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| versions
list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/9910110 | Bo-Sture Skagerstam | Per K Rekdal and Bo-Sture K Skagerstam | On the Phases Structure of the Micromaser System | 4 pages, 4 figures | null | 10.1016/S0030-4018(00)00922-6 | null | quant-ph cond-mat.stat-mech | null | We investigate, in an exact manner, the phase structure of the micromaser
system in terms of the physical parameters at hand like the atom cavity transit
time, the atom-photon frequency detuning, the number of thermal photons and the
probability for a pump atom to be in its excited state. Phase diagrams are
mapped out for various values of the physical parameters. At sufficiently large
values of the detuning, we find a ``twinkling'' mode of the micromaser system.
A correlation length is used to study fluctuations close to the various phase
transitions.
| [
{
"version": "v1",
"created": "Tue, 26 Oct 1999 18:01:18 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Rekdal",
"Per K",
""
],
[
"Skagerstam",
"Bo-Sture K",
""
]
] |
quant-ph/9910111 | Paolo Facchi | P. Facchi and S. Pascazio | Van Hove's "\lambda^2 t" limit in nonrelativistic and relativistic
field-theoretical models | 18 pages, 4 figures | Chaos, Solitons & Fractals 12 (2001) 2777 | 10.1016/S0960-0779(01)00090-X | null | quant-ph | null | Van Hove's "\lambda^2 t" limiting procedure is analyzed in some interesting
quantum field theoretical cases, both in nonrelativistic and relativistic
models. We look at the deviations from a purely exponential behavior in a decay
process and discuss the subtle issues of state preparation and initial time.
| [
{
"version": "v1",
"created": "Tue, 26 Oct 1999 18:28:51 GMT"
}
] | 2010-01-31T00:00:00 | [
[
"Facchi",
"P.",
""
],
[
"Pascazio",
"S.",
""
]
] |
quant-ph/9910112 | Michael Fleischhauer | M. Fleischhauer | Mirrorless oscillation based on resonantly enhanced 4-wave mixing:
All-order analytic solutions | proceedings ICLPQO'99 (Shanghai 99), 10 pages, 4 figures | null | null | null | quant-ph | null | The phase transition to mirrorless oscillation in resonantly enhanced
four-wave mixing in double-$\Lambda$ systems are studied analytically for the
ideal case of infinite lifetimes of ground-state coherences. The stationary
susceptibilities are obtained in all orders of the generated fields and
analytic solutions of the coupled nonlinear differential equations for the
field amplitudes are derived and discussed.
| [
{
"version": "v1",
"created": "Wed, 27 Oct 1999 08:52:11 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Fleischhauer",
"M.",
""
]
] |
quant-ph/9910113 | Paul Slater | Paul B. Slater (University of California) | High-Temperature Expansions of Bures and Fisher Information Priors | Six pages, LaTeX. The title has been shortened (and then further
modified), at the suggestion of a colleague. Other minor changes | Phys. Rev. E, 61 (2000) 6087 | 10.1103/PhysRevE.61.6087 | null | quant-ph | null | For certain infinite and finite-dimensional thermal systems, we obtain ---
incorporating quantum-theoretic considerations into Bayesian thermostatistical
investigations of Lavenda --- high-temperature expansions of priors over
inverse temperature beta induced by volume elements ("quantum Jeffreys' priors)
of Bures metrics. Similarly to Lavenda's results based on volume elements
(Jeffreys' priors) of (classical) Fisher information metrics, we find that in
the limit beta -> 0, the quantum-theoretic priors either conform to Jeffreys'
rule for variables over [0,infinity], by being proportional to 1/beta, or to
the Bayes-Laplace principle of insufficient reason, by being constant. Whether
a system adheres to one rule or to the other appears to depend upon its number
of degrees of freedom.
| [
{
"version": "v1",
"created": "Wed, 27 Oct 1999 21:50:49 GMT"
},
{
"version": "v2",
"created": "Mon, 1 Nov 1999 23:41:40 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Slater",
"Paul B.",
"",
"University of California"
]
] |
quant-ph/9910114 | Miloslav Znojil | Miloslav Znojil | Perturbation method with triangular propagators and anharmonicities of
intermediate strength | 37 pages (Latex file, incl. 6 tables) plus 6 ps file figures, to be
submitted to J. Math. Chem | J. Math. Chem. 28 (2000) 139 - 167. | null | null | quant-ph | null | I propose a new version of the Rayleigh - Schr\"{o}dinger perturbation
method. It admits a lower triangular matrix in place of the usual diagonal
propagator. Illustrated on rational anharmonicities
polynomial}(x)/polynomial}(x), treated as perturbations of (quasi-)exact
anharmonic oscilators. In this sense the method works in an
intermediate-coupling regime and bridges the gap between the weak- and
strong-coupling expansions.
| [
{
"version": "v1",
"created": "Wed, 27 Oct 1999 17:34:59 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Znojil",
"Miloslav",
""
]
] |
quant-ph/9910115 | Juanjo Alvarez | J.J. Alvarez and C. Gomez | A Comment on Fisher Information and Quantum Algorithms | 5 pages, LaTex file, Shor's factoring algorithm discussion added (new
sections 5 and 6) | null | null | IFT-UAM/CSIC-99-43 | quant-ph | null | We show that Grover's algorithm defines a geodesic in quantum Hilbert space
with the Fubini-Study metric. From statistical point of view Grover's algorithm
is characterized by constant Fisher's function. Quantum algorithms changing
complexity class as Shor's factorization does not preserve constant Fisher's
information. An adiabatic quantum factorization algorithm in non polynomial
time is presented to exemplify the result.
| [
{
"version": "v1",
"created": "Wed, 27 Oct 1999 22:54:18 GMT"
},
{
"version": "v2",
"created": "Sun, 12 Dec 1999 13:33:28 GMT"
},
{
"version": "v3",
"created": "Wed, 16 Feb 2000 23:26:03 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Alvarez",
"J. J.",
""
],
[
"Gomez",
"C.",
""
]
] |
quant-ph/9910116 | Helmut Kroger | H. Jirari, H. Kr\"oger, X.Q. Luo, K.J.M. Moriarty and S.G. Rubin | Quantum Instantons and Quantum Chaos | Extended version with new figures. Text (LaTeX), 5 Figures (epsi
files) | Phys.Lett. A281 (2001) 1-8 | 10.1016/S0375-9601(01)00096-2 | null | quant-ph hep-th | null | Based on a closed form expression for the path integral of quantum transition
amplitudes, we suggest rigorous definitions of both, quantum instantons and
quantum chaos. As an example we compute the quantum instanton of the double
well potential.
| [
{
"version": "v1",
"created": "Wed, 27 Oct 1999 23:00:51 GMT"
},
{
"version": "v2",
"created": "Tue, 15 Aug 2000 21:32:18 GMT"
},
{
"version": "v3",
"created": "Mon, 5 Feb 2001 19:10:19 GMT"
}
] | 2016-08-15T00:00:00 | [
[
"Jirari",
"H.",
""
],
[
"Kröger",
"H.",
""
],
[
"Luo",
"X. Q.",
""
],
[
"Moriarty",
"K. J. M.",
""
],
[
"Rubin",
"S. G.",
""
]
] |
quant-ph/9910117 | Konrad Banaszek | Konrad Banaszek (Warsaw University) | Measuring Quantum State in Phase Space | PhD thesis, 92 pages + 1 colour plate, 14 figures | null | null | null | quant-ph | null | In this thesis we present a direct scheme for measuring quasidistribution
functions of light. This scheme, based on photon counting, is derived from a
simple relation linking the Wigner function with photon statistics. We develop
a full multimode theory of the scheme, and show that the principle of the
measurement can be straightforwardly generalized to the detection of the
multimode radiation. We also discuss practical aspects of the scheme, including
statistical error, non-unit detection efficiency, and imperfect interference
visibility. Next, we report experimental realization of the scheme, and present
measurements of the Wigner function for several quantum states of light.
Finally, we study the general problem of statistical uncertainty in
quantum-optical photodetection measurements.
| [
{
"version": "v1",
"created": "Thu, 28 Oct 1999 10:11:27 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Banaszek",
"Konrad",
"",
"Warsaw University"
]
] |
quant-ph/9910118 | Nistor Nicolaevici | Nistor Nicolaevici | Dynamical mass shift for a partially reflecting moving mirror | 11 pages, LaTex | null | null | null | quant-ph | null | We consider the vacuum fluctuations contribution to the mass of a mirror in
an exactly soluble partially reflecting moving mirror model. Partial
reflectivity is accounted for by a repulsive delta-type potential localized
along the mirror trajectory. The mirror's mass is explicitly found as an
integral functional of the mirror's past trajectory.
| [
{
"version": "v1",
"created": "Thu, 28 Oct 1999 23:26:31 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Nicolaevici",
"Nistor",
""
]
] |
quant-ph/9910119 | Mozyrsky | Dima Mozyrsky | Exactly Solvable Model of Quantum Spin Interacting with Spin Environment | null | null | null | null | quant-ph | null | An exactly solvable model of a quantum spin interacting with a spin
environment is considered. The interaction is chosen to be such that the state
of the environment is conserved. The reduced density matrix of the spin is
calculated for arbitrary coupling strength and arbitrary time. The stationary
state of the spin is obtained explicitely in the $t \to \infty$ limit.
| [
{
"version": "v1",
"created": "Fri, 29 Oct 1999 01:23:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mozyrsky",
"Dima",
""
]
] |
quant-ph/9910120 | Stefan Kuhr | B. Ueberholz, S. Kuhr, D. Frese, D. Meschede, and V. Gomer | Counting Cold Collisions | LaTeX 2e, 5 pages, 4 Postscript figures | J. Phys. B: At. Mol. Opt. Phys. 33, L135 (2000). | 10.1088/0953-4075/33/4/105 | null | quant-ph | null | We have experimentally explored a novel possibility to study exoergic cold
atomic collisions. Trapping of small countable atom numbers in a shallow
magneto-optical trap and monitoring of their temporal dynamics allows us to
directly observe isolated two-body atomic collisions and provides detailed
information on loss statistics. A substantial fraction of such cold collisional
events has been found to result in the loss of one atom only. We have also
observed for the first time a strong optical suppression of ground-state
hyperfine-changing collisions in the trap by its repump laser field.
| [
{
"version": "v1",
"created": "Fri, 29 Oct 1999 09:20:02 GMT"
},
{
"version": "v2",
"created": "Wed, 8 Dec 1999 10:31:10 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ueberholz",
"B.",
""
],
[
"Kuhr",
"S.",
""
],
[
"Frese",
"D.",
""
],
[
"Meschede",
"D.",
""
],
[
"Gomer",
"V.",
""
]
] |
quant-ph/9910121 | Gert-Ludwig Ingold | Gert-Ludwig Ingold, Rodolfo A. Jalabert, Klaus Richter | Semiclassical analysis of level widths for one-dimensional potentials | 8 pages, 2 figures, RevTeX | Am. J. Phys. 69, 201-206 (2001) | 10.1119/1.1288129 | null | quant-ph cond-mat physics.atom-ph | null | We present a semiclassical study of level widths for a class of
one-dimensional potentials in the presence of an ohmic environment. Employing
an expression for the dipole matrix element in terms of the Fourier transform
of the classical path we obtain the level widths within the Golden rule
approximation. It is found that for potentials with an asymptotic power-law
behavior, which may in addition be limited by an infinite wall, the width that
an eigenstate of the isolated system acquires due to the coupling to the
environment is proportional to its quantum number.
| [
{
"version": "v1",
"created": "Fri, 29 Oct 1999 13:43:39 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ingold",
"Gert-Ludwig",
""
],
[
"Jalabert",
"Rodolfo A.",
""
],
[
"Richter",
"Klaus",
""
]
] |
quant-ph/9910122 | John Smolin | Pawel Horodecki, John A. Smolin, Barbara M. Terhal and Ashish V.
