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| versions
list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/9904046 | Haret Rosu | H.C. Rosu | Between Schroedinger and Hermite: Supersymmetric pair of q-deformed
non-local operators | 6 pages, LaTex, a phrase more with respect to v1 (Don't work on sign
errors during weekends!) | Int. J. Theor. Phys. 39 (Sept. 2000) 2191-2196 | null | null | quant-ph | null | A simple version of the q-deformed calculus is used to generate a pair of
q-nonlocal, second-order difference operators by means of deformed counterparts
of Darboux intertwining operators for zero factorization energy. These deformed
non-local operators may be considered as supersymmetric partners and their
structure contains contributions originating in both the Hermite operator and
the quantum harmonic oscillator operator. There are also extra $\pm x$
contributions. The undeformed limit, in which all q-nonlocalities wash out,
corresponds to the usual supersymmetric pair of quantum mechanical harmonic
oscillator Hamiltonians. The more general case of negative factorization energy
is briefly discussed as well
| [
{
"version": "v1",
"created": "Mon, 12 Apr 1999 18:38:20 GMT"
},
{
"version": "v2",
"created": "Mon, 26 Apr 1999 17:20:43 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rosu",
"H. C.",
""
]
] |
quant-ph/9904047 | Jaroslav Rehacek | Jaroslav Rehacek, Zdenek Hradil, Michael Zawisky, Saverio Pascazio,
Helmut Rauch, Jan Perina | Testing of quantum phase in matter wave optics | 8 pages, 4 figures | null | 10.1103/PhysRevA.60.473 | null | quant-ph | null | Various phase concepts may be treated as special cases of the maximum
likelihood estimation. For example the discrete Fourier estimation that
actually coincides with the operational phase of Noh, Fouge`res and Mandel is
obtained for continuous Gaussian signals with phase modulated mean.Since
signals in quantum theory are discrete, a prediction different from that given
by the Gaussian hypothesis should be obtained as the best fit assuming a
discrete Poissonian statistics of the signal. Although the Gaussian estimation
gives a satisfactory approximation for fitting the phase distribution of almost
any state the optimal phase estimation offers in certain cases a measurable
better performance. This has been demonstrated in neutron--optical experiment.
| [
{
"version": "v1",
"created": "Mon, 12 Apr 1999 18:55:33 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Rehacek",
"Jaroslav",
""
],
[
"Hradil",
"Zdenek",
""
],
[
"Zawisky",
"Michael",
""
],
[
"Pascazio",
"Saverio",
""
],
[
"Rauch",
"Helmut",
""
],
[
"Perina",
"Jan",
""
]
] |
quant-ph/9904048 | Valerie Nowak | Stephen L. Adler and Lawrence P. Horwitz | State Vector Collapse Probabilities and Separability of Independent
Systems in Hughston's Stochastic Extension of the Schr\"odinger Equation | 13 pages Revtex, no figures | null | null | IASSNS-HEP-99/36 | quant-ph | null | We give a general proof that Hughston's stochastic extension of the
Schr\"odinger equation leads to state vector collapse to energy eigenstates,
with collapse probabilities given by the quantum mechanical probabilities
computed from the initial state. We also show that for a system composed of
independent subsystems, Hughston's equation separates into similar independent
equations for the each of the subsystems, correlated only through the common
Wiener process that drives the state reduction.
| [
{
"version": "v1",
"created": "Mon, 12 Apr 1999 19:28:04 GMT"
},
{
"version": "v2",
"created": "Wed, 28 Apr 1999 14:25:44 GMT"
},
{
"version": "v3",
"created": "Fri, 14 May 1999 18:33:47 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Adler",
"Stephen L.",
""
],
[
"Horwitz",
"Lawrence P.",
""
]
] |
quant-ph/9904049 | Colin P. Williams | Robert Gingrich (1), Colin P. Williams (2), Nicolas Cerf (3) ((1)
Caltech, (2) Jet Propulsion Laboratory, (3) Universite Libre de Bruxelles) | Generalized Quantum Search with Parallelism | 14 pages, 2 figures | Phys.Rev.A61:052313,2000 | 10.1103/PhysRevA.61.052313 | null | quant-ph | null | We generalize Grover's unstructured quantum search algorithm to enable it to
use an arbitrary starting superposition and an arbitrary unitary matrix
simultaneously. We derive an exact formula for the probability of the
generalized Grover's algorithm succeeding after n iterations. We show that the
fully generalized formula reduces to the special cases considered by previous
authors. We then use the generalized formula to determine the optimal strategy
for using the unstructured quantum search algorithm. On average the optimal
strategy is about 12% better than the naive use of Grover's algorithm. The
speedup obtained is not dramatic but it illustrates that a hybrid use of
quantum computing and classical computing techniques can yield a performance
that is better than either alone. We extend the analysis to the case of a
society of k quantum searches acting in parallel. We derive an analytic formula
that connects the degree of parallelism with the optimal strategy for
k-parallel quantum search. We then derive the formula for the expected speed of
k-parallel quantum search.
| [
{
"version": "v1",
"created": "Mon, 12 Apr 1999 22:01:16 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Gingrich",
"Robert",
""
],
[
"Williams",
"Colin P.",
""
],
[
"Cerf",
"Nicolas",
""
]
] |
quant-ph/9904050 | Juergen Schmidhuber | Juergen Schmidhuber | A Computer Scientist's View of Life, the Universe, and Everything | 9 pages, no figures | In C. Freksa, ed., Foundations of Computer Science: Potential -
Theory - Cognition, Lecture Notes in Computer Science, pp. 201-208, Springer,
1997 | null | null | quant-ph cs.CC cs.CY physics.comp-ph physics.pop-ph | null | Is the universe computable? If so, it may be much cheaper in terms of
information requirements to compute all computable universes instead of just
ours. I apply basic concepts of Kolmogorov complexity theory to the set of
possible universes, and chat about perceived and true randomness, life,
generalization, and learning in a given universe.
| [
{
"version": "v1",
"created": "Tue, 13 Apr 1999 13:36:03 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Schmidhuber",
"Juergen",
""
]
] |
quant-ph/9904051 | Michel Feldmann | Michel Feldmann | New loophole for the EPR paradox | Conversion from html to latex only. 16 pages, 1 figure latex | Found.Phys.Lett. 8 (1995) 41-53 | 10.1007/BF02187530 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We exhibit a classical model free from any paradox which exactly simulates
the spin EPR test. We conclude that Bell's inequality violation is a strictly
classical phenomenon, contrary to a general belief.
| [
{
"version": "v1",
"created": "Tue, 13 Apr 1999 15:07:08 GMT"
},
{
"version": "v2",
"created": "Fri, 26 Dec 2008 13:50:31 GMT"
}
] | 2008-12-26T00:00:00 | [
[
"Feldmann",
"Michel",
""
]
] |
quant-ph/9904052 | Dr. G. Plunien | I. Bednyakov, L. Labzowsky, G. Plunien, G. Soff, V. Karasiev | The Standard Model in Strong Fields: Electroweak Radiative Corrections
for Highly Charged Ions | 27 LaTex pages | Phys.Rev.A61:012103,2000 | 10.1103/PhysRevA.61.012103 | null | quant-ph | null | Electroweak radiative corrections to the matrix elements $<ns_{1/2}|{\hat
H}_{PNC}|n'p_{1/2}>$ are calculated for highly charged hydrogenlike ions. These
matrix elements constitute the basis for the description of the most parity
nonconserving (PNC) processes in atomic physics. The operator ${\hat H}_{PNC}$
represents the parity nonconserving relativistic effective atomic Hamiltonian
at the tree level. The deviation of these calculations from the calculations
valid for the momentum transfer $q^{2}=0$ demonstrates the effect of the strong
field, characterized by the momentum transfer $q^{2}=m_{e}^{2}$ ($m_{e}$ is the
electron mass). This allows for a test of the Standard Model in the presence of
strong fields in experiments with highly charged ions.
| [
{
"version": "v1",
"created": "Tue, 13 Apr 1999 18:13:24 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Bednyakov",
"I.",
""
],
[
"Labzowsky",
"L.",
""
],
[
"Plunien",
"G.",
""
],
[
"Soff",
"G.",
""
],
[
"Karasiev",
"V.",
""
]
] |
quant-ph/9904053 | Constantin Brif | Constantin Brif (Caltech) | Reduction of optimum light power with Heisenberg-limited photon-counting
noise in interferometric gravitational-wave detectors | 5 pages, REVTeX. More info on http://www.ligo.caltech.edu/~cbrif | Phys.Lett. A263 (1999) 15-20 | 10.1016/S0375-9601(99)00714-8 | null | quant-ph gr-qc | null | We study how the behavior of quantum noise, presenting the fundamental limit
on the sensitivity of interferometric gravitational-wave detectors, depends on
properties of input states of light. We analyze the situation with specially
prepared nonclassical input states which reduce the photon-counting noise to
the Heisenberg limit. This results in a great reduction of the optimum light
power needed to achieve the standard quantum limit, compared to the usual
configuration.
| [
{
"version": "v1",
"created": "Tue, 13 Apr 1999 18:48:11 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Brif",
"Constantin",
"",
"Caltech"
]
] |
quant-ph/9904054 | Constantin Brif | C. Brif and A. Mann | Inverted spectroscopy and interferometry for quantum-state
reconstruction of systems with SU(2) symmetry | 8 pages, REVTeX. More info on
http://www.ligo.caltech.edu/~cbrif/science.html | J.Opt.B Quant.Semiclass.Opt. 2 (2000) 245-251 | 10.1088/1464-4266/2/3/305 | null | quant-ph | null | We consider how the conventional spectroscopic and interferometric schemes
can be rearranged to serve for reconstructing quantum states of physical
systems possessing SU(2) symmetry. The discussed systems include a collection
of two-level atoms, a two-mode quantized radiation field with a fixed total
number of photons, and a single laser-cooled ion in a two-dimensional harmonic
trap with a fixed total number of vibrational quanta. In the proposed
rearrangement, the standard spectroscopic and interferometric experiments are
inverted. Usually one measures an unknown frequency or phase shift using a
system prepared in a known quantum state. Our aim is just the inverse one,
i.e., to use a well-calibrated apparatus with known transformation parameters
to measure unknown quantum states.
| [
{
"version": "v1",
"created": "Tue, 13 Apr 1999 18:59:37 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Brif",
"C.",
""
],
[
"Mann",
"A.",
""
]
] |
quant-ph/9904055 | null | A. D Baute, R. Sala Mayato, J. P. Palao, J. G. Muga, and I. L.
Egusquiza | Time-of-arrival distribution for arbitrary potentials and Wigner's
time-energy uncertainty relation | 4 pages, revtex, 2 eps figures included | Phys.Rev.A61:022118,2000 | 10.1103/PhysRevA.61.022118 | ULLFIS 980401 | quant-ph | null | A realization of the concept of "crossing state" invoked, but not
implemented, by Wigner, allows to advance in two important aspects of the time
of arrival in quantum mechanics: (i) For free motion, we find that the
limitations described by Aharonov et al. in Phys. Rev. A 57, 4130 (1998) for
the time-of-arrival uncertainty at low energies for certain mesurement models
are in fact already present in the intrinsic time-of-arrival distribution of
Kijowski; (ii) We have also found a covariant generalization of this
distribution for arbitrary potentials and positions.
| [
{
"version": "v1",
"created": "Tue, 13 Apr 1999 21:32:28 GMT"
},
{
"version": "v2",
"created": "Wed, 14 Apr 1999 20:35:51 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Baute",
"A. D",
""
],
[
"Mayato",
"R. Sala",
""
],
[
"Palao",
"J. P.",
""
],
[
"Muga",
"J. G.",
""
],
[
"Egusquiza",
"I. L.",
""
]
] |
quant-ph/9904056 | Antonio Acin | A. Acin, J.I. Latorre, P. Pascual | Optimal generalized quantum measurements for arbitrary spin systems | LateX, 12 pages | Phys.Rev. A61 (2000) 22113 | 10.1103/PhysRevA.61.022113 | null | quant-ph | null | Positive operator valued measurements on a finite number of N identically
prepared systems of arbitrary spin J are discussed. Pure states are
characterized in terms of Bloch-like vectors restricted by a SU(2 J+1)
covariant constraint. This representation allows for a simple description of
the equations to be fulfilled by optimal measurements. We explicitly find the
minimal POVM for the N=2 case, a rigorous bound for N=3 and set up the analysis
for arbitrary N.
| [
{
"version": "v1",
"created": "Wed, 14 Apr 1999 08:37:50 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Acin",
"A.",
""
],
[
"Latorre",
"J. I.",
""
],
[
"Pascual",
"P.",
""
]
] |
quant-ph/9904057 | Jose Luis Gruver | Jose Luis Gruver | q-deformed dynamics of q-deformed oscillators | 6 pages, RevTex | Phys.Lett. A254 (1999) 1 | 10.1016/S0375-9601(99)00127-9 | null | quant-ph | null | We show that an infinite set of q-deformed relevant operators close a partial
q-deformed Lie algebra under commutation with the Arik-Coon oscillator. The
dynamics is described by the multicommutator: [H,..., [H, O]...], that follows
a power law which leads to a dynamical scaling. We study the dynamics of the
Arik-Coon and anharmonic oscillators and analyze the role of q and the other
parameters in the evolution of both systems.
| [
{
"version": "v1",
"created": "Wed, 14 Apr 1999 12:13:05 GMT"
},
{
"version": "v2",
"created": "Mon, 19 Apr 1999 10:40:04 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Gruver",
"Jose Luis",
""
]
] |
quant-ph/9904058 | Attila Czirjak | M. G. Benedict and A. Czirjak | Wigner functions, squeezing properties and slow decoherence of atomic
Schrodinger cats | RevTeX, 14 pages including 8 PostScript figures. High quality
versions of Figures 1, 3, 5, 7 and 8 are available at
http://www.jate.u-szeged.hu/~benedict/asc_figures.html . (Submitted to
Physical Review A: March 26, 1999.) | Phys.Rev. A60 (1999) 4034 | 10.1103/PhysRevA.60.4034 | null | quant-ph | null | We consider a class of states in an ensemble of two-level atoms: a
superposition of two distinct atomic coherent states, which can be regarded as
atomic analogues of the states usually called Schrodinger cat states in quantum
optics. According to the relation of the constituents we define polar and
nonpolar cat states. The properties of these are investigated by the aid of the
spherical Wigner function. We show that nonpolar cat states generally exhibit
squeezing, the measure of which depends on the separation of the components of
the cat, and also on the number of the constituent atoms. By solving the master
equation for the polar cat state embedded in an external environment, we
determine the characteristic times of decoherence, dissipation and also the
characteristic time of a new parameter, the non-classicality of the state. This
latter one is introduced by the help of the Wigner function, which is used also
to visualize the process. The dependence of the characteristic times on the
number of atoms of the cat and on the temperature of the environment shows that
the decoherence of polar cat states is surprisingly slow.
