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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/9804006 | Matteo Buzzacchi | M. Buzzacchi, E. Del Giudice, G. Preparata | Sonoluminescence Unveiled ? | LaTeX, 3 postscript figures | null | null | null | quant-ph | null | The widening phenomenology of Single Bubble Sonoluminescence (SBSL) is shown
to be in good agreement with a new approach to condensed matter, based on the
QED coherent interactions. Some remarkable properties of SBSL are shown to
emerge from the electromagnetic release of part of the latent heat of the
water's vapour-liquid phase transition occurring at the bubble surface after it
becomes supersonic.
| [
{
"version": "v1",
"created": "Thu, 2 Apr 1998 08:16:27 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Buzzacchi",
"M.",
""
],
[
"Del Giudice",
"E.",
""
],
[
"Preparata",
"G.",
""
]
] |
quant-ph/9804007 | Carlos Cabrillo | C. Cabrillo, J. L. Roldan, P. Garcia-Fernandez | Quantum noise reduction in singly resonant sub/second harmonic
generation | 3 two column pages, two figures | null | null | null | quant-ph physics.optics | null | We study the quantum noise in the harmonic mode of a singly resonant
frequency doubler simultaneously driven in both modes. This simple extension of
the frequency doubler greatly improves its performance as a bright squeezed
light source. Specifically, for parameters corresponding to reported
experiments, 80 % of noise suppression is easily achieved, the phase of the
corresponding squeezed quadrature can be freely and easily chosen, and the
output power is nearly doubled.
| [
{
"version": "v1",
"created": "Thu, 2 Apr 1998 09:50:49 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Cabrillo",
"C.",
""
],
[
"Roldan",
"J. L.",
""
],
[
"Garcia-Fernandez",
"P.",
""
]
] |
quant-ph/9804008 | Andrew Gray | Andrew Gray | A Design for a Quantum Time Machine | This paper has been withdrawn | null | null | null | quant-ph | null | This paper has been retracted, for obvious reasons.
| [
{
"version": "v1",
"created": "Thu, 2 Apr 1998 18:51:30 GMT"
},
{
"version": "v2",
"created": "Sun, 8 Aug 2004 18:25:20 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gray",
"Andrew",
""
]
] |
quant-ph/9804009 | John Klauder | John R. Klauder (University of Florida) | Metrical Quantization | 13 pages, LaTeX, no figures, to appear in Born X Proceedings | null | 10.1007/BFb0105343 | null | quant-ph hep-th math-ph math.MP | null | Canonical quantization may be approached from several different starting
points. The usual approaches involve promotion of c-numbers to q-numbers, or
path integral constructs, each of which generally succeeds only in Cartesian
coordinates. All quantization schemes that lead to Hilbert space vectors and
Weyl operators---even those that eschew Cartesian coordinates---implicitly
contain a metric on a flat phase space. This feature is demonstrated by
studying the classical and quantum ``aggregations'', namely, the set of all
facts and properties resident in all classical and quantum theories,
respectively. Metrical quantization is an approach that elevates the flat phase
space metric inherent in any canonical quantization to the level of a
postulate. Far from being an unwanted structure, the flat phase space metric
carries essential physical information. It is shown how the metric, when
employed within a continuous-time regularization scheme, gives rise to an
unambiguous quantization procedure that automatically leads to a canonical
coherent state representation. Although attention in this paper is confined to
canonical quantization we note that alternative, nonflat metrics may also be
used, and they generally give rise to qualitatively different, noncanonical
quantization schemes.
| [
{
"version": "v1",
"created": "Thu, 2 Apr 1998 22:10:42 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Klauder",
"John R.",
"",
"University of Florida"
]
] |
quant-ph/9804010 | David Meyer | David A. Meyer (University of California/San Diego) | Quantum strategies | 8 pages, plain TeX, 1 figure | Phys.Rev.Lett. 82 (1999) 1052-1055 | 10.1103/PhysRevLett.82.1052 | null | quant-ph | null | We consider game theory from the perspective of quantum algorithms.
Strategies in classical game theory are either pure (deterministic) or mixed
(probabilistic). We introduce these basic ideas in the context of a simple
example, closely related to the traditional Matching Pennies game. While not
every two-person zero-sum finite game has an equilibrium in the set of pure
strategies, von Neumann showed that there is always an equilibrium at which
each player follows a mixed strategy. A mixed strategy deviating from the
equilibrium strategy cannot increase a player's expected payoff. We show,
however, that in our example a player who implements a quantum strategy can
increase his expected payoff, and explain the relation to efficient quantum
algorithms. We prove that in general a quantum strategy is always at least as
good as a classical one, and furthermore that when both players use quantum
strategies there need not be any equilibrium, but if both are allowed mixed
quantum strategies there must be.
| [
{
"version": "v1",
"created": "Fri, 3 Apr 1998 00:22:38 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Meyer",
"David A.",
"",
"University of California/San Diego"
]
] |
quant-ph/9804011 | Paolo-Zanardi | Paolo Zanardi (1) ((1) Institute for Scientific Interchange
Foundation, Villa Gualino, and Unit\`a INFM, Politecnico di Torino) | Quantum Cloning in $d$ dimensions | 8 pages LaTeX, no figures | Phys.Rev. A58 (1998) 3484 | 10.1103/PhysRevA.58.3484 | null | quant-ph | null | The quantum state space $\cal S$ over a $d$-dimensional Hilbert space is
represented as a convex subset of a $D-1$-dimensional sphere $S_{D-1}\subset
{\bf{R}}^D$, where $D=d^2-1.$ Quantum tranformations (CP-maps) are then
associated with the affine transformations of ${\bf{R}}^D,$ and $N\mapsto M$
{\it cloners} induce polynomial mappings. In this geometrical setting it is
shown that an optimal cloner can be chosen covariant and induces a map between
reduced density matrices given by a simple contraction of the associated
$D$-dimensional Bloch vectors.
| [
{
"version": "v1",
"created": "Fri, 3 Apr 1998 07:04:39 GMT"
},
{
"version": "v2",
"created": "Thu, 19 Nov 1998 17:34:32 GMT"
},
{
"version": "v3",
"created": "Fri, 20 Nov 1998 09:13:28 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Zanardi",
"Paolo",
""
]
] |
quant-ph/9804012 | Ariel Caticha | Ariel Caticha | Consistency, Amplitudes and Probabilities in Quantum Theory | 23 pages, 3 figures (old version did not include the figures) | Phys.Rev. A57 (1998) 1572 | 10.1103/PhysRevA.57.1572 | null | quant-ph cond-mat.stat-mech gr-qc | null | Quantum theory is formulated as the only consistent way to manipulate
probability amplitudes. The crucial ingredient is a consistency constraint: if
there are two different ways to compute an amplitude the two answers must
agree. This constraint is expressed in the form of functional equations the
solution of which leads to the usual sum and product rules for amplitudes. A
consequence is that the Schrodinger equation must be linear: non-linear
variants of quantum mechanics are inconsistent. The physical interpretation of
the theory is given in terms of a single natural rule. This rule, which does
not itself involve probabilities, is used to obtain a proof of Born's
statistical postulate. Thus, consistency leads to indeterminism.
PACS: 03.65.Bz, 03.65.Ca.
| [
{
"version": "v1",
"created": "Fri, 3 Apr 1998 21:35:45 GMT"
},
{
"version": "v2",
"created": "Sat, 4 Apr 1998 17:23:28 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Caticha",
"Ariel",
""
]
] |
quant-ph/9804013 | null | Guang-jiong Ni (Department of Physics, Fudan University and Shanghai,
P. R. China) | To Enjoy the Morning Flower in the Evening -- Where is the Subtlety of
Quantum Mechanics? | 14 pages, LaTex, no figure | null | null | null | quant-ph | null | Why does the $i=\sqrt{-1}$ appear essentially in the quantum mechanics? Why
are there operators and noncommutativity (the uncertainty relation) in the
quantum mechanics? Why are these two aspects closely related and indivisible?
In probing these problems, a new point of view is proposed tentatively.
| [
{
"version": "v1",
"created": "Sun, 5 Apr 1998 09:08:25 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ni",
"Guang-jiong",
"",
"Department of Physics, Fudan University and Shanghai,\n P. R. China"
]
] |
quant-ph/9804014 | Hao | Lu-Ming Duan and Guang-Can Guo (University of Science and Technology
of China) | Optimal quantum codes for preventing collective amplitude damping | 14 pages, Latex | null | 10.1103/PhysRevA.58.3491 | null | quant-ph | null | Collective decoherence is possible if the departure between quantum bits is
smaller than the effective wave length of the noise field. Collectivity in the
decoherence helps us to devise more efficient quantum codes. We present a class
of optimal quantum codes for preventing collective amplitude damping to a
reservoir at zero temperature. It is shown that two qubits are enough to
protect one bit quantum information, and approximately $L+ 1/2 \log_2((\pi
L)/2)$ qubits are enough to protect $L$ qubit information when $L$ is large.
For preventing collective amplitude damping, these codes are much more
efficient than the previously-discovered quantum error correcting or avoiding
codes.
| [
{
"version": "v1",
"created": "Mon, 6 Apr 1998 09:59:46 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Duan",
"Lu-Ming",
"",
"University of Science and Technology\n of China"
],
[
"Guo",
"Guang-Can",
"",
"University of Science and Technology\n of China"
]
] |
quant-ph/9804015 | Irene Marzoli | I. Marzoli (1), I. Bialynicki-Birula (2), O. M. Friesch (1), A. E.
Kaplan (3)and W. P. Schleich (1) ((1) Universitaet Ulm, Ulm, Germany, (2)
Center for Theoretical Physics, Warsaw, Poland, (3) The Johns Hopkins
University, Baltimore, USA) | The Particle in the box: Intermode traces in the propagator | 10 pages, 2 figures. It will appear in the Proc. of the PRL Golden
Jubilee Conference on Nonlinear Dynamics and Computational Physics (Narosa
Publishing House, New Delhi) | null | null | null | quant-ph | null | Characteristic structures such as canals and ridges --intermode traces--
emerge in the spacetime representation of the probability distribution of a
particle in a one-dimensional box. We show that the corresponding propagator
already contains these structures. We relate their visibility to the
factorization property of the initial wave packet.
| [
{
"version": "v1",
"created": "Mon, 6 Apr 1998 15:20:22 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Marzoli",
"I.",
""
],
[
"Bialynicki-Birula",
"I.",
""
],
[
"Friesch",
"O. M.",
""
],
[
"Kaplan",
"A. E.",
""
],
[
"Schleich",
"and W. P.",
""
]
] |
quant-ph/9804016 | Paolo-Zanardi | Paolo Zanardi (1 and 2) and Fausto Rossi (1 and 3) ((1) Istituto
Nazionale per la Fisica della Materia (INFM) (2) Institute for Scientific
Interchange Foundation (ISI), and Unit\`a INFM, Politecnico di Torino (3)
Dipartimento di Fisica, Universit\`a di Modena) | Quantum Information in Semiconductors: Noiseless Encoding in a
Quantum-Dot Array | 5 pages LaTeX, 3 encapsulated postscript figures. Final version
accepted by PRL | Phys.Rev.Lett. 81 (1998) 4572-4575 | 10.1103/PhysRevLett.81.4752 | null | quant-ph cond-mat | null | A potential implementation of quantum-computation schemes in
semiconductor-based structures is proposed. In particular, an array of quantum
dots is shown to be an ideal quantum register for a noiseless information
encoding. In addition to the suppression of phase-breaking processes in quantum
dots due to the well-known phonon bottleneck, we show that a proper quantum
encoding allows to realise a decoherence-free evolution on a time-scale long
compared to the femtosecond scale of modern ultrafast laser technology. This
result might open the way to the realization of semiconductor-based quantum
processors.
| [
{
"version": "v1",
"created": "Mon, 6 Apr 1998 17:15:22 GMT"
},
{
"version": "v2",
"created": "Fri, 20 Nov 1998 08:49:09 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Zanardi",
"Paolo",
"",
"1 and 2"
],
[
"Rossi",
"Fausto",
"",
"1 and 3"
]
] |
quant-ph/9804017 | Jozef Skvarcek | Mark Hillery and Jozef Skvarcek | Field Oscillations in a Micromaser with Injected Atomic Coherence | 8 pages, 4 PostScript figures, LaTex2e document | null | 10.1080/09500349808230664 | Physics-HC-CUNY-98-04 | quant-ph | null | The electric field in a lossless, regularly-pumped micromaser with injected
atomic coherence can undergo a period 2 oscillations in the steady state. The
field changes its value after a single atom passes through the micromaser
cavity, but returns to its original value after a second atom travels through.
