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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/9906041 | Yan Min | Ximing Fang, Xiwen Zhu, Mang Feng, Xi'an Mao and Fei Du | Experimental Implementaton of Dense Coding Using Nuclear Magnetic
Resonance | Some print errors have been corrected, 15 pages, RevTex, 11 figures | null | 10.1103/PhysRevA.61.022307 | null | quant-ph | null | Quantum dense coding has been demonstrated experimentally in terms of quantum
logic gates and circuits in quantum computation and NMR technique. Two bits of
information have been transmitted through manipulating one of the maximally
entangled two-state quantum pair, which is completely consistent with the
original ideal of Bennett-Wiesner proposal. Although information transmission
happens between spins over inter-atomic distance, the scheme of entanglement
transformation and measurement can be used in other processes of quantum
information and quantum computing.
| [
{
"version": "v1",
"created": "Mon, 14 Jun 1999 09:50:42 GMT"
},
{
"version": "v2",
"created": "Wed, 7 Jul 1999 10:06:56 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Fang",
"Ximing",
""
],
[
"Zhu",
"Xiwen",
""
],
[
"Feng",
"Mang",
""
],
[
"Mao",
"Xi'an",
""
],
[
"Du",
"Fei",
""
]
] |
quant-ph/9906042 | Richard L. Hall | Richard L. Hall | Spectral Comparison Theorem for the Dirac Equation | 9 pages. To appear in PRL | Phys.Rev.Lett. 83 (1999) 468-471 | 10.1103/PhysRevLett.83.468 | CUQM-75 | quant-ph math-ph math.MP | null | We consider a single particle which is bound by a central potential and obeys
the Dirac equation. We compare two cases in which the masses are the same but
Va < Vb, where V is the time-component of a vector potential. We prove
generally that for each discrete eigenvalue E whose corresponding (large and
small) radial wave functions have no nodes, it necessarily follows that Ea <
Eb. As an illustration, this general relativistic comparison theorem is applied
to approximate the Dirac spectrum generated by a screened-Coulomb potential.
| [
{
"version": "v1",
"created": "Mon, 14 Jun 1999 14:38:33 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Hall",
"Richard L.",
""
]
] |
quant-ph/9906043 | Habatwa Vincent Mweene | Habatwa Vincent Mweene (Physics Department, University of Zambia) | Vectors and Operators For Spin 1 Derived From First Principles | LaTeX, 27 pages.Replaced after thorough revision of notation and
improvement to some sections | null | null | UNZAPHYS-003 | quant-ph | null | In this paper, we extend to the case of spin 1 the method we have devised for
deriving generalized spin quantities from first principles, and which we
illustrated using the spin-1/2 case. Again, we not only derive from first
principles the standard results but we obtain new generalized results as well.
Our success in doing this shows that our method is of general validity and can
be applied to any value of J.
| [
{
"version": "v1",
"created": "Mon, 14 Jun 1999 15:29:37 GMT"
},
{
"version": "v2",
"created": "Sat, 1 Jul 2000 00:41:56 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mweene",
"Habatwa Vincent",
"",
"Physics Department, University of Zambia"
]
] |
quant-ph/9906044 | Uday Sukhatme | Avinash Khare and Uday Sukhatme | New Solvable and Quasi Exactly Solvable Periodic Potentials | 24 pages and 10 figures | J.Math.Phys. 40 (1999) 5473-5494 | 10.1063/1.533040 | UICHEP-TH/99-3 | quant-ph cond-mat hep-th | null | Using the formalism of supersymmetric quantum mechanics, we obtain a large
number of new analytically solvable one-dimensional periodic potentials and
study their properties. More specifically, the supersymmetric partners of the
Lame potentials ma(a+1)sn^2(x,m) are computed for integer values a=1,2,3,....
For all cases (except a=1), we show that the partner potential is distinctly
different from the original Lame potential, even though they both have the same
energy band structure. We also derive and discuss the energy band edges of the
associated Lame potentials pm sn^2(x,m)+qm cn^2(x,m)/ dn^2(x,m), which
constitute a much richer class of periodic problems. Computation of their
supersymmetric partners yields many additional new solvable and quasi exactly
solvable periodic potentials.
| [
{
"version": "v1",
"created": "Mon, 14 Jun 1999 17:01:09 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Khare",
"Avinash",
""
],
[
"Sukhatme",
"Uday",
""
]
] |
quant-ph/9906045 | Gennady Berman | Gennady P. Berman, Gary D. Doolen, and Vladimir I. Tsifrinovich | The Influence of Superpositional Wave Function Oscillations on Shor's
Quantum Algorithm | 4 pages, NO figures, revtex | Phys.Rev.Lett. 84 (2000) 1615-1618 | 10.1103/PhysRevLett.84.1615 | null | quant-ph | null | We investigate the influence of superpositional wave function oscillations on
the performance of Shor's quantum algorithm for factorization of integers. It
is shown that the wave function oscillations can destroy the required quantum
interference. This undesirable effect can be routinely eliminated using a
resonant pulse implementation of quantum computation, but requires special
analysis for non-resonant implementations.
| [
{
"version": "v1",
"created": "Mon, 14 Jun 1999 17:19:10 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Berman",
"Gennady P.",
""
],
[
"Doolen",
"Gary D.",
""
],
[
"Tsifrinovich",
"Vladimir I.",
""
]
] |
quant-ph/9906046 | Cathy Knudsen | A. A. Broyles (University of Florida, Gainesville, FL, USA) | Derivation of the Pauli exchange principle | 5 pages, 1 figure | null | null | null | quant-ph | null | Wave functions are generally written with arguments consisting of sets of
``particle'' coordinates and quantum numbers. Pauli derived a principle
governing the exchange of pairs of sets that differ only in their spatial and
spin component $(m_s)$ coordinates. This principle states that an exchange of
two of these sets produces the same wave function except for its being
multiplied by a factor of $(-1)^{2s}$. Pauli's proof is based upon quantum
field operators and is difficult to understand. A much simpler proof, making
use of properties of wave functions, is presented here.
| [
{
"version": "v1",
"created": "Mon, 14 Jun 1999 20:25:25 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Broyles",
"A. A.",
"",
"University of Florida, Gainesville, FL, USA"
]
] |
quant-ph/9906047 | Majid Abolhasani | M. Abolhasani and M. Golshani | The Best Copenhagen Tunneling Times | 16 pages, 5 figures | null | null | IPM/p-99/006 | quant-ph | null | Recently, people have caculated tunneling's characteristic times within
Bohmian mechanics. Contrary to some characteristic times defined within the
framework of the standard interpretation of quantum mechanics, these have
reasonable values. Here, we introduce one of available definitions for
tunnelling's characteristic times within the standard interpretation as the
best definition that can be accepted for the tunneling times. We show that, due
to experimental limitations, Bohmian mechanics leads to same tunneling times.
| [
{
"version": "v1",
"created": "Tue, 15 Jun 1999 05:09:30 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Abolhasani",
"M.",
""
],
[
"Golshani",
"M.",
""
]
] |
quant-ph/9906048 | Ioan Sturzu | Ioan Sturzu, Gelu Nita ('Transilvania' University, Brasov, Romania,
Department of Physics) | Unsharpness in the Stern-Gerlach device via stochastic perturbation in
the Hamiltonian | null | null | null | null | quant-ph | null | This paper has been withdrawn by the author(s), due a crucial i-number error
in Eqn. 18.
| [
{
"version": "v1",
"created": "Tue, 15 Jun 1999 05:25:52 GMT"
},
{
"version": "v2",
"created": "Sat, 19 Jun 1999 01:28:56 GMT"
},
{
"version": "v3",
"created": "Mon, 12 Jul 1999 02:55:19 GMT"
},
{
"version": "v4",
"created": "Fri, 10 May 2002 23:45:46 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sturzu",
"Ioan",
"",
"'Transilvania' University, Brasov, Romania,\n Department of Physics"
],
[
"Nita",
"Gelu",
"",
"'Transilvania' University, Brasov, Romania,\n Department of Physics"
]
] |
quant-ph/9906049 | Nicolas Gisin | N. Gisin and H. Zbinden | Bell inequality and the locality loophole: Active versus passive
switches | 6 pages, 1 figure | Phys.Lett. A264 (1999) 103-107 | 10.1016/S0375-9601(99)00807-5 | null | quant-ph | null | All experimental tests of the violation of Bell's inequality suffer from some
loopholes. We show that the locality loophole is not independent of the
detection loophole: in experiments using low efficient detectors, the locality
loophole can be closed equivalently using active or passive switches.
| [
{
"version": "v1",
"created": "Tue, 15 Jun 1999 08:35:18 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Gisin",
"N.",
""
],
[
"Zbinden",
"H.",
""
]
] |
quant-ph/9906050 | Nikolay Vitanov | N. V. Vitanov | Pulse-order invariance of the initial-state population in multistate
chains driven by delayed laser pulses | 3 pages, 1 figure, twocolumn REVTeX | null | 10.1103/PhysRevA.60.3308 | null | quant-ph | null | This paper shows that under certain symmetry conditions the probability of
remaining in the initial state (the probability of no transition) in a
chainwise-connected multistate system driven by two or more delayed laser
pulses does not depend on the pulse order.
| [
{
"version": "v1",
"created": "Tue, 15 Jun 1999 12:34:25 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Vitanov",
"N. V.",
""
]
] |
quant-ph/9906051 | Nikolay Vitanov | N. V. Vitanov, B. W. Shore, R. G. Unanyan, and K. Bergmann | Measuring a coherent superposition | 7 pages, 1 figure, twocolumn REVTeX | null | 10.1016/S0030-4018(99)00545-3 | null | quant-ph | null | We propose a simple method for measuring the populations and the relative
phase in a coherent superposition of two atomic states. The method is based on
coupling the two states to a third common (excited) state by means of two laser
pulses, and measuring the total fluorescence from the third state for several
choices of the excitation pulses.
| [
{
"version": "v1",
"created": "Tue, 15 Jun 1999 13:04:33 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Vitanov",
"N. V.",
""
],
[
"Shore",
"B. W.",
""
],
[
"Unanyan",
"R. G.",
""
],
[
"Bergmann",
"K.",
""
]
] |
quant-ph/9906052 | Jan Perina Jr | Jan Perina Jr | Properties of pulsed entangled two-photon fields | LATEX2e, 8 pages, 9 PostScript figures | Eur.Phys.J.D7:235,1999 | 10.1007/s100530050370 | null | quant-ph | null | The dependence of one- and two-photon characteristics of pulsed entangled
two-photon fields generated in spontaneous parametric down-conversion on the
pump-pulse properties (shape of the pump-pulse spectrum and its internal
structure) is examined. It is shown that entangled two-photon fields with
defined properties can be generated. A general relation between the spectra of
the down-converted fields is established. As a special case interference of two
partially overlapping pulsed two-photon fields is studied. Fourth-order
interference pattern of entangled two-photon fields is investigated in the
polarization analog of the Hong-Ou-Mandel interferometer.
| [
{
"version": "v1",
"created": "Tue, 15 Jun 1999 14:11:16 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Perina",
"Jan",
"Jr"
]
] |
quant-ph/9906053 | Wang Zhen | Zhen Wang | Calculation of the Deflection of Light Ray near the Sun with
Quantum-corrected Newton's Gravitation Law | tciLatex, 5 pages. no figure | null | null | LNU-99-06 | quant-ph | null | The deflection of light ray passing near the Sun is calculated with
quantum-corrected Newton's gravitation law. The satisfactory result suggests
that there may exist other theoretical possibilities besides the theory of
relativity.
| [
{
"version": "v1",
"created": "Wed, 16 Jun 1999 01:27:06 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Wang",
"Zhen",
""
]
] |
quant-ph/9906054 | Tal Mor | P. Oscar Boykin, Tal Mor, Matthew Pulver, Vwani Roychowdhury, and
Farrokh Vatan | On Universal and Fault-Tolerant Quantum Computing | 10 pages, Latex. Emails addresses {boykin, talmo, pulver, vwani,
vatan}@ee.ucla.edu | null | null | null | quant-ph | null | A novel universal and fault-tolerant basis (set of gates) for quantum
computation is described. Such a set is necessary to perform quantum
computation in a realistic noisy environment. The new basis consists of two
single-qubit gates (Hadamard and ${\sigma_z}^{1/4}$), and one double-qubit gate
(Controlled-NOT). Since the set consisting of Controlled-NOT and Hadamard gates
is not universal, the new basis achieves universality by including only one
additional elementary (in the sense that it does not include angles that are
irrational multiples of $\pi$) single-qubit gate, and hence, is potentially the
simplest universal basis that one can construct. We also provide an alternative
proof of universality for the only other known class of universal and
fault-tolerant basis proposed by Shor and by Kitaev.
| [
{
"version": "v1",
"created": "Wed, 16 Jun 1999 02:50:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Boykin",
"P. Oscar",
""
],
[
"Mor",
"Tal",
""
],
[
"Pulver",
"Matthew",
""
],
[
"Roychowdhury",
"Vwani",
""
],
[
"Vatan",
"Farrokh",
""
]
] |
quant-ph/9906055 | George Pogosyan | E.G. Kalnins, W. Miller, Jr., G. S. Pogosyan | Coulomb-oscillator duality in spaces of constant curvature | 33 pages, LaTeX file | J.Math.Phys.41:2629-2657,2000 | 10.1063/1.533263 | null | quant-ph | null | In this paper we construct generalizations to spheres of the well known
Levi-Civita, Kustaanheimo-Steifel and Hurwitz regularizing transformations in
Euclidean spaces of dimensions 2, 3 and 5. The corresponding classical and
quantum mechanical analogues of the Kepler-Coulomb problem on these spheres are
discussed.
| [
{
"version": "v1",
"created": "Wed, 16 Jun 1999 07:08:35 GMT"
}
] | 2012-08-27T00:00:00 | [
[
"Kalnins",
"E. G.",
""
],
[
"Miller,",
"W.",
"Jr."
