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quant-ph/9802064 | Vladimir Skarzhinsky | Juergen Audretsch and Vladimir Skarzhinsky | Aharonov-Bohm scattering of neutral atoms with induced electric dipole
moments | 9 pages, LaTeX, 2 figures | Phys.Lett. A241 (1998) 7-13 | 10.1016/S0375-9601(98)00118-2 | Preprint KONS-RGKU-98-01 | quant-ph | null | We investigate the scattering of neutral polarizable atoms from an
electrically charged wire placed in a homogeneous magnetic field. The atoms
carry an induced electric dipole. The reflecting wire is discussed. We
calculate the scattering amplitude and cross section the practically more
important case that atoms are totally absorbed at the surface of the wire. If
the magnetic field is present, there is a dominating Aharonov-Bohm peak in the
forward direction followed by decreasing oscillations for larger angles. An
experimental realization of this modulated Aharonov-Bohm scattering should be
possible.
| [
{
"version": "v1",
"created": "Wed, 25 Feb 1998 13:10:21 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Audretsch",
"Juergen",
""
],
[
"Skarzhinsky",
"Vladimir",
""
]
] |
quant-ph/9802065 | Martin Plenio | Vlatko Vedral and Martin B. Plenio | Basics of Quantum Computation | 28 pages including 17 figures, invited basic review article for
Progress in Quantum Electronics | Prog.Quant.Electron.22:1,1998 | 10.1016/S0079-6727(98)00004-4 | null | quant-ph | null | Quantum computers require quantum logic, something fundamentally different to
classical Boolean logic. This difference leads to a greater efficiency of
quantum computation over its classical counter-part. In this review we explain
the basic principles of quantum computation, including the construction of
basic gates, and networks. We illustrate the power of quantum algorithms using
the simple problem of Deutsch, and explain, again in very simple terms, the
well known algorithm of Shor for factorisation of large numbers into primes. We
then describe physical implementations of quantum computers, focusing on one in
particular, the linear ion-trap realization. We explain that the main obstacle
to building an actual quantum computer is the problem of decoherence, which we
show may be circumvented using the methods of quantum error correction.
| [
{
"version": "v1",
"created": "Wed, 25 Feb 1998 17:47:18 GMT"
}
] | 2011-08-04T00:00:00 | [
[
"Vedral",
"Vlatko",
""
],
[
"Plenio",
"Martin B.",
""
]
] |
quant-ph/9802066 | Christiane Quesne | C. Quesne, N. Vansteenkiste | $C_{\lambda}$-extended harmonic oscillator and (para)supersymmetric
quantum mechanics | 18 pages, LaTeX 2e | Phys.Lett. A240 (1998) 21-28 | 10.1016/S0375-9601(98)00046-2 | ULB/229/CQ/97/5 | quant-ph math-ph math.MP math.QA | null | $C_{\lambda}$-extended oscillator algebras are realized as generalized
deformed oscillator algebras. For $\lambda = 3$, the spectrum of the
corresponding bosonic oscillator Hamiltonian is shown to strongly depend on the
algebra parameters. A connection with cyclic shape invariant potentials is
noted. A bosonization of PSSQM of order two is obtained.
| [
{
"version": "v1",
"created": "Thu, 26 Feb 1998 14:03:18 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Quesne",
"C.",
""
],
[
"Vansteenkiste",
"N.",
""
]
] |
quant-ph/9802067 | Paul Benioff | Paul Benioff(Argonne National Laboratory) | Quantum Robots and Environments | 30 Latex pages, 3 Postscript figures, Minor mathematical corrections,
accepted for publication, Phys Rev A | Phys.Rev.A58:893,1998 | 10.1103/PhysRevA.58.893 | null | quant-ph | null | Quantum robots and their interactions with environments of quantum systems
are described and their study justified. A quantum robot is a mobile quantum
system that includes a quantum computer and needed ancillary systems on board.
Quantum robots carry out tasks whose goals include specified changes in the
state of the environment or carrying out measurements on the environment. Each
task is a sequence of alternating computation and action phases. Computation
phase activities include determination of the action to be carried out in the
next phase and possible recording of information on neighborhood environmental
system states. Action phase activities include motion of the quantum robot and
changes of neighborhood environment system states. Models of quantum robots and
their interactions with environments are described using discrete space and
time. To each task is associated a unitary step operator T that gives the
single time step dynamics. T = T_{a}+T_{c} is a sum of action phase and
computation phase step operators. Conditions that T_{a} and T_{c} should
satisfy are given along with a description of the evolution as a sum over paths
of completed phase input and output states. A simple example of a task carrying
out a measurement on a very simple environment is analyzed. A decision tree for
the task is presented and discussed in terms of sums over phase paths. One sees
that no definite times or durations are associated with the phase steps in the
tree and that the tree describes the successive phase steps in each path in the
sum.
| [
{
"version": "v1",
"created": "Thu, 26 Feb 1998 19:44:43 GMT"
},
{
"version": "v2",
"created": "Tue, 28 Apr 1998 21:07:30 GMT"
}
] | 2008-12-30T00:00:00 | [
[
"Benioff",
"Paul",
"",
"Argonne National Laboratory"
]
] |
quant-ph/9802068 | null | J. G. Muga and R. F. Snider | Solvable three boson model with attractive delta function interactions | Revtex, 17 pages, 9 ps figures, to appear in Phys. Rev. A | null | 10.1103/PhysRevA.57.3317 | ULL-FIS-980201 | quant-ph | null | A one parameter solvable model for three bosons subject to delta function
interactions in one-dimension with periodic boundary conditions is studied. The
energy levels and wave functions are classified and given explicitly in terms
of three momenta. In particular, eigenstates and eigenvalues are described as
functions of the model parameter, c. Some of the states are given in terms of
complex momenta and represent dimer or trimer configurations for large negative
c. The asymptotic behaviour for small and large values of the parameter, and at
thresholds between real and complex momenta is provided. The properties of the
potential energy are also discussed.
| [
{
"version": "v1",
"created": "Thu, 26 Feb 1998 20:16:58 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Muga",
"J. G.",
""
],
[
"Snider",
"R. F.",
""
]
] |
quant-ph/9802069 | Allan Widom | V. Kidambi and A. Widom | Causality and Electromagnetic Transmissions Through Materials | Plain TeX, No figures, 5 pages | Phys.Lett. A253 (1999) 125-131 | 10.1016/S0375-9601(99)00076-6 | MQC 0100 | quant-ph | null | There have been several experiments which hint at evidence for superluminal
transport of electromagnetic energy through a material slab. On the theoretical
side, it has appeared evident that acausal signals are indeed possible in
quantum electrodynamics. However, it is unlikely that superluminal signals can
be understood on the basis of a purely classical electrodynamic signals passing
through a material. The classical and quantum theories represent quite
different views, and it is the quantum view which may lead to violations of
Einstein causality.
| [
{
"version": "v1",
"created": "Fri, 27 Feb 1998 23:29:05 GMT"
},
{
"version": "v2",
"created": "Mon, 2 Mar 1998 15:50:38 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Kidambi",
"V.",
""
],
[
"Widom",
"A.",
""
]
] |
quant-ph/9802070 | Eric Rains | Eric M. Rains (AT&T Research) | Monotonicity of the quantum linear programming bound | 5 pages, AMSTeX | null | null | null | quant-ph | null | The most powerful technique known at present for bounding the size of quantum
codes of prescribed minimum distance is the quantum linear programming bound.
Unlike the classical linear programming bound, it is not immediately obvious
that if the quantum linear programming constraints are satisfiable for
dimension K, that the constraints can be satisfied for all lower dimensions. We
show that the quantum linear programming bound is indeed monotonic in this
sense, and give an explicitly monotonic reformulation.
| [
{
"version": "v1",
"created": "Fri, 27 Feb 1998 18:51:14 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rains",
"Eric M.",
"",
"AT&T Research"
]
] |
quant-ph/9802071 | null | Vladimir S. Mashkevich (Institute of Physics, Kiev) | On Quantum Nonlocality: Using Prediction of a Distant Measurement
Outcome | 5 pages, LATEX 2.09 | null | null | IP 4/98 | quant-ph | null | We assume that an event caused by a correlation between outcomes of two
causally separated measurements is, by definition, a manifestation of quantum
nonlocality, or superluminal influence. An example of the Alice-Bob type is
given, with the characters replaced. The relationship between quantum
nonlocality and relativity theory is touched upon.
| [
{
"version": "v1",
"created": "Fri, 27 Feb 1998 22:29:34 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Mashkevich",
"Vladimir S.",
"",
"Institute of Physics, Kiev"
]
] |
quant-ph/9803001 | null | Guang-jiong Ni (Depratment of Physics, Fudan University, Shanghai,
P.R. China) | Einstein-Pauli-Yukawa Paradox --- What is the Physical Reality? | 10 pages, Latex, no figure | null | null | null | quant-ph | null | What is the momentum spectrum of a particle moving in an infinite deep square
well? Einstein, Pauli and Yukawa had adopted different point of view than that
in usual text books. The theoretical and experimental implication of this
problem is discussed.
| [
{
"version": "v1",
"created": "Sat, 28 Feb 1998 02:23:02 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ni",
"Guang-jiong",
"",
"Depratment of Physics, Fudan University, Shanghai,\n P.R. China"
]
] |
quant-ph/9803002 | Arkadiusz Jadczyk | G.G. Emch and A Jadczyk | On Quaternions and Monopoles | 12 pages amstex, Postscript file available also at
http://www.ift.uni.wroc.pl/~ajad | Canadian Mathematical Society Proceedings 20, 157-164 (2000) | null | null | quant-ph | null | It is shown that the quaternionic Hilbert space formulation of quantum
mechanics allows a quantization, based on a generalized system of
imprimitivity, that leads to a description of the motion of a quantum particle
in the field of a magnetic monopole. The corresponding Hamilton operator is
linked to the theory of projective representations in the weakened form
proposed by Adler.
| [
{
"version": "v1",
"created": "Sat, 28 Feb 1998 17:35:45 GMT"
}
] | 2022-04-05T00:00:00 | [
[
"Emch",
"G. G.",
""
],
[
"Jadczyk",
"A",
""
]
] |
quant-ph/9803003 | Bhabani Prasad Mandal | Avinash Khare and Bhabani Prasad Mandal | A Number of Quasi-Exactly Solvable N-body Problems | 17pages, Revtex, no figure | J.Math.Phys. 39 (1998) 5789-5794 | 10.1063/1.532593 | SINP/TNP-98-07 | quant-ph cond-mat hep-th math-ph math.MP | null | We present several examples of quasi-exactly solvable $N$-body problems in
one, two and higher dimensions. We study various aspects of these problems in
some detail. In particular, we show that in some of these examples the
corresponding polynomials form an orthogonal set and many of their properties
are similar to those of the Bender-Dunne polynomials. We also discuss QES
problems where the polynomials do not form an orthogonal set.
| [
{
"version": "v1",
"created": "Mon, 2 Mar 1998 09:08:28 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Khare",
"Avinash",
""
],
[
"Mandal",
"Bhabani Prasad",
""
]
] |
quant-ph/9803004 | null | A. Angelow (Institute of Solid State Physics, Sofia, Bulgaria) | Frequency Switching of Quantum Harmonic Oscillator with Time-Dependent
Frequency | 13 pages, including 5 figures, 21 bibliographic references | null | null | null | quant-ph | null | An explicit solution of the equation for the classical harmonic oscillator
with smooth switching of the frequency has been found . A detailed analysis of
a quantum harmonic oscillator with such frequency has been done on the base of
the method of linear invariants. It has been shown that such oscillator
possesses cofluctuant states, different from widely studied Glauber's coherent
and "ideal" squeezed states.
| [
{
"version": "v1",
"created": "Mon, 2 Mar 1998 14:44:45 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Mar 1998 14:57:32 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Angelow",
"A.",
"",
"Institute of Solid State Physics, Sofia, Bulgaria"
]
] |
quant-ph/9803005 | Dr N. Mavromatos | N.E. Mavromatos, D.V. Nanopoulos, I. Samaras and K. Zioutas | Ferroelectrics and their possible involvement in Biology | 7 pages latex, one figure, included separately as ps file. Based on
talks by N.E.M. and K.Z. at the Workshop `Biophysics of the Cytoskeleton',
Banff, Canada, August 18-22 1997. To appear in Adv. Str. Biol | null | null | ACT-2/98, CTP-TAMU-8/98, OUTP-98-19P | quant-ph cond-mat | null | We present the main properties of ferroelectricity, with emphasis given to a
specific family of hydrated ferroelectric crystals, which can serve as model
systems for corresponding configurations in biology like the microtubules. An
experimental method is described, which allows to establish the ferroelectric
property of microtubules in suspension.
| [
{
"version": "v1",
"created": "Mon, 2 Mar 1998 19:25:03 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mavromatos",
"N. E.",
""
],
[
"Nanopoulos",
"D. V.",
""
],
[
"Samaras",
"I.",
""
],
[
"Zioutas",
"K.",
""
]
] |
quant-ph/9803006 | Chau Hoi Fung | Hoi-Kwong Lo and H. F. Chau | Unconditional Security Of Quantum Key Distribution Over Arbitrarily Long
Distances | This reprint version contains the same material as the one published
in Science 283, 2050-2056 (1999). We also include the refereed supplementary
Notes (as in http://www.sciencemag.org/feature/data/984035.shl) explicitly in
the appendix for easy reference | Science 283 (1999) 2050-2056 | 10.1126/science.283.5410.2050 | null | quant-ph | null | Quantum key distribution is widely thought to offer unconditional security in
communication between two users. Unfortunately, a widely accepted proof of its
security in the presence of source, device and channel noises has been missing.
