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quant-ph/9807044 | null | Anna Okopi\'nska | Optimized perturbation method for the propagation in the anharmonic
oscillator potential | 13 pages, plain LATEX, 3 compressed and uuencoded Postscript figures,
submitted to Phys.Lett.A | Phys.Lett. A249 (1998) 259-264 | 10.1016/S0375-9601(98)00750-6 | null | quant-ph | null | The application of the optimized expansion for the quantum-mechanical
propagation in the anharmonic potential $\lambda x^4$ is discussed for real and
imaginary time. The first order results in the imaginary time formalism provide
approximations to the free energy and particle density which agree well with
the exact results in the whole range of temperatures.
| [
{
"version": "v1",
"created": "Fri, 17 Jul 1998 10:56:59 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Okopińska",
"Anna",
""
]
] |
quant-ph/9807045 | Ron S. Rubin | Ron Rubin and Nathan Salwen | A Canonical Quantization of the Baker's Map | 27 pages, 3 figures. Annals of Physics, to appear | Annals Phys. 269 (1998) 159-181 | 10.1006/aphy.1998.5845 | null | quant-ph | null | We present here a canonical quantization for the baker's map. The method we
use is quite different from that used in Balazs and Voros (ref.
\QCITE{cite}{}{BV}) and Saraceno (ref. \QCITE{cite}{}{S}). We first construct a
natural ``baker covering map'' on the plane $\QTO{mathbb}{\mathbb{R}}^{2}$. We
then use as the quantum algebra of observables the subalgebra of operators on
$L^{2}(\QTO{mathbb}{\mathbb{R}}) $ generated by $\left\{\exp (2\pi i\hat{x})
,\exp (2\pi i\hat{p}) \right\} $ . We construct a unitary propagator such that
as $\hbar \to 0$ the classical dynamics is returned. For Planck's constant
$h=1/N$, we show that the dynamics can be reduced to the dynamics on an
$N$-dimensional Hilbert space, and the unitary $N\times N$ matrix propagator is
the same as given in ref. \QCITE{cite}{}{BV} except for a small correction of
order $h$. This correction is shown to preserve the classical symmetry $x\to
1-x$ and $p\to 1-p$ in the quantum dynamics for periodic boundary conditions.
| [
{
"version": "v1",
"created": "Fri, 17 Jul 1998 15:34:44 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Rubin",
"Ron",
""
],
[
"Salwen",
"Nathan",
""
]
] |
quant-ph/9807046 | null | Bernd A. Berg | Relativistic Quantum Field Theory with a Physical State Vector | 10 pages revtex and 7 postscript figures. Minor inaccuracies about
cloning are corrected | null | null | null | quant-ph | null | Evolution of a physical quantum state vector is described as governed by two
distinct physical laws: Continuous, unitary time evolution and a
relativistically covariant reduction process. In previous literature, it was
concluded that a relativistically satisfactory version of the collapse
postulate is in contradiction with physical measurements of a non-local state
history. Here it is shown that such measurements are excluded when reduction is
formulated as a physical process and the measurement devices are included as
part of the state vector.
| [
{
"version": "v1",
"created": "Fri, 17 Jul 1998 20:53:16 GMT"
},
{
"version": "v2",
"created": "Mon, 31 Aug 1998 19:14:46 GMT"
}
] | 2009-09-25T00:00:00 | [
[
"Berg",
"Bernd A.",
""
]
] |
quant-ph/9807047 | Fabian Gaioli | Edgardo T. Garcia Alvarez and Fabian H. Gaioli | Exact derivation of the Langevin and master equations for harmonic
quantum Brownian motion | 7 pages, Revtex, to be published in Physica A | Physica A257:298-302,1998 | 10.1016/S0378-4371(98)00148-4 | null | quant-ph | null | A many particle Hamiltonian, where the interaction term conserves the number
of particles, is considered. A master equation for the populations of the
different levels is derived in an exact way. It results in a local equation
with time-dependent coefficients, which can be identified with the transition
probabilities in the golden rule approximation. A reinterpretation of the model
as a set of coupled harmonic oscillators enables one to obtain for one of them
an exact local Langevin equation, with time-dependent coefficients.
| [
{
"version": "v1",
"created": "Fri, 17 Jul 1998 22:25:54 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Alvarez",
"Edgardo T. Garcia",
""
],
[
"Gaioli",
"Fabian H.",
""
]
] |
quant-ph/9807048 | Fabian Gaioli | Fabian H. Gaioli, Edgardo T. Garcia Alvarez, and Mario A. Castagnino | The Gamow vectors and the Schwinger effect | 18 pages, Latex, Journal-Ref.: Int. J. Theor. Phys. 36, 2371-2389
(1997) | Int.J.Theor.Phys.36:2371-2389, 1997 | null | null | quant-ph hep-th | null | We introduce a `proper time' formalism to study the instability of the vacuum
in a uniform external electric field due to particle production. This formalism
allows us to reduce a quantum field theoretical problem to a quantum-mechanical
one in a higher dimension. The instability results from the inverted oscillator
structure which appears in the Hamiltonian. We show that the `proper time'
unitary evolution splits into two semigroups. The semigroup associated with
decaying Gamov vectors is related to the Feynman boundary conditions for the
Green functions and the semigroup associated with growing Gamov vectors is
related to the Dyson boundary conditions.
| [
{
"version": "v1",
"created": "Fri, 17 Jul 1998 22:27:29 GMT"
}
] | 2010-11-23T00:00:00 | [
[
"Gaioli",
"Fabian H.",
""
],
[
"Alvarez",
"Edgardo T. Garcia",
""
],
[
"Castagnino",
"Mario A.",
""
]
] |
quant-ph/9807049 | Fabian Gaioli | Fabian H. Gaioli, Edgardo T. Garcia Alvarez, and Diego G. Arbo | Quantum Brownian motion. II | 19 pages, Revtex, to be published in Int. J. Theor. Phys | Int.J.Theor.Phys. 38 (1999) 183-198 | null | null | quant-ph | null | This paper is devoted to generalize some previous results presented in Gaioli
et al., Int. J. Theor. Phys. 36, 2167 (1997). We evaluate the autocorrelation
function of the stochastic acceleration and study the asymptotic evolution of
the mean occupation number of a harmonic oscillator playing the role of a
Brownian particle. We also analyze some deviations from the Bose population at
low temperatures and compare it with the deviations from the exponential decay
law of an unstable quantum system.
| [
{
"version": "v1",
"created": "Fri, 17 Jul 1998 22:28:33 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gaioli",
"Fabian H.",
""
],
[
"Alvarez",
"Edgardo T. Garcia",
""
],
[
"Arbo",
"Diego G.",
""
]
] |
quant-ph/9807050 | Todd A. Brun | Todd A. Brun (ITP, UCSB), Ruediger Schack (Royal Holloway College,
London) | Realizing the quantum baker's map on an NMR quantum computer | Accepted by Phys. Rev. A. Numerous fairly minor revisions | Phys.Rev.A59:2649,1999 | 10.1103/PhysRevA.59.2649 | NSF-ITP-98-073 | quant-ph | null | By numerically simulating an implementation of the quantum baker's map on a
3-qubit NMR quantum computer based on the molecule trichloroethylene, we
demonstrate the feasibility of quantum chaos experiments on present-day quantum
computers. We give detailed descriptions of proposed experiments that
investigate (a) the rate of entropy increase due to decoherence and (b) the
phenomenon of hypersensitivity to perturbation.
| [
{
"version": "v1",
"created": "Sat, 18 Jul 1998 00:17:04 GMT"
},
{
"version": "v2",
"created": "Thu, 7 Jan 1999 20:00:47 GMT"
}
] | 2011-08-11T00:00:00 | [
[
"Brun",
"Todd A.",
"",
"ITP, UCSB"
],
[
"Schack",
"Ruediger",
"",
"Royal Holloway College,\n London"
]
] |
quant-ph/9807051 | Alexander Korotkov | Alexander N. Korotkov | Continuous quantum measurement with observer: pure wavefunction
evolution instead of decoherence | 6 pages, 2 figures | null | null | null | quant-ph cond-mat.mes-hall | null | We consider a continuous measurement of a two-level system (double-dot) by
weakly coupled detector (tunnel point contact nearby). While usual treatment
leads to the gradual system decoherence due to the measurement, we show that
the knowledge of the measurement result can restore the pure wavefunction at
any time (this can be experimentally verified). The formalism allows to write a
simple Langevin equation for the random evolution of the system density matrix
which is reflected and caused by the stochastic detector output. Gradual
wavefunction ``collapse'' and quantum Zeno effect are naturally described by
the equation.
| [
{
"version": "v1",
"created": "Sat, 18 Jul 1998 20:03:24 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Korotkov",
"Alexander N.",
""
]
] |
quant-ph/9807052 | Dan Ventura | Dan Ventura and Tony Martinez | A Quantum Computational Learning Algorithm | This is a reworked and improved version of a paper originally
entitled "Quantum Harmonic Sieve: Learning DNF Using a Classical Example
Oracle" | null | null | null | quant-ph | null | An interesting classical result due to Jackson allows polynomial-time
learning of the function class DNF using membership queries. Since in most
practical learning situations access to a membership oracle is unrealistic,
this paper explores the possibility that quantum computation might allow a
learning algorithm for DNF that relies only on example queries. A natural
extension of Fourier-based learning into the quantum domain is presented. The
algorithm requires only an example oracle, and it runs in O(sqrt(2^n)) time, a
result that appears to be classically impossible. The algorithm is unique among
quantum algorithms in that it does not assume a priori knowledge of a function
and does not operate on a superposition that includes all possible states.
| [
{
"version": "v1",
"created": "Sat, 18 Jul 1998 22:52:48 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ventura",
"Dan",
""
],
[
"Martinez",
"Tony",
""
]
] |
quant-ph/9807053 | Dan Ventura | Dan Ventura and Tony Martinez | Quantum Associative Memory | null | null | null | null | quant-ph | null | This paper combines quantum computation with classical neural network theory
to produce a quantum computational learning algorithm. Quantum computation uses
microscopic quantum level effects to perform computational tasks and has
produced results that in some cases are exponentially faster than their
classical counterparts. The unique characteristics of quantum theory may also
be used to create a quantum associative memory with a capacity exponential in
the number of neurons. This paper combines two quantum computational algorithms
to produce such a quantum associative memory. The result is an exponential
increase in the capacity of the memory when compared to traditional associative
memories such as the Hopfield network. The paper covers necessary high-level
quantum mechanical and quantum computational ideas and introduces a quantum
associative memory. Theoretical analysis proves the utility of the memory, and
it is noted that a small version should be physically realizable in the near
future.
| [
{
"version": "v1",
"created": "Sat, 18 Jul 1998 23:00:18 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ventura",
"Dan",
""
],
[
"Martinez",
"Tony",
""
]
] |
quant-ph/9807054 | Dan Ventura | Dan Ventura and Tony Martinez | Initializing the Amplitude Distribution of a Quantum State | null | Found.Phys.Lett. 12 (1999) 547-559 | null | null | quant-ph | null | To date, quantum computational algorithms have operated on a superposition of
all basis states of a quantum system. Typically, this is because it is assumed
that some function f is known and implementable as a unitary evolution.
However, what if only some points of the function f are known? It then becomes
important to be able to encode only the knowledge that we have about f. This
paper presents an algorithm that requires a polynomial number of elementary
operations for initializing a quantum system to represent only the m known
points of a function f.
| [
{
"version": "v1",
"created": "Sat, 18 Jul 1998 23:03:41 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ventura",
"Dan",
""
],
[
"Martinez",
"Tony",
""
]
] |
quant-ph/9807055 | N. David Mermin | N. David Mermin | What Do These Correlations Know About Reality? Nonlocality and the
Absurd | 15 pages, no figures, plain TEX | Found.Phys. 29 (1999) 571-587 | null | null | quant-ph | null | In honor of Daniel Greenberger's 65th birthday I record for posterity two
superb examples of his wit, offer a proof of an important theorem on quantum
correlations that even those of us over 60 can understand, and suggest, by
trying to make it look silly, that invoking ``quantum nonlocality'' as an
explanation for such correlations may be too cheap a way out of the dilemma
they pose.
| [
{
"version": "v1",
"created": "Mon, 20 Jul 1998 21:27:38 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Mermin",
"N. David",
""
]
] |
quant-ph/9807056 | Ron S. Rubin | Ron Rubin and Andrew Lesniewski | Quantum Mechanics on a Torus | 27 pages, 2 figures | null | null | null | quant-ph | null | We present here a canonical description for quantizing classical maps on a
torus. We prove theorems analagous to classical theorems on mixing and
ergodicity in terms of a quantum Koopman space $ L^2 (A_\hbar},\tau_\hbar) $
obtained as the completion of the algebra of observables $ A_\hbar $ in the
norm induced by the following inner product $(A,B) =\tau_{\hbar}(A^{\dagger}B)
$, where $\tau_{\hbar}$ is a linear functional on the algebra analogous to the
classical ``integral over phase space.'' We also derive explicit formulas
connecting this formulation to the $\theta $-torus decomposition of Bargmann
space introduced in ref. \QCITE{cite}{}{KLMR}.
| [
{
"version": "v1",
"created": "Mon, 20 Jul 1998 22:13:11 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rubin",
"Ron",
""
],
[
"Lesniewski",
"Andrew",
""
]
] |
quant-ph/9807057 | Haiqing Wei | Haiqing Wei and Xin Xue | Single Molecule Magnetic Resonance and Quantum Computation | null | null | null | null | quant-ph | null | It is proposed that nuclear (or electron) spins in a trapped molecule would
be well isolated from the environment and the state of each spin can be
measured by means of mechanical detection of magnetic resonance. Therefore
molecular traps make an entirely new approach possible for spin-resonance
quantum computation which can be conveniently scaled up. In the context of
magnetic resonance spectroscopy, a molecular trap promises the ultimate
sensitivity for single spin detection and an unprecedented spectral resolution
as well.
| [
{
"version": "v1",
"created": "Tue, 21 Jul 1998 01:51:54 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Nov 1998 02:50:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Wei",
"Haiqing",
""
],
[
"Xue",
"Xin",
""
]
] |
quant-ph/9807058 | Jonathan Oppenheim | J. Oppenheim, B. Reznik, W.G. Unruh | Time as an Observable | To be published in Proceedings of the 10th Max Born Symposium, eds.