],
[
"Pogosyan",
"G. S.",
""
]
] |
quant-ph/9906056 | Guohong Yang | Guang-jiong Ni | Let the New Experiments Tell the Quantum Theory | Latex, 14 pages, 1 figure | null | null | null | quant-ph | null | Several new physics experiments in 1998 were performed and analyzed to show
the subtlety of quantum theory, including the "wave-particle duality" and the
non-separability of two-particle entangled state. Here it is shown that the
measurement is bound to change the object by destroying the original quantum
coherence between the object and its environment. So the "physical reality"
should be defined at two levels, the "thing in itself" and the "thing for us".
The wave function in quantum mechanics is just playing the role for connecting
the two levels of matter via the fictitious measurement.
| [
{
"version": "v1",
"created": "Wed, 16 Jun 1999 10:46:13 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ni",
"Guang-jiong",
""
]
] |
quant-ph/9906057 | null | Carl M. Bender (Washington U.), Stefan Boettcher (Emory U.), H. F.
Jones (Imperial C.), Van M. Savage (Washington U.) | Complex Square Well --- A New Exactly Solvable Quantum Mechanical Model | 7 pages, Revtex, 2 eps-figures enclosed | J.Phys.A32:6771-6781,1999 | 10.1088/0305-4470/32/39/305 | null | quant-ph cond-mat hep-th math-ph math.MP | null | Recently, a class of PT-invariant quantum mechanical models described by the
non-Hermitian Hamiltonian $H=p^2+x^2(ix)^\epsilon$ was studied. It was found
that the energy levels for this theory are real for all $\epsilon\geq0$. Here,
the limit as $\epsilon\to\infty$ is examined. It is shown that in this limit,
the theory becomes exactly solvable. A generalization of this Hamiltonian,
$H=p^2+x^{2M}(ix)^\epsilon$ (M=1,2,3,...) is also studied, and this
PT-symmetric Hamiltonian becomes exactly solvable in the large-\epsilon limit
as well. In effect, what is obtained in each case is a complex analog of the
Hamiltonian for the square well potential. Expansions about the large-\epsilon
limit are obtained.
| [
{
"version": "v1",
"created": "Wed, 16 Jun 1999 15:22:05 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Bender",
"Carl M.",
"",
"Washington U."
],
[
"Boettcher",
"Stefan",
"",
"Emory U."
],
[
"Jones",
"H. F.",
"",
"Imperial C."
],
[
"Savage",
"Van M.",
"",
"Washington U."
]
] |
quant-ph/9906058 | Eliahu Comay | E. Comay (School of Physics and Astronomy, Tel Aviv University, Tel
Aviv, Israel) | The Role of Inert Objects in Quantum Mechanical Phase | 7 pages, no figures, Latex | Phys.Lett. A250 (1998) 12-14 | 10.1016/S0375-9601(98)00836-6 | TAUP 2513-98 | quant-ph | null | Quantum mechanical foundations of the polarized neutron phase shift
experiment are discussed. The fact that the neutron retains its ground state
throughout the experiment is shown to be crucial for the phase shift obtained.
| [
{
"version": "v1",
"created": "Wed, 16 Jun 1999 15:30:14 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Comay",
"E.",
"",
"School of Physics and Astronomy, Tel Aviv University, Tel\n Aviv, Israel"
]
] |
quant-ph/9906059 | Yaakov S. Weinstein | Yaakov S. Weinstein, Seth Lloyd, David G. Cory | Implementation of the Quantum Fourier Transform | 6 pages, 2 figures | Phys.Rev.Lett.86:1889,2001 | 10.1103/PhysRevLett.86.1889 | null | quant-ph | null | The quantum Fourier transform (QFT) has been implemented on a three bit
nuclear magnetic resonance (NMR) quantum computer, providing a first step
towards the realization of Shor's factoring and other quantum algorithms.
Implementation of the QFT is presented with fidelity measures, and state
tomography. Experimentally realizing the QFT is a clear demonstration of NMR's
ability to control quantum systems.
| [
{
"version": "v1",
"created": "Wed, 16 Jun 1999 15:46:41 GMT"
}
] | 2009-01-23T00:00:00 | [
[
"Weinstein",
"Yaakov S.",
""
],
[
"Lloyd",
"Seth",
""
],
[
"Cory",
"David G.",
""
]
] |
quant-ph/9906060 | Paolo Facchi | P. Facchi, S. Pascazio, A. Scardicchio | Quantum chaos induced by measurements | 9 pages, 1 figure. To appear in the Proceedings of the Symposium on
"Mathematical Aspects of Quantum Information and Quantum Chaos," Kyoto,
Japan, 1999 | null | null | null | quant-ph | null | We study the dynamics of a "kicked" quantum system undergoing repeated
measurements of momentum. A diffusive behavior is obtained for a large class of
Hamiltonians, even when the dynamics of the classical counterpart is not
chaotic. These results can be interpreted in classical terms by making use of a
"randomized" classical map. We compute the transition probability for the
action variable and consider the semiclassical limit.
| [
{
"version": "v1",
"created": "Wed, 16 Jun 1999 17:00:16 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Facchi",
"P.",
""
],
[
"Pascazio",
"S.",
""
],
[
"Scardicchio",
"A.",
""
]
] |
quant-ph/9906061 | Cynthia K. W. Ma | Cynthia K.W. Ma | Causation & Physics | Invited talk delivered at the III Adriatico Research Conference on
Quantum Interferometry, ICTP, March 1-5,1999. Paper submitted to the
proceedings. 10 pages, 10 eps figures | Fortsch.Phys. 48 (2000) 689-699 | 10.1002/(SICI)1521-3978(200005)48:5/7<689::AID-PROP689>3.0.CO;2-H | null | quant-ph physics.ed-ph | null | Philosophical analyses of causation take many forms but one major difficulty
they all aim to address is that of the spatio-temporal continuity between
causes and their effects. Bertrand Russell in 1913 brought the problem to its
most transparent form and made it a case against the notion of causation in
physics. In this essay, I focus on this subject of causal continuity and its
related issues in classical and quantum physics.
| [
{
"version": "v1",
"created": "Wed, 16 Jun 1999 21:02:55 GMT"
}
] | 2016-10-26T00:00:00 | [
[
"Ma",
"Cynthia K. W.",
""
]
] |
quant-ph/9906062 | Umar Mohideen | Anushree Roy, Chiung-Yuan Lin and U. Mohideen | Improved Precision Measurement of the Casimir Force | null | Phys.Rev.D60:111101,1999 | 10.1103/PhysRevD.60.111101 | null | quant-ph | null | We report an improved precision measurement of the Casimir force. The force
is measured between a large Al coated sphere and flat plate using an Atomic
Force Microscope. The primary experimental improvements include the use of
smoother metal coatings, reduced noise, lower systematic errors and independent
measurement of surface separations. Also the complete dielectric spectrum of
the metal is used in the theory. The average statistical precision remains at
the same 1% of the forces measured at the closest separation.
| [
{
"version": "v1",
"created": "Wed, 16 Jun 1999 23:45:48 GMT"
},
{
"version": "v2",
"created": "Thu, 17 Jun 1999 01:14:02 GMT"
},
{
"version": "v3",
"created": "Tue, 4 Jan 2000 19:48:32 GMT"
}
] | 2009-07-09T00:00:00 | [
[
"Roy",
"Anushree",
""
],
[
"Lin",
"Chiung-Yuan",
""
],
[
"Mohideen",
"U.",
""
]
] |
quant-ph/9906063 | Eliahu Comay | E. Comay (School of Physics and Astronomy, Tel Aviv University, Tel
Aviv, Israel) | Interrelations Between the Neutron's Magnetic Interactions and the
Magnetic Aharonov-Bohm Effect | 18 pages, 1 postscript figure, Latex | null | 10.1103/PhysRevA.62.042102 | TAUP 2543-98 | quant-ph math.QA | null | It is proved that the phase shift of a polarized neutron interacting with a
spatially uniform time-dependent magnetic field, demonstrates the same physical
principles as the magnetic Aharonov-Bohm effect. The crucial role of inert
objects is explained, thereby proving the quantum mechanical nature of the
effect. It is also proved that the nonsimply connectedness of the field-free
region is not a profound property of the system and that it cannot be regarded
as a sufficient condition for a nonzero phase shift.
| [
{
"version": "v1",
"created": "Thu, 17 Jun 1999 12:39:12 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Comay",
"E.",
"",
"School of Physics and Astronomy, Tel Aviv University, Tel\n Aviv, Israel"
]
] |
quant-ph/9906064 | Ron Folman | R.Folman, J.Schmiedmayer and H.Ritsch | On the observation of decoherence with a movable mirror | 11 pages, 5 figures | Z.Naturforsch. A56 (2001) 140-144 | null | null | quant-ph | null | Following almost a century of debate on possible `independent of measurement'
elements of reality, or `induced' elements of reality - originally invoked as
an ad-hoc collapse postulate, we propose a novel line of interference
experiments which may be able to examine the regime of induced elements of
reality. At the basis of the proposed experiment, lies the hypothesis that all
models of 'induced' elements of reality should exhibit symmetry breaking within
quantum evolution. The described {\em symmetry experiment} is thus aimed at
being able to detect and resolve symmetry breaking signatures.
| [
{
"version": "v1",
"created": "Thu, 17 Jun 1999 08:58:41 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Folman",
"R.",
""
],
[
"Schmiedmayer",
"J.",
""
],
[
"Ritsch",
"H.",
""
]
] |
quant-ph/9906065 | Lev Kaplan | L. Kaplan | Quantization Ambiguity, Ergodicity, and Semiclassics | 4 pages, with 2 figures | New J.Phys. 4 (2002) 90 | 10.1088/1367-2630/4/1/390 | null | quant-ph chao-dyn nlin.CD | null | A simple argument shows that eigenstates of a classically ergodic system are
individually ergodic on coarse-grained scales. This has implications for the
quantization ambiguity in ergodic systems: the difference between alternative
quantizations is suppressed compared with the $O(\hbar^2)$ ambiguity in the
integrable case. For two-dimensional ergodic systems in the high-energy regime,
individual eigenstates are independent of the choice of quantization procedure,
in contrast with the regular case, where even the ordering of eigenlevels is
ambiguous. Surprisingly, semiclassical methods are shown to be much more
precise for chaotic than for integrable systems.
| [
{
"version": "v1",
"created": "Thu, 17 Jun 1999 22:43:41 GMT"
}
] | 2009-08-14T00:00:00 | [
[
"Kaplan",
"L.",
""
]
] |
quant-ph/9906066 | Timothy C. Ralph | R.E.S.Polkinghorne and T.C.Ralph | Entanglement swapping using continuous variables | 8 pages, 4 figures | Phys.Rev.Lett.83:2095-2099,1999 | 10.1103/PhysRevLett.83.2095 | null | quant-ph | null | We investigate the efficacy with which entanglement can be teleported using a
continuous measurement scheme. We show that by using the correct gain for the
classical channel the degree of violation of locality that can be demonstrated
(using a CH type inequality) is {\it not} a function of the level of
entanglement squeezing used in the teleportation. This is possible because a
gain condition can always be choosen such that passage through the teleporter
is equivalent to pure attenuation of the input field.
| [
{
"version": "v1",
"created": "Fri, 18 Jun 1999 04:24:24 GMT"
}
] | 2009-01-23T00:00:00 | [
[
"Polkinghorne",
"R. E. S.",
""
],
[
"Ralph",
"T. C.",
""
]
] |
quant-ph/9906067 | Massimiliano F. Sacchi | G. M. D'Ariano, M. Rubin, M. F. Sacchi, and Y. Shih | Quantum tomography of the GHZ state | Paper submitted to the proceedings of the III Adriatico Research
Conference on Quantum Interferometry, ICTP, March 1-5,1999. 5 pages, 3 eps
figures | Fortsch.Phys. 48 (2000) 599 | 10.1002/(SICI)1521-3978(200005)48:5/7<599::AID-PROP599>3.0.CO;2-H | null | quant-ph | null | We present a method of generation of the Greenberger-Horne-Zeilinger state
involving type II and type I parametric downconversion, and triggering
photodetectors. The state generated by the proposed experimental set-up can be
reconstructed through multi-mode quantum homodyne tomography. The feasibility
of the measurement is studied on the basis of Monte-Carlo simulations.
| [
{
"version": "v1",
"created": "Fri, 18 Jun 1999 08:12:54 GMT"
}
] | 2017-04-26T00:00:00 | [
[
"D'Ariano",
"G. M.",
""
],
[
"Rubin",
"M.",
""
],
[
"Sacchi",
"M. F.",
""
],
[
"Shih",
"Y.",
""
]
] |
quant-ph/9906068 | Michael Mensky | J. Audretsch, M. B. Mensky, A. D. Panov | Zeno effect preventing Rabi transitions onto an unstable energy level | 13 pages, Latex, 2 EPS figures | Phys.Lett. A261 (1999) 44-50 | 10.1016/S0375-9601(99)00569-1 | null | quant-ph | null | We consider a driven 2-level system with one level showing spontaneous decay
to an otherwise uncoupled third level. Rabi transitions to the unstable level
are strongly damped. This simple configuration can be used to demonstrate and
to explore the quantum Zeno effect leading to a freezing of the system to the
initial level. A comparison with repeated projection measurements is given. A
treatment within a phenomenological theory of continuous measurements is
sketched. The system visualizes the important role of null measurements
(negative result measurements) and may serve as a good example for a truly
continuous measurement.