We give a simple explanation for this phenomenon in terms of tangent and
cotangent states. We also examine the effect of cavity damping on this steady
state.
| [
{
"version": "v1",
"created": "Mon, 6 Apr 1998 17:38:16 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Hillery",
"Mark",
""
],
[
"Skvarcek",
"Jozef",
""
]
] |
quant-ph/9804018 | Ady Stern | Yakir Aharonov (Tel-Aviv and South Carolina) Benni Reznik (Los Alamos)
and Ady Stern (Weizmann) | Quantum limitations on superluminal propagation | RevTeX 4 pages | Phys.Rev.Lett. 81 (1998) 2190-2193 | 10.1103/PhysRevLett.81.2190 | null | quant-ph cond-mat gr-qc hep-th | null | Unstable systems such as media with inverted atomic population have been
shown to allow the propagation of analytic wavepackets with group velocity
faster than that of light, without violating causality. We illuminate the
important role played by unstable modes in this propagation, and show that the
quantum fluctuations of these modes, and their unitary time evolution, impose
severe restrictions on the observation of superluminal phenomena.
| [
{
"version": "v1",
"created": "Tue, 7 Apr 1998 11:26:29 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Aharonov",
"Yakir",
"",
"Tel-Aviv and South Carolina"
],
[
"Reznik",
"Benni",
"",
"Los Alamos"
],
[
"Stern",
"Ady",
"",
"Weizmann"
]
] |
quant-ph/9804019 | Comman area for Thpd | Arun Kumar Pati (Theory Phys Div., B.A.R.C., Mumbai, India) | Observability of relative phases of macroscopic quantum states | Latex file, no figures, 12 pages, submitted to Phys. Lett.A | null | null | null | quant-ph | null | After a measurement, to observe the relative phases of macroscopically
distinguishable states we have to ``undo'' a quantum measurement. We generalise
an earlier model of Peres from two state to N-state quantum system undergoing
measurement process and discuss the issue of observing relative phases of
different branches. We derive an inequality which is satisfied by the relative
phases of macroscopically distinguishable states and consequently any desired
relative phases can not be observed in interference setups. The principle of
macroscopic complementarity is invoked that might be at ease with the
macroscopic world. We illustrate the idea of limit on phase observability in
Stern-Gerlach measurements and the implications are discussed.
| [
{
"version": "v1",
"created": "Wed, 8 Apr 1998 06:44:43 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Pati",
"Arun Kumar",
"",
"Theory Phys Div., B.A.R.C., Mumbai, India"
]
] |
quant-ph/9804020 | I. Rotter | C. Jung, M. Mueller and I. Rotter | Phase transitions in open quantum systems | 28 pages, 22 Postscript figures | Phys.Rev. E60 (1999) 114-131 | 10.1103/PhysRevE.60.114 | null | quant-ph | null | We consider the behaviour of open quantum systems in dependence on the
coupling to one decay channel by introducing the coupling parameter $\alpha$
being proportional to the average degree of overlapping. Under critical
conditions, a reorganization of the spectrum takes place which creates a
bifurcation of the time scales with respect to the lifetimes of the resonance
states. We derive analytically the conditions under which the reorganization
process can be understood as a second-order phase transition and illustrate our
results by numerical investigations. The conditions are fulfilled e.g. for a
picket fence with equal coupling of the states to the continuum. Energy
dependencies within the system are included. We consider also the generic case
of an unfolded Gaussian Orthogonal Ensemble. In all these cases, the
reorganization of the spectrum occurs at the critical value $\alpha_{crit}$ of
the control parameter globally over the whole energy range of the spectrum. All
states act cooperatively.
| [
{
"version": "v1",
"created": "Wed, 8 Apr 1998 10:44:41 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Jung",
"C.",
""
],
[
"Mueller",
"M.",
""
],
[
"Rotter",
"I.",
""
]
] |
quant-ph/9804021 | Giacomo Mauro D'Ariano | G.M.D'Ariano, C. Macchiavello, L.Maccone (Dipartimento di Fisica ``A.
Volta'', Pavia, Italy) | Quantum tomography of mesoscopic superpositions of radiation states | Submitted to Phys. Rev. Lett.; 4 pages including 6 ps figures | Phys.Rev.A59:1816,1999 | 10.1103/PhysRevA.59.1816 | null | quant-ph | null | We show the feasibility of a tomographic reconstruction of Schr\"{o}dinger
cat states generated according to the scheme proposed by S. Song, C.M. Caves
and B. Yurke [Phys. Rev. A 41, 5261 (1990)]. We present a technique that
tolerates realistic values for quantum efficiency at photodetectors. The
measurement can be achieved by a standard experimental setup.
| [
{
"version": "v1",
"created": "Wed, 8 Apr 1998 18:09:07 GMT"
}
] | 2011-05-12T00:00:00 | [
[
"D'Ariano",
"G. M.",
"",
"Dipartimento di Fisica ``A.\n Volta'', Pavia, Italy"
],
[
"Macchiavello",
"C.",
"",
"Dipartimento di Fisica ``A.\n Volta'', Pavia, Italy"
],
[
"Maccone",
"L.",
"",
"Dipartimento di Fisica ``A.\n Volta'', Pavia, Italy"
]
] |
quant-ph/9804022 | Carsten Henkel | Carsten Henkel and Jean-Yves Courtois (Institut d'Optique, Orsay,
France) | Recoil and momentum diffusion of an atom close to a vacuum-dielectric
interface | submitted to European Physical Journal D (26 pages, 8 figures, uses
epsf.sty) | Eur. Phys. J. D 3 (1998) 129-153 | 10.1007/s100530050157 | null | quant-ph | null | We derive the quantum-mechanical master equation (generalized optical Bloch
equation) for an atom in the vicinity of a flat dielectric surface. This
equation gives access to the semiclassical radiation pressure force and the
atomic momentum diffusion tensor, that are expressed in terms of the vacuum
field correlation function (electromagnetic field susceptibility). It is
demonstrated that the atomic center-of-mass motion provides a nonlocal probe of
the electromagnetic vacuum fluctuations. We show in particular that in a
circularly polarized evanescent wave, the radiation pressure force experienced
by the atoms is not colinear with the evanescent wave's propagation vector. In
a linearly polarized evanescent wave, the recoil per fluorescence cycle leads
to a net magnetization for a Jg = 1/2 ground state atom.
| [
{
"version": "v1",
"created": "Thu, 9 Apr 1998 10:22:19 GMT"
}
] | 2021-08-06T00:00:00 | [
[
"Henkel",
"Carsten",
"",
"Institut d'Optique, Orsay,\n France"
],
[
"Courtois",
"Jean-Yves",
"",
"Institut d'Optique, Orsay,\n France"
]
] |
quant-ph/9804023 | David Meyer | David A. Meyer (University of California/San Diego) | Decoherence in the Dirac equation | 8 pages, plain TeX, 6 PostScript figures included with epsf.tex
(ignore the under/overfull \vbox error messages) | null | null | null | quant-ph | null | A Dirac particle is represented by a unitarily evolving state vector in a
Hilbert space which factors as $H_{spin} \otimes H_{position}$. Motivated by
the similarity to simple models of decoherence consisting of a two state system
coupled to an environment, we investigate the occurence of decoherence in the
Dirac equation upon tracing over position. We conclude that the physics of this
mathematically exact model for decoherence is closely related to
Zitterbewegung.
| [
{
"version": "v1",
"created": "Thu, 9 Apr 1998 19:12:13 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Meyer",
"David A.",
"",
"University of California/San Diego"
]
] |
quant-ph/9804024 | Karol Zyczkowski | Karol Zyczkowski (Krakow), Pawel Horodecki (Gdansk), Anna Sanpera and
Maciej Lewenstein (Saclay) | On the volume of the set of mixed entangled states | 10 pages in LaTex - RevTex + 4 figures in eps. submitted to Phys.
Rev. A | Phys.Rev. A58 (1998) 883 | 10.1103/PhysRevA.58.883 | null | quant-ph | null | A natural measure in the space of density matrices describing N-dimensional
quantum systems is proposed. We study the probability P that a quantum state
chosen randomly with respect to the natural measure is not entangled (is
separable). We find analytical lower and upper bounds for this quantity.
Numerical calculations give P = 0.632 for N=4 and P=0.384 for N=6, and indicate
that P decreases exponentially with N. Analysis of a conditional measure of
separability under the condition of fixed purity shows a clear dualism between
purity and separability: entanglement is typical for pure states, while
separability is connected with quantum mixtures. In particular, states of
sufficiently low purity are necessarily separable.
| [
{
"version": "v1",
"created": "Thu, 9 Apr 1998 21:17:21 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Zyczkowski",
"Karol",
"",
"Krakow"
],
[
"Horodecki",
"Pawel",
"",
"Gdansk"
],
[
"Sanpera",
"Anna",
"",
"Saclay"
],
[
"Lewenstein",
"Maciej",
"",
"Saclay"
]
] |
quant-ph/9804025 | Phil Gossett | Phil Gossett | NP in BQP with Nonlinearity | 8 pages, no figures, several bugs fixed, added GR nonlinearity
mechanism | null | null | SGI-98-5433-1c | quant-ph | null | If one modifies the laws of Quantum Mechanics to allow nonlinear evolution of
quantum states, this paper shows that NP-complete problems would be efficiently
solvable in polynomial time with bounded probability (NP in BQP). With that
(admittedly very unlikely) assumption, this is demonstrated by describing a
polynomially large network of quantum gates that solves the 3SAT problem with
bounded probability in polynomial time. As in a previous paper by Abrams and
Lloyd (but by a somewhat simpler argument), allowing nonlinearity in the laws
of Quantum Mechanics would prove the "weak Church-Turing thesis" to be false.
General Relativity is suggested as a possible mechanism to supply the necessary
nonlinearity.
| [
{
"version": "v1",
"created": "Thu, 9 Apr 1998 21:46:29 GMT"
},
{
"version": "v2",
"created": "Mon, 13 Apr 1998 16:12:36 GMT"
},
{
"version": "v3",
"created": "Mon, 27 Apr 1998 17:41:30 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gossett",
"Phil",
""
]
] |
quant-ph/9804026 | Akira Shimizu | Akira Shimizu and Kazuko Fujita (University of Tokyo) | First-kind measurements, non-demolition measurements, and conservation
laws | 7 pages including 1 figure. A typo (of the book version and the
previous quant-ph version) in Eq. (9) has been fixed. Figure 1 has been
included in the manuscript. Style parameters have been adjusted to fit both
the A4 and US letter papers | Quantum Control and Measurement, H. Ezawa and Y. Murayama, eds.,
North-Holland, Amsterdam (1993) pp. 191-196 | null | null | quant-ph | null | A general discussion is given for first-kind (FK) and quantum non-demolition
(QND) measurements. The general conditions for these measurements are derived,
including the most general one (called the weak condition), an intermediate
one, and the strongest one. The weak condition indicates that we can realize a
FK or QND measuring apparatus of wide classes of observables by allowing the
apparatus to have a finite response range. A recently-proposed QND
photodetector using an electron interferometer is an example of such apparatus.
| [
{
"version": "v1",
"created": "Sat, 11 Apr 1998 05:31:22 GMT"
},
{
"version": "v2",
"created": "Mon, 7 Jun 1999 09:51:23 GMT"
},
{
"version": "v3",
"created": "Tue, 8 Jun 1999 01:19:29 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Shimizu",
"Akira",
"",
"University of Tokyo"
],
[
"Fujita",
"Kazuko",
"",
"University of Tokyo"
]
] |
quant-ph/9804027 | Akira Shimizu | Akira Shimizu | Quantum Measurement and Fluctuations in Nanostructures | 14 pages, 2 figures | Nanostructures and Quantum Effects, eds. H. Sakaki and H. Noge
(Springer Verlag, Heidelberg, 1994) 35-47 | null | null | quant-ph cond-mat.mes-hall physics.optics | null | Measurement and fluctuations are closely related to each other in quantum
mechanics. This fact is explicitly demonstrated in the case of a quantum
non-demolition photodetector which is composed of a double quantum-wire
electron interferometer.
| [
{
"version": "v1",
"created": "Sat, 11 Apr 1998 06:26:54 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Shimizu",
"Akira",
""
]
] |
quant-ph/9804028 | Akira Shimizu | Akira Shimizu, Teruaki Okushima and Kazuki Koshino | Quantum Optics in Dispersive and Absorptive Media | 8 pages, 3 figures Proc. 6th NEC Symposium on Fundamental Approaches
to New Material Phases (Karuizawa, Japan 1996) | Mater.Sci.Eng.B48:66-70,1997 | null | null | quant-ph cond-mat.mtrl-sci physics.optics | null | Using microscopic models in which both photons and excitons are treated as
microscopic degrees of freedom, we discuss polaritons of two cases: One is the
case when excitonic parameters are time dependent. The time dependence causes
creation of polaritons from a "false vacuum." % We present the creation spectra
of both % the lower- and upper-branch polaritons. It is shown that both the
creation sepctra and the creation efficiency are much different from the
results of the previous studies. The other is polaritons in absorptive and
inhomogeneous cavities. A polariton in such a system cannot be viewed as a back
and forth oscillation between a photon state and an exciton state.
| [
{
"version": "v1",
"created": "Sat, 11 Apr 1998 07:37:49 GMT"
}
] | 2011-04-15T00:00:00 | [
[
"Shimizu",
"Akira",
""
],
[
"Okushima",
"Teruaki",
""
],
[
"Koshino",
"Kazuki",
""
]
] |
quant-ph/9804029 | Akira Shimizu | Akira Shimizu and Masamichi Yamanishi | Photon-energy dissipation caused by an external electric circuit in
"virtual" photo-excitation processes | 4 pages, 1 fugure | Phys.Rev.Lett. 72 (1994) 3343-3346 | 10.1103/PhysRevLett.72.3343 | null | quant-ph cond-mat.mtrl-sci physics.optics | null | We consider generation of an electrical pulse by an optical pulse in the
``virtual excitation'' regime. The electronic system, which is any
electro-optic material including a quantum well structure biased by a dc
electric field, is assumed to be coupled to an external circuit. It is found
that the photon frequency is subject to an extra red shift in addition to the
usual self-phase modulation, whereas the photon number is conserved. The Joule
energy consumed in the external circuit is supplied only from the extra red
shift.
| [
{
"version": "v1",
"created": "Sat, 11 Apr 1998 10:29:08 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Shimizu",
"Akira",
""
],
[
"Yamanishi",
"Masamichi",
""
]
] |
quant-ph/9804030 | Carbonell | M. Mangin-Brinet, J. Carbonell and C. Gignoux | Exact boundary conditions at finite distance for the time-dependent
Schrodinger equation | Latex.tar.gz file, 20 pages, 9 figures | null | 10.1103/PhysRevA.57.3245 | null | quant-ph | null | Exact boundary conditions at finite distance for the solutions of the
time-dependent Schrodinger equation are derived. A numerical scheme based on
Crank-Nicholson method is proposed to illustrate its applicability in several
examples.
| [
{
"version": "v1",
"created": "Sat, 11 Apr 1998 15:17:03 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Mangin-Brinet",
"M.",
""
],
[
"Carbonell",
"J.",
""
],
[
"Gignoux",
"C.",
""
]
] |
quant-ph/9804031 | Asher Peres | Asher Peres and Daniel Terno | Optimal distinction between non-orthogonal quantum states | 9 pages LaTeX, one PostScript figure on separate page | J.Phys.A31:7105-7112,1998 | 10.1088/0305-4470/31/34/013 | null | quant-ph | null | Given a finite set of linearly independent quantum states, an observer who
examines a single quantum system may sometimes identify its state with
certainty. However, unless these quantum states are orthogonal, there is a
finite probability of failure. A complete solution is given to the problem of
optimal distinction of three states, having arbitrary prior probabilities and
arbitrary detection values. A generalization to more than three states is
outlined.
| [
{
"version": "v1",
"created": "Sun, 12 Apr 1998 07:22:03 GMT"
}
] | 2009-09-25T00:00:00 | [
[
"Peres",
"Asher",
""
],
[
"Terno",
"Daniel",
""
]
] |
quant-ph/9804032 | Boris F. Samsonov | Vladislav G. Bagrov, Boris F. Samsonov and L. A. Shekoyan | N-order Darboux transformation and a spectral problem on semiaxis | null | null | null | null | quant-ph | null | N-order Darboux transformation operator is defined on the basis of a general
notion of transformation operators. Factorisation properties of this operator
are studied. The Darboux transformation operator technique is applied to
construct and investigate potentials with bound states at arbitrary energies
for the spectral problem on semiaxis.
| [
{
"version": "v1",
"created": "Mon, 13 Apr 1998 04:50:15 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Bagrov",
"Vladislav G.",
""
],
[
"Samsonov",
"Boris F.",
""
],
[
"Shekoyan",
"L. A.",
""
]
] |
quant-ph/9804033 | Andrea Nemes Salgueiro | K. Fonseca Romero (1), M. C. Nemes (2), J. G. Peixoto de Faria (2), A.