| [
{
"version": "v1",
"created": "Wed, 14 Apr 1999 12:38:09 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Benedict",
"M. G.",
""
],
[
"Czirjak",
"A.",
""
]
] |
quant-ph/9904059 | Patrick Bardroff | P. J. Bardroff and S. Stenholm | Quantum theory of excess noise | 4 pages, 0 figures, revtex, this version has minor changes and one
additional reference, scheduled for publication SEP99 in PRA | Phys.Rev.A60:2529,1999 | 10.1103/PhysRevA.60.2529 | null | quant-ph | null | We analyze the excess noise in the framework of the conventional quantum
theory of laser-like systems. Our calculation is conceptually simple and our
result also shows a correction to the semi-classical result derived earlier.
| [
{
"version": "v1",
"created": "Wed, 14 Apr 1999 15:50:21 GMT"
},
{
"version": "v2",
"created": "Tue, 22 Jun 1999 15:31:28 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Bardroff",
"P. J.",
""
],
[
"Stenholm",
"S.",
""
]
] |
quant-ph/9904060 | Patrick Bardroff | P. J. Bardroff and S. Stenholm | Quantum Langevin theory of excess noise | 9 pages, 0 figures, revtex | null | 10.1103/PhysRevA.61.023806 | null | quant-ph | null | In an earlier work [P. J. Bardroff and S. Stenholm], we have derived a fully
quantum mechanical description of excess noise in strongly damped lasers. This
theory is used here to derive the corresponding quantum Langevin equations.
Taking the semi-classical limit of these we are able to regain the starting
point of Siegman's treatment of excess noise [Phys. Rev. A 39, 1253 (1989)].
Our results essentially constitute a quantum derivation of his theory and allow
some generalizations.
| [
{
"version": "v1",
"created": "Wed, 14 Apr 1999 16:07:56 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Bardroff",
"P. J.",
""
],
[
"Stenholm",
"S.",
""
]
] |
quant-ph/9904061 | Leonid V. Il'ichov | L.V.Il'ichov | The Dynamic Effect of Quantum Decoherence | 6 pages, LaTeX, no figures | null | null | null | quant-ph | null | An effective force induced by spatially depending decoherence is predicted.
The phenomenon is illustrated by a simple model of a 1/2-spin particle
subjected to distributed unselective measurement of noncommuting spin
components.
| [
{
"version": "v1",
"created": "Thu, 15 Apr 1999 05:42:46 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Il'ichov",
"L. V.",
""
]
] |
quant-ph/9904062 | Andrew Scott Parkins | A.S. Parkins and H.J. Kimble | Quantum state transfer between motion and light | 10 pages, RevTex, 6 figures, to appear in Journal of Optics B:
Quantum and Semiclassical Optics | null | 10.1088/1464-4266/1/4/323 | null | quant-ph | null | We describe schemes for transferring quantum states between light fields and
the motion of a trapped atom. Coupling between the motion and the light is
achieved via Raman transitions driven by a laser field and the quantized field
of a high-finesse microscopic cavity mode. By cascading two such systems and
tailoring laser field pulses, we show that it is possible to transfer an
arbitrary motional state of one atom to a second atom at a spatially distant
site.
| [
{
"version": "v1",
"created": "Thu, 15 Apr 1999 05:44:57 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Parkins",
"A. S.",
""
],
[
"Kimble",
"H. J.",
""
]
] |
quant-ph/9904063 | Konrad Banaszek | Konrad Banaszek | Maximum-likelihood algorithm for quantum tomography | 7 pages LaTeX, contribution to proceedings of 6th central-european
workshop on quantum optics | Acta Phys.Slov. 49 (1999) 633-638 | null | null | quant-ph | null | Optical homodyne tomography is discussed in the context of classical image
processing. Analogies between these two fields are traced and used to formulate
an iterative numerical algorithm for reconstructing the Wigner function from
homodyne statistics.
| [
{
"version": "v1",
"created": "Thu, 15 Apr 1999 13:19:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Banaszek",
"Konrad",
""
]
] |
quant-ph/9904064 | O. B. Zaslavskii | V. V. Ulyanov and O.B.Zaslavskii (Department of Physics, Kharkov State
University) | Tunnelling series in terms of perturbation theory for quantum spin
systems | 7 pages, REVTeX 3.0 | Phys.Rev.B60:6212,1999 | 10.1103/PhysRevB.60.6212 | null | quant-ph cond-mat.stat-mech hep-th | null | Considered is quantum tunnelling in anisotropic spin systems in a magnetic
field perpendicular to the anisotropy axis. In the domain of small field the
problem of calculating tunnelling splitting of energy levels is reduced to
constructing the perturbatio n series with degeneracy, the order of degeneracy
being proportional to a spin value. Partial summation of this series taking
into account ''dangerous terms'' with small denominators is performed and the
value of tunnelling splitting is calculated with allowance for the first
correction with respect to a magnetic field.
| [
{
"version": "v1",
"created": "Thu, 15 Apr 1999 17:23:21 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Ulyanov",
"V. V.",
"",
"Department of Physics, Kharkov State\n University"
],
[
"Zaslavskii",
"O. B.",
"",
"Department of Physics, Kharkov State\n University"
]
] |
quant-ph/9904065 | Alberto Barchielli | Alberto Barchielli and Giancarlo Lupieri | Quantum stochastic models of two-level atoms and electromagnetic cross
sections | 18 pages, 3 Postscript figures, LaTeX | J.Math.Phys. 41 (2000) 7181-7205 | 10.1063/1.1289380 | 356/P | quant-ph | null | Quantum stochastic differential equations have been used to describe the
dynamics of an atom interacting with the electromagnetic field via
absorption/emission processes. Here, by using the full quantum stochastic
Schroedinger equation proposed by Hudson and Parthasarathy fifteen years ago,
we show that such models can be generalized to include other processes into the
interaction. In the case of a two-level atom we construct a model in which the
interaction with the field is due either to absorption/emission processes
either to direct scattering processes, which simulate the interaction due to
virtual transitions to the levels which have been eliminated from the
description. To see the effects of the new terms, the total, elastic and
inelastic eloctromagnetic cross sections are studied. The new power spectrum is
compared with Mollow's results.
| [
{
"version": "v1",
"created": "Fri, 16 Apr 1999 16:37:26 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Barchielli",
"Alberto",
""
],
[
"Lupieri",
"Giancarlo",
""
]
] |
quant-ph/9904066 | Andris Ambainis | Andris Ambainis, Richard Bonner, Rusins Freivalds, Arnolds Kikusts | Probabilities to accept languages by quantum finite automata | 14 pages, to appear in COCOON'99 | null | null | null | quant-ph cs.CC | null | We construct a hierarchy of regular languages such that the current language
in the hierarchy can be accepted by 1-way quantum finite automata with a
probability smaller than the corresponding probability for the preceding
language in the hierarchy. These probabilities converge to 1/2.
| [
{
"version": "v1",
"created": "Fri, 16 Apr 1999 17:35:20 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ambainis",
"Andris",
""
],
[
"Bonner",
"Richard",
""
],
[
"Freivalds",
"Rusins",
""
],
[
"Kikusts",
"Arnolds",
""
]
] |
quant-ph/9904067 | Daniel Jonathan | D. Jonathan, A. Vidiella-Barranco and K. Furuya | Dressed-State Approach to Population Trapping in the Jaynes-Cummings
Model | 24 pages, 5 figures, to appear in J. Mod. Opt | J.Mod.Opt. 46 (1999) 1697 | 10.1080/09500349908231366 | null | quant-ph | null | The phenomenon of atomic population trapping in the Jaynes-Cummings Model is
analysed from a dressed-state point of view. A general condition for the
occurrence of partial or total trapping from an arbitrary, pure initial
atom-field state is obtained in the form of a bound to the variation of the
atomic inversion. More generally, it is found that in the presence of initial
atomic or atom-field coherence the population dynamics is governed not by the
field's initial photon distribution, but by a `weighted dressedness'
distribution characterising the joint atom-field state. In particular,
individual revivals in the inversion can be analytically described to good
approximation in terms of that distribution, even in the limit of large
population trapping. This result is obtained through a generalisation of the
Poisson Summation Formula method for analytical description of revivals
developed by Fleischhauer and Schleich [Phys. Rev. A {\bf 47}, 4258 (1993)].
| [
{
"version": "v1",
"created": "Fri, 16 Apr 1999 18:44:31 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Jonathan",
"D.",
""
],
[
"Vidiella-Barranco",
"A.",
""
],
[
"Furuya",
"K.",
""
]
] |
quant-ph/9904068 | Dr. Arun Kumar Pati | Arun Kumar Pati | "Assisted cloning'' and "orthogonal-complementing" of an unknown state | 7 pages, Latex, no figures, submitted to Phys. Rev. A. 1999(to be
accepted) | Phys.Rev.A61:022308,2000 | 10.1103/PhysRevA.61.022308 | null | quant-ph | null | We propose a protocol where one can exploit dual quantum and classical
channels to achieve perfect ``cloning'' and ``orthogonal-complementing'' of an
unknown state with a minimal assistance from a state preparer (without
revealing what the input state is). The first stage of the protocol requires
usual teleportation and in the second stage, the preparer disentangles the
left-over entangled states by a single particle measurement process and
communicates a number of classical bits (1-cbit per copy) to different parties
so that perfect copies and complement copies are produced. We discuss our
protocol for producing two copies and three copies (and complement copies)
using two and four particle entangled state and suggest how to generalise this
for N copies and complement copies using multiparticle entangled state.
| [
{
"version": "v1",
"created": "Sat, 17 Apr 1999 15:45:37 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Pati",
"Arun Kumar",
""
]
] |
quant-ph/9904069 | Jonas Soderholm | Gunnar Bjork, Jonas Soderholm, Alexei Trifonov, Tedros Tsegaye, Anders
Karlsson | Complementarity and the uncertainty relations | 9 pages, 4 figures, REVTeX, uses epsf.sty and multicol.sty | Phys.Rev. A60 (1999) 1874-1882 | 10.1103/PhysRevA.60.1874 | null | quant-ph | null | We formulate a general complementarity relation starting from any Hermitian
operator with discrete non-degenerate eigenvalues. We then elucidate the
relationship between quantum complementarity and the Heisenberg-Robertson's
uncertainty relation. We show that they are intimately connected. Finally we
exemplify the general theory with some specific suggested experiments.
| [
{
"version": "v1",
"created": "Mon, 19 Apr 1999 08:57:52 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Bjork",
"Gunnar",
""
],
[
"Soderholm",
"Jonas",
""
],
[
"Trifonov",
"Alexei",
""
],
[
"Tsegaye",
"Tedros",
""
],
[
"Karlsson",
"Anders",
""
]
] |
quant-ph/9904070 | Chiara Macchiavello | A. Ekert and C. Macchiavello | Against Quantum Noise | 12 pages. Presented at the International Conference "Quantum Optics
IV", Jaszowiec, Poland, June 17-24 1997. An introductory overview of quantum
dissipation and error correction. Late submission to the archive due to
requests and the limited availability of the journal | Acta Phys.Polon. A93 (1998) 63 | null | null | quant-ph | null | This is a brief description of how to protect quantum states from dissipation
and decoherence that arise due to uncontrolled interactions with the
environment. We discuss recoherence and stabilisation of quantum states based
on two techniques known as "symmetrisation" and "quantum error correction". We
illustrate our considerations with the most popular quantum-optical model of
the system-environment interaction, commonly used to describe spontaneous
emission, and show the benefits of quantum error correction in this case.
| [
{
"version": "v1",
"created": "Mon, 19 Apr 1999 09:05:31 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ekert",
"A.",
""
],
[
"Macchiavello",
"C.",
""
]
] |
quant-ph/9904071 | Konrad Banaszek | Konrad Banaszek and Krzysztof Wodkiewicz | Nonlocality of the Einstein-Podolsky-Rosen state in the phase space | 10 pages LaTeX, contribution to proceedings of 6th central-european
workshop on quantum optics | Acta Phys.Slov. 49 (1999) 491-500 | null | null | quant-ph | null | We discuss violation of Bell inequalities by the regularized
Einstein-Podolsky-Rosen (EPR) state, which can be produced in a quantum optical
parametric down-conversion process. We propose an experimental photodetection
scheme to probe nonlocal quantum correlations exhibited by this state.
Furthermore, we show that the correlation functions measured in two versions of
the experiment are given directly by the Wigner function and the Q function of
the EPR state. Thus, the measurement of these two quasidistribution functions
yields a novel scheme for testing quantum nonlocality.
| [
{
"version": "v1",
"created": "Mon, 19 Apr 1999 09:37:39 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Banaszek",
"Konrad",
""
],
[
"Wodkiewicz",
"Krzysztof",
""
]
] |
quant-ph/9904072 | Bert Schroer | Bert Schroer (FU-Berlin, presently CBPF-Rio de Janeiro) | Basic Quantum Theory and Measurement from the Viewpoint of Local Quantum
Physics | 11 pages tcilatex. This is a condensed version of material prepared
for, and submitted to proceedings of the symposium entitled ``New Insights in
Quantum Mechanics-Fundamentals, Experimental Results and Theoretical
Directions'' Goslar, Germany, September 1-3, 1998 | in Trends in Quantum Mechanics, page 274, edited by H.-.D Doebner,
S.T. Ali, M. Keyl and R.F. | null | null | quant-ph hep-th | null | Several aspects of the manifestation of the causality principle in LQP (local
quantum physics) are reviewed or presented. Particular emphasis is given to
those properties which are typical for LQP in the sense that they do go beyond
the structure of general quantum theory and even escape the Lagrangian
quantization methods of standard QFT. The most remarkable are those relating
causality to the modular Tomita-Takesaki theory, since they bring in the basic
concepts of antiparticles, charge superselections as well as internal and
external (geometric and hidden) symmetries.
| [
{
"version": "v1",
"created": "Mon, 19 Apr 1999 13:39:58 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Schroer",
"Bert",
"",
"FU-Berlin, presently CBPF-Rio de Janeiro"
]
] |
quant-ph/9904073 | Jean-Michel Courty | Francesca Grassia, Jean-Michel Courty, Serge Reynaud (Laboratoire
Kastler Brossel), Pierre Touboul(Departement de Mesures Physiques, ONERA) | Quantum theory of fluctuations in a cold damped accelerometer | 10 pages, 6 figures, RevTeX; Minor changes | Eur.Phys.J. D8 (2000) 101-110 | 10.1007/s10053-000-9071-y | null | quant-ph | null | We present a quantum network approach to real high sensitivity measurements.