| [
{
"version": "v1",
"created": "Fri, 18 Jun 1999 08:51:51 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Audretsch",
"J.",
""
],
[
"Mensky",
"M. B.",
""
],
[
"Panov",
"A. D.",
""
]
] |
quant-ph/9906069 | Victor Zadkov | Boris Grishanin, Victor Zadkov | Natural capacity of a system of two two-level atoms as a quantum
information channel | 8 pages, 2 figures, source in RevTeX, figures in PostScript | Laser Phys. 8 (1998) 1074-1080 | null | null | quant-ph | null | A system of two closely spaced atoms interacting through a vacuum
electromagnetic field is considered. It is demonstrated that radiative decay in
such a system resulting from photon exchange gives rise to a definite amount of
information related to interatomic communication. Joint distributions of
detection probabilities of atomic quanta and the corresponding amount of
communication information are calculated.
| [
{
"version": "v1",
"created": "Fri, 18 Jun 1999 15:49:56 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Grishanin",
"Boris",
""
],
[
"Zadkov",
"Victor",
""
]
] |
quant-ph/9906070 | Luis Santos | Luis Santos and Maciej Lewenstein | Collisional effects on the collective laser cooling of trapped bosonic
gases | 9 pages, 5 figures | null | 10.1007/s003400050821 | null | quant-ph | null | We analyse the effects of atom-atom collisions on collective laser cooling
scheme. We derive a quantum Master equation which describes the laser cooling
in presence of atom-atom collisions in the weak-condensation regime. Using such
equation, we perform Monte Carlo simulations of the population dynamics in one
and three dimensions. We observe that the ground-state laser-induced
condensation is maintained in the presence of collisions. Laser cooling causes
a transition from a Bose-Einstein distribution describing collisionally induced
equilibrium,to a distribution with an effective zero temperature. We analyse
also the effects of atom-atom collisions on the cooling into an excited state
of the trap.
| [
{
"version": "v1",
"created": "Fri, 18 Jun 1999 16:05:34 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Santos",
"Luis",
""
],
[
"Lewenstein",
"Maciej",
""
]
] |
quant-ph/9906071 | Kazutomu Shiokawa | K. Shiokawa | On Multistep Bose-Einstein Condensation in Anisotropic Traps | 26 pages, 7 figures, revised version, to appear in Jour. Phys. A | J.Phys.A33:487-506,2000 | 10.1088/0305-4470/33/3/305 | umdpp 99-076 | quant-ph cond-mat.stat-mech | null | Multistep Bose-Einstein condensation of an ideal Bose gas in anisotropic
harmonic atom traps is studied. In the presence of strong anisotropy realized
by the different trap frequency in each direction, finite size effect dictates
a series of dimensional crossovers into lower-dimensional excitations. Two-step
condensation and the dynamical reduction of the effective dimension can appear
in three separate steps. When the multistep behavior occurs, the occupation
number of atoms excited in each dimension is shown to behave similarly as a
function of the temperature.
| [
{
"version": "v1",
"created": "Fri, 18 Jun 1999 19:19:45 GMT"
},
{
"version": "v2",
"created": "Mon, 13 Dec 1999 02:09:25 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Shiokawa",
"K.",
""
]
] |
quant-ph/9906072 | Timothy C. Ralph | T.C.Ralph | The Mach-Zehnder and the Teleporter | 4 pages, 5 figures | Phys.Rev.A61:044301,2000 | 10.1103/PhysRevA.61.044301 | null | quant-ph | null | We suggest a self-testing teleportation configuration for photon q-bits based
on a Mach-Zehnder interferometer. That is, Bob can tell how well the input
state has been teleported without knowing what that input state was. One could
imagine building a "locked" teleporter based on this configuration. The
analysis is performed for continuous variable teleportation but the arrangement
could equally be applied to discrete manipulations.
| [
{
"version": "v1",
"created": "Mon, 21 Jun 1999 05:12:26 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Ralph",
"T. C.",
""
]
] |
quant-ph/9906073 | Tal Mor | Tal Mor | Quantum memory in quantum cryptography | D.Sc. (Ph.D) Thesis; April 1997; Technion, Haifa, Israel. 107 pages,
Latex. The results of chapters 2-4 (security of QKD), and chapter 5 (QKD via
quantum memory) appeared elsewhere in the quant-physics archive, and were
published in journals (see ref. 15, 19, 20 and 21; ref 21 is now PRL, 79,
p.4034, 1997). Chapter 6 contains the idea of quantum privacy amplification
based on quantum error correction, and the surprising idea that ``quantum
repeaters'' can be used for QKD. This chapter is a much improved version of
quant-ph/9608025 and these results were not published | null | null | null | quant-ph | null | [Shortened abstract:] This thesis investigates the importance of quantum
memory in quantum cryptography, concentrating on quantum key distribution
schemes.
In the hands of an eavesdropper -- a quantum memory is a powerful tool,
putting in question the security of quantum cryptography; Classical privacy
amplification techniques, used to prove security against less powerful
eavesdroppers, might not be effective when the eavesdropper can keep quantum
states for a long time. In this work we suggest a possible direction for
approaching this problem. We define strong attacks of this type, and show
security against them, suggesting that quantum cryptography is secure. We start
with a complete analysis regarding the information about a parity bit (since
parity bits are used for privacy amplification). We use the results regarding
the information on parity bits to prove security against very strong
eavesdropping attacks, which uses quantum memories and all classical data
(including error correction codes) to attack the final key directly.
In the hands of the legitimate users, a quantum memory is also a useful tool.
We suggest a new type of quantum key distribution scheme where quantum memories
are used instead of quantum channels. This scheme is especially adequate for
networks of many users. The use of quantum memory also allows reducing the
error rate to improve large scale quantum cryptography, and to enable the
legitimate users to work with reasonable error rate.
| [
{
"version": "v1",
"created": "Mon, 21 Jun 1999 07:18:12 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mor",
"Tal",
""
]
] |
quant-ph/9906074 | Tal Mor | Gilles Brassard, Tal Mor, and Barry C. Sanders | Quantum cryptography via parametric downconversion | 6 pages, Latex (a special style file is attached). Presented in
QCM'98 conference. Similar results regarding the insecurity of weak-pulse
schemes were also presented by Norbert Lutkenhaus in the same conference | null | 10.1007/0-306-47097-7_51 | null | quant-ph | null | The use of quantum bits (qubits) in cryptography holds the promise of secure
cryptographic quantum key distribution schemes. It is based usually on
single-photon polarization states. Unfortunately, the implemented ``qubits'' in
the usual weak pulse experiments are not true two-level systems, and quantum
key distribution based on these imperfect qubits is totally insecure in the
presence of high (realistic) loss rate. In this work, we investigate another
potential implementation: qubits generated using a process of parametric
downconversion. We find that, to first (two-photon) and second (four-photon)
order in the parametric downconversion small parameter, this implementation of
quantum key distribution is equivalent to the theoretical version.
Once realistic measurements are taken into account, quantum key distribution
based on parametric downconversion suffers also from sensitivity to extremely
high (nonrealistic) losses. By choosing the small parameter of the process
according to the loss rates, both implementations of quantum key distribution
can in principle become secure against the attack studied in this paper.
However, adjusting the small parameter to the required levels seems to be
impractical in the weak pulse process. On the other hand, this can easily be
done in the parametric downconversion process, making it a much more promising
implementation.
| [
{
"version": "v1",
"created": "Mon, 21 Jun 1999 07:25:38 GMT"
}
] | 2015-05-06T00:00:00 | [
[
"Brassard",
"Gilles",
""
],
[
"Mor",
"Tal",
""
],
[
"Sanders",
"Barry C.",
""
]
] |
quant-ph/9906075 | Samuel L. Braunstein | P. van Loock and Samuel L. Braunstein | Unconditional teleportation of continuous-variable entanglement | 4 pages, 2 figures, published version, title changed | Phys. Rev. A 61, 010302(R) (2000) | 10.1103/PhysRevA.61.010302 | null | quant-ph | null | We give a protocol and criteria for demonstrating unconditional teleportation
of continuous-variable entanglement (i.e., entanglement swapping). The initial
entangled states are produced with squeezed light and linear optics. We show
that any nonzero entanglement (any nonzero squeezing) in both of two
entanglement sources is sufficient for entanglement swapping to occur. In fact,
realization of continuous-variable entanglement swapping is possible using only
{\it two} single-mode squeezed states.
| [
{
"version": "v1",
"created": "Mon, 21 Jun 1999 08:38:32 GMT"
},
{
"version": "v2",
"created": "Mon, 19 Jun 2000 11:45:31 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"van Loock",
"P.",
""
],
[
"Braunstein",
"Samuel L.",
""
]
] |
quant-ph/9906076 | Pavel Stovicek | P. Stovicek | Several remarks on ``Comments'' by A. Moroz | to appear in Europhys. Lett | Europhys.Lett. 46 (1999) 275 | 10.1209/epl/i1999-00384-1 | null | quant-ph | null | We make a couple of remarks on ``Comments'' due to A. Moroz which were
addressed to our recent letter "Differential cross section for Aharonov-Bohm
effect with non standard boundary conditions", Europhys. Lett. 44 (1998) 403.
| [
{
"version": "v1",
"created": "Mon, 21 Jun 1999 11:06:50 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Stovicek",
"P.",
""
]
] |
quant-ph/9906077 | Massimiliano F. Sacchi | G. M. D'Ariano, L. Maccone, M. G. A. Paris, and M. F. Sacchi | State preparation by photon filtering | Paper submitted to the proceedings of the III Adriatico Research
Conference on Quantum Interferometry, ICTP, March 1-5,1999. 9 pages, 10 eps
figures | Fortsch.Phys. 48 (2000) 671 | 10.1002/(SICI)1521-3978(200005)48:5/7<671::AID-PROP671>3.0.CO;2-G | null | quant-ph | null | We propose a setup capable of generating Fock states of a single mode
radiation field. The scheme is based on coupling the signal field to a ring
cavity through cross-Kerr phase modulation, and on conditional ON-OFF
photodetection at the output cavity mode. The same setup allows to prepare
selected superpositions of Fock states and entangled two-mode states.
Remarkably, the detector's quantum efficiency does not affect the reliability
of the state synthesis.
| [
{
"version": "v1",
"created": "Mon, 21 Jun 1999 14:54:21 GMT"
}
] | 2016-10-26T00:00:00 | [
[
"D'Ariano",
"G. M.",
""
],
[
"Maccone",
"L.",
""
],
[
"Paris",
"M. G. A.",
""
],
[
"Sacchi",
"M. F.",
""
]
] |
quant-ph/9906078 | Avi Marhavka | A. Marchewka, Z. Schuss | Measurement as Absorption of Feynman Trajectories: Collapse of the Wave
Function Can be Avoided | 20 pages, latex, no figures | Phys.Rev.A65:042112,2002 | 10.1103/PhysRevA.65.042112 | TAUP 2579/99 | quant-ph | null | We define a measuring device (detector) of the coordinate of quantum particle
as an absorbing wall that cuts off the particle's wave function. The wave
function in the presence of such detector vanishes on the detector. The trace
the absorbed particles leave on the detector is identifies as the absorption
current density on the detector. This density is calculated from the solution
of Schr\"odinger's equation with a reflecting boundary at the detector. This
current density is not the usual Schr\"odinger current density. We define the
probability distribution of the time of arrival to a detector in terms of the
absorption current density. We define coordinate measurement by an absorbing
wall in terms of 4 postulates. We postulate, among others, that a quantum
particle has a trajectory. In the resulting theory the quantum mechanical
collapse of the wave function is replaced with the usual collapse of the
probability distribution after observation. Two examples are presented, that of
the slit experiment and the slit experiment with absorbing boundaries to
measure time of arrival. A calculation is given of the two dimensional
probability density function of a free particle from the measurement of the
absorption current on two planes.
| [
{
"version": "v1",
"created": "Mon, 21 Jun 1999 16:18:52 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Marchewka",
"A.",
""
],
[
"Schuss",
"Z.",
""
]
] |
quant-ph/9906079 | Dmitry Kamenev | G. P. Berman, V. Ya. Demikhovskii, D. I. Kamenev | Symmetry of Quantum Phase Space in a Degenerate Hamiltonian System | 11 pages LaTex, including 2 Postscript figures | null | 10.1063/1.1285965 | null | quant-ph chao-dyn nlin.CD | null | Using Husimi function approach, we study the ``quantum phase space'' of a
harmonic oscillator interacting with a plane monochromatic wave. We show that
in the regime of weak chaos, the quantum system has the same symmetry as the
classical system. Analytical results agree with the results of numerical
calculations.
| [
{
"version": "v1",
"created": "Mon, 21 Jun 1999 19:36:56 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Berman",
"G. P.",
""
],
[
"Demikhovskii",
"V. Ya.",
""
],
[
"Kamenev",
"D. I.",
""
]
] |
quant-ph/9906080 | Lucien Hardy | Ernesto Galvao and Lucien Hardy | Building multiparticle states with teleportation | 11 pages, 1 figure. Version 2 contains an example for which protocol
P3 is better than protocol P2. Correction to references in version 3 | Phys.Rev.A62:012309,2000 | 10.1103/PhysRevA.62.012309 | null | quant-ph | null | We describe a protocol which can be used to generate any N-partite pure
quantum state using Einstein-Podolsky-Rosen (EPR) pairs. This protocol employs
only local operations and classical communication between the N parties
(N-LOCC). In particular, we rely on quantum data compression and teleportation
to create the desired state. This protocol can be used to obtain upper bounds
for the bipartite entanglement of formation of an arbitrary N-partite pure
state, in the asymptotic limit of many copies. We apply it to a few
multipartite states of interest, showing that in some cases it is not optimal.
