granular pattern, called speckle noise, which restricts the process of interpretation. This requires specialized noise reduction techniques to eliminate the noise while preserving image details. Another major step in OCT image analysis involves the use of segmentation techniques for distinguishing between different structures, especially in retinal OCT volumes. The outcome of this step is usually thickness maps of different retinal layers which are very useful in study of normal/diseased subjects. Lastly, movements of the tissue under imaging as well as the progression of disease in the tissue affect the quality and the proper interpretation of the acquired images which require the use of different image registration techniques. This paper reviews various techniques that are currently used to process raw image data into a form that can be clearly interpreted by clinicians. PMID:26435924
Nanofocusing of the free-space optical energy with plasmonic Tamm states
Niu, Linyu; Xiang, Yinxiao; Luo, Weiwei; Cai, Wei; Qi, Jiwei; Zhang, Xinzheng; Xu, Jingjun
To achieve extreme electromagnetic enhancement, we propose a plasmonic Tamm states (PTSs) configuration based on the metal-insulator-metal Bragg reflector, which is realized by periodically modulating the width of the insulator. Both the thick (2D) and thin (3D) structures are discussed. Through optimization performed by the impedance-based transfer matrix method and the finite difference time domain method, we find that both the electric field and magnetic field intensities can be increased by three orders of magnitude. The field-enhancement inside the PTSs configuration is not limited to extremely sharp waveguide terminal, which can greatly reduce processing difficulties. PMID:27995956
Spin Polarization of the ν=1 Quantum Hall State Via Optical Spectroscopy
NASA Astrophysics Data System (ADS)
Goldberg, B. B.
Recent theoretical work has shown that the response of a 2DES with small g-factor in the spin-polarized state (ν=1) to a change of one quantum of magnetic flux is not a single-particle spin-flip excitation, but rather a macroscopic spin object called a Skyrmion or charged spin-texture excitation (CSTE).(S. L. Sondhi, A. Karlhede, S. A. Kivelson, and E. H. Rezayi, Phys. Rev. B 47), 16419 (1993); H. A. Fertig, L. Brey, R. Cote, and A. H. MacDonald, Phys. Rev. B 50, 11018 (1994) Evidence of these excitations have been recently observed in NMR and in tilted-field transport measurements.(S. E. Barrett, G. Dabbagh, L. N. Pfeiffer, K. W. West, and Z. Tycko, Phys. Rev. Lett. 74), 5112 (1995); A. Schmeller, J. P. Eisenstein, L. N. Pfeiffer, K. W. West, LANL Cond-mat preprint 9506133. They consist of a radial spin density distribution that is reversed at the center but gradually heals to the spin background over a distance of many magnetic lengths. With each particle in a nearly spin-aligned neighborhood, the exchange contribution lowers the energy of the CSTE relative to a single flipped spin. We present an experimental observation of Skyrmions in GaAs through the dramatic reduction in the degree of spin-polarization when the Fermi energy moves off the mid-point of the spin-gap of the lowest Landau level, ν=1. The degree of electron spin polarization as a function of ν is measured through interband magneto-absorption spectroscopy which distinguish the occupancy of the two electron spin-states. The spectra show quenching of absorption to the lower energy, spin-up electron band directly correlated to an increase in the higher energy, spin-down absorption at ν=1. This indicates the spin-up state fills with electrons while the spin-down state empties, providing a large spin-polarization Sz which exhibits a pronounced, symmetric decay when ν deviates from 1. The data provide a measurement of the absolute electron spin and are evidence for the presence of Skyrmion
Optical communication with two-photon coherent states. III - Quantum measurements realizable with photoemissive detectors
NASA Technical Reports Server (NTRS)
Yuen, H. P.; Shapiro, J. H.
Homodyne detection is shown to achieve the same signal-to-noise ratio as the quantum field quadrature measurement, thus providing a receiver which realizes linear modulation TCS performance gain. The full equivalence of homodyne detection and single-quadrature field measurement is established. A heterodyne configuration which uses a TCS image-band oscillator in addition to the usual coherent state local oscillator is studied. Results are obtained by means of a representation theorem which shows that photoemissive detection realizes the photon flux density measurement.
Generation of photon-number squeezed states with a fiber-optic symmetric interferometer.
Hosaka, Aruto; Hirosawa, Kenichi; Sawada, Ryota; Kannari, Fumihiko
We numerically and experimentally demonstrate photon-number squeezed state generation with a symmetric fiber interferometer in an 800-nm wavelength and compared with an asymmetric fiber interferometer, although photon-number squeezed pulses have been generated only with asymmetric interferometers. Even though we obtain -1.0dB squeezing with an asymmetric fiber interferometer, since perfect spectral phase and intensity matching between displacement and signal pulses are achieved with a symmetric fiber interferometer, we obtain better squeezing of -3.1dB. We also numerically calculate and clarify this scheme's usefulness at a 1.55-μm wavelength.