Thermal and quantum fluctuations due to active as well as passive elements are
taken into account. The method is applied to the analysis of the capacitive
accelerometer using the cold damping technique, developed for fundamental
physics in space by ONERA and the ultimate limits of this instrument are
discussed. It is confirmed in this quantum analysis that the cold damping
technique allows one to control efficiently the test mass motion without
degrading the noise level.
| [
{
"version": "v1",
"created": "Mon, 19 Apr 1999 13:48:20 GMT"
},
{
"version": "v2",
"created": "Thu, 9 Sep 1999 12:10:06 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Grassia",
"Francesca",
"",
"Laboratoire\n Kastler Brossel"
],
[
"Courty",
"Jean-Michel",
"",
"Laboratoire\n Kastler Brossel"
],
[
"Reynaud",
"Serge",
"",
"Laboratoire\n Kastler Brossel"
],
[
"Touboul",
"Pierre",
"",
"Departement de Mesures Physiques, ONERA"
]
] |
quant-ph/9904074 | Matteo G. A. Paris | G. M. D'Ariano, L. Maccone, M. G. A. Paris, and M. F. Sacchi | Generation and Measurement of Nonclassical States by Quantum Fock Filter | 7 pages LaTeX, contribution to proceedings of 6th central-european
workshop on quantum optics (actaps.sty included) | Acta Phys.Slov. 49 (1999) 659 | null | null | quant-ph | null | We study a novel optical setup which is able to select a specific Fock
component from a generic input state. The device allows to synthesize number
states and superpositions of few number states, and to measure the photon
distribution and the density matrix of a generic input signal.
| [
{
"version": "v1",
"created": "Mon, 19 Apr 1999 15:23:22 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"D'Ariano",
"G. M.",
""
],
[
"Maccone",
"L.",
""
],
[
"Paris",
"M. G. A.",
""
],
[
"Sacchi",
"M. F.",
""
]
] |
quant-ph/9904075 | R. Srikanth | R. Srikanth | Noncausal Superluminal Nonlocal Signalling | Includes a refinement of the thought-experiment presented earlier, 4
figures (new); Two sections added: to explain how no-signalling arguments are
circumvented; and to propose a plan for a possible practical realization of
the thought-experiment | null | null | IIAp-99/7/1 | quant-ph | null | We propose a thought experiment for classical superluminal signal
transmission based on the quantum nonlocal influence of photons on their
momentum entangled EPR twins. The signal sender measures either position or
momentum of particles in a pure ensemble of the entangled pairs, leaving their
twins as localized particles or plane waves. The signal receiver distinguishes
these outcomes interferometrically using a double slit interferometer modified
by a system of optical filters. Since the collapse of the wavefunction is
postulated to be instantaneous, this signal can be transmitted superluminally.
We show that the method circumvents the no-signalling theorem because the
receiver is able to modify the disentangled wavefunction before his
measurement. We propose a plan for the possible practical realization of a
superluminal quantum telegraph based on the thought experiment.
| [
{
"version": "v1",
"created": "Tue, 20 Apr 1999 22:45:03 GMT"
},
{
"version": "v2",
"created": "Wed, 28 Apr 1999 00:46:27 GMT"
},
{
"version": "v3",
"created": "Tue, 6 Jul 1999 17:11:41 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Srikanth",
"R.",
""
]
] |
quant-ph/9904076 | Paolo Facchi | S. Pascazio and P. Facchi | Modifying the lifetime of an unstable system by an intense
electromagnetic field | 10 pages, 3 figures. Contribution to Sixth Central-European Workshop
on Quantum Optics, Chudobin near Olomouc, Czech Republic, April-May 1999 | Acta Phys.Slov. 49 (1999) 557-566 | null | null | quant-ph | null | We study the temporal behavior of a three-level system (such as an atom or a
molecule), initially prepared in an excited state, bathed in a laser field
tuned at the transition frequency of the other level. We analyze the dependence
of the lifetime of the initial state on the intensity of the laser field. The
phenomenon we discuss is related to both electromagnetic induced transparency
and quantum Zeno effect.
| [
{
"version": "v1",
"created": "Wed, 21 Apr 1999 08:46:12 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Pascazio",
"S.",
""
],
[
"Facchi",
"P.",
""
]
] |
quant-ph/9904077 | Gui Lu Long | Gui Lu Long, Wei Lin Zhang, Yan Song Li and Li Niu | Arbitrary phase rotation of the marked state can not be used for
Grover's quantum search algorithm | 5 pages, 5 figures | Commun.Theor.Phys. 32 (1999) 335-338 | 10.1088/0253-6102/32/3/335 | null | quant-ph | null | A misunderstanding that an arbitrary phase rotation of the marked state
together with the inversion about average operation in Grover's search
algorithm can be used to construct a (less efficient) quantum search algorithm
is cleared. The $\pi$ rotation of the phase of the marked state is not only the
choice for efficiency, but also vital in Grover's quantum search algorithm. The
results also show that Grover's quantum search algorithm is robust.
| [
{
"version": "v1",
"created": "Wed, 21 Apr 1999 22:09:50 GMT"
}
] | 2018-01-17T00:00:00 | [
[
"Long",
"Gui Lu",
""
],
[
"Zhang",
"Wei Lin",
""
],
[
"Li",
"Yan Song",
""
],
[
"Niu",
"Li",
""
]
] |
quant-ph/9904078 | Dominic Mayers | Dominic Mayers, Louis Salvail and Yoshie Chiba-Kohno | Unconditionally Secure Quantum Coin Tossing | 7 pages Revtex format It is known to be impossible. There was no
claimed proof in the paper. It is just a bad intuition | null | null | null | quant-ph | null | In coin tossing two remote participants want to share a uniformly distributed
random bit. At the least in the quantum version, each participant test whether
or not the other has attempted to create a bias on this bit. It is requested
that, for b = 0,1, the probability that Alice gets bit b and pass the test is
smaller than 1/2 whatever she does, and similarly for Bob. If the bound 1/2
holds perfectly against any of the two participants, the task realised is
called an exact coin tossing. If the bound is actually $1/2 + \xi$ where the
bias $\xi$ vanishes when a security parameter m defined by the protocol
increases, the task realised is a (non exact) coin tossing. It is found here
that exact coin tossing is impossible. At the same time, an unconditionally
secure quantum protocol that realises a (non exact) coin tossing is proposed.
The protocol executes m biased quantum coin tossing procedures at the same
time. It executes the first round in each of these m procedures sequentially,
then the second rounds are executed, and so on until the end of the n
procedures. Each procedure requires 4n particles where $n \in O(\lg m)$. The
final bit x is the parity of the m random bits. The information about each of
these m bits is announced a little bit at a time which implies that the
principle used against bit commitment does not apply. The bias on x is smaller
than $1/m$. The result is discussed in the light of the impossibility result
for exact coin tossing.
| [
{
"version": "v1",
"created": "Thu, 22 Apr 1999 22:43:38 GMT"
},
{
"version": "v2",
"created": "Tue, 27 Feb 2018 01:24:47 GMT"
}
] | 2018-02-28T00:00:00 | [
[
"Mayers",
"Dominic",
""
],
[
"Salvail",
"Louis",
""
],
[
"Chiba-Kohno",
"Yoshie",
""
]
] |
quant-ph/9904079 | Ronald de Wolf | Andris Ambainis (UC Berkeley) and Ronald de Wolf (CWI and U of
Amsterdam) | Average-Case Quantum Query Complexity | 14 pages, LaTeX. Some parts rewritten. This version to appear in the
Journal of Physics A | null | null | null | quant-ph cs.CC | null | We compare classical and quantum query complexities of total Boolean
functions. It is known that for worst-case complexity, the gap between quantum
and classical can be at most polynomial. We show that for average-case
complexity under the uniform distribution, quantum algorithms can be
exponentially faster than classical algorithms. Under non-uniform distributions
the gap can even be super-exponential. We also prove some general bounds for
average-case complexity and show that the average-case quantum complexity of
MAJORITY under the uniform distribution is nearly quadratically better than the
classical complexity.
| [
{
"version": "v1",
"created": "Fri, 23 Apr 1999 10:46:02 GMT"
},
{
"version": "v2",
"created": "Thu, 11 Nov 1999 09:48:25 GMT"
},
{
"version": "v3",
"created": "Mon, 2 Jul 2001 10:18:23 GMT"
}
] | 2009-09-25T00:00:00 | [
[
"Ambainis",
"Andris",
"",
"UC Berkeley"
],
[
"de Wolf",
"Ronald",
"",
"CWI and U of\n Amsterdam"
]
] |
quant-ph/9904080 | Piotr Garbaczewski | Piotr Garbaczewski | Noise perturbations in the Brownian motion and quantum dynamics | Phys. Lett. A, (1999), in press | Phys.Lett. A257 (1999) 31-36 | 10.1016/S0375-9601(99)00283-2 | null | quant-ph chao-dyn cond-mat nlin.CD | null | The third Newton law for mean velocity fields is utilised to generate
anomalous (enhanced) or non-dispersive diffusion-type processes which, in
particular, can be interpreted as a probabilistic counterpart of the
Schr\"{o}dinger picture quantum dynamics.
| [
{
"version": "v1",
"created": "Fri, 23 Apr 1999 13:22:24 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Garbaczewski",
"Piotr",
""
]
] |
quant-ph/9904081 | Ulrich Mohrhoff | Ulrich Mohrhoff | Quantum mechanics and elements of reality | 24 pages, plain TeX | null | null | SAAPS-99041 | quant-ph | null | It is widely accepted that a Born probability of 1 is sufficient for the
existence of a corresponding element of reality. Recently Vaidman has extended
this idea to the ABL probabilities of the time-symmetrized version of quantum
mechanics originated by Aharonov, Bergmann, and Lebowitz. Several authors have
objected to Vaidman's time-symmetrized elements of reality without casting
doubt on the widely accepted sufficiency condition for `ordinary' elements of
reality. In this paper I show that while the proper truth condition for a
quantum counterfactual is an ABL probability of 1, neither a Born probability
of 1 nor an ABL probability of 1 is sufficient for the existence of an element
of reality. The reason this is so is that the contingent properties of
quantum-mechanical systems are extrinsic. To obtain this result, I need to
discuss objective probabilities, retroactive causality, and the objectivity or
otherwise of the psychological arrow of time. One consequence of the extrinsic
nature of quantum-mechanical properties is that quantum mechanics presupposes
property-defining actual events (or states of affairs) and therefore cannot be
called upon to account for their occurrence (existence). Neither these events
nor the correlations between them are capable of explanation, the former
because they are causal primaries, the latter because they are fundamental:
there are no underlying causal processes. Causal connections are something we
project onto the statistical correlations, and this works only to the extent
that statistical variations can be ignored. There are nevertheless important
conclusions to be drawn from the quantum-mechanical correlations, such as the
spatial nonseparability of the world.
| [
{
"version": "v1",
"created": "Mon, 26 Apr 1999 03:00:20 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mohrhoff",
"Ulrich",
""
]
] |
quant-ph/9904082 | Paolo Facchi | P. Facchi and S. Pascazio | Berry phase due to quantum measurements | 6 pages, 2 figures. Contribution to the Sixth Central-European
Workshop on Quantum Optics, Chudobin near Olomouc, Czech Republic, April-May
1999 | Acta Phys.Slov. 49 (1999) 671-676 | null | null | quant-ph | null | The usual, "static" version of the quantum Zeno effect consists in the
hindrance of the evolution of a quantum systems due to repeated measurements.
There is however a "dynamic" version of the same phenomenon, first discussed by
von Neumann in 1932 and subsequently explored by Aharonov and Anandan, in which
a system is forced to follow a given trajectory. A Berry phase appears if such
a trajectory is a closed loop in the projective Hilbert space. A specific
example involving neutron spin is considered and a similar situation with
photon polarization is investigated.
| [
{
"version": "v1",
"created": "Sat, 24 Apr 1999 10:08:07 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Facchi",
"P.",
""
],
[
"Pascazio",
"S.",
""
]
] |
quant-ph/9904083 | Sayan Kar | Sayan Kar and Avinash Khare | Classical and quantum mechanics of a particle on a rotating loop | 30 pages, RevTex, 7 figures | Am.J.Phys. 68 (2000) 1128-1133 | 10.1119/1.1286427 | IOP Preprint, Physics Dept. and CTS, IITKgp Preprint | quant-ph | null | The toy model of a particle on a vertical rotating circle in the presence of
uniform gravitational/ magnetic fields is explored in detail. After an analysis
of the classical mechanics of the problem we then discuss the quantum mechanics
from both exact and semi--classical standpoints. Exact solutions of the
Schrodinger equation are obtained in some cases by diverse methods. Instantons,
bounces are constructed and semi-classical, leading order tunneling
amplitudes/decay rates are written down. We also investigate qualitatively the
nature of small oscillations about the kink/bounce solutions. Finally, the
connections of these toy examples with field theoretic and statistical
mechanical models of relevance are pointed out.
| [
{
"version": "v1",
"created": "Mon, 26 Apr 1999 04:41:59 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Kar",
"Sayan",
""
],
[
"Khare",
"Avinash",
""
]
] |
quant-ph/9904084 | Sergei Kozyrev | L.Accardi, S.V.Kozyrev, I.V.Volovich | Non-Exponential Decay for Polaron Model | Latex, 10 pages | Phys.Lett. A260 (1999) 31-38 | 10.1016/S0375-9601(99)00510-1 | SMI-26-04-99 | quant-ph | null | A model of particle interacting with quantum field is considered. The model
includes as particular cases the polaron model and non-relativistic quantum
electrodynamics. We compute matrix elements of the evolution operator in the
stochastic approximation and show that depending on the state of the particle
one can get the non-exponential decay with the rate t^{-3/2}. In the process of
computation a new algebra of commutational relations that can be considered as
an operator deformation of quantum Boltzmann commutation relations is used.
| [
{
"version": "v1",
"created": "Mon, 26 Apr 1999 09:46:51 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Accardi",
"L.",
""
],
[
"Kozyrev",
"S. V.",
""
],
[
"Volovich",
"I. V.",
""
]
] |
quant-ph/9904085 | Antonio Vidiella-Barranco | A.F. Gomes, J.A. Roversi, and A. Vidiella-Barranco (Universidade
Estadual de Campinas, Brazil) | Transfer of coherence from atoms to mixed field states in a two-photon
lossless micromaser | 20 pages, 8 figures, to appear in Journal of Modern Optics | J.Mod.Opt. 46 (1999) 1421 | 10.1080/09500349908231344 | null | quant-ph physics.atom-ph | null | We propose a two-photon micromaser-based scheme for the generation of a
nonclassical state from a mixed state. We conclude that a faster, as well as a
higher degree of field purity is achieved in comparison to one-photon
processes. We investigate the statistical properties of the resulting field
states, for initial thermal and (phase-diffused) coherent states.