Ph. Blanchard, A. Jadczyk, Wroclaw - Sept., 1997, Springer-Verlag, Lecture
Notes in Physics | null | 10.1007/BFb0105347 | null | quant-ph gr-qc | null | The role of time in quantum mechanics is discussed. The differences between
ordinary observables and an observable which corresponds to the time of an
event is examined. In particular, the time-of-arrival of a particle to a fixed
location is not an ordinary quantum mechanical observable. While we can measure
if the particle arrives, we argue that the time at which it arrives always has
an inherent ambiguity. The minimum inaccuracy of time-of-arrival measurements
is given by dt>1/E where E is the kinetic energy of the particle. The use of
time-of-arrival operators, as well as current operators, is examined
critically.
| [
{
"version": "v1",
"created": "Tue, 21 Jul 1998 02:55:15 GMT"
},
{
"version": "v2",
"created": "Fri, 7 Aug 1998 23:28:43 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Oppenheim",
"J.",
""
],
[
"Reznik",
"B.",
""
],
[
"Unruh",
"W. G.",
""
]
] |
quant-ph/9807059 | Marco Toller | M. Toller (Department of physics of the University, I. N. F. N.
Trento, Italy.) | Variance of the Quantum Coordinates of an Event | 16 pages, latex, no figures | Int.J.Theor.Phys. 38 (1999) 2015-2028 | null | null | quant-ph astro-ph gr-qc | null | We study the variances of the coordinates of an event considered as quantum
observables in a Poincare' covariant theory. The starting point is their
description in terms of a covariant positive-operator-valued measure on the
Minkowski space-time. Besides the usual uncertainty relations, we find
stronger inequalities involving the mass and the centre-of-mass angular
momentum of the object that defines the event. We suggest that these
inequalities may help to clarify some of the arguments which have been given in
favour of a gravitational quantum limit to the accuracy of time and space
measurements.
| [
{
"version": "v1",
"created": "Tue, 21 Jul 1998 06:50:53 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Toller",
"M.",
"",
"Department of physics of the University, I. N. F. N.\n Trento, Italy."
]
] |
quant-ph/9807060 | Esposito Giampiero | Giampiero Esposito | Complex Parameters in Quantum Mechanics | 17 pages, plain Tex. The revised version is much longer, and section
5 is entirely new | Found.Phys.Lett. 11 (1998) 535-547 | null | DSF preprint 98/26 | quant-ph | null | The Schrodinger equation for stationary states in a central potential is
studied in an arbitrary number of spatial dimensions, say q. After
transformation into an equivalent equation, where the coefficient of the first
derivative vanishes, it is shown that in such equation the coefficient of the
second inverse power of r is an even function of a parameter, say lambda,
depending on a linear combination of q and of the angular momentum quantum
number, say l. Thus, the case of complex values of lambda, which is useful in
scattering theory, involves, in general, both a complex value of the parameter
originally viewed as the spatial dimension and complex values of the angular
momentum quantum number. The paper ends with a proof of the Levinson theorem in
an arbitrary number of spatial dimensions, when the potential includes a
non-local term which might be useful to understand the interaction between two
nucleons.
| [
{
"version": "v1",
"created": "Tue, 21 Jul 1998 08:44:57 GMT"
},
{
"version": "v2",
"created": "Wed, 4 Nov 1998 16:44:07 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Esposito",
"Giampiero",
""
]
] |
quant-ph/9807061 | Fabian Gaioli | Fabian H. Gaioli and Edgardo T. Garcia Alvarez | Exact time evolution in harmonic quantum Brownian motion | 7 pages, 4 figures, Revtex, submitted to Physica A | Physica A264:338-344,1999 | 10.1016/S0378-4371(98)00456-7 | null | quant-ph | null | We consider a particular (exactly soluble) model of the one discussed in a
previous work. We show numerical results for the time evolution of the main
dynamical quantities and compare them with analytical results.
| [
{
"version": "v1",
"created": "Tue, 21 Jul 1998 23:31:46 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Gaioli",
"Fabian H.",
""
],
[
"Alvarez",
"Edgardo T. Garcia",
""
]
] |
quant-ph/9807062 | Fabian Gaioli | Fabian H. Gaioli, Edgardo T. Garcia Alvarez, and Javier Guevara | Quantum Brownian motion | 40 pages, 29 figures, Revtex | Int.J.Theor.Phys. 36 (1997) 2167-2207 | null | null | quant-ph | null | We study the behavior of a subsystem (harmonic oscillator) in contact with a
thermal reservoir (finite set of uncoupled harmonic oscillators). We exactly
solve the eigenvalue problem and obtain the temporal evolution of the dynamical
variables of interest. We show how the subsystem goes to equilibrium and give
quantitative estimates of the Poincar\'e recurrence times. We study the
behavior of the subsystem mean ocuppation number in the limit of a dense bath
and compare it with the expected exponential decay law.
| [
{
"version": "v1",
"created": "Tue, 21 Jul 1998 23:37:35 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gaioli",
"Fabian H.",
""
],
[
"Alvarez",
"Edgardo T. Garcia",
""
],
[
"Guevara",
"Javier",
""
]
] |
quant-ph/9807063 | Jurgen Brendel | H. Gisin, J. Brendel, H. Zbinden, A. Sergienko, A. Muller | Twin-photon techniques for fiber measurements | 6 pages, 5 figures, Invited paper for the Symposium on Optical Fiber
Measurements, sponsored by NIST, Boulder, Co, September 15-17, 1998 | null | null | GAP-98-ME02 | quant-ph | null | The potential of twin photons generated by parametric down-conversion for
metrological applications are discussed. We present several experimental
results like the measurement of chromatic dispersion and polarization mode
dispersion in optical fibers.
| [
{
"version": "v1",
"created": "Wed, 22 Jul 1998 14:42:32 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gisin",
"H.",
""
],
[
"Brendel",
"J.",
""
],
[
"Zbinden",
"H.",
""
],
[
"Sergienko",
"A.",
""
],
[
"Muller",
"A.",
""
]
] |
quant-ph/9807064 | Martin Roetteler | Markus Pueschel, Martin Roetteler, and Thomas Beth (Universitaet
Karlsruhe) | Fast Quantum Fourier Transforms for a Class of Non-abelian Groups | 16 pages, LaTeX2e | Proceedings 13th International Symposium on Applied Algebra,
Algebraic Algorithms and Error-Correcting Codes (AAECC'99), Honolulu, Hawaii,
Springer LNCS, pp. 148-159, 1999 | null | null | quant-ph cs.ET | null | An algorithm is presented allowing the construction of fast Fourier
transforms for any solvable group on a classical computer. The special
structure of the recursion formula being the core of this algorithm makes it a
good starting point to obtain systematically fast Fourier transforms for
solvable groups on a quantum computer. The inherent structure of the Hilbert
space imposed by the qubit architecture suggests to consider groups of order
2^n first (where n is the number of qubits). As an example, fast quantum
Fourier transforms for all 4 classes of non-abelian 2-groups with cyclic normal
subgroup of index 2 are explicitly constructed in terms of quantum circuits.
The (quantum) complexity of the Fourier transform for these groups of size 2^n
is O(n^2) in all cases.
| [
{
"version": "v1",
"created": "Wed, 22 Jul 1998 21:25:34 GMT"
}
] | 2023-11-27T00:00:00 | [
[
"Pueschel",
"Markus",
"",
"Universitaet\n Karlsruhe"
],
[
"Roetteler",
"Martin",
"",
"Universitaet\n Karlsruhe"
],
[
"Beth",
"Thomas",
"",
"Universitaet\n Karlsruhe"
]
] |
quant-ph/9807065 | Peter Muller | Werner Fischer, Hajo Leschke, Peter Mueller | On the averaged quantum dynamics by white-noise Hamiltonians with and
without dissipation | 44 pages | Annalen Phys. 7 (1998) 59-100 | 10.1002/andp.2090070203 | null | quant-ph cond-mat.stat-mech | null | Exact results are derived on the averaged dynamics of a class of random
quantum-dynamical systems in continuous space. Each member of the class is
characterized by a Hamiltonian which is the sum of two parts. While one part is
deterministic, time-independent and quadratic, the Weyl-Wigner symbol of the
other part is a homogeneous Gaussian random field which is delta correlated in
time, but smoothly correlated in position and momentum. The averaged dynamics
of the resulting white-noise system is shown to be a monotone mixing increasing
quantum-dynamical semigroup. Its generator is computed explicitly. Typically,
in the course of time the mean energy of such a system grows linearly to
infinity. In the second part of the paper an extended model is studied, which,
in addition, accounts for dissipation by coupling the white-noise system
linearly to a quantum-mechanical harmonic heat bath. It is demonstrated that,
under suitable assumptions on the spectral density of the heat bath, the mean
energy then saturates for long times.
| [
{
"version": "v1",
"created": "Thu, 23 Jul 1998 14:57:24 GMT"
}
] | 2016-10-26T00:00:00 | [
[
"Fischer",
"Werner",
""
],
[
"Leschke",
"Hajo",
""
],
[
"Mueller",
"Peter",
""
]
] |
quant-ph/9807066 | null | J. G. Muga, C. R. Leavens and J. P. Palao | Space-time properties of free motion time-of-arrival eigenstates | REVTEX, 12 pages, 4 postscript figures | Phys.Rev. A58 (1998) 1 | 10.1103/PhysRevA.58.4336 | ULL-FIS-980701 | quant-ph | null | The properties of the time-of-arrival operator for free motion introduced by
Aharonov and Bohm and of its self-adjoint variants are studied. The domains of
applicability of the different approaches are clarified. It is shown that the
arrival time of the eigenstates is not sharply defined. However, strongly
peaked real-space (normalized) wave packets constructed with narrow Gaussian
envelopes centred on one of the eigenstates provide an arbitrarily sharp
arrival time.
| [
{
"version": "v1",
"created": "Thu, 23 Jul 1998 22:51:35 GMT"
}
] | 2019-08-17T00:00:00 | [
[
"Muga",
"J. G.",
""
],
[
"Leavens",
"C. R.",
""
],
[
"Palao",
"J. P.",
""
]
] |
quant-ph/9807067 | Dr. A. K. Pati | Arun Kumar Pati (Theory Div. BARC, Mumbai, India) | Fast quantum search algorithm and Bounds on it | Latex file, Two column, 4 pages, no figures | null | null | null | quant-ph | null | We recast Grover's generalised search algorithm in a geometric language even
when the states are not approximately orthogonal. We provide a possible search
algorithm based on an arbitrary unitary transformation which can speed up the
steps still further. We discuss the lower and upper bounds on the transition
matrix elements when the unitary operator changes with time, thereby implying
that quantum search process can not be too fast or too slow. This is a
remarkable feature of quantum computation unlike classical one. Quantum
mechanical uncertainty relation puts bounds on search process. Also we mention
the problems of perturbation and other issues in time-dependent search
operation.
| [
{
"version": "v1",
"created": "Fri, 24 Jul 1998 07:41:19 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Pati",
"Arun Kumar",
"",
"Theory Div. BARC, Mumbai, India"
]
] |
quant-ph/9807068 | Hagen Kleinert | H. Kleinert, D.H. Lin | Relativistic Trace Formula for Bound States in Terms of Classical
Periodic Orbits | Author Information under
http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of
paper also at http://www.physik.fu-berlin.de/~kleinert/kleiner_re272 | null | null | null | quant-ph | null | We set up a trace formula for the relativistic density of states in terms of
a topological sum of classical periodic orbits. The result is applicable to any
relativistic integrable system.
| [
{
"version": "v1",
"created": "Fri, 24 Jul 1998 08:51:09 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kleinert",
"H.",
""
],
[
"Lin",
"D. H.",
""
]
] |
quant-ph/9807069 | N. Linden | N Linden and S Popescu | Bound Entanglement and Teleportation | 3 pages, RevTeX | null | 10.1103/PhysRevA.59.137 | null | quant-ph | null | Recently M. Horodecki, P. Horodecki and R. Horodecki have introduced a set of
density matrices of two spin-1 particles from which it is not possible to
distill any maximally entangled states, even though the density matrices are
entangled. Thus these density matrices do not allow reliable teleportation.
However it might nevertheless be the case that these states can be used for
teleportation, not reliably, but still with fidelity greater than that which
may be achieved with a classical scheme. We show that, at least for some of
these density matrices, teleportation cannot be achieved with better than
classical fidelity.
| [
{
"version": "v1",
"created": "Fri, 24 Jul 1998 16:48:44 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Linden",
"N",
""
],
[
"Popescu",
"S",
""
]
] |
quant-ph/9807070 | Daniel S. Abrams | Daniel S. Abrams and Seth Lloyd | A quantum algorithm providing exponential speed increase for finding
eigenvalues and eigenvectors | 10 pages | Phys.Rev.Lett.83:5162-5165,1999 | 10.1103/PhysRevLett.83.5162 | null | quant-ph | null | We describe a new polynomial time quantum algorithm that uses the quantum
fast fourier transform to find eigenvalues and eigenvectors of a Hamiltonian
operator, and that can be applied in cases (commonly found in ab initio physics
and chemistry problems) for which all known classical algorithms require
exponential time. Applications of the algorithm to specific problems are
considered, and we find that classically intractable and interesting problems
from atomic physics may be solved with between 50 and 100 quantum bits.
| [
{
"version": "v1",
"created": "Fri, 24 Jul 1998 18:10:24 GMT"
}
] | 2009-01-23T00:00:00 | [
[
"Abrams",
"Daniel S.",
""
],
[
"Lloyd",
"Seth",
""
]
] |
quant-ph/9807071 | Daniel F. V. James | D. F. V. James, M. S. Gulley, M. H. Holzscheiter, R. J. Hughes, P. G.