N. Salgueiro (1), A. F. R. de Toledo Piza (1) ((1) Instituto de Fisica,
Universidade de Sao Paulo (USP); (2) Departamento de Fisica, Univesidade
federal de Minas Gerais (UFMG), Brazil) | Decoherence of mesoscopic states of cavity fields | quantum physics | null | 10.1103/PhysRevA.58.3205 | 1305 | quant-ph | null | We show that two-atom correlation measurements of the type involved in a
recent experimental study of the evolution of a mesoscopic superposition state
prepared in a definite mode of a high-Q cavity can be used to determine the
eigenvalues of the reduced density matrix of the field, provided the assumed
dynamical conditions are actually fulfilled to experimental accuracy. These
conditions involve i) a purely dispersive coupling of the field to the Rydberg
atoms used to manipulate and to monitor the cavity field, and ii) the effective
absence of correlations in the ground state of the system consisting of the
cavity coupled to the ``reservoir'' which accounts for the decoherence and
damping processes. A microscopic calculation at zero temperature is performed
and compared to master equation results.
| [
{
"version": "v1",
"created": "Tue, 14 Apr 1998 19:37:03 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Romero",
"K. Fonseca",
""
],
[
"Nemes",
"M. C.",
""
],
[
"de Faria",
"J. G. Peixoto",
""
],
[
"Salgueiro",
"A. N.",
""
],
[
"Piza",
"A. F. R. de Toledo",
""
]
] |
quant-ph/9804034 | Cristopher Moore | Cristopher Moore and Martin Nilsson | Some Notes on Parallel Quantum Computation | null | null | null | null | quant-ph | null | We exhibit some simple gadgets useful in designing shallow parallel circuits
for quantum algorithms. We prove that any quantum circuit composed entirely of
controlled-not gates or of diagonal gates can be parallelized to logarithmic
depth, while circuits composed of both cannot. Finally, while we note the
Quantum Fourier Transform can be parallelized to linear depth, we exhibit a
simple quantum circuit related to it that we believe cannot be parallelized to
less than linear depth, and therefore might be used to prove that QNC < QP.
| [
{
"version": "v1",
"created": "Tue, 14 Apr 1998 20:10:45 GMT"
},
{
"version": "v2",
"created": "Wed, 29 Apr 1998 17:41:14 GMT"
}
] | 2009-09-25T00:00:00 | [
[
"Moore",
"Cristopher",
""
],
[
"Nilsson",
"Martin",
""
]
] |
quant-ph/9804035 | James Anglin | J.R. Anglin and W.H. Zurek | Winding up by a quench: vortices in the wake of rapid Bose-Einstein
condensation | 4 pages, 2 figures; misprint corrected | Phys.Rev.Lett. 83 (1999) 1707-1710 | 10.1103/PhysRevLett.83.1707 | wbq-1 | quant-ph cond-mat hep-ph | null | A second order phase transition induced by a rapid quench can lock out
topological defects with densities far exceeding their equilibrium expectation
values. We use quantum kinetic theory to show that this mechanism, originally
postulated in the cosmological context, and analysed so far only on the mean
field classical level, should allow spontaneous generation of vortex lines in
trapped Bose-Einstein condensates of simple topology, or of winding number in
toroidal condensates.
| [
{
"version": "v1",
"created": "Tue, 14 Apr 1998 23:51:28 GMT"
},
{
"version": "v2",
"created": "Thu, 30 Apr 1998 18:09:15 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Anglin",
"J. R.",
""
],
[
"Zurek",
"W. H.",
""
]
] |
quant-ph/9804036 | Shigeru Furuichi | Shigeru Furuichi, Masanori Ohya and Hiroki Suyari | Quantum mutual entropy for Jaynes-Cummings model | RevTeX, 4 pages with a figure(eps file), submitted to Physical Review
Letters | Rept.Math.Phys.44:81-86,1999 | 10.1016/S0034-4877(99)80147-5 | null | quant-ph | null | The dynamics of an atom on the Jaynes-Cummings model has been studied by an
atomic inversion, von Neumann entropy and so on. In this letter, we will treat
the Jaynes-Cummings model as a problem in non-equilibrium statistical mechanics
and apply quantum mutual entropy to study the irreversible dynamics of a state
for the atom on this model.
| [
{
"version": "v1",
"created": "Wed, 15 Apr 1998 03:48:34 GMT"
}
] | 2011-04-15T00:00:00 | [
[
"Furuichi",
"Shigeru",
""
],
[
"Ohya",
"Masanori",
""
],
[
"Suyari",
"Hiroki",
""
]
] |
quant-ph/9804037 | Dr A. K. Kapoor | A.K.Kapoor and Pankaj Sharan | Hamiltonian path integral quantization in polar coordinates | 15 pages, latex, no figures | null | null | null | quant-ph | null | Using a scheme proposed earlier we set up Hamiltonian path integral
quantization for a particle in two dimensions in plane polar coordinates.This
scheme uses the classical Hamiltonian, without any $O(\hbar^2)$ terms, in the
polar varivables. We show that the propagator satisfies the correct
Schr\"{o}dinger equation.
| [
{
"version": "v1",
"created": "Wed, 15 Apr 1998 10:37:07 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kapoor",
"A. K.",
""
],
[
"Sharan",
"Pankaj",
""
]
] |
quant-ph/9804038 | Kevin M. Obenland | Kevin M. Obenland and Alvin M. Despain | Simulating the Effect of Decoherence and Inaccuracies on a Quantum
Computer | 12 pages, Presented at the 1st NASA conference on Quantum Computing
and Quantum Communication | null | null | null | quant-ph | null | A Quantum Computer is a new type of computer which can solve problems such as
factoring and database search very efficiently. The usefulness of a quantum
computer is limited by the effect of two different types of errors, decoherence
and inaccuracies. In this paper we show the results of simulations of a quantum
computer which consider both decoherence and inaccuracies. We simulate circuits
which factor the numbers 15, 21, 35, and 57 as well as circuits which use
database search to solve the circuit satisfaction problem. Our simulations show
that the error rate per gate is on the order of 10^-6 for a trapped ion quantum
computer whose noise is kept below pi/4096 per gate and with a decoherence rate
of 10^-6. This is an important bound because previous studies have shown that a
quantum computer can factor more efficiently than a classical computer if the
error rate is of order 10^-6.
| [
{
"version": "v1",
"created": "Thu, 16 Apr 1998 02:31:14 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Obenland",
"Kevin M.",
""
],
[
"Despain",
"Alvin M.",
""
]
] |
quant-ph/9804039 | Kevin M. Obenland | Kevin M. Obenland and Alvin M. Despain | A Parallel Quantum Computer Simulator | 22 pages, Presented at High Performance Computing 1998 | null | null | null | quant-ph | null | A Quantum Computer is a new type of computer which can efficiently solve
complex problems such as prime factorization. A quantum computer threatens the
security of public key encryption systems because these systems rely on the
fact that prime factorization is computationally difficult. Errors limit the
effectiveness of quantum computers. Because of the exponential nature of
quantum com puters, simulating the effect of errors on them requires a vast
amount of processing and memory resources. In this paper we describe a parallel
simulator which accesses the feasibility of quantum computers. We also derive
and validate an analytical model of execution time for the simulator, which
shows that parallel quantum computer simulation is very scalable.
| [
{
"version": "v1",
"created": "Thu, 16 Apr 1998 02:40:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Obenland",
"Kevin M.",
""
],
[
"Despain",
"Alvin M.",
""
]
] |
quant-ph/9804040 | Luigi Foschini | Luigi Foschini | On the logic of quantum physics and the concept of the time | 21 pages, no figures. Revised version, merged with quant-ph/9901013.
Title is changed | null | null | null | quant-ph | null | The logic--linguistic structure of quantum physics is analysed. The role of
formal systems and interpretations in the representation of nature is
investigated. The problems of decidability, completeness, and consistency can
affect quantum physics in different ways. Bohr's complementarity is of great
interest,because it is a contradictory proposition. We shall see that the
flowing of time prevents the birth of contradictions in nature, because it
makes a cut between two different, but complementary aspects of the reality.
| [
{
"version": "v1",
"created": "Thu, 16 Apr 1998 15:10:54 GMT"
},
{
"version": "v2",
"created": "Tue, 5 May 1998 10:31:18 GMT"
},
{
"version": "v3",
"created": "Tue, 21 Jul 1998 14:05:44 GMT"
},
{
"version": "v4",
"created": "Sun, 16 Dec 2001 10:54:39 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Foschini",
"Luigi",
""
]
] |
quant-ph/9804041 | Jose L. Mateos | G. Garcia-Calderon, J. L. Mateos and M. Moshinsky (Instituto de
Fisica, UNAM, Mexico) | Reply to the Comment on "Resonant Spectra and the Time Evolution of the
Survival and Nonescape Probabilities" | 1 page, RevTex file, to appear in Phys. Rev. Lett | Phys.Rev.Lett. 80 (1998) 4354 | 10.1103/PhysRevLett.80.4354 | IFUNAM-SC98-04 | quant-ph | null | In our paper [Phys. Rev. Lett. 74, 337 (1995)], we derived an exact
expression for the survival and nonescape probabilities as an expansion in
terms of resonant states. It was shown that these quantities exhibit at long
times a different behavior. Although both decay as a power law, they have
different exponents. In this paper we show that, contrary to the claim in the
Comment of R. M. Cavalcanti (quant-ph/9704023), the nonescape probability decay
for long times as an inverse power law.
| [
{
"version": "v1",
"created": "Fri, 17 Apr 1998 00:08:28 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Garcia-Calderon",
"G.",
"",
"Instituto de\n Fisica, UNAM, Mexico"
],
[
"Mateos",
"J. L.",
"",
"Instituto de\n Fisica, UNAM, Mexico"
],
[
"Moshinsky",
"M.",
"",
"Instituto de\n Fisica, UNAM, Mexico"
]
] |
quant-ph/9804042 | Matrasulov Davron | D.Matrasulov | Wave Functions and Energy Terms of the SCHR\"Odinger Equation with
Two-Center Coulomb Plus Harmonic Oscillator Potential | 4 pages, no figures, LaTeX, submitted to PRL | null | 10.1007/BF02557178 | null | quant-ph | null | Schr\"odinger equation for two center Coulomb plus harmonic oscillator
potential is solved by the method of ethalon equation at large intercenter
separations. Asymptotical expansions for energy term and wave function are
obtained in the analytical form.
| [
{
"version": "v1",
"created": "Fri, 17 Apr 1998 05:27:53 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Matrasulov",
"D.",
""
]
] |
quant-ph/9804043 | Ashwin Nayak | Andris Ambainis, Ashwin Nayak, Amnon Ta-Shma, Umesh Vazirani | Dense Quantum Coding and a Lower Bound for 1-way Quantum Automata | 12 pages, 3 figures. Defines random access codes, gives upper and
lower bounds for the number of bits required for such (possibly quantum)
codes. Derives the size lower bound for quantum finite automata of the
earlier version of the paper using these results | null | null | null | quant-ph cs.CC | null | We consider the possibility of encoding m classical bits into much fewer n
quantum bits so that an arbitrary bit from the original m bits can be recovered
with a good probability, and we show that non-trivial quantum encodings exist
that have no classical counterparts. On the other hand, we show that quantum
encodings cannot be much more succint as compared to classical encodings, and
we provide a lower bound on such quantum encodings. Finally, using this lower
bound, we prove an exponential lower bound on the size of 1-way quantum finite
automata for a family of languages accepted by linear sized deterministic
finite automata.
| [
{
"version": "v1",
"created": "Sat, 18 Apr 1998 00:39:22 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Nov 1998 03:06:13 GMT"
}
] | 2019-08-17T00:00:00 | [
[
"Ambainis",
"Andris",
""
],
[
"Nayak",
"Ashwin",
""
],
[
"Ta-Shma",
"Amnon",
""
],
[
"Vazirani",
"Umesh",
""
]
] |
quant-ph/9804044 | Valerio Scarani | Valerio Scarani (EPF Lausanne) | Quantum Computing | 10 pages, 0 figures; didactic review; Am.J.Phys. 66, Nov. 98,
956-960, with updated references | null | 10.1119/1.19005 | VS-97-02 | quant-ph | null | The main features of quantum computing are described in the framework of spin
resonance methods. Stress is put on the fact that quantum computing is in
itself nothing but a re-interpretation (fruitful indeed) of well-known
concepts. The role of the two basic operations, one-spin rotation and
controlled-NOT gates, is analyzed, and some exercises are proposed.