This long-standing problem is solved here by showing that, given fault-tolerant
quantum computers, quantum key distribution over an arbitrarily long distance
of a realistic noisy channel can be made unconditionally secure. The proof is
reduced from a noisy quantum scheme to a noiseless quantum scheme and then from
a noiseless quantum scheme to a noiseless classical scheme, which can then be
tackled by classical probability theory.
| [
{
"version": "v1",
"created": "Tue, 3 Mar 1998 03:18:11 GMT"
},
{
"version": "v2",
"created": "Fri, 22 May 1998 08:58:59 GMT"
},
{
"version": "v3",
"created": "Sat, 23 May 1998 03:06:46 GMT"
},
{
"version": "v4",
"created": "Thu, 28 Jan 1999 10:56:08 GMT"
},
{
"version": "v5",
"created": "Mon, 6 Dec 1999 05:32:12 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Lo",
"Hoi-Kwong",
""
],
[
"Chau",
"H. F.",
""
]
] |
quant-ph/9803007 | Chau Hoi Fung | M. Ardehali, H. F. Chau and Hoi-Kwong Lo | Efficient Quantum Key Distribution | Minor revisions for clarification. One author dropped | null | null | null | quant-ph | null | We devise a simple modification that essentially doubles the efficiency of a
well-known quantum key distribution scheme proposed by Bennett and Brassard
(BB84). Our scheme assigns significantly different probabilities for the
different polarization bases during both transmission and reception to reduce
the fraction of discarded data. The actual probabilities used in the scheme are
announced in public. As the number of transmitted signals increases, the
efficiency of our scheme can be made to approach 100%. An eavesdropper may try
to break such a scheme by eavesdropping mainly along the predominant basis. To
defeat such an attack, we perform a refined analysis of accepted data: Instead
of lumping all the accepted data together to estimate a single error rate, we
separate the accepted data into various subsets according to the basis employed
and estimate an error rate for each subset {\it individually}.
| [
{
"version": "v1",
"created": "Tue, 3 Mar 1998 03:18:42 GMT"
},
{
"version": "v2",
"created": "Fri, 22 May 1998 09:02:50 GMT"
},
{
"version": "v3",
"created": "Sat, 23 May 1998 03:06:22 GMT"
},
{
"version": "v4",
"created": "Fri, 29 Jan 1999 06:53:55 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ardehali",
"M.",
""
],
[
"Chau",
"H. F.",
""
],
[
"Lo",
"Hoi-Kwong",
""
]
] |
quant-ph/9803008 | Ilki Kim | Guenter Mahler and Ilki Kim | Correlation between Correlations: Process and Time in Quantum Networks | presented at the 1st NASA International Conference on Quantum
Computing and Quantum Communications | null | null | Lecture Notes in Computer Science 1998 (Springer Verlag) | quant-ph | null | We study a special inhomogeneous quantum network consisting of a ring of $M$
pseudo-spins (here $M = 4$) sequentially coupled to one and the same central
spin under the influence of given pulse sequences (quantum gate operations).
This architecture could be visualized as a quantum Turing machine with a cyclic
``tape''. Rather than input-output-relations we investigate the resulting
process, i.e. the correlation between one- and two-point expectation values
(``correlations'') over various time-steps. The resulting spatio-temporal
pattern exhibits many non-classical features including Zeno-effects, violation
of temporal Bell-inequalities, and quantum parallelism. Due to the strange web
of correlations being built-up, specific measurement outcomes for the tape may
refer to one or several preparation histories of the head. Specific families of
correlation functions are more stable with respect to dissipation than the
total wave-function.
| [
{
"version": "v1",
"created": "Wed, 4 Mar 1998 09:15:31 GMT"
},
{
"version": "v2",
"created": "Sat, 6 Feb 1999 22:36:31 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mahler",
"Guenter",
""
],
[
"Kim",
"Ilki",
""
]
] |
quant-ph/9803009 | Mark Fannes | F. Benatti, M. Fannes | Statistics and Quantum Chaos | 12 pages, LateX, no figures, restructured version | null | 10.1088/0305-4470/31/46/004 | KUL-TF-98/11 | quant-ph | null | We use multi-time correlation functions of quantum systems to construct
random variables with statistical properties that reflect the degree of
complexity of the underlying quantum dynamics.
| [
{
"version": "v1",
"created": "Wed, 4 Mar 1998 10:33:25 GMT"
},
{
"version": "v2",
"created": "Thu, 26 Nov 1998 14:32:45 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Benatti",
"F.",
""
],
[
"Fannes",
"M.",
""
]
] |
quant-ph/9803010 | S. M. Apenko | S. M. Apenko | Weakly bound states in 2+\epsilon dimensions | Typeset using REVTEX, 11 pages | J.Phys.A31:1553-1562,1998 | 10.1088/0305-4470/31/6/007 | null | quant-ph nucl-th | null | We study the critical behaviour near the threshold where a first bound state
appears at some value of coupling constant in an attractive short-range
potential in $2+\epsilon $ dimensions. We obtain general expression for the
binding energy near the threshold and also demonstrate that the critical region
is correctly described by an effective separable potential. The critical
exponent of the radius of weakly bound state is shown to coincide with the
correlation length exponent for the spin model in the large-N limit. In two
dimensions, where the binding energy is exponentially small in coupling
constant, we obtain a general analytic expression for the prefactor.
| [
{
"version": "v1",
"created": "Wed, 4 Mar 1998 12:27:35 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Apenko",
"S. M.",
""
]
] |
quant-ph/9803011 | Christian Mrugalla | H. D. Doebner | Remarks on a Nonlinear Quantum Theory | LaTeX, 5 pages, no figures, Proc. 5th Wigner Symposium (to appear) | null | null | ASI-TPA/02/98 | quant-ph | null | Motivated by recent proposals (Bialynicki-Birula, Mycielski; Haag, Bannier;
Weinberg; Doebner, Goldin) for nonlinear quantum mechanical evolution equations
for pure states some principal difficulties in the framework of usual quantum
theory, which is based on its inherent linear structure, are discussed. A
generic construction of nonlinear evolution equations through nonlinear gauge
transformations is indicated.
| [
{
"version": "v1",
"created": "Wed, 4 Mar 1998 15:21:32 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Doebner",
"H. D.",
""
]
] |
quant-ph/9803012 | Riccardo Giannitrapani | Riccardo Giannitrapani | Quantum Coordinates of an Event in Local Quantum Physics | 6 pages, LaTeX, no figures | J.Math.Phys. 39 (1998) 5180-5182 | 10.1063/1.532564 | UTF-411 | quant-ph | null | Recently it has been proposed, using the formalism of
positive-operator-valued measures, a possible definition of quantum coordinates
for events in the context of quantum mechanics. In this short note we analyze
this definition from the point of view of local algebras in the framework of
local quantum theories.
| [
{
"version": "v1",
"created": "Wed, 4 Mar 1998 16:09:16 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Giannitrapani",
"Riccardo",
""
]
] |
quant-ph/9803013 | Elisabetta Sassaroli | A. Widom, E. Sassaroli, Y. N. Srivastava and J. Swain | The Casimir Effect and Thermodynamic Instability | Tex File 4 pages | null | null | MIT-CTP-2721 | quant-ph | null | One loop field theory calculations of free energies quite often yield
violations of the stability conditions associated with the thermodynamic second
law. Perhaps the best known example involves the equation of state of black
holes. Here, it is pointed out that the Casimir force between two parallel
conducting plates also violates a thermodynamic stability condition normally
associated with the second law of thermodynamics.
| [
{
"version": "v1",
"created": "Wed, 4 Mar 1998 22:05:12 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Widom",
"A.",
""
],
[
"Sassaroli",
"E.",
""
],
[
"Srivastava",
"Y. N.",
""
],
[
"Swain",
"J.",
""
]
] |
quant-ph/9803014 | Alec Maassen van den Brink | K. C. Ho, P. T. Leung, Alec Maassen van den Brink and K. Young | Second-quantization of open systems using quasinormal modes | 26 p., 2 figs, REVTeX 3.0 with LaTeX 2.09, submitted to Phys. Rev. E | Phys.Rev. E58 (1998) 2965-2978 | 10.1103/PhysRevE.58.2965 | null | quant-ph | null | The second-quantization of a scalar field in an open cavity is formulated,
from first principles, in terms of the quasinormal modes (QNMs), which are the
eigensolutions of the evolution equation that decay exponentially in time as
energy leaks to the outside. This formulation provides a description involving
the cavity degrees of freedom only, with the outside acting as a (thermal or
driven) source. Thermal correlation functions and cavity Feynman propagators
are thus expressed in terms of the QNMs, labeled by a discrete index rather
than a continuous momentum. Single-resonance domination of the density of
states and the spontaneous decay rate is then given a proper foundation. This
is a first essential step towards the application of QNMs to cavity QED
phenomena, to be reported elsewhere.
| [
{
"version": "v1",
"created": "Thu, 5 Mar 1998 06:50:28 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Ho",
"K. C.",
""
],
[
"Leung",
"P. T.",
""
],
[
"Brink",
"Alec Maassen van den",
""
],
[
"Young",
"K.",
""
]
] |
quant-ph/9803015 | Matteo G. A. Paris | Giacomo M. D'Ariano, Matteo G. A. Paris and Massimiliano F. Sacchi
(Quantum Optics Group -- University of Pavia) | Generation of phase-coherent states | To appear in PRA -- More info at http://enterprise.pv.infn.it/ | Phys.Rev. A57 (1998) 4894-4898 | 10.1103/PhysRevA.57.4894 | null | quant-ph | null | An interaction scheme involving nonlinear $\chi^{(2)}$ media is suggested for
the generation of phase-coherent states (PCS). The setup is based on parametric
amplification of vacuum followed by up-conversion of the resulting twin-beam.
The involved nonlinear interactions are studied by the exact numerical
diagonalization. An experimentally achievable working regime to approximate PCS
with high conversion rate is given, and the validity of parametric
approximation is discussed.
| [
{
"version": "v1",
"created": "Thu, 5 Mar 1998 10:32:31 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"D'Ariano",
"Giacomo M.",
"",
"Quantum Optics Group -- University of Pavia"
],
[
"Paris",
"Matteo G. A.",
"",
"Quantum Optics Group -- University of Pavia"
],
[
"Sacchi",
"Massimiliano F.",
"",
"Quantum Optics Group -- University of Pavia"
]
] |
quant-ph/9803016 | Hagen Kleinert | H. Kleinert and A. Chervyakov | Simple Explicit Formulas for Gaussian Path Integrals with Time-Dependent
Frequencies | Author Information under
http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of
paper also at
http://www.physik.fu-berlin.de/~kleinert/kleiner_re263/preprint.html | Phys.Lett. A245 (1998) 345-357 | 10.1016/S0375-9601(98)00380-6 | null | quant-ph hep-th | null | Quadratic fluctuations require an evaluation of ratios of functional
determinants of second-order differential operators. We relate these ratios to
the Green functions of the operators for Dirichlet, periodic and antiperiodic
boundary conditions on a line segment. This permits us to take advantage of
Wronski's construction method for Green functions without knowledge of
eigenvalues. Our final formula expresses the ratios of functional determinants
in terms of an ordinary $2\times2$ -determinant of a constant matrix
constructed from two linearly independent solutions of a the homogeneous
differential equations associated with the second-order differential operators.
For ratios of determinants encountered in semiclassical fluctuations around a
classical solution, the result can further be expressed in terms of this
classical solution.
In the presence of a zero mode, our method allows for a simple universal
regularization of the functional determinants. For Dirichlet's boundary
condition, our result is equivalent to Gelfand-Yaglom's.