Characterization of the ground state dynamics of proteorhodopsin by NMR and optical spectroscopies.
Stehle, Jochen; Scholz, Frank; Löhr, Frank; Reckel, Sina; Roos, Christian; Blum, Michaela; Braun, Markus; Glaubitz, Clemens; Dötsch, Volker; Wachtveitl, Josef; Schwalbe, Harald
We characterized the dynamics of proteorhodopsin (PR), solubilized in diC7PC, a detergent micelle, by liquid-state NMR spectroscopy at T = 323 K. Insights into the dynamics of PR at different time scales could be obtained and dynamic hot spots could be identified at distinct, functionally relevant regions of the protein, including the BC loop, the EF loop, the N-terminal part of helix F and the C-terminal part of helix G. We further characterize the dependence of the photocycle on different detergents (n-Dodecyl β-D-maltoside DDM; 1,2-diheptanoyl-sn-glycero-3-phosphocholine diC7PC) by ultrafast time-resolved UV/VIS spectroscopy. While the photocycle intermediates of PR in diC7PC and DDM exhibit highly similar spectral characteristics, significant changes in the population of these intermediates are observed. In-situ NMR experiments have been applied to characterize structural changes during the photocycle. Light-induced chemical shift changes detected during the photocycle in diC7PC are very small, in line with the changes in the population of intermediates in the photocycle of proteorhodopsin in diC7PC, where the late O-intermediate populated in DDM is missing and the population is shifted towards an equilibrium of intermediates states (M, N, O) without accumulation of a single populated intermediate.
Optical interferometry at the Heisenberg limit with twin Fock states and parity measurements
NASA Astrophysics Data System (ADS)
Campos, R. A.; Gerry, Christopher C.; Benmoussa, A.
Holland and Burnett [Phys. Rev. Lett. 71, 1355 (1993)] have argued that twin Fock states of equal photon number N injected at both input ports of a Mach-Zehnder interferometer lead to phase measurements with accuracies approaching the Heisenberg limit ΔφHL=1/(2N). However, the method of phase detection suggested by those authors, obtaining the difference of the photocurrents at the output ports of the interferometer, is not sensitive to the phase difference between the two interferometer paths; in fact, the photocurrent vanishes. In this paper we show that the use of parity measurements on just one of the output modes not only is sensitive to the phase difference but that the sensitivity approaches the Heisenberg limit for large N.
Potential for efficient frequency conversion at high average power using solid state nonlinear optical materials
Eimerl, D.
High-average-power frequency conversion using solid state nonlinear materials is discussed. Recent laboratory experience and new developments in design concepts show that current technology, a few tens of watts, may be extended by several orders of magnitude. For example, using KD*P, efficient doubling (>70%) of Nd:YAG at average powers approaching 100 KW is possible; and for doubling to the blue or ultraviolet regions, the average power may approach 1 MW. Configurations using segmented apertures permit essentially unlimited scaling of average power. High average power is achieved by configuring the nonlinear material as a set of thin plates with a large ratio of surface area to volume and by cooling the exposed surfaces with a flowing gas. The design and material fabrication of such a harmonic generator are well within current technology.
Repulsively bound exciton-biexciton states in high-spin fermions in optical lattices
Argueelles, A.; Santos, L.
We show that the interplay between spin-changing collisions and quadratic Zeeman coupling provides a mechanism for the formation of repulsively bound composites in high-spin fermions, which we illustrate by considering spin flips in an initially polarized hard-core one-dimensional Mott insulator of spin-3/2 fermions. We show that after the flips the dynamics is characterized by the creation of two types of exciton-biexciton composites. We analyze the conditions for the existence of these bound states and discuss their intriguing properties. In particular we show that the effective mass and stability of the composites depends nontrivially on spin-changing collisions, on the quadratic Zeeman effect, and on the initial exciton localization. Finally, we show that the composites may remain stable against inelastic collisions, opening the possibility of interesting quantum composite phases.
Optical interferometry at the Heisenberg limit with twin Fock states and parity measurements
Campos, R. A.; Gerry, Christopher C.; Benmoussa, A.
Holland and Burnett [Phys. Rev. Lett. 71, 1355 (1993)] have argued that twin Fock states of equal photon number N injected at both input ports of a Mach-Zehnder interferometer lead to phase measurements with accuracies approaching the Heisenberg limit {delta}{phi}{sub HL}=1/(2N). However, the method of phase detection suggested by those authors, obtaining the difference of the photocurrents at the output ports of the interferometer, is not sensitive to the phase difference between the two interferometer paths; in fact, the photocurrent vanishes. In this paper we show that the use of parity measurements on just one of the output modes not only is sensitive to the phase difference but that the sensitivity approaches the Heisenberg limit for large N.
