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quant-ph/9810096 | Li You | W.Geist, L.You and T.A.B.Kennedy | Sympathetic cooling of an atomic Bose-Fermi gas mixture | 8 pages, 9 figures, accepted for publication in Phys.Rev.Lett | null | 10.1103/PhysRevA.59.1500 | null | quant-ph cond-mat | null | Sympathetic cooling of an atomic Fermi gas by a Bose gas is studied by
solution of the coupled quantum Boltzmann equations for the confined gas
mixture. Results for equilibrium temperatures and relaxation dynamics are
presented, and some simple models developed. Our study illustrate that a
combination of sympathetic and forced evaporative cooling enables the Fermi gas
to be cooled to the degenerate regime where quantum statistics, and mean field
effects are important. The influence of mean field effects on the equilibrium
spatial distributions is discussed qualitatively.
| [
{
"version": "v1",
"created": "Fri, 30 Oct 1998 22:44:26 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Geist",
"W.",
""
],
[
"You",
"L.",
""
],
[
"Kennedy",
"T. A. B.",
""
]
] |
quant-ph/9811001 | Tien D. Kieu | Tien D. Kieu and Michael Danos | The halting problem for universal quantum computers | Latex, 5 A4 pages | null | null | C-98-60 | quant-ph | null | The halting of universal quantum computers is shown to be incompatible with
the constraint of unitarity of the dynamics.
| [
{
"version": "v1",
"created": "Mon, 2 Nov 1998 05:17:31 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kieu",
"Tien D.",
""
],
[
"Danos",
"Michael",
""
]
] |
quant-ph/9811002 | Laboratory of nanophysics | V. Filinov, Yu. Lozovik, A. Filinov, I. Zacharov, A. Oparin | Quantum dynamics in canonical and micro-canonical ensembles. Part II.
Tunneling in double well potential | 7 pages, 8 figures | Physica Scripta, 1998, Vol. 58, page 304 | 10.1088/0031-8949/58/4/004 | ISAN-98-02 | quant-ph cond-mat.stat-mech | null | In the second part of this paper in micro canonical ensemble the new
numerical approach for consideration of quantum dynamics and calculations of
the average values of quantum operators and time correlation functions in the
Wigner representation of quantum statistical mechanics has been developed. The
numerical results have been obtained for series of the average values of
quantum operators as well as for the time correlation function characterizing
the energy level structure, the momentum flow of tunneling particles at barrier
crossing and the absorption spectra of electron in potential well. The
developed quantum dynamics method was tested by comparison of numerical results
with analytical estimations. Tunneling transitions and the effect of the quasi
stationary state has been considered as the reason of the peculiarities in
behaviour of the time correlation functions and position and momentum
dispersions. Possibility of applying the developed approach to the theory of
classical wave propagation in random media have been also considered. For
classical waves some results have been obtained for Gaussian beam propagation
in 2D and 3D waveguides.
| [
{
"version": "v1",
"created": "Mon, 2 Nov 1998 15:26:23 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Nov 1998 07:53:18 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Filinov",
"V.",
""
],
[
"Lozovik",
"Yu.",
""
],
[
"Filinov",
"A.",
""
],
[
"Zacharov",
"I.",
""
],
[
"Oparin",
"A.",
""
]
] |
quant-ph/9811003 | Martin Plenio | M.B. Plenio, S.F. Huelga, A. Beige and P.L. Knight | Cavity Loss Induced Generation of Entangled Atoms | Replaced with the published version which contains, at the end of
Section V, a demonstration that the scheme can be extended to perfect
entangled state preparation at arbitrarily low detector efficiencies. All
other conclusions remain unchanged | Phys.Rev. A59 (1999) 2468-2475 | 10.1103/PhysRevA.59.2468 | null | quant-ph | null | We discuss the generation of entangled states of two two-level atoms inside
an optical resonator. When the cavity decay is continuously monitored, the
absence of photon-counts is associated with the presence of an atomic entangled
state. In addition to being conceptually simple, this scheme could be
demonstrated with presently available technology. We describe how such a state
is generated through conditional dynamics, using quantum jump methods,
including both cavity damping and spontaneous emission decay, and evaluate the
fidelity and relative entropy of entanglement of the generated state compared
with the target entangled state.
| [
{
"version": "v1",
"created": "Mon, 2 Nov 1998 14:43:13 GMT"
},
{
"version": "v2",
"created": "Tue, 11 Oct 2005 09:02:23 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Plenio",
"M. B.",
""
],
[
"Huelga",
"S. F.",
""
],
[
"Beige",
"A.",
""
],
[
"Knight",
"P. L.",
""
]
] |
quant-ph/9811004 | Michal Horodecki | Ryszard Horodecki, Michal Horodecki and Pawel Horodecki | Einstein-Podolsky-Rosen paradox without entanglement | RevTeX, 2 pages | null | 10.1103/PhysRevA.60.4144 | null | quant-ph | null | We claim that the nonlocality without entanglement revealed quite recently by
Bennett {\it et al.} [quant-ph/9804053] should be rather interpreted as {\it
Einstein-Podolsky-Rosen paradox without entanglement}. It would be true
nonlocality without entanglement if one knew that quantum mechnics provides the
best possible means for extracting information from physical system i.e. that
it is ``operationally complete''.
| [
{
"version": "v1",
"created": "Mon, 2 Nov 1998 20:33:19 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Horodecki",
"Ryszard",
""
],
[
"Horodecki",
"Michal",
""
],
[
"Horodecki",
"Pawel",
""
]
] |
quant-ph/9811005 | Subhash Kak | Subhash Kak | A Note on Quantum Errors and Their Correction | 9 pages | Found.Phys. 29 (1999) 267-279 | null | Report 98-5, LSU-ECE | quant-ph | null | This note presents a few observations on the nonlocal nature of quantum
errors and the expected performance of the recently proposed quantum
error-correction codes that are based on the assumption that the errors are
either bit-flip or phase-flip or both.
| [
{
"version": "v1",
"created": "Mon, 2 Nov 1998 21:56:51 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kak",
"Subhash",
""
]
] |
quant-ph/9811006 | Christof Zalka | Christof Zalka (T-6 LANL USA) | An Introduction to Quantum Computers | 8 pages, LaTeX | null | null | null | quant-ph hep-ph | null | This is a short introduction to quantum computers, quantum algorithms and
quantum error correcting codes. Familiarity with the principles of quantum
theory is assumed. Emphasis is put on a concise presentation of the principles
avoiding lengthy discussions.
| [
{
"version": "v1",
"created": "Tue, 3 Nov 1998 21:20:07 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Zalka",
"Christof",
"",
"T-6 LANL USA"
]
] |
quant-ph/9811007 | Michael Fleischhauer | M. Fleischhauer, R. Unanyan, B.W. Shore, and K. Bergmann | Coherent population transfer beyond the adiabatic limit: generalized
matched pulses and higher-order trapping states | 15 pages, 9 figures | null | 10.1103/PhysRevA.59.3751 | null | quant-ph | null | We show that the physical mechanism of population transfer in a 3-level
system with a closed loop of coherent couplings (loop-STIRAP) is not equivalent
to an adiabatic rotation of the dark-state of the Hamiltonian but coresponds to
a rotation of a higher-order trapping state in a generalized adiabatic basis.
The concept of generalized adiabatic basis sets is used as a constructive tool
to design pulse sequences for stimulated Raman adiabatic passage (STIRAP) which
give maximum population transfer also under conditions when the usual condition
of adiabaticty is only poorly fulfilled. Under certain conditions for the
pulses (generalized matched pulses) there exists a higher-order trapping state,
which is an exact constant of motion and analytic solutions for the atomic
dynamics can be derived.
| [
{
"version": "v1",
"created": "Tue, 3 Nov 1998 07:59:54 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Fleischhauer",
"M.",
""
],
[
"Unanyan",
"R.",
""
],
[
"Shore",
"B. W.",
""
],
[
"Bergmann",
"K.",
""
]
] |
quant-ph/9811008 | Richard L. Hall | Richard L. Hall and Nasser Saad | Eigenvalue bounds for a class of singular potentials in N dimensions | 10 pages (plain tex with 2 ps figures). J.Phys.A:Math.Gen.(In Press) | J.Phys.A32:133-138,1999 | 10.1088/0305-4470/32/1/014 | CUQM-72 | quant-ph math-ph math.MP | null | The eigenvalue bounds obtained earlier [J. Phys. A: Math. Gen. 31 (1998) 963]
for smooth transformations of the form V(x) = g(x^2) + f(1/x^2) are extended to
N-dimensions. In particular a simple formula is derived which bounds the
eigenvalues for the spiked harmonic oscillator potential V(x) = x^2 +
lambda/x^alpha, alpha > 0, lambda > 0, and is valid for all discrete
eigenvalues, arbitrary angular momentum ell, and spatial dimension N.
| [
{
"version": "v1",
"created": "Tue, 3 Nov 1998 14:30:44 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hall",
"Richard L.",
""
],
[
"Saad",
"Nasser",
""
]
] |
quant-ph/9811009 | Luis J. Garay | Inigo L. Egusquiza, Luis J. Garay, and Jose M. Raya | Quantum evolution according to real clocks | RevTeX 3.01, 6 pages | Phys.Rev. A59 (1999) 3236-3240 | 10.1103/PhysRevA.59.3236 | EHU-FT/9807 | quant-ph gr-qc | null | We characterize good clocks, which are naturally subject to fluctuations, in
statistical terms. We also obtain the master equation that governs the
evolution of quantum systems according to these clocks and find its general
solution. This master equation is diffusive and produces loss of coherence.
Moreover, real clocks can be described in terms of effective interactions that
are nonlocal in time. Alternatively, they can be modeled by an effective
thermal bath coupled to the system.
| [
{
"version": "v1",
"created": "Tue, 3 Nov 1998 18:05:36 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Egusquiza",
"Inigo L.",
""
],
[
"Garay",
"Luis J.",
""
],
[
"Raya",
"Jose M.",
""
]
] |
quant-ph/9811010 | Joachim Kupsch | Joachim Kupsch | Exactly soluble models of decoherence | 12 pages, Latex | null | null | null | quant-ph | null | Superselection rules induced by the interaction with the environment are a
basis to understand the emergence of classical observables within quantum
theory. The aim of this article is to investigate the decoherence effects,
which lead to superselection sectors, with the help of exactly soluble
Hamiltonian models. Starting from the examples of Araki and of Zurek more
general models with scattering are presented for which the projection operators
onto the induced superselection sectors do no longer commute with the
Hamiltonian. The example of an environment given by a free quantum field
indicates that infrared divergence plays an essential role for the emergence of
induced superselection sectors. For all models the induced superselection
sectors are uniquely determined by the Hamiltonian, whereas the time scale of
the decoherence depends crucially on the initial state of the total system.
| [
{
"version": "v1",
"created": "Wed, 4 Nov 1998 13:04:08 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kupsch",
"Joachim",
""
]
] |
quant-ph/9811011 | Jason Twamley | J. Steinbach (1) and J. Twamley (2) ((1) Imperial College London, (2)
National University of Ireland Maynooth) | Motional Quantum Error Correction | 24 Pages, RevTex, also see
http://www.thphys.may.ie/jtwamley/jtwamley.html Submitted to PRA. (CHANGED to
two-column style) | null | null | NUI-Maynooth-THPHYS-031198 | quant-ph | null | We examine the dynamics of a qubit stored in the motional degrees of freedom
of an ultra-cold ion in an ion trap which is subject to the decoherence effects
of a finite-temperature bath. We discover an encoding of the qubit, in two of
the motional modes of the ion, which is stable against the occurrence of either
none or one quantum jump. For the case of a zero-temperature bath we describe
how to transfer only the information concerning the occurrence of quantum jumps
and their types to a measuring apparatus, without affecting the ion's motional
state significantly. We then describe how to generate a unitary restoration of
the qubit given the jump information, through Raman processes generated by a
series of laser pulses.
| [
{
"version": "v1",
"created": "Wed, 4 Nov 1998 18:20:43 GMT"
},
{
"version": "v2",
"created": "Mon, 9 Nov 1998 14:00:57 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Steinbach",
"J.",
""
],
[
"Twamley",
"J.",
""
]
] |
quant-ph/9811012 | Anu Venugopalan | Anu Venugopalan, G. S. Agarwal | Superrevivals in the quantum dynamics of a particle confined in a finite
square well potential | 8 pages in Latex two-column format with 5 figures (eps). To appear in
Physical Review A | null | 10.1103/PhysRevA.59.1413 | null | quant-ph | null | We examine the revival features in wave packet dynamics of a particle
confined in a finite square well potential. The possibility of tunneling
modifies the revival pattern as compared to an infinite square well potential.
