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quant-ph/9908025
Emmanuel Paspalakis
Emmanuel Paspalakis
Physical Interpretation of Laser-Induced Suppression of Quantum Tunneling
4 pages text, 1 figure. Submitted for publication
null
10.1016/S0375-9601(99)00630-1
null
quant-ph
null
We revisit the problem of laser-induced suppression of quantum dynamical tunneling in a model system studied by Kilin et al. [Phys. Rev. Lett. 76 (1996) 3297]. This quantum system consists of a ground state symmetric double-well potential which is coupled by a strong laser field to an excited state asymmetric double-well potential. By analyzing the assumptions used in their analysis we show that the suppression of quantum dynamical tunneling can be explained with the use of dark and bright states of the system. We also generalize the system and the conditions for suppression of quantum tunneling and show that, in certain cases, suppression can occur regardless the characteristics of the excited potential surface.
[ { "version": "v1", "created": "Fri, 6 Aug 1999 11:55:29 GMT" } ]
2016-09-08T00:00:00
[ [ "Paspalakis", "Emmanuel", "" ] ]
quant-ph/9908026
Emmanuel Paspalakis
E. Paspalakis, N. J. Kylstra and P. L. Knight
Transparency Near a Photonic Band Edge
3 pages text, 2 figures
Physical Review A, Vol. 60, R33-R36 (1999)
10.1103/PhysRevA.60.R33
null
quant-ph
null
We study the absorption and dispersion properties of a ${\bf \Lambda}$-type atom which decays spontaneously near the edge of a photonic band gap (PBG). Using an isotropic PBG model, we show that the atom can become transparent to a probe laser field, even when other dissipative channels are present. This transparency originates from the square root singularity of the density of modes of the PBG material at threshold.
[ { "version": "v1", "created": "Fri, 6 Aug 1999 13:47:15 GMT" } ]
2009-10-31T00:00:00
[ [ "Paspalakis", "E.", "" ], [ "Kylstra", "N. J.", "" ], [ "Knight", "P. L.", "" ] ]
quant-ph/9908027
null
C.R. Hagen
Galilean Lee Model of the Delta Function Potential
7 pages, latex, no figures
null
10.1103/PhysRevA.61.032715
null
quant-ph hep-th math-ph math.MP
null
The scattering cross section associated with a two dimensional delta function has recently been the object of considerable study. It is shown here that this problem can be put into a field theoretical framework by the construction of an appropriate Galilean covariant theory. The Lee model with a standard Yukawa interaction is shown to provide such a realization. The usual results for delta function scattering are then obtained in the case that a stable particle exists in the scattering channel provided that a certain limit is taken in the relevant parameter space. In the more general case in which no such limit is taken finite corrections to the cross section are obtained which (unlike the pure delta function case) depend on the coupling constant of the model.
[ { "version": "v1", "created": "Fri, 6 Aug 1999 16:37:27 GMT" } ]
2009-10-31T00:00:00
[ [ "Hagen", "C. R.", "" ] ]
quant-ph/9908028
Hans Halvorson
Rob Clifton (Depts. of Philosophy and History & Philosophy of Science, University of Pittsburgh) and Hans Halvorson (Depts. of Mathematics and Philosophy, University of Pittsburgh)
Bipartite Mixed States of Infinite-Dimensional Systems are Generically Nonseparable
5 pages, RevTeX
Phys. Rev. A 61, 012108 (2000)
10.1103/PhysRevA.61.012108
null
quant-ph
null
Given a bipartite quantum system represented by a tensor product of two Hilbert spaces, we give an elementary argument showing that if either component space is infinite-dimensional, then the set of nonseparable density operators is trace-norm dense in the set of all density operators (and the separable density operators nowhere dense). This result complements recent detailed investigations of separability, which show that when both component Hilbert spaces are finite-dimensional, there is a separable neighborhood (perhaps very small for large dimensions) of the maximally mixed state.
[ { "version": "v1", "created": "Sun, 8 Aug 1999 17:22:47 GMT" } ]
2009-10-31T00:00:00
[ [ "Clifton", "Rob", "", "Depts. of Philosophy and History & Philosophy of Science,\n University of Pittsburgh" ], [ "Halvorson", "Hans", "", "Depts. of Mathematics and\n Philosophy, University of Pittsburgh" ] ]
quant-ph/9908029
David Marcus Appleby
D. M. Appleby
Bohmian Trajectories Post-Decoherence
21 pages, AMS Latex
Found.Phys. 29 (1999) 1885-1916
null
QMW-PH-99-11
quant-ph
null
The proposal that the interaction between a macroscopic body and its environment plays a crucial role in producing the correct classical limit in the Bohm interpretation of quantum mechanics is investigated, in the context of a model of quantum Brownian motion. It is well known that one of the effects of the interaction is to produce an extremely rapid approximate diagonalisation of the reduced density matrix in the position representation. This effect is, by itself, insufficient to produce generically quasi-classical behaviour of the Bohmian trajectory. However, it is shown that, if the system particle is initially in an approximate energy eigenstate, then there is a tendency for the Bohmian trajectory to become approximately classical on a rather longer time-scale. The relationship between this phenomenon and the behaviour of the Wigner function post-decoherence (as analysed by Halliwell and Zoupas) is discussed. It is also suggested that the phenomenon may be related to the storage of information about the trajectory in the environment, and that it may therefore be a general feature of every situation in which such environmental monitoring occurs.