Ground state properties and non-equilibrium dynamics of hard-core bosons confined on optical lattices
NASA Astrophysics Data System (ADS)
Rigol, Marcos; Muramatsu, Alejandro
We study by means of an exact approach, a gas of hard core bosons (HCB) confined on optical lattices. The ground state properties of such systems are analyzed. Local incompressible phases appear in the system, like in the case of interacting soft-core bosons [1] and fermions [2,3]. The changes in momentum distribution function and in the natural orbitals (effective single particle states) introduced by the formation of such phases are analyzed. We also study non-equilibrium properties for those systems, which within our numerical approach can be obtained exactly for systems with 200 particles on lattices with 3000 sites. In particular we analyze the free expansion of the gas when it is released from the trap turning off the confining potential. We show that the expansion is non-trivial (as opposed to the fermionic case) and new features to be observed in the experiments are analyzed. [1] G. G. Batrouni, V. Rousseau, R. T. Scalettar, M. Rigol, A. Muramatsu, P. J. H. Denteneer, and M. Troyer, Phys. Rev. Lett. 89, 117203 (2002). [2] M. Rigol, A. Muramatsu, G. G. Batrouni, and R. T. Scalettar, Phys. Rev. Lett. 91, 130403 (2003). [3] M. Rigol and A. Muramatsu, cond-mat/0309670 (2003).
Amorphization-induced strong localization of electronic states in CsPbBr3 and CsPbCl3 studied by optical absorption measurements
NASA Astrophysics Data System (ADS)
Kondo, S.; Sakai, T.; Tanaka, H.; Saito, T.
Optical absorption spectra of amorphous CsPbX3 films (X=Br,Cl) are characterized by two Gaussian bands near the fundamental edge, with the optical energy gap largely blueshifted and the absorption intensity strongly reduced as compared with the crystalline films. The peak energies of the bands are close to those of the A and C bands of Pb-doped alkali halides. The spectral features are discussed in terms of a molecular orbital theory based on a quasicomplex Pb2+(X-)6 model similar to the complex model for the doped alkali halides. It is shown that not only Pb2+ 6s and 6p extended states near the band edges but also X- p states contributing to upper valence bands are localized by amorphization. The transitions from the localized Pb2+ 6s to 6p states produce the spin-orbit allowed 3P1 and dipole allowed 1P1 states responsible for the two Gaussians. The localized X- p states lie deeper in energy than the localized Pb2+ 6s state and only contribute to higher-energy absorption above the Gaussian bands, giving the reason for the reduced absorption near the fundamental edge. The blueshift of the optical energy gap is attributed to the disappearance of k dispersions for these one-electron states.
Resonant optical properties of AlGaAs/GaAs multiple-quantum-well based Bragg structure at the second quantum state
NASA Astrophysics Data System (ADS)
Chen, Y.; Maharjan, N.; Liu, Z.; Nakarmi, M. L.; Chaldyshev, V. V.; Kundelev, E. V.; Poddubny, A. N.; Vasil'ev, A. P.; Yagovkina, M. A.; Shakya, N. M.
An AlGaAs/GaAs multiple-quantum-well based resonant Bragg structure was designed to match the optical Bragg resonance with the exciton-polariton resonance at the second quantum state in the GaAs quantum wells. The sample structure with 60 periods of AlGaAs/GaAs quantum wells was grown on a semi-insulating GaAs substrate by molecular beam epitaxy. Angle- and temperature-dependent photoluminescence, optical reflectance, and electro-reflectance spectroscopies were employed to study the resonant optical properties of the Bragg structure. Broad and enhanced optical and electro-reflectance features were observed when the Bragg resonance was tuned to the second quantum state of the GaAs quantum well excitons, manifesting a strong light-matter interaction. From the electro-optical experiments, we found the electro-reflectance features related to the transitions of x(e2-hh2) and x(e2-hh1) excitons. The excitonic transition x(e2-hh1), which is prohibited at zero electric field, was allowed by a DC bias due to the brake of symmetry and increased overlap of the electron and hole wave functions caused by the electric field. By tuning the Bragg resonance frequency, we have observed the electro-reflectance feature related to the second quantum state up to room temperature, which evidences a robust light-matter interaction in the resonant Bragg structure.
Effects of surface states, defects and dopants on the optical and magnetic properties of low-dimensional materials
NASA Astrophysics Data System (ADS)
Podila, Ramakrishna
Nanomaterials have attracted the attention of researchers from various fields due to their unique features (that are otherwise absent in the bulk) such as quantum confinement, high surface to volume ratio, ability for surface modification etc. Since the discovery of fullerenes and carbon nanotubes, several synthesis techniques have been developed for nanomaterial growth. However, different control parameters in different synthesis techniques often result in nanostructures with varying defects that may alter their fundamental behavior. Such defects or disorder in the crystal lattice can lead to the disruption of lattice symmetry. The defect-induced symmetry lowering (or breaking) effects play a vital role in the determination of fundamental material characteristics. Thus, it is very important to characterize the defects in order to understand their effects on the nanomaterial properties. This thesis describes the effects of defects in low dimesional systems such as ZnO nanowires, graphene and carbon nanotubes are studied. Firstly, it describes the synthesis and characterization of ZnO nanostructures and discusses the effects of surface states, defects and dopants on their optical and magnetic properties. An unexpected presence of ferromagnetic (FM) ordering in nanostructured nonmagnetic metal oxides has been reported previously. Though this property was attributed to the presence of defects, systematic experimental and theoretical studies to pinpoint its origin and mechanism were lacking. While it is widely believed that oxygen vacancies are responsible for FM ordering, surprisingly annealing as-prepared samples at low temperature (high temperature) in flowing oxygen actually enhances (diminishes) the FM ordering. For these reasons, we have prepared, annealed in different environments, and measured the ensuing magnetization in micrometer and nanoscale ZnO with varying crystallinity. We further find from our magnetization measurements and ab-initio calculations that
All-optical Q-switching limiter for high-power gigahertz modelocked diode-pumped solid-state lasers.