Thapliyal | Rank Two Bipartite Bound Entangled States Do Not Exist | 5 pages LaTeX, many corrections and updated references | null | null | null | quant-ph | null | We explore the relation between the rank of a bipartite density matrix and
the existence of bound entanglement. We show a relation between the rank,
marginal ranks, and distillability of a mixed state and use this to prove that
any rank n bound entangled state must have support on no more than an n \times
n Hilbert space. A direct consequence of this result is that there are no
bipartite bound entangled states of rank two. We also show that a separability
condition in terms of a quantum entropy inequality is associated with the above
results. We explore the idea of how many pure states are needed in a mixture to
cancel the distillable entanglement of a Schmidt rank n pure state and provide
a lower bound of n-1. We also prove that a mixture of a non-zero amount of any
pure entangled state with a pure product state is distillable.
| [
{
"version": "v1",
"created": "Fri, 29 Oct 1999 16:30:43 GMT"
},
{
"version": "v2",
"created": "Fri, 4 Feb 2000 15:57:54 GMT"
},
{
"version": "v3",
"created": "Wed, 6 Jun 2001 21:00:03 GMT"
},
{
"version": "v4",
"created": "Thu, 16 Aug 2001 20:30:29 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Horodecki",
"Pawel",
""
],
[
"Smolin",
"John A.",
""
],
[
"Terhal",
"Barbara M.",
""
],
[
"Thapliyal",
"Ashish V.",
""
]
] |
quant-ph/9910123 | Asher Peres | Asher Peres | Opposite momenta lead to opposite directions | 3 pages LaTeX, submitted to American Journal of Physics | Am. J. Phys. 68 (2000) 991 | 10.1119/1.1285946 | null | quant-ph | null | When a particle decays into two fragments, the wavefunctions of the latter
are spherical shells with expanding radii. In spite of this spherical symmetry,
the two particles can be detected only in opposite directions.
| [
{
"version": "v1",
"created": "Mon, 1 Nov 1999 12:35:33 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Peres",
"Asher",
""
]
] |
quant-ph/9910124 | Michael Keyl | M. Keyl, R. F. Werner | The Rate of Optimal Purification procedures | LaTeX2e, 24 pages, 4 figures | null | null | null | quant-ph | null | Purification is a process in which decoherence is partially reversed by using
several input systems which have been subject to the same noise. The purity of
the outputs generally increases with the number of input systems, and decreases
with the number of required output systems. We construct the optimal quantum
operations for this task, and discuss their asymptotic behaviour as the number
of inputs goes to infinity. The rate at which output systems may be generated
depends crucially on the type of purity requirement. If one tests the purity of
the outputs systems one at a time, the rate is infinite: this fidelity may be
made to approach 1, while at the same time the number of outputs goes to
infinity arbitrarily fast. On the other hand, if one also requires the
correlations between outputs to decrease, the rate is zero: if fidelity with
the pure product state is to go to 1, the number of outputs per input goes to
zero. However, if only a fidelity close to 1 is required, the optimal purifier
achieves a positive rate, which we compute.
| [
{
"version": "v1",
"created": "Mon, 1 Nov 1999 18:37:36 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Keyl",
"M.",
""
],
[
"Werner",
"R. F.",
""
]
] |
quant-ph/9910125 | Haret Rosu | D. J. Fernandez C., H. C. Rosu | Quantum mechanical spectral engineering by scaling intertwining | 8 twocolumn pages, 5 figures | Physica Scripta 64 (2001) 177-183 | 10.1238/Physica.Regular.064a00177 | null | quant-ph | null | Using the concept of spectral engineering we explore the possibilities of
building potentials with prescribed spectra offered by a modified intertwining
technique involving operators which are the product of a standard first-order
intertwiner and a unitary scaling. In the same context we study the iterations
of such transformations finding that the scaling intertwining provides a
different and richer mechanism in designing quantum spectra with respect to
that given by the standard intertwining
| [
{
"version": "v1",
"created": "Mon, 1 Nov 1999 23:09:32 GMT"
},
{
"version": "v2",
"created": "Wed, 22 Aug 2001 22:09:25 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"C.",
"D. J. Fernandez",
""
],
[
"Rosu",
"H. C.",
""
]
] |
quant-ph/9911001 | wai bong Yeung | Wai Bong Yeung | The Schrodinger Equation From a Quadratic Hamiltonian System | 3 pages | null | null | null | quant-ph | null | We regard the real and imaginary parts of the Schrodinger wave function as
canonical conjugate variables.With this pair of conjugate variables and some
other 2n pairs, we construct a quadratic Hamiltonian density. We then show that
the Schrodinger Equation follows from the Hamilton's Equation of motion when
the Planck frequency is much larger than the characteristic frequencies of the
Hamiltonian system. The Hamiltonian and the normal mode solutions coincide,
respectively, with the energy expectation value and the energy eigenstates of
the corresponding quantum mechanical system.
| [
{
"version": "v1",
"created": "Tue, 2 Nov 1999 02:47:40 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Yeung",
"Wai Bong",
""
]
] |
quant-ph/9911002 | Hiroto Kubotani | Hiroto Kubotani (Kanagawa University) | Quantum Trajectory in Multi-Dimensional Non-Linear System | 12 pages, Latex, 12 figure; Changed to REVTeX sytle, Refined
numerical results | null | null | null | quant-ph gr-qc | null | We discuss quantum dynamics in multi-dimensional non-linear systems. It is
well-known that wave functions are localized in a kicked rotor model. However,
coupling with other degrees of freedom breaks the localization. In order to
clarify the difference, we describe the quantum dynamics by deterministic rigid
trajectories, which are accompanied with the de Broglie-Bohm interpretation of
quantum mechanics, instead of wave functions. A bundle of quantum trajectories
are repulsive through quantum potential and flow never to go across each other.
We show that, according to the degrees of freedom, this same property appears
differently.
| [
{
"version": "v1",
"created": "Tue, 2 Nov 1999 08:15:48 GMT"
},
{
"version": "v2",
"created": "Tue, 16 Jan 2001 07:25:38 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kubotani",
"Hiroto",
"",
"Kanagawa University"
]
] |
quant-ph/9911003 | Ali Mostafazadeh | Ali Mostafazadeh | A New Class of Adiabatic Cyclic States and Geometric Phases for
Non-Hermitian Hamiltonians | Plain Latex, accepted for publication in Phys. Lett. A | Phys. Lett. A 264 (1999) 11-17 | 10.1016/S0375-9601(99)00790-2 | null | quant-ph | null | For a T-periodic non-Hermitian Hamiltonian H(t), we construct a class of
adiabatic cyclic states of period T which are not eigenstates of the initial
Hamiltonian H(0). We show that the corresponding adiabatic geometric phase
angles are real and discuss their relationship with the conventional complex
adiabatic geometric phase angles. We present a detailed calculation of the new
adiabatic cyclic states and their geometric phases for a non-Hermitian analog
of the spin 1/2 particle in a precessing magnetic field.
| [
{
"version": "v1",
"created": "Wed, 3 Nov 1999 12:42:41 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Mostafazadeh",
"Ali",
""
]
] |
quant-ph/9911004 | Gui Lu Long | Gui Lu Long, Chang Cun Tu, Yan Song Li, Wei Lin Zhang and Hai Yang Yan | A novel SO(3) picture for quantum searching | 6 pages, 2 eps figures | null | null | null | quant-ph | null | An SO(3) picture of the generalized Grover's quantum searching algorithm,with
arbitrary unitary transformation and with arbitrary phase rotations, is
constructed. In this picture, any quantum search operation is a rotation in a 3
dimensional space. Exact formulas for the rotation angle and rotational axis
are given. The probability of finding the marked state is just $(z+1)/2$, where
z is the z-component of the state vector. Exact formulas for this probability
is easily obtained. The phase matching requirement and the failure of algorithm
when phase mismatches are clearly explained.
| [
{
"version": "v1",
"created": "Wed, 3 Nov 1999 13:15:38 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Long",
"Gui Lu",
""
],
[
"Tu",
"Chang Cun",
""
],
[
"Li",
"Yan Song",
""
],
[
"Zhang",
"Wei Lin",
""
],
[
"Yan",
"Hai Yang",
""
]
] |
quant-ph/9911005 | Hector Moya-Cessa | H. Moya-Cessa and P. Tombesi | Filtering Number States of the Vibrational Motion of an Ion | 7 pages, in press in Phys. Rev. A | Physical Review A 61, 025401 (2000) | 10.1103/PhysRevA.61.025401 | null | quant-ph | null | We propose a scheme to generate number states (and specific superpositions of
them) of the vibrational motion of a trapped ion. In particular, we show that
robust to noise qubits can be generated with arbitrary amplitudes.
| [
{
"version": "v1",
"created": "Wed, 3 Nov 1999 13:20:55 GMT"
}
] | 2013-03-13T00:00:00 | [
[
"Moya-Cessa",
"H.",
""
],
[
"Tombesi",
"P.",
""
]
] |
quant-ph/9911006 | Irena Dobrovolska | I.V. Dobrovolska and R.S. Tutik | A new approach to perturbation theory for a Dirac particle in a central
field | 12 pages, LaTeX | Physics Letters A 260 (1999) 10-16 | 10.1016/S0375-9601(99)00459-4 | null | quant-ph | null | The explicit semiclassical treatment of logarithmic perturbation theory for
the bound-state problem within the framework of the Dirac equation is
developed. Avoiding disadvantages of the standard approach in the description
of exited states, new handy recursion formulae with the same simple form both
for ground and exited states have been obtained. As an example, the
perturbation expansions for the energy eigenvalues for the Yukawa potential
containing the vector part as well as the scalar component are considered.
| [
{
"version": "v1",
"created": "Wed, 3 Nov 1999 16:26:20 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Dobrovolska",
"I. V.",
""
],
[
"Tutik",
"R. S.",
""
]
] |
quant-ph/9911007 | Cezary Sliwa | Iwo Bialynicki-Birula, Zofia Bialynicka-Birula, Cezary Sliwa | Motion of vortex lines in quantum mechanics | 10 pages, 5 figures | Phys. Rev. A 61, 032110 (2000) | 10.1103/PhysRevA.61.032110 | null | quant-ph | null | Exact analytic solutions of the time dependent Schrodinger equation are
produced that exhibit a variety of vortex structures. The qualitative analysis
of the motion of vortex lines is presented and various types of vortex behavior
are identified. Vortex creation and annihilation and vortex interactions are
illustrated in the special cases of the free motion, the motion in the harmonic
potential, and in the constant magnetic field. Similar analysis of the vortex
motions is carried out also for a relativistic wave equation.
| [
{
"version": "v1",
"created": "Wed, 3 Nov 1999 16:44:51 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Bialynicki-Birula",
"Iwo",
""
],
[
"Bialynicka-Birula",
"Zofia",
""
],
[
"Sliwa",
"Cezary",
""
]
] |
quant-ph/9911008 | Antonio Acin | A. Acin, R. Tarrach, G. Vidal | Optimal estimation of two-qubit pure-state entanglement | REVTEX, 9 pages, 1 figure | Phys. Rev. A 61, 62307 (2000) | 10.1103/PhysRevA.61.062307 | null | quant-ph | null | We present optimal measuring strategies for the estimation of the
entanglement of unknown two-qubit pure states and of the degree of mixing of
unknown single-qubit mixed states, of which N identical copies are available.
The most general measuring strategies are considered in both situations, to
conclude in the first case that a local, although collective, measurement
suffices to estimate entanglement, a non-local property, optimally.
| [
{
"version": "v1",
"created": "Wed, 3 Nov 1999 18:39:26 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Acin",
"A.",
""
],
[
"Tarrach",
"R.",
""
],
[
"Vidal",
"G.",
""
]
] |
quant-ph/9911009 | Richard Jozsa | Richard Jozsa and Juergen Schlienz | Distinguishability of States and von Neumann Entropy | 18 pages, Latex, 2 figures | null | 10.1103/PhysRevA.62.012301 | null | quant-ph | null | Consider an ensemble of pure quantum states |\psi_j>, j=1,...,n taken with
prior probabilities p_j respectively. We show that it is possible to increase
all of the pairwise overlaps |<\psi_i|\psi_j>| i.e. make each constituent pair
of the states more parallel (while keeping the prior probabilities the same),
in such a way that the von Neumann entropy S is increased, and dually, make all
pairs more orthogonal while decreasing S. We show that this phenomenon cannot
occur for ensembles in two dimensions but that it is a feature of almost all
ensembles of three states in three dimensions. It is known that the von Neumann
entropy characterises the classical and quantum information capacities of the
ensemble and we argue that information capacity in turn, is a manifestation of
the distinguishability of the signal states. Hence our result shows that the
notion of distinguishability within an ensemble is a global property that
cannot be reduced to considering distinguishability of each constituent pair of
states.
| [
{
"version": "v1",
"created": "Wed, 3 Nov 1999 20:34:01 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Jozsa",
"Richard",
""
],
[
"Schlienz",
"Juergen",
""
]
] |
quant-ph/9911010 | Haret Rosu | L.M. Nieto, H.C. Rosu, M. Santander | Hydrogen atom as an eigenvalue problem in 3D spaces of constant
curvature and minimal length | 6 pages, v3 | Mod. Phys. Lett. A 14 (1999) 2463-2469 | 10.1142/S021773239900256X | null | quant-ph | null | An old result of A.F. Stevenson [Phys. Rev.} 59, 842 (1941)] concerning the
Kepler-Coulomb quantum problem on the three-dimensional (3D) hypersphere is
considered from the perspective of the radial Schr\"odinger equations on 3D
spaces of any (either positive, zero or negative) constant curvature. Further
to Stevenson, we show in detail how to get the hypergeometric wavefunction for
the hydrogen atom case. Finally, we make a comparison between the ``space
curvature" effects and minimal length effects for the hydrogen spectrum
| [
{
"version": "v1",
"created": "Wed, 3 Nov 1999 22:18:48 GMT"
},
{
"version": "v2",
"created": "Thu, 11 Nov 1999 22:41:08 GMT"
},
{
"version": "v3",
"created": "Tue, 7 Dec 1999 16:00:56 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Nieto",
"L. M.",
""
],
[
"Rosu",
"H. C.",
""
],
[
"Santander",
"M.",
""
]
] |
quant-ph/9911011 | Ryutaroh Matsumoto | Ryutaroh Matsumoto and Tomohiko Uyematsu | Constructing quantum error-correcting codes for p^m-state systems from
classical error-correcting codes | 10 pages, LaTeX2e. To appear in IEICE Transactions on Fundamentals of
Electronics, Communications and Computer Sciences (ISSN 0916-8508), vol.