We study the dependence of the revival times on the depth of the square well
and predict the existence of superrevivals. The nature of these superrevivals
is compared with similar features seen in the dynamics of wavepackets in an
anharmonic oscillator potential.
| [
{
"version": "v1",
"created": "Thu, 5 Nov 1998 10:16:26 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Venugopalan",
"Anu",
""
],
[
"Agarwal",
"G. S.",
""
]
] |
quant-ph/9811013 | Marek Zukowski | Marek Zukowski | Violations of Local Realism in the Innsbruck GHZ Experiment | 1 eps figure, 4 pages | null | null | null | quant-ph | null | It is shown that a careful analysis of the `wrong' events (those not present
in the usual formulations of the GHZ argument), which are a necessary feature
of the tests of local realism involving independent sources, permits one to
show that there is no local realistic model, which is capable to describe
recent GHZ experiments performed in Innsbruck
| [
{
"version": "v1",
"created": "Thu, 5 Nov 1998 17:06:57 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Zukowski",
"Marek",
""
]
] |
quant-ph/9811014 | Ben C. Buchler | Ben C. Buchler, Malcolm B. Gray, Daniel A. Shaddock, Timothy C. Ralph,
David E. McClelland | Suppression of Classical and Quantum Radiation Pressure Noise via
Electro-Optic Feedback | 4 pages, 1 figure | null | 10.1364/OL.24.000259 | null | quant-ph physics.optics | null | We present theoretical results that demonstrate a new technique to be used to
improve the sensitivity of thermal noise measurements: intra-cavity intensity
stabilisation. It is demonstrated that electro-optic feedback can be used to
reduce intra-cavity intensity fluctuations, and the consequent radiation
pressure fluctuations, by a factor of two below the quantum noise limit. We
show that this is achievable in the presence of large classical intensity
fluctuations on the incident laser beam. The benefits of this scheme are a
consequence of the sub-Poissonian intensity statistics of the field inside a
feedback loop, and the quantum non-demolition nature of radiation pressure
noise as a readout system for the intra-cavity intensity fluctuations.
| [
{
"version": "v1",
"created": "Thu, 5 Nov 1998 23:24:46 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Nov 1998 05:04:23 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Buchler",
"Ben C.",
""
],
[
"Gray",
"Malcolm B.",
""
],
[
"Shaddock",
"Daniel A.",
""
],
[
"Ralph",
"Timothy C.",
""
],
[
"McClelland",
"David E.",
""
]
] |
quant-ph/9811015 | Ben C. Buchler | Ben C. Buchler, Elanor H. Huntington, Timothy C. Ralph | Noiseless phase quadrature amplification via electro-optic feed-forward | 8 pages, 4 figures | null | 10.1103/PhysRevA.60.529 | null | quant-ph physics.optics | null | Theoretical results are presented which show that noiseless phase quadrature
amplification is possible, and limited experimentally only by the efficiency of
the phase detection system. Experimental results obtained using a Nd:YAG laser
show a signal gain of 10dB and a signal transfer ratio of T_s=0.9. This result
easily exceeds the standard quantum limit for signal transfer. The results also
explicitly demonstrate the phase sensitive nature of the amplification process.
| [
{
"version": "v1",
"created": "Fri, 6 Nov 1998 00:26:12 GMT"
},
{
"version": "v2",
"created": "Thu, 17 Dec 1998 00:39:24 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Buchler",
"Ben C.",
""
],
[
"Huntington",
"Elanor H.",
""
],
[
"Ralph",
"Timothy C.",
""
]
] |
quant-ph/9811016 | Viktor V. Dodonov | E.C.Caparelli, V.V.Dodonov, S.S.Mizrahi (Univ. Federal de Sao Carlos,
Brazil) | Finite-Length Soliton Solutions of the Local Homogeneous Nonlinear
Schroedinger Equation | 11 pages, LaTex | Phys.Scripta 58 (1998) 417-420 | 10.1088/0031-8949/58/5/001 | null | quant-ph nlin.PS patt-sol | null | We found a new kind of soliton solutions for the 5-parameter family of the
potential-free Stenflo-Sabatier-Doebner-Goldin nonlinear modifications of the
Schr\"odinger equation. In contradistinction to the "usual'' solitons like
{\cosh[b(x-kt)]}^{-a}\exp[i(kx-ft)], the new {\em Finite-Length Solitons} (FLS)
are nonanalytical functions with continuous first derivatives, which are
different from zero only inside some finite regions of space. The simplest
one-dimensional example is the function which is equal to
{\cos[g(x-kt)]}^{1+d}\exp[i(kx-ft)] (with d>0) for |x-kt|<\pi/(2g), being
identically equal to zero for |x-kt|>\pi/(2g). The FLS exist even in the case
of a weak nonlinearity, whereas the ``usual'' solitons exist provided the
nonlinearity parameters surpass some critical values.
| [
{
"version": "v1",
"created": "Fri, 6 Nov 1998 11:35:05 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Caparelli",
"E. C.",
"",
"Univ. Federal de Sao Carlos,\n Brazil"
],
[
"Dodonov",
"V. V.",
"",
"Univ. Federal de Sao Carlos,\n Brazil"
],
[
"Mizrahi",
"S. S.",
"",
"Univ. Federal de Sao Carlos,\n Brazil"
]
] |
quant-ph/9811017 | Michael Fleischhauer | Michael Fleischhauer | Optical pumping in dense atomic media: Limitations due to reabsorption
of spontaneously emitted photons | 6 pages, 5 figures | Europhys.Lett. 45 (1999) 659-665 | 10.1209/epl/i1999-00218-2 | null | quant-ph | null | Resonant optical pumping in dense atomic media is discussed, where the
absorption length is less than the smallest characteristic dimension of the
sample. It is shown that reabsorption and multiple scattering of spontaneous
photons (radiation trapping) can substantially slow down the rate of optical
pumping. A very slow relaxation out of the target state of the pump process is
then sufficient to make optical pumping impossible. As model systems an
inhomogeneously and a radiatively broadened 3-level system resonantly driven
with a strong broad-band pump field are considered.
| [
{
"version": "v1",
"created": "Fri, 6 Nov 1998 17:46:29 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Fleischhauer",
"Michael",
""
]
] |
quant-ph/9811018 | Noah Linden | S.L. Braunstein, C.M. Caves, R. Jozsa, N. Linden, S. Popescu and R.
Schack | Separability of very noisy mixed states and implications for NMR quantum
computing | 4 pages, extensively revised, references added | Phys.Rev.Lett. 83 (1999) 1054-1057 | 10.1103/PhysRevLett.83.1054 | null | quant-ph | null | We give a constructive proof that all mixed states of N qubits in a
sufficiently small neighborhood of the maximally mixed state are separable. The
construction provides an explicit representation of any such state as a mixture
of product states. We give upper and lower bounds on the size of the
neighborhood, which show that its extent decreases exponentially with the
number of qubits. We also discuss the implications of the bounds for NMR
quantum computing.
| [
{
"version": "v1",
"created": "Fri, 6 Nov 1998 21:02:55 GMT"
},
{
"version": "v2",
"created": "Tue, 24 Nov 1998 17:53:08 GMT"
},
{
"version": "v3",
"created": "Fri, 18 Dec 1998 15:54:05 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Braunstein",
"S. L.",
""
],
[
"Caves",
"C. M.",
""
],
[
"Jozsa",
"R.",
""
],
[
"Linden",
"N.",
""
],
[
"Popescu",
"S.",
""
],
[
"Schack",
"R.",
""
]
] |
quant-ph/9811019 | Chiao | Raymond Y. Chiao | Tunneling Times and Superluminality: a Tutorial | 13 pages, Latex, 4 Figures | null | 10.1063/1.57888 | null | quant-ph | null | Experiments have shown that individual photons penetrate an optical tunnel
barrier with an effective group velocity considerably greater than the vacuum
speed of light. The experiments were conducted with a two-photon parametric
down-conversion light source, which produced correlated, but random, emissions
of photon pairs. The two photons of a given pair were emitted in slightly
different directions so that one photon passed through the tunnel barrier,
while the other photon passed through the vacuum. The time delay for the
tunneling photon relative to its twin was measured by adjusting the path length
difference between the two photons in a Hong-Ou-Mandel interferometer, in order
to achieve coincidence detection. We found that the photon transit time through
the barrier was smaller than the twin photon's transit time through an equal
distance in vacuum, indicating that the process of tunneling in quantum
mechanics is superluminal. Various conflicting theories of tunneling times are
compared with experiment.
| [
{
"version": "v1",
"created": "Sat, 7 Nov 1998 02:29:38 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Chiao",
"Raymond Y.",
""
]
] |
quant-ph/9811020 | Michael Nielsen | M. A. Nielsen, E. Knill, and R. Laflamme | Complete quantum teleportation using nuclear magnetic resonance | 15 pages, 2 figures. Minor differences between this and the published
version | Nature vol 395, 5 November 1998 | 10.1038/23891 | null | quant-ph | null | Quantum mechanics provides spectacular new information processing abilities
(Bennett 1995, Preskill 1998). One of the most unexpected is a procedure called
quantum teleportation (Bennett et al 1993) that allows the quantum state of a
system to be transported from one location to another, without moving through
the intervening space. Partial implementations of teleportation (Bouwmeester et
al 1997, Boschi et al 1998) over macroscopic distances have been achieved using
optical systems, but omit the final stage of the teleportation procedure. Here
we report an experimental implementation of the full quantum teleportation
operation over inter-atomic distances using liquid state nuclear magnetic
resonance (NMR). The inclusion of the final stage enables for the first time a
teleportation implementation which may be used as a subroutine in larger
quantum computations, or for quantum communication. Our experiment also
demonstrates the use of quantum process tomography, a procedure to completely
characterize the dynamics of a quantum system. Finally, we demonstrate a
controlled exploitation of decoherence as a tool to assist in the performance
of an experiment.
| [
{
"version": "v1",
"created": "Sun, 8 Nov 1998 22:44:19 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Nielsen",
"M. A.",
""
],
[
"Knill",
"E.",
""
],
[
"Laflamme",
"R.",
""
]
] |
quant-ph/9811021 | Maxim Olshanii | M. Olshanii, N. Dekker, C. Herzog, and M. Prentiss (Harvard
University) | de-Broglie Wave-Front Engineering | The figures' quality was improved, the text remains intact. 5 pages,
3 figures; submitted to PRL | Phys.Rev. A62 (2000) 033612 | 10.1103/PhysRevA.62.033612 | null | quant-ph cond-mat physics.atom-ph | null | We propose a simple method for the deterministic generation of an arbitrary
continuous quantum state of the center-of-mass of an atom. The method's spatial
resolution gradually increases with the interaction time with no apparent
fundamental limitations. Such de-Broglie Wave-Front Engineering of the atomic
density can find applications in Atom Lithography, and we discuss possible
implementations of our scheme in atomic beam experiments.
| [
{
"version": "v1",
"created": "Tue, 10 Nov 1998 00:05:49 GMT"
},
{
"version": "v2",
"created": "Tue, 10 Nov 1998 20:48:42 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Olshanii",
"M.",
"",
"Harvard\n University"
],
[
"Dekker",
"N.",
"",
"Harvard\n University"
],
[
"Herzog",
"C.",
"",
"Harvard\n University"
],
[
"Prentiss",
"M.",
"",
"Harvard\n University"
]
] |
quant-ph/9811022 | Erika Andersson | Erika Andersson, Marcia T. Fontenelle, Stig Stenholm | Quantum statistics of atoms in microstructures | 18 pages incl. 13 figures | null | 10.1103/PhysRevA.59.3841 | null | quant-ph | null | This paper proposes groove-like potential structures for the observation of
quantum information processing by trapped particles. As an illustration the
effect of quantum statistics at a 50-50 beam splitter is investigated. For
non-interacting particles we regain the results known from photon experiments,
but we have found that particle interactions destroy the perfect bosonic
correlations. Fermions avoid each other due to the exclusion principle and
hence they are far less sensitive to particle interactions. For bosons, the
behavior can be explained with simple analytic considerations which predict a
certain amount of universality. This is verified by detailed numerical
calculations.
| [
{
"version": "v1",
"created": "Mon, 9 Nov 1998 14:50:01 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Andersson",
"Erika",
""
],
[
"Fontenelle",
"Marcia T.",
""
],
[
"Stenholm",
"Stig",
""
]
] |
quant-ph/9811023 | Georg Junker | Akira Inomata (SUNY Albany), Georg Junker (Univ. Erlangen-Nuernberg) | A History of Feynman's Sum over Histories in Quantum Mechanics | 3 pages, to appear in the proceedings of the 6th International
Conference on "Path-Integrals from peV to TeV", Florence, Italy, 1998 | in R. Casalbuoni, R.Giachetti, V.Tognetti, R. Vaia, P.Verrucchi,
eds. "Path Integrals from peV to TeV: 50 years after Feynman's paper", (World
Scientific, Singapore, 1999) pp.19-21 | null | null | quant-ph hep-th math-ph math.MP physics.hist-ph | null | A history of Feynman's sum over histories is presented in brief. A focus is
placed on the progress of path-integration techniques for exactly
path-integrable problems in quantum mechanics.
| [
{
"version": "v1",
"created": "Tue, 10 Nov 1998 09:08:28 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Inomata",
"Akira",
"",
"SUNY Albany"
],
[
"Junker",
"Georg",
"",
"Univ. Erlangen-Nuernberg"
]
] |
quant-ph/9811024 | Je-Young Choi | Je-Young Choi and Seok-In Hong | Supersymmetric quantum mechanics with nonlocal potentials | 4 pages, REVTeX, Minor revisions for clarification | Phys.Rev. A60 (1999) 796 | 10.1103/PhysRevA.60.796 | null | quant-ph | null | We consider supersymmetric quantum mechanical models with both local and
nonlocal potentials. We present a nonlocal deformation of exactly solvable
local models. Its energy eigenfunctions and eigenvalues are determined exactly.