Klenner, Alexander; Keller, Ursula
Passively modelocked diode-pumped solid-state lasers (DPSSLs) with pulse repetition rates in the gigahertz regime suffer from an increased tendency for Q-switching instabilities. Low saturation fluence intracavity saturable absorbers - such as the semiconductor saturable absorber mirrors (SESAMs) - can solve this problem up to a certain average output power limited by the onset of SESAM damage. Here we present a passive stabilization mechanism, an all-optical Q-switching limiter, to reduce the impact of Q-switching instabilities and increase the potential output power of SESAM modelocked lasers in the gigahertz regime. With a proper cavity design a Kerr lens induced negative saturable absorber clamps the maximum fluence on the SESAM and therefore limits the onset of Q-switching instabilities. No critical cavity alignment is required because this Q-switching limiter acts well within the cavity stability regime. Using a proper cavity design, a high-power diode-pumped Yb:CALGO solid-state laser generated sub-100 fs pulses with an average output power of 4.1 W at a pulse repetition rate of 5 GHz. With a pulse duration of 96 fs we can achieve a peak power as high as 7.5 kW directly from the SESAM modelocked laser oscillator without any further external pulse amplification and/or pulse compression. We present a quantitative analysis of this Kerr lens induced Q-switching limiter and its impact on modelocked operation. Our work provides a route to compact high-power multi-gigahertz frequency combs based on SESAM modelocked diode-pumped solid-state lasers without any additional external amplification or pulse compression.
Optical Properties and Mixing State of Aerosols from Residential Wood Burning and Vehicle Emissions in Central and Southern California
NASA Astrophysics Data System (ADS)
Zhang, X.; Cappa, C. D.; Collier, S.; Zhang, Q.; Williams, L. R.; Lee, A.; Abbatt, J.; Russell, L. M.; Liu, J.; Chen, C. L.; Betha, R.
Light-absorbing materials such as black carbon (BC) and brown carbon (BrC) in atmospheric aerosols play important roles in regulating the earth's radiative budget and climate. However, the representations of BC and BrC in state-of-the-art climate models remain highly uncertain, in part due to the poor understanding of their microphysical and optical properties. Direct observations and characterizations of the mixing state and absorption enhancement of ambient aerosols could provide invaluable constraints for current model representations of aerosol radiative effects. Here, we will discuss results from measurements of aerosol light absorption and absorption enhancement (Eabs), using a thermodenuder-absorption method, made during two recent field studies in central and southern California. The winter study took place in Dec/Jan of 2014/2015 in Fresno, CA. This region is severely impacted by particulate matter from local and regional residential biomass burning. The summer study took place in July 2015 in Fontana, CA, a region ~80 km downwind of Los Angeles and strongly impacted by vehicular emissions, and thus provides a sharp contrast to the Fresno study. Eabs of BC particles due to the "lensing" effect from coatings to BC core and/or the presence of BrC will be quantified and compared between the two studies. Additionally, the chemical composition of bulk and the BC-containing particles are determined via a HR-ToF-AMS and a SP-AMS, respectively. Variations in the composition and mixing state of the ambient particles and how these affect the observed Eabs will be examined. The overall measurements suggest a relatively small role for lensing-induced absorption enhancements for ambient particles in these regions.
Optical and magnetic studies on the phosphorescent state of phthalazine in polar and non-polar hosts
NASA Astrophysics Data System (ADS)
Yamauchi, Seigo; Ueno, Tetsuo; Hirota, Noboru
The optical and magnetic properties of the lowest triplet state (T1) of phthalazine were investigated in benzoic acid (BAC), p-dichlorobenzene (DCB) and p-dibromobenzene (DBB) by means of phosphorescence spectroscopy, ODMR and E.P.R. at liquid helium temperatures. Well resolved phosphorescence spectra were observed in DCB and DBB and a vibrational analysis of the spectra was made. The transition energies of the T2(nπ*) and the S1(nπ*) states were estimated from the excitation spectra. The energy gaps between T1 and T2 were estimated to be 2150, 694 and 788 cm-1 in BAC, DCB and DBB, respectively. The sublevel schemes and the zero field splittings (ZFS) were determined. The observed changes of the ZFS on going from the polar to the non-polar hosts are discussed in terms of the vibronic and spin-orbit interactions with the nearby T2(nπ*) state. The most radiative sublevel was found to be T2 in DCB, but Ty in BAC. This difference is attributed to the shifts of the energy levels and the reduction of the molecular symmetry in the polar host. In the non-radiative decay Ty was found to be the most active. Tremendous increases in the non-radiative decay rate constants were observed on going from BAC to DCB. Possible explanations for these observations are presented. The external heavy atom effect on the phosphorescence was observed in the case of DBB. The mechanisms enhancing the radiative decay rates, including those for the vibronic bands are discussed.