Quasiprobabilities are employed to characterize the state of the generated
fields.
| [
{
"version": "v1",
"created": "Mon, 26 Apr 1999 14:43:57 GMT"
}
] | 2016-02-16T00:00:00 | [
[
"Gomes",
"A. F.",
"",
"Universidade\n Estadual de Campinas, Brazil"
],
[
"Roversi",
"J. A.",
"",
"Universidade\n Estadual de Campinas, Brazil"
],
[
"Vidiella-Barranco",
"A.",
"",
"Universidade\n Estadual de Campinas, Brazil"
]
] |
quant-ph/9904086 | Angelo Mariano | P. Facchi, A. Mariano, S. Pascazio | Wigner function and coherence properties of cold and thermal neutrons | 6 pages, 3 figures. Contribution to the Sixth Central-European
Workshop on Quantum Optics, Chudobin near Olomouc, Czech Republic, April-May
1999 | Acta Phys.Slov. 49 (1999) 677-682 | null | null | quant-ph | null | We analyze the coherence properties of a cold or a thermal neutron by
utilizing the Wigner quasidistribution function. We look in particular at a
recent experiment performed by Badurek {\em et al.}, in which a polarized
neutron crosses a magnetic field that is orthogonal to its spin, producing
highly non-classical states. The quantal coherence is extremely sensitive to
the field fluctuation at high neutron momenta. A "decoherence parameter" is
introduced in order to get quantitative estimates of the losses of coherence.
| [
{
"version": "v1",
"created": "Mon, 26 Apr 1999 10:01:20 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Facchi",
"P.",
""
],
[
"Mariano",
"A.",
""
],
[
"Pascazio",
"S.",
""
]
] |
quant-ph/9904087 | Sunish Menon | G. S. Agarwal | Control of Decoherence and Relaxation by Frequency Modulation of Heat
Bath | 5 text pages plus 3 figures. Submitted for publication in Phys. Rev.
Lett | null | 10.1103/PhysRevA.61.013809 | null | quant-ph | null | We demonstrate in a very general fashion, considerable slowing down of
decoherence and relaxation by fast frequency modulation of the system heat bath
coupling. The slowing occurs as the decoherence rates are now determined by the
spectral components of bath correlations which are shifted due to fast
modulation. We present several examples including the slowing down of the
heating of a trapped ion, where the system - bath interaction is not
necessarily Markovian.
| [
{
"version": "v1",
"created": "Mon, 26 Apr 1999 10:50:42 GMT"
}
] | 2021-05-26T00:00:00 | [
[
"Agarwal",
"G. S.",
""
]
] |
quant-ph/9904088 | A. K. Rajagopal | Sumiyoshi Abe(1) and A. K. Rajagopal(2) ((1)College of Science and
Technology, Nihon University, Funabashi, Chiba, Japan (2)Naval Research
Laboratory, Washington D.C., U.S.A) | Quantum entanglement inferred by the principle of maximum Tsallis
entropy | 15 pages, 1 figure | Phys.Rev. A60 (1999) 3461 | 10.1103/PhysRevA.60.3461 | null | quant-ph cond-mat.stat-mech | null | The problem of quantum state inference and the concept of quantum
entanglement are studied using a non-additive measure in the form of Tsallis
entropy indexed by the positive parameter q. The maximum entropy principle
associated with this entropy along with its thermodynamic interpretation are
discussed in detail for the Einstein-Podolosky-Rosen pair of two spin-1/2
particles. Given the data on the Bell-Clauser-Horne-Shimony-Holt observable,
the analytic expression is given for the inferred quantum entangled state. It
is shown that for q greater than unity, indicating the sub-additive feature of
the Tsalls entropy, the entangled region is small and enlarges as one goes into
super-additive regime where q is less than unity. It is also shown that quantum
entanglement can be quantified by the generalized Kullback-Leibler entropy.
| [
{
"version": "v1",
"created": "Mon, 26 Apr 1999 12:08:11 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Abe",
"Sumiyoshi",
""
],
[
"Rajagopal",
"A. K.",
""
]
] |
quant-ph/9904089 | Konrad Banaszek | K. Banaszek, C. Radzewicz, K. Wodkiewicz, J. S. Krasinski | Determination of the Wigner function from photon statistics | 4 pages LaTeX, contribution to proceedings of 6th central-european
workshop on quantum optics; see also
http://www.fuw.edu.pl/~kbanasz/QOLab/ExpWigner/ | Acta Phys.Slov. 49 (1999) 643-646 | null | null | quant-ph | null | We present an experimental realisation of the direct scheme for measuring the
Wigner function of a single quantized light mode. In this method, the Wigner
function is determined as the expectation value of the photon number parity
operator for the phase space displaced quantum state.
| [
{
"version": "v1",
"created": "Mon, 26 Apr 1999 14:07:52 GMT"
},
{
"version": "v2",
"created": "Tue, 27 Apr 1999 07:42:23 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Banaszek",
"K.",
""
],
[
"Radzewicz",
"C.",
""
],
[
"Wodkiewicz",
"K.",
""
],
[
"Krasinski",
"J. S.",
""
]
] |
quant-ph/9904090 | Boris F. Samsonov | Boris F. Samsonov | Coherent States for Transparent Potentials | null | J.Phys.A33:591-605,2000 | 10.1088/0305-4470/33/3/312 | null | quant-ph | null | Darboux transformation operators that produce multisoliton potentials are
analyzed as operators acting in a Hilbert space. Isometric correspondence
between Hilbert spaces of states of a free particle and a particle moving in a
soliton potential is established. It is shown that the Darboux transformation
operator is unbounded but closed and can not realize an isometric mapping
between Hilbert spaces. A quasispectral representation of such an operator in
terms of continuum bases is obtained. Different types of coherent states of a
multisoliton potential are introduced. Measures that realize the resolution of
the identity operator in terms of the projectors on the coherent states vectors
are calculated. It is shown that when these states are related with free
particle coherent states by a bounded symmetry operator the measure is defined
by ordinary functions and in the case of a semibounded symmetry operator the
measure is defined by a generalized function.
| [
{
"version": "v1",
"created": "Tue, 27 Apr 1999 03:17:21 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Samsonov",
"Boris F.",
""
]
] |
quant-ph/9904091 | Hoi-Kwong Lo | Hoi-Kwong Lo (Hewlett-Packard Labs, Bristol) | A simple proof of the unconditional security of quantum key distribution | 13 pages, extended abstract. Comments will be appreciated | J.Phys.A34:6957-6968,2001 | 10.1088/0305-4470/34/35/321 | null | quant-ph cs.CR | null | Quantum key distribution is the most well-known application of quantum
cryptography. Previous proposed proofs of security of quantum key distribution
contain various technical subtleties. Here, a conceptually simpler proof of
security of quantum key distribution is presented. The new insight is the
invariance of the error rate of a teleportation channel: We show that the error
rate of a teleportation channel is independent of the signals being
transmitted. This is because the non-trivial error patterns are permuted under
teleportation. This new insight is combined with the recently proposed quantum
to classical reduction theorem. Our result shows that assuming that Alice and
Bob have fault-tolerant quantum computers, quantum key distribution can be made
unconditionally secure over arbitrarily long distances even against the most
general type of eavesdropping attacks and in the presence of all types of
noises.
| [
{
"version": "v1",
"created": "Tue, 27 Apr 1999 08:49:27 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Lo",
"Hoi-Kwong",
"",
"Hewlett-Packard Labs, Bristol"
]
] |
quant-ph/9904092 | Michal Horodecki | Pawel Horodecki, Michal Horodecki and Ryszard Horodecki | Binding entanglement channels | RevTeX, 5 pages, submitted to special issue of J. Mod. Opt | J.Mod.Opt. 47 (2000) 347-354 | 10.1080/09500340008244047 | null | quant-ph | null | We define the binding entanglement channel as the quantum channel through
which quantum information cannot be reliably transmitted, but which can be used
to share bound entanglement. We provide a characterization of such class of
channels. We also show that any bound entangled state can be used to
construction of the map corresponding the binding entanglement channel.
| [
{
"version": "v1",
"created": "Tue, 27 Apr 1999 16:14:53 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Horodecki",
"Pawel",
""
],
[
"Horodecki",
"Michal",
""
],
[
"Horodecki",
"Ryszard",
""
]
] |
quant-ph/9904093 | Ashwin Nayak | Ashwin Nayak | Optimal lower bounds for quantum automata and random access codes | 8 pages, 1 figure, Latex2e. Extensive modifications have been made to
increase clarity. To appear in FOCS'99 | null | null | null | quant-ph cs.CC | null | Consider the finite regular language L_n = {w0 : w \in {0,1}^*, |w| \le n}.
It was shown by Ambainis, Nayak, Ta-Shma and Vazirani that while this language
is accepted by a deterministic finite automaton of size O(n), any one-way
quantum finite automaton (QFA) for it has size 2^{Omega(n/log n)}. This was
based on the fact that the evolution of a QFA is required to be reversible.
When arbitrary intermediate measurements are allowed, this intuition breaks
down. Nonetheless, we show a 2^{Omega(n)} lower bound for such QFA for L_n,
thus also improving the previous bound. The improved bound is obtained by
simple entropy arguments based on Holevo's theorem. This method also allows us
to obtain an asymptotically optimal (1-H(p))n bound for the dense quantum codes
(random access codes) introduced by Ambainis et al. We then turn to Holevo's
theorem, and show that in typical situations, it may be replaced by a tighter
and more transparent in-probability bound.
| [
{
"version": "v1",
"created": "Tue, 27 Apr 1999 23:59:48 GMT"
},
{
"version": "v2",
"created": "Wed, 28 Apr 1999 00:00:48 GMT"
},
{
"version": "v3",
"created": "Tue, 7 Sep 1999 23:04:01 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Nayak",
"Ashwin",
""
]
] |
quant-ph/9904094 | Thomas Thiemann | A. Ashtekar, D. Marolf, J. Mour\~ao, T. Thiemann | Constructing Hamiltonian quantum theories from path integrals in a
diffeomorphism invariant context | Plain Latex, 25 p., references added, abstract and title changed
(originally :``Osterwalder Schrader Reconstruction and Diffeomorphism
Invariance''), introduction extended, one appendix with illustrative model
added, accepted by Class. Quantum Grav | Class.Quant.Grav. 17 (2000) 4919-4940 | 10.1088/0264-9381/17/23/310 | AEI-109 | quant-ph gr-qc hep-th | null | Osterwalder and Schrader introduced a procedure to obtain a (Lorentzian)
Hamiltonian quantum theory starting from a measure on the space of (Euclidean)
histories of a scalar quantum field. In this paper, we extend that construction
to more general theories which do not refer to any background, space-time
metric (and in which the space of histories does not admit a natural linear
structure). Examples include certain gauge theories, topological field theories
and relativistic gravitational theories. The treatment is self-contained in the
sense that an a priori knowledge of the Osterwalder-Schrader theorem is not
assumed.
| [
{
"version": "v1",
"created": "Wed, 28 Apr 1999 06:24:43 GMT"
},
{
"version": "v2",
"created": "Fri, 1 Dec 2000 17:18:12 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Ashtekar",
"A.",
""
],
[
"Marolf",
"D.",
""
],
[
"Mourão",
"J.",
""
],
[
"Thiemann",
"T.",
""
]
] |
quant-ph/9904095 | Stefan Weigert | Stefan Weigert | A Discrete Phase-Space Calculus for Quantum Spins based on a
Reconstruction Method using Coherent States | Latex2e, 9 pages | null | null | null | quant-ph | null | To reconstruct a mixed or pure quantum state of a spin s is possible through
coherent states: its density matrix is fixed by the probabilities to measure
the value s along 4s(s+1) appropriately chosen directions in space. Thus, after
inverting the experimental data, the statistical operator is parametrized
entirely by expectation values. On this basis, a symbolic calculus for quantum
spins is developed, the `expectation-value representation.' It resembles the
Moyal representation for SU(2) but two important differences exist. On the one
hand, the symbols take values on a discrete set of points in phase space only.