We observe that both our model Hamiltonian and its supersymmetric partner may
have normalizable zero-energy ground states, in contrast to local models with
nonperiodic or periodic potentials.
| [
{
"version": "v1",
"created": "Tue, 10 Nov 1998 11:52:34 GMT"
},
{
"version": "v2",
"created": "Mon, 1 Feb 1999 08:04:48 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Choi",
"Je-Young",
""
],
[
"Hong",
"Seok-In",
""
]
] |
quant-ph/9811025 | Stefan Keppeler | Jens Bolte and Stefan Keppeler | A semiclassical approach to the Dirac equation | null | Annals Phys. 274 (1999) 125-162 | 10.1006/aphy.1999.5912 | ULM-TP/98-6 | quant-ph chao-dyn math-ph math.MP nlin.CD | null | We derive a semiclassical time evolution kernel and a trace formula for the
Dirac equation. The classical trajectories that enter the expressions are
determined by the dynamics of relativistic point particles. We carefully
investigate the transport of the spin degrees of freedom along the trajectories
which can be understood geometrically as parallel transport in a vector bundle
with SU(2) holonomy. Furthermore, we give an interpretation in terms of a
classical spin vector that is transported along the trajectories and whose
dynamics, dictated by the equation of Thomas precession, gives rise to
dynamical and geometric phases every orbit is weighted by. We also present an
analogous approach to the Pauli equation which we analyse in two different
limits.
| [
{
"version": "v1",
"created": "Thu, 12 Nov 1998 13:22:23 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Bolte",
"Jens",
""
],
[
"Keppeler",
"Stefan",
""
]
] |
quant-ph/9811026 | Juan Pablo Paz | Juan Pablo Paz and Wojciech Hubert Zurek | Quantum limit of decoherence: Environment induced superselection of
energy eigenstates | 4 pages, no figures | Phys.Rev.Lett.82:5181-5185,1999 | 10.1103/PhysRevLett.82.5181 | null | quant-ph | null | We investigate decoherence in the limit where the interaction with the
environment is weak and the evolution is dominated by the self Hamiltonian of
the system. We show that in this case quantized eigenstates of energy emerge as
pointer states selected through the predictability sieve.
| [
{
"version": "v1",
"created": "Thu, 12 Nov 1998 14:52:03 GMT"
}
] | 2011-08-04T00:00:00 | [
[
"Paz",
"Juan Pablo",
""
],
[
"Zurek",
"Wojciech Hubert",
""
]
] |
quant-ph/9811027 | M. Trucks | C. Witte and M. Trucks | A new entanglement measure induced by the Hilbert-Schmidt norm | 12 pages, 1 figure, uses elsart.cls | Phys.Lett. A257 (1999) 14-20 | 10.1016/S0375-9601(99)00279-0 | null | quant-ph | null | In this letter we discuss a new entanglement measure. It is based on the
Hilbert-Schmidt norm of operators. We give an explicit formula for calculating
the entanglement of a large set of states on C^2 \times C^2. Furthermore we
find some relations between the entanglement of relative entropy and the
Hilbert-Schmidt entanglement. A rigorous definition of partial transposition is
given in the appendix.
| [
{
"version": "v1",
"created": "Thu, 12 Nov 1998 23:00:34 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Witte",
"C.",
""
],
[
"Trucks",
"M.",
""
]
] |
quant-ph/9811028 | Mikhail Lukin | M.D.Lukin, A.B.Matsko, M. Fleischhauer, and M.O.Scully | Quantum noise and correlations in resonantly enhanced wave mixing based
on atomic coherence | 4 pages, 1 figure | Phys.Rev.Lett. 82 (1999) 1847-1850 | 10.1103/PhysRevLett.82.1847 | null | quant-ph | null | We investigate the quantum properties of fields generated by resonantly
enhanced wave mixing based on atomic coherence in Raman systems. We show that
such a process can be used for generation of pairs of Stokes and anti-Stokes
fields with nearly perfect quantum correlations, yielding almost complete (i.e.
100%) squeezing without the use of a cavity.
We discuss the extension of the wave mixing interactions into the domain of a
few interacting light quanta.
| [
{
"version": "v1",
"created": "Fri, 13 Nov 1998 00:16:43 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Lukin",
"M. D.",
""
],
[
"Matsko",
"A. B.",
""
],
[
"Fleischhauer",
"M.",
""
],
[
"Scully",
"M. O.",
""
]
] |
quant-ph/9811029 | Akira Shimizu | Akira Shimizu and Jun-ichi Inoue (Department of Basic Science,
University of Tokyo, Komaba) | Time evolution of condensed state of interacting bosons with reduced
number fluctuation in a leaky box | 25 pages including 3 figures. To appear in Phys. Rev. A (1999). The
title is changed to stress the time evolution. Sections II, III and IV of the
previous manuscript have been combined into one section. The introduction and
summary of the previous manuscript have been combined into the Introduction
and Summary. The names and abbreviations of quantum states are changed to
stress that they are for interacting many bosons. More references are cited | null | 10.1103/PhysRevA.60.3204 | null | quant-ph cond-mat.stat-mech | null | We study the time evolution of the Bose-Einstein condensate of interacting
bosons confined in a leaky box, when its number fluctuation is initially (t=0)
suppressed. We take account of quantum fluctuations of all modes, including k =
0. We identify a ``natural coordinate'' b_0 of the interacting bosons, by which
many physical properties can be simply described. Using b_0, we successfully
define the cosine and sine operators for interacting many bosons. The
wavefunction, which we call the ``number state of interacting bosons'' (NSIB),
of the ground state that has a definite number N of interacting bosons can be
represented simply as a number state of b_0. We evaluate the time evolution of
the reduced density operator \rho(t) of the bosons in the box with a finite
leakage flux J, in the early time stage for which Jt << N. It is shown that
\rho(t) evolves from a single NSIB at t = 0, into a classical mixture of NSIBs
of various values of N at t > 0. We define a new state called the
``number-phase squeezed state of interacting bosons'' (NPIB). It is shown that
\rho(t) for t>0 can be rewritten as the phase-randomized mixture (PRM) of
NPIBs. It is also shown that the off-diagonal long-range order (ODLRO) and the
order parameter defined by it do not distinguish the NSIB and NPIB. On the
other hand, the other order parameter \Psi, defined as the expectation value of
the boson operator, has different values among these states. For each element
of the PRM of NPIBs, we show that \Psi evolves from zero to a finite value very
quickly. Namely, after the leakage of only two or three bosons, each element
acquires a full, stable and definite (non-fluctuating) value of \Psi.
| [
{
"version": "v1",
"created": "Fri, 13 Nov 1998 05:38:17 GMT"
},
{
"version": "v2",
"created": "Wed, 14 Jul 1999 07:42:41 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Shimizu",
"Akira",
"",
"Department of Basic Science,\n University of Tokyo, Komaba"
],
[
"Inoue",
"Jun-ichi",
"",
"Department of Basic Science,\n University of Tokyo, Komaba"
]
] |
quant-ph/9811030 | Milos V. Lokajicek | Milos V. Lokajicek | Realistic theory of microscopic phenomena; a new solution of
hidden-variable problem | null | null | null | PRA-HEP-98/8 | quant-ph | null | It has been shown that quantum paradoxes have followed from one special
assumption, i.e., from attributing basic physical meaning to Hamiltonian
eigenfunctions and representing all physical states by vectors of the Hilbert
space spanned on these eigenfunctions. However, any paradoxical properties
disappear if the physical states are represented by vectors from the extended
Hilbert space on which the scattering theory of Lax and Phillips has been
based. On the other side, all stationary characteristics and experimentally
verified quantum-mechanical predictions remain the same. The extended
mathematical model is also in full agreement with results of EPR experiments,
if one takes into account that a further assumption (in addition to locality
condition) is involved in derivation of Bell's inequalities as shown recently
(see: quant-ph/9808005).
| [
{
"version": "v1",
"created": "Fri, 13 Nov 1998 08:38:25 GMT"
},
{
"version": "v2",
"created": "Wed, 14 Jul 1999 07:09:22 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Lokajicek",
"Milos V.",
""
]
] |
quant-ph/9811031 | Viktor V. Dodonov | V. V. Dodonov and S. S. Mizrahi (Univ. Federal de Sao Carlos, Brazil) | Stationary States in Saturated Two-Photon Processes and Generation of
Phase-Averaged Mixtures of Even and Odd Quantum States | 8 pages, LaTex, 3 eps figures | Acta Phys.Slov. 48 (1998) 349-360 | null | null | quant-ph | null | We consider a relaxation of a single mode of the quantized field in a
presence of one- and two-photon absorption and emission processes. Exact
stationary solutions of the master equation for the diagonal elements of the
density matrix in the Fock basis are found in the case of completely saturated
two-photon emission. If two-photon processes dominate over single-photon ones,
the stationary state is a mixture of phase averaged even and odd coherent
states.
| [
{
"version": "v1",
"created": "Fri, 13 Nov 1998 13:40:25 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Dodonov",
"V. V.",
"",
"Univ. Federal de Sao Carlos, Brazil"
],
[
"Mizrahi",
"S. S.",
"",
"Univ. Federal de Sao Carlos, Brazil"
]
] |
quant-ph/9811032 | Bg Sidharth | B.G. Sidharth | The Symmetry Underlying Spin and the Dirac Equation | 6 pages, TeX, Paper at the Spin and Perturbation Theory 98,
symposium, Rome, 1998 | null | null | null | quant-ph gr-qc hep-th | null | It is shown, in the context of a recent formulation of elementary particles
in terms of, what may be called, a Quantum Mechanical Kerr-Newman metric, that
spin is a consequence of a space-time cut off at the Compton wavelength and
Compton time scale. On this basis, we deduce the Dirac equation from a simple
coordinate transformation.
| [
{
"version": "v1",
"created": "Sat, 14 Nov 1998 09:08:54 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sidharth",
"B. G.",
""
]
] |
quant-ph/9811033 | Luis Santos | Luis Santos and Luis Roso | Bloch-Like Quantum Multiple Reflections of Atoms | LaTeX, 7 pages, 7 figures | null | 10.1103/PhysRevA.60.2312 | null | quant-ph | null | We show that under certain circumstances an atom can follow an oscillatory
motion in a periodic laser profile with a Gaussian envelope. These oscillations
can be well explained by using a model of energetically forbidden spatial
regions. The similarities and differences with Bloch oscillations are
discussed. We demonstrate that the effect exists not only for repulsive but
also for attractive potentials, i.e. quantum multiple reflections are also
possible.
| [
{
"version": "v1",
"created": "Sat, 14 Nov 1998 11:48:49 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Santos",
"Luis",
""
],
[
"Roso",
"Luis",
""
]
] |
quant-ph/9811034 | Dieter Robaschik | H. Mitter, D. Robaschik | Thermodynamics of the Casimir Effect - Asymptotic Considerations - | Talk at the conference "Quantum Field Theory under the Influence of
External Conditions " Leipzig, 14.-18.9.1998, submitted to the conference
proceedings | null | null | UNIGRAZ-UTP 14-11-98 | quant-ph | null | We study the Casimir effect with different temperatures between the plates
($T$) resp. outside of them ($T'$). If we consider the inner system as the
black body radiation for a special geometry, then contrary to common belief the
temperature approaches a constant value for vanishing volume during isentropic
processes. This means: the reduction of the degrees of freedom can not be
compensated by a concentration of the energy during an adiabatic contraction of
the two-plate system. Looking at the Casimir pressure, we find one unstable
equilibrium point for isothermal processes with $T > T'$. For isentropic
processes there is additionally one stable equilibrium point for larger values
of the distances between the two plates.}
| [
{
"version": "v1",
"created": "Sat, 14 Nov 1998 16:35:47 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mitter",
"H.",
""
],
[
"Robaschik",
"D.",
""
]
] |
quant-ph/9811035 | Oliver Zobay | G. J. Yang, O. Zobay, and P. Meystre | Two-atom dark states in electromagnetic cavities | 8 pages, 4 figures | null | 10.1103/PhysRevA.59.4012 | null | quant-ph | null | The center-of-mass motion of two two-level atoms coupled to a single damped
mode of an electromagnetic resonator is investigated. For the case of one atom
being initially excited and the cavity mode in the vacuum state it is shown
that the atomic time evolution is dominated by the appearance of dark states.
These states, in which the initial excitation is stored in the internal atomic
degrees of freedom and the atoms become quantum mechanically entangled, are
almost immune against photon loss from the cavity. Various properties of the
dark states within and beyond the Raman-Nath approximation of atom optics are
worked out.
| [
{
"version": "v1",
"created": "Sat, 14 Nov 1998 23:51:58 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Yang",
"G. J.",
""
],
[
"Zobay",
"O.",
""
],
[
"Meystre",
"P.",
""
]
] |
quant-ph/9811036 | Terno Daniel | Daniel R. Terno | Non-linear operations in quantum information theory | 11 pages, LaTeX, 3 figures on separate pages | Phys.Rev. A59 (1999) 3320 | 10.1103/PhysRevA.59.3320 | null | quant-ph | null | Quantum information theory is used to analize various non-linear operations
on quantum states. The universal disentanglement machine is shown to be
impossible, and partial (negative) results are obtained in the state-dependent
case. The efficiency of the transformation of non-orthogonal states into
orthogonal ones is discussed.
| [
{
"version": "v1",
"created": "Sun, 15 Nov 1998 10:36:04 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Terno",
"Daniel R.",
""
]
] |
quant-ph/9811037 | Marco Frasca | Marco Frasca | Theory of dressed states in quantum optics | Revtex, 17 pages | Phys.Rev. A60 (1999) 573-581 | 10.1103/PhysRevA.60.573 | null | quant-ph hep-th physics.atom-ph | null | The dual Dyson series [M.Frasca, Phys. Rev. A {\bf 58}, 3439 (1998)], is used
to develop a general perturbative method for the study of atom-field
interaction in quantum optics. In fact, both Dyson series and its dual, through
renormalization group methods to remove secular terms from the perturbation
series, give the opportunity of a full study of the solution of the
Schr\"{o}dinger equation in different ranges of the parameters of the given
hamiltonian. In view of recent experiments with strong laser fields, this
approach seems well-suited to give a clarification and an improvement of the
applications of the dressed states as currently done through the eigenstates of
the atom-field interaction, showing that these are just the leading order of
the dual Dyson series when the Hamiltonian is expressed in the interaction
picture. In order to exploit the method at the best, a study is accomplished of
the well-known Jaynes-Cummings model in the rotating wave approximation, whose
exact solution is known, comparing the perturbative solutions obtained by the
Dyson series and its dual with the same approximations obtained by Taylor
expanding the exact solution. Finally, a full perturbative study of high-order
harmonic generation is given obtaining, through analytical expressions, a clear
account of the power spectrum using a two-level model, even if the method can
be successfully applied to a more general model that can account for ionization
too. The analysis shows that to account for the power spectrum it is needed to
go to first order in the perturbative analysis. The spectrum obtained gives a
way to measure experimentally the shift of the energy levels of the atom
interacting with the laser field by looking at the shifting of hyper-Raman
lines.