Pressure-dependent optical investigations of Fabre salts in the charge-ordered state
NASA Astrophysics Data System (ADS)
Voloshenko, Ievgen; Herter, Melina; Beyer, Rebeca; Pustogow, Andrej; Dressel, Martin
In a comprehensive infrared study, the molecular vibrational features of (TMTTF)2SbF6, (TMTTF)2AsF6 and (TMTTF)2PF6 single crystals have been measured down to temperatures as low as 7 K by applying hydrostatic pressure up to 11 kbar. We follow the charge disproportionation below the critical temperatures T CO as pressure increases, and determine the critical pressure values p CO at which the charge-ordered phase is suppressed. The coexistence of the spin-Peierls phase with charge order is explored at low temperatures, and the competition of these two phases is observed. Based on our measurements we construct a generic phase diagram of the Fabre salts with centrosymmetric anions. The pressure-dependent anion and methyl-group dynamics in these quasi-one-dimensional charge transfer compounds yields information about the interplay of the organic molecules in the stacks and the anions, and how this interaction varies upon the transition to the charge-ordered state.
Field-effect modulation of the local density of optical states in a reflectarray metasurface (Conference Presentation)
NASA Astrophysics Data System (ADS)
Kafaie Shirmanesh, Ghazaleh; Sokhoyan, Ruzan; Han, Seunghoon; Atwater, Harry A.
During recent years, advances in the design of arrays of subwavelength optical elements with special electromagnetic properties have enabled quasi two-dimensional structures that control and manipulate electromagnetic phase, amplitude and polarization. Active control of the response of metasurfaces is possible using transparent conducting oxides such as Indium Tin Oxide (ITO) as a tunable active material [1]. Changing the complex permittivity of ITO by applying a voltage yields modulation of reflected wave phase and amplitude. To achieve this, we designed subwavelength antenna arrays consisting of a gold back reflector and gold fishbone antennas. Planar dielectric layers containing a gate tunable layer of ITO are sandwiched between the back reflector and the antenna. The obtained structure shows resonance around 1.5 µm. As a result, based on the 1.54 µm photoluminescence emission of Er doped Al2O3 films, we embedded trivalent erbium ions as quantum emitters inside an alumina host within the metasurface in order to enhance the local density of optical states (LDOS). Simulations indicate the designed structure shows a significant LDOS enhancement (of order of hundreds). By applying a bias between the antenna and the ITO layer, across an HfO2 gate dielectric, we can control the permittivity of ITO and hence dynamically modulate the decay rate of quantum emitters embedded within the structure. In this way, we can achieve LDOS enhancement modulation of about 325%. 1. Y. W Huang, H. W. H. Lee, R. Sokhoyan, R. Pala, K. Thyagarajan, S. Han, D. P. Tsai, H. A. Atwater, "Gate-tunable conducting oxide metasurfaces". (arXiv:1511.09380).
Spectral, mechanical, thermal, optical and solid state parameters, of metal-organic bis(hydrogenmaleate)-CO(II) tetrahydrate crystal
Chandran, Senthilkumar; Jagan, R.; Paulraj, Rajesh; Ramasamy, P.
Metal-organic bis(hydrogenmaleate)-Co(II) tetrahydrate single crystals have been grown by slow evaporation solution growth technique at room temperature. The crystal structure and the unit cell parameters were analyzed from the X-ray diffraction studies. Single-crystal X-ray diffraction analyses reveal that the grown crystal belongs to triclinic system with the space group P-1. Functional groups in bis(hydrogenmaleate)-Co(II) tetrahydrate were identified by Fourier transform infrared spectral analysis. The peak observed at 663 cm{sup −1} is assigned to the (Co–O) stretching vibrations. The optical transmission of the crystal was studied by UV–vis–NIR spectral analysis. The photoluminescence emission studies were carried out for the title compound in a wide wavelength range between 350 nm and 550 nm at 303 K. Mechanical strength was tested by Vickers microhardness test. The laser damage threshold value has been determined using Nd:YAG laser operating at 1064 nm. At various frequencies and temperatures the dielectric behavior of the material was investigated. Solid state parameters such as plasma energy, Penn gap, Fermi energy and electronic polarizability were evaluated. Photoconductivity measurements were carried out for the grown crystal in the presence of DC electric field at room temperature. Thermal stability and decomposition of the crystal were studied by TG–DTA. The weight loss of the title compound occurs in different steps. - Graphical abstract: Molecular structure of the bis(hydrogenmaleate)-Co(II) tetrahydrate drawn at 40% ellipsoid probability level. - Highlights: • Bis(hydrogenmaleate)-Co(II) tetrahydrate single crystal is grown by slow evaporation method. • Structural and optical properties were discussed. • The title complex crystal is thermally stable up to 91 °C. • Plasma energy, Fermi energy and electronic polarizability are evaluated. • It exhibits positive photoconductivity.