Explicit formulas are given for a harmonic oscillator with an arbitrary
time-dependent frequency.
| [
{
"version": "v1",
"created": "Thu, 5 Mar 1998 16:17:24 GMT"
},
{
"version": "v2",
"created": "Fri, 10 Jul 1998 08:38:48 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Kleinert",
"H.",
""
],
[
"Chervyakov",
"A.",
""
]
] |
quant-ph/9803017 | Chiara Macchiavello | J.I. Cirac, A. Ekert, S.F. Huelga and C. Macchiavello | Distributed Quantum Computation over Noisy Channels | 8 pages (revtex), 3 figures; manuscript extended, figures added | null | 10.1103/PhysRevA.59.4249 | null | quant-ph | null | We analyse the use of entangled states to perform quantum computations non
locally among distant nodes in a quantum network. The complexity associated
with the generation of multiparticle entangled states is quantified in terms of
the concept of global cost. This parameter allows us to compare the use of
physical resources in different schemes. We show that for ideal channels and
for a sufficiently large number of nodes, the use of maximally entangled states
is advantageous over uncorrelated ones. For noisy channels, one has to use
entanglement purification procedures in order to create entangled states of
high fidelity. We show that under certain circumstances a quantum network
supplied with a maximally entangled input still yields a smaller global cost,
provided that $n$ belongs to a given interval $n\in [n_{min},n_{max}]$. The
values of $n_{min}$ and $n_{max}$ crucially depend on the purification
protocols used to establish the $n$-- processor entangled states, as well as on
the presence of decoherence processes during the computation. The phase
estimation problem has been used to illustrate this fact.
| [
{
"version": "v1",
"created": "Fri, 6 Mar 1998 09:01:43 GMT"
},
{
"version": "v2",
"created": "Thu, 14 Jan 1999 13:04:02 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Cirac",
"J. I.",
""
],
[
"Ekert",
"A.",
""
],
[
"Huelga",
"S. F.",
""
],
[
"Macchiavello",
"C.",
""
]
] |
quant-ph/9803018 | Jeeva S. Anadan | Y. Aharonov and J. Anandan | Meaning of the Density Matrix | 12 pages, latex, no figures, paper presented at the International
Symposium on UNCERTAIN REALITY, New Delhi, India, Jan. 5-9, 1998 | null | null | null | quant-ph | null | Protective measurement, which was proposed as a method of observing the
wavefunction of a single system, is extended to the observation of the density
matrix of a single system. d'Espagnat's definition of `proper mixture' is shown
to be improper because it does not allow for appropriate fluctuations. His
claim that there could be different mixtures corresponding to the same density
matrix is critically examined. These results provide a new meaning to the
density matrix, which gives it the same ontological status as the wavefunction
describing a pure state. This also enables quantum entropy to be associated
with a single system.
| [
{
"version": "v1",
"created": "Sun, 8 Mar 1998 09:48:03 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Aharonov",
"Y.",
""
],
[
"Anandan",
"J.",
""
]
] |
quant-ph/9803019 | M. Czachor | Marek Czachor | Local modification of the Abrams-Lloyd nonlinear algorithm | revtex, submitted to PRA (Rapid. Comm.) | null | null | null | quant-ph | null | The nonlinear algorithms proposed recently by Abrams and Lloyd [Report No.
quant-ph/9801041] are fast but make an explicit use of an arbitrarily fast
unphysical transfer of information within a quantum computer. It is shown that
there exists a simplification of the second Abrams-Lloyd algorithm which
eliminates the unphysical effect but keeps the algorithm fast.
| [
{
"version": "v1",
"created": "Mon, 9 Mar 1998 11:27:10 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Czachor",
"Marek",
""
]
] |
quant-ph/9803020 | Taksu Cheon de Caracorum | Taksu Cheon (Kochi Tech) | Double Spiral Energy Surface in One-dimensional Quantum Mechanics of
Generalized Pointlike Potentials | 4 pages ReVTeX 4 epsf figures included, correction expanded refs | Physics Letters A 248 (1998) 285-289 | 10.1016/S0375-9601(98)00725-7 | null | quant-ph cond-mat nlin.SI nucl-th solv-int | null | We analyze the eigenvalue problem of a quantum particle on the line with the
generalized pointlike potential of three parameter family. It is shown that the
energy surface in the parameter space has a set of singularities, around which
different eigenstates are connected in the form of paired spiral stairway. An
examplar wave-function aholonomy is displayed where the ground state is
adiabatically turned into the second excited state after cyclic rotation in the
parameter space.
KEYWORDS: one-dimensional system, $\delta'$ potential, non-trivial topology
in quantum mechanics, exotic wave-function aholonomy
| [
{
"version": "v1",
"created": "Tue, 10 Mar 1998 01:50:19 GMT"
},
{
"version": "v2",
"created": "Sun, 15 Mar 1998 06:46:09 GMT"
},
{
"version": "v3",
"created": "Sun, 10 May 1998 10:58:48 GMT"
}
] | 2009-02-27T00:00:00 | [
[
"Cheon",
"Taksu",
"",
"Kochi Tech"
]
] |
quant-ph/9803021 | Elcio Abdalla | E. Abdalla and R. Banerjee | Quantization of the multidimensional rotor | latex, 12 pages | Braz.J.Phys. 31 (2001) 80-83 | null | null | quant-ph | null | We reconsider the problem of quantising a particle on the $D$-dimensional
sphere. Adopting a Lagrangian method of reducing the degrees of freedom, the
quantum Hamiltonian is found to be the usual Schr\"odinger operator without any
boundary term. The equivalence with the Dirac Hamiltonian approach is
demonstrated, either in the cartesian or in the curvilinear basis. We also
briefly comment on the path integral approach.
| [
{
"version": "v1",
"created": "Tue, 10 Mar 1998 12:21:25 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Abdalla",
"E.",
""
],
[
"Banerjee",
"R.",
""
]
] |
quant-ph/9803022 | Michael G. Moore | M. G. Moore and P. Meystre (Optical Sciences Center and Department of
Physics, University of Arizona, Tucson, AZ 85721) | Effects of atomic diffraction on the Collective Atomic Recoil Laser | plain tex, 10 pages, 10 figures | null | 10.1103/PhysRevA.58.3248 | null | quant-ph | null | We formulate a wave atom optics theory of the Collective Atomic Recoil Laser,
where the atomic center-of-mass motion is treated quantum mechanically. By
comparing the predictions of this theory with those of the ray atom optics
theory, which treats the center-of-mass motion classically, we show that for
the case of a far off-resonant pump laser the ray optics model fails to predict
the linear response of the CARL when the temperature is of the order of the
recoil temperature or less. This is due to the fact that in theis temperature
regime one can no longer ignore the effects of matter-wave diffraction on the
atomic center-of-mass motion.
| [
{
"version": "v1",
"created": "Wed, 11 Mar 1998 00:46:21 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Moore",
"M. G.",
"",
"Optical Sciences Center and Department of\n Physics, University of Arizona, Tucson, AZ 85721"
],
[
"Meystre",
"P.",
"",
"Optical Sciences Center and Department of\n Physics, University of Arizona, Tucson, AZ 85721"
]
] |
quant-ph/9803023 | Brian King | B. E. King, C. S. Wood, C. J. Myatt, Q. A. Turchette, D. Leibfried, W.
M. Itano, C. Monroe, and D. J. Wineland | Cooling the Collective Motion of Trapped Ions to Initialize a Quantum
Register | 5 pages, including 3 figures. RevTeX. PDF and PostScript available at
http://www.bldrdoc.gov/timefreq/ion/qucomp/papers.htm . final (published)
version. Eq. 1 and Table 1 slightly different from original submission | Phys. Rev. Lett., Vol. 81, pp. 1525-1528 (1998) | 10.1103/PhysRevLett.81.1525 | null | quant-ph | null | We report preparation in the ground state of collective modes of motion of
two trapped 9Be+ ions. This is a crucial step towards realizing quantum logic
gates which can entangle the ions' internal electronic states. We find that
heating of the modes of relative ion motion is substantially suppressed
relative to that of the center-of-mass modes, suggesting the importance of
these modes in future experiments.
| [
{
"version": "v1",
"created": "Wed, 11 Mar 1998 01:07:53 GMT"
},
{
"version": "v2",
"created": "Fri, 13 Mar 1998 21:03:12 GMT"
},
{
"version": "v3",
"created": "Tue, 26 May 1998 17:28:30 GMT"
},
{
"version": "v4",
"created": "Thu, 20 Aug 1998 17:31:35 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"King",
"B. E.",
""
],
[
"Wood",
"C. S.",
""
],
[
"Myatt",
"C. J.",
""
],
[
"Turchette",
"Q. A.",
""
],
[
"Leibfried",
"D.",
""
],
[
"Itano",
"W. M.",
""
],
[
"Monroe",
"C.",
""
],
[
"Wineland",
"D. J.",
""
]
] |
quant-ph/9803024 | Georg Junker | Georg Junker and Pinaki Roy | Conditionally exactly solvable potentials: A supersymmetric construction
method | 24 pages, 11 figures, LaTeX209, amsfonts | Annals Phys. 270 (1998) 155-177 | 10.1006/aphy.1998.5856 | null | quant-ph | null | We present in this paper a rather general method for the construction of
so-called conditionally exactly solvable potentials. This method is based on
algebraic tools known from supersymmetric quantum mechanics. Various families
of one-dimensional potentials are constructed whose corresponding Schr\"odinger
eigenvalue problem can be solved exactly under certain conditions of the
potential parameters. Examples of quantum systems on the real line, the half
line as well as on some finite interval are studied in detail.
| [
{
"version": "v1",
"created": "Wed, 11 Mar 1998 17:13:04 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Junker",
"Georg",
""
],
[
"Roy",
"Pinaki",
""
]
] |
quant-ph/9803025 | Rodolfo Gambini | Rodolfo Gambini | The Measurement Problem and the Reduction Postulate of Quantum Mechanics | 5 pages, Revtex, no figures, minor changes and comments added | null | null | IFFI-05-98 | quant-ph gr-qc | null | It is well known, that the causal Schr\"odinger evolution of a quantum state
is not compatible with the reduction postulate, even when decoherence is taken
into account. The violation of the causal evolution, introduced by the standard
reduction postulate distinguishes certain systems (as the measurement devices),
whose states are very close to statistical mixtures (as the ones resulting from
the process of decoherence). In these systems, this violation has not any
observable effect. In arbitrary quantum systems, the transition from the
initial density matrix to a diagonal matrix predicted by the standard reduction
postulate, would lead to a complete breakdown of the Schr\"odinger evolution,
and consequently would destroy all the predictive power of quantum mechanics.
What we show here, is that there is a modified version of the postulate that
allows to treat all the quantum mechanical systems on equal footing. The
standard reduction postulate may be considered as a good approximation, useful
for practical purposes, of this modified version which is consistent with the
Schr\"odinger evolution and via decoherence with the experimental results.
Within this approach, the physical role played by the reduction postulate is as
a tool for the computation of relative probabilities and consequently for the
determination of the probabilities of consistent histories.
| [
{
"version": "v1",
"created": "Wed, 11 Mar 1998 18:50:28 GMT"
},
{
"version": "v2",
"created": "Thu, 18 Jun 1998 20:01:35 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gambini",
"Rodolfo",
""
]
] |
quant-ph/9803026 | Frank Gaitan | Frank Gaitan | Berry's Phase in the Presence of a Stochastically Evolving Environment:
A Geometric Mechanism for Energy-Level Broadening | 29 pages, RevTex, submitted to Phys. Rev. A | null | 10.1103/PhysRevA.58.1665 | BC-FPG-123 | quant-ph cond-mat hep-th | null | The generic Berry phase scenario in which a two-level system is coupled to a
second system whose dynamical coordinate is slowly-varying is generalized to
allow for stochastic evolution of the slow system. The stochastic behavior is
produced by coupling the slow system to a heat resevoir which is modeled by a
bath of harmonic oscillators initially in equilibrium at temperature T, and
whose spectral density has a bandwidth which is small compared to the
energy-level spacing of the fast system. The well-known energy-level shifts
produced by Berry's phase in the fast system, in conjunction with the
stochastic motion of the slow system, leads to a broadening of the fast system
energy-levels. In the limit of strong damping and sufficiently low temperature,
we determine the degree of level-broadening analytically, and show that the
slow system dynamics satisfies a Langevin equation in which Lorentz-like and
electric-like forces appear as a consequence of geometrical effects. We also
determine the average energy-level shift produced in the fast system by this
mechanism.
| [
{
"version": "v1",
"created": "Thu, 12 Mar 1998 00:10:22 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Gaitan",
"Frank",
""
]
] |
quant-ph/9803027 | null | Vladimir S. Mashkevich (Institute of Physics, Kiev) | Another Comment on ``Quantum Entanglement and Nonexistence of
Superluminal Signals'' | 4 pages, LATEX 2.09 | null | null | null | quant-ph | null | We argue that the claim given in quant-ph/9801014 remains untenable in the
revised version. The fallacy in the proof is a misinterpretation of the
no-cloning and teleportation theorems, which do not involve time and reference
frames.
| [
{
"version": "v1",
"created": "Thu, 12 Mar 1998 15:34:03 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mashkevich",
"Vladimir S.",
"",
"Institute of Physics, Kiev"
]
] |
quant-ph/9803028 | Erasmo Recami | W.A. Rodrigues Jr., Jayme Vaz and Erasmo Recami | Generalization of Dirac Non-Linear Electrodynamics, and Spinning Charged
Particles | standard LaTeX file; 16 pages; it is a corrected version of a paper
appeared in Found. Phys. (issue in honour of A.O.Barut) 23 (1993) 469 | Found.Phys. 23 (1993) 469-485 | 10.1007/BF01883725 | null | quant-ph | null | In this note we generalized the Dirac non-linear electrodynamics, by
introducing two potentials (namely, the vector potential A and the
pseudo-vector potential gamma^5 B of the electromagnetic theory with charges
and magnetic monopoles) and by imposing the pseudoscalar part of the product
omega.omega* to be zero, with omega = A + gamma^5 B. We show that the field
equations of such a theory possess a soliton-like solution which can represent
a priori a "charged particle", since it is endowed with a Coulomb field plus
the field of a magnetic dipole. The rest energy of the soliton is finite, and
the angular momentum stored in its electromagnetic field can be identified
--for suitable choices of the parameters-- with the spin of the charged
particle. Thus this approach seems to yield a classical model for the charged
(spinning) particle, which does not meet the problems met by earlier attempts
in the same direction.
| [
{
"version": "v1",
"created": "Thu, 12 Mar 1998 15:45:10 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Rodrigues",
"W. A.",
"Jr."