Generalizations of the protocol are developed which are optimal for some of the
examples we consider, but which may still be inefficient for arbitrary states.
| [
{
"version": "v1",
"created": "Mon, 21 Jun 1999 21:05:09 GMT"
},
{
"version": "v2",
"created": "Thu, 22 Jul 1999 14:06:25 GMT"
},
{
"version": "v3",
"created": "Sun, 25 Jul 1999 11:18:26 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Galvao",
"Ernesto",
""
],
[
"Hardy",
"Lucien",
""
]
] |
quant-ph/9906081 | null | Soon-Tae Hong, Won Tae Kim, Young-Jai Park | Improved Dirac quantization of a free particle | 12 pages, revtex, no figures, minor corrections, title is changed | Mod.Phys.Lett. A15 (2000) 1915-1922 | 10.1142/S0217732300002450 | null | quant-ph hep-th | null | In the framework of Dirac quantization with second class constraints, a free
particle moving on the surface of a $(d-1)-$dimensional sphere has an ambiguity
in the energy spectrum due to the arbitrary shift of canonical momenta. We
explicitly show that this spectrum obtained by the Dirac method can be
consistent with the result of the Batalin-Fradkin-Tyutin formalism, which is an
improved
Dirac method, at the level of the first-class constraint by fixing the
ambiguity, and discuss its physical consequences.
| [
{
"version": "v1",
"created": "Tue, 22 Jun 1999 08:29:59 GMT"
},
{
"version": "v2",
"created": "Tue, 28 Nov 2000 04:35:14 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Hong",
"Soon-Tae",
""
],
[
"Kim",
"Won Tae",
""
],
[
"Park",
"Young-Jai",
""
]
] |
quant-ph/9906082 | Christian Helm | H. Geiger, G. Obermair, Ch. Helm | Classical behaviour of many-body systems in Bohmian Quantum Mechanics | 11 pages, 2 postscript figures, elsart.cls, submitted to Phys. Lett.
A | null | null | null | quant-ph cond-mat.stat-mech | null | The classical behaviour of a macroscopic system consisting of a large number
of microscopic systems is derived in the framework of the Bohmian
interpretation of quantum mechanics. Under appropriate assumptions concerning
the localization and factorization of the wavefunction it is shown explicitly
that the center of mass motion of the system is determined by the classical
equations of motion.
| [
{
"version": "v1",
"created": "Tue, 22 Jun 1999 19:56:25 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Geiger",
"H.",
""
],
[
"Obermair",
"G.",
""
],
[
"Helm",
"Ch.",
""
]
] |
quant-ph/9906083 | T. Hakioglu | T. Hakioglu | Linear canonical transformations and quantum phase:a unified canonical
and algebraic approach | 19 pages, no figures | J.Phys.A32:4111-4130,1999 | 10.1088/0305-4470/32/22/312 | null | quant-ph | null | The algebra of generalized linear quantum canonical transformations is
examined in the prespective of Schwinger's unitary-canonical basis. Formulation
of the quantum phase problem within the theory of quantum canonical
transformations and in particular with the generalized quantum action-angle
phase space formalism is established and it is shown that the conceptual
foundation of the quantum phase problem lies within the algebraic properties of
the quantum canonical transformations in the quantum phase space. The
representations of the Wigner function in the generalized action-angle unitary
operator pair for certain Hamiltonian systems with the dynamical symmetry are
examined. This generalized canonical formalism is applied to the quantum
harmonic oscillator to examine the properties of the unitary quantum phase
operator as well as the action-angle Wigner function.
| [
{
"version": "v1",
"created": "Wed, 23 Jun 1999 11:58:20 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hakioglu",
"T.",
""
]
] |
quant-ph/9906084 | Tomoyuki Yamakami | Tomoyuki Yamakami | A Foundation of Programming a Multi-Tape Quantum Turing machine | A twelve page version is to appear in the Proceedings of the 24th
International Symposium on Mathematical Foundations of Computer Science in
September, 1999. LNCS | null | null | null | quant-ph cs.CC | null | The notion of quantum Turing machines is a basis of quantum complexity
theory. We discuss a general model of multi-tape, multi-head Quantum Turing
machines with multi final states that also allow tape heads to stay still.
| [
{
"version": "v1",
"created": "Wed, 23 Jun 1999 15:17:21 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Yamakami",
"Tomoyuki",
""
]
] |
quant-ph/9906085 | Dorje C. Brody | D.C. Brody (DAMTP) and L.P. Hughston (King's College London) | Information Content for Quantum States | RevTex file, 4 pages, 1 fig | J.Math.Phys. 41 (2000) 2586-2592 | 10.1063/1.533260 | null | quant-ph | null | A method of representing probabilistic aspects of quantum systems is
introduced by means of a density function on the space of pure quantum states.
In particular, a maximum entropy argument allows us to obtain a natural density
function that only reflects the information provided by the density matrix.
This result is applied to derive the Shannon entropy of a quantum state. The
information theoretic quantum entropy thereby obtained is shown to have the
desired concavity property, and to differ from the the conventional von Neumann
entropy. This is illustrated explicitly for a two-state system.
| [
{
"version": "v1",
"created": "Wed, 23 Jun 1999 15:40:45 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Brody",
"D. C.",
"",
"DAMTP"
],
[
"Hughston",
"L. P.",
"",
"King's College London"
]
] |
quant-ph/9906086 | Dorje C. Brody | Dorje C. Brody (Imperial), Lane P. Hughston (King's) | Geometric Quantum Mechanics | 27 pages. Extended with additional material | J.Geom.Phys. 38 (2001) 19-53 | 10.1016/S0393-0440(00)00052-8 | null | quant-ph | null | The manifold of pure quantum states is a complex projective space endowed
with the unitary-invariant geometry of Fubini and Study. According to the
principles of geometric quantum mechanics, the detailed physical
characteristics of a given quantum system can be represented by specific
geometrical features that are selected and preferentially identified in this
complex manifold. Here we construct a number of examples of such geometrical
features as they arise in the state spaces for spin-1/2, spin-1, and spin-3/2
systems, and for pairs of spin-1/2 systems. A study is undertaken on the
geometry of entangled states, and a natural measure is assigned to the degree
of entanglement of a given state for a general multi-particle system. The
properties of this measure are analysed for the entangled states of a pair of
spin-1/2 particles. With the specification of a quantum Hamiltonian, the
resulting Schrodinger trajectory induces a Killing field, which is quasiergodic
on a toroidal subspace of the energy surface. When the dynamical trajectory is
lifted orthogonally to Hilbert space, it induces a geometric phase shift on the
wave function. The uncertainty of an observable in a given state is the length
of the gradient vector of the level surface of the expectation of the
observable in that state, a fact that allows us to calculate higher order
corrections to the Heisenberg relations. A general mixed state is determined by
a probability density function on the state space, for which the associated
first moment is the density matrix. The advantage of a general state is in its
applicability in various attempts to go beyond the standard quantum theory.
| [
{
"version": "v1",
"created": "Wed, 23 Jun 1999 16:19:42 GMT"
},
{
"version": "v2",
"created": "Fri, 15 Oct 1999 10:29:53 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Brody",
"Dorje C.",
"",
"Imperial"
],
[
"Hughston",
"Lane P.",
"",
"King's"
]
] |
quant-ph/9906087 | Jesse Hersch | J. S. Hersch, M. R. Haggerty, E. J. Heller | Diffractive orbits in an open microwave billiard | 6 figures, submitted to PRL | Phys.Rev.Lett. 83 (1999) 5342-5345 | 10.1103/PhysRevLett.83.5342 | null | quant-ph | null | We demonstrate the existence and significance of diffractive orbits in an
open microwave billiard, both experimentally and theoretically. Orbits that
diffract off of a sharp edge strongly influence the conduction spectrum of this
resonator, especially in the regime where there are no stable classical orbits.
On resonance, the wavefunctions are influenced by both classical and
diffractive orbits. Off resonance, the wavefunctions are determined by the
constructive interference of multiple transient, nonperiodic orbits.
Experimental, numerical, and semiclassical results are presented.
| [
{
"version": "v1",
"created": "Wed, 23 Jun 1999 17:59:42 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Hersch",
"J. S.",
""
],
[
"Haggerty",
"M. R.",
""
],
[
"Heller",
"E. J.",
""
]
] |
quant-ph/9906088 | Pierre Meystre | E. V. Goldstein, M. G. Moore and P. Meystre | Nonlinear manipulation and control of matter waves | Proceedings of LPHYS'99, Budapest, to be published in Laser Physics | null | null | null | quant-ph cond-mat.soft physics.atom-ph | null | This paper reviews some of our recent results in nonlinear atom optics. In
addition to nonlinear wave-mixing between matter waves, we also discuss the
dynamical interplay between optical and matter waves. This new paradigm, which
is now within experimental reach, has the potential to impact a number of
fields of physics, including the manipulation and applications of atomic
coherence, and the preparation of quantum entanglement between microscopic and
macroscopic systems. Possible applications include quantum information
processing, matter-wave holography, and nanofabrication.
| [
{
"version": "v1",
"created": "Wed, 23 Jun 1999 21:47:18 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Goldstein",
"E. V.",
""
],
[
"Moore",
"M. G.",
""
],
[
"Meystre",
"P.",
""
]
] |
quant-ph/9906089 | S. G. Schirmer | S. G. Schirmer, M. D. Girardeau, J. V. Leahy | Efficient Algorithm for Optimal Control of Mixed-State Quantum Systems | 8 pages, revised edition, improved content and figures | Phys.Rev. A61 (2000) 012101 | 10.1103/PhysRevA.61.012101 | null | quant-ph | null | In [1] Zhu and Rabitz presented a rapidly convergent iterative algorithm for
optimal control of the expectation value of a positive definite observable in a
pure-state quantum system. In this paper we generalize this algorithm to a
quantum statistical mechanics setting and show that it is both efficient in the
mixed-state case and effective in achieving the control objective of maximizing
the ensemble average of arbitrary observables in the cases studied.
| [
{
"version": "v1",
"created": "Thu, 24 Jun 1999 02:37:41 GMT"
},
{
"version": "v2",
"created": "Thu, 16 Sep 1999 21:59:23 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Schirmer",
"S. G.",
""
],
[
"Girardeau",
"M. D.",
""
],
[
"Leahy",
"J. V.",
""
]
] |
quant-ph/9906090 | Tomohiro Ogawa | Tomohiro Ogawa, Hiroshi Nagaoka | Strong Converse and Stein's Lemma in the Quantum Hypothesis Testing | LaTeX, 12 pages, submitted to IEEE Trans. Inform. Theory | null | 10.1142/9789812563071_0003 | null | quant-ph | null | The hypothesis testing problem of two quantum states is treated. We show a
new inequality between the error of the first kind and the second kind, which
complements the result of Hiai and Petz to establish the quantum version of
Stein's lemma. The inequality is also used to show a bound on the first kind
error when the power exponent for the second kind error exceeds the quantum
relative entropy, and the bound yields the strong converse in the quantum
hypothesis testing. Finally, we discuss the relation between the bound and the
power exponent derived by Han and Kobayashi in the classical hypothesis
testing.
| [
{
"version": "v1",
"created": "Thu, 24 Jun 1999 08:22:59 GMT"
}
] | 2016-11-18T00:00:00 | [
[
"Ogawa",
"Tomohiro",
""
],
[
"Nagaoka",
"Hiroshi",
""
]
] |
quant-ph/9906091 | Dr. V. Krasnoholovets | Volodymyr Krasnoholovets (Institute of Physics, Kyiv, Ukraine) | On the theory of the anomalous photoelectric effect stemming from a
substructure of matter waves | 20 pages, no figures, LaTeX 2e, the journal version | Indian Journal of Theoretical Physics, vol. 49, no. 1, pp. 1-32
(2001) | null | null | quant-ph physics.atom-ph | null | The two opposite concepts - multiphoton and effective photon - readily
describing the photoelectric effect under strong irradiation in the case that
the energy of the incident light is essentially smaller than the ionisation
potential of gas atoms and the work function of the metal are treated. Based on
the submicroscopic construction of quantum mechanics developed in the previous
papers by the author [Phys. Essays vol. 6, 554 (1993); vol. 10, 407 (1997)] the
analysis of the reasons of the two concepts discrepancies is led. Taking into
account the main hypothesis of those works, i.e., that the electron is an
extended object that is not point-like, the study of the interaction between
the electron and a photon flux is carried out in detail. A comparison with
numerous experiments is performed.
| [
{
"version": "v1",
"created": "Thu, 24 Jun 1999 14:53:10 GMT"
},
{
"version": "v2",
"created": "Thu, 28 Oct 1999 06:12:22 GMT"
},
{
"version": "v3",
"created": "Tue, 14 Aug 2001 13:13:48 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Krasnoholovets",
"Volodymyr",
"",
"Institute of Physics, Kyiv, Ukraine"
]
] |
quant-ph/9906092 | Kurt Jacobs | Tanmoy Bhattacharya, Salman Habib, Kurt Jacobs | Continuous Quantum Measurement and the Emergence of Classical Chaos | 5 pages, multicol revtex | Phys.Rev.Lett.85:4852-4855,2000 | 10.1103/PhysRevLett.85.4852 | LA-UR-99-3187 | quant-ph | null | We formulate the conditions under which the dynamics of a continuously
measured quantum system becomes indistinguishable from that of the
corresponding classical system. In particular, we demonstrate that even in a
classically chaotic system the quantum state vector conditioned by the
measurement remains localized and, under these conditions, follows a trajectory
characterized by the classical Lyapunov exponent.
| [
{
"version": "v1",
"created": "Thu, 24 Jun 1999 16:40:14 GMT"
},
{
"version": "v2",
"created": "Thu, 13 Jul 2000 22:18:52 GMT"
}
] | 2009-01-23T00:00:00 | [
[
"Bhattacharya",
"Tanmoy",
""
],
[
"Habib",
"Salman",
""
],
[
"Jacobs",
"Kurt",
""
]
] |
quant-ph/9906093 | Dimitris G. Angelakis | E. Paspalakis, D.G. Angelakis and P.L. Knight | The influence of density of modes on dark lines in spontaneous emission | 11 pages including 9 figures | Opt.Commun. 172 (1999) 229 | 10.1016/S0030-4018(99)00511-8 | null | quant-ph | null | We study two distinct multi-level atomic models in which one transition is
coupled to a Markovian reservoir, while another linked transition is coupled to
a non-Markovian reservoir. We show that by choosing appropriately the density
of modes of the non-Markovian reservoir the spontaneous emission to the
Markovian reservoir is greatly altered. The existence of `dark lines' in the
spontaneous emission spectrum in the Markovian reservoir due to the coupling to
specific density of modes of the non-Markovian reservoir is also predicted.