Garcia, Ernest J; Polosky, Marc A
An optical switch reliably maintains its on or off state even when subjected to environments where the switch is bumped or otherwise moved. In addition, the optical switch maintains its on or off state indefinitely without requiring external power. External power is used only to transition the switch from one state to the other. The optical switch is configured with a fixed optical fiber and a movable optical fiber. The movable optical fiber is guided by various actuators in conjunction with a latching mechanism that configure the switch in one position that corresponds to the on state and in another position that corresponds to the off state.
Exact symmetries of electron Bloch states and optical selection rules in [001] GaAs/AlAs quantum wells and superlattices
NASA Astrophysics Data System (ADS)
Tronc, P.; Kitaev, Yu. E.
We determined the exact symmetries of conduction and valence Bloch states in type-I and type-II [001] (GaAs)m(AlAs)n superlattices at the Γ point and at some other symmetry points of the Brillouin zone of the superlattices and derived optical selection rules. Contrary to a result widely accepted in the envelope-function approximation (EFA), pz atomic orbitals cannot mix with px and py orbitals to build Bloch states. The phonon-assisted transitions involving the Γ point as an initial or final state are allowed both without and with taking into account the spin-orbit interaction whatever are the symmetries of the initial and final states. The electron band structure of the superlattices is discussed. Within the domain of validity of EFA (i.e., for not too small values of m and n), a detailed analysis of the Bloch-state symmetry and selection rules is provided on imposing invariance of the superlattice structure under the change of z to -z (the σz symmetry operation). It is shown that optical transitions between the conduction states arising from the Γ states of GaAs on one hand and the conduction states arising from the X states of AlAs on the other hand can be allowed from spin-orbit coupling only. The correspondence is provided between the symmetry of a Bloch state and the parity with respect to σz of its associated envelope function. The effect of an electric field parallel to the growth axis is discussed. Quantum wells do not differ from superlattices with regard to Bloch-state and envelope-function symmetries or optical selection rules. All the above results are still valid for any pseudomorphic superlattice or quantum well made of two binary compounds with zinc-blend structure and identical cations or anions, such as, for example, in the GaN/AlN system.
Mid-IR (4-5 µm) femtosecond multipass amplification of optical parametric seed pulse up to gigawatt level in Fe2+:ZnSe with optical pumping by a solid-state 3 µm laser
NASA Astrophysics Data System (ADS)
Potemkin, F. V.; Migal, E. A.; Pushkin, A. V.; Sirotkin, A. A.; Kozlovsky, V. I.; Korostelin, Yu V.; Podmar'kov, Yu P.; Firsov, V. V.; Frolov, M. P.; Gordienko, V. M.
We demonstrate a first-of-its-kind efficient amplification of a broadband tunable (from 3.8 to 4.8 µm) mid-IR femtosecond seed pulse generated from a AgGaS2-based optical parametric amplifier pumped by a Cr:forsterite laser in a multi-pass Fe2+:ZnSe amplifier optically pumped by a solid-state nanosecond Cr:Yb:Ho:YSGG laser. A total gain of 2000 for an input seed energy of 40 nJ has been obtained. The magnitude of the output energy reaches 80 µJ at a pulse duration of 200 fs.
A combined matrix isolation spectroscopy and cryosolid positron moderation apparatus
Molek, Christopher D.; Michael Lindsay, C.; Fajardo, Mario E.
We describe the design, construction, and operation of a novel apparatus for investigating efficiency improvements in thin-film cryogenic solid positron moderators. We report results from solid neon, argon, krypton, and xenon positron moderators which illustrate the capabilities and limitations of our apparatus. We integrate a matrix isolation spectroscopy diagnostic within a reflection-geometry positron moderation system. We report the optical thickness, impurity content, and impurity trapping site structures within our moderators determined from infrared absorption spectra. We use a retarding potential analyzer to modulate the flow of slow positrons, and report positron currents vs. retarding potential for the different moderators. We identify vacuum ultraviolet emissions from irradiated Ne moderators as the source of spurious signals in our channel electron multiplier slow positron detection channel. Our design is also unusual in that it employs a sealed radioactive Na-22 positron source which can be translated relative to, and isolated from, the cryogenic moderator deposition substrate. This allows us to separate the influences on moderator efficiency of surface contamination by residual gases from those of accumulated radiation damage.