],
[
"Vaz",
"Jayme",
""
],
[
"Recami",
"Erasmo",
""
]
] |
quant-ph/9803029 | O. Rosas | J. Oscar Rosas-Ortiz | New Families of Isospectral Hydrogen-like potentials | 8 pages, LaTex, 2 PostScript figures. Minor changes, figures added | J. Phys. A: Math. Gen. 31 (1998) L507-L513 | 10.1088/0305-4470/31/27/003 | null | quant-ph physics.atom-ph | null | By applying algebraic techniques, we construct a two-parametric family of
strictly isospectral Hydrogen-like potentials as well as some of its
one-parametric limits. An additional one-parametric almost isospectral family
of Hydrogen-like potentials is also investigated. It is argued that the
construction of a SUSY partner Hamiltonian using a factorization energy
$\delta$ less than the ground state energy of the departure Hamiltonian is
unnecessarily restrictive.
| [
{
"version": "v1",
"created": "Thu, 12 Mar 1998 22:17:09 GMT"
},
{
"version": "v2",
"created": "Sat, 14 Mar 1998 14:15:40 GMT"
}
] | 2008-10-13T00:00:00 | [
[
"Rosas-Ortiz",
"J. Oscar",
""
]
] |
quant-ph/9803030 | Steven J. van Enk | S.J. van Enk | No-cloning and superluminal signaling | 2 pages, no figures | null | null | null | quant-ph | null | The argument given by M.D. Westmoreland and B. Schumacher in quant-ph/9801014
leading to the purported conclusion that superluminal signaling violates the
no-cloning theorem is shown to be incorrect.
| [
{
"version": "v1",
"created": "Fri, 13 Mar 1998 02:17:57 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"van Enk",
"S. J.",
""
]
] |
quant-ph/9803031 | Stefan Scheel | S. Scheel, L. Knoell, D.-G. Welsch | QED commutation relations for inhomogeneous Kramers-Kronig dielectrics | 15 pages | null | 10.1103/PhysRevA.58.700 | FSUJ TPI QO-05/98 | quant-ph | null | Recently a quantization scheme for the phenomenological Maxwell theory of the
full electromagnetic field in an inhomogeneous three-dimensional, dispersive,
and absorbing dielectric medium has been developed and applied to a system
consisting of two infinite half-spaces with a common planar interface (H.T.
Dung, L. Knoell, and D.-G. Welsch, Phys. Rev. A 57, in press). Here we show
that the scheme, which is based on the classical Green-tensor integral
representation of the electromagnetic field, applies to any inhomogeneous
medium. For this purpose we prove that the fundamental equal-time commutation
relations of QED are preserved for an arbitrarily space-dependent,
Kramers--Kronig consistent permittivity. Further, an extension of the
quantization scheme to linear media with bounded regions of amplification is
given, and the problem of anisotropic media is briefly addressed.
| [
{
"version": "v1",
"created": "Fri, 13 Mar 1998 15:32:57 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Scheel",
"S.",
""
],
[
"Knoell",
"L.",
""
],
[
"Welsch",
"D. -G.",
""
]
] |
quant-ph/9803032 | Cesar Flores | J. C. Flores (Universidad de Tarapaca, Arica, Chile) | Decoherence from internal degrees of freedom for cluster of
mesoparticles : a hierarchy of master equations | 19 pages, 0 figures, latex | J.Phys.A31:8623-8633,1998 | 10.1088/0305-4470/31/43/006 | 3-98 UTA | quant-ph | null | A mesoscopic evolution equation for an ensemble of mesoparticles follows
after the elimination of internal degrees of freedom. If the system is composed
of a hierarchy of scales, the reduction procedure could be worked repeatedly
and the characterization of this iterating method is carried out. Namely, a
prescription describing a discrete hierarchy of master equations for the
density operator is obtained. Decoherence follows from the irreversible
coupling of the systems, defined by mesoscopic variables, to internal degrees
of freedom. We discuss briefly the existence of systems with the same dynamics
laws at different scales. We made an explicit calculation for an ensemble of
particles with internal harmonic interaction in an external anharmonic field.
New conditions related to the semiclassical limit for mesoscopic systems
(Wigner-function) are conjectured.
| [
{
"version": "v1",
"created": "Fri, 13 Mar 1998 20:14:16 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Flores",
"J. C.",
"",
"Universidad de Tarapaca, Arica, Chile"
]
] |
quant-ph/9803033 | Ashish Thapliyal | David P. DiVincenzo (IBM Research), Christopher A. Fuchs (Caltech),
Hideo Mabuchi (Caltech), John A. Smolin (IBM Research), Ashish Thapliyal
(UCSB), Armin Uhlmann (Uni. Leipzig) | Entanglement of Assistance | 11 pages, LaTeX w/llncs style. To appear in Proceedings of the 1st
NASA International Conference on Quantum Computing and Quantum
Communication(Springer-Verlag) | null | null | null | quant-ph | null | The newfound importance of ``entanglement as a resource'' in quantum
computation and quantum communication compels us to quantify it in as many
distinct ways as possible. Here we explore a new measure of entanglement for
mixed quantum states of bipartite systems, which we name the Entanglement of
Assistance. We show it to be the maximum average entanglement of all pure-state
ensembles consistent with the given density matrix. In this sense, the
Entanglement of Assistance is a quantity directly dual to the more standard
Entanglement of Formation. With the help of lower and upper bounds, we
calculate the Entanglement of Assistance for a few cases and use these results
to show that it possesses the surprising property of superadditivity. We
believe that this may shed some light on the question of additivity for the
Entanglement of Formation.
| [
{
"version": "v1",
"created": "Sun, 15 Mar 1998 22:02:35 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"DiVincenzo",
"David P.",
"",
"IBM Research"
],
[
"Fuchs",
"Christopher A.",
"",
"Caltech"
],
[
"Mabuchi",
"Hideo",
"",
"Caltech"
],
[
"Smolin",
"John A.",
"",
"IBM Research"
],
[
"Thapliyal",
"Ashish",
"",
"UCSB"
],
[
"Uhlmann",
"Armin",
"",
"Uni. Leipzig"
]
] |
quant-ph/9803034 | null | Guang-jiong Ni (Department of Physics, Fudan University and Shanghai,
200433, P. R. China) | To Enjoy the Morning Flower in the Evening -- Is Special Relativity a
Classical Theory? | 13 pages, LaTex, no figure | Kexue (Science) Vol. 50, No. 1, 29-33 (1998) (English translation) | null | null | quant-ph | null | The relation between the special relativity and quantum mechanics is
discussed. Based on the postulate that space-time inversion is equavalent to
particle-antiparticle transformation, the essence of special relativity is
explored and the relativistic modification on Stationary Schr\"{o}dinger
Equation is derived.
| [
{
"version": "v1",
"created": "Sat, 14 Mar 1998 03:56:24 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ni",
"Guang-jiong",
"",
"Department of Physics, Fudan University and Shanghai,\n 200433, P. R. China"
]
] |
quant-ph/9803035 | Alejandro Rivero | Alejandro Rivero (U. de Zaragoza) | A short derivation of Feynman formula | 3 pages, LaTeX | null | null | null | quant-ph | null | The complex exponential weighting of Feynman formalism is seen to happen at
the classical level. (Finiteness of) Feynman path integral formula is suspected
then to appear as a consistency condition for the existence of certain Dirac
measures over functional spaces.
| [
{
"version": "v1",
"created": "Sat, 14 Mar 1998 12:40:06 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rivero",
"Alejandro",
"",
"U. de Zaragoza"
]
] |
quant-ph/9803036 | Erasmo Recami | M. Pavsic, Erasmo Recami and W.A. Rodrigues Jr | Electron structure, Zitterbewegung, and the new non-linear Dirac-like
equation | LaTeX; 19 pages; this is a corrected version of work appeared partly
in Hadronic J. 18 (1995) 97 and partly in Phys.Lett. B318 (1993) 481 | Hadronic J.18:98,1995; Phys.Lett.B318:481-488,1993 | 10.1016/0370-2693(93)91543-V | null | quant-ph | null | The recent literature shows a renewed interest, with various independent
approaches, in the classical theories for spin. Considering the possible
interest of those results, at least for the electron case, we purpose in this
paper to explore their physical and mathematical meaning, by the natural and
powerful language of Clifford algebras (which, incidentally, will allow us to
unify those different approaches). In such theories, the ordinary electron is
in general associated to the mean motion of a point-like "constituent" Q, whose
trajectory is a cylindrical helix. We find, in particular, that the object Q
obeys a new, non-linear Dirac-like equation, such that --when averaging over an
internal cycle (which corresponds to linearization)-- it transforms into the
ordinary Dirac equation (valid for the electron as a whole).
| [
{
"version": "v1",
"created": "Sat, 14 Mar 1998 17:05:30 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Pavsic",
"M.",
""
],
[
"Recami",
"Erasmo",
""
],
[
"Rodrigues",
"W. A.",
"Jr"
]
] |
quant-ph/9803037 | Erasmo Recami | W.A.Rodrigues Jr., Jayme Vaz, Erasmo Recami and G.Salesi | About Zitterbewegung and electron structure | LaTeX; 11 pages; this is a corrected version of work appeared partly
in Phys. Lett. B318 (1993) 623 and partly in "Particles, Gravity and
Space-Time" (ed.by P.I.Pronin & G.A.Sardanashvily; World Scient., Singapore,
1996), p.345 | Phys.Lett.B318:623-628,1993 | 10.1016/0370-2693(93)90464-S | null | quant-ph | null | We start from the spinning electron theory by Barut and Zanghi, which has
been recently translated into the Clifford algebra language. We "complete" such
a translation, first of all, by expressing in the Clifford formalism a
particular Barut-Zanghi (BZ) solution, which refers (at the classical limit) to
an internal helical motion with a time-like speed [and is here shown to
originate from the superposition of positive and negative frequency solutions
of the Dirac equation]. Then, we show how to construct solutions of the Dirac
equation describing helical motions with light-like speed, which meet very well
the standard interpretation of the velocity operator in the Dirac equation
theory (and agree with the solution proposed by Hestenes, on the basis
--however-- of ad-hoc assumptions that are unnecessary in the present
approach). The above results appear to support the conjecture that the
Zitterbewegung motion (a helical motion, at the classical limit) is responsible
for the electron spin.
| [
{
"version": "v1",
"created": "Sat, 14 Mar 1998 17:08:48 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Rodrigues",
"W. A.",
"Jr."
],
[
"Vaz",
"Jayme",
""
],
[
"Recami",
"Erasmo",
""
],
[
"Salesi",
"G.",
""
]
] |
quant-ph/9803038 | Victor M. Perez Garcia | Victor M. Perez-Garcia, H. Michinel, H. Herrero | Bose--Einstein solitons in highly asymmetric traps | 12 pages, Latex, Figures available under request on
[email protected] | Phys.Rev. A57 (1998) 5 | 10.1103/PhysRevA.57.3837 | null | quant-ph | null | We obtain analytic solutions to the Gross-Pitaevskii equation with negative
scattering length in highly asymmetric traps. We find that in these traps the
Bose--Einstein condensates behave like quasiparticles and do not expand when
the trapping in one direction is eliminated. The results can be applicable to
the control of the motion of Bose--Einstein condensates.
| [
{
"version": "v1",
"created": "Sat, 14 Mar 1998 19:05:10 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Perez-Garcia",
"Victor M.",
""
],
[
"Michinel",
"H.",
""
],
[
"Herrero",
"H.",
""
]
] |
quant-ph/9803039 | Diosi Lajos | Lajos Diosi | Relativistic formulation of quantum state diffusion? | 5 pages LaTeX, submitted to J. Phys. A | J.Phys.A31:9601-9603,1998 | 10.1088/0305-4470/31/47/019 | null | quant-ph | null | The recently reported relativistic formulation of the well-known
non-relativistic quantum state diffusion is seriously mistaken. It predicts,
for instance, inconsistent measurement outcomes for the same system when seen
by two different inertial observers.
| [
{
"version": "v1",
"created": "Sat, 14 Mar 1998 23:18:50 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Diosi",
"Lajos",
""
]
] |
quant-ph/9803040 | Andreas Mielke | Andreas Mielke (Institut fuer Theoretische Physik, Heidelberg, F.R.