Kwiat, S. K. Lamoreaux, C. G. Peterson, V. D. Sandberg, M. M. Schauer, C. M.
Simmons, D. Tupa, P. Z. Wang, A. G. White (Los Alamos National Laboratory) | Trapped Ion Quantum Computer Research at Los Alamos | 12 pages, 6 figures; to appear in Proc. NASA-QCQC'98 | Lecture Notes in Computer Science 1509, 426-437 (1999) | null | LA-UR 98-314 | quant-ph | null | We briefly review the development and theory of an experiment to investigate
quantum computation with trapped calcium ions. The ion trap, laser and ion
requirements are determined, and the parameters required for simple quantum
logic operations are described
| [
{
"version": "v1",
"created": "Fri, 24 Jul 1998 19:27:21 GMT"
}
] | 2008-01-13T00:00:00 | [
[
"James",
"D. F. V.",
"",
"Los Alamos National Laboratory"
],
[
"Gulley",
"M. S.",
"",
"Los Alamos National Laboratory"
],
[
"Holzscheiter",
"M. H.",
"",
"Los Alamos National Laboratory"
],
[
"Hughes",
"R. J.",
"",
"Los Alamos National Laboratory"
],
[
"Kwiat",
"P. G.",
"",
"Los Alamos National Laboratory"
],
[
"Lamoreaux",
"S. K.",
"",
"Los Alamos National Laboratory"
],
[
"Peterson",
"C. G.",
"",
"Los Alamos National Laboratory"
],
[
"Sandberg",
"V. D.",
"",
"Los Alamos National Laboratory"
],
[
"Schauer",
"M. M.",
"",
"Los Alamos National Laboratory"
],
[
"Simmons",
"C. M.",
"",
"Los Alamos National Laboratory"
],
[
"Tupa",
"D.",
"",
"Los Alamos National Laboratory"
],
[
"Wang",
"P. Z.",
"",
"Los Alamos National Laboratory"
],
[
"White",
"A. G.",
"",
"Los Alamos National Laboratory"
]
] |
quant-ph/9807072 | Guo Guangcan | Lu-Ming Duan and Guang-Can Guo (University of Science and Technology
of China) | Pulse controlled noise suppressed quantum computation | 12 pages, latex | null | null | null | quant-ph | null | To make arbitrarily accurate quantum computation possible, practical
realization of quantum computers will require suppressing noise in quantum
memory and gate operations to make it below a threshold value. A scheme based
on realistic quantum computer models is described for suppressing noise in
quantum computation without the cost of stringent quantum computing resources.
| [
{
"version": "v1",
"created": "Sun, 26 Jul 1998 10:23:48 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Duan",
"Lu-Ming",
"",
"University of Science and Technology\n of China"
],
[
"Guo",
"Guang-Can",
"",
"University of Science and Technology\n of China"
]
] |
quant-ph/9807073 | Hagen Kleinert | Hagen Kleinert | Solution of Coulomb Path Integral in Momentum Space | Author Information under
http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of
paper also at http://www.physik.fu-berlin.de/~kleinert/kleiner_re/273 | Phys.Lett. A252 (1999) 277-280 | 10.1016/S0375-9601(99)00018-3 | null | quant-ph | null | The path integral for a point particle in a Coulomb potential is solved in
momentum space. The solution permits us to give for the first time a negative
answer to an old question of quantum mechanics in curved spaces raised in 1957
by DeWitt, whether the Hamiltonian of a particle in a curved space contains an
additional term proportional to the curvature scalar $R$. We show that this
would cause experimentally wrong level spacings in the hydrogen atom. Our
solution also gives a first experimental confirmation of the correctness of the
measure of integration in path integrals in curved space implied by a recently
discovered nonholonomic mapping principle.
| [
{
"version": "v1",
"created": "Mon, 27 Jul 1998 09:10:40 GMT"
},
{
"version": "v2",
"created": "Tue, 2 Feb 1999 14:29:35 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Kleinert",
"Hagen",
""
]
] |
quant-ph/9807074 | Chiara Macchiavello | Chiara Macchiavello (university of Pavia) | On the analytical convergence of the QPA procedure | 3 pages (revtex), 1 figure, to appear in Phys. Lett. A | Phys.Lett. A246 (1998) 385-388 | 10.1016/S0375-9601(98)00550-7 | null | quant-ph | null | We present an analytical proof of the convergence of the ``quantum privacy
amplification'' procedure proposed by D. Deutsch et al. [Phys. Rev. Lett. 77,
2818 (1996)]. The proof specifies the range of states which can be purified by
this method.
| [
{
"version": "v1",
"created": "Mon, 27 Jul 1998 10:44:35 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Macchiavello",
"Chiara",
"",
"university of Pavia"
]
] |
quant-ph/9807075 | Lev Vaidman | L. Vaidman | Time-Symmetrized Counterfactuals in Quantum Theory | This is a preprint from July 97 and it has partial overlap with
quant-ph/9609007 and quant-ph/9802042. It is submitted now, in part because
the paper (accepted for publication) by R. Kastner, quant-ph/9806002
addresses this manuscript | Found.Phys. 29 (1999) 755-765 | null | TAUP 2459-97 | quant-ph | null | Recently, several authors have criticized the time-symmetrized quantum theory
originated by the work of Aharonov et al. (1964). The core of this criticism
was a proof, appearing in various forms, which showed that the counterfactual
interpretation of time-symmetrized quantum theory cannot be reconciled with
standard quantum theory. I argue here that the apparent contradiction is due to
a logical error. I analyze the concept of counterfactuals in quantum theory and
introduce time-symmetrized counterfactuals. These counterfactuals do not lead
to any contradiction with the predictions of quantum theory. I discuss
applications of time-symmetrized counterfactuals to several surprising examples
and show the usefulness of the time-symmetrized quantum formalism.
| [
{
"version": "v1",
"created": "Mon, 27 Jul 1998 13:15:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Vaidman",
"L.",
""
]
] |
quant-ph/9807076 | George B. Cvijanovich | George B. Cvijanovich | Epistemology of Quantization | 10 pages and no figures | null | null | null | quant-ph | null | A notion of quantization is proposed that is independent of the original
statistical interpretation of the distribution of energy in a photon gas or of
the quantization of angular momentum in hydrogen atom. Such a procedutre
implies the existance of finite space-time four-interval that any relativistic
preparation and measurement of a physical event requires. That finite
four-interval is also the epistemological source of QM uncertainty relations.
Furthermore, the consetrvation of helicity in the propagation of a photon is a
relativistic invariant, and is the origin of the "appearence" of a paradox of
nonlocal interaction in Bell's inequality [2,3,4] as shown in A. Aspect et all
[5] experiment. That is a spin of a photon is always correlated with its
momentum.
| [
{
"version": "v1",
"created": "Mon, 27 Jul 1998 17:06:48 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Cvijanovich",
"George B.",
""
]
] |
quant-ph/9807077 | Guifre Vidal Bonafont | Guifre Vidal | Entanglement monotones | Revtex, 13 pages, no figures. Previous title: "On the
characterization of entanglement". Major changes in notation and structure.
Some new results, comments and references have been added | J.Mod.Opt. 47 (2000) 355 | 10.1080/09500340008244048 | null | quant-ph | null | In the context of quantifying entanglement we study those functions of a
multipartite state which do not increase under the set of local
transformations. A mathematical characterization of these monotone magnitudes
is presented. They are then related to optimal strategies of conversion of
shared states. More detailed results are presented for pure states of bipartite
systems. It is show that more than one measure are required simultaneously in
order to quantify completely the non-local resources contained in a bipartite
pure state, while examining how this fact does not hold in the so-called
asymptotic limit. Finally, monotonicity under local transformations is proposed
as the only natural requirement for measures of entanglement.
| [
{
"version": "v1",
"created": "Tue, 28 Jul 1998 09:33:51 GMT"
},
{
"version": "v2",
"created": "Thu, 25 Mar 1999 10:52:06 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Vidal",
"Guifre",
""
]
] |
quant-ph/9807078 | Douglas Ross | D.A. Ross | A Modification of Grover's Algorithm as a Fast Database Search | 7 pages | null | null | null | quant-ph | null | A modification of Grover's algorithm is proposed, which can be used directly
as a fast database search. An explicit two q-bit example is displayed in
detail. We discuss the case where the database has multiple entries
corresponding to the same target value.
| [
{
"version": "v1",
"created": "Tue, 28 Jul 1998 09:54:54 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ross",
"D. A.",
""
]
] |
quant-ph/9807079 | B. Kappler | Heinz-Peter Breuer, Bernd Kappler and Francesco Petruccione | Stochastic wave function approach to the calculation of multitime
correlation functions of open quantum systems | RevTex, 19 pages, 3 figures, uses multicol | Phys.Rev. A56 (1997) 2334-2351 | 10.1103/PhysRevA.56.2334 | null | quant-ph | null | Within the framework of probability distributions on projective Hilbert space
a scheme for the calculation of multitime correlation functions is developed.
The starting point is the Markovian stochastic wave function description of an
open quantum system coupled to an environment consisting of an ensemble of
harmonic oscillators in arbitrary pure or mixed states. It is shown that matrix
elements of reduced Heisenberg picture operators and general time-ordered
correlation functions can be expressed by time-symmetric expectation values of
extended operators in a doubled Hilbert space. This representation allows the
construction of a stochastic process in the doubled Hilbert space which enables
the determination of arbitrary matrix elements and correlation functions. The
numerical efficiency of the resulting stochastic simulation algorithm is
investigated and compared with an alternative Monte Carlo wave function method
proposed first by Dalibard et al. [Phys. Rev. Lett. {\bf 68}, 580 (1992)]. By
means of a standard example the suggested algorithm is shown to be more
efficient numerically and to converge faster. Finally, some specific examples
from quantum optics are presented in order to illustrate the proposed method,
such as the coupling of a system to a vacuum, a squeezed vacuum within a finite
solid angle, and a thermal mixture of coherent states.
| [
{
"version": "v1",
"created": "Tue, 28 Jul 1998 11:11:54 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Breuer",
"Heinz-Peter",
""
],
[
"Kappler",
"Bernd",
""
],
[
"Petruccione",
"Francesco",
""
]
] |
quant-ph/9807080 | B. Kappler | H. P. Breuer, B. Kappler and F. Petruccione | Heisenberg picture operators in the stochastic wave function approach to
open quantum systems | RevTex, 5 pages, 2 figures, uses multicol | Eur.Phys.J. D1 (1998) 9-13 | 10.1007/s100530050058 | null | quant-ph | null | A fast simulation algorithm for the calculation of multitime correlation
functions of open quantum systems is presented. It is demonstrated that any
stochastic process which ``unravels'' the quantum Master equation can be used
for the calculation of matrix elements of reduced Heisenberg picture operators,
and thus for the calculation of multitime correlation functions, by extending
the stochastic process to a doubled Hilbert space. The numerical performance of
the stochastic simulation algorithm is investigated by means of a standard
example.
| [
{
"version": "v1",
"created": "Tue, 28 Jul 1998 11:22:52 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Breuer",
"H. P.",
""
],
[
"Kappler",
"B.",
""
],
[
"Petruccione",
"F.",
""
]
] |
quant-ph/9807081 | Georg Junker | Georg Junker, Pinaki Roy | Non-linear coherent states associated with conditionally exactly
solvable problems | 10 pages, 2 figures, uses IOP macros | Phys.Lett. A257 (1999) 113-119 | 10.1016/S0375-9601(99)00317-5 | null | quant-ph | null | Recently, based on a supersymmetric approach, new classes of conditionally
exactly solvable problems have been found, which exhibit a symmetry structure
characterized by non-linear algebras. In this paper the associated
``non-linear'' coherent states are constructed and some of their properties are
discussed in detail.
| [
{
"version": "v1",
"created": "Wed, 29 Jul 1998 07:21:04 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Junker",
"Georg",
""
],
[
"Roy",
"Pinaki",
""
]
] |
quant-ph/9807082 | B. Kappler | Heinz-Peter Breuer, Bernd Kappler, and Francesco Petruccione | Heisenberg picture operators in the quantum state diffusion model | LaTeX2E, 6 pages, 3 figures, uses iopart | J.Phys. A31 (1998) L147-L151 | 10.1088/0305-4470/31/7/002 | null | quant-ph | null | A stochastic simulation algorithm for the computation of multitime
correlation functions which is based on the quantum state diffusion model of
open systems is developed. The crucial point of the proposed scheme is a
suitable extension of the quantum master equation to a doubled Hilbert space
which is then unraveled by a stochastic differential equation.