| [
{
"version": "v1",
"created": "Mon, 20 Apr 1998 07:27:35 GMT"
},
{
"version": "v2",
"created": "Tue, 6 Oct 1998 07:04:59 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Scarani",
"Valerio",
"",
"EPF Lausanne"
]
] |
quant-ph/9804045 | Nicolas Gisin | N. Gisin and H. Bechmann-Pasquinucci | Bell inequality, Bell states and maximally entangled states for n qubits | 8 pages, no figure | Phys.Lett. A246 (1998) 1-6 | 10.1016/S0375-9601(98)00516-7 | null | quant-ph | null | First, we present a Bell type inequality for n qubits, assuming that m out of
the n qubits are independent. Quantum mechanics violates this inequality by a
ratio that increases exponentially with m. Hence an experiment on n qubits
violating of this inequality sets a lower bound on the number m of entangled
qubits. Next, we propose a definition of maximally entangled states of n
qubits. For this purpose we study 5 different criteria. Four of these criteria
are found compatible. For any number n of qubits, they determine an orthogonal
basis consisting of maximally entangled states generalizing the Bell states.
| [
{
"version": "v1",
"created": "Mon, 20 Apr 1998 09:18:42 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Gisin",
"N.",
""
],
[
"Bechmann-Pasquinucci",
"H.",
""
]
] |
quant-ph/9804046 | null | M. Daoud, Y. Hassouni and M. Kibler | On Generalized Super-Coherent States | 9 pages, Latex file. Submitted for publication to Yadernaya Fizika
(Russian Journal of Nuclear Physics) | Phys.Atom.Nucl.61:1821-1824,1998; Yad.Fiz.61:1935-1938,1998 | null | null | quant-ph hep-th math-ph math.MP math.QA | null | A set of operators, the so-called k-fermion operators, that interpolate
between boson and fermion operators are introduced through the consideration of
an algebra arising from two non-commuting quon algebras. The deformation
parameters q and 1/q for these quon algebras are roots of unity with q to the
power k being equal to 1. The case k = 2 corresponds to fermions and the case k
going to infinity to bosons. Generalized coherent states (connected to the
k-fermionic states) and super-coherent states (involving a k-fermionic sector
and a purely bosonic sector) are investigated.
| [
{
"version": "v1",
"created": "Mon, 20 Apr 1998 12:45:55 GMT"
}
] | 2011-04-15T00:00:00 | [
[
"Daoud",
"M.",
""
],
[
"Hassouni",
"Y.",
""
],
[
"Kibler",
"M.",
""
]
] |
quant-ph/9804047 | Subhash Kak | Subhash Kak | Quantum Information in a Distributed Apparatus | 10 pages | Found.Phys.28:1005-1012,1998 | 10.1023/A:1018877532212 | ECE 96-12 | quant-ph | null | We investigate the information provided about a specified distributed
apparatus of n units in the measurement of a quantum state. It is shown that,
in contrast to such measurement of a classical state, which is bounded by log
(n+1) bits, the information in a quantum measurement is bounded by 3.7 x
n^(1/2) bits. This means that the use of quantum apparatus offers an
exponential advantage over classical apparatus.
| [
{
"version": "v1",
"created": "Mon, 20 Apr 1998 16:13:47 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Kak",
"Subhash",
""
]
] |
quant-ph/9804048 | Daniel F. V. James | Daniel F. V. James (Los Alamos National Laboratory) | The theory of heating of the quantum ground state of trapped ions | 9 pages, 2 figures | Phys.Rev.Lett. 81 (1998) 317-320 | 10.1103/PhysRevLett.81.317 | LA-UR 98-654 | quant-ph | null | Using a displacement operator formalism, I analyse the depopulation of the
vibrational ground state of trapped ions. Two heating times, one characterizing
short time behaviour, the other long time behaviour are found. The short time
behaviour is analyzed both for single and multiple ions, and a formula for the
relative heating rates of different modes is derived. The possibility of
correction of heating via the quantum Zeno effect, and the exploitation of the
suppression of heating of higher modes to reduce errors in quantum computation
is considered.
| [
{
"version": "v1",
"created": "Mon, 20 Apr 1998 17:56:59 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"James",
"Daniel F. V.",
"",
"Los Alamos National Laboratory"
]
] |
quant-ph/9804049 | John Klauder | John R. Klauder and Sergei V. Shabanov | An Introduction to Coordinate-free Quantization and its Application to
Constrained Systems | 12 pages, LaTeX, no figures | null | null | null | quant-ph hep-th math-ph math.MP | null | Canonical quantization entails using Cartesian coordinates, and Cartesian
coordinates exist only in flat spaces. This situation can either be questioned
or accepted. In this paper we offer a brief and introductory overview of how a
flat phase space metric can be incorporated into a covariant, coordinate-free
quantization procedure involving a continuous-time (Wiener measure)
regularization of traditional phase space path integrals. Additionally we show
how such procedures can be extended to incorporate systems with constraints and
illustrate that extension for special systems.
| [
{
"version": "v1",
"created": "Tue, 21 Apr 1998 17:30:22 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Klauder",
"John R.",
""
],
[
"Shabanov",
"Sergei V.",
""
]
] |
quant-ph/9804050 | Konrad Banaszek | Konrad Banaszek (Uniwersytet Warszawski) | Reconstruction of photon distribution with positivity constraints | 6 pages, LaTeX. Submitted to Special Issue of Acta Physica Slovaca on
Quantum Optics and Quantum Information | Acta Phys.Slov. 48 (1998) 185-190 | null | null | quant-ph | null | An iterative algorithm for reconstructing the photon distribution from the
random phase homodyne statistics is discussed. This method, derived from the
maximum-likelihood approach, yields a positive definite estimate for the photon
distribution with bounded statistical errors even if numerical compensation for
the detector imperfection is applied.
| [
{
"version": "v1",
"created": "Wed, 22 Apr 1998 12:28:30 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Banaszek",
"Konrad",
"",
"Uniwersytet Warszawski"
]
] |
quant-ph/9804051 | Hiroshi Fujisaki | Hiroshi Fujisaki and Akira Shimizu | Quantum Langevin equations for semiconductor light-emitting devices and
the photon statistics at a low-injection level | 10 pages, 8 figures | Phys.Rev. A57 (1998) 3074 | 10.1103/PhysRevA.57.3074 | null | quant-ph | null | From the microscopic quantum Langevin equations (QLEs) we derive the
effective semiconductor QLEs and the associated noise correlations which are
valid at a low-injection level and in real devices. Applying the semiconductor
QLEs to semiconductor light-emitting devices (LEDs), we obtain a new formula
for the Fano factor of photons which gives the photon-number statistics as a
function of the pump statistics and several parameters of LEDs. Key ingredients
are non-radiative processes, carrier-number dependence of the radiative and
non-radiative lifetimes, and multimodeness of LEDs. The formula is applicable
to the actual cases where the quantum efficiency $\eta$ differs from the
differential quantum efficiency $\eta_{d}$, whereas previous theories
implicitly assumed $\eta = \eta_{d}$. It is also applicable to the cases when
photons in each mode of the cavity are emitted and/or detected inhomogeneously.
When $\eta_{d} < \eta$ at a running point, in particular, our formula predicts
that even a Poissonian pump can produce sub-Poissonian light. This mechanism
for generation of sub-Poissonian light is completely different from those of
previous theories, which assumed sub-Poissonian statistics for the current
injected into the active layers of LEDs. Our results agree with recent
experiments. We also discuss frequency dependence of the photon statistics.
| [
{
"version": "v1",
"created": "Wed, 22 Apr 1998 12:32:42 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Fujisaki",
"Hiroshi",
""
],
[
"Shimizu",
"Akira",
""
]
] |
quant-ph/9804052 | M. Czachor | Sergei B. Leble and Marek Czachor (Politechnika Gdanska) | Darboux-integrable nonlinear Liouville-von Neumann equation | Explicit examples added (harmonic oscillator, two spin-1/2 particles,
matrix Hamiltonians,...) | Phys.Rev. E58 (1998) 7091-7100 | 10.1103/PhysRevE.58.7091 | null | quant-ph math-ph math.MP nlin.SI solv-int | null | A new form of a binary Darboux transformation is used to generate analytical
solutions of a nonlinear Liouville-von Neumann equation. General theory is
illustrated by explicit examples.
| [
{
"version": "v1",
"created": "Wed, 22 Apr 1998 13:58:21 GMT"
},
{
"version": "v2",
"created": "Mon, 4 May 1998 10:35:59 GMT"
},
{
"version": "v3",
"created": "Fri, 12 Jun 1998 09:05:39 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Leble",
"Sergei B.",
"",
"Politechnika Gdanska"
],
[
"Czachor",
"Marek",
"",
"Politechnika Gdanska"
]
] |
quant-ph/9804053 | David DiVincenzo | Charles H. Bennett (1), David P. DiVincenzo (1), Christopher A. Fuchs
(2), Tal Mor (3), Eric Rains (4), Peter W. Shor (4), John A. Smolin (1),
William K. Wootters (5) ((1) IBM, (2) Cal Tech, (3) U. Montreal, (4) AT&T,
(5) Williams) | Quantum Nonlocality without Entanglement | 27 pages, Latex, 6 ps figures. To be submitted to Phys. Rev. A.
Version 2: 30 pages, many small revisions and extensions, author added.
Version 3: Proof in Appendix D corrected, many small changes; final version
for Phys. Rev. A Version 4: Report of Popescu conjecture modified | null | 10.1103/PhysRevA.59.1070 | null | quant-ph cond-mat.mes-hall | null | We exhibit an orthogonal set of product states of two three-state particles
that nevertheless cannot be reliably distinguished by a pair of separated
observers ignorant of which of the states has been presented to them, even if
the observers are allowed any sequence of local operations and classical
communication between the separate observers. It is proved that there is a
finite gap between the mutual information obtainable by a joint measurement on
these states and a measurement in which only local actions are permitted. This
result implies the existence of separable superoperators that cannot be
implemented locally. A set of states are found involving three two-state
particles which also appear to be nonmeasurable locally. These and other
multipartite states are classified according to the entropy and entanglement
costs of preparing and measuring them by local operations.
| [
{
"version": "v1",
"created": "Wed, 22 Apr 1998 14:14:39 GMT"
},
{
"version": "v2",
"created": "Wed, 17 Jun 1998 14:52:38 GMT"
},
{
"version": "v3",
"created": "Mon, 28 Sep 1998 13:10:35 GMT"
},
{
"version": "v4",
"created": "Mon, 2 Nov 1998 17:02:40 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Bennett",
"Charles H.",
""
],
[
"DiVincenzo",
"David P.",
""
],
[
"Fuchs",
"Christopher A.",
""
],
[
"Mor",
"Tal",
""
],
[
"Rains",
"Eric",
""
],
[
"Shor",
"Peter W.",
""
],
[
"Smolin",
"John A.",
""
],
[
"Wootters",
"William K.",
""
]
] |
quant-ph/9804054 | Hans Thomas Elze | Hans-Thomas Elze | The Functional Derivation of Master Equations | 10 pages; LaTex. - Contribution to the workshop Hadron Physics VI,
March 1998, Florianopolis (Brazil); proceedings, E. Ferreira et al., eds.
(World Scientific). Replaced by slightly modified published version | Mod. Phys. Lett. A, Vol. 14, No. 32 (1999) pp. 2259-2267 | 10.1142/S0217732399002340 | null | quant-ph gr-qc nucl-th | null | Master equations describe the quantum dynamics of open systems interacting
with an environment. They play an increasingly important role in understanding
the emergence of semiclassical behavior and the generation of entropy, both
being related to quantum decoherence. Presently we derive the exact master
equation for a homogeneous scalar Higgs or inflaton like field coupled to an
environment field represented by an infinite set of harmonic oscillators. Our
aim is to demonstrate a derivation directly from the path integral
representation of the density matrix propagator. Applications and
generalizations of this result are discussed.
| [
{
"version": "v1",
"created": "Wed, 22 Apr 1998 17:29:46 GMT"
},
{
"version": "v2",
"created": "Thu, 30 Apr 1998 18:40:09 GMT"
},
{
"version": "v3",
"created": "Mon, 10 Jan 2000 20:35:15 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Elze",
"Hans-Thomas",
""
]
] |
quant-ph/9804055 | Larry Ford | L.H. Ford | Casimir Force between a Dielectric Sphere and a Wall: A Model for
Amplification of Vacuum Fluctuations | 18pp, LaTex, 7 figures, uses epsf. Several minor errors corrected,
additional comments added in the final two sections, and references updated | Phys. Rev. A, 58 (1998) 4279 | 10.1103/PhysRevA.58.4279 | null | quant-ph cond-mat hep-th | null | The interaction between a polarizable particle and a reflecting wall is
examined. A macroscopic approach is adopted in which the averaged force is
computed from the Maxwell stress tensor. The particular case of a perfectly
reflecting wall and a sphere with a dielectric function given by the Drude
model is examined in detail. It is found that the force can be expressed as the
sum of a monotonically decaying function of position and of an oscillatory
piece. At large separations, the oscillatory piece is the dominant
contribution, and is much larger than the Casimir-Polder interaction that
arises in the limit that the sphere is a perfect conductor. It is argued that
this enhancement of the force can be interpreted in terms of the frequency
spectrum of vacuum fluctuations. In the limit of a perfectly conducting sphere,
there are cancellations between different parts of the spectrum which no longer
occur as completely in the case of a sphere with frequency dependent
polarizability. Estimates of the magnitude of the oscillatory component of the
force suggest that it may be large enough to be observable.