Germany) | Flow equations for band--matrices | 12 pages, one eps-figure, uses epsfig.sty. Accepted for publication
in European Physical Journal | null | 10.1007/s100510050485 | HD-TVP-98-01 | quant-ph cond-mat.stat-mech math-ph math.MP nucl-th | null | Continuous unitary transformations can be used to diagonalize or
approximately diagonalize a given Hamiltonian. In the last four years, this
method has been applied to a variety of models of condensed matter physics and
field theory. With a new generator for the continuous unitary transformation
proposed in this paper one can avoid some of the problems of former
applications. General properties of the new generator are derived. It turns out
that the new generator is especially useful for Hamiltonians with a banded
structure. Two examples, the Lipkin model, and the spin--boson model are
discussed in detail.
| [
{
"version": "v1",
"created": "Mon, 16 Mar 1998 10:12:47 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Mielke",
"Andreas",
"",
"Institut fuer Theoretische Physik, Heidelberg, F.R.\n Germany"
]
] |
quant-ph/9803041 | Mio Murao | M. Murao and P.L. Knight | Decoherence in nonclassical motional states of a trapped ion | 7 pages, 3 figures | Phys.Rev.A58:663-669,1998 | 10.1103/PhysRevA.58.663 | null | quant-ph | null | The decoherence of nonclassical motional states of a trapped $^9 {\rm Be^+}$
ion in a recent experiment is investigated theoretically. Sources of
decoherence considered here destroy the characteristic coherent quantum
dynamics of the system but do not cause energy dissipation. Here they are first
introduced phenomenologically and then described using a microscopic
Hamiltonian formulation. Theoretical predictions are compared to experimental
results.
| [
{
"version": "v1",
"created": "Mon, 16 Mar 1998 14:47:44 GMT"
}
] | 2011-08-04T00:00:00 | [
[
"Murao",
"M.",
""
],
[
"Knight",
"P. L.",
""
]
] |
quant-ph/9803042 | Salman Habib | Salman Habib, Kosuke Shizume, and Wojciech Hubert Zurek | Decoherence, Chaos, and the Correspondence Principle | 4 pages, 2 figures (color figures embedded at low resolution), uses
RevTeX plus macro (included). Phys. Rev. Lett. (in press) | Phys.Rev.Lett. 80 (1998) 4361-4365 | 10.1103/PhysRevLett.80.4361 | LA-UR-97-4643 | quant-ph | null | We present evidence that decoherence can produce a smooth
quantum-to-classical transition in nonlinear dynamical systems. High-resolution
tracking of quantum and classical evolutions reveals differences in expectation
values of corresponding observables. Solutions of master equations demonstrate
that decoherence destroys quantum interference in Wigner distributions and
washes out fine structure in classical distributions bringing the two closer
together. Correspondence between quantum and classical expectation values is
also re-established.
| [
{
"version": "v1",
"created": "Mon, 16 Mar 1998 23:37:29 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Habib",
"Salman",
""
],
[
"Shizume",
"Kosuke",
""
],
[
"Zurek",
"Wojciech Hubert",
""
]
] |
quant-ph/9803043 | null | Pedro F. Gonzalez-Diaz (IMAFF, CSIC, Spain) | On multiphoton absorption by molecules | 4 pages, RevTex, to appear in Theochem | null | null | IMAFF-RCA-98-01 | quant-ph | null | Rabi frequencies for multiphoton absorption by atoms or molecules that can be
characterized as two- or three-level systems are obtained in the cases of
single and double laser perturbations. If the ambiguity in the origin of
absolute energy is conveniently gauged off in the three-level model, there
appears an additional non linear frequency which is originated from the
separate evolution of a relative-frequency component induced in the whole
system by the simultaneous action of the two perturbations.
| [
{
"version": "v1",
"created": "Tue, 17 Mar 1998 10:52:39 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gonzalez-Diaz",
"Pedro F.",
"",
"IMAFF, CSIC, Spain"
]
] |
quant-ph/9803044 | Ian C. Percival | Ian C. Percival (Physics, QMW, London, UK) | Quantum transfer functions, weak nonlocality and relativity | Plain TeX, 12 pages, no figures. To be submitted Physics Letters A
Derivation of Bell inequality corrected (14c) + minor changes | Phys.Lett. A244 (1998) 495-501 | 10.1016/S0375-9601(98)00353-3 | QMW TH 98-10 | quant-ph | null | The method of transfer functions is developed as a tool for studying Bell
inequalities, alternative quantum theories and the associated physical
properties of quantum systems. Non-negative probabilities for transfer
functions result in Bell-type inequalities. The method is used to show that all
realistic Lorentz-invariant quantum theories, which give unique results and
have no preferred frame, can be ruled out on the grounds that they lead to weak
backward causality.
| [
{
"version": "v1",
"created": "Tue, 17 Mar 1998 14:50:06 GMT"
},
{
"version": "v2",
"created": "Mon, 23 Mar 1998 11:54:25 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Percival",
"Ian C.",
"",
"Physics, QMW, London, UK"
]
] |
quant-ph/9803045 | David Vitali | David Vitali, Paolo Tombesi and Gerard J. Milburn | Quantum State Protection in Cavities | RevTex, 9 figures, submitted to Phys. Rev. A | Phys. Rev. A vol. 57, 4930 (1998) | 10.1103/PhysRevA.57.4930 | DMF-09 | quant-ph | null | We show how an initially prepared quantum state of a radiation mode in a
cavity can be preserved for a long time using a feedback scheme based on the
injection of appropriately prepared atoms. We present a feedback scheme both
for optical cavities, which can be continuously monitored by a photodetector,
and for microwave cavities, which can be monitored only indirectly via the
detection of atoms that have interacted with the cavity field. We also discuss
the possibility of applying these methods for decoherence control in quantum
information processing.
| [
{
"version": "v1",
"created": "Tue, 17 Mar 1998 15:27:14 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Vitali",
"David",
""
],
[
"Tombesi",
"Paolo",
""
],
[
"Milburn",
"Gerard J.",
""
]
] |
quant-ph/9803046 | David Marcus Appleby | D. M. Appleby | The Concept of Experimental Accuracy and Simultaneous Measurements of
Position and Momentum | 15 pages. 0 figures. To be published in International Journal of
Theoretical Physics | Int.J.Theor.Phys. 37 (1998) 1491-1510 | null | QMW-PH-11 | quant-ph | null | The concept of experimental accuracy is investigated in the context of the
unbiased joint measurement processes defined by Arthurs and Kelly. A
distinction is made between the errors of retrodiction and prediction. Four
error-disturbance relationships are derived, analogous to the single
error-disturbance relationship derived by Braginsky and Khalili in the context
of single measurements of position only. A retrodictive and a predictive
error-error relationship are also derived. The connection between these
relationships and the extended Uncertainty Principle of Arthurs and Kelly is
discussed. The similarities and differences between the quantum mechanical and
classical concepts of experimental accuracy are explored. It is argued that
these relationships provide grounds for questioning Uffink's conclusion, that
the concept of a simultaneous measurement of non-commuting observables is not
fruitful.
| [
{
"version": "v1",
"created": "Tue, 17 Mar 1998 18:46:23 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Appleby",
"D. M.",
""
]
] |
quant-ph/9803047 | David Marcus Appleby | D. M. Appleby | Maximal Accuracy and Minimal Disturbance in the Arthurs-Kelly
Simultaneous Measurement Process | 12 pages, 0 figures. AMS-Latex. Earlier version replaced with final
published version | J.Phys.A31:6419-6436,1998 | 10.1088/0305-4470/31/30/009 | QMW-PH-12 | quant-ph | null | The accuracy of the Arthurs-Kelly model of a simultaneous measurement of
position and momentum is analysed using concepts developed by Braginsky and
Khalili in the context of measurements of a single quantum observable. A
distinction is made between the errors of retrodiction and prediction. It is
shown that the distribution of measured values coincides with the initial state
Husimi function when the retrodictive accuracy is maximised, and that it is
related to the final state anti-Husimi function (the P representation of
quantum optics) when the predictive accuracy is maximised. The disturbance of
the system by the measurement is also discussed. A class of minimally
disturbing measurements is characterised. It is shown that the distribution of
measured values then coincides with one of the smoothed Wigner functions
described by Cartwright.
| [
{
"version": "v1",
"created": "Tue, 17 Mar 1998 20:20:07 GMT"
},
{
"version": "v2",
"created": "Thu, 17 Sep 1998 23:31:22 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Appleby",
"D. M.",
""
]
] |
quant-ph/9803048 | N. V. K. Rao | B.G. Sidharth (B.M. Birla Science Centre) | Quantum Mechanical Black Holes: Issues and Ramifications | LaTeX, 11 pages, 30 Kb. To be published in Proc.Int.Symp. "Frontiers
of Fundamental Physics", Universities Press, India | null | null | BSC-CAMCS-97-12-01 | quant-ph | null | The recent model of Quantum Mechanical Black Holes is discussed and its
implications for cosmology, particle structure, low dimensionality and other
issues are examined.
| [
{
"version": "v1",
"created": "Wed, 18 Mar 1998 07:26:01 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sidharth",
"B. G.",
"",
"B.M. Birla Science Centre"
]
] |
quant-ph/9803049 | Carlos Aragao de Carvalho | C. A. A. de Carvalho, R. M. Cavalcanti | Tunneling catastrophes of the partition function | 5 figures, revtex file | Braz.J.Phys. 27 (1997) 373-378 | null | null | quant-ph | null | We use path-integrals to derive a general expression for the semiclassical
approximation to the partition function of a one-dimensional quantum-mechanical
system. Our expression depends solely on ordinary integrals which involve the
potential. For high temperatures, the semiclassical expression is dominated by
single closed paths. As we lower the temperature, new closed paths may appear,
including tunneling paths. The transition from single to multiple-path regime
corresponds to well-defined catastrophes. Tunneling sets in whenever they
occur. Our formula fully accounts for this feature.
| [
{
"version": "v1",
"created": "Wed, 18 Mar 1998 12:55:51 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"de Carvalho",
"C. A. A.",
""
],
[
"Cavalcanti",
"R. M.",
""
]
] |
quant-ph/9803050 | Carlos Aragao de Carvalho | C. A. A. de Carvalho, R. M. Cavalcanti | Semiclassical Statistical Mechanics | Invited talk at the La Plata meeting on `Trends in Theoretical
Physics', La Plata, April, 1997; 14 pages + 5 ps figures. Some cosmetical
modifications, and addition of some references which were missing in the
previous version | AIP Conference Proceedings 419, pp 94-104 (1997) | 10.1063/1.54706 | null | quant-ph | null | We use a semiclassical approximation to derive the partition function for an
arbitrary potential in one-dimensional Quantum Statistical Mechanics, which we
view as an example of finite temperature scalar Field Theory at a point. We
rely on Catastrophe Theory to analyze the pattern of extrema of the
corresponding path-integral. We exhibit the propagator in the background of the
different extrema and use it to compute the fluctuation determinant and to
develop a (nonperturbative) semiclassical expansion which allows for the
calculation of correlation functions. We discuss the examples of the single and
double-well quartic anharmonic oscillators, and the implications of our results
for higher dimensions.
| [
{
"version": "v1",
"created": "Wed, 18 Mar 1998 13:10:48 GMT"
},
{
"version": "v2",
"created": "Wed, 3 Jun 1998 22:10:05 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"de Carvalho",
"C. A. A.",
""
],
[
"Cavalcanti",
"R. M.",
""
]
] |
quant-ph/9803051 | David Marcus Appleby | D. M. Appleby | The Error Principle | AMS-Latex, 13 pages, 0 figures. Some additional discussion and
references. Proofs and results are unchanged | Int.J.Theor.Phys. 37 (1998) 2557-2572 | null | QMW-PH-98-13 | quant-ph | null | The problem of characterising the accuracy of, and disturbance caused by a
joint measurement of position and momentum is investigated. In a previous paper
the problem was discussed in the context of the unbiased measurements
considered by Arthurs and Kelly. It is now shown, that suitably modified
versions of these results hold for a much larger class of simultaneous
measurements. The approach is a development of that adopted by Braginsky and
Khalili in the case of a single measurement of position only. A distinction is
made between the errors of retrodiction and the errors of prediction. Two
error-error relationships and four error-disturbance relationships are derived,
supplementing the Uncertainty Principle usually so-called. In the general case
it is necessary to take into account the range of the measuring apparatus. Both
the ideal case, of an instrument having infinite range, and the case of a real
instrument, for which the range is finite, are discussed.
| [
{
"version": "v1",
"created": "Wed, 18 Mar 1998 16:24:26 GMT"
},
{
"version": "v2",
"created": "Sun, 19 Apr 1998 17:35:00 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Appleby",
"D. M.",
""
]
] |
quant-ph/9803052 | Claus Kiefer | Claus Kiefer and Erich Joos | Decoherence: Concepts and Examples | 24 pages, LATEX, 9 figures, needs macro lamuphys.sty, to appear in
the Proceedings of the 10th Born Symposium | null | 10.1007/BFb0105342 | Freiburg THEP-98/4 | quant-ph cond-mat gr-qc hep-th | null | We give a pedagogical introduction to the process of decoherence - the
irreversible emergence of classical properties through interaction with the
environment. After discussing the general concepts, we present the following
examples: Localisation of objects, quantum Zeno effect, classicality of fields
and charges in QED, and decoherence in gravity theory. We finally emphasise the
important interpretational features of decoherence.
| [
{
"version": "v1",
"created": "Thu, 19 Mar 1998 14:21:14 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Kiefer",
"Claus",
""
],
[
"Joos",
"Erich",
""
]
] |
quant-ph/9803053 | David Marcus Appleby | D. M. Appleby | Optimal Joint Measurements of Position and Momentum | AMS-Latex, 15 pages, 0 figures. Some additional discussion and
references. Arguments and results are unchanged | Int.J.Theor.Phys. 38 (1999) 807-825 | null | QMW-PH-98-14 | quant-ph | null | The distribution of measured values for maximally accurate, unbiased
simultaneous measurements of position and momentum is investigated. It is
shown, that if the measurement is retrodictively optimal, then the distribution
of results is given by the initial state Husimi function (or Q-representation).
If the measurement is predictively optimal, then the distribution of results is
related to the final state anti-Husimi function (or P-representation). The
significance of this universal property for the interpretation of the Husimi
function is discussed.
| [
{
"version": "v1",
"created": "Fri, 20 Mar 1998 01:26:06 GMT"
},
{
"version": "v2",
"created": "Sun, 19 Apr 1998 17:47:44 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Appleby",
"D. M.",
""
]
] |
quant-ph/9803054 | Trevor Marshall | Trevor W. Marshal (Dept. of Maths., Manchester Univ., Manchester M13
9PL, U.K) | Parametric up conversion of the vacuum | See also http://www.keyinnov.demon.co.uk and
http://xxx.lanl.gov/abs/quant-ph/9712050 | null | null | MUM-98-04 | quant-ph | null | The theory of parametric down conversion of the vacuum, based on a real
zeropoint, or "vacuum" electromagnetic field, has been treated in earlier
articles. The same theory predicts a hitherto unsuspected phenomenon -
parametric up conversion of the vacuum. This article describes how the
phenomenon may be demonstrated experimentally.
| [
{
"version": "v1",
"created": "Fri, 20 Mar 1998 13:30:28 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Marshal",
"Trevor W.",
"",
"Dept. of Maths., Manchester Univ., Manchester M13\n 9PL, U.K"
]
] |
quant-ph/9803055 | Chris Isham | C.J. Isham and J. Butterfield | A topos perspective on the Kochen-Specker theorem: I. Quantum States as
Generalized Valuations | Clarification of situation for situation for operators with
continuous spectra | null | null | Imperial/TP/97-98/28 | quant-ph gr-qc | null | The Kochen-Specker theorem asserts the impossibility of assigning values to
quantum quantities in a way that preserves functional relations between them.