| [
{
"version": "v1",
"created": "Wed, 29 Jul 1998 08:46:24 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Breuer",
"Heinz-Peter",
""
],
[
"Kappler",
"Bernd",
""
],
[
"Petruccione",
"Francesco",
""
]
] |
quant-ph/9807083 | Taksu Cheon de Caracorum | T. Shigehara, M. Yokoyama, H. Mizoguchi, T. Mishima (Saitama U) and
Taksu Cheon (Kochi Tech) | Influence of Small Impurities on Low-Energy Electron Dynamics in
Two-Dimensional Microscopic Bounded Region | LaTeX 5 Pages, Talk presented at The 1998 International technical
Conference on Circuits/Systems, Computers and Communications (ITC-CSCC'98),
Sokcho, Korea, July 13-15, 1998 | null | null | null | quant-ph chao-dyn cond-mat nlin.CD nucl-th | null | In order to give some insight into a role of small impurities on the electron
motion in microscopic devices, we examine from a general viewpoint, the effect
of small obstacles on a particle motion at low energy inside microscopic
bounded regions. It will be shown that the obstacles disturb the electron
motion only if they are weakly attractive.
| [
{
"version": "v1",
"created": "Wed, 29 Jul 1998 16:38:51 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Shigehara",
"T.",
"",
"Saitama U"
],
[
"Yokoyama",
"M.",
"",
"Saitama U"
],
[
"Mizoguchi",
"H.",
"",
"Saitama U"
],
[
"Mishima",
"T.",
"",
"Saitama U"
],
[
"Cheon",
"Taksu",
"",
"Kochi Tech"
]
] |
quant-ph/9807084 | Jose Luis Sanchez Gomez | R.F. Alvarez-Estrada and J.L. Sanchez-Gomez | On the Absence of the Zeno Effect in Relativistic Quantum Field Theory | Revised version of the paper Time evolution and Zeno effect in
relativistic quantum field theory. To appear in Phys. Lett. A | null | 10.1016/S0375-9601(99)00084-5 | null | quant-ph | null | We study the time evolution of decaying particles in renormalizable models of
Relativistic Quantum Field Theory. Significant differences between the latter
and Non Relativistic Quantum Mechanics are found -in particular, the Zeno
effect seems to be absent in such RQFT models. Conventional renormalization
yields finite time behavior in some cases but fails to produce finite survival
probabilities in others.
| [
{
"version": "v1",
"created": "Wed, 29 Jul 1998 16:50:01 GMT"
},
{
"version": "v2",
"created": "Fri, 5 Feb 1999 16:51:08 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Alvarez-Estrada",
"R. F.",
""
],
[
"Sanchez-Gomez",
"J. L.",
""
]
] |
quant-ph/9807085 | Gabriel Drobny | B. Hladky, G. Drobny, V. Buzek (Institute of Physics, Bratislava) | Quantum synthesis of 3D vibrational states of trapped ions | latex, 10 pages; see Acta Phys. Slovaca, Special issue on Quantum
Optics and Quantum information
http://www.savba.sk/sav/inst/fyzi/aps/acta98/no3/ | Acta Phys.Slov. 48 (1998) 271-280 | null | null | quant-ph | null | A universal algorithm for a deterministic preparation of arbitrary
three--mode bosonic states is introduced. In particular, we consider
preparation of entangled quantum states of a vibrational motion of an ion
confined in a 3D trapping potential. The target states are established after a
proper sequence of laser stimulated Raman transitions. Stability of the
algorithm with respect to a technical noise is discussed and the distance
(fidelity) of outputs with respect to target states is studied.
| [
{
"version": "v1",
"created": "Thu, 30 Jul 1998 10:53:30 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Hladky",
"B.",
"",
"Institute of Physics, Bratislava"
],
[
"Drobny",
"G.",
"",
"Institute of Physics, Bratislava"
],
[
"Buzek",
"V.",
"",
"Institute of Physics, Bratislava"
]
] |
quant-ph/9807086 | Vladimir Buzek | V. Buzek, M. Hillery, R. Bednik | Controlling the flow of information in quantum cloners: Asymmetric
cloning | latex, 8 pages; see Acta Phys. Slovaca, Special issue on Quantum
Optics and Quantum information
http://www.savba.sk/sav/inst/fyzi/aps/acta98/no3/ | Acta Phys.Slov. 48 (1998) 177-184 | null | null | quant-ph | null | We show that the distribution of information at the output of the quantum
cloner can be efficiently controlled via preparation of the quantum cloner. We
present a universal cloning network with the help of which asymmetric cloning
can be performed.
| [
{
"version": "v1",
"created": "Thu, 30 Jul 1998 11:32:05 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Buzek",
"V.",
""
],
[
"Hillery",
"M.",
""
],
[
"Bednik",
"R.",
""
]
] |
quant-ph/9807087 | Abel Camacho Quinatana | A. Camacho and H. Dehnen | Higgs Field and Localization Problem | latex file, 12 pages | Int.J.Mod.Phys.A14:1711-1720,1999 | 10.1142/S0217751X99000865 | null | quant-ph | null | We analyze the role that the excited states of the Higgs field could play in
a possible solution to the so called localization problem of Quantum Theory. We
seek a solution to the aforementioned point without introducing additional
fundamental constants or extra hypotheses, as has been done in previous works.
The electron and Higgs field do indeed have solitonic solutions. This last
feature renders, in the one-dimensional case, a solution to the localization
problem.
| [
{
"version": "v1",
"created": "Thu, 30 Jul 1998 20:02:26 GMT"
}
] | 2011-07-19T00:00:00 | [
[
"Camacho",
"A.",
""
],
[
"Dehnen",
"H.",
""
]
] |
quant-ph/9807088 | Michael G. Moore | M. G. Moore and P. Meystre | Optical control and entanglement of atomic Schroedinger fields | 4 pages | null | 10.1103/PhysRevA.59.R1754 | null | quant-ph cond-mat | null | We develop a fully quantized model of a Bose-Einstein condensate driven by a
far off-resonant pump laser which interacts with a single mode of an optical
ring cavity. In the linear regime, the cavity mode exhibits spontaneous
exponential gain correlated with the appearance of two atomic field side-modes.
These side-modes and the cavity field are generated in a highly entangled
state, characterized by thermal intensity fluctuations in the individual modes,
but with two-mode correlation functions which violate certain classical
inequalities. By injecting an initial coherent field into the optical cavity
one can significantly decrease the intensity fluctuations at the expense of
reducing the correlations, thus allowing for optical control over the quantum
statistical properties of matter waves.
| [
{
"version": "v1",
"created": "Thu, 30 Jul 1998 23:43:26 GMT"
},
{
"version": "v2",
"created": "Sun, 2 Aug 1998 19:43:23 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Moore",
"M. G.",
""
],
[
"Meystre",
"P.",
""
]
] |
quant-ph/9807089 | M. Dakna | M. Dakna, J. Clausen, L. Knoll and D.-G. Welsch | Generation of arbitrary quantum states of traveling fields | 1 Table and 2 Postscript figures, using Latex; modifications and
changes in Figure 2, Table 1 and Eqs. 11-13,17,18,21 | null | 10.1103/PhysRevA.59.1658 | null | quant-ph | null | We show that any single-mode quantum state can be generated from the vacuum
by alternate application of the coherent displacement operator and the creation
operator. We propose an experimental implementation of the scheme for traveling
optical fields, which is based on field mixings and conditional measurements in
a beam splitter array, and calculate the probability of state generation.
| [
{
"version": "v1",
"created": "Fri, 31 Jul 1998 15:28:55 GMT"
},
{
"version": "v2",
"created": "Mon, 5 Jul 1999 23:48:28 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Dakna",
"M.",
""
],
[
"Clausen",
"J.",
""
],
[
"Knoll",
"L.",
""
],
[
"Welsch",
"D. -G.",
""
]
] |
quant-ph/9807090 | Anthony Chefles | Stephen M. Barnett and Anthony Chefles | Nonlocality Without Inequalities for all Pure Entangled States | null | null | null | null | quant-ph | null | This paper has been withdrawn by the authors.
| [
{
"version": "v1",
"created": "Fri, 31 Jul 1998 16:20:53 GMT"
},
{
"version": "v2",
"created": "Mon, 9 Aug 1999 11:07:16 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Barnett",
"Stephen M.",
""
],
[
"Chefles",
"Anthony",
""
]
] |
quant-ph/9807091 | Michal Horodecki | Pawel Horodecki, Michal Horodecki and Ryszard Horodecki | General teleportation channel, singlet fraction and quasi-distillation | RevTeX, 14 pages, proposition in Sec. VI has been corrected, many
minor corrections | null | null | null | quant-ph | null | We prove a theorem on direct relation between the optimal fidelity $f_{max}$
of teleportation and the maximal singlet fraction $F_{max}$ attainable by means
of trace-preserving LQCC action (local quantum and classical communication).
For a given bipartite state acting on $C^d\otimes C^d$ we have $f_{max}=
{F_{max}d+1\over d+1}$. We assume completely general teleportation scheme
(trace preserving LQCC action over the pair and the third particle in unknown
state). The proof involves the isomorphism between quantum channels and a class
of bipartite states. We also exploit the technique of $U\otimes U^*$ twirling
states (random application of unitary transformation of the above form) and the
introduced analogous twirling of channels. We illustrate the power of the
theorem by showing that {\it any} bound entangled state does not provide better
fidelity of teleportation than for the purely classical channel. Subsequently,
we apply our tools to the problem of the so-called conclusive teleportation,
then reduced to the question of optimal conclusive increasing of singlet
fraction. We provide an example of state for which Alice and Bob have no chance
to obtain perfect singlet by LQCC action, but still singlet fraction
arbitrarily close to unity can be obtained with nonzero probability. We show
that a slight modification of the state has a threshold for singlet fraction
which cannot be exceeded anymore.
| [
{
"version": "v1",
"created": "Fri, 31 Jul 1998 17:02:47 GMT"
},
{
"version": "v2",
"created": "Tue, 2 Mar 1999 14:12:03 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Horodecki",
"Pawel",
""
],
[
"Horodecki",
"Michal",
""
],
[
"Horodecki",
"Ryszard",
""
]
] |
quant-ph/9807092 | Boris A. Kupershmidt | Boris A. Kupershmidt | Quantum differential forms | null | J. Nonlinear Math. Phys. 5 (1998), no. 3, 245-288 | 10.2991/jnmp.1998.5.3.3 | JNMP 4/2002 (Article) | quant-ph | null | Formalism of differential forms is developed for a variety of Quantum and
noncommutative situations.
| [
{
"version": "v1",
"created": "Wed, 1 Jul 1998 00:00:00 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Kupershmidt",
"Boris A.",
""
]
] |
quant-ph/9808001 | Lior Goldenberg | Lior Goldenberg, Lev Vaidman and Stephen Wiesner (Tel-Aviv University) | Quantum Gambling | 4 pages, no figures, RevTex; extensively revised; submitted to
Physical Review Letters | Phys.Rev.Lett.82:3356-3359,1999 | 10.1103/PhysRevLett.82.3356 | null | quant-ph | null | We present a two-party protocol for quantum gambling, a new task closely
related to coin tossing. The protocol allows two remote parties to play a
gambling game, such that in a certain limit it becomes a fair game. No
unconditionally secure classical method is known to accomplish this task.
| [
{
"version": "v1",
"created": "Sun, 2 Aug 1998 22:48:24 GMT"
},
{
"version": "v2",
"created": "Tue, 29 Dec 1998 17:50:43 GMT"
}
] | 2009-01-23T00:00:00 | [
[
"Goldenberg",
"Lior",
"",
"Tel-Aviv University"
],
[
"Vaidman",
"Lev",
"",
"Tel-Aviv University"
],
[
"Wiesner",
"Stephen",
"",
"Tel-Aviv University"
]
] |
quant-ph/9808002 | John A. Vaccaro | John A. Vaccaro | Mean-density Bogoliubov description of inhomogeneous Bose-condensed
gases | 4 pages, 1 figure | null | null | null | quant-ph | null | A mean-density description of spatially-inhomogeneous Bose-condensed gases
based on Bogoliubov's method is introduced. The description assumes only a
large mean atomic density and so remains valid when the mean field collapses
due to phase diffusion. A spread in the number of particles in the condensate
is shown to lead to an anomalous coupling between the condensate and excited
modes. This coupling is due to the dependence of the condensate spatial
wavefunction on particle number and it could, in principle, be used for
reducing particle fluctuations in the condensate.
| [
{
"version": "v1",
"created": "Mon, 3 Aug 1998 12:01:24 GMT"
},
{
"version": "v2",
"created": "Tue, 4 Aug 1998 16:12:26 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Vaccaro",
"John A.",
""
]
] |
quant-ph/9808003 | Jeong-Young Ji | Jeong-Young Ji and Jongbae Hong (Seoul National Univ.) | Heisenberg picture approach to the invariants and the exact quantum
motions for coupled parametric oscillators | 8 pages, revTeX | J.Phys. A31 (1998) L689-L693 | 10.1088/0305-4470/31/39/002 | null | quant-ph | null | For $N$-coupled generalized time-dependent oscillators, primary invariants
and a generalized invariant are found in terms of classical solutions. Exact
quantum motions satisfying the Heisenberg equation of motion are also found.
For number states and coherent states of the generalized invariant, the
uncertainties in positions and momenta are obtained.
| [
{
"version": "v1",
"created": "Tue, 4 Aug 1998 05:10:32 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Ji",
"Jeong-Young",
"",
"Seoul National Univ."
],
[
"Hong",
"Jongbae",
"",
"Seoul National Univ."