E83-A, no. 10, Oct. 2000. Revision on Dec. 14, 1999: Added a note on a
systematic construction of quantum codes with efficient decoding algorithms.
Revision on June 26, 2000: Corrected lots of errors, and added a review on
the overall error correction process. No original materials were added | IEICE Trans. Fundamentals, vol. E83-A, no. 10, pp. 1878-1883, Oct.
2000. Available from http://search.ieice.org/ | null | null | quant-ph | null | We generalize the construction of quantum error-correcting codes from
GF(4)-linear codes by Calderbank et al. to p^m-state systems. Then we show how
to determine the error from a syndrome. Finally we discuss a systematic
construction of quantum codes with efficient decoding algorithms.
| [
{
"version": "v1",
"created": "Thu, 4 Nov 1999 13:04:20 GMT"
},
{
"version": "v2",
"created": "Tue, 14 Dec 1999 09:01:52 GMT"
},
{
"version": "v3",
"created": "Mon, 26 Jun 2000 08:19:14 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Matsumoto",
"Ryutaroh",
""
],
[
"Uyematsu",
"Tomohiko",
""
]
] |
quant-ph/9911012 | Rajkumar Roychoudhury | Anjana Sinha and Rajkumar Roychoudhury | SWKB Quantization Rules for Bound States in Quantum Wells | 8 pages | null | 10.1088/0953-4075/33/7/401 | null | quant-ph | null | In a recent paper by Gomes and Adhikari (J.Phys B30 5987(1997)) a matrix
formulation of the Bohr-Sommerfield quantization rule has been applied to the
study of bound states in one dimension quantum wells. Here we study these
potentials in the frame work of supersymmetric WKB (SWKB) quantization
approximation and find that SWKB quantization rule is superior to the modified
Bohr-Sommerfield or WKB rules as it exactly reproduces the eigenenergies.
| [
{
"version": "v1",
"created": "Thu, 4 Nov 1999 08:17:00 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Sinha",
"Anjana",
""
],
[
"Roychoudhury",
"Rajkumar",
""
]
] |
quant-ph/9911013 | Dipankar Home | Somshubhro Bandyopadhyay | Qubit and Entanglement assisted Optimal Entanglement Concentration | Latex, 12 pages: Enlarged version: To appear in Phys. Rev. A. Changes
made: another protocol added, practical implementation of the proposals
discussed | Phys. Rev. A 62, 032308 (2000) | 10.1103/PhysRevA.62.032308 | null | quant-ph | null | We present two method for optimal entanglement concentration from pure
entangled states by local actions only. However a prior knowledge of the
Schmidt coefficients is required. The first method is optimally efficient only
when a finite ensemble of pure entangled states are available whereas the
second method realizes the single pair optimal concentration probability. We
also propose an entanglement assisted method which is again optimally efficient
even for a single pair. We also discuss concentrating entanglement from
N-partite cat like states.
| [
{
"version": "v1",
"created": "Thu, 4 Nov 1999 14:20:28 GMT"
},
{
"version": "v2",
"created": "Fri, 5 Nov 1999 03:39:35 GMT"
},
{
"version": "v3",
"created": "Tue, 23 Nov 1999 12:22:38 GMT"
},
{
"version": "v4",
"created": "Thu, 27 Apr 2000 13:41:59 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Bandyopadhyay",
"Somshubhro",
""
]
] |
quant-ph/9911014 | Yoon-Ho Kim | Yoon-Ho Kim, Maria V. Chekhova, Sergei P. Kulik, Yanhua Shih, and
Morton H. Rubin | First-order interference of nonclassical light emitted spontaneously at
different times | 5 pages, two-column, submitted to PRA | Phys. Rev. A 61, 051803(R) | 10.1103/PhysRevA.61.051803 | null | quant-ph | null | We study first-order interference in spontaneous parametric down-conversion
generated by two pump pulses that do not overlap in time. The observed
modulation in the angular distribution of the signal detector counting rate can
only be explained in terms of a quantum mechanical description based on
biphoton states. The condition for observing interference in the signal channel
is shown to depend on the parameters of the idler radiation.
| [
{
"version": "v1",
"created": "Thu, 4 Nov 1999 15:08:15 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Kim",
"Yoon-Ho",
""
],
[
"Chekhova",
"Maria V.",
""
],
[
"Kulik",
"Sergei P.",
""
],
[
"Shih",
"Yanhua",
""
],
[
"Rubin",
"Morton H.",
""
]
] |
quant-ph/9911015 | Sergio de Filippo | Sergio De Filippo | NMR spectroscopy and computing beyond myth and fiction | I am ashamed to have written this paper | null | null | null | quant-ph nucl-th | null | Only craziness I am ashamed about.
| [
{
"version": "v1",
"created": "Thu, 4 Nov 1999 18:08:57 GMT"
},
{
"version": "v2",
"created": "Mon, 26 Sep 2011 16:37:15 GMT"
}
] | 2011-09-27T00:00:00 | [
[
"De Filippo",
"Sergio",
""
]
] |
quant-ph/9911016 | Marcin Michalski | Marcin Michalski | Faster Than Light Communication | This paper has been withdrawn by the author, due a crucial error in
the main idea | null | null | null | quant-ph | null | This paper has been withdrawn by the author, due a crucial error in the main
idea.
| [
{
"version": "v1",
"created": "Thu, 4 Nov 1999 23:45:12 GMT"
},
{
"version": "v2",
"created": "Thu, 11 Nov 1999 18:35:20 GMT"
},
{
"version": "v3",
"created": "Tue, 16 Nov 1999 14:22:53 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Michalski",
"Marcin",
""
]
] |
quant-ph/9911017 | Robert J. C. Spreeuw | R.J.C. Spreeuw, D. Voigt, B.T. Wolschrijn and H.B. van Linden van den
Heuvell | Creating a low-dimensional quantum gas using dark states in an inelastic
evanescent-wave mirror | 8 pages, 4 figures | Phys. Rev. A 61, 053604 (2000) | 10.1103/PhysRevA.61.053604 | null | quant-ph | null | We discuss an experimental scheme to create a low-dimensional gas of
ultracold atoms, based on inelastic bouncing on an evanescent-wave mirror.
Close to the turning point of the mirror, the atoms are transferred into an
optical dipole trap. This scheme can compress the phase-space density and can
ultimately yield an optically-driven atom laser. An important issue is the
suppression of photon scattering due to ``cross-talk'' between the mirror
potential and the trapping potential. We propose that for alkali atoms the
photon scattering rate can be suppressed by several orders of magnitude if the
atoms are decoupled from the evanescent-wave light. We discuss how such dark
states can be achieved by making use of circularly-polarized evanescent waves.
| [
{
"version": "v1",
"created": "Fri, 5 Nov 1999 11:00:00 GMT"
},
{
"version": "v2",
"created": "Thu, 23 Dec 1999 14:33:29 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Spreeuw",
"R. J. C.",
""
],
[
"Voigt",
"D.",
""
],
[
"Wolschrijn",
"B. T.",
""
],
[
"Heuvell",
"H. B. van Linden van den",
""
]
] |
quant-ph/9911018 | Jaroslav Rehacek | J. Rehacek, J. Perina, P. Facchi, S. Pascazio, and L. Mista | Quantum Zeno effect in a probed downconversion process | 11 pages, 4 figures | Phys. Rev. A 62, 013804 (2000) | 10.1103/PhysRevA.62.013804 | null | quant-ph | null | The distorsion of a spontaneous downconvertion process caused by an auxiliary
mode coupled to the idler wave is analyzed. In general, a strong coupling with
the auxiliary mode tends to hinder the downconversion in the nonlinear medium.
On the other hand, provided that the evolution is disturbed by the presence of
a phase mismatch, the coupling may increase the speed of downconversion. These
effects are interpreted as being manifestations of quantum Zeno or anti-Zeno
effects, respectively, and they are understood by using the dressed modes
picture of the device. The possibility of using the coupling as a nontrivial
phase--matching technique is pointed out.
| [
{
"version": "v1",
"created": "Fri, 5 Nov 1999 13:14:04 GMT"
},
{
"version": "v2",
"created": "Sun, 30 Jan 2000 14:08:49 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Rehacek",
"J.",
""
],
[
"Perina",
"J.",
""
],
[
"Facchi",
"P.",
""
],
[
"Pascazio",
"S.",
""
],
[
"Mista",
"L.",
""
]
] |
quant-ph/9911019 | Fumiaki Morikoshi | Fumiaki Morikoshi | Recovery of entanglement lost in entanglement manipulation | 4 pages, 2 figures, REVTeX; minor corrections | Phys. Rev. Lett. 84, 3189 (2000) | 10.1103/PhysRevLett.84.3189 | EPHOU-99-013 | quant-ph | null | When an entangled state is transformed into another one with probability one
by local operations and classical communication, the quantity of entanglement
decreases. This letter shows that entanglement lost in the manipulation can be
partially recovered by an auxiliary entangled pair. As an application, a
maximally entangled pair can be obtained from two partially entangled pairs
with probability one. Finally, this recovery scheme reveals a fundamental
property of entanglement relevant to the existence of incomparable states.
| [
{
"version": "v1",
"created": "Fri, 5 Nov 1999 16:49:04 GMT"
},
{
"version": "v2",
"created": "Mon, 27 Mar 2000 06:59:53 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Morikoshi",
"Fumiaki",
""
]
] |
quant-ph/9911020 | Chris Isham | J. Hamilton, C.J. Isham and J. Butterfield | A Topos Perspective on the Kochen-Specker Theorem: III. Von Neumann
Algebras as the Base Category | Latex2e | null | null | Imperial/TP/99-0/5 | quant-ph | null | We extend the topos-theoretic treatment given in previous papers of assigning
values to quantities in quantum theory, and of related issues such as the
Kochen-Specker theorem. This extension has two main parts: the use of von
Neumann algebras as a base category (Section 2); and the relation of our
generalized valuations to (i) the assignment to quantities of intervals of real
numbers, and (ii) the idea of a subobject of the coarse-graining presheaf
(Section 3).
| [
{
"version": "v1",
"created": "Fri, 5 Nov 1999 18:06:33 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Hamilton",
"J.",
""
],
[
"Isham",
"C. J.",
""
],
[
"Butterfield",
"J.",
""
]
] |
quant-ph/9911021 | David Marcus Appleby | D.M. Appleby | Optimal Measurements of Spin Direction | 16 pages, AMS-latex. A few typographical errors corrected | Int. J. Theor. Phys. 39, 2231 (2000) | null | QMW-PH-99-18 | quant-ph | null | The accuracy of a measurement of the spin direction of a spin-s particle is
characterised, for arbitrary half-integral s. The disturbance caused by the
measurement is also characterised. The approach is based on that taken in
several previous papers concerning joint measurements of position and momentum.
As in those papers, a distinction is made between the errors of retrodiction
and prediction. Retrodictive and predictive error relationships are derived.
The POVM describing the outcome of a maximally accurate measurement process is
investigated. It is shown that, if the measurement is retrodictively optimal,
then the distribution of measured values is given by the initial state SU(2)
Q-function. If the measurement is predictively optimal, then the distribution
of measured values is related to the final state SU(2) P-function. The general
form of the unitary evolution operator producing an optimal measurement is
characterised.
| [
{
"version": "v1",
"created": "Fri, 5 Nov 1999 23:01:49 GMT"
},
{
"version": "v2",
"created": "Sun, 23 Jan 2000 21:07:45 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Appleby",
"D. M.",
""
]
] |
quant-ph/9911022 | Adan Cabello | Adan Cabello | Kochen-Specker theorem and experimental test on hidden variables | 4 pages, 1 figure. To appear in Int. J. Mod. Phys. A | Int. J. Mod. Phys. A 15 (2000) 2813 | 10.1142/S0217751X00002020 | null | quant-ph | null | A recent proposal to experimentally test quantum mechanics against
noncontextual hidden-variable theories [Phys. Rev. Lett. 80, 1797 (1998)] is
shown to be related with the smallest proof of the Kochen-Specker theorem
currently known [Phys. Lett. A 212, 183 (1996)]. This proof contains eighteen
yes-no questions about a four-dimensional physical system, combined in nine
mutually incompatible tests. When these tests are considered as tests about a
two-part two-state system, then quantum mechanics and non-contextual hidden
variables make the same predictions for eight of them, but make different
predictions for the ninth. Therefore, this ninth test would allow us to
discriminate between quantum mechanics and noncontextual hidden-variable
theories in a (gedanken) single run experiment.
| [
{
"version": "v1",
"created": "Sat, 6 Nov 1999 15:58:09 GMT"
}
] | 2016-12-21T00:00:00 | [
[
"Cabello",
"Adan",
""
]
] |
quant-ph/9911023 | Adan Cabello | Adan Cabello | Nonlocality without inequalities has not been proved for maximally
entangled states | 7 pages, 2 figures. To appear in Phys. Rev. A | Phys. Rev. A 61 (2000) 022119 | 10.1103/PhysRevA.61.022119 | null | quant-ph | null | Two approaches to extend Hardy's proof of nonlocality without inequalities to
maximally entangled states of bipartite two-level systems are shown to fail. On
one hand, it is shown that Wu and co-workers' proof [Phys. Rev. A 53, R1927
(1996)] uses an effective state which is not maximally entangled. On the other
hand, it is demonstrated that Hardy's proof cannot be generalized by the
replacement of one of the four von Neumann measurements involved in the
original proof by a generalized measurement to unambiguously discriminate
between non-orthogonal states.
| [
{
"version": "v1",
"created": "Sat, 6 Nov 1999 16:02:08 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Cabello",
"Adan",
""
]
] |
quant-ph/9911024 | Adan Cabello | Adan Cabello | Comment on "Non-contextual hidden variables and physical measurements" | 2 pages | null | null | null | quant-ph | null | Kent's conclusion that ``non-contextual hidden variable theories cannot be
excluded by theoretical arguments of the Kochen-Specker type once the
imprecision in real world experiments is taken into account'' [Phys. Rev. Lett.