| [
{
"version": "v1",
"created": "Wed, 22 Apr 1998 20:16:22 GMT"
},
{
"version": "v2",
"created": "Thu, 22 Oct 1998 19:59:14 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Ford",
"L. H.",
""
]
] |
quant-ph/9804056 | Larry Ford | L.H. Ford and N.F. Svaiter | Vacuum Energy Density near Fluctuating Boundaries | 16pp, LaTex, 3 figures, uses epsf, Three references added and several
misprints corrected | Phys.Rev. D58 (1998) 065007 | 10.1103/PhysRevD.58.065007 | CBPF-NF/007/98 | quant-ph gr-qc hep-th | null | The imposition of boundary conditions upon a quantized field can lead to
singular energy densities on the boundary. We treat the boundaries as quantum
mechanical objects with a nonzero position uncertainty, and show that the
singular energy density is removed. This treatment also resolves a long
standing paradox concerning the total energy of the minimally coupled and
conformally coupled scalar fields.
| [
{
"version": "v1",
"created": "Thu, 23 Apr 1998 01:11:25 GMT"
},
{
"version": "v2",
"created": "Tue, 2 Jun 1998 21:41:48 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Ford",
"L. H.",
""
],
[
"Svaiter",
"N. F.",
""
]
] |
quant-ph/9804057 | Comman area for Thpd | Arun Kumar Pati (Theory Division, BARC, Mumbai, India) | Adiabatic Berry Phase and Hannay Angle for Open Paths | Latex, no figures, 24 pages, submitted to Ann. Phys | Annals Phys.270:178-197,1998 | 10.1006/aphy.1998.5850 | null | quant-ph | null | We obtain the adiabatic Berry phase by defining a generalised gauge potential
whose line integral gives the phase holonomy for arbitrary evolutions of
parameters. Keeping in mind that for classical integrable systems it is hardly
clear how to obtain open-path Hannay angle, we establish a connection between
the open-path Berry phase and Hannay angle by using the parametrised coherent
state approach. Using the semiclassical wavefunction we analyse the open-path
Berry phase and obtain the open-path Hannay angle. Further, by expressing the
adiabatic Berry phase in terms of the commutator of instantaneous projectors
with its differential and using Wigner representation of operators we obtain
the Poisson bracket between distribution function and its differential. This
enables us to talk about the classical limit of the phase holonomy which yields
the angle holonomy for open-paths. An operational definition of Hannay angle is
provided based on the idea of classical limit of quantum mechanical inner
product. A probable application of the open-path Berry phase and Hannay angle
to wave-packet revival phenomena is also pointed out.
| [
{
"version": "v1",
"created": "Thu, 23 Apr 1998 11:00:32 GMT"
}
] | 2011-07-19T00:00:00 | [
[
"Pati",
"Arun Kumar",
"",
"Theory Division, BARC, Mumbai, India"
]
] |
quant-ph/9804058 | Tamas Geszti | Tam\'as Geszti (Budapest) | Interaction-free measurement and forward scattering | 4 pages in RevTex + 1 figure in eps; submitted to Phys. Rev. A since
09Jan98; now updated | null | 10.1103/PhysRevA.58.4206 | null | quant-ph | null | Interaction-free measurement is shown to arise from the forward-scattered
wave accompanying absorption: a "quantum silhouette" of the absorber.
Accordingly, the process is not free of interaction. For a perfect absorber the
forward-scattered wave is locked both in amplitude and in phase. For an
imperfect one it has a nontrivial phase of dynamical origin (``colored
silhouette"), measurable by interferometry. Other examples of quantum
silhouettes, all controlled by unitarity, are briefly discussed.
| [
{
"version": "v1",
"created": "Thu, 23 Apr 1998 13:35:33 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Geszti",
"Tamás",
"",
"Budapest"
]
] |
quant-ph/9804059 | Kracklauer | A. F. Kracklauer | Skirting Hidden-Variable No-Go Theorems | 5 pages, RevTeX This revision includes one major conceptual addition
to Section IV: a novel semiclassical model of the EPR experiment. In
addition, many typos, glitches and expository defects were corrected | null | null | 20-4-98 | quant-ph | null | It is observed that the proofs of hidden-variable no-go theorems depend on
the `projection postulate,' which is seen to be contradictory with respect to
spin operators in directions orthogonal to the magnetic field direction. In
this light it is argued that it is less costly to abandon the projection
postulate than to abandon locality and this in turn renders Hidden-Variable
No-Go Theorems evadible. To buttress this point, a local realist model of the
EPR experiment which ignores the constraints of the projection postulate is
presented.
| [
{
"version": "v1",
"created": "Fri, 24 Apr 1998 13:50:15 GMT"
},
{
"version": "v2",
"created": "Fri, 2 Oct 1998 00:50:16 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kracklauer",
"A. F.",
""
]
] |
quant-ph/9804060 | Leonard J. Schulman | Leonard J. Schulman, Umesh Vazirani | Scalable NMR Quantum Computation | 16 pages, no figures. An updated "extended abstract" of this paper
appears in Proc. 31'st ACM STOC (Symp. Theory of Computing), 322-329, 1999 | null | null | null | quant-ph | null | Nuclear magnetic resonance offers an appealing prospect for implementation of
quantum computers, because of the long coherence times associated with nuclear
spins, and extensive laboratory experience in manipulating the spins with radio
frequency pulses. Existing proposals, however, suffer from a signal-to-noise
ratio that decays exponentially in the number of qubits in the quantum
computer. This places a severe limit on the size of the computations that can
be performed by such a computer; estimates of that limit are well within the
range in which a conventional computer taking exponentially more steps would
still be practical.
We give an NMR implementation in which the signal-to-noise ratio depends only
on features of NMR technology, not the size of the computer. This provides a
means for NMR computation techniques to scale to sizes at which the exponential
speedup enables quantum computation to solve problems beyond the capabilities
of classical computers.
| [
{
"version": "v1",
"created": "Fri, 24 Apr 1998 21:44:53 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Schulman",
"Leonard J.",
""
],
[
"Vazirani",
"Umesh",
""
]
] |
quant-ph/9804061 | Michael Kleckner | M. Kleckner, A. Ron (Technion - Israel Institute of Technology) | Evanescent Waves are Not Superluminal | 9 pages, 3 figures | null | null | null | quant-ph | null | It is demonstrated that an electromagnetic pulse, which is made to tunnel
trough a barrier, would not be photo-detected before an identical pulse, which
travels the same distance in vacuum.
| [
{
"version": "v1",
"created": "Sun, 26 Apr 1998 10:44:35 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kleckner",
"M.",
"",
"Technion - Israel Institute of Technology"
],
[
"Ron",
"A.",
"",
"Technion - Israel Institute of Technology"
]
] |
quant-ph/9804062 | Bozhidar Zakhariev Iliev | Bozhidar Z. Iliev (Institute for Nuclear Research and Nuclear Energy,
Bulgarian Academy of Sciences, Sofia, Bulgaria) | Fibre bundle formulation of nonrelativistic quantum mechanics. II.
Equations of motion and observables | 19 standard (11pt, A4) LaTeX 2e pages. The packages AMS-LaTeX and
amsfonts are required. New material, references and comments are added. Minor
style chages. Continuation of quan-ph/9803083 and quan-ph/9803084. For
continuation of the series see http://www.inrne.bas.bg/mathmod/bozhome/ | J.Phys.A34:4919-4934,2001 | 10.1088/0305-4470/34/23/309 | null | quant-ph gr-qc hep-th | null | We propose a new systematic fibre bundle formulation of nonrelativistic
quantum mechanics. The new form of the theory is equivalent to the usual one
but it is in harmony with the modern trends in theoretical physics and
potentially admits new generalizations in different directions. In it a pure
state of some quantum system is described by a state section (along paths) of a
(Hilbert) fibre bundle. Its evolution is determined through the bundle
(analogue of the) Schr\"odinger equation. Now the dynamical variables and the
density operator are described via bundle morphisms (along paths). The
mentioned quantities are connected by a number of relations derived in this
work.
In the second part of this investigation we derive several forms of the
bundle (analogue of the) Schr\"odinger equation governing the time evolution of
state sections. We prove that up to a constant the matrix-bundle Hamiltonian,
entering in the bundle analogue of the matrix form of the conventional
Schr\"odinger equation, coincides with the matrix of coefficients of the
evolution transport. This allows to interpret the Hamiltonian as a gauge field.
Here we also apply the bundle approach to the description of observables. It is
shown that to any observable there corresponds a unique Hermitian bundle
morphism (along paths) and vice versa.
| [
{
"version": "v1",
"created": "Sun, 26 Apr 1998 11:56:47 GMT"
},
{
"version": "v2",
"created": "Wed, 21 Oct 1998 16:52:08 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Iliev",
"Bozhidar Z.",
"",
"Institute for Nuclear Research and Nuclear Energy,\n Bulgarian Academy of Sciences, Sofia, Bulgaria"
]
] |
quant-ph/9804063 | Mireille Calvet | B. d'Espagnat | Reply to Aharonov and Anandan's "Meaning of the Density Matrix" | Latex, 13 pages, no figures | null | null | LPTHE Orsay 98-28 | quant-ph | null | Aharonov and Anandan's claim that the notion of ``proper mixture'' is
improper is shown to be unjustified. The point is made that if a purely
operationalist standpoint is taken the three difficulties these authors
describe relatively to the conventional interpretation of density matrices in
fact vanish. It is noted that nevertheless it is very difficult for us to do
without any form of realism, in particular when the quantum measurement problem
is considered, and it is stressed that the proper mixture notion comes in
precisely at this level. The more general question of the real bearing of
Aharonov and Anandan's ideas on the interpretation of quantum mechanics problem
is considered.
| [
{
"version": "v1",
"created": "Mon, 27 Apr 1998 08:54:17 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"d'Espagnat",
"B.",
""
]
] |
quant-ph/9804064 | Hao | Lu-Ming Duan and Guang-Can Guo (University of Science and Technology
of China) | Probabilistic cloning and identification of linearly independent quantum
states | Extension of quant-ph/9705018, 12pages, latex, to appear in Phys.
Rev. Lett | Phys.Rev.Lett. 80 (1998) 4999-5002 | 10.1103/PhysRevLett.80.4999 | null | quant-ph | null | We construct a probabilistic quantum cloning machine by a general
unitary-reduction operation. With a postselection of the measurement results,
the machine yields faithful copies of the input states. It is shown that the
states secretly chosen from a certain set $\$=\left\{\left| \Psi_1\right>
,\left| \Psi_2\right> ,... ,\left| \Psi_n\right> \right\} $ can be
probabilistically cloned if and only if $% \left| \Psi_1\right>$, $\left|
\Psi_2\right>$, $... ,$ and $\left| \Psi_n\right>$ are linearly-independent. We
derive the best possible cloning efficiencies. Probabilistic cloning has close
connection with the problem of identification of a set of states, which is a
type of $n+1$ outcome measurement on $n$ linearly independent states. The
optimal efficiencies for this type of measurement are obtained.
| [
{
"version": "v1",
"created": "Mon, 27 Apr 1998 10:03:09 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Duan",
"Lu-Ming",
"",
"University of Science and Technology\n of China"
],
[
"Guo",
"Guang-Can",
"",
"University of Science and Technology\n of China"
]
] |
quant-ph/9804065 | Stewart E. Barnes | S. E. Barnes | Efficient quantum computing on low temperature spin ensembles | 8 pages no figures | null | null | null | quant-ph | null | A new scheme is proposed which will permit electron spin resonance pulse
techniques to be used to realize a quantum computer with a 100 qbits, or more.
The computation is performed on effective pure states which correspond to
off-diagonal blocks of the density matrix. Described is a scheme which very
efficiently performs the preparation stage and which permits
``pseudo-projective measurement'' to be made on the output. With such
measurements all members of the ensemble remain coherent.
| [
{
"version": "v1",
"created": "Mon, 27 Apr 1998 20:44:22 GMT"
},
{
"version": "v2",
"created": "Sun, 24 May 1998 15:43:00 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Barnes",
"S. E.",
""
]
] |
quant-ph/9804066 | Ashwin Nayak | Ashwin Nayak, Felix Wu | The quantum query complexity of approximating the median and related
statistics | 20 pages. Preliminary draft. Extends results of previous version to
several other problems, and gives some new upper bounds | null | null | null | quant-ph cs.CC | null | Let X = (x_0,...,x_{n-1})$ be a sequence of n numbers. For \epsilon > 0, we
say that x_i is an \epsilon-approximate median if the number of elements
strictly less than x_i, and the number of elements strictly greater than x_i
are each less than (1+\epsilon)n/2. We consider the quantum query complexity of
computing an \epsilon-approximate median, given the sequence X as an oracle. We
prove a lower bound of \Omega(\min{{1/\epsilon},n}) queries for any quantum
algorithm that computes an \epsilon-approximate median with any constant
probability greater than 1/2. We also show how an \epsilon-approximate median
may be computed with O({1/\epsilon}\log({1\/\epsilon}) \log\log({1/\epsilon}))
oracle queries, which represents an improvement over an earlier algorithm due
to Grover. Thus, the lower bound we obtain is essentially optimal. The upper
and the lower bound both hold in the comparison tree model as well.