Tunable emission and excited state absorption induced optical limiting in Tb2(MoO4)3: Sm3+/Eu3+ nanophosphors
NASA Astrophysics Data System (ADS)
Mani, Kamal P.; Sreekanth, Perumbilavil; Vimal, G.; Biju, P. R.; Unnikrishnan, N. V.; Ittyachen, M. A.; Philip, Reji; Joseph, Cyriac
Photoluminescence properties and optical limiting behavior of pure and Sm3+/Eu3+ doped Tb2(MoO4)3 nanophosphors are investigated. The prepared nanophosphors exhibit excellent emission when excited by UV light. Color-tunable emissions in Tb2-xSmx(MoO4)3 and Tb2-xEux(MoO4)3 are realized by employing different excitation wavelengths or by controlling the doping concentration of Sm3+ and Eu3+. Luminescence quantum yield and CIE chromatic coordinates of the prepared phosphors were also presented. Optical limiting properties of the samples are investigated by open aperture Z-scan technique using 5 ns laser pulses at 532 nm. Numerical fitting of the measured Z-scan data to the relevant nonlinear transmission equations reveals that the nonlinear absorption is arising from strong excited state absorption, along with weak absorption saturation and it is found that the optical nonlinearity of Tb2(MoO4)3 increases with Sm3+/Eu3+doping. Parameters such as saturation fluence, excited state absorption cross section and ground state absorption cross section of the samples have been determined numerically, from which the figure of merit for nonlinear absorption is calculated. The excited state absorption cross-section of the samples is found to be one order of magnitude higher than that of the ground state absorption cross-section, indicating strong reverse saturable absorption. These results indicate that Sm3+/Eu3+ doped Tb2(MoO4)3 nanophosphors are efficient media for UV/n-UV pumped LEDs, and are also potential candidates for designing efficient optical limiting devices for the protection of human eyes and sensitive optical detectors from harmful laser radiation.
Assessment and statistical modeling of the relationship between remotely sensed aerosol optical depth and PM2.5 in the eastern United States.
Paciorek, Christopher J; Liu, Yang
Research in scientific, public health, and policy disciplines relating to the environment increasingly makes use of high-dimensional remote sensing and the output of numerical models in conjunction with traditional observations. Given the public health and resultant public policy implications of the potential health effects of particulate matter (PM*) air pollution, specifically fine PM with an aerodynamic diameter < or = 2.5 pm (PM2.5), there has been substantial recent interest in the use of remote-sensing information, in particular aerosol optical depth (AOD) retrieved from satellites, to help characterize variability in ground-level PM2.5 concentrations in space and time. While the United States and some other developed countries have extensive PM monitoring networks, gaps in data across space and time necessarily occur; the hope is that remote sensing can help fill these gaps. In this report, we are particularly interested in using remote-sensing data to inform estimates of spatial patterns in ambient PM2.5 concentrations at monthly and longer time scales for use in epidemiologic analyses. However, we also analyzed daily data to better disentangle spatial and temporal relationships. For AOD to be helpful, it needs to add information beyond that available from the monitoring network. For analyses of chronic health effects, it needs to add information about the concentrations of long-term average PM2.5; therefore, filling the spatial gaps is key. Much recent evidence has shown that AOD is correlated with PM2.5 in the eastern United States, but the use of AOD in exposure analysis for epidemiologic work has been rare, in part because discrepancies necessarily exist between satellite-retrieved estimates of AOD, which is an atmospheric-column average, and ground-level PM2.5. In this report, we summarize the results of a number of empirical analyses and of the development of statistical models for the use of proxy information, in particular satellite AOD, in
Logical and pseudo-logical optical fibre networks based on two-state (binary) optical fibre sensors for industrial monitoring and control systems
NASA Astrophysics Data System (ADS)
Szczot, Feliks
The possibilities of development of logical and pseudo-logical optical fibre networks for monitoring and control of equipment and industrial sites are presented. Such networks composed of simple binary attenuation and optical fibre communication lines may also be used as fast and reliable systems developing a final command signal - logical and/or pseudo-logical, depending or the architecture of network and the type of located sensors. They realise the process similar to standard electronic logical sets but use the optical signal directly on the monitored or controlled device. The analysis of serial and parallel networks was carried out in the "dark" mode detection. The examples of networks in power industry were presented where technical and economical merits of logical and pseudo-logical monitoring and controlling networks are clearly visible.
Serotonin sets the day state in the neurons that control coupling between the optic lobe circadian pacemakers in the cricket Gryllus bimaculatus.