83, 3755 (1999)], is criticized. The Kochen-Specker theorem just points out
that it is impossible even conceive a hidden variable model in which the
outcomes of all measurements are pre-determined; it does not matter if these
measurements are performed or not, or even if these measurements can be
achieved only with finite precision.
| [
{
"version": "v1",
"created": "Sat, 6 Nov 1999 16:04:30 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Cabello",
"Adan",
""
]
] |
quant-ph/9911025 | Adan Cabello | Adan Cabello | Quantum key distribution without alternative measurements | REVTeX, 5 pages, 2 figures. Published version with some comments | Phys. Rev. A 61 (2000) 052312 | 10.1103/PhysRevA.61.052312 | null | quant-ph | null | Entanglement swapping between Einstein-Podolsky-Rosen (EPR) pairs can be used
to generate the same sequence of random bits in two remote places. A quantum
key distribution protocol based on this idea is described. The scheme exhibits
the following features. (a) It does not require that Alice and Bob choose
between alternative measurements, therefore improving the rate of generated
bits by transmitted qubit. (b) It allows Alice and Bob to generate a key of
arbitrary length using a single quantum system (three EPR pairs), instead of a
long sequence of them. (c) Detecting Eve requires the comparison of fewer bits.
(d) Entanglement is an essential ingredient. The scheme assumes reliable
measurements of the Bell operator.
| [
{
"version": "v1",
"created": "Sat, 6 Nov 1999 16:08:40 GMT"
},
{
"version": "v2",
"created": "Tue, 3 Oct 2000 20:18:14 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Cabello",
"Adan",
""
]
] |
quant-ph/9911026 | Mikhail Sergeenko | U.P. Sukhatme and M.N. Sergeenko | Semiclassical Approximation for Periodic Potentials | 8 pages, 1 table | null | null | UICHEP-TH/99-8 | quant-ph | null | We derive the semiclassical WKB quantization condition for obtaining the
energy band edges of periodic potentials. The derivation is based on an
approach which is much simpler than the usual method of interpolating with
linear potentials in the regions of the classical turning points. The band
structure of several periodic potentials is computed using our semiclassical
quantization condition.
| [
{
"version": "v1",
"created": "Sat, 6 Nov 1999 21:35:51 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sukhatme",
"U. P.",
""
],
[
"Sergeenko",
"M. N.",
""
]
] |
quant-ph/9911027 | Dagomir Kaszlikowski | Marek Zukowski, Dagomir Kaszlikowski and Emilio Santos | Irrelevance of photon events distinguishability in a class of Bell
experiments | RevTex, 4 pages, 1 figure | Phys. Rev. A, R2614 (1999) | 10.1103/PhysRevA.60.R2614 | null | quant-ph | null | We show that the possibility of distinguishing between single and two photon
detection events, usually not met in the actual experiments, is not a necessary
requirement for the proof that the experiments of Alley and Shih [Phys. Rev.
Lett. 61, 2921 (1988)], and Ou and Mandel [Phys. Rev. Lett. 61, 50 (1988)], are
modulo fair sampling assumption, valid tests of local realism. We also give the
critical parameters for the experiments to be unconditional tests of local
realism, and show that some other interesting phenomena (involving bosonic type
particle indistinguishability) can be observed during such tests.
| [
{
"version": "v1",
"created": "Mon, 8 Nov 1999 15:29:15 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Zukowski",
"Marek",
""
],
[
"Kaszlikowski",
"Dagomir",
""
],
[
"Santos",
"Emilio",
""
]
] |
quant-ph/9911028 | Dagomir Kaszlikowski | Marek Zukowski and Dagomir Kaszlikowski | Faster than light Bell telephone of Michalski transmits only noise | RevTex, 1 page | null | null | null | quant-ph | null | Motivated by pedagogical reasons we pinpoint the mistake in the recent claim,
in quant-ph/9911016, that faster than light communication is possible.
| [
{
"version": "v1",
"created": "Sun, 7 Nov 1999 15:52:28 GMT"
},
{
"version": "v2",
"created": "Mon, 15 Nov 1999 15:44:01 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Zukowski",
"Marek",
""
],
[
"Kaszlikowski",
"Dagomir",
""
]
] |
quant-ph/9911029 | Dae-Yup | Dae-Yup Song | Geometric Phase, Hannay's Angle, and an Exact Action Variable | Submitted to Phys. Rev. Lett. (revised version) | Physical Review Letters 85 (2000) 1141-1145 | 10.1103/PhysRevLett.85.1141 | null | quant-ph | null | Canonical structure of a generalized time-periodic harmonic oscillator is
studied by finding the exact action variable (invariant). Hannay's angle is
defined if closed curves of constant action variables return to the same curves
in phase space after a time evolution. The condition for the existence of
Hannay's angle turns out to be identical to that for the existence of a
complete set of (quasi)periodic wave functions. Hannay's angle is calculated,
and it is shown that Berry's relation of semiclassical origin on geometric
phase and Hannay's angle is exact for the cases considered.
| [
{
"version": "v1",
"created": "Mon, 8 Nov 1999 03:15:15 GMT"
},
{
"version": "v2",
"created": "Thu, 16 Dec 1999 09:06:20 GMT"
},
{
"version": "v3",
"created": "Fri, 25 Aug 2000 09:55:36 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Song",
"Dae-Yup",
""
]
] |
quant-ph/9911030 | Dae-Yup | JeongHyeong Park and Dae-Yup Song | Geometric phases in the simple harmonic and perturbative Mathieu's
oscillator systems | Submitted to J. Phys. A: Math. and Gen. (21 Oct. 1999) | null | null | null | quant-ph | null | Geometric phases of simple harmonic oscillator system are studied. Complete
sets of "eigenfunctions" are constructed, which depend on the way of choosing
classical solutions. For an eigenfunction, two different motions of the
probability distribution function (pulsation of the width and oscillation of
the center) contribute to the geometric phase which can be given in terms of
the parameters of classical solutions. The geometric phase for a general wave
function is also given. If a wave function has a parity under the inversion of
space coordinate, then the geometric phase can be defined under the evolution
of half of the period of classical motions. For the driven case, geometric
phases are given in terms of Fourier coefficients of the external force. The
oscillator systems whose classical equation of motion is Mathieu's equation are
perturbatively studied, and the first term of nonvanishing geometric phase is
calculated.
| [
{
"version": "v1",
"created": "Mon, 8 Nov 1999 03:23:28 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Park",
"JeongHyeong",
""
],
[
"Song",
"Dae-Yup",
""
]
] |
quant-ph/9911031 | Carlo Presilla | Matteo Beccaria, Carlo Presilla, Gian Fabrizio De Angelis, Giovanni
Jona Lasinio | Evolution of fermionic systems as an expectation over Poisson processes | 4 pages, contribution to the proceedings of tenth International
Conference on Recent Progress in Many-Body Theories, Seattle, 1999 | Int.J.Mod.Phys.B15:1740-1743,2001 | 10.1142/S0217979201006276 | null | quant-ph cond-mat hep-lat math-ph math.MP | null | We derive an exact probabilistic representation for the evolution of a
Hubbard model with site- and spin-dependent hopping coefficients and
site-dependent interactions in terms of an associated stochastic dynamics of a
collection of Poisson processes.
| [
{
"version": "v1",
"created": "Mon, 8 Nov 1999 13:13:38 GMT"
}
] | 2011-04-15T00:00:00 | [
[
"Beccaria",
"Matteo",
""
],
[
"Presilla",
"Carlo",
""
],
[
"De Angelis",
"Gian Fabrizio",
""
],
[
"Lasinio",
"Giovanni Jona",
""
]
] |
quant-ph/9911032 | null | G. Brida, M.Genovese and C. Novero | An application of two photon entangled states to quantum metrology | to be published in Journ. of Mod. Opt. As proceeding of "Entanglement
and Decoherence", Gargnano, September 1999 | Jour. Mod. Opt. 47 (2000) 2099 | 10.1080/09500340008235132 | IEN october 1999 | quant-ph physics.optics | null | Besides many interesting application to the study of foundations of quantum
mechanics, entangled state are now assuming a large relevance for some
practical application. In particular, we discuss most recent results obtained
in our laboratory on the use of two photons entangled states produced in
parametric down conversion for absolute quantum efficiency calibration of
photodetectors, in photon counting regime.
| [
{
"version": "v1",
"created": "Mon, 8 Nov 1999 15:47:10 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Brida",
"G.",
""
],
[
"Genovese",
"M.",
""
],
[
"Novero",
"C.",
""
]
] |
quant-ph/9911033 | Slobodan Prvanovic | S. Prvanovic and Z. Maric, Belgrade, Serbia | An Operator Formulation of Classical Mechanics and Semiclassical Limit | 5 pages, no figures | null | null | null | quant-ph | null | The generalized h-dependent operator algebra is defined ($0\leq h \leq h_o$).
For h= h_o it becomes equivalent to the quantum mechanical algebra of
observables and for h=0 it is equivalent to the classical one. We show this by
proposing how the main features of both mechanics can be defined in operator
form.
| [
{
"version": "v1",
"created": "Mon, 8 Nov 1999 15:15:14 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Prvanovic",
"S.",
""
],
[
"Maric",
"Z.",
""
],
[
"Belgrade",
"",
""
],
[
"Serbia",
"",
""
]
] |
quant-ph/9911034 | Anil K. Patnaik | Anil K. Patnaik and G. S. Agarwal (Physical Research Laboratory,
Ahmedabad, India) | Controlling Magneto-Optical Rotation via Atomic COherences | 5 pages, 3 figures, style files included | Frontiers of Laser Physics and Quantum Optics, Eds. Z. Xu, S. Xie,
S.-Y. Zhu and M. O. Scully, pg. 403-407 (Springer, Berlin, 2000) | null | null | quant-ph | null | An isotropic medium, having magnetic sublevels, when subjected to a magnetic
field or an electromagnetic field can induce anisotropy in the medium; and as a
result the plane of polarization of the probe field can rotate. Therefore the
rotation due to the magnetic field alone, can be {\em controlled efficiently}
with use of a coherent field. We show, using a control field, significant
enhancement of the magneto-optical rotation and demonstrate the possibility of
realizing {\em magneto-optical switch}.
| [
{
"version": "v1",
"created": "Tue, 9 Nov 1999 06:54:17 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Patnaik",
"Anil K.",
"",
"Physical Research Laboratory,\n Ahmedabad, India"
],
[
"Agarwal",
"G. S.",
"",
"Physical Research Laboratory,\n Ahmedabad, India"
]
] |
quant-ph/9911035 | Yoshihiro Nambu | Y. Nambu, A. Tomita, Y. Chiba-Kohno and K. Nakamura (Fundamental Res.