]
] |
quant-ph/9808004 | Ananda Dasgupta | Ananda Dasgupta (1) ((1) Saha Institute of Nuclear Physics, Calcutta,
India) | An analytically solvable time dependent Jaynes Cummings model | 7 pages, LaTex, 3 postscript figures | J.Opt.B Quant.Semiclass.Opt.1:14-18,1999 | 10.1088/1464-4266/1/1/003 | SINP/TNP/98-19 | quant-ph | null | Using the underlying su(2) algebra of the Jaynes-Cummings Model (JCM), we
construct a time dependent interaction term that allows analytical solution for
even off-resonance conditions. Exact solutions for the time evolution of any
state has been found. The effect of detuning on the Rabi oscillations and the
collapse and revival of inversion is indicated. It is also shown that at
resonance, the time dependent JCM is analytically solvable for an arbitrary
interaction term.
| [
{
"version": "v1",
"created": "Tue, 4 Aug 1998 08:19:55 GMT"
}
] | 2011-02-11T00:00:00 | [
[
"Dasgupta",
"Ananda",
""
]
] |
quant-ph/9808005 | Milos V. Lokajicek | Milos V. Lokajicek | Locality problem, Bell's inequalities and EPR experiments | null | null | null | PRA-HEP-98/5 | quant-ph | null | The question has been solved whether Bell's inequalities cover all possible
kinds of hidden-variable theories. It has been shown that the given nequalities
can be hardly derived when the changing space position of photon-pair source
together with the microscopic space structure of measuring devices are taken
into account; and when corresponding impact parameters (i.e., exact impact
points) of photons in individual measuring devices (polarizers) influence
measured values, in addition to usually considered characteristics.
| [
{
"version": "v1",
"created": "Tue, 4 Aug 1998 14:57:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Lokajicek",
"Milos V.",
""
]
] |
quant-ph/9808006 | kazutomu Shiokawa | K. Shiokawa, B. L. Hu | Finite Number and Finite Size Effects in Relativistic Bose-Einstein
Condensation | 18 pages, 9 figures, Fig.3 replaced, to appear in Physical Review D | Phys.Rev. D60 (1999) 105016 | 10.1103/PhysRevD.60.105016 | UMDPP98-102 | quant-ph cond-mat | null | Bose-Einstein condensation of a relativistic ideal Bose gas in a rectangular
cavity is studied. Finite size corrections to the critical temperature are
obtained by the heat kernel method. Using zeta-function regularization of
one-loop effective potential, lower dimensional critical temperatures are
calculated. In the presence of strong anisotropy, the condensation is shown to
occur in multisteps. The criteria of this behavior is that critical
temperatures corresponding to lower dimensional systems are smaller than the
three dimensional critical temperature.
| [
{
"version": "v1",
"created": "Tue, 4 Aug 1998 16:11:10 GMT"
},
{
"version": "v2",
"created": "Fri, 18 Jun 1999 20:08:03 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Shiokawa",
"K.",
""
],
[
"Hu",
"B. L.",
""
]
] |
quant-ph/9808007 | Robert Garisto | Robert Garisto and Lucien Hardy | Entanglement of projection and a new class of quantum erasers | 12pp, 2 figs, LATEX (Revtex) | Phys.Rev. A60 (1999) 827 | 10.1103/PhysRevA.60.827 | null | quant-ph hep-th | null | We define a new measurement of entanglement, the entanglement of projection,
and find that it is natural to write the entanglements of formation and
assistance in terms of it. Our measure allows us to describe a new class of
quantum erasers which restore entanglement rather than just interference. Such
erasers can be implemented with simple quantum computer components. We propose
realistic optical versions of these erasers.
| [
{
"version": "v1",
"created": "Tue, 4 Aug 1998 23:00:00 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Garisto",
"Robert",
""
],
[
"Hardy",
"Lucien",
""
]
] |
quant-ph/9808008 | Vladimir Z. Nuri | V. Z. Nuri | Local, deterministic hidden variable theories based on a loophole in
Bell's theorem | 21 pages, 7 figures, LaTeX2e | null | null | null | quant-ph | null | This paper furthers the long historical examination of and debate on the
foundations of quantum mechanics (QM) by presenting two local hidden variable
(LHV) rules in the context of the EPRB experiment which violate Bell's
inequality, but which are nevertheless local and deterministic under reasonable
definitions of the terms, and coincide approximately with the conventional QM
prediction. The theories are based on the general idea of probabilistic
detection of particles depending on an interaction of hidden variables within
the measuring device and particle, and relate mathematically to Fourier
analysis. The crucial discrepancy of variations in the hidden variable
distribution based on relative polarizer orientations is isolated which
invalidates assumptions in Bell-type theorems. The first theory can be analyzed
completely symbolically whereas the second was analyzed using numerical
methods. The properties of the second in particular are shown to be
approximately consistent with the reported results and uncertainties in all
three Aspect experiments. Variation in the total photon pairs detected over
orientations is shown to be a basic characteristic of these theories. Some
comments on the relevance of active vs. passive locality are made. Two sections
consider these ideas relative to energy conservation and the measurement
problem (collapse of the wavefunction). One section proposes new experiments.
| [
{
"version": "v1",
"created": "Wed, 5 Aug 1998 01:03:57 GMT"
},
{
"version": "v2",
"created": "Wed, 5 Aug 1998 22:18:11 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Nuri",
"V. Z.",
""
]
] |
quant-ph/9808009 | Soren Have Hansen | O.E. Barndorff-Nielsen and R.D. Gill | Fisher information in quantum statistics | This version replaces the previous versions of February 1999 (titled
'An Example of Non-Attainability of Expected Quantum Information') and that
of November 1999. Proofs and results are much improved. To appear in J. Phys.
A | J.Phys. A30 (2000) 4481-4490 | 10.1088/0305-4470/33/24/306 | null | quant-ph math.ST stat.TH | null | Braunstein and Caves (1994) proposed to use Helstrom's {\em quantum
information} number to define, meaningfully, a metric on the set of all
possible states of a given quantum system. They showed that the quantum
information is nothing else than the maximal Fisher information in a
measurement of the quantum system, maximized over all possible measurements.
Combining this fact with classical statistical results, they argued that the
quantum information determines the asymptotically optimal rate at which
neighbouring states on some smooth curve can be distinguished, based on
arbitrary measurements on $n$ identical copies of the given quantum system.
We show that the measurement which maximizes the Fisher information typically
depends on the true, unknown, state of the quantum system. We close the
resulting loophole in the argument by showing that one can still achieve the
same, optimal, rate of distinguishability, by a two stage adaptive measurement
procedure.
When we consider states lying not on a smooth curve, but on a manifold of
higher dimension, the situation becomes much more complex. We show that the
notion of ``distinguishability of close-by states'' depends strongly on the
measurement resources one allows oneself, and on a further specification of the
task at hand. The quantum information matrix no longer seems to play a central
role.
| [
{
"version": "v1",
"created": "Wed, 5 Aug 1998 11:04:35 GMT"
},
{
"version": "v2",
"created": "Tue, 9 Feb 1999 11:39:15 GMT"
},
{
"version": "v3",
"created": "Mon, 15 Nov 1999 11:46:29 GMT"
},
{
"version": "v4",
"created": "Wed, 23 Feb 2000 11:44:32 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Barndorff-Nielsen",
"O. E.",
""
],
[
"Gill",
"R. D.",
""
]
] |
quant-ph/9808010 | Kirill Alekseev | Kirill N. Alekseev | Squeezed Light Generation in Nonlinear System with Chaotic Dynamics | 12 pages, RevTEX (EPSF-style), 6 figures | Opt.Commun. 116 (1994) 468-477 | 10.1016/0030-4018(95)91254-Y | null | quant-ph chao-dyn nlin.CD physics.optics | null | The squeezing in a nonlinear system with chaotic dynamics is considered. The
model describing interaction of collection of two-level atoms with a
single-mode of self-consistent field and an external field is analyzed. It is
shown that in the semiclassical limit, in contrast to the regular behaviour,
the chaotic dynamics result in: (i) an increase in squeezing, (ii) unstable
squeezing and contraction of time intervals of squeezing on large enough times.
The possibility of the experimental observation of the described effects is
discussed.
| [
{
"version": "v1",
"created": "Thu, 6 Aug 1998 12:05:21 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Alekseev",
"Kirill N.",
""
]
] |
quant-ph/9808011 | Sharon Jensen | H. Pierre Noyes and Tom Etter | Process, System, Causality, and Quantum Mechanics, A Psychoanalysis of
Animal Faith | LaTex, 86 pages | Phys.Essays 12 (1999) 733-765 | 10.4006/1.3028803 | SLAC-PUB-7890 | quant-ph | null | We shall argue in this paper that a central piece of modern physics does not
really belong to physics at all but to elementary probability theory. Given a
joint probability distribution J on a set of random variables containing x and
y, define a link between x and y to be the condition x=y on J. Define the {\it
state} D of a link x=y as the joint probability distribution matrix on x and y
without the link. The two core laws of quantum mechanics are the Born
probability rule, and the unitary dynamical law whose best known form is the
Schrodinger's equation. Von Neumann formulated these two laws in the language
of Hilbert space as prob(P) = trace(PD) and D'T = TD respectively, where P is a
projection, D and D' are (von Neumann) density matrices, and T is a unitary
transformation. We'll see that if we regard link states as density matrices,
the algebraic forms of these two core laws occur as completely general theorems
about links. When we extend probability theory by allowing cases to count
negatively, we find that the Hilbert space framework of quantum mechanics
proper emerges from the assumption that all D's are symmetrical in rows and
columns. On the other hand, Markovian systems emerge when we assume that one of
every linked variable pair has a uniform probability distribution. By
representing quantum and Markovian structure in this way, we see clearly both
how they differ, and also how they can coexist in natural harmony with each
other, as they must in quantum measurement, which we'll examine in some detail.
Looking beyond quantum mechanics, we see how both structures have their special
places in a much larger continuum of formal systems that we have yet to look
for in nature.
| [
{
"version": "v1",
"created": "Thu, 6 Aug 1998 21:41:25 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Noyes",
"H. Pierre",
""
],
[
"Etter",
"Tom",
""
]
] |
quant-ph/9808012 | Sara Schneider | Sara Schneider, Daniel F.V. James, Gerard J. Milburn | Method of quantum computation with ``hot'' trapped ions | 4 pages, 2 figures, submitted to PRL | null | null | null | quant-ph | null | We present a novel method of performing quantum logic gates in trapped ion
quantum computers which does not require the ions to be cooled down to their
vibrational center of mass (CM) mode ground state. Our scheme employs adiabatic
passages and the conditional phase shift first investigated by D'Helon and
Milburn (C.~D'Helon and G.J.~Milburn, Phys. Rev. A {\bf 54}, 5141 (1996)).
| [
{
"version": "v1",
"created": "Fri, 7 Aug 1998 04:26:32 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Schneider",
"Sara",
""
],
[
"James",
"Daniel F. V.",
""
],
[
"Milburn",
"Gerard J.",
""
]
] |
quant-ph/9808013 | Pawel Caban | Pawel Caban and Jakub Rembieli\'nski (Department of Theoretical
Physics, University of Lodz, Lodz, Poland) | Lorentz-covariant quantum mechanics and preferred frame | 21 pages, LaTeX file, no figures | Phys.Rev. A59 (1999) 4187-4196 | 10.1103/PhysRevA.59.4187 | KFT UL 10/98 | quant-ph | null | In this paper the relativistic quantum mechanics is considered in the
framework of the nonstandard synchronization scheme for clocks. Such a
synchronization preserves Poincar{\'e} covariance but (at least formally)
distinguishes an inertial frame. This enables to avoid the problem of a
noncausal transmision of information related to breaking of the Bell's
inequalities in QM. Our analysis has been focused mainly on the problem of
existence of a proper position operator for massive particles. We have proved
that in our framework such an operator exists for particles with arbitrary
spin. It fulfills all the requirements: it is Hermitean and covariant, it has
commuting components and moreover its eigenvectors (localised states) are also
covariant. We have found the explicit form of the position operator and have
demonstrated that in the preferred frame our operator coincides with the
Newton--Wigner one. We have also defined a covariant spin operator and have
constructed an invariant spin square operator. Moreover, full algebra of
observables consisting of position operators, fourmomentum operators and spin
operators is manifestly Poincar\'e covariant in this framework. Our results
support expectations of other authors (Bell, Eberhard) that a consistent
formulation of quantum mechanics demands existence of a preferred frame.
| [
{
"version": "v1",
"created": "Fri, 7 Aug 1998 14:38:19 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Caban",
"Pawel",
"",
"Department of Theoretical\n Physics, University of Lodz, Lodz, Poland"
],
[
"Rembieliński",
"Jakub",
"",
"Department of Theoretical\n Physics, University of Lodz, Lodz, Poland"
]
] |
quant-ph/9808014 | Luis Santos | Luis Santos and Maciej Lewenstein | Dynamical Cooling of Trapped Gases I: One Atom Problem | LaTeX file with 8 pages, 7 eps figures. Submitted to Phys. Rev. A | null | 10.1103/PhysRevA.59.613 | null | quant-ph | null | We study the laser cooling of one atom in an harmonic trap beyond the
Lamb-Dicke regime. By using sequences of laser pulses of different detunings we
show that the atom can be confined into just one state of the trap, either the
ground state or an excited state of the harmonic potential. The last can be
achieved because under certain conditions an excited state becomes a dark
state. We study the problem in one and two dimensions. For the latter case a
new cooling mechanism is possible, based on the destructive interference
between the effects of laser fields in different directions, which allows the
creation of variety of dark states. For both, one and two dimensional cases,
Monte Carlo simulations of the cooling dynamics are presented.
| [
{
"version": "v1",
"created": "Sat, 8 Aug 1998 09:37:15 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Santos",
"Luis",
""
],
[
"Lewenstein",
"Maciej",
""
]
] |
quant-ph/9808015 | Madjid Aboolhassani | M. Abolhasani and M. Golshani | Born's Principle, Action-Reaction Problem and Arrow of Time | 7 pages, Latex file, to appear in Foundations of Physics Letters | Found.Phys.Lett. 12 (1999) 299-306 | null | IPM-97-202 | quant-ph | null | We try to obtain Born's principle as a result of a subquantum heat death,
using classical ${\cal H}$-theorem and the definition of a proper quantum
${\cal H}$-theorem, within the framwork of Bohm's theory. We shall show the
possibility of solving the problem of action-reaction asymmetry present in
Bohm's theory and the arrow of time problem in our procedure.