Our lower bound result is an application of the polynomial paradigm recently
introduced to quantum complexity theory by Beals et al. The main ingredient in
the proof is a polynomial degree lower bound for real multilinear polynomials
that ``approximate'' symmetric partial boolean functions. The degree bound
extends a result of Paturi and also immediately yields lower bounds for the
problems of approximating the kth-smallest element, approximating the mean of a
sequence of numbers, and that of approximately counting the number of ones of a
boolean function. All bounds obtained come within polylogarithmic factors of
the optimal (as we show by presenting algorithms where no such optimal or near
optimal algorithms were known), thus demonstrating the power of the polynomial
method.
| [
{
"version": "v1",
"created": "Wed, 29 Apr 1998 02:00:07 GMT"
},
{
"version": "v2",
"created": "Sun, 15 Nov 1998 01:36:43 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Nayak",
"Ashwin",
""
],
[
"Wu",
"Felix",
""
]
] |
quant-ph/9804067 | Boris F. Samsonov | Vladislav G. Bagrov and Boris F. Samsonov | Supercoherent States of Calogero-Sutherland Oscillator | Talk at the International Workshop on Quantum Systems: New Trends and
Methods 3-7 june 1996. See Proceedings book published by World-Scientific
Singapore 1997, P.15-25 | null | null | null | quant-ph | null | Supersymmetric quantum mechanical model of Calogero-Sutherlend singular
oscillator is constructed. Supercoherent states are defined with the help of
supergroup displacement operator. They are proper states of a fermionic
annihilation operator. Their coordinate and superholomorphic representations
are considered. The supermeasure on superunit disc which realizes the
resolution of the unity is calculated. The cases of exact and spontaneously
broken supersymmetry are treated separately. As an example the supersymmetric
partners of the input Hamiltonian expressed in terms of elementary functions
are given.
| [
{
"version": "v1",
"created": "Wed, 29 Apr 1998 05:28:12 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Bagrov",
"Vladislav G.",
""
],
[
"Samsonov",
"Boris F.",
""
]
] |
quant-ph/9804068 | Kirill Alekseev | Kirill N. Alekseev, Natasha V. Alekseeva, Jan Perina | 1/N-expansion and nonclassical state generation in higher-order
anharmonic oscillators | Paper is withdrawn. See quant-ph/9812019 | null | null | null | quant-ph physics.optics | null | Paper is withdrawn
| [
{
"version": "v1",
"created": "Wed, 29 Apr 1998 08:18:59 GMT"
},
{
"version": "v2",
"created": "Thu, 9 Dec 1999 11:42:31 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Alekseev",
"Kirill N.",
""
],
[
"Alekseeva",
"Natasha V.",
""
],
[
"Perina",
"Jan",
""
]
] |
quant-ph/9804069 | Antoine Suarez | Olivier Costa de Beauregard (Fondation Louis de Broglie, Paris) | Timelike Nonseparability and Retrocausation | 3 pages Latex | null | null | null | quant-ph | null | Renewed interest in the quantum zigzagging causality model is highlighted by
an ingenious proposal by Suarez (quant-ph/9801061) to test the timelike aspect
of nonseparability. Taking advantage of a work by Froehner I argue that the
Dirac representation of a state, has the Bayesian-like connotation of best
estimate given the Hilbert frame chosen. As a measurement perturbs
uncontrollably a system it is (Hoekzema's wording) a retroparation. My bet is
that Suarez' sources and sinks of paired particles operating inside the
coherence length of the laser beam will evidence retrocausation.
| [
{
"version": "v1",
"created": "Wed, 29 Apr 1998 09:37:29 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"de Beauregard",
"Olivier Costa",
"",
"Fondation Louis de Broglie, Paris"
]
] |
quant-ph/9804070 | Wang Zhen | Zhen Wang (Physics Department, LiaoNing Normal University, P. R.
China) | Calculation of Planetary Precession from Quantum-corrected Newton's
Gravitation Law | LaTex, 4 pages | null | null | LNU-98-04 | quant-ph | null | With consideration of quantization of space, we relate Newton's gravitation
with the Second Law of thermodynamics. This leads to a correction to its
original form, which takes into consideration the role of classical
measurement. Our calculation shows this corrected form of gravitation can give
explanation for planetary precession.
| [
{
"version": "v1",
"created": "Wed, 29 Apr 1998 11:14:44 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Wang",
"Zhen",
"",
"Physics Department, LiaoNing Normal University, P. R.\n China"
]
] |
quant-ph/9804071 | Sigmund Kohler | Sigmund Kohler, Ralf Utermann, Peter Hanggi and Thomas Dittrich | Coherent and incoherent chaotic tunneling near singlet-doublet crossings | 23 pages LaTeX, including 22 figures; corrected typos, minor changes | Phys.Rev. E58 (1998) 7219 | 10.1103/PhysRevE.58.7219 | 9376257903 | quant-ph chao-dyn nlin.CD | null | In the spectrum of systems showing chaos-assisted tunneling, three-state
crossings are formed when a chaotic singlet intersects a tunnel doublet. We
study the dissipative quantum dynamics in the vicinity of such crossings. A
harmonically driven double well coupled to a bath serves as a model. Markov and
rotating-wave approximations are introduced with respect to the Floquet
spectrum of the time-dependent central system. The resulting master equation is
integrated numerically. We find various types of transient tunneling,
determined by the relation of the level width to the inherent energy scales of
the crossing. The decay of coherent tunneling can be significantly retarded or
accelerated. Modifications of the quantum asymptotic state by the crossing are
also studied. The comparison with a simple three-state model shows that in
contrast to the undamped case, the participation of states outside the crossing
cannot be neglected in the presence of dissipation.
| [
{
"version": "v1",
"created": "Wed, 29 Apr 1998 16:09:27 GMT"
},
{
"version": "v2",
"created": "Wed, 30 Sep 1998 09:33:18 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Kohler",
"Sigmund",
""
],
[
"Utermann",
"Ralf",
""
],
[
"Hanggi",
"Peter",
""
],
[
"Dittrich",
"Thomas",
""
]
] |
quant-ph/9804072 | Yeranuhy Hakobyan | Ye.M.Hakobyan, G.S.Pogosyan, A.N.Sissakian | On a Generalized D-Dimensional Oscillator: Interbasis Expansions | 12 pages, LaTex | Phys. Atom. Nucl. 61 (1998) 1762-1767; Yad.Fiz. 61 (1998)
1873-1878 | null | null | quant-ph hep-th math-ph math.MP | null | This article deals with nonrelativistic study of a D-dimensional
superintegrable system, which generalizes the ordinary isotropic oscillator
system. The coefficients for the expansion between the hyperspherical and
Cartesian bases (transition matrix), and vice-versa, are found in terms of the
SU(2) Clebsch--Gordan coefficients analytically continued to real values of
their arguments. The diagram method, which allow one to construct a transition
matrix for arbitrary dimension, is developed.
| [
{
"version": "v1",
"created": "Thu, 30 Apr 1998 10:38:27 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Jul 1999 17:16:03 GMT"
},
{
"version": "v3",
"created": "Fri, 9 Jul 1999 19:32:44 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Hakobyan",
"Ye. M.",
""
],
[
"Pogosyan",
"G. S.",
""
],
[
"Sissakian",
"A. N.",
""
]
] |
quant-ph/9804073 | Heinz Rupertsberger | Heinz Rupertsberger | Bohm`s Interpretation of Quantum Mechanics and the Reconstruction of the
Probability Distribution | 7 pages, 1 figure, uses epsfig | null | null | UWThPH-1998-20 | quant-ph | null | Within Bohm`s interpretation of quantum mechanics particles follow classical
trajectories that are determined by the full solution of the time dependent
Schroedinger equation. If this interpretation is consistent it must be possible
to determine the probability distribution at time t from the probability
distribution at time t=0 by using these trajectories. In this paper it is shown
that this is the case indeed.
| [
{
"version": "v1",
"created": "Thu, 30 Apr 1998 12:11:16 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rupertsberger",
"Heinz",
""
]
] |
quant-ph/9804074 | Paolo Bellomo | Paolo Bellomo and C. R. Stroud, Jr | Dispersion of Klauder's temporally stable coherent states for the
hydrogen atom | 6 pages, 2 figures | J.Phys. A31 (1998) L445 | 10.1088/0305-4470/31/24/001 | RTC-04-98 | quant-ph | null | We study the dispersion of the "temporally stable" coherent states for the
hydrogen atom introduced by Klauder. These are states which under temporal
evolution by the hydrogen atom Hamiltonian retain their coherence properties.
We show that in the hydrogen atom such wave packets do not move
quasi-classically; i.e., they do not follow with no or little dispersion the
Keplerian orbits of the classical electron. The poor quantum-classical
correspondence does not improve in the semiclassical limit.
| [
{
"version": "v1",
"created": "Thu, 30 Apr 1998 14:11:27 GMT"
}
] | 2012-08-27T00:00:00 | [
[
"Bellomo",
"Paolo",
""
],
[
"Stroud,",
"C. R.",
"Jr"
]
] |
quant-ph/9804075 | Martin Plenio | Martin B. Plenio and Vlatko Vedral | Entanglement in Quantum Information Theory | Introductory article for Contemporary Physics, 46 pages in preprint
format | Contemp.Phys. 39 (1998) 431-466 | 10.1080/001075198181766 | null | quant-ph | null | Quantum mechanics has many counter-intuitive consequences which contradict
our intuition which is based on classical physics. Here we discuss a special
aspect of quantum mechanics, namely the possibility of entanglement between two
or more particles. We will establish the basic properties of entanglement using
quantum state teleportation. These principles will then allow us to formulate
quantitative measures of entanglement. Finally we will show that the same
general principles can also be used to prove seemingly difficult questions
regarding entanglement dynamics very easily. This will be used to motivate the
hope that we can construct a thermodynamics of entanglement.
| [
{
"version": "v1",
"created": "Thu, 30 Apr 1998 17:38:15 GMT"
},
{
"version": "v2",
"created": "Fri, 22 May 1998 16:35:53 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Plenio",
"Martin B.",
""
],
[
"Vedral",
"Vlatko",
""
]
] |
quant-ph/9804076 | Boris A. Kupershmidt | Boris A. Kupershmidt | Hamiltonian Formalism in Quantum Mechanics | null | J. Nonlinear Math. Phys. 5 (1998), no. 2, 162-180 | 10.2991/jnmp.1998.5.2.8 | JNMP 4/2002 (Article) | quant-ph | null | Heisenberg motion equations in Quantum mechanics can be put into the Hamilton
form. The difference between the commutator and its principal part, the Poisson
bracket, can be accounted for exactly. Canonical transformations in Quantum
mechanics are not, or at least not what they appear to be; their properties are
formulated in a series of Conjectures.
| [
{
"version": "v1",
"created": "Wed, 1 Apr 1998 00:00:00 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Kupershmidt",
"Boris A.",
""
]
] |
quant-ph/9805001 | Serge Massar | N. Linden, S. Massar, S. Popescu | Purifying noisy entanglement requires collective measurements | 5 pages, Latex | Phys.Rev.Lett. 81 (1998) 3279-3282 | 10.1103/PhysRevLett.81.3279 | THU - 98/18 | quant-ph | null | Known entanglement purification protocols for mixed states use collective
measurements on several copies of the state in order to increase the
entanglement of some of them. We address the question of whether it is possible
to purify the entanglement of a state by processing each copy separately. While
this is possible for pure states, we show that this is impossible, in general,
for mixed states. The importance of this result both conceptually and for
experimental realization of purification is discussed. We also give explicit
invariants of an entangled state of two qubits under local actions and
classical communication.
| [
{
"version": "v1",
"created": "Fri, 1 May 1998 12:01:12 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Linden",
"N.",
""
],
[
"Massar",
"S.",
""
],
[
"Popescu",
"S.",
""
]
] |
quant-ph/9805002 | Subhash Kak | Subhash Kak (Louisiana State University) | The Initialization Problem in Quantum Computing | 12 pages (the final version as it was published) | Foundations of Physics, vol 29, 1999, pages 267-279 | null | null | quant-ph | null | The problem of initializing phase in a quantum computing system is
considered. The initialization of phases is a problem when the system is
initially present in an entangled state and also in the application of the
quantum gate transformations since each gate will introduce phase uncertainty.
The accumulation of these random phases will reduce the effectiveness of the
recently proposed quantum computing schemes. The paper also presents general
observations on the nonlocal nature of quantum errors and the expected
performance of the proposed quantum error-correction codes that are based on
the assumption that the errors are either bit-flip or phase-flip or both. It is
argued that these codes cannot directly solve the initialization problem of
quantum computing.
| [
{
"version": "v1",
"created": "Fri, 1 May 1998 15:11:11 GMT"
},
{
"version": "v2",
"created": "Tue, 25 Jun 2002 20:53:30 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kak",
"Subhash",
"",
"Louisiana State University"
]
] |
quant-ph/9805003 | Steven J. van Enk | S.J. van Enk, H.J. Kimble, J.I. Cirac, P. Zoller | Quantum Communication with Phantom Photons | 6 pages RevTex, 4 eps figures included. Revised calculation with more
details about mode structure calculation and the introduction of losses | null | 10.1103/PhysRevA.59.2659 | null | quant-ph | null | We show that quantum information may be transferred between atoms in
different locations by using ``phantom photons'': the atoms are coupled through
electromagnetic fields, but the corresponding field modes do not have to be
fully populated. In the case where atoms are placed inside optical cavities,
errors in quantum information processing due to photon absorption inside the
cavity are diminished in this way. This effect persists up to intercavity
distances of about a meter for the current levels of cavity losses, and may be
useful for distributed quantum computing.
| [
{
"version": "v1",
"created": "Fri, 1 May 1998 17:35:14 GMT"
},
{
"version": "v2",
"created": "Mon, 16 Nov 1998 22:22:53 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"van Enk",
"S. J.",
""
],
[
"Kimble",
"H. J.",
""
],
[
"Cirac",
"J. I.",
""
],
[
"Zoller",
"P.",
""
]
] |
quant-ph/9805004 | Renato Fedele | R. Fedele, V.I. Man'ko | Wigner transform and quantum-like corrections for charged-particle beam
transport | LaTex [sprocl] 3 pages, to be published in Proceedings of the 5th
Wigner Symposium (Vienna, 25-29 August, 1997) | null | null | null | quant-ph | null | It is shown that charged-particle beam transport in the paraxial
approximation can be effectively described with a quantum-like picture in
semiclassical approximation. In particular, the classical Liouville equation
can be suitably replaced by a von Neuman-like equation. Relevant remarks
concerning the standard classical description of the beam transport are given.