On the other hand, no quasi-probabilities - that is, phase-space distributions
with negative values - are encountered in this approach.
| [
{
"version": "v1",
"created": "Wed, 28 Apr 1999 12:23:39 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Weigert",
"Stefan",
""
]
] |
quant-ph/9904096 | Atac Imamoglu | A. Imamoglu, D. D. Awschalom, G. Burkard, D. P. DiVincenzo, D. Loss,
M. Sherwin, A. Small | Quantum information processing using quantum dot spins and cavity-QED | Revised version including a method to realize parallel two-qubit
operations | null | null | null | quant-ph cond-mat.mes-hall | null | The electronic spin degrees of freedom in semiconductors typically have
decoherence times that are several orders of magnitude longer than other
relevant timescales. A solid-state quantum computer based on localized electron
spins as qubits is therefore of potential interest. Here, a scheme that
realizes controlled interactions between two distant quantum dot spins is
proposed. The effective long-range interaction is mediated by the vacuum field
of a high finesse microcavity. By using conduction-band-hole Raman transitions
induced by classical laser fields and the cavity-mode, parallel controlled-not
operations and arbitrary single qubit rotations can be realized. Optical
techniques can also be used to measure the spin-state of each quantum dot.
| [
{
"version": "v1",
"created": "Wed, 28 Apr 1999 18:03:53 GMT"
},
{
"version": "v2",
"created": "Thu, 15 Jul 1999 19:07:05 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Imamoglu",
"A.",
""
],
[
"Awschalom",
"D. D.",
""
],
[
"Burkard",
"G.",
""
],
[
"DiVincenzo",
"D. P.",
""
],
[
"Loss",
"D.",
""
],
[
"Sherwin",
"M.",
""
],
[
"Small",
"A.",
""
]
] |
quant-ph/9904097 | Constantin Brif | C. Brif and A. Mann | Testing Bell's inequality with two-level atoms via population
spectroscopy | 4 pages, REVTeX, no figures. More info on
http://www.ligo.caltech.edu/~cbrif/science.html | Europhys.Lett.49:1-7,2000 | 10.1209/epl/i2000-00111-0 | null | quant-ph | null | We propose a feasible experimental scheme, employing methods of population
spectroscopy with two-level atoms, for a test of Bell's inequality for massive
particles. The correlation function measured in this scheme is the joint atomic
$Q$ function. An inequality imposed by local realism is violated by any
entangled state of a pair of atoms.
| [
{
"version": "v1",
"created": "Wed, 28 Apr 1999 19:48:06 GMT"
}
] | 2010-12-17T00:00:00 | [
[
"Brif",
"C.",
""
],
[
"Mann",
"A.",
""
]
] |
quant-ph/9904098 | Aephraim M. Steinberg | A. M. Steinberg (Univ. of Toronto) | On energy transfer by detection of a tunneling atom | 5 pages, 2 figures | J.KoreanPhys.Soc.35:122-126,1999 | null | null | quant-ph | null | We are in the process of building an experiment to study the tunneling of
laser-cooled Rubidium atoms through an optical barrier. A particularly thorny
set of questions arises when one considers the possibility of observing a
tunneling particle while it is in the ``forbidden'' region. In earlier work, we
have discussed how one might probe a tunneling atom ``weakly,'' so as to
prevent collapse. Here we make some observations about the implications of a
more traditional quantum measurement. Considerations of energy conservation
suggest that attempts to observe tunneling atoms will enhance inelastic
scattering, but not in a way which can be directly observed. It is possible
that attempts to make such measurements may lead to experimentally realizable
``observationally assisted barrier penetration.''
| [
{
"version": "v1",
"created": "Wed, 28 Apr 1999 21:52:19 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Steinberg",
"A. M.",
"",
"Univ. of Toronto"
]
] |
quant-ph/9904099 | Michael Werner | M.J. Werner | Quantum soliton generation using an interferometer | 7 pages, 3 figures | Phys.Rev.Lett. 81 (1998) 4132-4135 | 10.1103/PhysRevLett.81.4132 | null | quant-ph | null | For the first time a method for realizing macroscopic quantum optical
solitons is presented. Simultaneous photon-number and momentum squeezing is
predicted using soliton propagation in an interferometer. Extraction of soliton
pulses closer to true quantum solitons than their coherent counterparts from
mode-locked lasers is possible. Moreover, it is a general method of reducing
photon-number fluctuations below the shot-noise level for non-soliton pulses as
well. It is anticipated that similar reductions in particle fluctuations could
occur for other forms of interfering bosonic fields whenever self-interaction
nonlinearities exist, for example, interacting ultracold atoms.
| [
{
"version": "v1",
"created": "Wed, 28 Apr 1999 23:04:31 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Werner",
"M. J.",
""
]
] |
quant-ph/9904100 | Debbie Leung | Debbie W. Leung (1,2), Isaac L. Chuang (2), Fumiko Yamaguchi (1) and
Yoshihisa Yamamoto (1,3) ((1) Stanford University (2) IBM Almaden Research
Center (3) NTT Basic Research Laboratories) | Efficient implementation of selective recoupling in heteronuclear spin
systems using Hadamard matrices | 7 pages, 4 figures, mypsfig2, revtex, submitted April 27, 1999 | Phys.Rev.A61:042310,2000 | 10.1103/PhysRevA.61.042310 | null | quant-ph | null | We present an efficient scheme which couples any designated pair of spins in
heteronuclear spin systems. The scheme is based on the existence of Hadamard
matrices. For a system of $n$ spins with pairwise coupling, the scheme
concatenates $cn$ intervals of system evolution and uses at most $c n^2$ pulses
where $c \approx 1$. Our results demonstrate that, in many systems, selective
recoupling is possible with linear overhead, contrary to common speculation
that exponential effort is always required.
| [
{
"version": "v1",
"created": "Wed, 28 Apr 1999 23:57:39 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Leung",
"Debbie W.",
""
],
[
"Chuang",
"Isaac L.",
""
],
[
"Yamaguchi",
"Fumiko",
""
],
[
"Yamamoto",
"Yoshihisa",
""
]
] |
quant-ph/9904101 | Paul Slater | Paul B. Slater (University of California) | Hall Normalization Constants for the Bures Volumes of the n-State
Quantum Systems | 14 pages, LaTeX, 6 postscript figures. Revised version to appear in
J. Phys. A. We make a few slight changes from the previous version, but also
add a subsection (III G) in which several variations of the basic problem are
newly studied. Rather strong evidence is adduced that the Hall constants are
related to partial sums of denominators of the even-indexed Bernoulli
numbers, although a general formula is still lacking | J.Phys.A32:8231-8246,1999 | 10.1088/0305-4470/32/47/303 | null | quant-ph math-ph math.MP | null | We report the results of certain integrations of quantum-theoretic interest,
relying, in this regard, upon recently developed parameterizations of Boya et
al of the n x n density matrices, in terms of squared components of the unit
(n-1)-sphere and the n x n unitary matrices. Firstly, we express the normalized
volume elements of the Bures (minimal monotone) metric for n = 2 and 3,
obtaining thereby "Bures prior probability distributions" over the two- and
three-state systems. Then, as an essential first step in extending these
results to n > 3, we determine that the "Hall normalization constant" (C_{n})
for the marginal Bures prior probability distribution over the
(n-1)-dimensional simplex of the n eigenvalues of the n x n density matrices
is, for n = 4, equal to 71680/pi^2. Since we also find that C_{3} = 35/pi, it
follows that C_{4} is simply equal to 2^{11} C_{3}/pi. (C_{2} itself is known
to equal 2/pi.) The constant C_{5} is also found. It too is associated with a
remarkably simple decompositon, involving the product of the eight consecutive
prime numbers from 2 to 23.
We also preliminarily investigate several cases, n > 5, with the use of
quasi-Monte Carlo integration. We hope that the various analyses reported will
prove useful in deriving a general formula (which evidence suggests will
involve the Bernoulli numbers) for the Hall normalization constant for
arbitrary n. This would have diverse applications, including quantum inference
and universal quantum coding.
| [
{
"version": "v1",
"created": "Thu, 29 Apr 1999 20:15:42 GMT"
},
{
"version": "v2",
"created": "Fri, 7 May 1999 20:23:30 GMT"
},
{
"version": "v3",
"created": "Sat, 8 May 1999 20:45:38 GMT"
},
{
"version": "v4",
"created": "Thu, 1 Jul 1999 17:25:42 GMT"
},
{
"version": "v5",
"created": "Thu, 7 Oct 1999 20:19:24 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Slater",
"Paul B.",
"",
"University of California"
]
] |
quant-ph/9904102 | Adrian Alscher | Adrian Alscher and Hermann Grabert | Semiclassical dynamics of a spin-1/2 in an arbitrary magnetic field | 16 pages, submitted to Journal of Physics A | J.Phys.A32:4907-4919,1999 | 10.1088/0305-4470/32/26/309 | null | quant-ph math-ph math.MP | null | The spin coherent state path integral describing the dynamics of a
spin-1/2-system in a magnetic field of arbitrary time-dependence is considered.
Defining the path integral as the limit of a Wiener regularized expression, the
semiclassical approximation leads to a continuous minimal action path with
jumps at the endpoints. The resulting semiclassical propagator is shown to
coincide with the exact quantum mechanical propagator. A non-linear
transformation of the angle variables allows for a determination of the
semiclassical path and the jumps without solving a boundary-value problem. The
semiclassical spin dynamics is thus readily amenable to numerical methods.
| [
{
"version": "v1",
"created": "Thu, 29 Apr 1999 18:17:12 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Alscher",
"Adrian",
""
],
[
"Grabert",
"Hermann",
""
]
] |
quant-ph/9904103 | Adrian Alscher | Joachim Hainz and Hermann Grabert | Centrifugal terms in the WKB approximation and semiclassical
quantization of hydrogen | 5 pages, to appear in Phys. Rev. A | null | 10.1103/PhysRevA.60.1698 | null | quant-ph physics.atom-ph | null | A systematic semiclassical expansion of the hydrogen problem about the
classical Kepler problem is shown to yield remarkably accurate results. Ad hoc
changes of the centrifugal term, such as the standard Langer modification where
the factor l(l+1) is replaced by (l+1/2)^2, are avoided. The semiclassical
energy levels are shown to be exact to first order in $\hbar$ with all higher
order contributions vanishing. The wave functions and dipole matrix elements
are also discussed.
| [
{
"version": "v1",
"created": "Thu, 29 Apr 1999 18:31:41 GMT"
},
{
"version": "v2",
"created": "Fri, 30 Apr 1999 09:17:49 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Hainz",
"Joachim",
""
],
[
"Grabert",
"Hermann",
""
]
] |
quant-ph/9904104 | Michael Werner | M. J. Werner and S. R. Friberg | Phase transitions and the internal noise structure of nonlinear
Schr\"odi nger equation solitons | 10 pages, 5 figures | Phys.Rev.Lett. 79 (1997) 4143-4146 | 10.1103/PhysRevLett.79.4143 | null | quant-ph | null | We predict phase-transitions in the quantum noise characteristics of systems
described by the quantum nonlinear Schr\"odinger equation, showing them to be
related to the solitonic field transition at half the fundamental soliton
amplitude. These phase-transitions are robust with respect to Raman noise and
scattering losses. We also describe the rich internal quantum noise structure
of the solitonic fields in the vicinity of the phase-transition. For optical
coherent quantum solitons, this leads to the prediction that eliminating the
peak side-band noise due to the electronic nonlinearity of silica fiber by
spectral filtering leads to the optimal photon-number noise reduction of a
fundamental soliton.
| [
{
"version": "v1",
"created": "Thu, 29 Apr 1999 19:17:29 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Werner",
"M. J.",
""
],
[
"Friberg",
"S. R.",
""
]
] |
quant-ph/9904105 | Gennady Berman | G.P. Berman, G.D. Doolen, and V.I. Tsifrinovich | Quantum Computation as a Dynamical Process | 13 pages, 1 column, no figures | Comput.Phys.Commun.127:91-99,2000 | 10.1016/S0010-4655(00)00031-X | null | quant-ph | null | In this paper, we discuss the dynamical issues of quantum computation. We
demonstrate that fast wave function oscillations can affect the performance of
Shor's quantum algorithm by destroying required quantum interference. We also
show that this destructive effect can be routinely avoided by using
resonant-pulse techniques. We discuss the dynamics of resonant pulse
implementations of quantum logic gates in Ising spin systems. We also discuss
the influence of non-resonant excitations. We calculate the range of parameters
where undesirable non-resonant effects can be minimized. Finally, we describe
the ``$2\pi k$-method'' which avoids the detrimental deflection of non-resonant
qubits.
| [
{
"version": "v1",
"created": "Thu, 29 Apr 1999 20:30:11 GMT"
}
] | 2011-04-15T00:00:00 | [
[
"Berman",
"G. P.",
""
],
[
"Doolen",
"G. D.",
""
],
[
"Tsifrinovich",
"V. I.",
""
]
] |
quant-ph/9904106 | Dan Solomon | Dan Solomon | Mathematical Inconsistencies in Dirac Field Theory | 44 pages | null | null | null | quant-ph | null | If a mathematical theory contains incompatible postulates then it is likely
that the theory will produce theorems or results that are contradictory. It
will be shown that this is the case with Dirac field theory. An example of such
a contradiction is the problem asociated with evaluating the Schwinger term. It
is generally known that different ways of evaluating this quantity yield
different results. It will be shown that the reason for this is that Dirac
field theory is mathematically inconsistent, i.e., it contains incompatible
assumptions or postulates. The generally accepted definition of the vacuum
state must be modified in order to create a consistent theory.
| [
{
"version": "v1",
"created": "Thu, 29 Apr 1999 20:35:51 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Solomon",
"Dan",
""
]
] |
quant-ph/9904107 | Yaoyun Shi | Yaoyun Shi (Princeton University) | Lower bounds of quantum black-box complexity and degree of approximation
polynomials by influence of Boolean variables | 12 pages, LaTex, minor changes | IPL, 75(1-2):79--83, July 2000. | null | null | quant-ph | null | We prove that, to compute a Boolean function $f$ on $N$ variables with error
probability $\epsilon$, any quantum black-box algorithm has to query at least
$\frac{1 - 2\sqrt{\epsilon}}{2} \rho_f N = \frac{1 - 2\sqrt{\epsilon}}{2}
\bar{S}_f$ times, where $\rho_f$ is the average influence of variables in $f$,
and $\bar{S}_f$ is the average sensitivity. It's interesting to contrast this
result with the known lower bound of $\Omega (\sqrt{S_f})$, where $S_f$ is the
sensitivity of $f$. This lower bound is tight for some functions. We also show
for any polynomial $\tilde{f}$ that approximates $f$ with error probability
$\epsilon$, $deg(\tilde{f}) \ge 1/4 (1 - \frac{3 \epsilon}{1 + \epsilon})^2
\rho_f N$. This bound can be better than previous known lower bound of
$\Omega(\sqrt{BS_f})$ for some functions. Our technique may be of intest
itself: we apply Fourier analysis to functions mapping $\{0, 1\}^N$ to unit
vectors in a Hilbert space. From this viewpoint, the state of the quantum
computer at step $t$ can be written as $\sum_{s\in \{0, 1\}^N, |s| \le t}
\hat{\phi}_s (-1)^ {s \cdot x}$, which is handy for lower bound analysis.