| [
{
"version": "v1",
"created": "Mon, 10 Aug 1998 08:08:02 GMT"
},
{
"version": "v2",
"created": "Tue, 18 May 1999 04:20:16 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Abolhasani",
"M.",
""
],
[
"Golshani",
"M.",
""
]
] |
quant-ph/9808016 | Christian Grosche | Christian Grosche | Path Integrals with Kinetic Coupling Potentials | 8 pages., LateX, 1 figure (postscript) | null | 10.1023/A:1021149710668 | DESY 98-100 | quant-ph | null | Path integral solutions with kinetic coupling potentials $\propto p_1p_2$ are
evaluated. As examples I give a Morse oscillator, i.e., a model in molecular
physics, and the double pendulum in the harmonic approximation. The former is
solved by some well-known path integral techniques, whereas the latter by an
affine transformation.
| [
{
"version": "v1",
"created": "Mon, 10 Aug 1998 10:01:45 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Grosche",
"Christian",
""
]
] |
quant-ph/9808017 | Villain Pierre | Villain Pierre and Lewenstein Maciej | Dephasing of Josephson oscillations between two coupled Bose-Einstein
condensates | 14 pages. Submitted to Phys. Rev. A | null | null | null | quant-ph | null | We study the dynamics of the relative phase between two Bose-Einstein
condensates coupled via collisions and via a Josephson-like coupling. We derive
the equations of the motion for the relative phase and the relative number
operators from the second quantized Hamiltonian of the system using a quantum
field theoretical approach. We distinguish the cases in which the two
condensates are in the same trap or in two different traps and study the
influence of this difference on the first order correlation function of atomic
fields. In identical traps this function does not undergo dephasing. We
calculate the dephasing time for the case of different traps.
| [
{
"version": "v1",
"created": "Tue, 11 Aug 1998 10:16:08 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Pierre",
"Villain",
""
],
[
"Maciej",
"Lewenstein",
""
]
] |
quant-ph/9808018 | Anthony Chefles | Anthony Chefles and Stephen M. Barnett | Quantum State Separation, Unambiguous Discrimination and Exact Cloning | RevTeX, 5 pages postscript | J.Phys.A31:10097-10103,1998 | 10.1088/0305-4470/31/50/007 | null | quant-ph | null | Unambiguous discrimination and exact cloning reduce the square-overlap
between quantum states, exemplifying the more general type of procedure we term
state separation. We obtain the maximum probability with which two equiprobable
quantum states can be separated by an arbitrary degree, and find that the
established bounds on the success probabilities for discrimination and cloning
are special cases of this general bound. The latter also gives the maximum
probability of successfully producing N exact copies of a quantum system whose
state is chosen secretly from a known pair, given M initial realisations of the
state, where N>M. We also discuss the relationship between this bound and that
on unambiguous state discrimination.
| [
{
"version": "v1",
"created": "Tue, 11 Aug 1998 11:38:03 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Chefles",
"Anthony",
""
],
[
"Barnett",
"Stephen M.",
""
]
] |
quant-ph/9808019 | Milos V. Lokajicek | Milos V. Lokajicek | Are quantum teleportation and cryptography predicted by quantum
mechanics? | null | null | null | PRA-HEP-98/6 | quant-ph | null | It has been shown that the predictions of some new phenomena (e.g.,
teleportation and cryptography) are based on some assumptions added to the
quantum-mechanical model or modifying some of its basic axioms. The hitherto
experiments presented as a support of the mentioned phenomena may be hardly
regarded as sufficient, as they may be interpreted alternatively on the basis
of simple interference processes.
| [
{
"version": "v1",
"created": "Wed, 12 Aug 1998 12:34:36 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Lokajicek",
"Milos V.",
""
]
] |
quant-ph/9808020 | Bg Sidharth | B.G. Sidharth | Quantum Mechanical Black Holes: Towards a Unification of Quantum
Mechanics and General Relativity | 32 pages, TeX | Indian J.Pure Appl.Phys. 35 (1997) 456-471 | null | null | quant-ph gr-qc | null | In this paper, starting from vortices we are finally lead to a treatment of
Fermions as Kerr-Newman type Black Holes wherein we identify the horizon at the
particle's Compton wavelength periphery. A naked singularity is avoided and the
singular processes inside the horizon of the Black Hole are identified with
Quantum Mechanical effects within the Compton wavelength. Inertial mass,
gravitation, electromagnetism and even QCD type interactions emerge from such a
description including relative strengths and also other features like the
anomalous gyromagnetic ratio, the discreteness of the charge, the reason why
the electron's field emerges from Newman's complex transformation in General
Relativity, a rationale for the left handedness of neutrinos and the
matter-antimatter imbalance. This model describes the most fundamental stable
Fermions viz., the electrons, neutrinos and approximately the quarks. It also
harmoniously unifies the hydrodynamical, monopole and classical relativistic
perspectives.
| [
{
"version": "v1",
"created": "Wed, 12 Aug 1998 15:37:38 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sidharth",
"B. G.",
""
]
] |
quant-ph/9808021 | Haret Rosu | H.C. Rosu, C. Castro | q deformation by intertwining with application to the singular
oscillator | 10 pages, accepted at Phys. Lett. A | Phys.Lett. A264 (2000) 350-356 | 10.1016/S0375-9601(99)00846-4 | null | quant-ph | null | We present a version of q-deformed calculus based on deformed counterparts of
Darboux intertwining operators. The case in which the deformed transformation
function is of the vacuum type is detailed, but the extension to counterparts
of excited states used as Darboux transformation functions is also formally
discussed. The method leads to second-order Fokker-Planck-like deformed
operators which may be considered as supersymmetric partners, though for a sort
of q-deformed open systems, i.e., those possessing q nonlocal drift terms,
potential part, as well as q-spreaded vacuum fluctuations. The undeformed limit
corresponds to the conservative case, since all q nonlocalities wash out. The
procedure is applied to the x^{-2} singular oscillator, for which we also
present a formal q generalization of the Bagrov-Samsonov coherent states
| [
{
"version": "v1",
"created": "Wed, 12 Aug 1998 22:08:31 GMT"
},
{
"version": "v2",
"created": "Thu, 13 Aug 1998 23:11:18 GMT"
},
{
"version": "v3",
"created": "Sat, 15 Aug 1998 15:35:01 GMT"
},
{
"version": "v4",
"created": "Sat, 4 Dec 1999 16:53:22 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Rosu",
"H. C.",
""
],
[
"Castro",
"C.",
""
]
] |
quant-ph/9808022 | Lev Vaidman | L. Vaidman | Variations on the Theme of the Greenberger-Horne-Zeilinger Proof | 14 pages, 2eps figures | Found.Phys. 29 (1999) 615-630 | null | null | quant-ph | null | Three arguments based on the Greenberger-Horne-Zeilinger (GHZ) proof of the
nonexistence of local hidden variables are presented. The first is a
description of a simple game which a team that uses the GHZ method will always
win. The second uses counterfactuals in an attempt to show that quantum theory
is nonlocal in a stronger sense than is implied by the nonexistence of local
hidden variables and the third describes peculiar features of time-symmetrized
counterfactuals in quantum theory.
| [
{
"version": "v1",
"created": "Thu, 13 Aug 1998 20:15:31 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Vaidman",
"L.",
""
]
] |
quant-ph/9808023 | Ariel Caticha | Ariel Caticha | Probability and Entropy in Quantum Theory | Presented at the 18th International Workshop on Maximum Entropy and
Bayesian Methods, MaxEnt '98, (27-31 July 1998, Garching, Germany) In version
2 an error on page 7 is corrected. Results and conclusions remain unchanged | null | null | null | quant-ph cond-mat.stat-mech gr-qc math.PR | null | Entropic arguments are shown to play a central role in the foundations of
quantum theory. We prove that probabilities are given by the modulus squared of
wave functions, and that the time evolution of states is linear and also
unitary.
| [
{
"version": "v1",
"created": "Fri, 14 Aug 1998 20:57:07 GMT"
},
{
"version": "v2",
"created": "Fri, 25 Sep 1998 20:49:06 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Caticha",
"Ariel",
""
]
] |
quant-ph/9808024 | Todd A. Brun | Todd A. Brun (Carnegie Mellon University), James B. Hartle (Physics,
UCSB) | Entropy of Classical Histories | 35 pages RevTeX 3.0 + 5 figures (postscript). Minor corrections and
typos. To appear in Physical Review E | Phys.Rev. E59 (1999) 6370-6380 | 10.1103/PhysRevE.59.6370 | NSF-ITP-97-102 | quant-ph gr-qc | null | We consider a number of proposals for the entropy of sets of classical
coarse-grained histories based on the procedures of Jaynes, and prove a series
of inequalities relating these measures. We then examine these as a function of
the coarse-graining for various classical systems, and show explicitly that the
entropy is minimized by the finest-grained description of a set of histories.
We propose an extension of the second law of thermodynamics to the entropy of
histories. We briefly discuss the implications for decoherent or consistent
history formulations of quantum mechanics.
| [
{
"version": "v1",
"created": "Sat, 15 Aug 1998 01:24:19 GMT"
},
{
"version": "v2",
"created": "Thu, 22 Apr 1999 20:11:16 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Brun",
"Todd A.",
"",
"Carnegie Mellon University"
],
[
"Hartle",
"James B.",
"",
"Physics,\n UCSB"
]
] |
quant-ph/9808025 | Li Weigang | Li Weigang (U. of Brasilia) | A Study of Parallel Self-Organizing Map | 27 pages, 9 figures | null | null | null | quant-ph | null | A Parallel Self-Organizing Map (Parallel-SOM) is proposed to modify Kohonen's
SOM in parallel computing environment. In this model, two separate layers of
neurons are connected together. The number of neurons in both layers and
connections between them is the product of the number of all elements of input
signals and the number of possible classification of the data. With this
structure the conventional repeated learning procedure is modified to learn
just once. The once learning manner is more similar to human learning and
memorizing activities. During training, weight updating is managed through a
sequence of operations among some transformation and operation matrices. Every
connection between neurons of input/output layers is considered as a
independent processor. In this way, all elements of the Euclidean distance
matrix and weight matrix are calculated simultaneously. The minimum distance of
every line of distance matrix can be found by Grover's search algorithm. This
synchronization feature improves the weight updating sequence significantly.
With a typical classification example, the convergence result demonstrates
efficient performance of Parallel-SOM. Theoretic analysis and proofs also show
some important properties of proposed model. Especially, the paper proves that
Parallel-SOM has the same convergence property as Kohonen's SOM, but the
complexity of former is reduced obviously.
| [
{
"version": "v1",
"created": "Mon, 17 Aug 1998 12:44:50 GMT"
},
{
"version": "v2",
"created": "Thu, 20 Aug 1998 23:31:41 GMT"
},
{
"version": "v3",
"created": "Mon, 19 Oct 1998 01:31:03 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Weigang",
"Li",
"",
"U. of Brasilia"
]
] |
quant-ph/9808026 | Alexander Korotkov | Alexander N. Korotkov | Continuous quantum measurement with particular output: pure wavefunction
evolution instead of decoherence | short version of quant-ph/9807051 (4 pages, 2 figures) | null | null | null | quant-ph cond-mat.mes-hall | null | We consider a continuous measurement of a two-level system (double-dot) by
weakly coupled detector (tunnel point contact nearby). While usual treatment
leads to the gradual system decoherence due to the measurement, we show that
the knowledge of the measurement result can restore the pure wavefunction at
any time (this can be experimentally verified). The formalism allows to write a
simple Langevin equation for the random evolution of the system density matrix
which is reflected and caused by the stochastic detector output. Gradual
wavefunction ``collapse'' and quantum Zeno effect are naturally described by
the equation.
| [
{
"version": "v1",
"created": "Mon, 17 Aug 1998 18:03:48 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Korotkov",
"Alexander N.",
""
]
] |
quant-ph/9808027 | Cristopher Moore | Cristopher Moore and Martin Nilsson | Parallel Quantum Computation and Quantum Codes | null | null | null | null | quant-ph math.QA | null | We propose a definition of QNC, the quantum analog of the efficient parallel
class NC. We exhibit several useful gadgets and prove that various classes of
circuits can be parallelized to logarithmic depth, including circuits for
encoding and decoding standard quantum error-correcting codes, or more
generally any circuit consisting of controlled-not gates, controlled pi-shifts,
and Hadamard gates. Finally, while we note the Quantum Fourier Transform can be
parallelized to linear depth, we conjecture that an even simpler `staircase'
circuit cannot be parallelized to less than linear depth, and might be used to
prove that QNC < QP.
| [
{
"version": "v1",
"created": "Mon, 17 Aug 1998 22:56:57 GMT"
}
] | 2009-09-25T00:00:00 | [
[
"Moore",
"Cristopher",
""
],
[
"Nilsson",
"Martin",
""
]
] |
quant-ph/9808028 | Alberto Carlini | A. Carlini and A. Hosoya | An Alternative Algorithm for the Database Search Problem on a Quantum
Computer | the paper has been withdrawn | null | null | null | quant-ph | null | The paper has been withdrawn
| [
{
"version": "v1",
"created": "Tue, 18 Aug 1998 09:15:38 GMT"
},
{
"version": "v2",
"created": "Thu, 3 Sep 1998 12:24:43 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Carlini",
"A.",
""
],
[
"Hosoya",
"A.",
""
]
] |
quant-ph/9808029 | null | Guang-jiong Ni, Weimin Zhou, Jun Yan (Department of Physics, Fudan
University, Shanghai, P.R.China) | Why can an electron mass vary from zero to infinity? | 8 pages, Latex, No Figure | null | null | null | quant-ph | null | When a particle is in high speed or bound in the Coulomb potential of point
nucleus, the variation of its mass can be ascribed to the variation of relative
ratio of hiding antimatter to matter in the particle. At two limiting cases,
the ratio approaches to 1.