We construct a new type of valuation which is defined on all operators, and
which respects an appropriate version of the functional composition principle.
The truth-values assigned to propositions are (i) contextual; and (ii)
multi-valued, where the space of contexts and the multi-valued logic for each
context come naturally from the topos theory of presheaves.
The first step in our theory is to demonstrate that the Kochen-Specker
theorem is equivalent to the statement that a certain presheaf defined on the
category of self-adjoint operators has no global elements. We then show how the
use of ideas drawn from the theory of presheaves leads to the definition of a
generalized valuation in quantum theory whose values are sieves of operators.
In particular, we show how each quantum state leads to such a generalized
valuation.
| [
{
"version": "v1",
"created": "Fri, 20 Mar 1998 14:26:52 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Mar 1998 08:43:43 GMT"
},
{
"version": "v3",
"created": "Mon, 31 Aug 1998 15:12:29 GMT"
},
{
"version": "v4",
"created": "Tue, 13 Oct 1998 12:49:13 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Isham",
"C. J.",
""
],
[
"Butterfield",
"J.",
""
]
] |
quant-ph/9803056 | Hans Juergen Briegel | H.-J. Briegel, W. D\"ur, J. I. Cirac, and P. Zoller | Quantum repeaters for communication | 8 pages, 3 figures, 1 table | null | null | HJB-98-1 | quant-ph | null | In quantum communication via noisy channels, the error probability scales
exponentially with the length of the channel. We present a scheme of a quantum
repeater that overcomes this limitation. The central idea is to connect a
string of (imperfect) entangled pairs of particles by using a novel nested
purification protocol, thereby creating a single distant pair of high fidelity.
The scheme tolerates general errors on the percent level.
| [
{
"version": "v1",
"created": "Fri, 20 Mar 1998 14:41:10 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Briegel",
"H. -J.",
""
],
[
"Dür",
"W.",
""
],
[
"Cirac",
"J. I.",
""
],
[
"Zoller",
"P.",
""
]
] |
quant-ph/9803057 | Lorenza Viola | Lorenza Viola, Seth Lloyd (Dept. of Mechanical Engineering, MIT) | Dynamical suppression of decoherence in two-state quantum systems | 15 pages, RevTeX style, 3 figures. Submitted to Phys. Rev. A | null | 10.1103/PhysRevA.58.2733 | null | quant-ph | null | The dynamics of a decohering two-level system driven by a suitable control
Hamiltonian is studied. The control procedure is implemented as a sequence of
radiofrequency pulses that repetitively flip the state of the system, a
technique that can be termed quantum "bang-bang" control after its classical
analog. Decoherence introduced by the system's interaction with a quantum
environment is shown to be washed out completely in the limit of continuous
flipping and greatly suppressed provided the interval between the pulses is
made comparable to the correlation time of the environment. The model suggests
a strategy to fight against decoherence that complements existing quantum
error-correction techniques.
| [
{
"version": "v1",
"created": "Fri, 20 Mar 1998 23:07:44 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Viola",
"Lorenza",
"",
"Dept. of Mechanical Engineering, MIT"
],
[
"Lloyd",
"Seth",
"",
"Dept. of Mechanical Engineering, MIT"
]
] |
quant-ph/9803058 | Nicolas Cerf | Nicolas J. Cerf (Caltech) | Quantum cloning and the capacity of the Pauli channel | 5 pages RevTeX, 3 Postscript figures | Phys.Rev.Lett. 84 (2000) 4497 | 10.1103/PhysRevLett.84.4497 | KRL MAP-220 | quant-ph | null | A family of quantum cloning machines is introduced that produce two
approximate copies from a single quantum bit, while the overall input-to-output
operation for each copy is a Pauli channel. A no-cloning inequality is derived,
describing the balance between the quality of the two copies. This also
provides an upper bound on the quantum capacity of the Pauli channel with
probabilities $p_x$, $p_y$ and $p_z$. The capacity is shown to be vanishing if
$(\sqrt{p_x},\sqrt{p_y},\sqrt{p_z})$ lies outside an ellipsoid whose pole
coincides with the depolarizing channel that underlies the universal cloning
machine.
| [
{
"version": "v1",
"created": "Sun, 22 Mar 1998 04:51:03 GMT"
},
{
"version": "v2",
"created": "Mon, 30 Mar 1998 22:50:51 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Cerf",
"Nicolas J.",
"",
"Caltech"
]
] |
quant-ph/9803059 | Revzen Michael | M. Revzen and A. Mann | Casimir Effect - The Classical Limit | 11 pages, latex, 1 postscript figure (the postscript corrected) | null | null | null | quant-ph | null | The temperature dependence of the Casimir effect for the radiation field
confined between two conducting plates is analysed. The Casimir energy is shown
to decline exponentially with temperature while the Casimir entropy which is
defined in the text is shown to approach a limit which depends only on the
geometry of the constraining plates. The results are discussed in terms of the
relation between the Bose distribution function and the equipartition theorem -
a relation based on a study by Einstein and Stern circa 1913.
| [
{
"version": "v1",
"created": "Sun, 22 Mar 1998 08:55:41 GMT"
},
{
"version": "v2",
"created": "Sun, 29 Mar 1998 14:27:37 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Revzen",
"M.",
""
],
[
"Mann",
"A.",
""
]
] |
quant-ph/9803060 | Andrew G. White | Andrew G. White (1), Jay R. Mitchell (1), Olaf Nairz (2) and Paul G.
Kwiat (1) ((1) Los Alamos National Laboratory, (2) Universitaet Innsbruck) | "Interaction-Free" Imaging | 10 pages, 6 encapsulated Postscript figure files, accepted for
publication in Physical Review A | Physical Review A 58, 605-608 (1998) | 10.1103/PhysRevA.58.605 | null | quant-ph physics.ins-det physics.optics | null | Using the complementary wave- and particle-like natures of photons, it is
possible to make ``interaction-free'' measurements where the presence of an
object can be determined with no photons being absorbed. We investigated
several ``interaction-free'' imaging systems, i.e. systems that allow optical
imaging of photosensitive objects with less than the classically expected
amount of light being absorbed or scattered by the object. With the most
promising system, we obtained high-resolution (10 \mu m), one-dimensional
profiles of a variety of objects (human hair, glass and metal wires, cloth
fibers), by raster scanning each object through the system. We discuss possible
applications and the present and future limits for interaction-free imaging.
| [
{
"version": "v1",
"created": "Mon, 23 Mar 1998 01:57:52 GMT"
},
{
"version": "v2",
"created": "Sun, 26 Apr 1998 21:19:36 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"White",
"Andrew G.",
"",
"Los Alamos National Laboratory"
],
[
"Mitchell",
"Jay R.",
"",
"Los Alamos National Laboratory"
],
[
"Nairz",
"Olaf",
"",
"Universitaet Innsbruck"
],
[
"Kwiat",
"Paul G.",
"",
"Los Alamos National Laboratory"
]
] |
quant-ph/9803061 | Christian Wiele | C. Wiele, F. Haake, C. Rocke, A. Wixforth | Photon trains and lasing : The periodically pumped quantum dot | RevTex, 5 pages, 1 figure | null | 10.1103/PhysRevA.58.R2680 | WIELE-98-01 | quant-ph cond-mat.mes-hall | null | We propose to pump semiconductor quantum dots with surface acoustic waves
which deliver an alternating periodic sequence of electrons and holes. In
combination with a good optical cavity such regular pumping could entail
anti-bunching and sub-Poissonian photon statistics. In the bad-cavity limit a
train of equally spaced photons would arise.
| [
{
"version": "v1",
"created": "Mon, 23 Mar 1998 12:51:39 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Wiele",
"C.",
""
],
[
"Haake",
"F.",
""
],
[
"Rocke",
"C.",
""
],
[
"Wixforth",
"A.",
""
]
] |
quant-ph/9803062 | Walter T. Strunz | L. Diosi, N. Gisin, and W. T. Strunz | Non-Markovian Quantum State Diffusion | 22 pages, 6 figures | null | 10.1103/PhysRevA.58.1699 | UGHE-TP-9803 | quant-ph | null | We present a nonlinear stochastic Schroedinger equation for pure states
describing non-Markovian diffusion of quantum trajectories. It provides an
unravelling of the evolution of a quantum system coupled to a finite or
infinite number of harmonic oscillators, without any approximation. Its power
is illustrated by several examples, including measurement-like situations,
dissipation, and quantum Brownian motion. In some examples, we treat the
environment phenomenologically as an infinite reservoir with fluctuations of
arbitrary correlation. In other examples the environment consists of a finite
number of oscillators. In these quasi-periodic cases we see the reversible
decay of a `Schroedinger cat' state. Finally, our description of open systems
is compatible with different positions of the `Heisenberg cut' between system
and environment.
| [
{
"version": "v1",
"created": "Mon, 23 Mar 1998 15:27:09 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Diosi",
"L.",
""
],
[
"Gisin",
"N.",
""
],
[
"Strunz",
"W. T.",
""
]
] |
quant-ph/9803063 | Paolo Maraner | P. Maraner | A Dynamical Mechanism for the Selection of Physical States in `Geometric
Quantization Schemes' | 6 pages | Rept.Math.Phys. 40 (1997) 265-271 | 10.1016/S0034-4877(97)85923-X | null | quant-ph | null | Geometric quantization procedures go usually through an extension of the
original theory (pre-quantization) and a subsequent reduction (selection of the
physical states). In this context we describe a full geometrical mechanism
which provides dynamically the desired reduction.
| [
{
"version": "v1",
"created": "Mon, 23 Mar 1998 18:12:36 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Maraner",
"P.",
""
]
] |
quant-ph/9803064 | Yuri I. Ozhigov | Yuri Ozhigov | Quantum Computers Speed Up Classical with Probability Zero | 11 pages, LATEX | Chaos Solitons Fractals 10 (1999) 1707-1714 | null | null | quant-ph | null | Let $f$ denote length preserving function on words. A classical algorithm can
be considered as $T$ iterated applications of black box representing $f$,
beginning with input word $x$ of length $n$.
It is proved that if $T=O(2^{n/(7+e)}), e >0$, and $f$ is chosen randomly
then with probability 1 every quantum computer requires not less than $T$
evaluations of $f$ to obtain the result of classical computation. It means that
the set of classical algorithms admitting quantum speeding up has probability
measure zero.
The second result is that for arbitrary classical time complexity $T$ and $f$
chosen randomly with probability 1 every quantum simulation of classical
computation requires at least $\Omega (\sqrt {T})$ evaluations of $f$.
| [
{
"version": "v1",
"created": "Tue, 24 Mar 1998 15:26:22 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ozhigov",
"Yuri",
""
]
] |
quant-ph/9803065 | Giacomo Mauro D'Ariano | Giacomo M. D'Ariano, Michael Vasilyev, and Prem Kumar (Department of
Electrical and Computer Engineering, Northwestern University, Evanston, IL,
USA) | Self-homodyne tomography of a twin-beam state | 13 pages (two-column ReVTeX) including 21 postscript figures; to
appear on Phys. Rev. A | Phys.Rev. A58 (1998) 636 | 10.1103/PhysRevA.58.636 | null | quant-ph | null | A self-homodyne detection scheme is proposed to perform two-mode tomography
on a twin-beam state at the output of a nondegenerate optical parametric
amplifier. This scheme has been devised to improve the matching between the
local oscillator and the signal modes, which is the main limitation to the
overall quantum efficiency in conventional homodyning. The feasibility of the
measurement is analyzed on the basis of Monte-Carlo simulations, studying the
effect of non-unit quantum efficiency on detection of the correlation and the
total photon-number oscillations of the twin-beam state.
| [
{
"version": "v1",
"created": "Tue, 24 Mar 1998 19:56:28 GMT"
},
{
"version": "v2",
"created": "Thu, 2 Apr 1998 12:19:09 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"D'Ariano",
"Giacomo M.",
"",
"Department of\n Electrical and Computer Engineering, Northwestern University, Evanston, IL,\n USA"
],
[
"Vasilyev",
"Michael",
"",
"Department of\n Electrical and Computer Engineering, Northwestern University, Evanston, IL,\n USA"
],
[
"Kumar",
"Prem",
"",
"Department of\n Electrical and Computer Engineering, Northwestern University, Evanston, IL,\n USA"
]
] |
quant-ph/9803066 | Jose I. Latorre | J.I. Latorre, P. Pascual and R. Tarrach | Minimal optimal generalized quantum measurements | 9 pages, Latex | Phys.Rev.Lett. 81 (1998) 1351-1354 | 10.1103/PhysRevLett.81.1351 | UB-ECM-1 | quant-ph hep-th | null | Optimal and finite positive operator valued measurements on a finite number
$N$ of identically prepared systems have been presented recently. With physical
realization in mind we propose here optimal and minimal generalized quantum
measurements for two-level systems.