| [
{
"version": "v1",
"created": "Sun, 15 Nov 1998 21:35:05 GMT"
},
{
"version": "v2",
"created": "Wed, 7 Jul 1999 16:02:05 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Frasca",
"Marco",
""
]
] |
quant-ph/9811038 | Molotkov S. | S.N.Molotkov (Institute of Solid State Physics, Russian Academy of
Sciences) | Quantum cryptography based on photon ``frequency'' states: example of a
possible realization | 10 pages, 1 figure | null | 10.1134/1.558658 | null | quant-ph | null | A quantum cryptosystem is proposed using single-photon states with different
frequency spectra as information carriers. A possible experimental
implementation of the cryptosystem is discussed.
| [
{
"version": "v1",
"created": "Mon, 16 Nov 1998 14:22:34 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Molotkov",
"S. N.",
"",
"Institute of Solid State Physics, Russian Academy of\n Sciences"
]
] |
quant-ph/9811039 | Castagnoli Giuseppe | Giuseppe Castagnoli and Dalida Monti (Information Technology Dept.,
Genova, Italy) | The Non-mechanistic Character of Quantum Computation | revision 4: further developed the notion that quantum efficiency
comes from driving the computation process through a final condition; various
clarifications after receiving comments; reduced the number of figures; 10
text pages (1 file), 2 figures (1 additional file); submitted for the
Proceedings of the International Quantum Structures Association Conference,
Liptovsky Jan, September 1998 | null | null | null | quant-ph | null | The higher than classical efficiency exhibited by some quantum algorithms is
here ascribed to their non-mechanistic character, which becomes evident by
joining the notions of entanglement and quantum measurement. Measurement
analogically sets a (partial) constraint on the output of the computation of a
hard-to-reverse function. This constraint goes back in time along the
reversible computation process, computing the reverse function, which yields
quantum efficiency. The evolution, comprising wave function collapse (here a
revamped notion), is non-mechanistic as it is driven by both an initial
condition and a final constraint. It seems that the more the output is
constrained by measurement, the higher can be the efficiency. Setting a
complete constraint, by means of a special Zeno effect, yields (speculatively)
NP-complete=P.
| [
{
"version": "v1",
"created": "Mon, 16 Nov 1998 16:23:40 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Nov 1998 09:56:13 GMT"
},
{
"version": "v3",
"created": "Thu, 3 Dec 1998 16:25:49 GMT"
},
{
"version": "v4",
"created": "Wed, 13 Jan 1999 16:07:48 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Castagnoli",
"Giuseppe",
"",
"Information Technology Dept.,\n Genova, Italy"
],
[
"Monti",
"Dalida",
"",
"Information Technology Dept.,\n Genova, Italy"
]
] |
quant-ph/9811040 | Guido Bacciagaluppi | Guido Bacciagaluppi (Oxford University) | Nelsonian Mechanics Revisited | LaTeX, 19 pp., submitted to Foundations of Physics | Found.Phys.Lett. 12 (1999) 1-16 | 10.1023/A:1021622603864 | null | quant-ph | null | In de Broglie and Bohm's pilot-wave theory, as is well known, it is possible
to consider alternative particle dynamics while still preserving the quantum
distribution. I present the analogous result for Nelson's stochastic theory,
thus characterising the most general diffusion processes that preserve the
quantum equilibrium distribution, and discuss the analogy with the construction
of the dynamics for Bell's beable theories. I briefly comment on the problem of
convergence to the quantum distribution and on possible experimental
constraints on the alternative dynamics.
| [
{
"version": "v1",
"created": "Mon, 16 Nov 1998 22:07:11 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Bacciagaluppi",
"Guido",
"",
"Oxford University"
]
] |
quant-ph/9811041 | Shasanka Mohan Roy | S.M. Roy (Tata Institute of Fundamental Research) and Virendra Singh
(Tata Institute of Fundamental Research) | Maximally Realistic Causal Quantum Mechanics | Published version | Phys.Lett. A255 (1999) 201-208 | 10.1016/S0375-9601(99)00186-3 | TIFR/TH/98-42, SU-4240-687 | quant-ph gr-qc hep-th | null | We recently constructed a causal quantum mechanics in 2 dim. phase space
which is more realistic than the de Broglie-Bohm mechanics as it reproduces not
just the position but also the momentum probability density of ordinary quantum
theory. Here we present an even more ambitious construction in 2n dim. phase
space. We conjecture that the causal Hamiltonian quantum mechanics presented
here is `maximally realistic'. The positive definite phase space density
reproduces as marginals the correct quantum probability densities of $n+1$
different complete commuting sets of observables (e.g. $\vec q$, $\vec p$ and
$n-1$ other sets). In general the particle velocities do not coincide with the
de Broglie-Bohm velocities.
| [
{
"version": "v1",
"created": "Tue, 17 Nov 1998 12:47:46 GMT"
},
{
"version": "v2",
"created": "Fri, 8 Oct 1999 08:34:08 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Roy",
"S. M.",
"",
"Tata Institute of Fundamental Research"
],
[
"Singh",
"Virendra",
"",
"Tata Institute of Fundamental Research"
]
] |
quant-ph/9811042 | null | Arthur Jabs | Comment on testing Bell's inequality with Rydberg atoms entangled
through cavity photons | Plain TeX, 10 pages, 2 figures | null | null | UFPB-DF-98/47 | quant-ph | null | Rydberg atoms traversing a micromaser cavity one after the other can emerge
in correlated states, and according to Copenhagen quantum mechanics this may
lead to a violation of Bell's inequality, that is, to a Bell sum S>2. S is here
calculated in various ideal physical situations including those with (1)
different initial states of the atoms, (2) different free adjustable
parameters, being either the phase or the turning angle of a classical
radiation field put behind the cavity, and (3) either equal or different Rabi
angles for successive atoms. The experiments are crucial for a realist
interpretation which predicts S<2 or S=2 because particles of different kinds
(photons and atoms) are involved.
| [
{
"version": "v1",
"created": "Tue, 17 Nov 1998 16:58:05 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Jabs",
"Arthur",
""
]
] |
quant-ph/9811043 | Noah Linden | N Linden, H Barjat, RJ Carbajo and R Freeman | Pulse Sequences for NMR Quantum Computers: How to Manipulate Nuclear
Spins While Freezing the Motion of Coupled Neighbours | 11 pages, 5 figs | null | 10.1016/S0009-2614(99)00339-5 | null | quant-ph | null | We show how to divide a coupled multi-spin system into a small subset of
``active'' spins that evolve under chemical shift or scalar coupling operators,
and a larger subset of ``spectator'' spins which are returned to their initial
states, as if their motion had been temporarily frozen. This allows us to
implement basic one-qubit and two-qubit operations from which general
operations on $N$-qubits can be constructed, suitable for quantum computation.
The principles are illustrated by experiments on the three coupled protons of
2,3-dibromopropanoic acid, but the method is applicable to any spin-1/2 nuclei
and to systems containing arbitrary numbers of coupled spins.
| [
{
"version": "v1",
"created": "Tue, 17 Nov 1998 17:45:42 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Linden",
"N",
""
],
[
"Barjat",
"H",
""
],
[
"Carbajo",
"RJ",
""
],
[
"Freeman",
"R",
""
]
] |
quant-ph/9811044 | Zengxz | Jun Luo and Xizhi Zeng (Wuhan Institute of Physics and Mathematics,
Chinese Academy of Sciences, Wuhan, People's Republic of China) | NMR Quantum Computation with a hyperpolarized nuclear spin bulk | 15 pages, LaTex, 2 PostScript figures on separated pages. Welcome to
Comments | null | null | null | quant-ph | null | We consider two new quantum gate mechanisms based on nuclear spins in
hyperpolarized solid $^{129}Xe$ and HCl mixtures and inorganic semiconductors.
We propose two schemes for implementing a controlled NOT (CNOT) gate based on
nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging
(MRI) from hyperpolarized solid $^{129}Xe$ and HCl mixtures and optically
pumped NMR in semiconductors. Such gates might be built up with particular
spins addressable based on MRI techniques and optical pumping and optical
detection techniques. The schemes could be useful for implementing actual
quantum computers in terms of a cellular automata architecture.
| [
{
"version": "v1",
"created": "Wed, 18 Nov 1998 13:34:37 GMT"
},
{
"version": "v2",
"created": "Thu, 19 Nov 1998 07:52:21 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Luo",
"Jun",
"",
"Wuhan Institute of Physics and Mathematics,\n Chinese Academy of Sciences, Wuhan, People's Republic of China"
],
[
"Zeng",
"Xizhi",
"",
"Wuhan Institute of Physics and Mathematics,\n Chinese Academy of Sciences, Wuhan, People's Republic of China"
]
] |
quant-ph/9811045 | Bg Sidharth | B.G. Sidharth | Quantum, Chaos and the Universe | 8 pages, TeX | null | null | null | quant-ph gr-qc hep-th | null | In this paper we suggest a formulation that would bear out the spirit of
Prigogine's "Order Out of Chaos" and Wheeler's "Law Without Law". In it a
typical elementary particle length, namely the pion Compton wavelength arises
from the random motion of the N particles in the universe of dimension R. It is
then argued in the light of recent work that this is the origin of the laws of
physics and leads to a cosmology consistent with observation.
| [
{
"version": "v1",
"created": "Wed, 18 Nov 1998 11:15:42 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sidharth",
"B. G.",
""
]
] |
quant-ph/9811046 | Ronald de Wolf | Harry Buhrman (CWI) and Ronald de Wolf (CWI and U Amsterdam) | Lower Bounds for Quantum Search and Derandomization | 12 pages LaTeX. Submitted to CCC'99 (formerly Structures) | null | null | null | quant-ph cs.CC | null | We prove lower bounds on the error probability of a quantum algorithm for
searching through an unordered list of N items, as a function of the number T
of queries it makes. In particular, if T=O(sqrt{N}) then the error is lower
bounded by a constant. If we want error <1/2^N then we need T=Omega(N) queries.
We apply this to show that a quantum computer cannot do much better than a
classical computer when amplifying the success probability of an RP-machine. A
classical computer can achieve error <=1/2^k using k applications of the
RP-machine, a quantum computer still needs at least ck applications for this
(when treating the machine as a black-box), where c>0 is a constant independent
of k. Furthermore, we prove a lower bound of Omega(sqrt{log N}/loglog N)
queries for quantum bounded-error search of an ordered list of N items.
| [
{
"version": "v1",
"created": "Wed, 18 Nov 1998 11:49:46 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Buhrman",
"Harry",
"",
"CWI"
],
[
"de Wolf",
"Ronald",
"",
"CWI and U Amsterdam"
]
] |
quant-ph/9811047 | Shasanka Mohan Roy | S.M.Roy (Tata Institute of Fundamental Research) | Maximally Causal Quantum Mechanics | 7 pages,latex,no figures,to appear in Pramana | Pramana 51 (1998) 597-602 | 10.1007/BF02827451 | TIFR/TH/98-45 | quant-ph | null | We present a new causal quantum mechanics in one and two dimensions developed
recently at TIFR by this author and V. Singh. In this theory both position and
momentum for a system point have Hamiltonian evolution in such a way that the
ensemble of system points leads to position and momentum probability densities
agreeing exactly with ordinary quantum mechanics.
| [
{
"version": "v1",
"created": "Wed, 18 Nov 1998 12:42:56 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Roy",
"S. M.",
"",
"Tata Institute of Fundamental Research"
]
] |
quant-ph/9811048 | Lutz Polley | Lutz Polley (Oldenburg University, Germany) | Schroedinger equation as the universal continuum limit of
nonrelativistic coherent hopping on a cubic spatial lattice | 6 pages, LaTeX; Introduction extended with reference to quantum
lattice-gas models | null | null | null | quant-ph | null | The Schroedinger equation with scalar and vector potentials is the continuum
limit of any coherent hopping process (where position eigenstates superpose
with neighbouring eigenstates after a time step) whose hopping amplitudes are
homogeneous in quadratic order of the inverse lattice spacing, inhomogeneous in
first order, and satisfying a summability condition with respect to
higher-than-next neighbours.
| [
{
"version": "v1",
"created": "Wed, 18 Nov 1998 17:18:45 GMT"
},
{
"version": "v2",
"created": "Thu, 26 Nov 1998 15:24:57 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Polley",
"Lutz",
"",
"Oldenburg University, Germany"
]
] |
quant-ph/9811049 | Konstantin Krutitsky | K.V.Krutitsky, F.Burgbacher and J.Audretsch | Local-field approach to the interaction of an ultracold dense Bose gas
with a light field | 19 pages, RevTeX, to be published in the Physical Review A | Physical Review A 59(2), 1517-1527 (1999) | 10.1103/PhysRevA.59.1517 | null | quant-ph | null | The propagation of the electromagnetic field of a laser through a dense Bose
gas is examined and nonlinear operator equations for the motion of the center
of mass of the atoms are derived. The goal is to present a self-consistent set
of coupled Maxwell-Bloch equations for atomic and electromagnetic fields
generalized to include the atomic center-of-mass motion. Two effects are
considered: The ultracold gas forms a medium for the Maxwell field which
modifies its propagation properties. Combined herewith is the influence of the
dipole-dipole interaction between atoms which leads to a density dependent
shift of the atomic transition frequency. It is expressed in a position
dependent detuning and is the reason for the nonlinearity. This results in a
direct and physically transparent way from the quantum field theoretical
version of the local-field approach to electrodynamics in quantum media. The
equations for the matter fields are general. Previously published nonlinear
equations are obtained as limiting cases. As an atom optical application the
scattering of a dense beam of a Bose gas is studied in the Raman-Nath regime.