Labs., NEC Corporation, Japan) | Quantum Key Distribution using Two Coherent States of Light and their
Superposition | 20 pages, 4 figures, RevTeX, submitted to PRA, Revised 2000/2/23 | Phys. Rev. A62, 012312 (2000) | 10.1103/PhysRevA.62.012312 | PRDG-43599 | quant-ph | null | Quantum mechanical complementarity ensures the security of the
key-distribution scheme reported by Brassard and Bennet in 1984 (BB84), but
does not prohibit use of multi-photons as a signal carrier. We describe a novel
BB84 scheme in which two nearly orthogonal coherent states carry the key, and
the superposition of these states (cat states) protects the communication
channel from eavesdropping. Information leakage to eavesdroppers can be
determined from the visibility of the interferential fringes in the
distribution of the outcome when a certain quadrature component is measured
through homodyne detection. The effect of channel loss and detector
inefficiency is discussed.
| [
{
"version": "v1",
"created": "Tue, 9 Nov 1999 09:14:00 GMT"
},
{
"version": "v2",
"created": "Wed, 23 Feb 2000 08:53:30 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Nambu",
"Y.",
"",
"Fundamental Res.\n Labs., NEC Corporation, Japan"
],
[
"Tomita",
"A.",
"",
"Fundamental Res.\n Labs., NEC Corporation, Japan"
],
[
"Chiba-Kohno",
"Y.",
"",
"Fundamental Res.\n Labs., NEC Corporation, Japan"
],
[
"Nakamura",
"K.",
"",
"Fundamental Res.\n Labs., NEC Corporation, Japan"
]
] |
quant-ph/9911036 | Matteo G. A. Paris | MGA Paris, M Plenio, D Jonathan, S Bose and GM D'Ariano | Optical Bell Measurement by Fock Filtering | 8 pages, 2 figures | Physics Letters A 273 (2000) 153-158 | 10.1016/S0375-9601(00)00477-1 | null | quant-ph | null | We describe a nonlinear interferometric setup to perform a complete optical
Bell measurement, i.e. to unambigously discriminate the four polarization
entangled EPR-Bell photon pairs. The scheme is robust against detector
inefficiency.
| [
{
"version": "v1",
"created": "Tue, 9 Nov 1999 10:47:03 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Paris",
"MGA",
""
],
[
"Plenio",
"M",
""
],
[
"Jonathan",
"D",
""
],
[
"Bose",
"S",
""
],
[
"D'Ariano",
"GM",
""
]
] |
quant-ph/9911037 | Anthony Hams | H. De Raedt, A.H. Hams, K. Michielsen, S. Miyashita, K. Saito | Quantum Statistical Mechanics on a Quantum Computer | 6 pages, 2 figures, PTPTEX (included) | null | null | null | quant-ph | null | We describe a quantum algorithm to compute the density of states and thermal
equilibrium properties of quantum many-body systems. We present results
obtained by running this algorithm on a software implementation of a 21-qubit
quantum computer for the case of an antiferromagnetic Heisenberg model on
triangular lattices of different size.
| [
{
"version": "v1",
"created": "Tue, 9 Nov 1999 14:33:52 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"De Raedt",
"H.",
""
],
[
"Hams",
"A. H.",
""
],
[
"Michielsen",
"K.",
""
],
[
"Miyashita",
"S.",
""
],
[
"Saito",
"K.",
""
]
] |
quant-ph/9911038 | Anthony Hams | H. De Raedt, A.H. Hams, K. Michielsen, S. Miyashita, K.Saito | Quantum Spin Dynamics and Quantum Computation | 6 pages, 4 figures ; Minor errors corrected and figures updated | null | null | null | quant-ph | null | We describe a simulation method for a quantum spin model of a generic,
general purpose quantum computer. The use of this quantum computer simulator is
illustrated through several implementations of Grover's database search
algorithm. Some preliminary results on the stability of quantum algorithms are
presented.
| [
{
"version": "v1",
"created": "Tue, 9 Nov 1999 14:44:50 GMT"
},
{
"version": "v2",
"created": "Fri, 14 Jan 2000 13:59:21 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"De Raedt",
"H.",
""
],
[
"Hams",
"A. H.",
""
],
[
"Michielsen",
"K.",
""
],
[
"Miyashita",
"S.",
""
],
[
"Saito",
"K.",
""
]
] |
quant-ph/9911039 | Dagomir Kaszlikowski | Marek Zukowski and Dagomir Kaszlikowski | Greenberger-Horne-Zeilinger paradoxes with symmetric multiport beam
splitters | RevTex, 8 pages | Phys. Rev. A 59, 3200 (1999) | 10.1103/PhysRevA.59.3200 | null | quant-ph | null | In a gedankenexperiment N particles in a generalized GHZ-type beam entangled
state (each particle can be in one of M beams) are fed into N symmetric 2M-port
beam splitters (spatially separated). Correlation functions for such a process
(using the Bell numbers value assignment approach) reveal a remarkable
symmetry. For N=M+1 greater or equal to 4 a series of GHZ paradoxes are shown.
| [
{
"version": "v1",
"created": "Tue, 9 Nov 1999 15:17:15 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Zukowski",
"Marek",
""
],
[
"Kaszlikowski",
"Dagomir",
""
]
] |
quant-ph/9911040 | Svozil Karl | Hans Havlicek, Guenther Krenn, Johann Summhammer and Karl Svozil | Coloring the rational quantum sphere and the Kochen-Specker theorem | 9 pages, 1 figure | J. Phys. A: Math. Gen. 34(14), 3071-3077 (13 April 2001) | null | null | quant-ph | null | We review and extend recent findings of Godsil and Zaks, who published a
constructive coloring of the rational unit sphere with the property that for
any orthogonal tripod formed by rays extending from the origin of the points of
the sphere, exactly one ray is red, white and black. They also showed that any
consistent coloring of the real sphere requires an additional color. We discuss
some of the consequences for the Kochen-Specker theorem.
| [
{
"version": "v1",
"created": "Tue, 9 Nov 1999 16:24:12 GMT"
},
{
"version": "v2",
"created": "Mon, 11 Jun 2001 08:31:56 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Havlicek",
"Hans",
""
],
[
"Krenn",
"Guenther",
""
],
[
"Summhammer",
"Johann",
""
],
[
"Svozil",
"Karl",
""
]
] |
quant-ph/9911041 | Anthony Hams | Hans De Raedt, Anthony Hams, Kristel Michielsen, Koen De Raedt | Quantum Computer Emulator | 28 pages, 4, figures, see also
http://rugth30.phys.rug.nl/compphys/qce.htm ; figures updated, instructions
changed | null | 10.1016/S0010-4655(00)00132-6 | null | quant-ph | null | We describe a quantum computer emulator for a generic, general purpose
quantum computer. This emulator consists of a simulator of the physical
realization of the quantum computer and a graphical user interface to program
and control the simulator. We illustrate the use of the quantum computer
emulator through various implementations of the Deutsch-Jozsa and Grover's
database search algorithm.
| [
{
"version": "v1",
"created": "Tue, 9 Nov 1999 16:47:03 GMT"
},
{
"version": "v2",
"created": "Wed, 29 Mar 2000 10:09:44 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"De Raedt",
"Hans",
""
],
[
"Hams",
"Anthony",
""
],
[
"Michielsen",
"Kristel",
""
],
[
"De Raedt",
"Koen",
""
]
] |
quant-ph/9911042 | Christiane Koch | Christiane Koch and Bernd Esser | Spin-Boson Hamiltonian and Optical Absorption of Molecular Dimers | 15 pages, revTeX, 8 figures, accepted for publication in Phys. Rev. A | Phys. Rev. A 61, 022508 (2000) | 10.1103/PhysRevA.61.022508 | null | quant-ph | null | An analysis of the eigenstates of a symmetry-broken spin-boson Hamiltonian is
performed by computing Bloch and Husimi projections. The eigenstate analysis is
combined with the calculation of absorption bands of asymmetric dimer
configurations constituted by monomers with nonidentical excitation energies
and optical transition matrix elements. Absorption bands with regular and
irregular fine structures are obtained and related to the transition from the
coexistence to a mixing of adiabatic branches in the spectrum. It is shown that
correlations between spin states allow for an interpolation between absorption
bands for different optical asymmetries.
| [
{
"version": "v1",
"created": "Tue, 9 Nov 1999 17:12:17 GMT"
}
] | 2012-04-20T00:00:00 | [
[
"Koch",
"Christiane",
""
],
[
"Esser",
"Bernd",
""
]
] |
quant-ph/9911043 | Lucien Hardy | Lucien Hardy (The Perimeter Institute) and Adrian Kent (Centre for
Quantum Computation, University of Cambridge) | Cheat Sensitive Quantum Bit Commitment | Final version: a slightly shortened version of this will appear in
PRL. Minor corrections from last version | Phys. Rev. Lett. 92, 157901 (2004). | 10.1103/PhysRevLett.92.157901 | null | quant-ph cs.CR | null | We define cheat sensitive cryptographic protocols between mistrustful parties
as protocols which guarantee that, if either cheats, the other has some nonzero
probability of detecting the cheating. We give an example of an unconditionally
secure cheat sensitive non-relativistic bit commitment protocol which uses
quantum information to implement a task which is classically impossible; we
also describe a simple relativistic protocol.
| [
{
"version": "v1",
"created": "Tue, 9 Nov 1999 22:53:16 GMT"
},
{
"version": "v2",
"created": "Wed, 10 Nov 1999 20:02:33 GMT"
},
{
"version": "v3",
"created": "Mon, 26 Jun 2000 15:26:05 GMT"
},
{
"version": "v4",
"created": "Wed, 2 Jul 2003 12:33:31 GMT"
},
{
"version": "v5",
"created": "Wed, 3 Mar 2004 18:59:50 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Hardy",
"Lucien",
"",
"The Perimeter Institute"
],
[
"Kent",
"Adrian",
"",
"Centre for\n Quantum Computation, University of Cambridge"
]
] |
quant-ph/9911044 | Duer Wolfgang | W. D\"ur and J. I. Cirac | Classification of multi-qubit mixed states: separability and
distillability properties | 12 pages, 2 figures | Phys. Rev. A 61, 042314 (2000) | 10.1103/PhysRevA.61.042314 | null | quant-ph | null | We give a complete, hierarchic classification for arbitrary multi-qubit mixed
states based on the separability properties of certain partitions. We introduce
a family of N-qubit states to which any arbitrary state can be depolarized.
This family can be viewed as the generalization of Werner states to multi-qubit
systems. We fully classify those states with respect to their separability and
distillability properties. This provides sufficient conditions for
nonseparability and distillability for arbitrary states.
| [
{
"version": "v1",
"created": "Wed, 10 Nov 1999 11:18:51 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Dür",
"W.",
""
],
[
"Cirac",
"J. I.",
""
]
] |
quant-ph/9911045 | Dagomir Kaszlikowski | Marek Zukowski and Dagomir Kaszlikowski | Entanglement swapping with PDC sources | RevTex, 5 pages, 1 figure | acta physica slovaca vol. 49 No. 4, 621-626 | null | null | quant-ph | null | We show that the possibility of distinguishing between single and two photon
detection events is not a necessary requirement for the proof that recent
operational realization of entanglement swapping cannot find a local realistic
description. We propose a simple modification of the experiment, which gives a
richer set of interesting phenomena.
| [
{
"version": "v1",
"created": "Wed, 10 Nov 1999 16:42:44 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Zukowski",
"Marek",
""
],
[
"Kaszlikowski",
"Dagomir",
""
]
] |
quant-ph/9911046 | Alexander Gersten | A. Gersten | Orthogonality and Boundary Conditions in Quantum Mechanics | 10 pages, LaTex | Found. Phys. Lett. 11, 251-4 (1998) | null | null | quant-ph | null | One-dimensional particle states are constructed according to orthogonality
conditions, without requiring boundary conditions. Free particle states are
constructed using Dirac's delta function orthogonality conditions. The states
(doublets) depend on two quantum numbers: energy and parity. With the aid of
projection operators the particles are confined to a constrained region, in a
way similar to the action of an infinite well potential. From the resulting
overcomplete basis only the mutually orthogonal states are selected. Four
solutions are found, corresponding to different non-commuting Hamiltonians.