| [
{
"version": "v1",
"created": "Fri, 1 May 1998 17:18:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Fedele",
"R.",
""
],
[
"Man'ko",
"V. I.",
""
]
] |
quant-ph/9805005 | Ricardo Moritz Cavalcanti | R. M. Cavalcanti | Wave function of a Brownian particle | 6 pages, REVTEX. Published version | Phys.Rev. E58 (1998) 6807 | 10.1103/PhysRevE.58.6807 | null | quant-ph cond-mat.stat-mech | null | Using the Caldirola-Kanai Hamiltonian, we study the time evolution of the
wave function of a particle whose classical motion is governed by the Langevin
equation. We show, in particular, that if the initial wave function is
Gaussian, then (i) it remains Gaussian for all times, (ii) its width grows,
approaching a finite value when t->infinity, and (iii) its center describes a
Brownian motion, and so the uncertainty in the position of the particle grows
without limit.
| [
{
"version": "v1",
"created": "Sat, 2 May 1998 03:11:06 GMT"
},
{
"version": "v2",
"created": "Fri, 6 Nov 1998 20:46:23 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Cavalcanti",
"R. M.",
""
]
] |
quant-ph/9805006 | Wim van Dam | Wim van Dam (U of Oxford, CWI) | Quantum Oracle Interrogation: Getting all information for almost half
the price | 11 pages LaTeX2e, 1 postscript figure; error analysis added; new
section on approximate interrogation added | Proceedings of the 39th Annual IEEE Symposium on Foundations of
Computer Science (FOCS), pages 362-367 (1998) | 10.1109/SFCS.1998.743486 | CQC-040598 | quant-ph cs.CC | null | Consider a quantum computer in combination with a binary oracle of domain
size N. It is shown how N/2+sqrt(N) calls to the oracle are sufficient to guess
the whole content of the oracle (being an N bit string) with probability
greater than 95%. This contrasts the power of classical computers which would
require N calls to achieve the same task. From this result it follows that any
function with the N bits of the oracle as input can be calculated using
N/2+sqrt(N) queries if we allow a small probability of error. It is also shown
that this error probability can be made arbitrary small by using N/2+O(sqrt(N))
oracle queries.
In the second part of the article `approximate interrogation' is considered.
This is when only a certain fraction of the N oracle bits are requested. Also
for this scenario does the quantum algorithm outperform the classical
protocols. An example is given where a quantum procedure with N/10 queries
returns a string of which 80% of the bits are correct. Any classical protocol
would need 6N/10 queries to establish such a correctness ratio.
| [
{
"version": "v1",
"created": "Mon, 4 May 1998 22:46:43 GMT"
},
{
"version": "v2",
"created": "Wed, 24 Jun 1998 03:29:26 GMT"
},
{
"version": "v3",
"created": "Fri, 11 Sep 1998 18:22:18 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"van Dam",
"Wim",
"",
"U of Oxford, CWI"
]
] |
quant-ph/9805007 | Constantin Brif | C. Brif, A. Mann and M. Revzen (Technion, Haifa) | Classical properties of generalized coherent states: from phase-space
dynamics to Bell's inequality | LaTeX2e, amssymb style, 11 pages, 1 figure. Presented at 2nd Jagna
International Workshop ``Mathematical Methods of Quantum Physics'', January
1998, Jagna, Philippines. To be published in a Festschrift for Professor
Hiroshi Ezawa (Gordon & Breach, London) | null | null | null | quant-ph | null | We review classical properties of harmonic-oscillator coherent states. Then
we discuss which of these classical properties are preserved under the
group-theoretic generalization of coherent states. We prove that the
generalized coherent states of quantum systems with Lie-group symmetries are
the unique Bell states, i.e., the pure quantum states preserving the
fundamental classical property of satisfying Bell's inequality upon splitting.
| [
{
"version": "v1",
"created": "Sat, 2 May 1998 11:41:29 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Brif",
"C.",
"",
"Technion, Haifa"
],
[
"Mann",
"A.",
"",
"Technion, Haifa"
],
[
"Revzen",
"M.",
"",
"Technion, Haifa"
]
] |
quant-ph/9805008 | Dr. BG Sidharth | B.G. Sidharth | A New Approach to Locality and Causality | 12 pages, TeX | null | null | null | quant-ph | null | In the light of some recent results, it is argued that usual concepts of
causality and locality are approximations valid at scales greater than the
Compton wavelength and corresponding time scales. It follows that the "spooky"
non-locality of Quantum Mechanics is not really so and infact is perfectly
consistent with a recently discussed holistic model, which again is
corroborated by latest astrophysical and cosmological observations. This
approach also provides a rationale for the origin of the metric and points to,
what may be called a space time quantization which may be, ultimately,
fundamental.
| [
{
"version": "v1",
"created": "Sun, 3 May 1998 12:43:56 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sidharth",
"B. G.",
""
]
] |
quant-ph/9805009 | Rabin Banerji | R.Banerjee and S.Ghosh | The Chiral Oscillator and its Applications in Quantum Theory | Latex | J.Phys. A31 (1998) L603-L608 | 10.1088/0305-4470/31/36/002 | null | quant-ph | null | The fundamental importance of the chiral oscillator is elaborated. Its
quantum invariants are computed. As an application the Zeeman effect is
analysed. We also show that the chiral oscillator is the most basic example of
a duality invariant model, simulating the effect of the familiar
electric-magnetic duality.
| [
{
"version": "v1",
"created": "Mon, 4 May 1998 10:33:10 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Banerjee",
"R.",
""
],
[
"Ghosh",
"S.",
""
]
] |
quant-ph/9805010 | Miguel Navarro | Miguel Navarro | Toward a finite-dimensional formulation of Quantum Field Theory | Latex file, 12 pages | Found.Phys.Lett. 11 (1998) 585-593 | null | null | quant-ph | null | Rules of quantization and equations of motion for a finite-dimensional
formulation of Quantum Field Theory are proposed which fulfill the following
properties: a) both the rules of quantization and the equations of motion are
covariant; b) the equations of evolution are second order in derivatives and
first order in derivatives of the space-time co-ordinates; and c) these rules
of quantization and equations of motion lead to the usual (canonical) rules of
quantization and the (Schr\"odinger) equation of motion of Quantum Mechanics in
the particular case of mechanical systems. We also comment briefly on further
steps to fully develop a satisfactory quantum field theory and the difficuties
which may be encountered when doing so.
| [
{
"version": "v1",
"created": "Mon, 4 May 1998 15:07:24 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Navarro",
"Miguel",
""
]
] |
quant-ph/9805011 | Arkadiusz Jadczyk | Ph. Blanchard, A. Jadczyk, R. Olkiewicz | The Piecewise Deterministic Process Associated to EEQT | 22 pages Latex, revtex. Replacement contains a more detailed
discussion of the inhomogeneous Markov process and several additional
explanations | null | null | null | quant-ph | null | In the framework of Event Enhanced Quantum Theory (EEQT) a probabilistic
construction of the piecewise deterministic process associated with a dynamical
semigroup is presented. The process generates sample histories of individual
systems quantums systems continuously coupled to classical measuring devices;
it gives a unique algorithm generating time series of pointer readings in real
experiments with quantum systems.
| [
{
"version": "v1",
"created": "Mon, 4 May 1998 15:26:57 GMT"
},
{
"version": "v2",
"created": "Tue, 28 Sep 1999 13:08:28 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Blanchard",
"Ph.",
""
],
[
"Jadczyk",
"A.",
""
],
[
"Olkiewicz",
"R.",
""
]
] |
quant-ph/9805012 | Tabish Qureshi | N.D. Hari Dass (IMSc, Madras, India) and Tabish Qureshi (IGCAR,
Kalpakkam, India.) | Critique of Protective Measurements | 14 pages RevTex, published version with change in title | Phys.Rev.A59:2590,1999 | 10.1103/PhysRevA.59.2590 | IMSc/98/05/21 | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently proposed idea of "protective" measurement of a quantum state is
critically examined, and generalized. Earlier criticisms of the idea are
discussed and their relevance to the proposal assessed. Several constraints on
measuring apparatus required by "protective" measurements are discussed, with
emphasis on how they may restrict their experimental feasibility. Though
"protective" measurements result in an unchanged system state and a shift of
the pointer proportional to the expectation value of the measured observable in
the system state, the actual reading of the pointer position gives rise to
several subtleties. We propose several schemes for reading pointer position,
both when the apparatus is treated as a classical system as well as when its
quantum aspects are taken into account, that address these issues. The tiny
entanglement which is always present due to deviation from extreme adiabaticity
in realistic situations is argued to be the weakest aspect of the proposal.
Because of this, one can never perform a protective measurement on a single
quantum system with absolute certainty. This clearly precludes an ontological
status for the wave function. Several other conceptual issues are also
discussed.
| [
{
"version": "v1",
"created": "Mon, 4 May 1998 20:23:00 GMT"
},
{
"version": "v2",
"created": "Mon, 11 May 1998 04:55:04 GMT"
},
{
"version": "v3",
"created": "Mon, 2 Nov 1998 16:02:50 GMT"
},
{
"version": "v4",
"created": "Wed, 4 Nov 1998 05:45:51 GMT"
},
{
"version": "v5",
"created": "Tue, 23 Aug 2011 11:15:56 GMT"
}
] | 2011-08-24T00:00:00 | [
[
"Dass",
"N. D. Hari",
"",
"IMSc, Madras, India"
],
[
"Qureshi",
"Tabish",
"",
"IGCAR,\n Kalpakkam, India."
]
] |
quant-ph/9805013 | Dr. BG Sidharth | B.G. Sidharth | Towards a Unified Description of the Fundamental Interactions | 8 pages, TeX | Chaotic Universe,Nova Science,New York,2001 | null | null | quant-ph | null | We consider a recent successful model of leptons as Kerr-Newman type Black
Holes in a Quantum Mechanical context. The model leads to a cosmology which
predicts an ever expanding accelerating universe with decreasing density and to
the conclusion that at Compton wavelength scales, electrons would exhibit low
dimensionality, both of which conclusions have been verified by several
independent experiments and observations very recently. In this preliminary
communication we indicate how the above model describes the quarks' fractional
charges, handedness and masses (as any fundamental theory should) and could
lead to a unified description of the four fundamental interactions.
| [
{
"version": "v1",
"created": "Wed, 6 May 1998 00:49:41 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sidharth",
"B. G.",
""
]
] |
quant-ph/9805014 | Sergei Shabanov | Sergei V. Shabanov and John R. Klauder | Path Integral Quantization and Riemannian-Symplectic Manifolds | plain Latex, 9 pages, no figures | Phys.Lett. B435 (1998) 343-349 | 10.1016/S0370-2693(98)00798-9 | null | quant-ph hep-th math-ph math.MP | null | We develop a mathematically well-defined path integral formalism for general
symplectic manifolds. We argue that in order to make a path integral
quantization covariant under general coordinate transformations on the phase
space and involve a genuine functional measure that is both finite and
countably additive, the phase space manifold should be equipped with a
Riemannian structure (metric). A suitable method to calculate the metric is
also proposed.
| [
{
"version": "v1",
"created": "Wed, 6 May 1998 15:22:52 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Shabanov",
"Sergei V.",
""
],
[
"Klauder",
"John R.",
""
]
] |
quant-ph/9805015 | Robert R. Tucci | Robert R. Tucci | A Rudimentary Quantum Compiler | 1 LaTeX file (25 pages), 9 eps files | null | null | null | quant-ph | null | We present a new algorithm for reducing an arbitrary unitary matrix into a
sequence of elementary operations (operations such as controlled-nots and qubit
rotations). Such a sequence of operations can be used to manipulate an array of
quantum bits (i.e., a quantum computer). We report on a C++ program called
"Qubiter" that implements our algorithm. Qubiter source code is publicly
available.
| [
{
"version": "v1",
"created": "Thu, 7 May 1998 05:06:38 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Tucci",
"Robert R.",
""
]
] |
quant-ph/9805016 | Robert R. Tucci | Robert R. Tucci | How to Compile A Quantum Bayesian Net | 1 LaTeX file (14 pages), 5 eps files | null | null | null | quant-ph | null | We show how to express the information contained in a Quantum Bayesian (QB)
net as a product of unitary matrices. If each of these unitary matrices is
expressed as a sequence of elementary operations (operations such as
controlled-nots and qubit rotations), then the result is a sequence of
operations that can be used to run a quantum computer. QB nets have been run
entirely on a classical computer, but one expects them to run faster on a
quantum computer.
| [
{
"version": "v1",
"created": "Thu, 7 May 1998 05:33:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Tucci",
"Robert R.",
""
]
] |
quant-ph/9805017 | Richard Jozsa | Richard Jozsa, Michal Horodecki, Pawel Horodecki and Ryszard Horodecki | Universal Quantum Information Compression | RevTex 4 pages | Phys.Rev.Lett. 81 (1998) 1714-1717 | 10.1103/PhysRevLett.81.1714 | null | quant-ph | null | Suppose that a quantum source is known to have von Neumann entropy less than
or equal to S but is otherwise completely unspecified. We describe a method of
universal quantum data compression which will faithfully compress the quantum
information of any such source to S qubits per signal (in the limit of large
block lengths).
| [
{
"version": "v1",
"created": "Thu, 7 May 1998 07:59:07 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Jozsa",
"Richard",
""
],
[
"Horodecki",
"Michal",
""
],
[
"Horodecki",
"Pawel",
""
],
[
"Horodecki",
"Ryszard",
""
]
] |
quant-ph/9805018 | Marc-Thierry Jaekel | Philippe Matherat (Ecole Nationale Supe'rieure des
Te'le'communications) and Marc-Thierry Jaekel (Laboratoire de Physique
The'orique de l'Ecole Normale Supe'rieure) | Logical Dissipation of Automata Implements - Dissipation of Computation | 12 pages, 13 figures | T.S.I. 15 (1996) 1079 | null | LPTENS 98/17A | quant-ph math.LO | null | As revealed by discussions of principle on energy dissipation by computers,
logic imposes constraints on physical systems designed for a logical function.