The main conclusion is that for increasing density of the gas the dipole-dipole
interaction suppresses or enhances the scattering depending on the sign of the
detuning.
| [
{
"version": "v1",
"created": "Thu, 19 Nov 1998 11:07:36 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Krutitsky",
"K. V.",
""
],
[
"Burgbacher",
"F.",
""
],
[
"Audretsch",
"J.",
""
]
] |
quant-ph/9811050 | Yu Shi | Yu Shi (Cavendish Laboratory) | Early Gedanken Experiments of Quantum Mechanics Revisited | 12 pages, published version | Annalen Phys.9:637-648,2000 | 10.1002/15= | null | quant-ph | null | The famous gedanken experiments of quantum mechanics have played crucial
roles in developing the Copenhagen interpretation. They are studied here from
the perspective of standard quantum mechanics, with no ontological
interpretation involved. Bohr's investigation of these gedanken experiments,
based on the uncertainty relation with his interpretation, was the origin of
the Copenhagen interpretation and is still widely adopted, but is shown to be
not consistent with the quantum mechanical view. We point out that in most of
these gedanken experiments, entanglement plays a crucial role, while its
buildup does not change the uncertainty of the concerned quantity in the way
thought by Bohr. Especially, in the gamma ray microscope and recoiling
double-slit gedanken experiments, we expose the entanglement based on momentum
exchange. It is shown that even in such cases, the loss of interference is only
due to the entanglement with other degrees of freedom, while the uncertainty
relation argument, which has not been questioned up to now, is not right.
| [
{
"version": "v1",
"created": "Thu, 19 Nov 1998 14:15:43 GMT"
},
{
"version": "v2",
"created": "Thu, 14 Jan 1999 18:22:15 GMT"
},
{
"version": "v3",
"created": "Mon, 9 Aug 1999 11:34:05 GMT"
},
{
"version": "v4",
"created": "Tue, 29 Aug 2000 21:29:09 GMT"
}
] | 2009-07-09T00:00:00 | [
[
"Shi",
"Yu",
"",
"Cavendish Laboratory"
]
] |
quant-ph/9811051 | John Klauder | John R. Klauder | Product Representations and the Quantization of Constrained Systems | latex, 15 pages, no figs, to appear in the Faddeev Festschrift | null | null | null | quant-ph hep-th math-ph math.MP | null | We study special systems with infinitely many degrees of freedom with regard
to dynamical evolution and fulfillment of constraint conditions. Attention is
focused on establishing a meaningful functional framework, and for that
purpose, coherent states and reproducing kernel techniques are heavily
exploited. Several examples are given.
| [
{
"version": "v1",
"created": "Thu, 19 Nov 1998 18:01:27 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Klauder",
"John R.",
""
]
] |
quant-ph/9811052 | Alexei Yu. Kitaev | S. B. Bravyi, A. Yu. Kitaev | Quantum codes on a lattice with boundary | LaTeX, 6 pages, 4 eps figures | null | null | null | quant-ph | null | A new type of local-check additive quantum code is presented. Qubits are
associated with edges of a 2-dimensional lattice whereas the stabilizer
operators correspond to the faces and the vertices. The boundary of the lattice
consists of alternating pieces with two different types of boundary conditions.
Logical operators are described in terms of relative homology groups.
| [
{
"version": "v1",
"created": "Fri, 20 Nov 1998 03:23:13 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Bravyi",
"S. B.",
""
],
[
"Kitaev",
"A. Yu.",
""
]
] |
quant-ph/9811053 | Michael Nielsen | M. A. Nielsen | Conditions for a class of entanglement transformations | 4 pages. Title and some nomenclature changed. Minor errors fixed | Physical Review Letters, Vol 83 (2), pp 436--439 (1999) | 10.1103/PhysRevLett.83.436 | null | quant-ph | null | Suppose Alice and Bob jointly possess a pure state, $|\psi\ra$. Using local
operations on their respective systems and classical communication it may be
possible for Alice and Bob to transform $|\psi\ra$ into another joint state
$|\phi\ra$. This Letter gives necessary and sufficient conditions for this
process of entanglement transformation to be possible. These conditions reveal
a partial ordering on the entangled states, and connect quantum entanglement to
the algebraic theory of majorization. As a consequence, we find that there
exist essentially different types of entanglement for bipartite quantum
systems.
| [
{
"version": "v1",
"created": "Fri, 20 Nov 1998 18:42:37 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Aug 1999 10:41:18 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Nielsen",
"M. A.",
""
]
] |
quant-ph/9811054 | Guido Bacciagaluppi | Harvey R. Brown (Oxford), Erik Sjoeqvist (Uppsala) and Guido
Bacciagaluppi (Oxford) | Remarks on identical particles in de Broglie-Bohm theory | RevTeX, 9 pp., to appear in Physics Letters A | Phys.Lett. A251 (1999) 229-235 | 10.1016/S0375-9601(98)00907-4 | null | quant-ph | null | It is argued that the topological approach to the (anti-)symmetrisation
condition for the quantum state of a collection of identical particles, defined
in the `reduced' configuration space, is particularly natural from the
perspective of de Broglie-Bohm pilot-wave theory.
| [
{
"version": "v1",
"created": "Fri, 20 Nov 1998 15:32:23 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Brown",
"Harvey R.",
"",
"Oxford"
],
[
"Sjoeqvist",
"Erik",
"",
"Uppsala"
],
[
"Bacciagaluppi",
"Guido",
"",
"Oxford"
]
] |
quant-ph/9811055 | Paul Benioff | Paul Benioff (Physics Division, Argonne National Laboratory) | A simple Example of Definitions of Truth, Validity, Consistency, and
Completeness in Quantum Mechanics | Revised description of quantum computer solution to existence
problem, other minor clarifications, typos, 30 pages Revtex, no Figures. To
Appear in Phys. Rev. A | Phys.Rev. A59 (1999) 4223 | 10.1103/PhysRevA.59.4223 | null | quant-ph | null | Besides their use for efficient computation, quantum computers are a base for
studying quantum systems that create valid physical theories using mathematics
and physics. An essential part of the validation process for quantum mechanics
is the development of a coherent theory of mathematics and quantum mechanics
together. Such a theory should combine mathematical logical concepts with
quantum mechanics. That this might be possible is shown here by defining truth,
validity, consistency, and completeness for a quantum mechanical version of a
simple classical expression enumeration machine described by Smullyan. It is
seen that for an interpretation based on a Feynman path sum over expression
path states, truth, consistency, and completeness have different properties
than for the classical system. For instance the truth of a sentence S is
defined only on the paths containing S. It is undefined elsewhere. Also S and
its negation can both be true provided they appear on separate paths. This
satisfies the definition of consistency. It is seen that validity and
completeness connect the system dynamics to the truth of the sentences. It is
proved that validity implies consistency. The requirements of validity and
maximal completeness strongly restrict the possible dynamics of the system.
Aspects of the existence of a valid, maximally complete dynamics are discussed.
An exponentially efficient quantum computer is described that is also valid and
complete.
| [
{
"version": "v1",
"created": "Fri, 20 Nov 1998 20:27:04 GMT"
},
{
"version": "v2",
"created": "Fri, 18 Dec 1998 22:21:44 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Benioff",
"Paul",
"",
"Physics Division, Argonne National Laboratory"
]
] |
quant-ph/9811056 | Samuel J. Lomonaco Jr. | Samuel J. Lomonaco | A Quick Glance at Quantum Cryptography | 54 pages, LaTeX with 6 figures as well as 3 graphics files embedded
as text on pages 40 and 41. To appear in Cryptologia. Document also found at
http://www.csee.umbc.edu/~lomonaco . In this version, problems with figures
have been corrected | null | null | null | quant-ph cs.CR | null | The recent application of the principles of quantum mechanics to cryptography
has led to a remarkable new dimension in secret communication. As a result of
these new developments, it is now possible to construct cryptographic
communication systems which detect unauthorized eavesdropping should it occur,
and which give a guarantee of no eavesdropping should it not occur.
CONTENTS P3. Cryptographic systems before quantum cryptography P7. Preamble
to quantum cryptography P10. The BB84 quantum cryptographic protocol without
noise P16. The BB84 quantum cryptographic protocol with noise P19..The B92
quantum cryptographic protocol P21. EPR quantum cryptographic protocols P25.
Other protocols P25. Eavesdropping stategies and counter measures P26.
Conclusion P29. Appendix A. The no cloning theorem P30. Appendix B. Proof that
an undetectable eavesdropper can obtain no information from the B92 protocol
P31. Appendix C. Part of a Rosetta stone for quantum mechanics P44. References
| [
{
"version": "v1",
"created": "Mon, 23 Nov 1998 04:57:47 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Lomonaco",
"Samuel J.",
""
]
] |
quant-ph/9811057 | Jerry Finkelstein | J. Finkelstein (LBNL and SJSU) | Space-time counterfactuals | LaTeX, 14 pages, includes two eps figures. Version 2: one example and
two references added; conclusions invariant | Synthese 119 (1999) 287-298 | null | SJSU/TP-98-19 | quant-ph | null | A definition is proposed to give precise meaning to the counterfactual
statements that often appear in discussions of the implications of quantum
mechanics. Of particular interest are counterfactual statements which involve
events occurring at space-like separated points, which do not have an absolute
time ordering. Some consequences of this definition are discussed.
| [
{
"version": "v1",
"created": "Sat, 21 Nov 1998 20:46:49 GMT"
},
{
"version": "v2",
"created": "Fri, 27 Nov 1998 20:29:52 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Finkelstein",
"J.",
"",
"LBNL and SJSU"
]
] |
quant-ph/9811058 | Luming Duan | Lu-Ming Duan and Guang-Can Guo (University of Science and Technology
of China) | Reducing spatially correlated noise and decoherence with quantum error
correcting codes | 8 pages, latex | null | null | null | quant-ph | null | It is shown that the noise process in quantum computation can be described by
spatially correlated decoherence and dissipation. We demonstrate that the
conventional quantum error correcting codes correcting for single-qubit errors
are applicable for reducing spatially correlated noise.
| [
{
"version": "v1",
"created": "Sun, 22 Nov 1998 08:57:13 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/9811059 | William Power | W. L. Power, I. C. Percival | Decoherence of quantum wavepackets due to interaction with conformal
spacetime fluctuations | REVTeX format | Proc.Roy.Soc.Lond.A456:955-968,2000 | 10.1098/rspa.2000.0544 | null | quant-ph gr-qc | null | One of the biggest problems faced by those attempting to combine quantum
theory and general relativity is the experimental inaccessibility of the
unification scale. In this paper we show how incoherent conformal waves in the
gravitational field, which may be produced by quantum mechanical zero-point
fluctuations, interact with the wavepackets of massive particles. The result of
this interaction is to produce decoherence within the wavepackets which could
be accessible in experiments at the atomic scale.
Using a simple model for the coherence properties of the gravitational field
we derive an equation for the evolution of the density matrix of such a
wavepacket. Following the primary state diffusion programme, the most promising
source of spacetime fluctuations for detection are the above zero-point energy
fluctuations. According to our model, the absence of intrinsic irremoveable
decoherence in matter interferometry experiments puts bounds on some of the
parameters of quantum gravity theories. Current experiments give \lambda > 18.
, where \lambda t_{Planck} is an effective cut-off for the validity of
low-energy quantum gravity theories.
| [
{
"version": "v1",
"created": "Mon, 23 Nov 1998 17:32:20 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Power",
"W. L.",
""
],
[
"Percival",
"I. C.",
""
]
] |
quant-ph/9811060 | Yoon-Ho Kim | Dmitry V. Strekalov, Yoon-Ho Kim, and Yanhua Shih | Experimental study of a photon as a subsystem of an entangled two-photon
state | 14 pages, 2 eps figures | Phys.Rev. A60 (1999) 2685 | 10.1103/PhysRevA.60.2685 | null | quant-ph | null | The state of the signal-idler photon pair of spontaneous parametric down
conversion(SPDC) is a typical nonlocal entangled pure state with zero entropy.
The precise correlation of the subsystems is completely described by the state.
However, it is an experimental choice to study only one subsystem and to ignore
the other. What can we learn about the measured subsystem and the remaining
parts? Results of this kind of measurements look peculiar. The experiment
confirms that the two subsystems are both in mixed states with entropy greater
than zero. One can only obtain statistical knowledge of the subsystems in this
kind of measurement.
| [
{
"version": "v1",
"created": "Mon, 23 Nov 1998 22:38:46 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Strekalov",
"Dmitry V.",
""
],
[
"Kim",
"Yoon-Ho",
""
],
[
"Shih",
"Yanhua",
""
]
] |
quant-ph/9811061 | A. B. Balantekin | A.B. Balantekin, M.A. Candido Ribeiro, and A.N.F. Aleixo | Algebraic Nature of Shape-Invariant and Self-Similar Potentials | 8 pages | J.Phys.A32:2785-2790,1999 | 10.1088/0305-4470/32/15/007 | MAD-NT-98-04 | quant-ph nucl-th | null | Self-similar potentials generalize the concept of shape-invariance which was
originally introduced to explore exactly-solvable potentials in quantum
mechanics. In this article it is shown that previously introduced algebraic
approach to the latter can be generalized to the former. The infinite Lie
algebras introduced in this context are shown to be closely related to the
q-algebras. The associated coherent states are investigated.
| [
{
"version": "v1",
"created": "Mon, 23 Nov 1998 23:39:40 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Balantekin",
"A. B.",
""
],
[
"Ribeiro",
"M. A. Candido",
""
],
[
"Aleixo",
"A. N. F.",
""
]
] |
quant-ph/9811062 | Jean-Michel Courty | Jean-Michel Courty, Francesca Grassia, Serge Reynaud (Laboratoire
Kastler Brossel) | Quantum noise in ideal operational amplifiers | 4 pages, 2 figures, RevTeX | Europhys.Lett. 46 (1999) 31-37 | 10.1209/epl/i1999-00558-3 | null | quant-ph | null | We consider a model of quantum measurement built on an ideal operational
amplifier operating in the limit of infinite gain, infinite input impedance and
null output impedance and with a feddback loop. We evaluate the intensity and
voltage noises which have to be added to the classical amplification equations
in order to fulfill the requirements of quantum mechanics. We give a
description of this measurement device as a quantum network scattering quantum
fluctuations from input to output ports.