| [
{
"version": "v1",
"created": "Tue, 18 Aug 1998 04:12:02 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ni",
"Guang-jiong",
"",
"Department of Physics, Fudan\n University, Shanghai, P.R.China"
],
[
"Zhou",
"Weimin",
"",
"Department of Physics, Fudan\n University, Shanghai, P.R.China"
],
[
"Yan",
"Jun",
"",
"Department of Physics, Fudan\n University, Shanghai, P.R.China"
]
] |
quant-ph/9808030 | Barbara M. Terhal | C.H. Bennett, D.P. DiVincenzo, T. Mor, P.W. Shor, J.A. Smolin, and
B.M. Terhal | Unextendible Product Bases and Bound Entanglement | 4 pages RevTex + 1 eps fig. This is version 2 with many changes and
simplifications, and an additional author | Phys.Rev.Lett. 82 (1999) 5385 | 10.1103/PhysRevLett.82.5385 | null | quant-ph | null | An unextendible product basis (UPB) for a multipartite quantum system is an
incomplete orthogonal product basis whose complementary subspace contains no
product state. We give examples of UPBs, and show that the uniform mixed state
over the subspace complementary to any UPB is a bound entangled state. We
exhibit a tripartite 2x2x2 UPB whose complementary mixed state has tripartite
entanglement but no bipartite entanglement, i.e. all three corresponding 2x4
bipartite mixed states are unentangled. We show that members of a UPB are not
perfectly distinguishable by local POVMs and classical communication.
| [
{
"version": "v1",
"created": "Tue, 18 Aug 1998 22:10:54 GMT"
},
{
"version": "v2",
"created": "Fri, 12 Feb 1999 15:07:08 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Bennett",
"C. H.",
""
],
[
"DiVincenzo",
"D. P.",
""
],
[
"Mor",
"T.",
""
],
[
"Shor",
"P. W.",
""
],
[
"Smolin",
"J. A.",
""
],
[
"Terhal",
"B. M.",
""
]
] |
quant-ph/9808031 | Bg Sidharth | B.G. Sidharth | The Universe of Fluctuations | 18 pages, TeX, paper appeared in the International Journal of Modern
Physics A, vol.13, No.15, 1998 | Int.J.Mod.Phys. A13 (1998) 2599-2612 | 10.1142/S0217751X98001335 | null | quant-ph gr-qc hep-th | null | We discuss the recent model of a Quantum Mechanical Black Hole (QMBH) which
describes the most fundamental known particles, the leptons and approximately
the quarks in terms of the Kerr-Newman Black Hole with a naked singularity
shielded by Zitterbewegung effects. This goes beyond the Zitterbewegung and
self interaction models of Barut and Bracken, Hestenes, Chacko and others and
provides a unified picture which amongst other things gives a rationale for and
an insight into: 1. The apparently inexplicable reason why complex space-time
transformations lead to the Kerr-Newman metric in General Relativity. 2. The
value of the fine structure constant. 3. The ratio between electromagnetic and
gravitational interaction strengths. 4. The anomalous gyromagnetic ratio for
the electron. 5. Why the neutrino is left-handed. 6. Why the charge is
discrete. In the spirit of Effective Field Theories, this model provides an
alternative formalism for Quantum Theory and also for its combination with
General Relativity. Finally a mechanism for the formation of these QMBH or
particles is explored within the framework of Stochastic Electrodynamics, QED
and Quantum Statistical Mechanics. The cosmological implications are then
examined. It turns out that a surprisingly large number of facts, including
some which were hitherto inexplicable, follow as a consequence of the model.
These include a theoretical deduction of the Mass, Radius and Age of the
Universe, also the values of Hubble's constant and the Cosmological constant.
| [
{
"version": "v1",
"created": "Wed, 19 Aug 1998 01:39:24 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Sidharth",
"B. G.",
""
]
] |
quant-ph/9808032 | L. Sriramkumar | Gilad Gour and L. Sriramkumar | Will small particles exhibit Brownian motion in the quantum vacuum? | 31 pages, LaTeX, Final version, To appear in Foundations of Physics | Found.Phys. 29 (1999) 1917-1949 | null | null | quant-ph gr-qc | null | The Brownian motion of small particles interacting with a field at a finite
temperature is a well-known and well-understood phenomenon. At zero
temperature, even though the thermal fluctuations are absent, quantum fields
still possess vacuum fluctuations. It is then interesting to ask whether a
small particle that is interacting with a quantum field will exhibit Brownian
motion when the quantum field is assumed to be in the vacuum state. In this
paper, we study the cases of a small charge and an imperfect mirror interacting
with a quantum scalar field in (1+1) dimensions. Treating the quantum field as
a classical stochastic variable, we write down a Langevin equation for the
particles. We show that the results we obtain from such an approach agree with
the results obtained from the fluctuation-dissipation theorem. Unlike the
finite temperature case, there exists no special frame of reference at zero
temperature and hence it is essential that the particles do not break Lorentz
invariance. We find that that the scalar charge breaks Lorentz invariance,
whereas the imperfect mirror does not. We conclude that small particles such as
the imperfect mirror {\it will} exhibit Brownian motion even in the quantum
vacuum, but this effect can be so small that it may prove to be difficult to
observe it experimentally.
| [
{
"version": "v1",
"created": "Wed, 19 Aug 1998 10:34:20 GMT"
},
{
"version": "v2",
"created": "Sun, 21 Nov 1999 01:54:17 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gour",
"Gilad",
""
],
[
"Sriramkumar",
"L.",
""
]
] |
quant-ph/9808033 | Abel Camacho Quinatana | A. Camacho and A. Camacho-Galvan | Continuous quantum measurements of a particle in a Paul trap | Latex file, 10 pages | Phys.Lett. A247 (1998) 373-379 | 10.1016/S0375-9601(98)00586-6 | null | quant-ph | null | We calculate the propagator of a particle caught in a Paul trap and subject
to the continuous quantum measurement of its position. The probabilities of the
measurement outputs, the possible trajectories of the particle, are also found.
This enables us to propose a series of experiments that would allow to confront
the predictions of one of the models that describe the interaction between a
measured quantum system and measuring device, namely the so called Restricted
Path-Integral Formalism, with the experiment.
| [
{
"version": "v1",
"created": "Wed, 19 Aug 1998 18:32:25 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Camacho",
"A.",
""
],
[
"Camacho-Galvan",
"A.",
""
]
] |
quant-ph/9808034 | Taksu Cheon | Taksu Cheon (Kochi Tech & KEK, Tsukuba) and T. Shigehara (Saitama U) | Some Aspects of Generalized Contact Interaction in One-Dimensional
Quantum Mechanics | Talk presented at The 7th International Conference on Mathematical
Results in Quantum Mechanics (Qmath7), June 22-26, 1998, Prague, Czechland | null | null | null | quant-ph cond-mat hep-th nlin.SI nucl-th solv-int | null | We construct a one-dimensional contact interaction ($\epsilon$ potential)
which induces the discontinuity of the wave function while keeping its
derivative continuous. By combining the $\epsilon$ potential and the Dirac's
$\delta$ function, we construct most general one-dimensional contact
interactions allowable under the time reversal symmetry. We present some
elementary results for the scattering problem which suggest a dual relation
between $\delta$ and $\epsilon$ potentials.
| [
{
"version": "v1",
"created": "Thu, 20 Aug 1998 05:06:20 GMT"
},
{
"version": "v2",
"created": "Mon, 31 Aug 1998 07:24:34 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Cheon",
"Taksu",
"",
"Kochi Tech & KEK, Tsukuba"
],
[
"Shigehara",
"T.",
"",
"Saitama U"
]
] |
quant-ph/9808035 | S. V. Stepkin | S.S.Sannikov (Physico-Technical Institute, Kharkov, Ukraine) and
A.A.Stanislavsky (Institute of Radio Astronomy, Kharkov, Ukraine) | Charge Renormalization in a New Kind of Non-Local Quantum
Electrodynamics | RevTeX, 6 pages | null | null | null | quant-ph | null | The goal of this message is to calculate radiative corrections to the
Sommerfeld fine structure constant in the framework of a new QED in which
particles are described by bilocal fields. The bare constant is 1/136 where 136
is a dimension of the dynamical group of the bihamiltonian system underlying
the suggested elementary particle theory. Our calculations in the second order
of perturbation theory give the renormalized Sommerfeld constant 1/137.0345. We
believe the difference (137.0359 - 137.0345) between corresponding experimental
and theoretical values may be understood as corrections of the fourth order.
| [
{
"version": "v1",
"created": "Thu, 20 Aug 1998 12:40:48 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sannikov",
"S. S.",
"",
"Physico-Technical Institute, Kharkov, Ukraine"
],
[
"Stanislavsky",
"A. A.",
"",
"Institute of Radio Astronomy, Kharkov, Ukraine"
]
] |
quant-ph/9808036 | Paolo-Zanardi | Paolo Zanardi (1 and 2) and Fausto Rossi (1 and 3) ((1) Istituto
Nazionale per la Fisica della Materia (INFM) (2) Institute for Scientific
Interchange Foundation (ISI), and Unit\`a INFM, Politecnico di Torino (3)
Dipartimento di Fisica, Universit\`a di Modena) | Subdecoherent Information Encoding in a Quantum-Dot Array | 12 pages LaTeX, 5 postscript figures. Final version accepted by PRB | Phys.Rev.B59:8170,1999 | 10.1103/PhysRevB.59.8170 | null | quant-ph cond-mat | null | A potential implementation of quantum-information schemes in semiconductor
nanostructures is studied. To this end, the formal theory of quantum encoding
for avoiding errors is recalled and the existence of noiseless states for model
systems is discussed. Based on this theoretical framework, we analyze the
possibility of designing noiseless quantum codes in realistic semiconductor
structures. In the specific implementation considered, information is encoded
in the lowest energy sector of charge excitations of a linear array of quantum
dots. The decoherence channel considered is electron-phonon coupling We show
that besides the well-known phonon bottleneck, reducing single-qubit
decoherence, suitable many-qubit initial preparation as well as register design
may enhance the decoherence time by several orders of magnitude. This behaviour
stems from the effective one-dimensional character of the phononic environment
in the relevant region of physical parameters.
| [
{
"version": "v1",
"created": "Fri, 21 Aug 1998 10:32:50 GMT"
},
{
"version": "v2",
"created": "Thu, 19 Nov 1998 17:06:34 GMT"
}
] | 2011-08-11T00:00:00 | [
[
"Zanardi",
"Paolo",
"",
"1 and 2"
],
[
"Rossi",
"Fausto",
"",
"1 and 3"
]
] |
quant-ph/9808037 | null | Shi-Hai Dong, Xi-wen Hou and Zhong-Qi Ma | Schr\"{o}dinger Equation with the Potential $V(r)=a r^2+b r^{-4}+c
r^{-6}$ | PS file 10 pages, Submitted to J.P.A | null | null | null | quant-ph | null | By making use of an ${\it ansatz}$ for the eigenfunction, we obtain the exact
solutions to the Schr\"{o}dinger equation with the anharmonic potential,
$V(r)=a r^2+b r^{-4}+c r^{-6}$, both in three dimensions and in two dimensions,
where the parameters $a$, $b$, and $c$ in the potential satisfy some
constraints.
| [
{
"version": "v1",
"created": "Fri, 21 Aug 1998 10:54:01 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Dong",
"Shi-Hai",
""
],
[
"Hou",
"Xi-wen",
""
],
[
"Ma",
"Zhong-Qi",
""
]
] |
quant-ph/9808038 | null | Shi-Hai Dong, Xi-Wen Hou and Zhong-Qi Ma | Levinson's Theorem for the Klein-Gordon Equation in Two Dimensions | Revtex file 14 pages, submitted to Phys. Rev. A | null | 10.1103/PhysRevA.59.995 | null | quant-ph | null | The two-dimensional Levinson theorem for the Klein-Gordon equation with a
cylindrically symmetric potential $V(r)$ is established. It is shown that
$N_{m}\pi=\pi (n_{m}^{+}-n_{m}^{-})=
[\delta_{m}(M)+\beta_{1}]-[\delta_{m}(-M)+\beta_{2}]$, where $N_{m}$ denotes
the difference between the number of bound states of the particle $n_{m}^{+}$
and the ones of antiparticle $n_{m}^{-}$ with a fixed angular momentum $m$, and
the $\delta_{m}$ is named phase shifts. The constants $\beta_{1}$ and
$\beta_{2}$ are introduced to symbol the critical cases where the half bound
states occur at $E=\pm M$.
| [
{
"version": "v1",
"created": "Fri, 21 Aug 1998 11:30:16 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Dong",
"Shi-Hai",
""
],
[
"Hou",
"Xi-Wen",
""
],
[
"Ma",
"Zhong-Qi",
""
]
] |
quant-ph/9808039 | Noah Linden | N Linden H Barjat R Freeman | An implementation of the Deutsch-Jozsa algorithm on a three-qubit NMR
quantum computer | 13 pages, 1 figure | null | null | null | quant-ph | null | A new approach to the implementation of a quantum computer by high-resolution
nuclear magnetic resonance (NMR) is described. The key feature is that two or
more line-selective radio-frequency pulses are applied simultaneously. A
three-qubit quantum computer has been investigated using the 400 MHz NMR
spectrum of the three coupled protons in 2,3-dibromopropanoic acid. It has been
employed to implement the Deutsch-Jozsa algorithm for distinguishing between
constant and balanced functions. The extension to systems containing more
coupled spins is straightforward and does not require a more protracted
experiment.