| [
{
"version": "v1",
"created": "Thu, 29 Apr 1999 21:25:48 GMT"
},
{
"version": "v2",
"created": "Sat, 8 May 1999 00:56:34 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Shi",
"Yaoyun",
"",
"Princeton University"
]
] |
quant-ph/9904108 | Wim van Dam | Wim van Dam (1,2) and Frederic Magniez (3) and Michele Mosca (2,4) and
Miklos Santha (3,5) ((1) CWI Amsterdam (2) CQC Oxford (3) LRI Paris Sud (4) U
of Waterloo (5) CNRS) | Self-Testing of Universal and Fault-Tolerant Sets of Quantum Gates | LaTeX2e, 14 pages, no figures, usepackage{a4wide,amssymb,amsmath};
major changes (Feb 2000), results expanded to 2-qubit gates. To appear in
Proceedings of the 32nd Annual ACM Symposium on Theory of Computing | Proceedings of the 32nd Annual ACM Symposium on Theory of
Computing (STOC2000), pages 688-696 | 10.1145/335305.335402 | null | quant-ph cs.OH | null | We consider the design of self-testers for quantum gates. A self-tester for
the gates F_1,...,F_m is a classical procedure that, given any gates
G_1,...,G_m, decides with high probability if each G_i is close to F_i. This
decision has to rely only on measuring in the computational basis the effect of
iterating the gates on the classical states. It turns out that instead of
individual gates, we can only design procedures for families of gates. To
achieve our goal we borrow some elegant ideas of the theory of program testing:
we characterize the gate families by specific properties, we develop a theory
of robustness for them, and show that they lead to self-testers. In particular
we prove that the universal and fault-tolerant set of gates consisting of a
Hadamard gate, a c-NOT gate, and a phase rotation gate of angle pi/4 is
self-testable.
| [
{
"version": "v1",
"created": "Thu, 29 Apr 1999 22:06:49 GMT"
},
{
"version": "v2",
"created": "Sun, 13 Feb 2000 21:09:33 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"van Dam",
"Wim",
""
],
[
"Magniez",
"Frederic",
""
],
[
"Mosca",
"Michele",
""
],
[
"Santha",
"Miklos",
""
]
] |
quant-ph/9904109 | Ruediger Schack | R. Schack (Royal Holloway, University of London), C. M. Caves
(University of New Mexico) | Explicit product ensembles for separable quantum states | 15 pages, no figures | J.Mod.Opt. 47 (2000) 387-399 | 10.1080/09500340008244050 | null | quant-ph | null | We present a general method for constructing pure-product-state
representations for density operators of $N$ quantum bits. If such a
representation has nonnegative expansion coefficients, it provides an explicit
separable ensemble for the density operator. We derive the condition for
separability of a mixture of the Greenberger-Horne-Zeilinger state with the
maximally mixed state.
| [
{
"version": "v1",
"created": "Fri, 30 Apr 1999 14:29:56 GMT"
},
{
"version": "v2",
"created": "Wed, 19 May 1999 08:32:48 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Schack",
"R.",
"",
"Royal Holloway, University of London"
],
[
"Caves",
"C. M.",
"",
"University of New Mexico"
]
] |
quant-ph/9904110 | M. Czachor | Marek Czachor, Maciej Kuna, Sergiej B. Leble, and Jan Naudts | Nonlinear von Neumann-type equations | To be published in "New insights in quantum mechanics", H.D. Doebner,
S.T. Ali, M. Keyl, and R.F. Werner, eds. (World Scientific, 1999); 3 eps
figures, style goslar.cls included | null | null | null | quant-ph nlin.SI solv-int | null | We review some recent developments in the theory of nonlinear von Neumann
equations. We distinguish between the von Neumann equation (which can be
nonlinear) and the Liouville equation (which should be linear). Explicit
examples illustrate the technique of binary Darboux integration of nonlinear
density matrix equations and special attention is payed to the problem of how
to find physically nontrivial `self-scattering' solutions.
| [
{
"version": "v1",
"created": "Fri, 30 Apr 1999 18:07:14 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Czachor",
"Marek",
""
],
[
"Kuna",
"Maciej",
""
],
[
"Leble",
"Sergiej B.",
""
],
[
"Naudts",
"Jan",
""
]
] |
quant-ph/9905001 | Chiao | Raymond Y. Chiao and Jack Boyce (Dept. of Physics, University of
California, Berkeley, California) | Bogoliubov dispersion relation and the possibility of superfluidity for
weakly-interacting photons in a 2D photon fluid | 11 pages, 4 figures, REVTEX style, to be published in PRA, Nov. 1,
1999 | null | 10.1103/PhysRevA.60.4114 | null | quant-ph cond-mat | null | The Bogoliubov dispersion relation for the elementary excitations of the
weakly-interacting Bose gas is shown to hold for the case of the
weakly-interacting photon gas (the ``photon fluid'') in a nonlinear Fabry-Perot
cavity. This relation, which is also derived by means of a linearized
fluctuation analysis in classical nonlinear optics, implies the possibility of
a new superfluid state of light. The theory underlying an experiment in
progress to measure this dispersion relation is described, and another
experiment to test the prediction of the superfluidity of this state of light
is proposed.
| [
{
"version": "v1",
"created": "Sat, 1 May 1999 00:38:57 GMT"
},
{
"version": "v2",
"created": "Thu, 22 Jul 1999 01:24:05 GMT"
},
{
"version": "v3",
"created": "Tue, 12 Oct 1999 02:12:56 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Chiao",
"Raymond Y.",
"",
"Dept. of Physics, University of\n California, Berkeley, California"
],
[
"Boyce",
"Jack",
"",
"Dept. of Physics, University of\n California, Berkeley, California"
]
] |
quant-ph/9905002 | E. D. Davis | E. D. Davis, G. I. Ghandour | Implications of invariance of the Hamiltonian under canonical
transformations in phase space | REVTeX v3.1, 13 pages | J.Phys.A35:5875-5891,2002 | 10.1088/0305-4470/35/28/307 | null | quant-ph | null | We observe that, within the effective generating function formalism for the
implementation of canonical transformations within wave mechanics, non-trivial
canonical transformations which leave invariant the form of the Hamilton
function of the classical analogue of a quantum system manifest themselves in
an integral equation for its stationary state eigenfunctions. We restrict
ourselves to that subclass of these dynamical symmetries for which the
corresponding effective generating functions are necessaarily free of quantum
corrections. We demonstrate that infinite families of such transformations
exist for a variety of familiar conservative systems of one degree of freedom.
We show how the geometry of the canonical transformations and the symmetry of
the effective generating function can be exploited to pin down the precise form
of the integral equations for stationary state eigenfunctions. We recover
several integral equations found in the literature on standard special
functions of mathematical physics. We end with a brief discussion (relevant to
string theory) of the generalization to scalar field theories in 1+1
dimensions.
| [
{
"version": "v1",
"created": "Mon, 3 May 1999 11:52:13 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Davis",
"E. D.",
""
],
[
"Ghandour",
"G. I.",
""
]
] |
quant-ph/9905003 | David Marcus Appleby | D. M. Appleby | Generic Bohmian Trajectories of an Isolated Particle | 16 pages, 5 figures, AMS-latex. Argument condensed. No changes to
content | Found.Phys.29:1863-1916,1999 | 10.1023/A:1018842401049 | QMW-PH-99-06 | quant-ph | null | The generic Bohmian trajectories are calculated for an isolated particle in
an approximate energy eigenstate, for an arbitrary one-dimensional potential
well. It is shown, that the necessary and sufficient condition for there to be
a negligible probability of the trajectory deviating significantly from the
classical trajectory at any stage in the motion is, that the state be a
narrowly localised wave packet. The properties of the Bohmian trajectories are
discussed in relationship to the theory of retrodictively optimal simultaneous
measurements of position and momentum which was presented in several previous
papers. It is shown that the Bohmian velocity at x is the expectation value of
the velocity which would be observed at x, if one were to make a retrodictively
optimal simultaneous measurement of x and p, in the limit as the error in the
measurement of x tends to zero. This explains the tendency of the Bohmian
particle to behave in a highly non-classical manner. It also explains why the
trajectories in the interpretation recently proposed by Garcia de Polavieja
tend to be much more nearly classical in the limit of large quantum number. The
implications for other trajectory interpretations are considered.
| [
{
"version": "v1",
"created": "Mon, 3 May 1999 23:20:05 GMT"
},
{
"version": "v2",
"created": "Sun, 8 Aug 1999 22:46:25 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Appleby",
"D. M.",
""
]
] |
quant-ph/9905004 | H. Dieter Zeh | H. D. Zeh | The Meaning of Decoherence | 25 pages, Latex, needs Springer macro cl2emult. Version to be
published. An error in the comments regarding the relation between Bloch
vectors and Wigner functions has been eliminated (see Footnote 3) | Lect.Notes Phys. 538 (2000) 19-42 | null | null | quant-ph cond-mat math-ph math.MP physics.atom-ph physics.chem-ph | null | The conceptual and dynamical aspects of decoherence are analyzed, while their
consequences are discussed for several fundamental applications. This
mechanism, which is based on a universal Schr\"odinger equation, is furthermore
compared with the phenomenological description of open systems in terms of
`quantum dynamical maps'.
| [
{
"version": "v1",
"created": "Tue, 4 May 1999 14:27:20 GMT"
},
{
"version": "v2",
"created": "Tue, 29 Jun 1999 13:27:22 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Zeh",
"H. D.",
""
]
] |
quant-ph/9905005 | Liu Yuxi | Chang-qi Cao, Liu Yu-Xi and Hui Cao | The exact solution for the superfluorescence of low density Frenkel
excitons in double and triple lattice-layers | 10 pages no figure. submitted to Phys. Rev. B | null | null | null | quant-ph | null | In low density regime, the fluorescence of Frenkel exitons in crystal slab
can be studied without the aid of rotating wave and Mackoffian approximation.
The equations for the case of double and triple lattice-layers are now solved
exactly to give the eigen decay rates, frequency shifts and the statistical
properties of the fields.
| [
{
"version": "v1",
"created": "Tue, 4 May 1999 05:18:01 GMT"
},
{
"version": "v2",
"created": "Thu, 6 May 1999 01:40:35 GMT"
},
{
"version": "v3",
"created": "Wed, 26 Jan 2000 03:13:27 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Cao",
"Chang-qi",
""
],
[
"Yu-Xi",
"Liu",
""
],
[
"Cao",
"Hui",
""
]
] |
quant-ph/9905006 | Ting Yu | Ting Yu, Lajos Diosi, Nicolas Gisin, and Walter T. Strunz | Post-Markov master equation for the dynamics of open quantum systems | 7 pages, 2 figures, RevTex | Phys.Lett. A265 (2000) 331-336 | 10.1016/S0375-9601(00)00014-1 | null | quant-ph cond-mat.stat-mech | null | A systematic first-order correction to the standard Markov master equation
for open quantum systems interacting with a bosonic bath is presented. It
extends the Markov Lindblad master equation to the more general case of
non-Markovian evolution. The meaning and applications of our `post'-Markov
master equation are illustrated with several examples, including a damped
two-level atom, the spin-boson model and the quantum Brownian motion model.
Limitations of the Markov approximation, the problem of positivity violation
and initial slips are also discussed.
| [
{
"version": "v1",
"created": "Tue, 4 May 1999 09:20:36 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Yu",
"Ting",
""
],
[
"Diosi",
"Lajos",
""
],
[
"Gisin",
"Nicolas",
""
],
[
"Strunz",
"Walter T.",
""
]
] |
quant-ph/9905007 | Stefan Scheel | Stefan Scheel, Ludwig Knoell, Dirk-Gunnar Welsch | Spontaneous decay in the presence of absorbing dielectric bodies | 10 pages LaTeX, 8 Postscript figures, contribution to proceedings of
the 6th central-european workshop on quantum optics (adacta.sty included) | null | null | null | quant-ph | null | We present a formalism for studying the influence of dispersive and absorbing
dielectric bodies on a radiating atom in the framework of quantization of the
phenomenological Maxwell equations for given complex permittivities of the
bodies. In Markov approximation, the rate of spontaneous decay and the line
shift associated with it can then be related to the complex permittivities and
geometries of the bodies via the dyadic Green function of the classical
boundary value problem of electrodynamics -- a result which is in agreement
with second-order calculations for microscopic model systems. The theory is
applied to an atom near a planar interface as well as to an atom in a spherical
cavity. The latter, also known as the real-cavity model for spontaneous decay
of an excited atom embedded in a dielectric, is compared with the
virtual-cavity model. Connections with other approaches are mentioned and the
results are compared.
| [
{
"version": "v1",
"created": "Tue, 4 May 1999 10:22:24 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Scheel",
"Stefan",
""
],
[
"Knoell",
"Ludwig",
""
],
[
"Welsch",
"Dirk-Gunnar",
""
]
] |
quant-ph/9905008 | Jonathan A. Jones | J. A. Jones and E. Knill | Efficient Refocussing of One Spin and Two Spin Interactions for NMR
Quantum Computation | 4 pages, RevTeX, including 4 LaTeX figures | J.Magn.Resonance 141 (1999) 322-325 | 10.1006/jmre.1999.1890 | JAJQP-99-01 | quant-ph | null | The use of spin echoes to refocus one spin interactions (chemical shifts) and
two spin interactions (spin-spin couplings) plays a central role in both
conventional NMR experiments and NMR quantum computation. Here we describe
schemes for efficient refocussing of such interactions in both fully and
partially coupled spin systems.
| [
{
"version": "v1",
"created": "Tue, 4 May 1999 10:40:16 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Jones",
"J. A.",
""
],
[
"Knill",
"E.",
""
]
] |
quant-ph/9905009 | Richard J. Hughes | Richard J. Hughes, William T. Buttler, Paul G. Kwiat, Steve K.