| [
{
"version": "v1",
"created": "Tue, 24 Nov 1998 10:47:20 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Courty",
"Jean-Michel",
"",
"Laboratoire\n Kastler Brossel"
],
[
"Grassia",
"Francesca",
"",
"Laboratoire\n Kastler Brossel"
],
[
"Reynaud",
"Serge",
"",
"Laboratoire\n Kastler Brossel"
]
] |
quant-ph/9811063 | M. Dakna | J. Clausen, M. Dakna, L. Knoll and D.-G. Welsch | Conditional quantum-state transformation at a beam splitter | 7 Postscript figures, using Latex | null | 10.1088/1464-4266/1/3/306 | null | quant-ph | null | Using conditional measurement on a beam splitter, we study the transformation
of the quantum state of the signal mode within the concept of two-port
non-unitary transformation. Allowing for arbitrary quantum states of both the
input reference mode and the output reference mode on which the measurement is
performed, we show that the non-unitary transformation operator can be given as
an $s$-ordered operator product, where the value of $s$ is entirely determined
by the absolute value of the beam splitter reflectance (or transmittance). The
formalism generalizes previously obtained results that can be recovered by
simple specification of the non-unitary transformation operator. As an
application, we consider the generation of Schr\"odinger-cat-like states. An
extension to mixed states and imperfect detection is outlined.
| [
{
"version": "v1",
"created": "Tue, 24 Nov 1998 14:25:31 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Clausen",
"J.",
""
],
[
"Dakna",
"M.",
""
],
[
"Knoll",
"L.",
""
],
[
"Welsch",
"D. -G.",
""
]
] |
quant-ph/9811064 | Fabio Benatti | J. Andries, F. Benatti, M. De Cock, M. Fannes | Multi-time correlations in relaxing quantum dynamical systems | Plain Tex, 22 pages, no figures | Rev.Math.Phys. 12 (2000) 921-944 | null | KUL-TF-98/48 | quant-ph math-ph math.MP | null | In this paper, we consider the long time asymptotics of multi-time
correlation functions for quantum dynamical systems that are sufficiently
random to relax to a ``reference state''. In particular, the evolution of such
systems must have a continuous spectrum. Special attention is paid to general
dynamical clustering conditions and their consequences for the structure of
fluctuations of temporal averages.
| [
{
"version": "v1",
"created": "Tue, 24 Nov 1998 16:06:21 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Andries",
"J.",
""
],
[
"Benatti",
"F.",
""
],
[
"De Cock",
"M.",
""
],
[
"Fannes",
"M.",
""
]
] |
quant-ph/9811065 | Nikolay Vitanov | N. V. Vitanov and K.-A. Suominen | Nonlinear level crossing models | 9 pages final postscript file, two-column revtex style, 5 figures | null | 10.1103/PhysRevA.59.4580 | null | quant-ph | null | We examine the effect of nonlinearity at a level crossing on the probability
for nonadiabatic transitions $P$. By using the Dykhne-Davis-Pechukas formula,
we derive simple analytic estimates for $P$ for two types of nonlinear
crossings. In the first type, the nonlinearity in the detuning appears as a
{\it perturbative} correction to the dominant linear time dependence. Then
appreciable deviations from the Landau-Zener probability $P_{LZ}$ are found to
appear for large couplings only, when $P$ is very small; this explains why the
Landau-Zener model is often seen to provide more accurate results than
expected. In the second type of nonlinearity, called {\it essential}
nonlinearity, the detuning is proportional to an odd power of time. Then the
nonadiabatic probability $P$ is qualitatively and quantitatively different from
$P_{LZ}$ because on the one hand, it vanishes in an oscillatory manner as the
coupling increases, and on the other, it is much larger than $P_{LZ}$. We
suggest an experimental situation when this deviation can be observed.
| [
{
"version": "v1",
"created": "Tue, 24 Nov 1998 16:23:36 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Vitanov",
"N. V.",
""
],
[
"Suominen",
"K. -A.",
""
]
] |
quant-ph/9811066 | Nikolay Vitanov | N. V. Vitanov | Transition times in the Landau-Zener model | 7 pages, two-column revtex style, 5 figures, to appear in Phys. Rev.
A (Feb 1999) | null | 10.1103/PhysRevA.59.988 | null | quant-ph | null | This paper presents analytic formulas for various transition times in the
Landau-Zener model. Considerable differences are found between the transition
times in the diabatic and adiabatic bases, and between the jump time (the time
for which the transition probability rises to the region of its asymptotic
value) and the relaxation time (the characteristic damping time of the
oscillations which appear in the transition probability after the crossing).
These transition times have been calculated by using the exact values of the
transition probabilities and their derivatives at the crossing point and
approximations to the time evolutions of the transition probabilities in the
diabatic basis, derived earlier \protect{[}N. V. Vitanov and B. M. Garraway,
Phys. Rev. A {\bf 53}, 4288 (1996)\protect{]}, and similar results in the
adiabatic basis, derived in the present paper.
| [
{
"version": "v1",
"created": "Tue, 24 Nov 1998 17:30:30 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Vitanov",
"N. V.",
""
]
] |
quant-ph/9811067 | Stefan Scheel | S.Scheel, L.Knoll, D.-G.Welsch, and S.M.Barnett | Quantum local-field corrections and spontaneous decay | 7 pages, using RevTeX, 4 figures | null | 10.1103/PhysRevA.60.1590 | null | quant-ph | null | A recently developed scheme [S. Scheel, L. Knoll, and D.-G. Welsch, Phys.
Rev. A 58, 700 (1998)] for quantizing the macroscopic electromagnetic field in
linear dispersive and absorbing dielectrics satisfying the Kramers-Kronig
relations is used to derive the quantum local-field correction for the standard
virtual-sphere-cavity model. The electric and magnetic local-field operators
are shown to be consistent with QED only if the polarization noise is fully
taken into account. It is shown that the polarization fluctuations in the local
field can dramatically change the spontaneous decay rate, compared with the
familiar result obtained from the classical local-field correction. In
particular, the spontaneous emission rate strongly depends on the radius of the
local-field virtual cavity.
| [
{
"version": "v1",
"created": "Tue, 24 Nov 1998 19:02:02 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Scheel",
"S.",
""
],
[
"Knoll",
"L.",
""
],
[
"Welsch",
"D. -G.",
""
],
[
"Barnett",
"S. M.",
""
]
] |
quant-ph/9811068 | Lieven Vandersypen | Debbie Leung (1 and 2), Lieven Vandersypen (3 and 2), Xinlan Zhou (3
and 2), Mark Sherwood (2), Nino Yannoni (2), Mark Kubinec (4), Isaac Chuang
(2 and 3) ((1) Ginzton Laboratory, Stanford University, (2) IBM Almaden
Research Center, (3) Solid State and Photonics Laboratory, Stanford
University, (4) College of Chemistry, UC Berkeley) | Experimental Realization of A Two Bit Phase Damping Quantum Code | 21 pages, 17 figures, mypsfig2, revtex. Minor changes made to appear
in PRA | Phys.Rev. A60 (1999) 1924-1943 | 10.1103/PhysRevA.60.1924 | null | quant-ph | null | Using nuclear magnetic resonance techniques, we experimentally investigated
the effects of applying a two bit phase error detection code to preserve
quantum information in nuclear spin systems. Input states were stored with and
without coding, and the resulting output states were compared with the
originals and with each other. The theoretically expected result, net reduction
of distortion and conditional error probabilities to second order, was indeed
observed, despite imperfect coding operations which increased the error
probabilities by approximately 5%. Systematic study of the deviations from the
ideal behavior provided quantitative measures of different sources of error,
and good agreement was found with a numerical model. Theoretical questions in
quantum error correction in bulk nuclear spin systems including fidelity
measures, signal strength and syndrome measurements are discussed.
| [
{
"version": "v1",
"created": "Tue, 24 Nov 1998 23:52:17 GMT"
},
{
"version": "v2",
"created": "Tue, 25 May 1999 19:50:29 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Leung",
"Debbie",
"",
"1 and 2"
],
[
"Vandersypen",
"Lieven",
"",
"3 and 2"
],
[
"Zhou",
"Xinlan",
"",
"3\n and 2"
],
[
"Sherwood",
"Mark",
"",
"2 and 3"
],
[
"Yannoni",
"Nino",
"",
"2 and 3"
],
[
"Kubinec",
"Mark",
"",
"2 and 3"
],
[
"Chuang",
"Isaac",
"",
"2 and 3"
]
] |
quant-ph/9811069 | Masanao Ozawa | Masanao Ozawa and Harumichi Nishimura (Nagoya University) | Local Transition Functions of Quantum Turing Machines | 22 pages, LaTeX, revised and extended, to appear in RAIRO Theor.
Inform. Appl | Theoret. Informatics and Appl. 34 (2000) 379--402 | null | null | quant-ph | null | Foundations of the notion of quantum Turing machines are investigated.
According to Deutsch's formulation, the time evolution of a quantum Turing
machine is to be determined by the local transition function. In this paper,
the local transition functions are characterized for fully general quantum
Turing machines, including multi-tape quantum Turing machines, extending the
results due to Bernstein and Vazirani.
| [
{
"version": "v1",
"created": "Wed, 25 Nov 1998 04:09:31 GMT"
},
{
"version": "v2",
"created": "Tue, 26 Dec 2000 15:43:09 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ozawa",
"Masanao",
"",
"Nagoya University"
],
[
"Nishimura",
"Harumichi",
"",
"Nagoya University"
]
] |
quant-ph/9811070 | Stefan Weigert | Stefan Weigert | Gauge transformations for a driven quantum particle in an infinite
square well | 16 pages, no figures | Found. Phys. 29 (1999) 1785 | null | null | quant-ph math-ph math.MP | null | Quantum mechanics of a particle in an infinite square well under the
influence of a time-dependent electric field is reconsidered. In some gauge,
the Hamiltonian depends linearly on the momentum operator which is symmetric
but not self-adjoint when defined on a finite interval. In spite of this
symmetric part, the Hamiltonian operator is shown to be self-adjoint. This
follows from a theorem by Kato and Rellich which guarantees the stability of a
self-adjoint operator under certain symmetric perturbations. The result, which
has been assumed tacitly by other authors, is important in order to establish
the equivalence of different Hamiltonian operators related to each other by
quantum gauge transformations. Implications for the quantization procedure of a
particle in a box are pointed out.
| [
{
"version": "v1",
"created": "Wed, 25 Nov 1998 13:55:13 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Weigert",
"Stefan",
""
]
] |
quant-ph/9811071 | null | H.Razmi | An Alternative Commutation Relation Between Position and Momentum
Operators of Massless Particles | 6pages LaTeX | null | null | TMU-98-01 | quant-ph | null | It seems that the problem of finding a suitable position operator for photon
has been solved in a recently published work which is based on a new
commutation relation between position and momentum operators of massless
particles[1]. Although the authors of [1] have presented a classical reasoning
in favour of the new commutator,here we are going to find this new commutator
based on a quantum mechanical argument.
| [
{
"version": "v1",
"created": "Wed, 25 Nov 1998 15:16:44 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Razmi",
"H.",
""
]
] |
quant-ph/9811072 | Habibollah Razmi | H. Razmi | Mathematical and Physical Examination of the Locality Condition in
Bell's Theorem | 5 pages pdf; Physics Essays, Volume 19, No. 4 (2006) | null | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using the Clauser-Horne model of Bell's theorem, the locality condition is
examined and it is shown the corresponding formulation is equivalent to a
factorization process consisting of three stages. The first stage is introduced
based on the conditional probability definition in classical theory of
probability and the other two stages are based on previously-known relations
named as outcome and parameter independence conditions.
| [
{
"version": "v1",
"created": "Wed, 25 Nov 1998 15:35:28 GMT"
},
{
"version": "v2",
"created": "Mon, 10 Dec 2012 19:19:56 GMT"
}
] | 2012-12-11T00:00:00 | [
[
"Razmi",
"H.",
""
]
] |
quant-ph/9811073 | Eleanor G. Rieffel | Tad Hogg, Carlos Mochon, Wolfgang Polak, Eleanor Rieffel | Tools for Quantum Algorithms | LATEX, 15 pages, Minor changes: one author's e-mail and one reference
number | Int.J.Mod.Phys.C10:1347-1362,1999 | 10.1142/S0129183199001108 | FXPAL-TR-98-056 | quant-ph | null | We present efficient implementations of a number of operations for quantum
computers. These include controlled phase adjustments of the amplitudes in a
superposition, permutations, approximations of transformations and
generalizations of the phase adjustments to block matrix transformations. These
operations generalize those used in proposed quantum search algorithms.
| [
{
"version": "v1",
"created": "Wed, 25 Nov 1998 18:34:26 GMT"
},
{
"version": "v2",
"created": "Wed, 30 Dec 1998 19:29:31 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Hogg",
"Tad",
""
],
[
"Mochon",
"Carlos",
""
],
[
"Polak",
"Wolfgang",
""
],
[
"Rieffel",
"Eleanor",
""
]
] |
quant-ph/9811074 | Markus Simonius | Markus Simonius (ETH-Zuerich, Switzerland) | Measurement in Quantum Mechanics: From Probabilities to Objective Events | 16 pages A4, LaTeX, no figures | Helv.Phys.Acta 66 (1993) 721 | null | null | quant-ph | null | The problem of measurement in quantum mechanics is reanalyzed within a
general, strictly probabilistic framework (without reduction postulate). Based
on a novel comprehensive definition of measurement the natural emergence of
objective events is demonstrated and their formal representation within quantum
mechanics is obtained. In order to be objective an event is required to be
observable or readable in at least two independent, mutually non-interfering
ways with necessarily agreeing results. Consistency in spite of unrestricted
validity of reversibility of the evolution or the superposition principle is
demonstrated and the role played by state reduction, in a properly defined
restricted sense, is discussed. Some general consequences are pointed out.