Their energy eigenstates are labeled with the main quantum number n and parity
"+" or "-". The energy eigenvalues are functions of n only. The four cases
correspond to different boundary conditions: (I) the wave function vanishes on
the boundary, (II) the derivative of the wavefunction vanishes on the
boundary,(III) periodic (symmetric) boundary conditions, (IV) periodic
(antisymmetric)boundary conditions . Among the four cases, only solution (III)
forms a complete basis in the sense that any function in the constrained
region, can be expanded with it. By extending the boundaries of the constrained
region to infinity, only solution (III) converges uniformly to the free
particle states. Orthogonality seems to be a more basic requirement than
boundary conditions. By using projection operators, confinement of the particle
to a definite region can be achieved in a conceptually simple and unambiguous
way, and physical operators can be written so that they act only in the
confined region.
| [
{
"version": "v1",
"created": "Wed, 10 Nov 1999 22:11:41 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gersten",
"A.",
""
]
] |
quant-ph/9911047 | Alexander Gersten | A. Gersten | Incomplete Delta Functions | 11 pages, LaTex | Found. Phys. Lett. 11, 165-178 (1998) | null | null | quant-ph | null | By applying projection operators to state vectors of coordinates we obtain
subspaces in which these states are no longer normalized according to Dirac's
delta function but normalized according to what we call "incomplete delta
functions". We show that this class of functions satisfy identities similar to
those satisfied by the Dirac delta function. The incomplete delta functions may
be employed advantageously in projected subspaces and in the link between
functions defined on the whole space and the projected subspace. We apply a
similar procedure to finite dimensional vector spaces for which we define
incomplete Kronecker deltas. Dispersion relations for the momenta are obtained
and ''sums over poles'' are defined and obtained with the aid of differences of
incomplete delta functions.
| [
{
"version": "v1",
"created": "Wed, 10 Nov 1999 22:28:57 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gersten",
"A.",
""
]
] |
quant-ph/9911048 | Volodymyr Tkachuk | V. M. Tkachuk and P. Roy | Motion of a spin 1/2 particle in shape invariant scalar and magnetic
fields | 14 pages | null | 10.1088/0305-4470/33/22/317 | null | quant-ph | null | We study the motion of a spin 1/2 particle in a scalar as well as a magnetic
field within the framework of supersymmetric quantum mechanics(SUSYQM). We also
introduce the concept of shape invariant scalar and magnetic fields and it is
shown that the problem admits exact analytical solutions when such fields are
considered.
| [
{
"version": "v1",
"created": "Thu, 11 Nov 1999 15:48:50 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Tkachuk",
"V. M.",
""
],
[
"Roy",
"P.",
""
]
] |
quant-ph/9911049 | Alexander Gersten | A. Gersten | Maxwell equations as the one-photon quantum equation | 9 pages, LaTex | Found. Phys. Lett. 12, 291-8 (1999) | null | null | quant-ph | null | Maxwell equations (Faraday and Ampere-Maxwell laws) can be presented as a
three component equation in a way similar to the two component neutrino
equation. However, in this case, the electric and magnetic Gauss's laws can not
be derived from first principles. We have shown how all Maxwell equations can
be derived simultaneously from first principles, similar to those which have
been used to derive the Dirac relativistic electron equation. We have also
shown that equations for massless particles, derived by Dirac in 1936, lead to
the same result. The complex wave function, being a linear combination of the
electric and magnetic fields, is a locally measurable and well understood
quantity. Therefore Maxwell equations should be used as a guideline for proper
interpretations of quantum theories.
| [
{
"version": "v1",
"created": "Thu, 11 Nov 1999 17:58:44 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gersten",
"A.",
""
]
] |
quant-ph/9911050 | Stephen A. Fulling | S. A. Fulling | A Possible New Quantum Algorithm: Arithmetic with Large Integers via the
Chinese Remainder Theorem | 4 pages; plain TeX with vanilla.sty and pictex.tex macros | null | null | null | quant-ph | null | Residue arithmetic is an elegant and convenient way of computing with
integers that exceed the natural word size of a computer. The algorithms are
highly parallel and hence naturally adapted to quantum computation. The process
differs from most quantum algorithms currently under discussion in that the
output would presumably be obtained by classical superposition of the output of
many identical quantum systems, instead of by arranging for constructive
interference in the wave function of a single quantum computer.
| [
{
"version": "v1",
"created": "Thu, 11 Nov 1999 20:05:40 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Fulling",
"S. A.",
""
]
] |
quant-ph/9911051 | Stephen A. Fulling | S. A. Fulling | Large Numbers, the Chinese Remainder Theorem, and the Circle of Fifths | 9 pages; Plain TeX with vanilla.sty and pictex.tex macros | Phys. Rev. Applied 13, 024016 (2020) | 10.1103/PhysRevApplied.13.024016 | null | quant-ph | null | This is a pedagogical article cited in the foregoing research note,
quant-ph/9911050
| [
{
"version": "v1",
"created": "Thu, 11 Nov 1999 20:12:50 GMT"
}
] | 2020-02-12T00:00:00 | [
[
"Fulling",
"S. A.",
""
]
] |
quant-ph/9911052 | Brian C. Hall | Brian C. Hall | Coherent states, Yang-Mills theory, and reduction | null | null | null | null | quant-ph hep-th math-ph math.MP | null | This paper explains some of the ideas behind a prior joint work of the author
with Bruce Driver on the canonical quantization of Yang-Mills theory on a
spacetime cylinder. The idea is that the generalized Segal-Bargmann transform
for a compact group can be obtained from the ordinary Segal-Bargmann transform
by imposing gauge symmetry.
| [
{
"version": "v1",
"created": "Thu, 11 Nov 1999 20:55:34 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Hall",
"Brian C.",
""
]
] |
quant-ph/9911053 | Jae-Seung Lee | Jae-Seung Lee, Yongwook Chung, Jaehyun Kim, Soonchil Lee | A Practical Method of Constructing Quantum Combinational Logic Circuits | REVTeX, 10 pages, 3 figures | null | null | null | quant-ph | null | We describe a practical method of constructing quantum combinational logic
circuits with basic quantum logic gates such as NOT and general $n$-bit Toffoli
gates. This method is useful to find the quantum circuits for evaluating logic
functions in the form most appropriate for implementation on a given quantum
computer. The rules to get the most efficient circuit are utilized best with
the aid of a Karnaugh map. It is explained which rules of using a Karnaugh map
are changed due to the difference between the quantum and classical logic
circuits.
| [
{
"version": "v1",
"created": "Fri, 12 Nov 1999 06:13:34 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Lee",
"Jae-Seung",
""
],
[
"Chung",
"Yongwook",
""
],
[
"Kim",
"Jaehyun",
""
],
[
"Lee",
"Soonchil",
""
]
] |
quant-ph/9911054 | Norbert Luetkenhaus | Gilles Brassard, Norbert L\"utkenhaus, Tal Mor, and Barry C. Sanders | Security Aspects of Practical Quantum Cryptography | 5 pages, uses multicol | Phys. Rev. Lett. Vol 85, 1330-1333 (2000). | 10.1103/PhysRevLett.85.1330 | null | quant-ph | null | The use of quantum bits (qubits) in cryptography holds the promise of secure
cryptographic quantum key distribution schemes. Unfortunately, the implemented
schemes can be totally insecure. We provide a thorough investigation of
security issues for practical quantum key distribution, taking into account
channel losses, a realistic detection process, and modifications of the
``qubits'' sent from the sender to the receiver. We first show that even
quantum key distribution with perfect qubits cannot be achieved over long
distances when fixed channel losses and fixed dark count errors are taken into
account. Then we show that existing experimental schemes (based on
``weak-pulse'') are usually totally insecure. Finally we show that parametric
downconversion offers enhanced performance compared to its weak coherent pulse
counterpart.
| [
{
"version": "v1",
"created": "Fri, 12 Nov 1999 08:32:27 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Brassard",
"Gilles",
""
],
[
"Lütkenhaus",
"Norbert",
""
],
[
"Mor",
"Tal",
""
],
[
"Sanders",
"Barry C.",
""
]
] |
quant-ph/9911055 | Molotkov S. | S.N.Molotkov and S.S.Nazin (Institute of Solid State Physics, Russian
Academy of Sciences) | Unconditionally Secure Relativistic Quantum Bit Commitment | 12 pages, no figures | null | null | null | quant-ph | null | A new relativistic quantum protocol is proposed allowing to implement the bit
commitment scheme. The protocol is based on the idea that in the relativistic
case the field propagation to the region of space accessible to measurement
requires, contrary to the non-relativistic case, a finite non-zero time which
depends on the structure of the particular state of the field. In principle,
the secret bit can be stored for arbitrarily long time with the probability
arbitrarily close to unit.
| [
{
"version": "v1",
"created": "Fri, 12 Nov 1999 11:15:30 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Molotkov",
"S. N.",
"",
"Institute of Solid State Physics, Russian\n Academy of Sciences"
],
[
"Nazin",
"S. S.",
"",
"Institute of Solid State Physics, Russian\n Academy of Sciences"
]
] |
quant-ph/9911056 | Dr Dagmar Bruss | Dagmar Bruss and Asher Peres | Construction of quantum states with bound entanglement | 5 pages | Phys. Rev. A 61, 30301(R) (2000) | 10.1103/PhysRevA.61.030301 | null | quant-ph | null | We present a new family of bound-entangled quantum states in 3x3 dimensions.
Their density matrix depends on 7 independent parameters and has 4 different
non-vanishing eigenvalues.
| [
{
"version": "v1",
"created": "Fri, 12 Nov 1999 13:33:39 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Bruss",
"Dagmar",
""
],
[
"Peres",
"Asher",
""
]
] |
quant-ph/9911057 | Barbara M. Terhal | Barbara M. Terhal | Bell Inequalities and the Separability Criterion | 16 pages Revtex, typo in equation (14) corrected | Physics Letters A Vol. 271, 319 (2000) | 10.1016/S0375-9601(00)00401-1 | null | quant-ph | null | We analyze and compare the mathematical formulations of the criterion for
separability for bipartite density matrices and the Bell inequalities. We show
that a violation of a Bell inequality can formally be expressed as a witness
for entanglement. We also show how the criterion for separability and a
description of the state by a local hidden variable theory, become equivalent
when we restrict the set of local hidden variable theories to the domain of
quantum mechanics. This analysis sheds light on the essential difference
between the two criteria and may help us in understanding whether there exist
entangled states for which the statistics of the outcomes of all possible local
measurements can be described by a local hidden variable theory.
| [
{
"version": "v1",
"created": "Fri, 12 Nov 1999 17:33:34 GMT"
},
{
"version": "v2",
"created": "Tue, 23 Nov 1999 17:10:09 GMT"
},
{
"version": "v3",
"created": "Fri, 26 May 2000 15:35:03 GMT"
},
{
"version": "v4",
"created": "Mon, 27 Nov 2000 15:55:37 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Terhal",
"Barbara M.",
""
]
] |
quant-ph/9911058 | Paul Slater | Paul B. Slater (University of California) | Exact Bures Probabilities that Two Quantum Bits are Classically
Correlated | Seventeen pages, LaTeX, eleven postscript figures. In this version,
subsequent (!) to publication in European Physical Journal B, we correct the
(1,1)-entries of the 4 x 4 matrices given in formulas (6) and (7), that is,
the numerators should both read v^2 - x^2 - y^2 - z^2, rather than v^2 - x^2
+ y^2 + z^2 | European Physical Journal B, Oct. 2000, vol. 17 (no.3):471-80 | 10.1007/s100510070126 | null | quant-ph math-ph math.MP physics.data-an | null | In previous studies, we have explored the ansatz that the volume elements of
the Bures metrics over quantum systems might serve as prior distributions, in
analogy to the (classical) Bayesian role of the volume elements ("Jeffreys'
priors") of Fisher information metrics. Continuing this work, we obtain exact
Bures probabilities that the members of certain low-dimensional subsets of the
fifteen-dimensional convex set of 4 x 4 density matrices are separable or
classically correlated. The main analytical tools employed are symbolic
integration and a formula of Dittmann (quant-ph/9908044) for Bures metric
tensors. This study complements an earlier one (quant-ph/9810026) in which
numerical (randomization) --- but not integration --- methods were used to
estimate Bures separability probabilities for unrestricted 4 x 4 or 6 x 6
density matrices. The exact values adduced here for pairs of quantum bits
(qubits), typically, well exceed the estimate (.1) there, but this disparity
may be attributable to our focus on special low-dimensional subsets. Quite
remarkably, for the q = 1 and q = 1/2 states inferred using the principle of
maximum nonadditive (Tsallis) entropy, the separability probabilities are both
equal to 2^{1/2} - 1. For the Werner qubit-qutrit and qutrit-qutrit states, the
probabilities are vanishingly small, while in the qubit-qubit case it is 1/4.
| [
{
"version": "v1",
"created": "Fri, 12 Nov 1999 23:00:58 GMT"
},
{
"version": "v2",
"created": "Sun, 14 Nov 1999 23:21:51 GMT"
},
{
"version": "v3",
"created": "Thu, 18 Nov 1999 19:52:32 GMT"
},
{
"version": "v4",
"created": "Fri, 10 Dec 1999 22:22:46 GMT"
},
{
"version": "v5",
"created": "Thu, 24 Feb 2000 20:06:54 GMT"
},
{
"version": "v6",
"created": "Thu, 22 Jun 2000 21:22:21 GMT"
},
{
"version": "v7",
"created": "Thu, 11 Jan 2001 17:18:32 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Slater",
"Paul B.",
"",
"University of California"
]
] |
quant-ph/9911059 | Taksu Cheon de Caracorum | T. Shigehara, H. Mizoguchi, T. Mishima (Saitama U) and Taksu Cheon
(Kochi Tech) | Generalized One-Dimensional Point Interaction in Relativistic and
Non-relativistic Quantum Mechanics | LaTeX 4 Pages, Talk to be presented at The 1999 International
Symposium on Nonlinear Theory and Its Applications (NOLTA99) Hilton Waikoloa
Village, Hawaii, USA, Nov 28 - Dec 2, 1999 | null | null | null | quant-ph | null | We first give the solution for the local approximation of a four parameter
family of generalized one-dimensional point interactions within the framework
of non-relativistic model with three neighboring $\delta$ functions. We also
discuss the problem within relativistic (Dirac) framework and give the solution
for a three parameter family. It gives a physical interpretation for so-called
$\epsilon$ potential. It will be also shown that the scattering properties at
high energy substantially differ between non-relativistic and relativistic
cases.
| [
{
"version": "v1",
"created": "Sat, 13 Nov 1999 07:47:15 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Shigehara",
"T.",
"",
"Saitama U"
],
[
"Mizoguchi",
"H.",
"",
"Saitama U"
],
[
"Mishima",
"T.",
"",
"Saitama U"
],
[
"Cheon",
"Taksu",
"",
"Kochi Tech"
]
] |
quant-ph/9911060 | Pavel Exner | Pavel Exner, Vladimir A. Geyler | Berry phase in magnetic systems with point perturbations | LaTeX, 26 pages | J. Geom. Phys. 36 (2000), 178-197 | 10.1016/S0393-0440(00)00020-6 | null | quant-ph cond-mat math-ph math.MP | null | We study a two-dimensional charged particle interacting with a magnetic
field, in general non-homogeneous, perpendicular to the plane, a confining
potential, and a point interaction. If the latter moves adiabatically along a
loop the state corresponding to an isolated eigenvalue acquires a Berry phase.