Lamoreaux, George L. Morgan, Jane E. Nordholt and C. G. Peterson | Practical quantum cryptography for secure free-space communications | 12 pages, 4 figures | null | 10.1117/12.346170 | LA-UR-99-737 | quant-ph | null | Quantum cryptography is an emerging technology in which two parties may
simultaneously generate shared, secret cryptographic key material using the
transmission of quantum states of light. The security of these transmissions is
based on the inviolability of the laws of quantum mechanics and
information-theoretically secure post-processing methods. An adversary can
neither successfully tap the quantum transmissions, nor evade detection, owing
to Heisenberg's uncertainty principle. In this paper we describe the theory of
quantum cryptography, and the most recent results from our experimental
free-space system with which we have demonstrated for the first time the
feasibility of quantum key generation over a point-to-point outdoor atmospheric
path in daylight. We achieved a transmission distance of 0.5 km, which was
limited only by the length of the test range. Our results provide strong
evidence that cryptographic key material could be generated on demand between a
ground station and a satellite (or between two satellites), allowing a
satellite to be securely re-keyed on orbit. We present a feasibility analysis
of surface-to-satellite quantum key generation.
| [
{
"version": "v1",
"created": "Tue, 4 May 1999 17:43:37 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Hughes",
"Richard J.",
""
],
[
"Buttler",
"William T.",
""
],
[
"Kwiat",
"Paul G.",
""
],
[
"Lamoreaux",
"Steve K.",
""
],
[
"Morgan",
"George L.",
""
],
[
"Nordholt",
"Jane E.",
""
],
[
"Peterson",
"C. G.",
""
]
] |
quant-ph/9905010 | Dr P. K. Panigrahi | V. Sunilkumar, B. A. Bambah, P. K. Panigrahi and V. Srinivasan | Coherent States for the Deformed Algebras | 11 pages, REVTeX | null | null | null | quant-ph hep-th math-ph math.MP | null | We provide a unified approach for finding the coherent states of various
deformed algebras, including quadratic, Higgs and q-deformed algebras, which
are relevant for many physical problems. For the non-compact cases, coherent
states, which are the eigenstates of the respective annihilation operators, are
constructed by finding the canonical conjugates of these operators. We give a
general procedure to map these deformed algebras to appropriate Lie algebras.
Generalized coherent states, in the Perelomov sense, follow from this
construction.
| [
{
"version": "v1",
"created": "Wed, 5 May 1999 04:22:56 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sunilkumar",
"V.",
""
],
[
"Bambah",
"B. A.",
""
],
[
"Panigrahi",
"P. K.",
""
],
[
"Srinivasan",
"V.",
""
]
] |
quant-ph/9905011 | Dr P. K. Panigrahi | N. Gurappa, Prasanta K. Panigrahi and T. Soloman Raju | Quantum equivalent of the Bertrand's theorem | 11 pages, REVTeX | Mod.Phys.Lett.A15:1851-1858,2000 | 10.1142/S0217732300002255 | null | quant-ph | null | A procedure for constructing bound state potentials is given. We show that,
under the natural conditions imposed on a radial eigenvalue problem, the only
special cases of the general central potential, which are exactly solvable and
have infinite number of energy eigenvalues, are the Coulomb and harmonic
oscillator potentials.
| [
{
"version": "v1",
"created": "Wed, 5 May 1999 05:12:32 GMT"
}
] | 2011-07-19T00:00:00 | [
[
"Gurappa",
"N.",
""
],
[
"Panigrahi",
"Prasanta K.",
""
],
[
"Raju",
"T. Soloman",
""
]
] |
quant-ph/9905012 | Habatwa Vincent Mweene | Habatwa Vincent Mweene (Physics Department, University of Zambia) | Derivation of Spin Vectors and Operators From First Principles | LaTeX, 30 pages, submitted to "Foundations of Physics." Replaced to
thoroughly revise notation and improve some sections | null | null | UNZAPHYS-001 | quant-ph | null | The interpretation of quantum mechanics due to Lande' is applied to the
connection between wave mechanics and matrix mechanics. The connection between
the differential eigenvalue equation and the matrix eigenvalue equation for an
operator is elucidated. In particular, we show that the elements of a matrix
vector state are probability amplitudes with a structure rather than being mere
constants. We obtain the most general expressions for the probability
amplitudes for the description of spin-1/2 measurements. As a result, we derive
spin-1/2 operators and vectors from first principles. The procedure used is
analogous to that by which orbital angular momentum wavefunctions and operators
are transformed to matrix mechanics vectors and matrices. The most generalized
forms of the spin operators and their eigenvectors for spin-1/2 are derived and
shown to reduce to the Pauli spin matrices and vectors in an appropriate limit.
| [
{
"version": "v1",
"created": "Wed, 5 May 1999 11:44:49 GMT"
},
{
"version": "v2",
"created": "Fri, 30 Jun 2000 23:29:58 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mweene",
"Habatwa Vincent",
"",
"Physics Department, University of Zambia"
]
] |
quant-ph/9905013 | Tommaso Calarco | T. Calarco (1,2), E.A. Hinds (3), D. Jaksch (1), J. Schmiedmayer (4),
J.I. Cirac (1), and P. Zoller (1) ((1) Institut fuer Theoretische Physik,
Universitaet Innsbruck, Innsbruck, Austria (2) ECT*, Villa Tambosi,
Villazzano (Trento), Italy (3) Sussex Centre for Optical and Atomic Physics,
Brighton, United Kingdom (4) Institut fuer Experimentalphysik, universitaet
Innsbruck, Innsbruck, Austria) | Quantum gates with neutral atoms: Controlling collisional interactions
in time dependent traps | 10 pages, 3 figures | Phys. Rev. A 61, 022304 (2000) | 10.1103/PhysRevA.61.022304 | null | quant-ph | null | We theoretically study specific schemes for performing a fundamental
two-qubit quantum gate via controlled atomic collisions by switching
microscopic potentials. In particular we calculate the fidelity of a gate
operation for a configuration where a potential barrier between two atoms is
instantaneously removed and restored after a certain time. Possible
implementations could be based on microtraps created by magnetic and electric
fields, or potentials induced by laser light.
| [
{
"version": "v1",
"created": "Wed, 5 May 1999 16:09:05 GMT"
},
{
"version": "v2",
"created": "Thu, 20 May 1999 10:48:11 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Calarco",
"T.",
""
],
[
"Hinds",
"E. A.",
""
],
[
"Jaksch",
"D.",
""
],
[
"Schmiedmayer",
"J.",
""
],
[
"Cirac",
"J. I.",
""
],
[
"Zoller",
"P.",
""
]
] |
quant-ph/9905014 | A. M. Lisewski | A.M. Lisewski | On the classical hydrodynamic limit of quantum field theories | minor changes, 9 pages, no figures, uses revtex | null | null | null | quant-ph | null | We discuss the transition from a quantum to a classical domain for a model
where a separation into environment and system is explicitely not given.
Utilizing the coarse graining procedure for free quantum fields we also apply
the projection method and the Hamiltonian principle to study possible cases of
emergent classicality. General conditions for classical dynamics are given.
Eventually, they lead to the equations of motion for a perfect classical fluid.
| [
{
"version": "v1",
"created": "Wed, 5 May 1999 20:14:47 GMT"
},
{
"version": "v2",
"created": "Wed, 30 Jun 1999 12:53:58 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Lisewski",
"A. M.",
""
]
] |
quant-ph/9905015 | 'Andrey V. Novikov-Borodin' | Andrey V. Novikov-Borodin (Institute for Nuclear Research of Russian
Academy of Sciences, Moscow, Russia) | Wave Function Interpretation and Quantum Mechanics Equations | 5 pages, LaTeX | null | null | null | quant-ph | null | The quantum mechanics description of a physical object stretched in space and
stable in time from the relativistic space-time properties point of view,
introduced in special theory of relativity, is considered and analysed. The
mathematical model of physical objects is proposed. This model gives a
possibility to unite a description of corpuscular and wave properties of real
physical objects, i.e. fields and particles. There are substantiated an
approach and a mathematical pattern which give a possibility to describe
physical object not only in causal, but also in absolute remote fields of the
Minkowski space. Applying the proposed approach to the microcosm description,
one can get the equations that in passage to the limit transfer to such quantum
mechanics equations as Schrodinger, Klein-Gordon-Fock and in particular case -
the wave equation. The event nature of the received equations is discussed. It
is shown that all mentioned equations reflect the space-time relativistic
properties during the description of the invariant and non-invariant physics
object characteristics.
| [
{
"version": "v1",
"created": "Wed, 5 May 1999 22:31:54 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Novikov-Borodin",
"Andrey V.",
"",
"Institute for Nuclear Research of Russian\n Academy of Sciences, Moscow, Russia"
]
] |
quant-ph/9905016 | Marcis Auzinsh | M. Auzinsh, R. Damburg (Dept. of Physics, University of Latvia) | A simple formula for ground state energy of a two-electron atom | LaTeX 5 pages, 1 figure, 1 table | Latv.J.Phys.Tech.Sci. 5 (1999) 22 | null | null | quant-ph physics.atom-ph physics.ed-ph | null | A simple expression for a ground state energy for a two-electron atom is
derived. For this, assumption based upon the Niels Bohr ''old'' quantum
mechanics idea about electron correlation in a two-electron atom is exploited.
Results are compared with experimental data and theoretical results based on a
variation approach.
| [
{
"version": "v1",
"created": "Thu, 6 May 1999 10:19:32 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Auzinsh",
"M.",
"",
"Dept. of Physics, University of Latvia"
],
[
"Damburg",
"R.",
"",
"Dept. of Physics, University of Latvia"
]
] |
quant-ph/9905017 | Paolo Facchi | P. Facchi and S. Pascazio | Temporal behavior and quantum Zeno time of an excited state of the
hydrogen atom | 11 pages | Phys.Lett. A241 (1998) 139-144 | 10.1016/S0375-9601(98)00144-3 | null | quant-ph | null | The quantum "Zeno" time of the 2P-1S transition of the hydrogen atom is
computed and found to be approximately 3.59 10^{-15}s (the lifetime is
approximately 1.595 10^{-9}s). The temporal behavior of this system is analyzed
in a purely quantum field theoretical framework and is compared to the
exponential decay law.
| [
{
"version": "v1",
"created": "Thu, 6 May 1999 15:10:32 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Facchi",
"P.",
""
],
[
"Pascazio",
"S.",
""
]
] |
quant-ph/9905018 | Nicolas Gisin | N. Gisin and B. Gisin | A local hidden variable model of quantum correlation exploiting the
detection loophole | 6 pages + 1 figure. A software producing data violating Bell
inequality between two classical computers can be downloaded from
http://www.gapoptique.unige.ch/News/BellSoft.asp | Phys.Lett. A260 (1999) 323-327 | 10.1016/S0375-9601(99)00519-8 | null | quant-ph | null | A local hidden variable model exploiting the detection loophole to reproduce
exactly the quantum correlation of the singlet state is presented. The model is
shown to be compatible with both the CHSH and the CH Bell inequalities.
Moreover, it bears the same rotational symmetry as spins. The reason why the
model can reproduce the quantum correlation without violating the Bell theorem
is that in the model the efficiency of the detectors depends on the local
hidden variable. On average the detector efficiency is limited to 75%.
| [
{
"version": "v1",
"created": "Thu, 6 May 1999 15:53:58 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Gisin",
"N.",
""
],
[
"Gisin",
"B.",
""
]
] |
quant-ph/9905019 | Theor. Phys. Group | Qiong-gui Lin | Quantum-mechanical model for particles carrying electric charge and
magnetic flux in two dimensions | 12 pages, REVTeX, no figure | Phys.Rev. A59 (1999) 3228-3235 | 10.1103/PhysRevA.59.3228 | null | quant-ph hep-th | null | We propose a simple quantum mechanical equation for $n$ particles in two
dimensions, each particle carrying electric charge and magnetic flux. Such
particles appear in (2+1)-dimensional Chern-Simons field theories as charged
vortex soliton solutions, where the ratio of charge to flux is a constant
independent of the specific solution. As an approximation, the charge-flux
interaction is described here by the Aharonov-Bohm potential, and the
charge-charge interaction by the Coulomb one. The equation for two particles,
one with charge and flux ($q, \Phi/Z$) and the other with ($-Zq, -\Phi$) where
$Z$ is a pure number is studied in detail. The bound state problem is solved
exactly for arbitrary $q$ and $\Phi$ when $Z>0$. The scattering problem is
exactly solved in parabolic coordinates in special cases when $q\Phi/2\pi\hbar
c$ takes integers or half integers. In both cases the cross sections obtained
are rather different from that for pure Coulomb scattering.
| [
{
"version": "v1",
"created": "Fri, 7 May 1999 10:20:21 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Lin",
"Qiong-gui",
""
]
] |
quant-ph/9905020 | Miloslav Znojil | Miloslav Znojil | PT -symmetric harmonic oscillators | 9 pages, submitted to Phys. Lett. A | Phys.Lett. A259 (1999) 220-223 | 10.1016/S0375-9601(99)00429-6 | null | quant-ph | null | Within the framework of the recently proposed formalism using non-hermitean
Hamiltonians constrained merely by their PT invariance we describe a new
exactly solvable family of the harmonic-oscillator-like potentials with
non-equidistant spectrum. Our one-dimensional superposition of the harmonic x^2
with the centrifugal-like G/x^2 is regularized by a purely imaginary shift of
$x$.
| [
{
"version": "v1",
"created": "Fri, 7 May 1999 12:48:33 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Znojil",
"Miloslav",
""
]
] |
quant-ph/9905021 | Dan Solomon | Dan Solomon | Gauge invariance and the vacuum state | 32 pages | Can.J.Phys. 76 (1998) 111-127 | 10.1139/cjp-76-2-111 | null | quant-ph | null | Quantum field theory is assumed to be gauge invariant. It is shown that for a
Dirac field the assumption of gauge invariance impacts on the way the vacuum
state is defined. It is shown that the conventional definition of the vacuum
state must be modified to take into account the requirements of gauge
invariance.