| [
{
"version": "v1",
"created": "Thu, 26 Nov 1998 10:24:12 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Simonius",
"Markus",
"",
"ETH-Zuerich, Switzerland"
]
] |
quant-ph/9811075 | Michael Martin Nieto | Michael Martin Nieto and D. Rodney Truax | Time-dependent Schr\"odinger equations having isomorphic symmetry
algebras. I. Classes of interrelated equations | LaTeX, 18 pages, new format, edited | J.Math.Phys. 41 (2000) 2741-2752 | 10.1063/1.533268 | LA-UR-98-727 | quant-ph | null | In this paper, we focus on a general class of Schr\"odinger equations that
are time-dependent and quadratic in X and P. We transform Schr\"odinger
equations in this class, via a class of time-dependent mass equations, to a
class of solvable time-dependent oscillator equations. This transformation
consists of a unitary transformation and a change in the ``time'' variable. We
derive mathematical constraints forthe transformation and introduce two
examples.
| [
{
"version": "v1",
"created": "Thu, 26 Nov 1998 20:37:33 GMT"
},
{
"version": "v2",
"created": "Tue, 9 Nov 1999 13:59:03 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Nieto",
"Michael Martin",
""
],
[
"Truax",
"D. Rodney",
""
]
] |
quant-ph/9811076 | Michael Martin Nieto | Michael Martin Nieto and D. Rodney Truax | Time-dependent Schr\"odinger equations having isomorphic symmetry
algebras. II. Symmetry algebras, coherent and squeezed states | LaTeX, 22 pages, new format, edited, with added discussion of the
classical motion | J.Math.Phys. 41 (2000) 2753-2767 | 10.1063/1.533269 | LA-UR-98-726 | quant-ph | null | Using the transformations from paper I, we show that the Schr\"odinger
equations for: (1)systems described by quadratic Hamiltonians, (2) systems with
time-varying mass, and (3) time-dependent oscillators, all have isomorphic Lie
space-time symmetry algebras. The generators of the symmetry algebras are
obtained explicitly for each case and sets of number-operator states are
constructed. The algebras and the states are used to compute
displacement-operator coherent and squeezed states. Some properties of the
coherent and squeezed states are calculated. The classical motion of these
states is deomonstrated.
| [
{
"version": "v1",
"created": "Thu, 26 Nov 1998 20:42:25 GMT"
},
{
"version": "v2",
"created": "Tue, 9 Nov 1999 14:03:09 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Nieto",
"Michael Martin",
""
],
[
"Truax",
"D. Rodney",
""
]
] |
quant-ph/9811077 | Bg Sidharth | B.G. Sidharth | Quantized Space-Time and Time's Arrow | 3 pages, TeX | Chaos Solitons Fractals 11 (2000) 1045 | 10.1016/S0960-0779(98)00331-2 | null | quant-ph gr-qc | null | Motivated by the latest direct detection of time assymetry in Kaon decay at
CERN and Fermilab, we suggest a theoretical rationale for this puzzle, in terms
of quantized time.
| [
{
"version": "v1",
"created": "Fri, 27 Nov 1998 11:56:51 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Sidharth",
"B. G.",
""
]
] |
quant-ph/9811078 | Matteo G. A. Paris | Matteo G. A. Paris (Quantum Optics Group - University of Pavia ITALY) | Entanglement and visibility at the output of a Mach-Zehnder
interferometer | 6 figs, accepted for publication on PRA, see also
http://enterprise.pv.infn.it/~paris | Phys.Rev. A59 (1999) 1615 | 10.1103/PhysRevA.59.1615 | null | quant-ph | null | We study the entanglement between the two beams exiting a Mach-Zehnder
interferometer fed by a couple of squeezed-coherent states with arbitrary
squeezing parameter. The quantum correlations at the output are function of the
internal phase-shift of the interferometer, with the output state ranging from
a totally disentangled state to a state whose degree of entanglement is an
increasing function of the input squeezing parameter. A couple of squeezed
vacuum at the input leads to maximum entangled state at the output. The fringes
visibilities resulting from measuring the coincidence counting rate or the
squared difference photocurrent are evaluated and compared each other.
Homodyne-like detection turns out to be preferable in almost all situations,
with the exception of the very low signals regime.
| [
{
"version": "v1",
"created": "Fri, 27 Nov 1998 13:20:46 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Paris",
"Matteo G. A.",
"",
"Quantum Optics Group - University of Pavia ITALY"
]
] |
quant-ph/9811079 | Nikolay Vitanov | N. V. Vitanov, K.-A. Suominen, and B. W. Shore | Creation of coherent atomic superpositions by fractional STIRAP | 8 pages, two-column revtex style, 4 figures; paper copies with better
quality figures available upon request from the authors | null | null | null | quant-ph | null | We discuss a simple scheme for preparing atoms and molecules in an arbitrary
preselected coherent superposition of quantum states. The technique, which we
call fractional stimulated Raman adiabatic passage ({\it f-STIRAP}), is based
upon (incomplete) adiabatic population transfer between an initial state
$\psi_1$ and state $\psi_3$ through an intermediate state $\psi_2$. As in
STIRAP, the Stokes pulse arrives before the pump pulse, but unlike STIRAP, the
two pulses terminate simultaneously while maintaining a constant ratio of
amplitudes. The independence of f-STIRAP from details of pulse shape and pulse
area makes it the analog of conventional STIRAP in the creation of coherent
superpositions of states. We suggest a smooth realization of f-STIRAP which
requires only two laser pulses (which can be derived from a single laser) and
at the same time ensures the automatic fulfillment of the asymptotic conditions
at early and late times. Furthermore, we provide simple analytic estimates of
the robustness of f-STIRAP against variations in the pulse intensity, the pulse
delay, and the intermediate-state detuning, and discuss its possible extension
to multistate systems.
| [
{
"version": "v1",
"created": "Fri, 27 Nov 1998 14:31:28 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Vitanov",
"N. V.",
""
],
[
"Suominen",
"K. -A.",
""
],
[
"Shore",
"B. W.",
""
]
] |
quant-ph/9811080 | Andris Ambainis | Andris Ambainis | A note on quantum black-box complexity of almost all Boolean functions | 4 pages, LaTeX | Inform.Proc.Lett. 71 (1999) 5-7 | null | null | quant-ph cs.CC | null | We show that, for almost all N-variable Boolean functions f, at least
N/4-O(\sqrt{N} log N) queries are required to compute f in quantum black-box
model with bounded error.
| [
{
"version": "v1",
"created": "Sat, 28 Nov 1998 05:09:30 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ambainis",
"Andris",
""
]
] |
quant-ph/9811081 | D. Trifonov | D.A. Trifonov (Institute for nuclear research, Sofia) | Exact Solutions for the General Nonstationary Oscillator with a Singular
Perturbation | 17 pages, Latex, no figures; final form to appear in J. Phys. A | J.Phys.A32:3649-3661,1999 | 10.1088/0305-4470/32/19/314 | INRNE-TH-98/5 | quant-ph | null | Three linearly independent Hermitian invariants for the nonstationary
generalized singular oscillator (SO) are constructed and their complex linear
combination is diagonalized. The constructed family of eigenstates contains as
subsets all previously obtained solutions for the SO and includes all Robertson
and Schr\"odinger intelligent states for the three invariants. It is shown that
the constructed analogues of the SU(1,1) group-related coherent states for the
SO minimize the Robertson and Schr\"odinger relations for the three invariants
and for every pair of them simultaneously. The squeezing properties of the new
states are briefly discussed.
| [
{
"version": "v1",
"created": "Mon, 30 Nov 1998 09:45:30 GMT"
},
{
"version": "v2",
"created": "Sat, 5 Dec 1998 23:11:29 GMT"
},
{
"version": "v3",
"created": "Fri, 11 Dec 1998 17:36:21 GMT"
},
{
"version": "v4",
"created": "Fri, 18 Dec 1998 14:44:57 GMT"
},
{
"version": "v5",
"created": "Fri, 21 May 1999 06:53:35 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Trifonov",
"D. A.",
"",
"Institute for nuclear research, Sofia"
]
] |
quant-ph/9811082 | Carlton M. Caves | Carlton M. Caves | Quantum Error Correction and Reversible Operations | Paper based on a talk presented at the International Workshop on
Macroscopic Quantum Tunneling and Coherence, Naples, Italy, June 10-13, 1998;
to be published in Superconductivity; 17 pages, no figures, LaTeX | null | null | null | quant-ph | null | I give a pedagogical account of Shor's nine-bit code for correcting arbitrary
errors on single qubits, and I review work that determines when it is possible
to maintain quantum coherence by reversing the deleterious effects of
open-system quantum dynamics. The review provides an opportunity to introduce
an efficient formalism for handling superoperators. I present and prove some
bounds on entanglement fidelity, which might prove useful in analyses of
approximate error correction.
| [
{
"version": "v1",
"created": "Mon, 30 Nov 1998 00:13:22 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Caves",
"Carlton M.",
""
]
] |
quant-ph/9811083 | Taksu Cheon de Caracorum | Taksu Cheon (Kochi Tech), T. Shigehara (Saitama U) and K. Takayanagi
(Sophia U) | Equivalence of Local and Separable Realizations of the
Discontinuity-Inducing Contact Interaction and Its Perturbative
Renormalizability | ReVTeX 7pgs, doubl column, no figure, See also the website
http://www.mech.kochi-tech.ac.jp/cheon/ | J.Phys.Soc.Jap.69:345-350,2000 | 10.1143/JPSJ.69.345 | null | quant-ph cond-mat nlin.SI nucl-th solv-int | null | We prove that the separable and local approximations of the
discontinuity-inducing zero-range interaction in one-dimensional quantum
mechanics are equivalent. We further show that the interaction allows the
perturbative treatment through the coupling renormalization.
Keywords: one-dimensional system, generalized contact interaction,
renormalization, perturbative expansion. PACS Nos: 3.65.-w, 11.10.Gh, 31.15.Md
| [
{
"version": "v1",
"created": "Tue, 1 Dec 1998 00:20:21 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Cheon",
"Taksu",
"",
"Kochi Tech"
],
[
"Shigehara",
"T.",
"",
"Saitama U"
],
[
"Takayanagi",
"K.",
"",
"Sophia U"
]
] |
quant-ph/9811084 | Bg Sidharth | B.G. Sidharth | The Symmetry Underlying Spin and the Dirac Equation:FOOTPRINTS of
Quantized Space-Time | 8 pages, TeX, Full text of the paper at the Spin and Perturbation
Theory 98,symposium, Rome, 1998 | null | null | null | quant-ph gr-qc | null | It is shown, in the context of a recent formulation of elementary particles
in terms of, what may be called, a Quantum Mechanical Kerr-Newman metric, that
spin is a consequence of a space-time cut off at the Compton wavelength and
Compton time scale. On this basis, we deduce the Dirac equation from a simple
coordinate transformation. Time irreversibility is seen to follow providing a
rationale for the Kaon puzzle. So also, the handedness of the neutrino can be
explained.
| [
{
"version": "v1",
"created": "Mon, 30 Nov 1998 09:22:54 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sidharth",
"B. G.",
""
]
] |
quant-ph/9811085 | Kentaro Kato | Kentaro Kato, Masao Osaki, and Osamu Hirota | Derivation of classical capacity of quantum channel for discrete
information source | 9 pages, RevTeX, 3 figures(EPSF) | null | 10.1016/S0375-9601(98)00896-2 | null | quant-ph | null | In this letter, we prove that the classical capacity of quantum channel for
$M$ symmetric states is achieved by an uniform distribution on a priori
probabilities. We also investigate non-symmetric cases such as a ternary
amplitude shift keyed signal set and a 16-ary quadrature amplitude modulated
signal set in coherent states.
| [
{
"version": "v1",
"created": "Mon, 30 Nov 1998 09:30:19 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Kato",
"Kentaro",
""
],
[
"Osaki",
"Masao",
""
],
[
"Hirota",
"Osamu",
""
]
] |
quant-ph/9811086 | Dr N. Nayak | N. Nayak | Effect of dissipative forces on the theory of a single-atom microlaser | 9 pages in LaTex; 3 PS figures | Optics Letters, january 1999 | 10.1364/OL.24.000013 | null | quant-ph | null | We describe a one-atom microlaser involving Poissonian input of atoms with a
fixed flight time through an optical resonator. The influence of the cavity
reservoir during the interactions of successive individual atoms with the
cavity field is included in the analysis. The atomic decay is also considered
as it is nonnegligible in the optical regime. During the random intervals of
absence of any atom in the cavity, the field evolves under its own dynamics. We
discuss the steady-state characteristics of the cavity field. Away from laser
threshold, the field can be nonclassical in nature.
| [
{
"version": "v1",
"created": "Mon, 30 Nov 1998 09:32:53 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Nayak",
"N.",
""
]
] |
quant-ph/9811087 | Alex Moroz | Alexander Moroz (FOM AMOLF, Amsterdam) | Comments on ``Differential cross section for Aharonov-Bohm effect with
nonstandard boundary conditions'' | 4 pages, plain latex, Author URL
http://www.amolf.nl/external/wwwlab/atoms/theory/, replaced with final
version | Europhys.Lett.46:273-274,1999 | 10.1209/epl/i1999-00383-8 | null | quant-ph | null | We show that the violation of rotational symmetry for differential cross
section for Aharonov-Bohm effect with nonstandard boundary conditions has been
known for some time. Moreover, the results were applied to discuss the Hall
effect and persistent currents of fermions in a plane pierced by a flux tube.
| [
{
"version": "v1",
"created": "Mon, 30 Nov 1998 10:50:21 GMT"
},
{
"version": "v2",
"created": "Wed, 14 Jul 1999 07:04:11 GMT"
}
] | 2010-12-17T00:00:00 | [
[
"Moroz",
"Alexander",
"",
"FOM AMOLF, Amsterdam"
]
] |
quant-ph/9811088 | Miloslav Znojil | Miloslav Znojil (Institute of Nuclear Physics, Rez, Czech Republic) | The conditionally exactly solvable potentials: A misunderstanding
(comment on "Conditionally exactly soluble class of quantum potentials") | extended and published version | Phys.Rev. A61 (2000) 066101 | 10.1103/PhysRevA.61.066101 | null | quant-ph | null | In the paper "Conditionally exactly soluble class of quantum potentials" by
A. de Souza Dutra [Phys. Rev. A 47 (1993) R2435] the whole $s-$wave spectrum of
bound states in potentials $V_1(r)=A/r+B/r^{1/2}+G_0/r^2$ with
$G_0=-3\hbar/32\mu$ and $V_2(r)=A r^{2/3}+B/r^{2/3}+g_0/r^2$ with
$g_0=-5\hbar^2/72\mu$ has been constructed in closed form. We show that both
the result and the method of its derivation are not correct.
| [
{
"version": "v1",
"created": "Mon, 30 Nov 1998 12:53:20 GMT"
},
{
"version": "v2",
"created": "Mon, 10 Feb 2003 09:24:34 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Znojil",
"Miloslav",
"",
"Institute of Nuclear Physics, Rez, Czech Republic"
]
] |
quant-ph/9811089 | Ian C. Percival | i.c.percival | Cosmic quantum measurement | 18 pages, 3 figures, t.bbl file. Latex inserts the figures | Proc.Roy.Soc.Lond. A456 (2000) 25-37 | 10.1098/rspa.2000.0507 | null | quant-ph gr-qc | null | Hardy's theorem states that the hidden variables of any realistic theory of
quantum measurement, whose predictions agree with ordinary quantum theory, must
have a preferred Lorentz frame. This presents the conflict between special
relativity and any realistic dynamics of quantum measurement in a severe form.