We derive an expression for it and evaluate it in several examples such as a
homogeneous field, a magnetic whisker, a particle confined at a ring or in
quantum dots, a parabolic and a zero-range one. We also discuss the behavior of
the lowest Landau level in this setting obtaining an explicit example of the
Wilczek-Zee phase for an infinitely degenerated eigenvalue.
| [
{
"version": "v1",
"created": "Sat, 13 Nov 1999 11:10:05 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Exner",
"Pavel",
""
],
[
"Geyler",
"Vladimir A.",
""
]
] |
quant-ph/9911061 | Victor Flambaum | V.V. Flambaum | Time dynamics in chaotic many-body systems: can chaos destroy a quantum
computer? | 9 pages, RevTex | null | null | null | quant-ph chao-dyn cond-mat.mes-hall cond-mat.stat-mech nlin.CD nucl-th physics.atom-ph | null | Highly excited many-particle states in quantum systems (nuclei, atoms,
quantum dots, spin systems, quantum computers) can be ``chaotic''
superpositions of mean-field basis states (Slater determinants, products of
spin or qubit states). This is a result of the very high energy level density
of many-body states which can be easily mixed by a residual interaction between
particles. We consider the time dynamics of wave functions and increase of
entropy in such chaotic systems.
As an example we present the time evolution in a closed quantum computer. A
time scale for the entropy S(t) increase is t_c =t_0/(n log_2{n}), where t_0 is
the qubit ``lifetime'', n is the number of qubits, S(0)=0 and S(t_c)=1. At t <<
t_c the entropy is small: S= n t^2 J^2 log_2(1/t^2 J^2), where J is the
inter-qubit interaction strength. At t > t_c the number of ``wrong'' states
increases exponentially as 2^{S(t)} . Therefore, t_c may be interpreted as a
maximal time for operation of a quantum computer, since at t > t_c one has to
struggle against the second law of thermodynamics. At t >>t_c the system
entropy approaches that for chaotic eigenstates.
| [
{
"version": "v1",
"created": "Mon, 15 Nov 1999 02:57:05 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Flambaum",
"V. V.",
""
]
] |
quant-ph/9911062 | Igor V. Volovich | I.V. Volovich | Atomic Quantum Computer | 5 pages, Latex | null | null | null | quant-ph cond-mat.mes-hall physics.atom-ph | null | The current proposals for the realization of quantum computer such as NMR,
quantum dots and trapped ions are based on the using of an atom or an ion as
one qubit. In these proposals a quantum computer consists from several atoms
and the coupling between them provides the coupling between qubits necessary
for a quantum gate. We discuss whether a {\it single} atom can be used as a
quantum computer. Internal states of the atom serve to hold the quantum
information and the spin-orbit and spin-spin interaction provides the coupling
between qubits in the atomic quantum computer. In particular one can use the
electron spin resonance (ESR) to process the information encoded in the
hyperfine splitting of atomic energy levels. By using quantum state engineering
one can manipulate the internal states of the natural or artificial (quantum
dot) atom to make quantum computations.
| [
{
"version": "v1",
"created": "Sun, 14 Nov 1999 04:23:53 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Volovich",
"I. V.",
""
]
] |
quant-ph/9911063 | LiXiang Li | Zheng-Wei Zhou and Guang-Can Guo (University of Science and Technology
of China) | Disentanglement and Inseparability correlation : in two-qubit system | 10 Pages, 2 Figures, REVTeX; to appear in PRA | null | 10.1103/PhysRevA.61.032108 | null | quant-ph | null | Started from local universal isotropic disentanglement, a threshold
inequality on reduction factors is proposed, which is necessary and sufficient
for this type of disentanglement processes. Furthermore, we give the conditions
realizing ideal disentanglement processes provided that some information on
quantum states is known. In addition, based on fully entangled fraction, a
concept called inseparability correlation is presented. Some properties on
inseparability correlation coefficient are studied.
| [
{
"version": "v1",
"created": "Sun, 14 Nov 1999 13:07:58 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Zhou",
"Zheng-Wei",
"",
"University of Science and Technology\n of China"
],
[
"Guo",
"Guang-Can",
"",
"University of Science and Technology\n of China"
]
] |
quant-ph/9911064 | C. Y. Chen | C.Y. Chen | Time-dependent Perturbation Theory in Quantum Mechanics | 13 pages, No figures | null | null | null | quant-ph | null | After revealing difficulties of the standard time-dependent perturbation
theory in quantum mechanics mainly from the viewpoint of practical calculation,
we propose a new quasi-canonical perturbation theory. In the new theory, the
dynamics of physical observables, instead of that of coefficients of
wave-function expansion, is formulated so that the gauge-invariance and
correspondence principles are observed naturally.
| [
{
"version": "v1",
"created": "Sun, 14 Nov 1999 14:29:15 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Chen",
"C. Y.",
""
]
] |
quant-ph/9911065 | Spohn | Herbert Spohn | Semiclassical limit of the Dirac equation and spin precession | null | null | 10.1006/aphy.2000.6039 | null | quant-ph | null | We study the Dirac equation with slowly varying external potentials. Using
matrix-valued Wigner functions we prove that the electron follows with high
precision the classical orbit and that the spin precesses according to the BMT
equation with gyromagnetic ratio g=2.
| [
{
"version": "v1",
"created": "Sun, 14 Nov 1999 16:37:45 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Spohn",
"Herbert",
""
]
] |
quant-ph/9911066 | Klaus Morawetz | Klaus Morawetz, V\'aclav \v{S}pi\v{c}ka, Pavel Lipavsk\'y | Nonlocal kinetic theory | Proceedings KB99 Workshop, September 20-24 1999, Rostock, Germany | null | 10.1142/9789812792754_0054 | null | quant-ph | null | The short time behavior of a disturbed system is influenced by off-shell
motion and best characterized by the reduced density matrix possessing high
energetic tails. We present analytically the formation of correlations due to
collisions in an interacting Fermionic system with and without initial
correlation. After this short time regime the time evolution is controlled by
small gradients. This leads to a nonlocal Boltzmann equation for the
quasiparticle distribution and a functional relating the latter one to the
reduced density matrix. The nonlocalities are presented as time and space
shifts arising from gradient expansion and are leading to virial corrections in
the thermodynamical limit.
| [
{
"version": "v1",
"created": "Mon, 15 Nov 1999 08:11:48 GMT"
}
] | 2016-11-23T00:00:00 | [
[
"Morawetz",
"Klaus",
""
],
[
"Špička",
"Václav",
""
],
[
"Lipavský",
"Pavel",
""
]
] |
quant-ph/9911067 | Hradil Zdenek | Z. Hradil, J. Summhammer | Quantum theory of incompatible observations | 3 pages | null | 10.1088/0305-4470/33/42/309 | null | quant-ph | null | Maximum likelihood principle is shown to be the best measure for relating the
experimental data with the predictions of quantum theory.
| [
{
"version": "v1",
"created": "Mon, 15 Nov 1999 11:58:21 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Hradil",
"Z.",
""
],
[
"Summhammer",
"J.",
""
]
] |
quant-ph/9911068 | Hradil Zdenek | Z. Hradil, J. Summhammer, G. Badurek, H. Rauch | Reconstruction of the spin state | 4 pages, 1 figure | null | 10.1103/PhysRevA.62.014101 | null | quant-ph | null | System of 1/2 spin particles is observed repeatedly using Stern-Gerlach
apparatuses with rotated orientations. Synthesis of such non-commuting
observables is analyzed using maximum likelihood estimation as an example of
quantum state reconstruction. Repeated incompatible observations represent a
new generalized measurement. This idealized scheme will serve for analysis of
future experiments in neutron and quantum optics.
| [
{
"version": "v1",
"created": "Mon, 15 Nov 1999 13:52:56 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Hradil",
"Z.",
""
],
[
"Summhammer",
"J.",
""
],
[
"Badurek",
"G.",
""
],
[
"Rauch",
"H.",
""
]
] |
quant-ph/9911069 | David Vitali | Stefano Mancini, David Vitali and Paolo Tombesi | Motional Squashed States | 8 pages, 2 figures, to appear in the special Issue "Quantum
Correlations and Fluctuations" of J. Opt. B | J. Opt. B: Quantum Semiclass. Opt. 2, 190 (2000) | 10.1088/1464-4266/2/2/322 | null | quant-ph | null | We show that by using a feedback loop it is possible to reduce the
fluctuations in one quadrature of the vibrational degree of freedom of a
trapped ion below the quantum limit. The stationary state is not a proper
squeezed state, but rather a ``squashed'' state, since the uncertainty in the
orthogonal quadrature, which is larger than the standard quantum limit, is
unaffected by the feedback action.
| [
{
"version": "v1",
"created": "Mon, 15 Nov 1999 14:13:29 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Mancini",
"Stefano",
""
],
[
"Vitali",
"David",
""
],
[
"Tombesi",
"Paolo",
""
]
] |
quant-ph/9911070 | Garnik F. Mkrtchian | H. K. Avetissian, A. G. Markossian and G. F. Mkrtchian (Yerevan State
University, Yerevan, Armenia) | Relativistic theory of the above-threshold multiphoton ionization of
hydrogen-like atoms in the ultrastrong laser fields | REVTeX, 13 pages | null | null | null | quant-ph | null | The relativistic theory of above-threshold ionization (ATI) of hydrogen-like
atoms in ultrastrong radiation fields, taking into account the photoelectron
induced rescattering in the continuum spectrum is developed. It is shown that
the contribution of the latter in the multiphoton ionization probability even
in the Born approximation by Coulomb field is of the order of ATI probability
in the scope of Keldysh-Faisal-Reiss ansatz.
| [
{
"version": "v1",
"created": "Tue, 16 Nov 1999 13:36:47 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Avetissian",
"H. K.",
"",
"Yerevan State\n University, Yerevan, Armenia"
],
[
"Markossian",
"A. G.",
"",
"Yerevan State\n University, Yerevan, Armenia"
],
[
"Mkrtchian",
"G. F.",
"",
"Yerevan State\n University, Yerevan, Armenia"
]
] |
quant-ph/9911071 | Hradil Zdenek | Z. Hradil and M. Dusek | Analogy between optimal spin estimation and interferometry | 5 pages | null | 10.1016/S0030-4018(00)00809-9 | null | quant-ph | null | Scheme for optimal spin state estimation is considered in analogy with phase
detection in interferometry. Recently reported coherent measurements yielding
the average fidelity (N+1)/(N+2) for N particle system corresponds to the
standard limit of phase resolution 1/\sqrt{N}. It provides the bound for
incoherent measurements when each particle is detected separately and
information is used optimally. For specific states, improvement up to the value
1/N is possible in quantum theory. The best results are obtained combining
sequentially coherent measurements on fractional groups of particles.
| [
{
"version": "v1",
"created": "Tue, 16 Nov 1999 14:01:47 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Hradil",
"Z.",
""
],
[
"Dusek",
"M.",
""
]
] |
quant-ph/9911072 | Jonathan A. Jones | H. K. Cummins and J. A. Jones | Use of composite rotations to correct systematic errors in NMR quantum
computation | 8 pages RevTex including 7 PostScript figures (18 subfigures) | New J. Phys. 2 6.1-6.12 (2000) | 10.1088/1367-2630/2/1/006 | JAJQP-99-03 | quant-ph | null | We implement an ensemble quantum counting algorithm on three NMR
spectrometers with 1H resonance frequencies of 500, 600 and 750 MHz. At higher
frequencies, the results deviate markedly from naive theoretical predictions.