| [
{
"version": "v1",
"created": "Thu, 24 Jun 1999 16:52:35 GMT"
},
{
"version": "v2",
"created": "Mon, 27 Sep 1999 17:25:12 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Paspalakis",
"E.",
""
],
[
"Angelakis",
"D. G.",
""
],
[
"Knight",
"P. L.",
""
]
] |
quant-ph/9906094 | Lorenza Viola | Lorenza Viola, Seth Lloyd, and Emanuel Knill | Universal Control of Decoupled Quantum Systems | 4 pages, no figures; REVTeX style | Phys.Rev.Lett.83:4888-4891,1999 | 10.1103/PhysRevLett.83.4888 | null | quant-ph | null | It is shown that if one can perform a restricted set of fast manipulations on
a quantum system, one can implement a large class of dynamical evolutions by
effectively removing or introducing selected Hamiltonians. The procedure can be
used to achieve universal noise-tolerant control based on purely unitary
open-loop transformations of the dynamics. As a result, it is in principle
possible to perform noise-protected universal quantum computation using no
extra space resources.
| [
{
"version": "v1",
"created": "Thu, 24 Jun 1999 19:16:29 GMT"
}
] | 2009-01-23T00:00:00 | [
[
"Viola",
"Lorenza",
""
],
[
"Lloyd",
"Seth",
""
],
[
"Knill",
"Emanuel",
""
]
] |
quant-ph/9906095 | Masanao Ozawa | Harumichi Nishimura and Masanao Ozawa (Nagoya University) | Computational Complexity of Uniform Quantum Circuit Families and Quantum
Turing Machines | 34 pages, LaTeX, revised and extended, to appear in Theoret. Comput.
Sci | Theor.Comput.Sci. 276 (2002) 147-181 | null | null | quant-ph | null | Deutsch proposed two sorts of models of quantum computers, quantum Turing
machines (QTMs) and quantum circuit families (QCFs). In this paper we explore
the computational powers of these models and re-examine the claim of the
computational equivalence of these models often made in the literature without
detailed investigations. For this purpose, we formulate the notion of the codes
of QCFs and the uniformity of QCFs by the computability of the codes. Various
complexity classes are introduced for QTMs and QCFs according to constraints on
the error probability of algorithms or transition amplitudes. Their
interrelations are examined in detail. For Monte Carlo algorithms, it is proved
that the complexity classes based on uniform QCFs are identical with the
corresponding classes based on QTMs. However, for Las Vegas algorithms, it is
still open whether the two models are equivalent. We indicate the possibility
that they are not equivalent. In addition, we give a complete proof of the
existence of a universal QTM simulating multi-tape QTMs efficiently. We also
examine the simulation of various types of QTMs such as multi-tape QTMs, single
tape QTMs, stationary, normal form QTMs (SNQTMs), and QTMs with the binary
tapes. As a result, we show that these QTMs are computationally equivalent one
another as computing models implementing not only Monte Carlo algorithms but
exact (or error-free) ones.
| [
{
"version": "v1",
"created": "Fri, 25 Jun 1999 10:52:21 GMT"
},
{
"version": "v2",
"created": "Fri, 2 Jul 1999 10:04:32 GMT"
},
{
"version": "v3",
"created": "Tue, 26 Dec 2000 16:00:33 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Nishimura",
"Harumichi",
"",
"Nagoya University"
],
[
"Ozawa",
"Masanao",
"",
"Nagoya University"
]
] |
quant-ph/9906096 | Gregg Jaeger | Gregg Jaeger (Boston University, Dept. of Elect. and Comp. Eng. and
Starlab nv) | Book Review: Bohmian Mechanics and Quantum Theory: An Appraisal | 4 pages as plain text, no figures. (Reason for new version: typos in
abstract corrected.) To appear in Studies in History and Philosophy of Modern
Physics | null | null | null | quant-ph | null | A review of "Bohmian Mechanics and Quantum Theory: An Appraisal" (James
Cushing, Arthur Fine and Sheldon Goldstein, Eds.), an extensive collection of
articles on Bohmian mechanics. In addition to broad, critical overviews of
Bohmian mechanics, the reviewed collection contains extensions and hybrid
versions of the theory and several detailed applications to practical
situtations.
| [
{
"version": "v1",
"created": "Fri, 25 Jun 1999 11:31:06 GMT"
},
{
"version": "v2",
"created": "Tue, 29 Jun 1999 14:32:24 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Jaeger",
"Gregg",
"",
"Boston University, Dept. of Elect. and Comp. Eng. and\n Starlab nv"
]
] |
quant-ph/9906097 | Ian C. Percival | Ian C. Percival | Quantum state diffusion, measurement and second quantization | 10 pages | Phys.Lett. A261 (1999) 134-138 | 10.1016/S0375-9601(99)00526-5 | QMW-TH-99 | quant-ph | null | Realistic dynamical theories of measurement based on the diffusion of quantum
states are nonunitary, whereas quantum field theory and its generalizations are
unitary. This problem in the quantum field theory of quantum state diffusion
(QSD) appears already in the Lagrangian formulation of QSD as a classical
equation of motion, where Liouville's theorem does not apply to the usual field
theory formulation. This problem is resolved here by doubling the number of
freedoms used to represent a quantum field. The space of quantum fields is then
a classical configuration space, for which volume need not be conserved,
instead of the usual phase space, to which Liouville's theorem applies. The
creation operator for the quantized field satisfies the QSD equations, but the
annihilation operator does not satisfy the conjugate eqation. It appears only
in a formal role.
| [
{
"version": "v1",
"created": "Fri, 25 Jun 1999 11:22:14 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Percival",
"Ian C.",
""
]
] |
quant-ph/9906098 | Stephen Parker | S. Parker, S. Bose, M.B. Plenio | Entanglement quantification and purification in continuous variable
systems | 8 pages revtex | Phys.Rev. A61 (2000) 32305 | 10.1103/PhysRevA.61.032305 | null | quant-ph | null | We develop theoretical and numerical tools for the quantification of
entanglement in systems with continuous degrees of freedom. Continuous variable
entanglement swapping is introduced and based on this idea we develop methods
of entanglement purification for continuous variable systems. The success of
these entanglement purification methods is then assessed using these tools.
| [
{
"version": "v1",
"created": "Fri, 25 Jun 1999 14:43:16 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Parker",
"S.",
""
],
[
"Bose",
"S.",
""
],
[
"Plenio",
"M. B.",
""
]
] |
quant-ph/9906099 | Stefan Weigert | Jean-Pierre Amiet and Stefan Weigert | Discrete Q- and P-symbols for spin s | 6 pages, Latex2e | J.Opt. B2 (2000) 118 | 10.1088/1464-4266/2/2/309 | null | quant-ph | null | Non-orthogonal bases of projectors on coherent states are introduced to
expand hermitean operators acting on the Hilbert space of a spin s. It is shown
that the expectation values of a hermitean operator A in a family of
(2s+1)(2s+1) spin-coherent states determine the operator unambiguously. In
other words, knowing the Q-symbol of A at (2s+1)(2s+1) points on the unit
sphere is already sufficient in order to recover the operator. This provides a
straightforward method to reconstruct the mixed state of a spin since its
density matrix is explicitly parametrized in terms of expectation values.
Furthermore, a discrete P-symbol emerges naturally which is related to a basis
dual to the original one.
| [
{
"version": "v1",
"created": "Sat, 26 Jun 1999 11:56:21 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Amiet",
"Jean-Pierre",
""
],
[
"Weigert",
"Stefan",
""
]
] |
quant-ph/9906100 | Masao Matsumoto | Masao Matsumoto | SU(2) coherent state path integrals based on arbitrary fiducial vectors
and geometric phases | 13 pages, no figures, LaTeX2.09 with ioplppt stylefile. The main
stream is the same as that of the previous one. However, the whole manuscript
is rewritten so that it does not include the incorrect reasoning in Euler
angles in Appendix B of the previous version. Thus the present results are
represented in terms of a full set of three Euler angles. Some other minor
corrections are also made; Besides the title has also changed; The previous
one is: A new form of SU(2) coherent state path integrals based on arbitrary
starting vectors | null | null | null | quant-ph | null | We develop the formulation of the spin(SU(2)) coherent state path integrals
based on arbitrary fiducial vectors. The resultant action in the path integral
expression extensively depends on the vector; It differs from the conventional
one in that it has a generalized form having some additional terms. We also
study, as physical applications, the geometric phases associated with the
coherent state path integrals to find that new effects of the terms may appear
in experiments. We see that the formalism gives a clear insight into geometric
phases.
| [
{
"version": "v1",
"created": "Sat, 26 Jun 1999 13:45:04 GMT"
},
{
"version": "v2",
"created": "Mon, 22 Nov 1999 11:20:02 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Matsumoto",
"Masao",
""
]
] |
quant-ph/9906101 | Mladen Pavicic | Mladen Pavicic and Norman D. Megill | Non-Orthomodular Models for Both Quantum Logic and Standard Classical
Logic: Repercussions for Quantum Computers | 21 pages, AMSLaTeX, to be published in Helvetica Physica Acta, a few
typos corrected, Author's URL http://m3k.grad.hr/pavicic | Helv.Phys.Acta 72 (1999) 189-210 | null | null | quant-ph math.LO math.QA | null | It is shown that propositional calculuses of both quantum and classical
logics are non-categorical. We find that quantum logic is in addition to an
orthomodular lattice also modeled by a weakly orthomodular lattice and that
classical logic is in addition to a Boolean algebra also modeled by a weakly
distributive lattice. Both new models turn out to be non-orthomodular. We prove
the soundness and completeness of the calculuses for the models. We also prove
that all the operations in an orthomodular lattice are five-fold defined. In
the end we discuss possible repercussions of our results to quantum
computations and quantum computers.
| [
{
"version": "v1",
"created": "Sun, 27 Jun 1999 14:55:18 GMT"
},
{
"version": "v2",
"created": "Tue, 29 Jun 1999 10:11:13 GMT"
},
{
"version": "v3",
"created": "Sun, 12 Sep 1999 21:49:37 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Pavicic",
"Mladen",
""
],
[
"Megill",
"Norman D.",
""
]
] |
quant-ph/9906102 | Mladen Pavicic | Harry Paul and Mladen Pavicic | Realistic Interaction-Free Detection of Objects in a Resonator | 12 pages, LaTeX, 6 ps figures, Author's URL
http://m3k.grad.hr/pavicic | Found.Phys. 28 (1998) 959-970 | null | null | quant-ph | null | We propose a realistic device for detecting objects almost without
transferring a single quantum of energy to them. The device can work with an
efficiency close to 100% and relies on two detectors counting both presence and
absence of the objects. Its possible usage in performing fundamental
experiments as well as possible applications are discussed.
| [
{
"version": "v1",
"created": "Sun, 27 Jun 1999 15:33:55 GMT"
},
{
"version": "v2",
"created": "Sun, 12 Sep 1999 21:36:17 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Paul",
"Harry",
""
],
[
"Pavicic",
"Mladen",
""
]
] |
quant-ph/9906103 | Adrian Kent | Adrian Kent (Centre for Quantum Computation, University of Cambridge) | Secure Classical Bit Commitment using Fixed Capacity Communication
Channels | Proofs of classical security simplified and extended. Precise
estimates for practical implementation, showing near perfect security
attainable for separations of 10 km. New definitions of successful unveiling
and of effective commitment in a redundant bit commitment scheme. New
discussion of the deniability of relativistic bit commitments and (a point
due to Mueller-Quade and Unruh) their retractability. 32 pages, revtex
preprint format. Erratum on p329 of published version corrected | J.Cryptolog. 18 (2005) 313-335 | null | DAMTP-1999-47 | quant-ph cs.CR | null | If mutually mistrustful parties A and B control two or more appropriately
located sites, special relativity can be used to guarantee that a pair of
messages exchanged by A and B are independent. In earlier work, we used this
fact to define a relativistic bit commitment protocol, RBC1, in which security
is maintained by exchanging a sequence of messages whose transmission rate
increases exponentially in time. We define here a new relativistic protocol,
RBC2, which requires only a constant transmission rate and could be practically
implemented. We prove that RBC2 allows a bit commitment to be indefinitely
maintained with unconditional security against all classical attacks. We
examine its security against quantum attacks, and show that it is immune from
the class of attacks shown by Mayers and Lo-Chau to render non-relativistic
quantum bit commitment protocols insecure.
| [
{
"version": "v1",
"created": "Mon, 28 Jun 1999 14:35:30 GMT"
},
{
"version": "v2",
"created": "Thu, 7 Nov 2002 09:06:39 GMT"
},
{
"version": "v3",
"created": "Tue, 3 Dec 2002 23:27:08 GMT"
},
{
"version": "v4",
"created": "Thu, 12 Dec 2002 23:45:21 GMT"
},
{
"version": "v5",
"created": "Mon, 2 Aug 2004 12:55:02 GMT"
},
{
"version": "v6",
"created": "Wed, 2 Mar 2005 16:37:08 GMT"
},
{
"version": "v7",
"created": "Mon, 2 Oct 2006 20:09:36 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kent",
"Adrian",
"",
"Centre for Quantum Computation, University of Cambridge"
]
] |
quant-ph/9906104 | Marat | V.A.Skrebnev and M.N.Ovchinnikov | Metrical Separability of the Spin Systems Energetic Surfaces and Quantum
Jumps Hypothesis | 8 pages, 1 figure EPS | null | null | null | quant-ph | null | Metrical separability of the spin systems energetic surfaces is shown. The
irreversibility of the spin system evolution is considered as the consequence
of random quantum jumps on energy surfaces.
| [
{
"version": "v1",
"created": "Mon, 28 Jun 1999 09:32:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Skrebnev",
"V. A.",
""
],
[
"Ovchinnikov",
"M. N.",
""
]
] |
quant-ph/9906105 | Nicolas J. Cerf | N. J. Cerf (1), N. Gisin (2), S. Massar (1) ((1) U. Brussels, (2) U.