| [
{
"version": "v1",
"created": "Fri, 21 Aug 1998 15:50:55 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Freeman",
"N Linden H Barjat R",
""
]
] |
quant-ph/9808040 | Lev Vaidman | L. Vaidman, N. Yoran | Methods for Reliable Teleportation | 11 pages, 5eps figures | null | 10.1103/PhysRevA.59.116 | null | quant-ph | null | Recent experimental results and proposals towards implementation of quantum
teleportation are discussed. It is proved that reliable (theoretically, 100%
probability of success) teleportation cannot be achieved using the methods
applied in recent experiments, i.e., without quantum systems interacting one
with the other. Teleportation proposal involving atoms and electro-magnetic
cavities are reviewed and the most feasible methods are described. In
particular, the language of nonlocal measurements has been applied which has
also been used for presenting a method for teleportation of quantum states of
systems with continuous variables.
| [
{
"version": "v1",
"created": "Fri, 21 Aug 1998 16:08:04 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Vaidman",
"L.",
""
],
[
"Yoran",
"N.",
""
]
] |
quant-ph/9808041 | Marius | Marius Grigorescu and Mahi R. Singh (University of Western Ontario) | Quantum Coherence Oscillations in Antiferromagnetic Chains | 10 pages, Latex, two postscript figures; submitted to Phys. Rev. B | Phys.Rev.B59:6013,1999 | 10.1103/PhysRevB.59.6013 | null | quant-ph | null | Macroscopic quantum coherence oscillations in mesoscopic antiferromagnets may
appear when the anisotropy potential creates a barrier between the
antiferromagnetic states with opposite orientations of the Neel vector. This
phenomenon is studied for the physical situation of the nuclear spin system of
eight Xe atoms arranged on a magnetic surface along a chain. The oscillation
period is calculated as a function of the chain constant. The environmental
decoherence effects at finite temperature are accounted assuming a dipole
coupling between the spin chain and the fluctuating magnetic field of the
surface. The numerical calculations indicate that the oscillations are damped
by a rate $\sim (N-1)/ \tau$, where $N$ is the number of spins and $\tau$ is
the relaxation time of a single spin.
| [
{
"version": "v1",
"created": "Sat, 22 Aug 1998 01:07:12 GMT"
}
] | 2011-08-04T00:00:00 | [
[
"Grigorescu",
"Marius",
"",
"University of Western Ontario"
],
[
"Singh",
"Mahi R.",
"",
"University of Western Ontario"
]
] |
quant-ph/9808042 | Vladimir Buzek | V. Buzek, R. Derka, and S. Massar | Optimal Quantum Clocks | 4 pages, revtex, 1 figure, revision contains some new results | Phys.Rev.Lett. 82 (1999) 2207-2210 | 10.1103/PhysRevLett.82.2207 | null | quant-ph | null | A quantum clock must satisfy two basic constraints. The first is a bound on
the time resolution of the clock given by the difference between its maximum
and minimum energy eigenvalues. The second follows from Holevo's bound on how
much classical information can be encoded in a quantum system. We show that
asymptotically, as the dimension of the Hilbert space of the clock tends to
infinity, both constraints can be satisfied simultaneously. The experimental
realization of such an optimal quantum clock using trapped ions is discussed.
| [
{
"version": "v1",
"created": "Mon, 24 Aug 1998 08:48:37 GMT"
},
{
"version": "v2",
"created": "Tue, 1 Dec 1998 10:03:16 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Buzek",
"V.",
""
],
[
"Derka",
"R.",
""
],
[
"Massar",
"S.",
""
]
] |
quant-ph/9808043 | Pawel M. Masiak | Pawel Masiak and Peter L. Knight | Copying of entangled states and the degradation of correlations | 8 pages, RevTex, 6 EPS figures, submitted to Phys. Rev. A | Fortsch.Phys. 49 (2001) 1001-1009 | 10.1002/1521-3978(200110)49:10/11<1001::AID-PROP1001>3.0.CO;2-B | null | quant-ph | null | We investigate the degree to which entanglement survives when a correlated
pair of two-state systems are copied using either local or non-local processes.
We show how the copying process degrades the entanglement, due to a residual
correlation between the copied output and the copying machine (itself made of
qubits).
| [
{
"version": "v1",
"created": "Mon, 24 Aug 1998 15:52:07 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Masiak",
"Pawel",
""
],
[
"Knight",
"Peter L.",
""
]
] |
quant-ph/9808044 | Jochen Dittmann | J. Dittmann | Note on Explicit Formulae for the Bures Metric | 9 pages, LaTeX | J.Phys.A32:2663-2670,1999 | 10.1088/0305-4470/32/14/007 | null | quant-ph math-ph math.MP | null | The aim of this paper is to derive explicit formulae for the Riemannian Bures
metric on the manifold of (finite dimensional) nondegenerate density matrices.
The computation of the Bures metric using the presented equations does not
require any diagonalization procedure and uses matrix products, determinants
and traces, only.
| [
{
"version": "v1",
"created": "Mon, 24 Aug 1998 20:25:04 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Dittmann",
"J.",
""
]
] |
quant-ph/9808045 | Jeeva S. Anandan | Jeeva S. Anandan | Are There Dynamical Laws? | 35 pages, latex | Found.Phys. 29 (1999) 1647-1672 | null | null | quant-ph hep-th | null | The nature of a physical law is examined, and it is suggested that there may
not be any fundamental dynamical laws. This explains the intrinsic
indeterminism of quantum theory. The probabilities for transition from a given
initial state to a final state then depends on the quantum geometry that is
determined by symmetries, which may exist as relations between states in the
absence of dynamical laws. This enables the experimentally well confirmed
quantum probabilities to be derived from the geometry of Hilbert space, and
gives rise to effective probabilistic laws. An arrow of time which is
consistent with the one given by the second law of thermodynamics, regarded as
an effective law, is obtained. Symmetries are used as the basis for a new
proposed paradigm of physics. This gives rise naturally to the gravitational
and gauge fields from the symmetry group of the standard model, and a general
procedure for obtaining interactions from any symmetry group.
| [
{
"version": "v1",
"created": "Mon, 24 Aug 1998 22:45:55 GMT"
},
{
"version": "v2",
"created": "Sun, 30 Aug 1998 08:32:22 GMT"
},
{
"version": "v3",
"created": "Tue, 15 Sep 1998 18:03:45 GMT"
},
{
"version": "v4",
"created": "Thu, 12 Aug 1999 23:08:45 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Anandan",
"Jeeva S.",
""
]
] |
quant-ph/9808046 | S. V. Stepkin | S.S.Sannikov, A.A.Stanislavsky | Quantization of the Dirac Fibre: a New Way in the Particle Physics | RevTeX, 8 pages | null | null | null | quant-ph | null | The problem of ultraviolet divergences is analysed in the quantum field
theory. It was found that it has common roots with the problem of cosmological
singularity. In the context of fibre bundles the second quantization method is
represented as a procedure of the quantization for vector bundle cross-section.
It is shown to be quite a different quantization way called as a fibre
quantization which leads to an idea on existence of the non-standard dynamical
system, i.e. the relativistic be-Hamiltonian system. It takes place on
supersmall distances and is well described by the mathematical apparatus for
the non-unitary quantum scheme using a dual pair of topological vector spaces
in terms of the non-Hermitian form. The article contains the proof of the
theorem on radical changes in space and in matter structure taking place for a
very high density of matter: the phase transitions ``Lagrangian field system
(elementary particles) $\to$ relativistic bi-Hamiltonian system (Feynman's
partons)'' and ``continuum $\to$ discontinuum''.
All required calculations in the framework of the proposed theory are
published in the Russian periodicals. The purpose of this article is to replace
the calculations by reasonings and concepts. The present article begins the
systematic exposition of principles of the theory.
| [
{
"version": "v1",
"created": "Tue, 25 Aug 1998 07:57:16 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sannikov",
"S. S.",
""
],
[
"Stanislavsky",
"A. A.",
""
]
] |
quant-ph/9808047 | S. V. Stepkin | S.S.Sannikov, A.A.Stanislavsky | Non-Fock Representations of Heisenberg Algebras | LaTeX, 31 pages | null | null | null | quant-ph | null | The purpose of this paper is to present the mathematical techniques of a new
quantum scheme using a dual pair of reflexive topological vector spaces in
terms of the non-Hermitian form. The scheme is shown to be a generalization of
the well-known unitary quantum theory and to describe jointly quantum objects
and physical vacuum.
| [
{
"version": "v1",
"created": "Tue, 25 Aug 1998 11:14:00 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sannikov",
"S. S.",
""
],
[
"Stanislavsky",
"A. A.",
""
]
] |
quant-ph/9808048 | Mauro Fortunato | Mauro Fortunato (1 and 2), Gershon Kurizki (3), and Wolfgang P.
Schleich (1) ((1) University of Ulm, (2) University of Camerino, (3) The
Weizmann Institute of Science) | Stabilization of Deterministically Chaotic Systems by Interference and
Quantum Measurements: The Ikeda Map Case | RevTeX, 5 pages, two figures | Phys.Rev.Lett. 80 (1998) 5730 | 10.1103/PhysRevLett.80.5730 | null | quant-ph | null | We propose a method which can effectively stabilize fixed points in the
classical and quantum dynamics of a phase-sensitive chaotic system with
feedback. It is based on feeding back a selected quantum sub-ensemble whose
phase and amplitude stabilize the otherwise chaotic dynamics. Although the
method is rather general, we apply it to realizations of the inherently chaotic
Ikeda map. One suggested realization involves the Mach-Zender interferometer
with Kerr nonlinearity. Another realization involves a trapped ion interacting
with laser fields.
| [
{
"version": "v1",
"created": "Tue, 25 Aug 1998 11:28:49 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Fortunato",
"Mauro",
"",
"1 and 2"
],
[
"Kurizki",
"Gershon",
""
],
[
"Schleich",
"Wolfgang P.",
""
]
] |
quant-ph/9808049 | Mauro Fortunato | Mauro Fortunato (1 and 2), Gershon Kurizki (3), and Wolfgang P.
Schleich (1) ((1) University of Ulm, (2) University of Camerino, (3) The
Weizmann Institute of Science) | Trapping state restoration in the randomly-driven Jaynes-Cummings model
by conditional measurements | RevTeX, 5 pages, four (EPS) figures automatically included through
epsfig. Physical Review A 1998 (accepted for publication) Two references
added to Ref. [8]. No other change. Final version which will appear in
Physical Review A | Phys.Rev. A59 (1999) 714 | 10.1103/PhysRevA.59.714 | null | quant-ph | null | We propose a scheme which can effectively restore fixed points in the quantum
dynamics of repeated Jaynes-Cummings interactions followed by atomic state
measurements, when the interaction times fluctuate randomly. It is based on
selection of superposed atomic states whose phase correlations tend to suppress
the phase fluctuations of each separate state. One suggested realization
involves the convergence of the cavity field distribution to a single Fock
state by conditional measurements performed on two-level atoms with fluctuating
velocities after they cross the cavity. Another realization involves a trapped
ion whose internal-motional state coupling fluctuates randomly. Its motional
state is made to converge to a Fock state by conditional measurements of the
internal state of the ion.
| [
{
"version": "v1",
"created": "Tue, 25 Aug 1998 12:29:30 GMT"
},
{
"version": "v2",
"created": "Wed, 16 Sep 1998 02:21:45 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Fortunato",
"Mauro",
"",
"1 and 2"
],
[
"Kurizki",
"Gershon",
""
],
[
"Schleich",
"Wolfgang P.",
""
]
] |
quant-ph/9808050 | Volodymyr Tkachuk | V.M. Tkachuk | Supersymmetric Method for Constructing Quasi-Exactly and
Conditionally-Exactly Solvable Potentials | 17 pages, latex, no figures | J.Phys.A32:1291-1300,1999 | 10.1088/0305-4470/32/7/019 | null | quant-ph math-ph math.MP | null | Using supersymmetric quantum mechanics we develop a new method for
constructing quasi-exactly solvable (QES) potentials with two known
eigenstates. This method is extended for constructing conditionally-exactly
solvable potentials (CES). The considered QES potentials at certain values of
parameters become exactly solvable and can be treated as CES ones.
| [
{
"version": "v1",
"created": "Tue, 25 Aug 1998 15:10:21 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Tkachuk",
"V. M.",
""
]
] |
quant-ph/9808051 | Masanori Ohya | Masanori Ohya | A mathematical foundation of quantum information and quantum computer
-on quantum mutual entropy and entanglement- | 10 pages, Latex2e | null | null | null | quant-ph | null | The study of mutual entropy (information) and capacity in classica l system
was extensively done after Shannon by several authors like Kolmogor ov and
Gelfand. In quantum systems, there have been several definitions of t he mutual
entropy for classical input and quantum output. In 1983, the autho r defined
the fully quantum mechanical mutual entropy by means of the relati ve entropy
of Umegaki, and it has been used to compute the capacity of quant um channel
for quantum communication process; quantum input-quantum output.
Recently, a correlated state in quantum syatems, so-called quantum entangled
state or quantum entanglement, are used to study quntum information, in part
icular, quantum computation, quantum teleportation, quantum cryptography.
In this paper, we mainly discuss three things below: (1) We point out the di
fference between the capacity of quantum channel and that of classical-quant
um-classical channel. (2) So far the entangled state is merely defined as a
non-separable state, we give a wider definition of the entangled state and c
lassify the entangled states into three categories. (3) The quantum mutual e
ntropy for an entangled state is discussed. The above (2) and (3) are a join t
work with Belavkin.
| [
{
"version": "v1",
"created": "Wed, 26 Aug 1998 07:17:58 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ohya",
"Masanori",
""
]
] |
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