These systematic errors can be attributed almost entirely to off-resonance
effects, which can be substantially corrected for using fully-compensating
composite rotation pulse sequences originally developed by Tycko. We also
derive an analytic expression for generating such sequences with arbitrary
rotation angles.
| [
{
"version": "v1",
"created": "Tue, 16 Nov 1999 15:38:56 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Cummins",
"H. K.",
""
],
[
"Jones",
"J. A.",
""
]
] |
quant-ph/9911073 | Dr. Arun Kumar Pati | Arun K. Pati | Existence of the Schmidt decomposition for tripartite systems | Latex prerpint style, 7 pages | null | 10.1016/S0375-9601(00)00767-2 | null | quant-ph | null | For any bipartite quantum system the Schmidt decomposition allows us to
express the state vector in terms of a single sum instead of double sums. We
show the existence of the Schmidt decomposition for tripartite system under
certain condition. If the partial inner product of a basis (belonging to a
Hilbert space of smaller dimension) with the state of the composite system
gives a disentangled basis, then the Schmidt decomposition for a tripartite
system exists. In this case the reduced density matrix of each of the subsystem
has equal spectrum in the Schmidt basis.
| [
{
"version": "v1",
"created": "Tue, 16 Nov 1999 19:14:38 GMT"
},
{
"version": "v2",
"created": "Tue, 11 Jul 2000 13:46:01 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Pati",
"Arun K.",
""
]
] |
quant-ph/9911074 | Alexander Y. Vlasov | Alexander Yu. Vlasov (FRC/IRH) | Error Correction with Euclidean Qubits | 13 pages \LaTeXe + amsmath, typo changes | Quantum Computers & Computing 2 (2001) 68 | null | null | quant-ph | null | In classical case there is simplest method of error correction with using
three equal bits instead of one. In the paper is shown, how the scheme fails
for quantum error correction with complex vector spaces of usual quantum
mechanics, but works in real and quaternionic cases. It is discussed also, how
to implement the three qubits scheme with using encoding of quaternionic qubit
by Majorana spinor. Necessary concepts and formulae from area of quantum error
corrections are closely introduced and proved.
| [
{
"version": "v1",
"created": "Tue, 16 Nov 1999 21:25:50 GMT"
},
{
"version": "v2",
"created": "Tue, 23 Nov 1999 19:56:06 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Vlasov",
"Alexander Yu.",
"",
"FRC/IRH"
]
] |
quant-ph/9911075 | Mikhail Sergeenko | M. N. Sergeenko | Semiclassical wave equation and exactness of the WKB method | 13 pages | Phys. Rev. A 53 (1996) 3798 | 10.1103/PhysRevA.53.3798 | null | quant-ph math-ph math.MP | null | The exactness of the semiclassical method for three-dimensional problems in
quantum mechanics is analyzed. The wave equation appropriate in the
quasiclassical region is derived. It is shown that application of the standard
leading-order WKB quantization condition to this equation reproduces exact
energy eigenvalues for all solvable spherically symmetric potentials.
| [
{
"version": "v1",
"created": "Tue, 16 Nov 1999 20:05:52 GMT"
}
] | 2012-07-02T00:00:00 | [
[
"Sergeenko",
"M. N.",
""
]
] |
quant-ph/9911076 | Stuart Mirell | Stuart Mirell, Daniel Mirell | High Efficiency Interaction-free Measurement from Continuous Wave
Multi-beam Interference | 7 pages, 2 figures | null | null | null | quant-ph | null | A new method for high efficiency interaction-free measurement is presented.
Selective transmission of multiple beam interference is used to generate a
continuous wave target beam with an irradiance level ~1% that of a reference
beam. When the target beam is unobstructed by a potentially interposed object,
the resultant measured interference visibility of 0.86 with the reference beam
significantly exceeds the classically predicted irradiance-based visibility of
0.17 and provides a methodology for ~100% interaction-free measurement with a
continuous wave beam.
| [
{
"version": "v1",
"created": "Tue, 16 Nov 1999 22:59:06 GMT"
},
{
"version": "v2",
"created": "Wed, 17 Nov 1999 04:27:17 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mirell",
"Stuart",
""
],
[
"Mirell",
"Daniel",
""
]
] |
quant-ph/9911077 | Sergei Kozyrev | L. Accardi, S.V. Kozyrev | The stochastic limit of quantum spin systems | 11 pages, LaTeX 2.09 | null | 10.1063/1.1291629 | Vlt-394 | quant-ph | null | The stochastic limit for the system of spins interacting with a boson field
is investigated. In the finite volume an application of the stochastic golden
rule shows that in the limit the dynamics of a quantum system is described by a
quantum white noise equation that after taking of normal order is equivalent to
quantum stochastic differential equation (QSDE). For the quantum Langevin
equation the dynamics is well defined and is a quantum flow on the infinite
lattice system.
| [
{
"version": "v1",
"created": "Wed, 17 Nov 1999 10:12:08 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Accardi",
"L.",
""
],
[
"Kozyrev",
"S. V.",
""
]
] |
quant-ph/9911078 | Accardi | L. Accardi, S. V. Kozyrev | On the structure of Markov flows | 22 pages, LaTeX 2.09, proof of Lemma 23 corrected | null | null | Vlt 393 | quant-ph | null | A new infinitesimal characterization of completely positive but not
necessarily homomorphic Markov flows from a C^*-algebra to bounded operators on
the boson Fock space over L^2(R) is given. Contrarily to previous
characterizations, based on stochastic differential equations, this
characterization is universal, i.e. valid for arbitrary Markov flows. With this
result the study of Markov flows is reduced to the study of four
C_0-semigroups. This includes the classical case and even in this case it seems
to be new. The result is applied to deduce a new existence theorem for Markov
flows.
| [
{
"version": "v1",
"created": "Wed, 17 Nov 1999 10:46:18 GMT"
},
{
"version": "v2",
"created": "Thu, 3 Feb 2000 12:25:45 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Accardi",
"L.",
""
],
[
"Kozyrev",
"S. V.",
""
]
] |
quant-ph/9911079 | C. King | C. King and M. B. Ruskai | Minimal Entropy of States Emerging from Noisy Quantum Channels | LATEX file; 44 pages, 7 figures; references added, typos corrected;
extended discussion of additivity for minimal entropy vs capacity | IEEE Trans. Info. Theory, 47, 192-209 (2001) | null | null | quant-ph | null | In this paper, we consider the minimal entropy of qubit states transmitted
through two uses of a noisy quantum channel, which is modeled by the action of
a completely positive trace-preserving (or stochastic) map. We provide strong
support for the conjecture that this minimal entropy is additive, namely that
the minimum entropy can be achieved when product states are transmitted.
Explicitly, we prove that for a tensor product of two unital stochastic maps on
qubit states, using an entanglement that involves only states which emerge with
minimal entropy cannot decrease the entropy below the minimum achievable using
product states. We give a separate argument, based on the geometry of the image
of the set of density matrices under stochastic maps, which suggests that the
minimal entropy conjecture holds for non-unital as well as for unital maps. We
also show that the maximal norm of the output states is multiplicative for most
product maps on $n$-qubit states, including all those for which at least one
map is unital.
For the class of {\it unital} channels on ${\bf C}^2$, we show that
additivity of minimal entropy implies that the Holevo capacity of the channel
is {\it additive} over two inputs, achievable with orthogonal states, and equal
to the Shannon capacity. This implies that superadditivity of the capacity is
possible only for non-unital channels.
| [
{
"version": "v1",
"created": "Wed, 17 Nov 1999 17:26:50 GMT"
},
{
"version": "v2",
"created": "Tue, 25 Jan 2000 23:23:02 GMT"
},
{
"version": "v3",
"created": "Wed, 2 Aug 2000 19:01:20 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"King",
"C.",
""
],
[
"Ruskai",
"M. B.",
""
]
] |
quant-ph/9911080 | Xuedong Hu | Xuedong Hu and S. Das Sarma | Hilbert space structure of a solid state quantum computer: two-electron
states of a double quantum dot artificial molecule | 22 2-column pages, 11 figures. Published version | Phys. Rev. A 61, 062301 (2000) | 10.1103/PhysRevA.61.062301 | null | quant-ph cond-mat.mes-hall | null | We study theoretically a double quantum dot hydrogen molecule in the GaAs
conduction band as the basic elementary gate for a quantum computer with the
electron spins in the dots serving as qubits. Such a two-dot system provides
the necessary two-qubit entanglement required for quantum computation. We
determine the excitation spectrum of two horizontally coupled quantum dots with
two confined electrons, and study its dependence on an external magnetic field.
In particular, we focus on the splitting of the lowest singlet and triplet
states, the double occupation probability of the lowest states, and the
relative energy scales of these states. We point out that at zero magnetic
field it is difficult to have both a vanishing double occupation probability
for a small error rate and a sizable exchange coupling for fast gating. On the
other hand, finite magnetic fields may provide finite exchange coupling for
quantum computer operations with small errors. We critically discuss the
applicability of the envelope function approach in the current scheme and also
the merits of various quantum chemical approaches in dealing with few-electron
problems in quantum dots, such as the Hartree-Fock self-consistent field
method, the molecular orbital method, the Heisenberg model, and the Hubbard
model. We also discuss a number of relevant issues in quantum dot quantum
computing in the context of our calculations, such as the required design
tolerance, spin decoherence, adiabatic transitions, magnetic field control, and
error correction.
| [
{
"version": "v1",
"created": "Wed, 17 Nov 1999 20:33:47 GMT"
},
{
"version": "v2",
"created": "Tue, 8 Feb 2000 00:05:10 GMT"
},
{
"version": "v3",
"created": "Tue, 16 May 2000 22:41:16 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Hu",
"Xuedong",
""
],
[
"Sarma",
"S. Das",
""
]
] |
quant-ph/9911081 | Mikhail Sergeenko | M. N. Sergeenko | Relativistic semiclassical wave equation and its solution | 12 pages, LaTex | Modern Physics Letters A Vol. 12, No. 37, pp. 2859-2871 (1997) | 10.1142/S0217732397002983 | null | quant-ph | null | The properties of relativistic particles in the quasiclassical region are
investigated. The relativistic semiclassical wave equation appropriate in the
quasiclassical region is derived. It is shown that the leading-order WKB
quantization rule is the appropriate method to solve the equation obtained.
| [
{
"version": "v1",
"created": "Thu, 18 Nov 1999 17:39:01 GMT"
}
] | 2016-02-17T00:00:00 | [
[
"Sergeenko",
"M. N.",
""
]
] |
quant-ph/9911082 | Ashish Ahuja | Ashish Ahuja, Sanjiv Kapoor | A Quantum Algorithm for finding the Maximum | TeX v3.2, 5 pages | null | null | null | quant-ph | null | This paper describes a quantum algorithm for finding the maximum among N
items. The classical method for the same problem takes O(N) steps because we
need to compare two numbers in one step. This algorithm takes O(sqrt(N)) steps
by exploiting the property of quantum states to exist in a superposition of
states and hence performing an operation on a number of elements in one go. A
tight upper bound of 6.8(sqrt(N)) for the number of steps needed using this
algorithm was found. These steps are the number of queries made to the oracle.
| [
{
"version": "v1",
"created": "Thu, 18 Nov 1999 08:39:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ahuja",
"Ashish",
""
],
[
"Kapoor",
"Sanjiv",
""
]
] |
quant-ph/9911083 | Nicola Manini | Nicola Manini and Fabio Pistolesi | Off-Diagonal Geometric Phases | 5 pages 2 figures - RevTeX. Revised version including geometrical
interpretation | Phys. Rev. Lett. 85, 3067 (2000) | 10.1103/PhysRevLett.85.3067 | null | quant-ph cond-mat | null | We investigate the adiabatic evolution of a set of non-degenerate eigenstates
of a parameterized Hamiltonian. Their relative phase change can be related to
geometric measurable quantities that extend the familiar concept of Berry phase
to the evolution of more than one state. We present several physical systems
where these concepts can be applied, including an experiment on microwave
cavities for which off-diagonal phases can be determined from published data.
| [
{
"version": "v1",
"created": "Thu, 18 Nov 1999 14:55:20 GMT"
},
{
"version": "v2",
"created": "Tue, 4 Jul 2000 14:57:05 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Manini",
"Nicola",
""
],
[
"Pistolesi",
"Fabio",
""
]
] |
quant-ph/9911084 | Thomas L. Cooper | Thomas L. Cooper | Dynamic Rules for Decoherence | 9 pages, 2 figures. [email protected] | null | null | null | quant-ph | null | In orthodox quantum theory, decoherence is presumed to be caused by
observation. In this paper, the idea of replacing observation, as the cause of
decoherence, with rules derived from the dynamics of the system is addressed.
Such rules determine the timing of decoherence and the states in the mixture
afterward. For instance, energy conservation during decohenence, for each
possible transition, leads to a timing rule. Exponetial decay and ergodic
behavior follow directly from the dynamic rules as do Boltzman's postulate of
equally probable micro-states and the Pauli rate equations. Ergodic behavior in
mesoscopic systems is predicted and those preditions are strikingly similar to
behavior observed in at least two laboratories.
| [
{
"version": "v1",
"created": "Thu, 18 Nov 1999 22:37:08 GMT"
},
{
"version": "v2",
"created": "Fri, 31 Dec 1999 22:29:41 GMT"
},
{
"version": "v3",
"created": "Tue, 1 Feb 2000 23:06:00 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Cooper",
"Thomas L.",
""
]
] |
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