We explicitly construct them up to N=7 and verify that they are minimal up to
N=5. We finally propose an expression which gives the size of the minimal
optimal measurements for arbitrary $N$.
| [
{
"version": "v1",
"created": "Wed, 25 Mar 1998 10:46:07 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Latorre",
"J. I.",
""
],
[
"Pascual",
"P.",
""
],
[
"Tarrach",
"R.",
""
]
] |
quant-ph/9803067 | Abdullah | A. Vercin | Metaplectic Covariance of the Weyl-Wigner-Groenewold-Moyal Quantization
and Beyond | 20 pages,no figures,to appear in Ann. Phys.(N.Y) | Annals Phys. 266 (1998) 503-523 | 10.1006/aphy.1998.5805 | null | quant-ph | null | The metaplectic covariance for all forms of the Weyl-Wigner-Groenewold-Moyal
quantization is established with different realizations of the inhomogeneous
symplectic algebra. Beyond that, in its most general form $W_{\infty}$
-covariance of this quantization scheme is investigated, and explicit
expressions for the quantum-deformed Hamiltonian vector fields are presented.
In a general basis the structure constants of the $W_{\infty}$-algebra are
obtained and its subalgebras are analyzed.
| [
{
"version": "v1",
"created": "Wed, 25 Mar 1998 11:38:58 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Vercin",
"A.",
""
]
] |
quant-ph/9803068 | Fabrizio Illuminati | Salvatore De Martino, Silvio De Siena, and F. Illuminati | Semiclassical Aspects of Quantum Mechanics by Classical Fluctuations | Plain LaTeX, 11 pages, no figures | Mod.Phys.Lett. B12 (1998) 291 | 10.1142/S0217984998000378 | null | quant-ph | null | Building on a model recently proposed by F. Calogero, we postulate the
existence of a coherent, long--range universal tremor affecting any stable and
confined classical dynamical system. Deriving the characteristic fluctuative
unit of action for each classical interaction, we obtain in all cases its
numerical coincidence with the Planck action constant. We therefore suggest
that quantum corrections to classical dynamics can be simulated by suitable
classical stochastic fluctuations.
| [
{
"version": "v1",
"created": "Wed, 25 Mar 1998 14:17:19 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"De Martino",
"Salvatore",
""
],
[
"De Siena",
"Silvio",
""
],
[
"Illuminati",
"F.",
""
]
] |
quant-ph/9803069 | Dr. Luca Salasnich, . D. | Luca Salasnich | Classical and Quantum Perturbation Theory for two Non--Resonant
Oscillators with Quartic Interaction | 11 pages, Latex, no figures, to be published in Meccanica | null | null | null | quant-ph | null | We study the classical and quantum perturbation theory for two non--resonant
oscillators coupled by a nonlinear quartic interaction. In particular we
analyze the question of quantum corrections to the torus quantization of the
classical perturbation theory (semiclassical mechanics). We obtain up to the
second order of perturbation theory an explicit analytical formula for the
quantum energy levels, which is the semiclassical one plus quantum corrections.
We compare the "exact" quantum levels obtained numerically to the semiclassical
levels studying also the effects of quantum corrections.
| [
{
"version": "v1",
"created": "Wed, 25 Mar 1998 16:30:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Salasnich",
"Luca",
""
]
] |
quant-ph/9803070 | Ramin Golestanian | Faez Miri and Ramin Golestanian | Motion-Induced Radiation from a Dynamically Deforming Mirror | 4 pages, 2 eps figues included, final version as appeared in PRA | Phys. Rev. A 59, 2291 (1999) | 10.1103/PhysRevA.59.2291 | null | quant-ph cond-mat hep-th physics.atom-ph | null | A path integral formulation is developed to study the spectrum of radiation
from a perfectly reflecting (conducting) surface. It allows us to study
arbitrary deformations in space and time. The spectrum is calculated to second
order in the height function. For a harmonic traveling wave on the surface, we
find many different regimes in which the radiation is restricted to certain
directions. It is shown that high frequency photons are emitted in a beam with
relatively low angular dispersion whose direction can be controlled by the
mechanical deformations of the plate.
| [
{
"version": "v1",
"created": "Wed, 25 Mar 1998 19:04:45 GMT"
},
{
"version": "v2",
"created": "Wed, 19 May 1999 20:06:22 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Miri",
"Faez",
""
],
[
"Golestanian",
"Ramin",
""
]
] |
quant-ph/9803071 | Anupam Garg | Anupam Garg | Vibrational Decoherence in Ion-Trap Quantum Computers | 13 pages, 2 figures | Proc.SPIE Int.Soc.Opt.Eng. 3385 (1998) 35 | null | ag-qc-2 | quant-ph | null | Decoherence is studied in an attractive proposal for an actual implementation
of a quantum computer based on trapped ions. Emphasis is placed on the
decoherence arising from the vibrational motion of the ions, which is compared
with that due to spontaneous emission from excited states of the ions. The
calculation is made tractable by exploiting the vast difference in time scales
between the vibrational excitations and the intra-ionic electronic excitations.
Since the latter are several orders of magnitude faster, an adiabatic
approximation is used to integrate them out and find the inclusive probability
P(t) for the elec- tronic state of the ions to evolve as it would in the
absence of vibrational coupling, and the ions to evolve into any state
whatsoever. The decoherence time is found at zero temperature and for any
number of ions N in the computer. Comparison is made with the spontaneous
emission decoherence, and the implications for how trap voltages and other
parameters should be scaled with N are discussed.
| [
{
"version": "v1",
"created": "Wed, 25 Mar 1998 19:35:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Garg",
"Anupam",
""
]
] |
quant-ph/9803072 | Richard Jozsa | Artur Ekert and Richard Jozsa | Quantum Algorithms: Entanglement Enhanced Information Processing | 17 pages latex, no figures. To appear in Phil. Trans. Roy. Soc.
(Lond.) 1998, Proceedings of Royal Society Discussion Meeting ``Quantum
Computation: Theory and Experiment'', held in November 1997 | null | 10.1098/rsta.1998.0248 | null | quant-ph | null | We discuss the fundamental role of entanglement as the essential nonclassical
feature providing the computational speed-up in the known quantum algorithms.
We review the construction of the Fourier transform on an Abelian group and the
principles underlying the fast Fourier transform algorithm. We describe the
implementation of the FFT algorithm for the group of integers modulo 2^n in the
quantum context, showing how the group-theoretic formalism leads to the
standard quantum network and identifying the property of entanglement that
gives rise to the exponential speedup (compared to the classical FFT). Finally
we outline the use of the Fourier transform in extracting periodicities, which
underlies its utility in the known quantum algorithms.
| [
{
"version": "v1",
"created": "Thu, 26 Mar 1998 09:15:12 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Ekert",
"Artur",
""
],
[
"Jozsa",
"Richard",
""
]
] |
quant-ph/9803073 | Dr A. K. Kapoor | S. Chaturvedi, A.K. Kapoor and V. Srinivasan | A new orthogonalization procedure with an extremal property | 7 pages, latex, no figures, To appear in J. Phys A | J.Phys. A31 (1998) L367-L370 | 10.1088/0305-4470/31/19/002 | null | quant-ph | null | Various methods of constructing an orthonomal set out of a given set of
linearly independent vectors are discussed. Particular attention is paid to the
Gram-Schmidt and the Schweinler-Wigner orthogonalization procedures. A new
orthogonalization procedure which, like the Schweinler- Wigner procedure, is
democratic and is endowed with an extremal property is suggested.
| [
{
"version": "v1",
"created": "Thu, 26 Mar 1998 09:33:39 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Chaturvedi",
"S.",
""
],
[
"Kapoor",
"A. K.",
""
],
[
"Srinivasan",
"V.",
""
]
] |
quant-ph/9803074 | Dr. Luca Salasnich, . D. | Luca Salasnich | Statistical Mechanics of a Trapped Bose-Einstein Condensate | 4 pages, Latex, no figures, presented to SIMAI98, Giardini Naxos,
Messina, 1998 | null | null | null | quant-ph | null | Bose-Einstein condensation (BEC) in a gas has now been achieved. Alkali atoms
($^{87}Rb$, $^{23}Na$ and $^{7}Li$) have been cooled to the point of
condensation (temperature of 100 nK) using laser cooling and trapping, followed
by magnetic trapping and evaporative cooling. This important experimental
result has also renewed the interest on theoretical studies of BEC. In this
contribution we discuss the statistical mechanics of the trapped BEC at zero
temperature. In particular, we study the stability of the condensate by using a
variational method with local and non-local interaction between the particles.
| [
{
"version": "v1",
"created": "Thu, 26 Mar 1998 11:06:52 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Salasnich",
"Luca",
""
]
] |
quant-ph/9803075 | Adonai S. Sant'Anna | Adonai S. Sant'Anna (Federal University at Parana) | Hidden variables, quasi-sets, and elementary particles | LaTeX, 14 pages, no figures, one table | null | null | null | quant-ph | null | We have recently showed that it is possible to deal with collections of
indistinguishable elementary particles (in the context of quantum mechanics) in
a set-theoretical framework by using hidden variables, in a sense. In the
present paper we use such a formalism as a model for quasi-set theory.
Quasi-set theory, based on Zermelo-Fraenkel set theory, was developed for
dealing with collections of indistinguishable but, in a sense, not identical
objects.
| [
{
"version": "v1",
"created": "Fri, 27 Mar 1998 01:09:21 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sant'Anna",
"Adonai S.",
"",
"Federal University at Parana"
]
] |
quant-ph/9803076 | Adonai S. Sant'Anna | Decio Krause (Federal University at Parana), Adonai S. Sant'Anna
(Federal University at Parana), and Analice G. Volkov (Federal University at
Parana) | Quasi-set theory for bosons and fermions: quantum distributions | 20 pages, no figures, one table | Found.Phys.Lett. 12 (1999) 51-66 | 10.1023/A:1021678721611 | null | quant-ph | null | Quasi-set theory provides a mathematical background for dealing with
collections of indistinguishable elementary particles. In this paper, we show
how to obtain the quantum statistics into the scope of quasi-set theory and
discuss the Helium atom, which represents the simplest example where
indistinguishability plays an important role. A brief discussion about
indistinguishability and interference is also presented as well as other
related lines of work. One of the advantages of our approach is that one of the
most basic principles of quantum theory, namely, the Indistinguishability
Postulate, does not need to be assumed even implicetely in the axiomatic basis
of quantum mechanics.
| [
{
"version": "v1",
"created": "Thu, 26 Mar 1998 17:10:40 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Krause",
"Decio",
"",
"Federal University at Parana"
],
[
"Sant'Anna",
"Adonai S.",
"",
"Federal University at Parana"
],
[
"Volkov",
"Analice G.",
"",
"Federal University at\n Parana"
]
] |
quant-ph/9803077 | M. Dakna | M. Dakna, L. Knoll, and D.-G. Welsch | Quantum state engineering using conditional measurement on a beam
splitter | 8 figures using a4.sty | null | null | null | quant-ph | null | State preparation via conditional output measurement on a beam splitter is
studied, assuming the signal mode is mixed with a mode prepared in a Fock state
and photon numbers are measured in one of the output channels. It is shown that
the mode in the other output channel is prepared in either a photon-subtracted
or a photon-added Jacobi polynomial state, depending upon the difference
between the number of photons in the input Fock state and the number of photons
in the output Fock state onto which it is projected. The properties of the
conditional output states are studied for coherent and squeezed input states,
and the probabilities of generating the states are calculated. Relations to
other states, such as near-photon-number states and squeezed-state-excitations,
are given and proposals are made for generating them by combining the scheme
with others. Finally, effects of realistic photocounting and Fock-state
preparation are discussed.
| [
{
"version": "v1",
"created": "Thu, 26 Mar 1998 17:22:24 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Dakna",
"M.",
""
],
[
"Knoll",
"L.",
""
],
[
"Welsch",
"D. -G.",
""
]
] |
quant-ph/9803078 | Piotr Rozmej | R. Arvieu (ISN, Grenoble, France) and P. Rozmej (University MCS,
Lublin, Poland and GSI, Darmstadt, Germany) | Pictures of quantum nuclear rotation beyond the correspondence principle | Revised and extended version, to be publish in EPJdirect, Latex2e,
with EPJ style file included, 13 pages, 8 figures (in 7 pages) | Eur.Phys.J. A1 (1999) 1-18 | 10.1007/s100500050297 | null | quant-ph nucl-th | null | We analyze the time evolution of simple nuclear rotational wave packets (WP)
called circular, linear or elliptic, depending on squeezing parameter $\eta$,
assuming that $E=\hbar\omega_0 I(I+1)$. The scenario of fractional revivals
found by Averbukh and Perelman is adapted to symmetric WP and compared to that
which holds for asymmetric WP. In both cases various shapes are identified
under these lines in particular many cases of cloning. 'Mutants' WP are found
most often. Finally the time evolution of a WP formed by Coulomb excitation on
$^{238}$U and calculated by semiclassical theory is also presented.
| [
{
"version": "v1",
"created": "Fri, 27 Mar 1998 14:26:50 GMT"
},
{
"version": "v2",
"created": "Sat, 27 Mar 1999 14:04:40 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Arvieu",
"R.",
"",
"ISN, Grenoble, France"
],
[
"Rozmej",
"P.",
"",
"University MCS,\n Lublin, Poland and GSI, Darmstadt, Germany"
]
] |
quant-ph/9803079 | Walter T. Strunz | Walter T Strunz, Lajos Diosi, and Nicolas Gisin | Open system dynamics with non-Markovian quantum trajectories | 4 pages RevTeX, 3 figures | Phys.Rev.Lett. 82 (1999) 1801-1805 | 10.1103/PhysRevLett.82.1801 | UGHE-TP-9804 | quant-ph | null | A non-Markovian stochastic Schroedinger equation for a quantum system coupled
to an environment of harmonic oscillators is presented. Its solutions, when
averaged over the noise, reproduce the standard reduced density operator
without any approximation. We illustrate the power of this approach with
several examples, including exponentially decaying bath correlations and
extreme non-Markovian cases, where the `environment' consists of only a single
oscillator. The latter case shows the decay and revival of a `Schroedinger cat'
state. For strong coupling to a dissipative environment with memory, the
asymptotic state can be reached in a finite time. Our description of open
systems is compatible with different positions of the `Heisenberg cut' between
system and environment.