Geneva) | Classical Teleportation of a Quantum Bit | 4 pages, RevTex | Phys.Rev.Lett.84:2521,2000 | 10.1103/PhysRevLett.84.2521 | ULB-TH/99-11 | quant-ph | null | Classical teleportation is defined as a scenario where the sender is given
the classical description of an arbitrary quantum state while the receiver
simulates any measurement on it. This scenario is shown to be achievable by
transmitting only a few classical bits if the sender and receiver initially
share local hidden variables. Specifically, a communication of 2.19 bits is
sufficient on average for the classical teleportation of a qubit, when
restricted to von Neumann measurements. The generalization to
positive-operator-valued measurements is also discussed.
| [
{
"version": "v1",
"created": "Mon, 28 Jun 1999 09:47:22 GMT"
}
] | 2009-01-23T00:00:00 | [
[
"Cerf",
"N. J.",
""
],
[
"Gisin",
"N.",
""
],
[
"Massar",
"S.",
""
]
] |
quant-ph/9906106 | Molotkov S. | S.N.Molotkov and S.S.Nazin (Institute of Solid State Physics, Russian
Academy of Sciences) | Single Spin State Detection for the Kane Model of Silicon-Based Quantum
Computer | 6 pages, 2 figures | null | null | null | quant-ph | null | The scheme for measurement of the state of a single spin (or a few spin
system) based on the single-electron turnstile and injection of spin polarized
electrons from magnetic metal contacts is proposed. Applications to the recent
proposal concerning the spin gates based on a silicon matrix (B.Kane, Nature,
{\bf 393}, 133 (1998)) are discussed.
| [
{
"version": "v1",
"created": "Mon, 28 Jun 1999 12:17:39 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Molotkov",
"S. N.",
"",
"Institute of Solid State Physics, Russian\n Academy of Sciences"
],
[
"Nazin",
"S. S.",
"",
"Institute of Solid State Physics, Russian\n Academy of Sciences"
]
] |
quant-ph/9906107 | Michael J. W. Hall | Michael J. W. Hall, Martina S. Reineker and Wolfgang P. Schleich | Unravelling quantum carpets: a travelling wave approach | Latex, 26 pages + 6 figures, submitted to J. Phys. A (connections
with prior literature clarified) | J.Phys.A32:8275-8291,1999 | 10.1088/0305-4470/32/47/307 | null | quant-ph physics.optics | null | Quantum carpets are generic spacetime patterns formed in the probability
distributions P(x,t) of one-dimensional quantum particles, first discovered in
1995. For the case of an infinite square well potential, these patterns are
shown to have a detailed quantitative explanation in terms of a travelling-wave
decomposition of P(x,t). Each wave directly yields the time-averaged structure
of P(x,t) along the (quantised)spacetime direction in which the wave
propagates. The decomposition leads to new predictions of locations, widths
depths and shapes of carpet structures, and results are also applicable to
light diffracted by a periodic grating and to the quantum rotator. A simple
connection between the waves and the Wigner function of the initial state of
the particle is demonstrated, and some results for more general potentials are
given.
| [
{
"version": "v1",
"created": "Mon, 28 Jun 1999 12:19:03 GMT"
},
{
"version": "v2",
"created": "Sun, 8 Aug 1999 08:05:08 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hall",
"Michael J. W.",
""
],
[
"Reineker",
"Martina S.",
""
],
[
"Schleich",
"Wolfgang P.",
""
]
] |
quant-ph/9906108 | Domenico Giulini | Domenico Giulini | States, Symmetries and Superselection | 14 pages, LaTeX2e, Springer-Macro cl2emult.cls. To appear in:
"Decoherence: Theoretical, Experimental, and Conceptual Problems", Eds. P.
Blanchard, D. Giulini, E. Joos, C. Kiefer, and I-O. Stamatescu, Springer
Lecture Notes in Physics 1999 | Lect.Notes Phys. 538 (2000) 87-100 | null | ZU-TH 17/99 | quant-ph gr-qc hep-th | null | The process of dynamical decoherence may cause apparent superselection rules,
which are sometimes called `environmentally induced' or `soft'. A natural
question is whether such dynamical processes are eventually also responsible
for at least some of the superselection rules which are usually presented as
fundamentally rooted in the kinematical structure of the theory (so called
`hard' superselection rules). With this question in mind, I re-investigate two
well known examples where superselection rules are usually argued to rigorously
exist within the given mathematical framework. These are (1) the Bargmann
superselection rule for the total mass in Galilei invariant quantum mechanics
and (2) the charge superselection rule in quantum electrodynamics. I argue
that, for various reasons, the kinematical arguments usually given are not
physically convincing unless they are based on an underlying dynamical process.
| [
{
"version": "v1",
"created": "Mon, 28 Jun 1999 14:07:06 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Giulini",
"Domenico",
""
]
] |
quant-ph/9906109 | Gustavo Lopez-Velazquez | G.P. Berman, A.R. Bishop, G.D. Doolen, G.V. Lopez, and V.I.
Tsifrinovich | Influence of Non-Resonant Effects on the Dynamics of Quantum Logic Gates
at Room Temperature | 14 pages, 7 postscript figures | null | null | null | quant-ph | null | We study numerically the influence of non-resonant effects on the dynamics of
a single $\pi$-pulse quantum CONTROL-NOT (CN) gate in a macroscopic ensemble of
fo ur-spin molecules at room temperature. The four nuclear spins in each
molecule r epresent a four-qubit register. The qubits are ``labeled'' by the
characteristic frequencies, $\omega_k$, ($k=0$ to 3) due to the Zeeman
interaction of the nuclear spins with the magnetic field. The qubits interact
with each other through an Ising interaction of strength $J$. T he paper
examines the feasibility of implementing a single-pulse quantum CN gate in an
ensemble of quantum molecules at room temperature. We determine a paramet er
region, $\omega_k$ and $J$, in which a single-pulse quantum CN gate can be i
mplemented at room temperature. We also show that there exist characteristic
cri tical values of parameters,
$\Delta\omega_{cr}\equiv|\omega_{k^\prime}-\omega_k|_{cr}$ and $J_{cr}$, such
that for $J<J_{cr}$ and
$\Delta\omega_k\equiv|\omega_{k^\prime}-\omega_k|<\Delta\omega_{cr}$,
non-resonant effects are sufficient to d estroy the dynamics required for
quantum logic operations.
| [
{
"version": "v1",
"created": "Mon, 28 Jun 1999 19:57:27 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Berman",
"G. P.",
""
],
[
"Bishop",
"A. R.",
""
],
[
"Doolen",
"G. D.",
""
],
[
"Lopez",
"G. V.",
""
],
[
"Tsifrinovich",
"V. I.",
""
]
] |
quant-ph/9906110 | Valery N. Gorbachev | V.N.Gorbachev and A.I.Trubilko | Quantum teleportation of EPR pair by three-particle entanglement | 7 pages, LaTeX, 3 figures | J.Exp.Theor.Phys. 91 (2000) 894-898; Zh.Eksp.Teor.Fiz. 91 (2000)
1036-1040 | 10.1134/1.1334979 | null | quant-ph | null | Teleportation of an EPR pair using triplet in state of the
Horne-Greenberger-Zeilinger form to two receivers is considered. It needs a
three-particle basis for joint measurement. By contrast the one qubit
teleportation the required basis is not maximally entangled. It consists of the
states corresponding to the maximally entanglement of two particles only. Using
outcomes of measurement both receivers can recover an unknown EPR state however
one of them can not do it separately. Teleportation of the N-particle
entanglement is discussed.
| [
{
"version": "v1",
"created": "Mon, 28 Jun 1999 20:36:22 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Gorbachev",
"V. N.",
""
],
[
"Trubilko",
"A. I.",
""
]
] |
quant-ph/9906111 | Richard Cleve | Richard Cleve (U of Calgary) | An Introduction to Quantum Complexity Theory | 28 pages, LaTeX, 11 figures within the text, to appear in "Collected
Papers on Quantum Computation and Quantum Information Theory", edited by C.
Macchiavello, G.M. Palma, and A. Zeilinger (World Scientific) | null | 10.1142/9789810248185_0004 | null | quant-ph | null | We give a basic overview of computational complexity, query complexity, and
communication complexity, with quantum information incorporated into each of
these scenarios. The aim is to provide simple but clear definitions, and to
highlight the interplay between the three scenarios and currently-known quantum
algorithms.
| [
{
"version": "v1",
"created": "Mon, 28 Jun 1999 21:52:49 GMT"
}
] | 2016-11-23T00:00:00 | [
[
"Cleve",
"Richard",
"",
"U of Calgary"
]
] |
quant-ph/9906112 | Xinlan Zhou | Xinlan Zhou (1,2), Debbie W. Leung (1,2) and Isaac L. Chuang (2) ((1)
Stanford University (2) IBM Almaden Research Center) | Quantum algorithms which accept hot qubit inputs | 4 pages, revtex, submitted June 29, 1999 | null | null | null | quant-ph | null | Realistic physical implementations of quantum computers can entail tradeoffs
which depart from the ideal model of quantum computation. Although these
tradeoffs have allowed successful demonstration of certain quantum algorithms,
a crucial question is whether they fundamentally limit the computational
capacity of such machines. We study the limitations of a quantum computation
model in which only ensemble averages of measurement observables are
accessible. Furthermore, we stipulate that input qubits may only be prepared in
highly random, ``hot'' mixed states. In general, these limitations are believed
to dramatically detract from the computational power of the system. However, we
construct a class of algorithms for this limited model, which, surprisingly,
are polynomially equivalent to the ideal case. This class includes the well
known Deutsch-Jozsa algorithm.
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 04:57:29 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Zhou",
"Xinlan",
""
],
[
"Leung",
"Debbie W.",
""
],
[
"Chuang",
"Isaac L.",
""
]
] |
quant-ph/9906113 | Gaosan | Gao Shan | Quantum superluminal communication does not result in the causal loop | 2 pages, no figures, please refer to physics/9907001, physics/9907002
and physics/9907005 | null | null | IQMC-99-05-GSNC | quant-ph | null | We show that the quantum superluminal communication based on the quantum
nonlocal influence, if exists, will not result in the causal loop, this
conclusion is essentially determined by the peculiarity of the quantum nonlocal
influence itself, according to which there must exist a preferred Lorentz frame
for consistently describing the quantum nonlocal process.
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 07:41:58 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Jul 1999 00:50:37 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Shan",
"Gao",
""
]
] |
quant-ph/9906114 | Mary Beth Ruskai | Mary Beth Ruskai | Pauli Exchange Errors in Quantum Computation | Final version accepted for publication in Phys. Rev. Lett | Phys.Rev.Lett.85:194-197,2000 | 10.1103/PhysRevLett.85.194 | null | quant-ph math-ph math.MP | null | In many physically realistic models of quantum computation, Pauli exchange
interactions cause a subset of two-qubit errors to occur as a first order
effect of couplings within the computer, even in the absence of interactions
with the computer's environment. We give an explicit 9-qubit code that corrects
both Pauli exchange errors and all one-qubit errors.
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 08:19:30 GMT"
},
{
"version": "v2",
"created": "Tue, 24 Aug 1999 18:22:14 GMT"
},
{
"version": "v3",
"created": "Tue, 28 Dec 1999 05:48:36 GMT"
},
{
"version": "v4",
"created": "Thu, 1 Jun 2000 13:19:10 GMT"
}
] | 2009-01-23T00:00:00 | [
[
"Ruskai",
"Mary Beth",
""
]
] |
quant-ph/9906115 | David Vitali | Rodolfo Bonifacio, Stefano Olivares, Paolo Tombesi and David Vitali | Non dissipative decoherence of Rabi oscillations | 4 pages, RevTeX | null | 10.1080/09500340008235142 | null | quant-ph | null | We present a simple theoretical description of two recent experiments where
damping of Rabi oscillations, which cannot be attributed to dissipative
decoherence, has been observed. This is obtained considering the evolution time
or the Hamiltonian as random variables and then averaging the usual unitary
evolution on a properly defined, model-independent, probability distribution.
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 17:45:00 GMT"
},
{
"version": "v2",
"created": "Sun, 4 Jul 1999 15:18:51 GMT"
},
{
"version": "v3",
"created": "Mon, 25 Oct 1999 13:46:35 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Bonifacio",
"Rodolfo",
""
],
[
"Olivares",
"Stefano",
""
],
[
"Tombesi",
"Paolo",
""
],
[
"Vitali",
"David",
""
]
] |
quant-ph/9906116 | Gaoshan | Gao Shan | How to realize quantum superluminal communication? | 5 pages, no figures, please refer to physics/9907001, physics/9907002
and physics/9907005 | null | null | IQMC-99-06-GS3 | quant-ph | null | We deeply analyze the possibility to achieve quantum superluminal
communication beyond the domain of special relativity and present quantum
theory, and show that when using the conscious object as one part of the
measuring device, quantum superluminal communication may be a natural thing.