We define a notion of logical dissipation for a finite automaton. We discuss
the constraints associated with physical implementation of automata and exhibit
the role played by modularity for testability. As a result, practical
computers, which are necessarily modular, dissipate proportionally to
computation time.
| [
{
"version": "v1",
"created": "Thu, 7 May 1998 08:11:32 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Matherat",
"Philippe",
"",
"Ecole Nationale Supe'rieure des\n Te'le'communications"
],
[
"Jaekel",
"Marc-Thierry",
"",
"Laboratoire de Physique\n The'orique de l'Ecole Normale Supe'rieure"
]
] |
quant-ph/9805019 | Dagmar Bruss | Dagmar Bruss | Optimal eavesdropping in quantum cryptography with six states | 4 pages, 1 figure | Phys.Rev.Lett. 81 (1998) 3018-3021 | 10.1103/PhysRevLett.81.3018 | null | quant-ph | null | A generalization of the quantum cryptographic protocol by Bennett and
Brassard is discussed, using three conjugate bases, i.e. six states. By
calculating the optimal mutual information between sender and eavesdropper it
is shown that this scheme is safer against eavesdropping on single qubits than
the one based on two conjugate bases. We also address the question for a
connection between the maximal classical correlation in a generalized Bell
inequality and the intersection of mutual informations between sender/receiver
and sender/eavesdropper.
| [
{
"version": "v1",
"created": "Thu, 7 May 1998 09:35:45 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Oct 1998 09:13:29 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Bruss",
"Dagmar",
""
]
] |
quant-ph/9805020 | Vladimir Buzek | V. Buzek, G. Drobny, R. Derka, G. Adam, H. Wiedemann | Quantum State Reconstruction From Incomplete Data | 85 pages, revtex, 15 figures, 9 tables | null | null | null | quant-ph | null | Knowing and guessing, these are two essential epistemological pillars in the
theory of quantum-mechanical measurement. As formulated quantum mechanics is a
statistical theory. In general, a priori unknown states can be completely
determined only when measurements on infinite ensembles of identically prepared
quantum systems are performed. But how one can estimate (guess) quantum state
when just incomplete data are available (known)? What is the most reliable
estimation based on a given measured data? What is the optimal measurement
providing only a finite number of identically prepared quantum objects are
available? These are some of the questions we address. We present several
schemes for a reconstruction of states of quantum systems from measured data:
(1) We show how the maximum entropy (MaxEnt) principle can be efficiently used
for an estimation of quantum states on incomplete observation levels. (2) We
show how Bayesian inference can be used for reconstruction of quantum states
when only a finite number of identically prepared systems are measured. (3) We
describe the optimal generalized measurement of a finite number of identically
prepared quantum systems which results in the estimation of a quantum state
with the highest fidelity.
| [
{
"version": "v1",
"created": "Thu, 7 May 1998 13:17:37 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Buzek",
"V.",
""
],
[
"Drobny",
"G.",
""
],
[
"Derka",
"R.",
""
],
[
"Adam",
"G.",
""
],
[
"Wiedemann",
"H.",
""
]
] |
quant-ph/9805021 | Antoine Suarez | Antoine Suarez (Center for Quantum Philosophy, Zurich) | Quantum mechanical 'Backward in Time'? Comments, Answers, and the Causal
Indistinguishability Condition | 16 pages Latex, 1 eps figure. The same content differently arranged
has been submitted to Physics Letters A | null | null | null | quant-ph | null | We discuss a number of comments on quant-ph/9801061, and propose to introduce
the concept of 'Causal Indistinguishability'. The incompatibility between
Quantum Mechanics and Nonlocal Causality appears to be unavoidable: upholding
of Quantum Mechanics by experiment would mean to live with influences backward
in time, just as we are now living with such faster than light.
| [
{
"version": "v1",
"created": "Thu, 7 May 1998 19:02:34 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Suarez",
"Antoine",
"",
"Center for Quantum Philosophy, Zurich"
]
] |
quant-ph/9805022 | Jon Machta | J. Machta | Phase Information in Quantum Oracle Computing | 3 pages, latex | null | null | null | quant-ph | null | Computational devices may be supplied with external sources of information
(oracles). Quantum oracles may transmit phase information which is available to
a quantum computer but not a classical computer. One consequence of this
observation is that there is an oracle which is of no assistance to a classical
computer but which allows a quantum computer to solve undecidable problems.
Thus useful relativized separations between quantum and classical complexity
classes must exclude the transmission of phase information from oracle to
computer.
| [
{
"version": "v1",
"created": "Thu, 7 May 1998 20:50:15 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Machta",
"J.",
""
]
] |
quant-ph/9805023 | Stefano Liberati | Matt Visser, S. Liberati, F. Belgiorno, D.W. Sciama | Sonoluminescence: Bogolubov coefficients for the QED vacuum of a
time-dependent dielectric bubble | 4 pages, RevTeX, 2 figures (.eps file) included with graphics.sty.
Major revisions: physical scenario clarified, additional numerical estimates | Phys.Rev.Lett. 83 (1999) 678-681 | 10.1103/PhysRevLett.83.678 | null | quant-ph cond-mat hep-ph hep-th | null | We extend Schwinger's ideas regarding sonoluminescence by explicitly
calculating the Bogolubov coefficients relating the QED vacuum states
associated with changes in a dielectric bubble. Sudden (non-adiabatic) changes
in the refractive index lead to an efficient production of real photons with a
broadband spectrum, and a high-frequency cutoff that arises from the asymptotic
behaviour of the dielectric constant.
| [
{
"version": "v1",
"created": "Fri, 8 May 1998 17:40:55 GMT"
},
{
"version": "v2",
"created": "Fri, 14 May 1999 20:21:59 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Visser",
"Matt",
""
],
[
"Liberati",
"S.",
""
],
[
"Belgiorno",
"F.",
""
],
[
"Sciama",
"D. W.",
""
]
] |
quant-ph/9805024 | Nicolas Cerf | Nicolas J. Cerf (Caltech) | Asymmetric quantum cloning machines in any dimension | 18 pages RevTeX, 3 Postscript figures; new discussion on no-cloning
uncertainty relations, several corrections, added references | J.Mod.Opt. 47 (2000) 187 | 10.1080/09500340008244036 | KRL MAP-224 | quant-ph | null | A family of asymmetric cloning machines for $N$-dimensional quantum states is
introduced. These machines produce two imperfect copies of a single state that
emerge from two distinct Heisenberg channels. The tradeoff between the quality
of these copies is shown to result from a complementarity akin to Heisenberg
uncertainty principle. A no-cloning inequality is derived for isotropic
cloners: if $\pi_a$ and $\pi_b$ are the depolarizing fractions associated with
the two copies, the domain in $(\sqrt{\pi_a},\sqrt{\pi_b})$-space located
inside a particular ellipse representing close-to-perfect cloning is forbidden.
More generally, a no-cloning uncertainty relation is discussed, quantifying the
impossibility of copying imposed by quantum mechanics. Finally, an asymmetric
Pauli cloning machine is defined that makes two approximate copies of a quantum
bit, while the input-to-output operation underlying each copy is a (distinct)
Pauli channel. The class of symmetric Pauli cloning machines is shown to
provide an upper bound on the quantum capacity of the Pauli channel of
probabilities $p_x$, $p_y$ and $p_z$.
| [
{
"version": "v1",
"created": "Fri, 8 May 1998 23:41:37 GMT"
},
{
"version": "v2",
"created": "Mon, 31 Aug 1998 23:15:30 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Cerf",
"Nicolas J.",
"",
"Caltech"
]
] |
quant-ph/9805025 | Michael Mueller | Michael Mueller | Product rule for gauge invariant Weyl symbols and its application to the
semiclassical description of guiding center motion | 24 pages, RevTeX, no figures; shortened version will be published in
J.Phys.A | J.Phys.A32:1035-1052,1999 | 10.1088/0305-4470/32/6/014 | null | quant-ph | null | We derive a product rule for gauge invariant Weyl symbols which provides a
generalization of the well-known Moyal formula to the case of non-vanishing
electromagnetic fields. Applying our result to the guiding center problem we
expand the guiding center Hamiltonian into an asymptotic power series with
respect to both Planck's constant $\hbar$ and an adiabaticity parameter already
present in the classical theory. This expansion is used to determine the
influence of quantum mechanical effects on guiding center motion.
| [
{
"version": "v1",
"created": "Sat, 9 May 1998 00:38:26 GMT"
},
{
"version": "v2",
"created": "Fri, 20 Nov 1998 12:49:15 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Mueller",
"Michael",
""
]
] |
quant-ph/9805026 | Ricardo Moritz Cavalcanti | R. M. Cavalcanti and C. A. A. de Carvalho | Bound states of a spin-1/2 charged particle in a magnetic flux tube | 4 pages, REVTEX. Final version, to appear in J. Phys. A: Math. Gen | J.Phys.A31:7061-7063,1998 | 10.1088/0305-4470/31/34/009 | null | quant-ph cond-mat math-ph math.MP | null | We study a spin-1/2 charged particle with gyromagnetic factor g>2 moving in a
plane threaded by a magnetic flux tube. We prove that, if the magnetic field
(i) has radial symmetry, (ii) has compact support and (iii) does not change
sign, there is at least one bound state for each angular momentum l in the
interval [0,v], where v (assumed positive) is the total magnetic flux in units
of the quantum of flux.
| [
{
"version": "v1",
"created": "Sat, 9 May 1998 00:55:15 GMT"
},
{
"version": "v2",
"created": "Wed, 8 Jul 1998 05:17:33 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Cavalcanti",
"R. M.",
""
],
[
"de Carvalho",
"C. A. A.",
""
]
] |
quant-ph/9805027 | Todd Brun | Tarso B.L. Kist, M. Orszag, T.A. Brun, L. Davidovich | Physical interpretation of stochastic Schroedinger equations in cavity
QED | 12 pages RevTeX 3.0 + 6 figures (GIF format; for higher-resolution
postscript images or hardcopies contact the authors.) Submitted to Phys. Rev.
A | J. Optics B 1, 251-263 (1999) | 10.1088/1464-4266/1/2/009 | NSF-ITP-98-056 | quant-ph | null | We propose physical interpretations for stochastic methods which have been
developed recently to describe the evolution of a quantum system interacting
with a reservoir. As opposed to the usual reduced density operator approach,
which refers to ensemble averages, these methods deal with the dynamics of
single realizations, and involve the solution of stochastic Schr\"odinger
equations. These procedures have been shown to be completely equivalent to the
master equation approach when ensemble averages are taken over many
realizations. We show that these techniques are not only convenient
mathematical tools for dissipative systems, but may actually correspond to
concrete physical processes, for any temperature of the reservoir. We consider
a mode of the electromagnetic field in a cavity interacting with a beam of two-
or three-level atoms, the field mode playing the role of a small system and the
atomic beam standing for a reservoir at finite temperature, the interaction
between them being given by the Jaynes-Cummings model. We show that the
evolution of the field states, under continuous monitoring of the state of the
atoms which leave the cavity, can be described in terms of either the Monte
Carlo Wave-Function (quantum jump) method or a stochastic Schr\"odinger
equation, depending on the system configuration. We also show that the Monte
Carlo Wave-Function approach leads, for finite temperatures, to localization
into jumping Fock states, while the diffusion equation method leads to
localization into states with a diffusing average photon number, which for
sufficiently small temperatures are close approximations to mildly squeezed
states.
| [
{
"version": "v1",
"created": "Mon, 11 May 1998 21:40:18 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Kist",
"Tarso B. L.",
""
],
[
"Orszag",
"M.",
""
],
[
"Brun",
"T. A.",
""
],
[
"Davidovich",
"L.",
""
]
] |
quant-ph/9805028 | David Marcus Appleby | D. M. Appleby | Retrodictively Optimal Localisations in Phase Space | 11 pages, 2 figures. AMS Latex. Replaced with published version | J.Mod.Opt. 46(1999) 813-823 | 10.1080/09500349908231306 | QMW-PH-98-21 | quant-ph | null | In a previous paper it was shown that the distribution of measured values for
a retrodictively optimal simultaneous measurement of position and momentum is
always given by the initial state Husimi function. This result is now
generalised to retrodictively optimal simultaneous measurements of an arbitrary
pair of rotated quadratures x_theta1 and x_theta2. It is shown, that given any
such measurement, it is possible to find another such measurement,
informationally equivalent to the first, for which the axes defined by the two
quadratures are perpendicular. It is further shown that the distribution of
measured values for such a meaurement belongs to the class of generalised
Husimi functions most recently discussed by Wuensche and Buzek. The class
consists of the subset of Wodkiewicz's operational probability distributions
for which the filter reference state is a squeezed vaccuum state.
| [
{
"version": "v1",
"created": "Sun, 10 May 1998 19:00:50 GMT"
},
{
"version": "v2",
"created": "Mon, 22 Nov 1999 23:32:37 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Appleby",
"D. M.",
""
]
] |
quant-ph/9805029 | Juan J. G. Ripoll | Juan J. G. Ripoll, Victor M. Perez-Garcia | Strong excitations of a Bose--Einstein condensate: Barrier resonances | 4 pages, 3 EPS figures | null | null | null | quant-ph | null | We study the dynamics of a forced condensed atom cloud and relate the
behavior to a classical Mathieu oscillator in a singular potential. It is found
that there are wide resonances which can strongly affect the dynamics even when
dissipation is present. The behavior is characteristic of condensed clouds of
any shape and has experimental relevance.
| [
{
"version": "v1",
"created": "Sun, 10 May 1998 18:32:00 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ripoll",
"Juan J. G.",
""
],
[
"Perez-Garcia",
"Victor M.",
""
]
] |
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