The conflict is resolved using a `measurement field', which provides a timelike
function of spacetime points and a definition of simultaneity in the context of
a curved spacetime. Locally this theory is consistent with special relativity,
but globally, special relativity is not enough; the time dilation of general
relativity and the standard cosmic time of the Robertson-Walker cosmologies are
both essential. A simple but crude example is a relativistic quantum
measurement dynamics based on the nonrelativistic measurement dynamics of
L\"uders.
| [
{
"version": "v1",
"created": "Mon, 30 Nov 1998 16:05:33 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"percival",
"i. c.",
""
]
] |
quant-ph/9811090 | Tomas Opatrny | T. Opatrny and G. Kurizki | Optimization approach to entanglement distillation | 6 pages, 5 figures, REVTEX. New examples, figures and references,
more detailed explanations. To appear in Phys. Rev. A | Phys.Rev. A60 (1999) 167-172 | 10.1103/PhysRevA.60.167 | null | quant-ph | null | We put forward a method for optimized distillation of partly entangled pairs
of qubits into a smaller number of more entangled pairs by recurrent local
unitary operations and projections. Optimized distillation is achieved by
minimization of a cost function with up to 30 real parameters, which is chosen
to be sensitive to the fidelity and the projection probability at each step. We
show that in many cases this approach can significantly improve the
distillation efficiency in comparison to the present methods.
| [
{
"version": "v1",
"created": "Mon, 30 Nov 1998 17:38:49 GMT"
},
{
"version": "v2",
"created": "Fri, 9 Apr 1999 08:02:15 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Opatrny",
"T.",
""
],
[
"Kurizki",
"G.",
""
]
] |
quant-ph/9811091 | Ashish Thapliyal | Ashish V. Thapliyal | On Multipartite Pure-State Entanglement | 8 Pages ReVTeX, 4 figures (eps); v2: Revised terminology, added two
references and other minor changes; v3: Minor changes, added two references,
added author's middle initial; v4: One footnote removed | Phys.Rev. A59 (1999) 3336 | 10.1103/PhysRevA.59.3336 | null | quant-ph | null | We show that pure states of multipartite quantum systems are multiseparable
(i.e. give separable density matrices on tracing any party) if and only if they
have a generalized Schmidt decomposition. Implications of this result for the
quantification of multipartite pure-state entanglement are discussed. Further,
as an application of the techniques used here, we show that any purification of
a bipartite PPT bound entangled state is tri-inseparable, i.e. has none of its
three bipartite partial traces separable.
| [
{
"version": "v1",
"created": "Mon, 30 Nov 1998 18:52:10 GMT"
},
{
"version": "v2",
"created": "Wed, 23 Dec 1998 21:58:43 GMT"
},
{
"version": "v3",
"created": "Tue, 9 Feb 1999 17:49:14 GMT"
},
{
"version": "v4",
"created": "Thu, 18 Feb 1999 17:34:51 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Thapliyal",
"Ashish V.",
""
]
] |
quant-ph/9811092 | Lev Vaidman | L. Vaidman | Defending Time-Symmetrized Quantum Counterfactuals | 22 pages | null | null | null | 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, (Vaidman, 1996a, 1997) have argued that the
apparent contradiction is due to a logical error and introduced consistent
time-symmetrized quantum counterfactuals. Here I repeat my arguments defending
the time-symmetrized quantum theory and reply to the criticism of these
arguments by Kastner (1999).
| [
{
"version": "v1",
"created": "Mon, 30 Nov 1998 22:34:20 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Vaidman",
"L.",
""
]
] |
quant-ph/9812001 | Vladimir Buzek | V.Buzek, G. Drobny, Min Gyu Kim, M. Havukainen, and P.L. Knight | Numerical simulations of fundamental processes in cavity QED: Atomic
decay | 13 pages, revtex, 10 figures | null | null | null | quant-ph | null | We present results of numerical investigation of a microscopic dynamics of a
two-level atom embedded into a ``linear crystal'' of other two-level atoms.
These additional atoms play a role of a material media. All atoms interact with
a multimode cavity field. We study how the decay of the initially excited atom
is affected by the presence of material media and spectral properties of the
cavity field.
| [
{
"version": "v1",
"created": "Tue, 1 Dec 1998 13:39:47 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Buzek",
"V.",
""
],
[
"Drobny",
"G.",
""
],
[
"Kim",
"Min Gyu",
""
],
[
"Havukainen",
"M.",
""
],
[
"Knight",
"P. L.",
""
]
] |
quant-ph/9812002 | Victor Red'kov | V. M. Red'kov | Generally relativistical Tetrode-Weyl-Fock-Ivanenko formalism and
behaviour of quantum-mechanical particles of spin 1/2 in the Abelian monopole
field | 27 pages, Latex209 | null | null | null | quant-ph | null | Some attention in the literature has been given to the case of a particle of
spin 1/2 on the background of the external monopole potential. Some aspects of
this problem are reexamined here. The primary technical novelty is that the
tetrad generally relativistic method of Tetrode-Weyl-Fock-Ivanenko for
describing a spinor particle is exploited. The choice of the formalism has
turned out to be of great fruitfulness for examining the system. It is matter
that, as known, the use of a special spherical tetrad in the theory of a spin
1/2 particle had led Schrodinger to a basis of remarkable features. The basis
has been used with great efficiency by Pauli in his investigation on the pro-
blem of allowed spherically symmetric wave functions in quantum mechanics. For
our purposes, just several simple rules extracted from the much more com-
prehensive Pauli's analysis will be quite sufficient; those are almost mnemo-
nic working regulations. So, one may remember some very primary facts of D-
functions theory and then produce automatically proper wave functions. It seems
rather likely, that there may exist a generalized analog of such a re-
presentation for J(i)-operators, that might be successfully used whenever in a
linear problem there exists a spherical symmetry, irrespective of the con-
crete embodiment of such a symmetry. In particular, the case of electron in the
external Abelian monopole field completely come under the Sch-Pau method.
| [
{
"version": "v1",
"created": "Tue, 1 Dec 1998 16:26:00 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Red'kov",
"V. M.",
""
]
] |
quant-ph/9812003 | Oscar Rosas-Ortiz | J. Oscar Rosas-Ortiz | On the factorization method in quantum mechanics | 15 pages, LaTex file, minor changes | Proceedings of the First International Workshop on ``Symmetries in
Quantum Mechanics and Quantum Optics''. A. Ballesteros et al (Eds.) Servicio
de Publicaciones de la Universidad de Burgos (Spain), p. 285-299. Burgos,
Spain (1999) | null | null | quant-ph | null | New exactly solvable problems have already been studied by using a
modification of the factorization method introduced by Mielnik. We review this
method and its connection with the traditional factorization method. The survey
includes the discussion on a generalization of the factorization energies used
in the traditional Infeld and Hull method.
| [
{
"version": "v1",
"created": "Tue, 1 Dec 1998 17:13:02 GMT"
},
{
"version": "v2",
"created": "Thu, 14 Oct 1999 20:26:23 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rosas-Ortiz",
"J. Oscar",
""
]
] |
quant-ph/9812004 | Kurt Jacobs | A. C. Doherty and K. Jacobs(Department of Physics, University of
Auckland, NZ) | Feedback-control of quantum systems using continuous state-estimation | 12 pages, multicol revtex, revised and extended | Phys.Rev. A60 (1999) 2700 | 10.1103/PhysRevA.60.2700 | null | quant-ph | null | We present a formulation of feedback in quantum systems in which the best
estimates of the dynamical variables are obtained continuously from the
measurement record, and fed back to control the system. We apply this method to
the problem of cooling and confining a single quantum degree of freedom, and
compare it to current schemes in which the measurement signal is fed back
directly in the manner usually considered in existing treatments of quantum
feedback. Direct feedback may be combined with feedback by estimation, and the
resulting combination, performed on a linear system, is closely analogous to
classical LQG control theory with residual feedback.
| [
{
"version": "v1",
"created": "Tue, 1 Dec 1998 21:57:06 GMT"
},
{
"version": "v2",
"created": "Tue, 22 Jun 1999 22:49:01 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Doherty",
"A. C.",
"",
"Department of Physics, University of\n Auckland, NZ"
],
[
"Jacobs",
"K.",
"",
"Department of Physics, University of\n Auckland, NZ"
]
] |
quant-ph/9812005 | Hitoshi Miyazaki | K.Horie, H.Miyazaki, I.Tsutsui and S.Tanimura | Quantum caustics in the Gaussian slit experiment | TeX, 11 pages, No figures | Phys.Lett. A253 (1999) 259-265 | 10.1016/S0375-9601(99)00079-1 | null | quant-ph hep-th | null | We study classical and quantum caustics for system with quadratic Lagrangian.
Gaussian slit experiment is examined and it is pointed out that the focusing
around caustics is stabilized against initial momentum fluctuations by quantum
effect.
| [
{
"version": "v1",
"created": "Wed, 2 Dec 1998 05:39:34 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Horie",
"K.",
""
],
[
"Miyazaki",
"H.",
""
],
[
"Tsutsui",
"I.",
""
],
[
"Tanimura",
"S.",
""
]
] |
quant-ph/9812006 | Taksu Cheon de Caracorum | T. Shigehara, H. Mizoguchi, T. Mishima (Saitama U) and Taksu Cheon
(Kochi Tech) | Realization of a Four Parameter Family of Generalized One-Dimensional
Contact Interactions by Three Nearby Delta Potentials with Renormalized
Strengths | LaTeX 6pgs, IEICE doubl column, three figures (incl.), See also the
website http://www.mech.kochi-tech.ac.jp/cheon/ | IEICE Trans.Fund.Elec.Comm.Comp.Sci. E82-A (1999) 1708-1713 | null | null | quant-ph cond-mat nucl-th | null | We propose a new method to construct a four parameter family of
quantum-mechanical point interactions in one dimension, which is known as all
possible self-adjoint extensions of the symmetric operator $T=-\Delta \lceil
C^{\infty}_{0}({\bf R} \backslash\{0\})$. It is achieved in the small distance
limit of equally spaced three neighboring Dirac's $\delta$ potentials. The
strength for each $\delta$ is appropriately renormalized according to the
distance and it diverges, in general, in the small distance limit. The validity
of our method is ensured by numerical calculations. In general cases except for
usual $\delta$, the wave function discontinuity appears around the interaction
and one can observe such a tendency even at a finite distance level.
| [
{
"version": "v1",
"created": "Wed, 2 Dec 1998 08:30:16 GMT"
},
{
"version": "v2",
"created": "Wed, 24 Feb 1999 07:04:28 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Shigehara",
"T.",
"",
"Saitama U"
],
[
"Mizoguchi",
"H.",
"",
"Saitama U"
],
[
"Mishima",
"T.",
"",
"Saitama U"
],
[
"Cheon",
"Taksu",
"",
"Kochi Tech"
]
] |
quant-ph/9812007 | Victor Red'kov | V M Red'kov | Generally relativistical Daffin-Kemmer formalis and behaviour of
quantm-mechanical particle of spin 1 in the Abelian monopole field | 17 pages, Latex209 | null | null | null | quant-ph | null | It is shown that the manner of introducing theinteraction between a spin 1
particle and external classical gravitational field can be successfully uni-
fied with the approach that occurred with regard to a spin 1/2 particle and was
first developed by Tetrode, Weyl, Fock, Ivanenko. On that way a general- ly
relativistical Duffin-Kemmer equation is costructed. So, the manner of
extending the flat space Dirac equation to general relativity case indicates
clearly that the Lorentz group underlies equally both these theories. In other
words, the Lorentz group retains its importance and significance at changing
the Minkowski space model to an arbitrary curved space-time. In contrast to
this, at generalizing the Proca formulation, we automatically destroy any
relations to the Lorentz group, although the definition itself for a spin 1
particle as an elementary object was based on just this group. Such a gravity's
sensitiveness to the fermion-boson division might appear rather strange and
unattractive asymmetry, being subjected to the criticism. Moreover, just this
feature has brought about a plenty of speculation on this matter. In any case,
this peculiarity of particle-gravity field inter- action is recorded almost in
every handbook. In the paper, on the base of the Duffin-Kemmer formalism
developed, the problem of a vector particle in the Abelian monopole potential
is considered.
| [
{
"version": "v1",
"created": "Wed, 2 Dec 1998 11:47:34 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Red'kov",
"V M",
""
]
] |
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