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 09:17:24 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Jul 1999 00:40:53 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Shan",
"Gao",
""
]
] |
quant-ph/9906117 | George Svetlichny | George Svetlichny | Non-linear Schroedinger Equations, Separation and Symmetry | LaTeX, 31 pages | J.Nonlin.Math.Phys. 2 (1995) 2-26 | null | null | quant-ph | null | We investigate the symmetry properties of hierarchies of non-linear
Schroedinger equations (introduced by Doebner and Goldin, and Goldin and
Svetlichny), which describe non-interacting systems in which tensor product
wave-functions evolve by independent evolution of the factors (the separation
property). We show that there are obstructions to lifting symmetries existing
at a certain number of particles to higher numbers. Such obstructions vanish
for particles without internal degrees of freedom and the usual space-time
symmetries. For particles with internal degrees of freedom, such as spin, these
obstructions are present and their circumvention requires a choice of a new
term in the equation for each particle number. A Lie-algebra approach for
non-linear theories is developed.
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 17:28:25 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Svetlichny",
"George",
""
]
] |
quant-ph/9906118 | Paolo Facchi | P. Facchi, A. Mariano and S. Pascazio | Decoherence vs entropy in neutron interferometry | 13 pages, 5 figures | Phys. Rev. A 63, 052108 (2001) | 10.1103/PhysRevA.63.052108 | null | quant-ph | null | We analyze the coherence properties of polarized neutrons, after they have
interacted with a magnetic field or a phase shifter undergoing different kinds
of statistical fluctuations. We endeavor to probe the degree of disorder of the
distribution of the phase shifts by means of the loss of quantum mechanical
coherence of the neutron. We find that the notion of entropy of the shifts and
that of decoherence of the neutron do not necessarily agree. In some cases the
neutron wave function is more coherent, even though it has interacted with a
more disordered medium.
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 09:59:26 GMT"
},
{
"version": "v2",
"created": "Fri, 21 Jul 2000 09:32:48 GMT"
},
{
"version": "v3",
"created": "Thu, 11 Jan 2001 15:55:01 GMT"
}
] | 2010-01-31T00:00:00 | [
[
"Facchi",
"P.",
""
],
[
"Mariano",
"A.",
""
],
[
"Pascazio",
"S.",
""
]
] |
quant-ph/9906119 | Daniel Faller | H. P. Breuer, D. Faller, B. Kappler, F. Petruccione | Non-Markovian dynamics in pulsed and continuous wave atom lasers | RevTex, 10 pages, 6 Postscript figures, uses multicol. Accepted for
publication in Phys. Rev. A | null | 10.1103/PhysRevA.60.3188 | null | quant-ph | null | The dynamics of atom lasers with a continuous output coupler based on
two-photon Raman transitions is investigated. With the help of the
time-convolutionless projection operator technique the quantum master equations
for pulsed and continuous wave (cw) atom lasers are derived. In the case of the
pulsed atom laser the power of the time-convolutionless projection operator
technique is demonstrated through comparison with the exact solution. It is
shown that in an intermediate coupling regime where the Born-Markov
approximation fails the results of this algorithm agree with the exact
solution. To study the dynamics of a continuous wave atom laser a pump
mechanism is included in the model. Whereas the pump mechanism is treated
within the Born-Markov approximation, the output coupling leads to
non-Markovian effects. The solution of the master equation resulting from the
time-convolutionless projection operator technique exhibits strong oscillations
in the occupation number of the Bose-Einstein condensate. These oscillations
are traced back to a quantum interference which is due to the non-Markovian
dynamics and which decays slowly in time as a result of the dispersion relation
for massive particles.
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 10:05:21 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Breuer",
"H. P.",
""
],
[
"Faller",
"D.",
""
],
[
"Kappler",
"B.",
""
],
[
"Petruccione",
"F.",
""
]
] |
quant-ph/9906120 | Juhi-Lian Julian Ting | Julian Juhi-Lian Ting | Noise effects on One-Pauli Channels | null | Phys.Lett. A259 (1999) 349-354 | 10.1016/S0375-9601(99)00460-0 | null | quant-ph | null | The possibility of stochastic resonance of a quantum channel and hence the
noise enhanced quantum channel capacity is explored by considering one-Pauli
channels which are more classical like. The fidelity of the channel is also
considered.
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 10:10:19 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Ting",
"Julian Juhi-Lian",
""
]
] |
quant-ph/9906121 | Dr. G. Plunien | L. N. Labzowsky, A. V. Nefiodov, G. Plunien, G. Soff, D. Liesen | The hyperfine structure of highly charged $^{238}_{92}$U ions with
rotationally excited nuclei | 10 LaTex pages | Phys.Rev.Lett. 84 (2000) 851-854 | 10.1103/PhysRevLett.84.851 | null | quant-ph | null | The hyperfine structure (hfs) of electron levels of $^{238}_{92}$U ions with
the nucleus excited in the low-lying rotational $2^+$ state with an energy
$E_{2^+} = 44.91$ keV is investigated. In hydrogenlike uranium, the hfs
splitting for the $1s_{1/2}$-ground state of the electron constitutes 1.8 eV.
The hyperfine-quenched (hfq) lifetime of the $1s2p ^3P_0$ state has been
calculated for heliumlike $^{238}_{92}$U and was found to be two orders of
magnitude smaller than for the ion with the nucleus in the ground state. The
possibility of a precise determination of the nuclear $g_r$ factor for the
rotational $2^+$ state by measurements of the hfq lifetime is discussed.
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 10:21:12 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Labzowsky",
"L. N.",
""
],
[
"Nefiodov",
"A. V.",
""
],
[
"Plunien",
"G.",
""
],
[
"Soff",
"G.",
""
],
[
"Liesen",
"D.",
""
]
] |
quant-ph/9906122 | Dr. G. Plunien | G. Plunien, R. Sch\"utzhold, G. Soff | Dynamical Casimir effect at finite temperature | 9 LaTex pages | Phys.Rev.Lett. 84 (2000) 1882-1885 | 10.1103/PhysRevLett.84.1882 | null | quant-ph | null | Thermal effects on the creation of particles under the influence of
time-dependent boundary conditions are investigated. The dominant temperature
correction to the energy radiated by a moving mirror is derived by means of
response theory. For a resonantly vibrating cavity the thermal effect on the
number of created photons is obtained non-perturbatively. Finite temperatures
can enhance the pure vacuum effect by several orders of magnitude. The
relevance of finite temperature effects for the experimental verification of
the dynamical Casimir effect is addressed.
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 12:06:12 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Plunien",
"G.",
""
],
[
"Schützhold",
"R.",
""
],
[
"Soff",
"G.",
""
]
] |
quant-ph/9906123 | Lucien Hardy | Lucien Hardy | Disentangling Nonlocality and Teleportation | 7 pages | null | null | null | quant-ph | null | Quantum entanglement can be used to demonstrate nonlocality and to teleport a
quantum state from one place to another. The fact that entanglement can be used
to do both these things has led people to believe that teleportation is a
nonlocal effect. In this paper it is shown that teleportation is conceptually
independent of nonlocality. This is done by constructing a toy local theory in
which cloning is not possible (without a no-cloning theory teleportation makes
limited sense) but teleportation is. Teleportation in this local theory is
achieved in an analogous way to the way it is done with quantum theory. This
work provides some insight into what type of process teleportation is.
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 14:01:11 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Hardy",
"Lucien",
""
]
] |
quant-ph/9906124 | Lutz Polley | L. Polley | Quantum-mechanical probability from the symmetries of two-state systems | LaTeX, 7 pages, 1 LaTeX figure; major changes in presentation;
argument simplified and generalized; essential reference added | null | null | null | quant-ph | null | In 1989, Deutsch gave a basic physical explanation of why quantum-mechanical
probabilities are squares of amplitudes. Essentially, a general state vector is
transformed into a highly symmetric equal-amplitude superposition. The argument
was recently elaborated and publicised by DeWitt. It has remained incomplete,
however, inasmuch as both authors anticipate the usual normalization (sum of
amplitudes squared) of state vectors. In the present paper, a thought
experiment is devised in which Deutsch's idea is demonstrated independently of
the normalization, exploiting further symmetries instead.
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 14:37:10 GMT"
},
{
"version": "v2",
"created": "Tue, 20 Jul 1999 15:32:57 GMT"
},
{
"version": "v3",
"created": "Wed, 1 Mar 2000 16:49:07 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Polley",
"L.",
""
]
] |
quant-ph/9906125 | John A. Vaccaro | H.M. Wiseman and John A. Vaccaro | Atom lasers, coherent states, and coherence: I. physically realizable
ensembles of pure states | 20 pages, 7 figures. To be published in Phys. Rev. A, as part I of a
two-part paper. This paper is considerably changed from the original version,
and an error has been corrected. Some material from the original version is
in quant-ph/0112145, which is part II of the two-part paper | null | null | null | quant-ph | null | A laser, be it an optical laser or an atom laser, is an open quantum system
that produces a coherent beam of bosons. Far above threshold, the stationary
state $\rho_{ss}$ of the laser mode is a mixture of coherent field states with
random phase, or, equivalently, a Poissonian mixture of number states. This
paper answers the question: can descriptions such as these, of $\rho_{ss}$ as a
stationary ensemble of pure states, be physically realized? An ensemble of pure
states for a particular system can be physically realized if, without changing
the dynamics of the system, an experimenter can (in principle) know at any time
that the system is in one of the pure-state members of the ensemble. Such
knowledge can be obtained by monitoring the baths to which the system is
coupled, provided that coupling is describable by a Markovian master equation.
Using a family of master equations for the (atom) laser, we solve for the
physically realizable (PR) ensembles. We find that for any finite self-energy
$\chi$ of the bosons in the laser mode, the coherent state ensemble is not PR;
the closest one can come to it is an ensemble of squeezed states. This is
particularly relevant for atom lasers, where the self-energy arising from
elastic collisions is expected to be large. By contrast, the number state
ensemble is always PR. As $\chi$ increases, the states in the PR ensemble
closest to the coherent state ensemble become increasingly squeezed.
Nevertheless, there are values of $\chi$ for which states with well-defined
coherent amplitudes are PR, even though the atom laser is not coherent (in the
sense of having a Bose-degenerate output). We discuss the physical significance
of this anomaly in terms of conditional coherence (conditional Bose
degeneracy).
| [
{
"version": "v1",
"created": "Tue, 29 Jun 1999 16:58:19 GMT"
},
{
"version": "v2",
"created": "Sun, 23 Dec 2001 11:47:58 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Wiseman",
"H. M.",
""
],
[
"Vaccaro",
"John A.",
""
]
] |
quant-ph/9906126 | Alexei Ashikhmin | Alexei Ashikhmin, Alexander Barg, Emanuel Knill, and Simon Litsyn | Quantum Error Detection I: Statement of the Problem | null | null | null | null | quant-ph | null | I. This paper is devoted to the problem of error detection with quantum
codes. In the first part we examine possible problem settings for quantum error
detection. Our goal is to derive a functional that describes the probability of
undetected error under natural physical assumptions concerning transmission
with error detection over the depolarizing channel. We discuss possible
transmission protocols with stabilizer and unrestricted quantum codes. The set
of results proved in Part I shows that in all the cases considered the average
probability of undetected error for a given code is essentially given by one
and the same function of its weight enumerators. This enables us to give a
consistent definition of the undetected error event.
| [
{
"version": "v1",
"created": "Wed, 30 Jun 1999 03:08:19 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ashikhmin",
"Alexei",
""
],
[
"Barg",
"Alexander",
""
],
[
"Knill",
"Emanuel",
""
],
[
"Litsyn",
"Simon",
""
]
] |
quant-ph/9906127 | Michael Weissman | M. B. Weissman (U. of Illinois, Urbana-Champaign) | Emergent measure-dependent probabilities from modified quantum dynamics
without state-vector reduction | Latex; to appear in Foundations of Physics Letters | Found.Phys.Lett. 12 (1999) 407-426 | null | UIUC P-99-06-05 | quant-ph | null | Counting outcomes is the obvious algorithm for generating probabilities in
quantum mechanics without state-vector reduction (i.e. many-worlds). This
procedure has usually been rejected because for purely linear dynamics it gives
results in disagreement with experiment. Here it is shown that if non-linear
decoherence effects (previously proposed by other authors) are combined with an
exponential time dependence of the scale for the non-linear effects, the
correct measure-dependent probabilities can emerge via outcome counting,
without the addition of any stochastic fields or metaphysical hypotheses.
| [
{
"version": "v1",
"created": "Wed, 30 Jun 1999 05:56:09 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Weissman",
"M. B.",
"",
"U. of Illinois, Urbana-Champaign"
]
] |
quant-ph/9906128 | Carsten Henkel | Carsten Henkel, Sierk Poetting, and Martin Wilkens | Loss and heating of particles in small and noisy traps | Slightly modified manuscript, as accepted for publication in Appl.
Phys. B (04 oct 1999). 10 pages, 5 .eps figures, LaTeX uses Springer style
file svjour | Appl. Phys. B 69 (1999) 379-387 | 10.1007/s003400050823 | null | quant-ph | null | We derive the life time and loss rate for a trapped particle that is coupled
to fluctuating fields in the vicinity of a room-temperature metallic and/or
dielectric surface. Our results indicate a clear predominance of near field
effects over ordinary blackbody radiation. We develop a theoretical framework
for both charged and neutral particles with and without spin. Loss processes
that are due to a transition to an untrapped internal state are included.
| [
{
"version": "v1",
"created": "Wed, 30 Jun 1999 10:13:56 GMT"
},
{
"version": "v2",
"created": "Mon, 11 Oct 1999 07:31:34 GMT"
}
] | 2021-08-06T00:00:00 | [
[
"Henkel",
"Carsten",
""
],
[
"Poetting",
"Sierk",
""
],
[
"Wilkens",
"Martin",
""
]
] |
quant-ph/9906129 | Dorit Aharonov | Dorit Aharonov and Michael Ben-Or | Fault-Tolerant Quantum Computation With Constant Error Rate | 63 pages. Submitted to SIAM journal of computation. Considerably
extended version of our STOC paper containing the threshold result
(quant-ph/9611025) | null | null | null | quant-ph | null | This paper proves the threshold result, which asserts that quantum
computation can be made robust against errors and inaccuracies, when the error
rate, $\eta$, is smaller than a constant threshold, $\eta_c$. The result holds
for a very general, not necessarily probabilistic noise model, for quantum
particles with any number of states, and is also generalized to one dimensional
quantum computers with only nearest neighbor interactions. No measurements, or
classical operations, are required during the quantum computation. The
proceeding version was very succinct, and here we fill all the missing details,
and elaborate on many parts of the proof. In particular, we devote a section
for a discussion of universality issues and proofs that the sets of gates that
we use are universal. Another section is devoted to a rigorous proof that fault
tolerance can be achieved in the presence of general non probabilistic noise.