| [
{
"version": "v1",
"created": "Fri, 7 May 1999 14:13:14 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Solomon",
"Dan",
""
]
] |
quant-ph/9905022 | Fumiaki Morikoshi | Fumiaki Morikoshi | Entanglement measure and distance | 3 pages, REVTeX | null | null | EPHOU-99-006 | quant-ph | null | Recently a new entanglemenet dilution scheme has been constructed by Lo and
Popescu. This paper points out that this result has a deep implication that the
entanglement measure for bipartite pure states is independent of the distance
between entangled two systems.
| [
{
"version": "v1",
"created": "Fri, 7 May 1999 14:28:13 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Jul 1999 08:10:18 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Morikoshi",
"Fumiaki",
""
]
] |
quant-ph/9905023 | Inigo L. Egusquiza | I. L. Egusquiza and J. G. Muga | Free motion time-of-arrival operator and probability distribution | 10 a4 pages, no figures | Phys.Rev.A61:012104,1999 | 10.1103/PhysRevA.61.012104 | EHU-FT/9901 | quant-ph | null | We reappraise and clarify the contradictory statements found in the
literature concerning the time-of-arrival operator introduced by Aharonov and
Bohm in Phys. Rev. {\bf 122}, 1649 (1961). We use Naimark's dilation theorem to
reproduce the generalized decomposition of unity (or POVM) from any
self-adjoint extension of the operator, emphasizing a natural one, which arises
from the analogy with the momentum operator on the half-line. General time
operators are set within a unifying perspective. It is shown that they are not
in general related to the time of arrival, even though they may have the same
form.
| [
{
"version": "v1",
"created": "Fri, 7 May 1999 14:30:19 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Egusquiza",
"I. L.",
""
],
[
"Muga",
"J. G.",
""
]
] |
quant-ph/9905024 | Lucien Hardy | Lucien Hardy and David D. Song | No Signalling and Probabilistic Quantum Cloning | 5 pages | Phys.Lett. A259 (1999) 331-333 | 10.1016/S0375-9601(99)00448-X | null | quant-ph | null | We show that the condition of no faster-than-light signalling restricts the
number of quantum states that can be cloned in a given Hilbert space. This
condition leads to the constraints on a probabilistic quantum cloning machine
(PQCM) recently found by Duan and Guo.
| [
{
"version": "v1",
"created": "Fri, 7 May 1999 14:35:11 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Hardy",
"Lucien",
""
],
[
"Song",
"David D.",
""
]
] |
quant-ph/9905025 | Mikhail Lukin | M.D.Lukin and P.R.Hemmer | Coherent Control of Atom-Atom Interactions and Entanglement using
Optical Fields | null | null | null | null | quant-ph | null | Two-photon optical transitions combined with long-range dipole-dipole
interactions can be used for the coherent manipulation of collective metastable
states composed of different atoms. We show that it is possible to induce
optical resonances accompanied by the generation of entangled superpositions of
the atomic states. Resonances of this kind can be used to implement quantum
logic gates using optically excited single atoms (impurities) in the condensed
phase.
| [
{
"version": "v1",
"created": "Fri, 7 May 1999 14:54:38 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Lukin",
"M. D.",
""
],
[
"Hemmer",
"P. R.",
""
]
] |
quant-ph/9905026 | Rusins Freivalds | Andris Ambainis, Richard Bonner, Rusins Freivalds, Marats Golovkins,
Marek Karpinski | Quantum finite multitape automata | 14 pages, LaTeX | null | null | null | quant-ph cs.CC cs.FL | null | Quantum finite automata were introduced by C.Moore, J.P. Crutchfield, and by
A.Kondacs and J.Watrous. This notion is not a generalization of the
deterministic finite automata. Moreover, it was proved that not all regular
languages can be recognized by quantum finite automata. A.Ambainis and
R.Freivalds proved that for some languages quantum finite automata may be
exponentially more concise rather than both deterministic and probabilistic
finite automata. In this paper we introduce the notion of quantum finite
multitape automata and prove that there is a language recognized by a quantum
finite automaton but not by a deterministic or probabilistic finite automata.
This is the first result on a problem which can be solved by a quantum computer
but not by a deterministic or probabilistic computer. Additionally we discover
unexpected probabilistic automata recognizing complicated languages.
| [
{
"version": "v1",
"created": "Fri, 7 May 1999 15:05:45 GMT"
}
] | 2011-06-14T00:00:00 | [
[
"Ambainis",
"Andris",
""
],
[
"Bonner",
"Richard",
""
],
[
"Freivalds",
"Rusins",
""
],
[
"Golovkins",
"Marats",
""
],
[
"Karpinski",
"Marek",
""
]
] |
quant-ph/9905027 | Eric Dennis | Eric Dennis | Toward fault-tolerant quantum computation without concatenation | 12 pages, 2 figures, replaced: new stuff on error models, numerical
example for concatenation criteria | Phys.Rev.A63:052314,2001 | 10.1103/PhysRevA.63.052314 | null | quant-ph | null | It has been known that quantum error correction via concatenated codes can be
done with exponentially small failure rate if the error rate for physical
qubits is below a certain accuracy threshold. Other, unconcatenated codes with
their own attractive features-improved accuracy threshold, local
operations-have also been studied. By iteratively distilling a certain
two-qubit entangled state it is shown how to perform an encoded Toffoli gate,
important for universal computation, on CSS codes that are either
unconcatenated or, for a range of very large block sizes, singly concatenated.
| [
{
"version": "v1",
"created": "Fri, 7 May 1999 18:48:08 GMT"
},
{
"version": "v2",
"created": "Fri, 14 Jul 2000 02:51:10 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Dennis",
"Eric",
""
]
] |
quant-ph/9905028 | Richard J. Nelson | Richard J. Nelson, David G. Cory, and Seth Lloyd | Experimental Demonstration of Greenberger-Horne-Zeilinger Correlations
Using Nuclear Magnetic Resonance | Latex2.09, 8 pages, 1 eps figure | null | 10.1103/PhysRevA.61.022106 | null | quant-ph | null | The Greenberger-Horne-Zeilinger (GHZ) effect provides an example of quantum
correlations that cannot be explained by classical local hidden variables. This
paper reports on the experimental realization of GHZ correlations using nuclear
magnetic resonance (NMR). The NMR experiment differs from the originally
proposed GHZ experiment in several ways: it is performed on mixed states rather
than pure states; and instead of being widely separated, the spins on which it
is performed are all located in the same molecule. As a result, the NMR version
of the GHZ experiment cannot entirely rule out classical local hidden
variables. It nonetheless provides an unambiguous demonstration of the
"paradoxical" GHZ correlations, and shows that any classical hidden variables
must communicate by non-standard and previously undetected forces. The NMR
demonstration of GHZ correlations shows the power of NMR quantum information
processing techniques for demonstrating fundamental effects in quantum
mechanics.
| [
{
"version": "v1",
"created": "Fri, 7 May 1999 21:28:47 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Nelson",
"Richard J.",
""
],
[
"Cory",
"David G.",
""
],
[
"Lloyd",
"Seth",
""
]
] |
quant-ph/9905029 | Xiao-Guang Wang | Xiao-Guang Wang | Phase properties of hypergeometric states and negative hypergeometric
states | 7 pages, 4 figures | J.Opt.BQuant.Semiclass.Opt.2:29-32,2000 | 10.1088/1464-4266/2/1/305 | null | quant-ph | null | We show that the three quantum states (P$\acute{o}$lya states, the
generalized non-classical states related to Hahn polynomials and negative
hypergeometric states) introduced recently as intermediates states which
interpolate between the binomial states and negative binomial states are
essentially identical. By using the Hermitial-phase-operator formalism, the
phase properties of the hypergeometric states and negative hypergeometric
states are studied in detail. We find that the number of peaks of phase
probability distribution is one for the hypergeometric states and $M$ for the
negative hypergeometric states.
| [
{
"version": "v1",
"created": "Sat, 8 May 1999 05:33:16 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Wang",
"Xiao-Guang",
""
]
] |
quant-ph/9905030 | Brett D. Altschul | Martin S. Altschul and Brett D. Altschul | A Realizable, Non-Null Schroedinger's Cat Experiment | 17 pages, 9 figures, RevTeX | null | null | null | quant-ph | null | Working from the Schroedinger's Cat paradigm, a series of experiments are
constructed. The Bedford-Wang experiment is examined, and the ambiguity in its
meaning is addressed. We eliminate this ambiguity by abandoning the idea of the
triggering event, replacing the two-state system with a mirror that undergoes
wave packet spreading. This creates an experimentally testable version of a
modified Schroedinger's Cat experiment for which a null result is not the
obvious outcome.
| [
{
"version": "v1",
"created": "Mon, 10 May 1999 01:15:36 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Altschul",
"Martin S.",
""
],
[
"Altschul",
"Brett D.",
""
]
] |
quant-ph/9905031 | A. C. de la Torre | A. C. de la Torre (Univ. Nac. de Mar del Plata, Argentina) | A one-dimensional lattice model for a quantum mechanical free particle | 8 pages. Revtex | Eur. Phys. J. D8, 165-168, 2000. | 10.1007/s100530050022 | null | quant-ph | null | Two types of particles, A and B with their corresponding antiparticles, are
defined in a one dimensional cyclic lattice with an odd number of sites. In
each step of time evolution, each particle acts as a source for the
polarization field of the other type of particle with nonlocal action but with
an effect decreasing with the distance: A -->...\bar{B} B \bar{B} B \bar{B} ...
; B --> A \bar{A} A \bar{A} A ... . It is shown that the combined distribution
of these particles obeys the time evolution of a free particle as given by
quantum mechanics.
| [
{
"version": "v1",
"created": "Mon, 10 May 1999 12:12:09 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"de la Torre",
"A. C.",
"",
"Univ. Nac. de Mar del Plata, Argentina"
]
] |
quant-ph/9905032 | A. C. de la Torre | A. C. de la Torre and A. Daleo (Univ. Nac. Mar del Plata) | Quantum Mechanics as a Classical Field Theory | 14 pages. revtex | null | null | null | quant-ph | null | The formalism of quantum mechanics is presented in a way that its
interpretation as a classical field theory is emphasized. Two coupled real
fields are defined with given equations of motion. Densities and currents
associated to the fields are found with their corresponding conserved
quantities. The behavior of these quantities under a galilean transformation
suggest the association of the fields with a quantum mechanical free particle.
An external potential is introduced in the Lagrange formalism. The description
is equivalent to the conventional Schr\"odinger equation treatment of a
particle. We discuss the attempts to build an interpretation of quantum
mechanics based on this scheme. The fields become the primary onthology of the
theory and the particles appear as emergent properties of the fields. These
interpretations face serious problems for systems with many degrees of freedom.
| [
{
"version": "v1",
"created": "Mon, 10 May 1999 15:23:32 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"de la Torre",
"A. C.",
"",
"Univ. Nac. Mar del Plata"
],
[
"Daleo",
"A.",
"",
"Univ. Nac. Mar del Plata"
]
] |
quant-ph/9905033 | Brau Fabian | F. Brau (Univ. of Mons-Hainaut) | Minimal Length Uncertainty Relation and Hydrogen Atom | 7 pages, REVTeX | J.Phys.A32:7691-7696,1999 | 10.1088/0305-4470/32/44/308 | UMH-PNT-99-12 | quant-ph | null | We propose a new approach to calculate perturbatively the effects of a
particular deformed Heisenberg algebra on energy spectrum. We use this method
to calculate the harmonic oscillator spectrum and find that corrections are in
agreement with a previous calculation. Then, we apply this approach to obtain
the hydrogen atom spectrum and we find that splittings of degenerate energy
levels appear. Comparison with experimental data yields an interesting upper
bound for the deformation parameter of the Heisenberg algebra.
| [
{
"version": "v1",
"created": "Mon, 10 May 1999 15:29:16 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Brau",
"F.",
"",
"Univ. of Mons-Hainaut"
]
] |
quant-ph/9905034 | Matt Visser | Stefano Liberati (SISSA, Trieste), Matt Visser (Washington University,
St Louis), Francesco Belgiorno (Milano), Dennis Sciama (SISSA, ICTP, Trieste;
Oxford) | Sonoluminescence as a QED vacuum effect. II: Finite Volume Effects | 23 pages, LaTeX 209, ReV-TeX 3.2, five figures | Phys.Rev. D61 (2000) 085024 | 10.1103/PhysRevD.61.085024 | null | quant-ph cond-mat hep-th | null | In a companion paper [quant-ph/9904013] we have investigated several
variations of Schwinger's proposed mechanism for sonoluminescence. We
demonstrated that any realistic version of Schwinger's mechanism must depend on
extremely rapid (femtosecond) changes in refractive index, and discussed ways
in which this might be physically plausible. To keep that discussion tractable,
the technical computations in that paper were limited to the case of a
homogeneous dielectric medium. In this paper we investigate the additional
complications introduced by finite-volume effects. The basic physical scenario
remains the same, but we now deal with finite spherical bubbles, and so must
decompose the electromagnetic field into Spherical Harmonics and Bessel
functions. We demonstrate how to set up the formalism for calculating Bogolubov
coefficients in the sudden approximation, and show that we qualitatively retain
the results previously obtained using the homogeneous-dielectric (infinite
volume) approximation.
| [
{
"version": "v1",
"created": "Mon, 10 May 1999 17:02:34 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Liberati",
"Stefano",
"",
"SISSA, Trieste"
],
[
"Visser",
"Matt",
"",
"Washington University,\n St Louis"
],
[
"Belgiorno",
"Francesco",
"",
"Milano"
],
[
"Sciama",
"Dennis",
"",
"SISSA, ICTP, Trieste;\n Oxford"
]
] |
quant-ph/9905035 | Emerson Silva Guerra | J. C. Retamal and E. S. Guerra | A protocol to preserve quantum coherence in cavity QED | 4 pages | null | null | null | quant-ph | null | We consider the problem of quantum decoherence in cavity QED devices and
investigate the possibility to preserve a Schroedinger cat as a coherent
superposition along the time.
| [
{
"version": "v1",
"created": "Mon, 10 May 1999 19:52:33 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Retamal",
"J. C.",
""
],
[
"Guerra",
"E. S.",
""
]
] |
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