| [
{
"version": "v1",
"created": "Fri, 27 Mar 1998 15:29:32 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Strunz",
"Walter T",
""
],
[
"Diosi",
"Lajos",
""
],
[
"Gisin",
"Nicolas",
""
]
] |
quant-ph/9803080 | Michal Horodecki | Michal Horodecki, Ryszard Horodecki and Pawel Horodecki | Optimal compression of quantum information for one-qubit source at
incomplete data: a new aspect of Jaynes principle | RevTeX, 4 pages, a simpler version of the proof for compression at
two-observable data has been provided, some minor changes has been made | Acta Phys.Slov. 48 (1998) 133-140 | null | null | quant-ph | null | We consider the problem of optimal processing of quantum information at
incomplete experimental data characterizing the quantum source. In particular,
we then prove that for one-qubit quantum source the Jaynes principle offers a
simple scheme for optimal compression of quantum information. According to the
scheme one should process as if the density matrix of the source were actually
equal to the matrix of the Jaynes state.
| [
{
"version": "v1",
"created": "Fri, 27 Mar 1998 16:44:42 GMT"
},
{
"version": "v2",
"created": "Tue, 31 Mar 1998 16:51:35 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Horodecki",
"Michal",
""
],
[
"Horodecki",
"Ryszard",
""
],
[
"Horodecki",
"Pawel",
""
]
] |
quant-ph/9803081 | Simon Brattke | S. Brattke, U. Kallmann and W.-D. Hartmann | Coherent Dark States of Rubidium 87 in a Buffer Gas using Pulsed Laser
Light | 3 pages, 5 figures, 1 misprint corrected | null | 10.1007/s100530050159 | null | quant-ph | null | The coherent dark resonance between the hyperfine levels F=1, m=0 and F=2,
m=0 of the rubidium ground state has been observed experimentally with the
light of a pulsed mode-locked diode laser operating at the D1 transition
frequency. The resonance occurs whenever the pulse repetition frequency matches
an integer fraction of the rubidium 87 ground state hyperfine splitting of 6.8
GHz. Spectra have been taken by varying the pulse repetition frequency. Using
cells with argon as a buffer gas a linewidth as narrow as 149 Hz was obtained.
The rubidium ground state decoherence cross section 1.1*10^(-18) cm^2 for
collisions with xenon atoms has been measured for the first time with this
method using a pure isotope rubidium vapor cell and xenon as a buffer gas.
| [
{
"version": "v1",
"created": "Fri, 27 Mar 1998 17:28:56 GMT"
},
{
"version": "v2",
"created": "Wed, 8 Apr 1998 15:34:21 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Brattke",
"S.",
""
],
[
"Kallmann",
"U.",
""
],
[
"Hartmann",
"W. -D.",
""
]
] |
quant-ph/9803082 | Dr. A. K. Mitra | A. K. Pati and S. V. Lawande (B.A.R.C, Mumbai) | Geometry of the Hilbert space and the Quantum Zeno Effect | 10 pages, Latex, no figures, submitted to Phys. Rev. A | null | 10.1103/PhysRevA.58.831 | null | quant-ph | null | We show that the quadratic short time behaviour of transition probability is
a natural consequence of the inner product of the Hilbert space of the quantum
system. We prove that Schr\"odinger time evolution between two successive
measurements is not a necessary but only a sufficient condition for predicting
quantum Zeno effect. We provide a relation between the survival probability and
the underlying geometric structure such as the Fubini-Study metric defined on
the projective Hilbert space of the quantum system. This predicts the quantum
Zeno effect even for systems described by non-linear and non-unitary evolution
equations, within the collapse mechanism of the wavefunction during measurement
process. Two examples are studied, one is non-linear Schr\"odinger equation and
other is Gisin's equation and it is shown that one can observe quantum Zeno
effect for systems described by these equations.
| [
{
"version": "v1",
"created": "Sun, 29 Mar 1998 04:55:11 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Pati",
"A. K.",
"",
"B.A.R.C, Mumbai"
],
[
"Lawande",
"S. V.",
"",
"B.A.R.C, Mumbai"
]
] |
quant-ph/9803083 | 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. 0.
Preliminary considerations: Quantum mechanics from a geometric-observer's
viewpoint | 15 standard LaTeX 2e (11pt, A4) pages. The packages AMS-LaTeX and
amsfonts are required | J.Phys.A31:1297-1305,1998 | 10.1088/0305-4470/31/4/017 | null | quant-ph gr-qc hep-th math.DG math.GT | null | We propose a version of the non-relativistic quantum mechanics in which the
pure states of a quantum system are described as sections of a Hilbert
(generally infinitely-dimensional) fibre bundle over the space-time. There
evolution is governed via (a kind of) a parallel transport in this bundle. Some
problems concerning observables are considered. There are derived the equations
of motion for the state sections and observables. We show that up to a constant
the matrix of the coefficients of the evolution operator (transport) coincides
with the matrix of the Hamiltonian of the investigated quantum system.
| [
{
"version": "v1",
"created": "Sun, 29 Mar 1998 07:22:09 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/9803084 | 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: I.
Introduction. The evolution transport | 26 standard (11pt, A4) LaTeX 2e pages. The packages AMS-LaTeX and
amsfonts are required. Revised: new material, references, and comments are
added. Minor style chages. Continuation of quan-ph/9803083. For continuation
of the this series see http://www.inrne.bas.bg/mathmod/bozhome/ | J.Phys.A34:4887-4918,2001 | 10.1088/0305-4470/34/23/308 | null | quant-ph gr-qc hep-th math.DG math.GT | 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.
The present first part of this investigation is devoted to the introduction
of basic concepts on which the fibre bundle approach to quantum mechanics
rests. We show that the evolution of pure quantum-mechanical states can be
described as a suitable linear transport along paths, called evolution
transport, of the state sections in the Hilbert fibre bundle of states of a
considered quantum system.
| [
{
"version": "v1",
"created": "Sun, 29 Mar 1998 07:24:12 GMT"
},
{
"version": "v2",
"created": "Fri, 16 Oct 1998 15:03:49 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/9803085 | Yeranuhy Hakobyan | Ye.M. Hakobyan, G.S. Pogosyan | On Interbasis Expansion for Isotropic Oscillator on Two-Dimensional
Sphere | 9 pages, LaTex | Proc., II International Workshop "Lie Theory and Its Applications
in Physics", (Clausthal, August 1997); eds. H.-D. Doebner, V.K. Dobrev and J.
Hilgert, (World Sci, Singapore, 1998, ISBN 981-02-3539-9) pp. 243-251 | null | Preprint JINR E2-98-82 | quant-ph hep-th math-ph math.MP | null | In this article we analyze the isotropic oscillator system on the
two-dimensional sphere in the spherical systems of coordinates. The expansion
coefficients for transitions between three spherical bases of the oscillator
are calculated. It is shown that these coefficients are expressed through the
Clebsch-Gordan coefficients for SU(2) group analytically continued to real
values of their argument.
| [
{
"version": "v1",
"created": "Mon, 30 Mar 1998 16:12:49 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Jul 1999 21:55:04 GMT"
},
{
"version": "v3",
"created": "Fri, 9 Jul 1999 19:34:01 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Hakobyan",
"Ye. M.",
""
],
[
"Pogosyan",
"G. S.",
""
]
] |
quant-ph/9803086 | Ariel Caticha | Ariel Caticha | Consistency and Linearity in Quantum Theory | null | Phys.Lett. A244 (1998) 13-17 | 10.1016/S0375-9601(98)00289-8 | null | quant-ph cond-mat.stat-mech gr-qc math-ph math.MP | null | Quantum theory is formulated as the uniquely consistent way to manipulate
probability amplitudes. The crucial ingredient is a consistency constraint: if
the amplitude of a quantum process can be computed in two different ways, the
two answers must agree. The constraint is expressed in the form of functional
equations the solution of which leads to the usual sum and product rules for
amplitudes. An immediate consequence is that the Schrodinger equation must be
linear: non-linear variants of quantum mechanics violate the requirement of
consistency.
PACS: 03.65.Bz, 03.65.Ca.
| [
{
"version": "v1",
"created": "Tue, 31 Mar 1998 14:50:13 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Caticha",
"Ariel",
""
]
] |
quant-ph/9803087 | null | J. G. Muga, J. P. Palao and C. R. Leavens | Quantum arrival time measurement and backflow effect | LATEX, 9 pages, 2 postscript figures | Phys.Lett. A253 (1999) 21 | 10.1016/S0375-9601(99)00020-1 | ULL-FIS-980301 | quant-ph | null | The current density for a freely evolving state without negative momentum
components can temporarily be negative. The operational arrival time
distribution, defined by the absorption rate of an ideal detector, is
calculated for a model detector and compared with recently proposed
distributions. Counterintuitive features of the backflow regime are discussed.
| [
{
"version": "v1",
"created": "Tue, 31 Mar 1998 16:21:10 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Muga",
"J. G.",
""
],
[
"Palao",
"J. P.",
""
],
[
"Leavens",
"C. R.",
""
]
] |
quant-ph/9804001 | R. F. Werner | R. F. Werner | Optimal Cloning of Pure States | 12 pages, plain TeX, no figs | null | 10.1103/PhysRevA.58.1827 | TUBS/IMaPh-98-11 | quant-ph | null | We construct the unique optimal quantum device for turning a finite number of
d-level quantum systems in the same unknown pure state \sigma into M systems of
the same kind, in an approximation of the M-fold tensor product of the state
\sigma.
| [
{
"version": "v1",
"created": "Wed, 1 Apr 1998 08:28:01 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Werner",
"R. F.",
""
]
] |
quant-ph/9804002 | Lars M. Johansen | Lars M. Johansen | Nonclassical evolution of a free particle | To appear in proceedings of the 5th International Conference on
Squeezed States and Uncertainty Relations | null | null | null | quant-ph | null | A conditional kinetic energy is defined in terms of the Wigner distribution.
It is shown that this kinetic energy may become negative for negative Wigner
distributions. A free particle wave packet with negative kinetic energy will
spread in a nonclassical manner.
| [
{
"version": "v1",
"created": "Wed, 1 Apr 1998 11:41:11 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Johansen",
"Lars M.",
""
]
] |
quant-ph/9804003 | Comman area for Thpd | Arun K. Pati (B.A.R.C., Mumbai, India) | Fluctuation, time-correlation function and geometric Phase | Latex, 12 pages, no figures, submitted to J. Phys. A: Math & Gen | null | 10.1103/PhysRevA.60.121 | null | quant-ph | null | We establish a fluctuation-correlation theorem by relating the quantum
fluctuations in the generator of the parameter change to the time integral of
the quantum correlation function between the projection operator and force
operator of the ``fast'' system. By taking a cue from linear response theory we
relate the quantum fluctuation in the generator to the generalised
susceptibility. Relation between the open-path geometric phase, diagonal
elements of the quantum metric tensor and the force-force correlation function
is provided and the classical limit of the fluctuation-correlation theorem is
also discussed.
| [
{
"version": "v1",
"created": "Wed, 1 Apr 1998 12:42:24 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Pati",
"Arun K.",
"",
"B.A.R.C., Mumbai, India"
]
] |
quant-ph/9804004 | Oleg Prezhdo | Oleg V. Prezhdo and Peter J. Rossky | Relationship between quantum decoherence times and solvation dynamics in
condensed phase chemical systems | 10 pages, no figures, latex | Phys.Rev.Lett. 81 (1998) 5294-5297 | 10.1103/PhysRevLett.81.5294 | null | quant-ph | null | A relationship between the time scales of quantum coherence loss and
short-time solvent response for a solute/bath system is derived for a Gaussian
wave packet approximation for the bath. Decoherence and solvent response times
are shown to be directly proportional to each other, with the proportionality
coefficient given by the ratio of the thermal energy fluctuations to the
fluctuations in the system-bath coupling. The relationship allows the
prediction of decoherence times for condensed phase chemical systems from well
developed experimental methods.
| [
{
"version": "v1",
"created": "Wed, 1 Apr 1998 20:53:01 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Prezhdo",
"Oleg V.",
""
],
[
"Rossky",
"Peter J.",
""
]
] |
quant-ph/9804005 | Comman area for Thpd | Arun Kumar Pati (B.A.R.C., Mumbai, India) | Testing Bell's inequality using Aharonov-Casher effect | Latex, 6 pages, no figures, submitted to Phys. Rev. A | null | 10.1103/PhysRevA.58.R1 | null | quant-ph | null | We propose the Aharonov-Casher (AC) effect for four entangled spin-half
particles carrying magnetic moments in the presence of impenetrable line
charge. The four particle state undergoes AC phase shift in two causually
disconnected region which can show up in the correlations between different
spin states of distant particles. This correlation can violate Bell's
inequality, thus displaying the non-locality for four particle entangled states
in an objective way. Also, we have suggested how to control the AC phase shift
locally at two distant locations to test Bell's inequality. We belive that
although the single particle AC effect may not be non-local but the entangled
state AC effect is a non-local one.
| [
{
"version": "v1",
"created": "Thu, 2 Apr 1998 04:42:32 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Pati",
"Arun Kumar",
"",
"B.A.R.C., Mumbai, India"
]
] |
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