The systematic structure of the fault tolerant procedures for polynomial codes
is explained in length. The proof that the concatenation scheme works is
written in a clearer way. The paper also contains new and significantly simpler
proofs for most of the known results which we use. For example, we give a
simple proof that it suffices to correct bit and phase flips, we significantly
simplify Calderbank and Shor's original proof of the correctness of CSS codes.
We also give a simple proof of the fact that two-qubit gates are universal. The
paper thus provides a self contained and complete proof for universal fault
tolerant quantum computation.
| [
{
"version": "v1",
"created": "Wed, 30 Jun 1999 15:06:18 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Aharonov",
"Dorit",
""
],
[
"Ben-Or",
"Michael",
""
]
] |
quant-ph/9906130 | Toshihiko Ono | Toshihiko Ono | Structure behind Mechanics | 55 pages | null | null | null | quant-ph hep-th physics.class-ph | null | This paper proposes a basic theory on physical reality, and a new foundation
for quantum mechanics and classical mechanics. It does not only solve the
problem of the arbitrariness on the operator ordering for the quantization
procedure, but also clarifies how the classical-limit occurs. It further
compares the new theory with the known quantization methods, and proposes a
self-consistent interpretation for quantum mechanics. It also provides the
internal structure inducing half-integer spin of a particle, the sense of the
regularization in the quantum field theory, the quantization of a
phenomenological system, the causality in quantum mechanics and the origin of
the thermodynamic irreversibility under the new insight.
| [
{
"version": "v1",
"created": "Wed, 30 Jun 1999 21:36:18 GMT"
},
{
"version": "v10",
"created": "Wed, 8 Sep 1999 18:08:22 GMT"
},
{
"version": "v2",
"created": "Mon, 5 Jul 1999 20:04:51 GMT"
},
{
"version": "v3",
"created": "Wed, 7 Jul 1999 15:43:43 GMT"
},
{
"version": "v4",
"created": "Mon, 12 Jul 1999 17:41:36 GMT"
},
{
"version": "v5",
"created": "Thu, 29 Jul 1999 20:03:54 GMT"
},
{
"version": "v6",
"created": "Fri, 30 Jul 1999 01:52:03 GMT"
},
{
"version": "v7",
"created": "Sun, 1 Aug 1999 20:01:57 GMT"
},
{
"version": "v8",
"created": "Sun, 8 Aug 1999 21:46:55 GMT"
},
{
"version": "v9",
"created": "Tue, 10 Aug 1999 22:14:24 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ono",
"Toshihiko",
""
]
] |
quant-ph/9906131 | Alexei Ashikhmin | A. Ashikhmin, A. Barg, E. Knill, and S. Litsyn | Quantum Error Detection II: Bounds | null | null | null | null | quant-ph | null | In Part II we show that there exist quantum codes whose probability of
undetected error falls exponentially with the length of the code and derive
bounds on this exponent.The lower (existence) bound for stabilizer codes is
proved by a counting argument for classical self-orthogonal quaternary codes.
Upper bounds for any quantum codes are proved by linear programming. We present
two general solutions of the LP problem. Together they give an upper bound on
the exponent of undetected error. The upper and lower asymptotic bounds
coincide for a certain interval of code rates close to 1.
| [
{
"version": "v1",
"created": "Wed, 30 Jun 1999 21:06:13 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ashikhmin",
"A.",
""
],
[
"Barg",
"A.",
""
],
[
"Knill",
"E.",
""
],
[
"Litsyn",
"S.",
""
]
] |
quant-ph/9907001 | Sibasish Ghosh | Sibasish Ghosh, Guruprasad Kar, Anirban Roy | Optimal Cloning and No Signaling | 6 pages, latex | Phys.Lett. A261 (1999) 17-19 | 10.1016/S0375-9601(99)00562-9 | null | quant-ph | null | It is shown that no signaling constraint generates the whole class of 1
$\rightarrow$ 2 optimal quantum cloning machines of single qubits.
| [
{
"version": "v1",
"created": "Thu, 1 Jul 1999 12:15:42 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Ghosh",
"Sibasish",
""
],
[
"Kar",
"Guruprasad",
""
],
[
"Roy",
"Anirban",
""
]
] |
quant-ph/9907002 | Arturo Lezama | A. Lezama S. Barreiro A. Lipsich A.M. Akulshin | Coherent two-field spectroscopy of degenerate two-level systems | 13 pages, 12 figures | null | null | null | quant-ph | null | Spectroscopic features revealing the coherent interaction of a degenerate
two-level atomic system with two optical fields are examined. A model for the
numerical calculation of the response of a degenerate two-level system to the
action of an arbitrarily intense resonant pump field and a weak probe in the
presence of a magnetic field is presented. The model is valid for arbitrary
values of the total angular momentum of the lower and upper levels and for any
choice of the polarizations of the optical waves. Closed and open degenerate
two-level systems are considered. Predictions for probe absorption and
dispersion, field generation by four-wave-mixing, population modulation and
Zeeman optical pumping are derived. On all these observables, sub-natural-width
coherence resonances are predicted and their spectroscopic features are
discussed. Experimental spectra for probe absorption and excited state
population modulation in the D2 line of Rb vapor are presented in good
agreement with the calculations
| [
{
"version": "v1",
"created": "Thu, 1 Jul 1999 12:19:01 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Akulshin",
"A. Lezama S. Barreiro A. Lipsich A. M.",
""
]
] |
quant-ph/9907003 | Noah Linden | Noah Linden, Eriks Kupce, Ray Freeman | NMR Quantum Logic Gates for Homonuclear Spin Systems | 11 pages LaTeX plus 6 figs | null | 10.1016/S0009-2614(99)00829-5 | null | quant-ph | null | If NMR systems are to be used as practical quantum computers, the number of
coupled spins will need to be so large that it is not feasible to rely on
purely heteronuclear spin systems. The implementation of a quantum logic gate
imposes certain constraints on the motion of those spins not directly involved
in that gate, the so-called "spectator" spins; they must be returned to their
initial states at the end of the sequence. As a result, a homonuclear spin
system where there is appreciable coupling between every pair of spins would
seem to require a refocusing scheme that doubles in complexity and duration for
every additional spectator spin. Fortunately, for the more realistic practical
case where long-range spin-spin couplings can be neglected, simpler refocusing
schemes can be devised where the overall duration of the sequence remains
constant and the number of soft pulses increases only linearly with the number
of spectator spins. These ideas are tested experimentally on a six qubit
system: the six coupled protons of inosine.
| [
{
"version": "v1",
"created": "Thu, 1 Jul 1999 15:23:24 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Linden",
"Noah",
""
],
[
"Kupce",
"Eriks",
""
],
[
"Freeman",
"Ray",
""
]
] |
quant-ph/9907004 | Jerry Finkelstein | J. Finkelstein (LBNL and SJSU) | Quantum Probability from Decision Theory? | LaTeX, 5 pages, no figures | null | null | SJSU/TP-99-20 | quant-ph | null | Deutsch has recently (in quant-ph/9906015) offered a justification, based
only on the non-probabilistic axioms of quantum theory and of classical
decision theory, for the use of the standard quantum probability rules. In this
note, this justification is examined.
| [
{
"version": "v1",
"created": "Thu, 1 Jul 1999 18:37:06 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Finkelstein",
"J.",
"",
"LBNL and SJSU"
]
] |
quant-ph/9907005 | Armen G. Grigoryan | A.S.Gevorkyan, A.A.Udalov | Randomly Walking 1D Quantum Harmonic Oscillator. Averaged Transition
Probabilities | LaTeX, SPROCL.STY required, presented on 3rd Int. Workshop "Quantum
Systems: New Trends & Methods" (Minsk, Belarus) | null | null | null | quant-ph | null | One-dimensional problem for quantum harmonic oscillator with "regular+random"
frequency subjected to the external "regular+random" force is considered.
Averaged transition probabilities are found.
| [
{
"version": "v1",
"created": "Thu, 1 Jul 1999 19:40:39 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gevorkyan",
"A. S.",
""
],
[
"Udalov",
"A. A.",
""
]
] |
quant-ph/9907006 | Nicolas Gisin | Andr\'e Stefanov, Nicolas Gisin, Olivier Guinnard, Laurent Guinnard,
Hugo Zbinden | Optical Quantum Random Number Generator | 3 pages + 1 figure | J. Modern Optics, 47, 595-598, 2000 | 10.1080/09500340008233380 | null | quant-ph | null | A physical random number generator based on the intrinsic randomness of
quantum mechanics is described. The random events are realized by the choice of
single photons between the two outputs of a beamsplitter. We present a simple
device, which minimizes the impact of the photon counters' noise, dead-time and
after pulses.
| [
{
"version": "v1",
"created": "Fri, 2 Jul 1999 08:21:02 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Stefanov",
"André",
""
],
[
"Gisin",
"Nicolas",
""
],
[
"Guinnard",
"Olivier",
""
],
[
"Guinnard",
"Laurent",
""
],
[
"Zbinden",
"Hugo",
""
]
] |
quant-ph/9907007 | Richard Jozsa | Graeme Mitchison and Richard Jozsa | Counterfactual Computation | 19 pages. LaTex, 2 figures. Revised version has some new sections and
expanded explanations | Proc.Roy.Soc.Lond. A457 (2001) 1175-1194 | 10.1098/rspa.2000.0714 | null | quant-ph | null | Suppose that we are given a quantum computer programmed ready to perform a
computation if it is switched on. Counterfactual computation is a process by
which the result of the computation may be learnt without actually running the
computer. Such processes are possible within quantum physics and to achieve
this effect, a computer embodying the possibility of running the computation
must be available, even though the computation is, in fact, not run. We study
the possibilities and limitations of general protocols for the counterfactual
computation of decision problems (where the result r is either 0 or 1). If p(r)
denotes the probability of learning the result r ``for free'' in a protocol
then one might hope to design a protocol which simultaneously has large p(0)
and p(1). However we prove that p(0)+p(1) never exceeds 1 in any protocol and
we derive further constraints on p(0) and p(1) in terms of N, the number of
times that the computer is not run. In particular we show that any protocol
with p(0)+p(1)=1-epsilon must have N tending to infinity as epsilon tends to 0.
These general results are illustrated with some explicit protocols for
counterfactual computation. We show that "interaction-free" measurements can be
regarded as counterfactual computations, and our results then imply that N must
be large if the probability of interaction is to be close to zero. Finally, we
consider some ways in which our formulation of counterfactual computation can
be generalised.
| [
{
"version": "v1",
"created": "Fri, 2 Jul 1999 14:52:18 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Oct 2000 15:41:51 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Mitchison",
"Graeme",
""
],
[
"Jozsa",
"Richard",
""
]
] |
quant-ph/9907008 | Fred Cooper | Carl Bender, Fred Cooper, Peter Meisinger and Van M. Savage | Variational Ansatz for PT-Symmetric Quantum Mechanics | 9 pages -- one postscript figure | Phys.Lett. A259 (1999) 224-231 | 10.1016/S0375-9601(99)00468-5 | LA-UR-99-3026 | quant-ph | null | A variational calculation of the energy levels of a class of PT-invariant
quantum mechanical models described by the non-Hermitian Hamiltonian H= p^2 -
(ix)^N with N positive and x complex is presented. Excellent agreement is
obtained for the ground state and low lying excited state energy levels and
wave functions. We use an energy functional with a three parameter class of
PT-symmetric trial wave functions in obtaining our results.
| [
{
"version": "v1",
"created": "Fri, 2 Jul 1999 20:20:04 GMT"
}
] | 2009-10-31T00:00:00 | [
[
"Bender",
"Carl",
""
],
[
"Cooper",
"Fred",
""
],
[
"Meisinger",
"Peter",
""
],
[
"Savage",
"Van M.",
""
]
] |
quant-ph/9907009 | Max Tegmark | Max Tegmark | The importance of quantum decoherence in brain processes | Minor changes to match accepted PRE version. 15 pages with 5 figs
included. Color figures and links at
http://www.physics.upenn.edu/~max/brain.html or from [email protected].
Physical Review E, in press | Phys.Rev.E61:4194-4206,2000 | 10.1103/PhysRevE.61.4194 | null | quant-ph cond-mat.dis-nn cs.NE physics.bio-ph q-bio | null | Based on a calculation of neural decoherence rates, we argue that that the
degrees of freedom of the human brain that relate to cognitive processes should
be thought of as a classical rather than quantum system, i.e., that there is
nothing fundamentally wrong with the current classical approach to neural
network simulations. We find that the decoherence timescales ~10^{-13}-10^{-20}
seconds are typically much shorter than the relevant dynamical timescales
(~0.001-0.1 seconds), both for regular neuron firing and for kink-like
polarization excitations in microtubules. This conclusion disagrees with
suggestions by Penrose and others that the brain acts as a quantum computer,
and that quantum coherence is related to consciousness in a fundamental way.
| [
{
"version": "v1",
"created": "Mon, 5 Jul 1999 10:33:19 GMT"
},
{
"version": "v2",
"created": "Wed, 10 Nov 1999 01:45:08 GMT"
}
] | 2009-10-07T00:00:00 | [
[
"Tegmark",
"Max",
""
]
] |
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