Saifullah, A S M; Tomioka, Kenji
The bilaterally paired optic lobe circadian pacemakers of the cricket Gryllus bimaculatus mutually exchange photic and circadian information to keep their activity synchronized. The information is mediated by a neural pathway, consisting of the so-called medulla bilateral neurons, connecting the medulla areas of the two optic lobes. We investigated the effects of serotonin on the neural activity in this coupling pathway. Spontaneous and light-induced electrical activity of the neurons in the coupling pathway showed daily variations, being more intense during the night than the day. Microinjection of serotonin or a serotonin-receptor agonist, quipazine, into the optic lobe caused a dose- and time-dependent inhibition of spontaneous and light-induced responses, mimicking the day state. The amount of suppression was greater and the recovery from the suppression occurred faster during the night. Application of metergoline, a non-selective serotonin-receptor antagonist, increased spontaneous activity and light-evoked responses during both the day and the night, with higher effect during the day. In addition, metergoline effectively attenuated the effects of serotonin. These facts suggest that in the cricket's optic lobe, serotonin is released during the daytime and sets the day state in the neurons regulating coupling between the bilaterally paired optic lobe circadian pacemakers.
Self-Injurious Thoughts and Behaviors among Youth in an Underserved Area of the Southern United States: Exploring the Moderating Roles of Gender, Racial/Ethnic Background, and School-Level
ERIC Educational Resources Information Center
Latzman, Robert D.; Gratz, Kim L.; Young, John; Heiden, Laurie J.; Damon, John D.; Hight, Terry L.
Despite the clinical relevance of self-injurious thoughts and behaviors (SITB) among youth, little is known about the subset of youth most at-risk for SITB. This study examined the moderating roles of gender, racial/ethnic background, and school-level (and their interactions) on rates of SITB within a large (N = 2638, 52.2% female),…
Electro-optical switching at 1550 nm using a two-state GeSe phase-change layer.
Soref, Richard; Hendrickson, Joshua; Liang, Haibo; Majumdar, Arka; Mu, Jianwei; Li, Xun; Huang, Wei-Ping
New designs for electro-optical free-space and waveguided 2 x 2 switches are presented and analyzed at the 1.55 μm telecoms wavelength. The proposed devices employ a ~10 nm film of GeSe that is electrically actuated to transition the layer forth-and-back from the amorphous to the crystal phase, yielding a switch with two self-sustaining states. This phase change material was selected for its very low absorption loss at the operation wavelength, along with its electro-refraction Δn ~0.6. All switches are cascadeable into N x M devices. The free-space prism-shaped structures use III-V prism material to match the GeSe crystal index. The Si/GeSe/Si "active waveguides" are quite suitable for directional-coupler switches as well as Mach-Zehnder devices-all of which have an active length 16x less than that in the free-carrier art.
Mitral annulus segmentation from four-dimensional ultrasound using a valve state predictor and constrained optical flow.
Schneider, Robert J; Perrin, Douglas P; Vasilyev, Nikolay V; Marx, Gerald R; del Nido, Pedro J; Howe, Robert D
Measurement of the shape and motion of the mitral valve annulus has proven useful in a number of applications, including pathology diagnosis and mitral valve modeling. Current methods to delineate the annulus from four-dimensional (4D) ultrasound, however, either require extensive overhead or user-interaction, become inaccurate as they accumulate tracking error, or they do not account for annular shape or motion. This paper presents a new 4D annulus segmentation method to account for these deficiencies. The method builds on a previously published three-dimensional (3D) annulus segmentation algorithm that accurately and robustly segments the mitral annulus in a frame with a closed valve. In the 4D method, a valve state predictor determines when the valve is closed. Subsequently, the 3D annulus segmentation algorithm finds the annulus in those frames. For frames with an open valve, a constrained optical flow algorithm is used to the track the annulus. The only inputs to the algorithm are the selection of one frame with a closed valve and one user-specified point near the valve, neither of which needs to be precise. The accuracy of the tracking method is shown by comparing the tracking results to manual segmentations made by a group of experts, where an average RMS difference of 1.67±0.63mm was found across 30 tracked frames.
Multi-color optical variability of the TeV blazar Mrk 501 in the low-state
NASA Astrophysics Data System (ADS)
Gupta, A. C.; Deng, W. G.; Joshi, U. C.; Bai, J. M.; Lee, M. G.
We report results based on the monitoring of the BL Lac object Mrk 501 in the optical (B, V and R) passbands from March to May 2000. Observations spread over 12 nights were carried out using 1.2 m Mount Abu Telescope, India and 61 cm Telescope at Sobaeksan Astronomy Observatory, South Korea. The aim is to study the intra-day variability (IDV), short term variability and color variability in the low state of the source. We have detected flux variation of 0.05 mag in the R-band in time scale of 15 min in one night. In the B and V passbands, we have less data points and it is difficult to infer any IDVs. Short term flux variations are also observed in the V and R bands during the observing run. No significant variation in color (B-R) has been detected but (V-R) shows variation during the present observing run. Assuming the shortest observed time scale of variability (15 min) to represent the disk instability or pulsation at a distance of five Schwarschild radii from the black hole (BH), mass of the central BH is estimated ∼1.20 × 108M⊙.