[ { "version": "v1", "created": "Sun, 8 Aug 1999 22:26:34 GMT" } ]
2007-05-23T00:00:00
[ [ "Appleby", "D. M.", "" ] ]
quant-ph/9908030
Tommaso Calarco
Tommaso Calarco (1), Marcello Cini (2), and Roberto Onofrio (3) ((1)Institut fuer Theoretische Physik - Universitaet Innsbruck and ECT* (Trento); (2) Dipartimento di Fisica - Universita' di Roma "La Sapienza" and INFN, Sezione di Roma; (3) Dipartimento di Fisica "G. Galilei" -Universita' di Padova and INFM, Sezione di Roma 1)
Are violations to temporal Bell inequalities there when somebody looks?
7 pages, 1 eps figure, needs europhys.sty and euromacr.tex, enclosed in the .tar.gz file; accepted for publication in Europhysics Letters
null
10.1209/epl/i1999-00403-3
ECT*-99-006
quant-ph
null
The possibility of observing violations of temporal Bell inequalities, originally proposed by Leggett as a mean of testing the quantum mechanical delocalization of suitably chosen macroscopic bodies, is discussed by taking into account the effect of the measurement process. A general criterion quantifying this possibility is defined and shown not to be fulfilled by the various experimental configurations proposed so far to test inequalities of different forms.
[ { "version": "v1", "created": "Mon, 9 Aug 1999 09:09:18 GMT" } ]
2009-10-31T00:00:00
[ [ "Calarco", "Tommaso", "" ], [ "Cini", "Marcello", "" ], [ "Onofrio", "Roberto", "" ] ]
quant-ph/9908031
Adrian Kent
Rob Clifton (Depts of Philosophy and History and Philosophy of Science, University of Pittsburgh) and Adrian Kent (Centre for Quantum Computation, University of Oxford and DAMTP, University of Cambridge)
Simulating Quantum Mechanics by Non-Contextual Hidden Variables
15 pages. Journal version. Only minor typo corrections from last version
Proc. Roy. Soc. Lond. A (2000) 456, 2101-2114.
10.1098/rspa.2000.0604
DAMTP-1999-95
quant-ph
null
No physical measurement can be performed with infinite precision. This leaves a loophole in the standard no-go arguments against non-contextual hidden variables. All such arguments rely on choosing special sets of quantum-mechanical observables with measurement outcomes that cannot be simulated non-contextually. As a consequence, these arguments do not exclude the hypothesis that the class of physical measurements in fact corresponds to a dense subset of all theoretically possible measurements with outcomes and quantum probabilities that \emph{can} be recovered from a non-contextual hidden variable model. We show here by explicit construction that there are indeed such non-contextual hidden variable models, both for projection valued and positive operator valued measurements.
[ { "version": "v1", "created": "Mon, 9 Aug 1999 12:24:26 GMT" }, { "version": "v2", "created": "Tue, 24 Aug 1999 09:15:45 GMT" }, { "version": "v3", "created": "Fri, 18 Feb 2000 15:19:29 GMT" }, { "version": "v4", "created": "Mon, 29 May 2000 22:03:14 GMT" } ]
2009-10-31T00:00:00
[ [ "Clifton", "Rob", "", "Depts of Philosophy and History and Philosophy of\n Science, University of Pittsburgh" ], [ "Kent", "Adrian", "", "Centre for Quantum\n Computation, University of Oxford and DAMTP, University of Cambridge" ] ]
quant-ph/9908032
Micho Durdevich
Micho Durdevich
Physics Beyond the Limits of Uncertainty Relations
AMSLaTeX, 8 pages. An online version of the paper is available at the Author's website. Visit http://www.matem.unam.mx/~micho for more details
null
null
null
quant-ph math.QA
null
The paper is a brief informal introduction to C*-algebraic foundations of causal contextual subquantum theories. In particular, it is explained how the contextuality property (which is a necessary consistency condition of all causal subquantum theories) naturally appears within the framework of certain C*-algebraic extensions of the quantum observables algebras. Furthermore, a question of locality is discussed. It is explained that the appropriate non-Kolmogorovian probability theory allows us to unify both locality and causality with the principles of quantum mechanics, overcoming the obstacles given by Bell's inequalities.
[ { "version": "v1", "created": "Tue, 10 Aug 1999 01:55:31 GMT" } ]
2007-05-23T00:00:00
[ [ "Durdevich", "Micho", "" ] ]
quant-ph/9908033
Eric A. Galapon
Eric A. Galapon (Theoretical Physics Group, National Institute of Physics, University of the Philippines at Diliman)
Pauli's Theorem and Quantum Canonical Pairs: The Consistency Of a Bounded, Self-Adjoint Time Operator Canonically Conjugate to a Hamiltonian with Non-empty Point Spectrum
contains corrections to minor typographical errors of the published version
Proc. R. Soc. Lond. A, 458 (2002) 451-472
10.1098/rspa.2001.0874
null
quant-ph math-ph math.MP
null
In single Hilbert space, Pauli's well-known theorem implies that the existence of a self-adjoint time operator canonically conjugate to a given Hamiltonian signifies that the time operator and the Hamiltonian possess completely continuous spectra spanning the entire real line. Thus the conclusion that there exists no self-adjoint time operator conjugate to a semibounded or discrete Hamiltonian despite some well-known illustrative counterexamples. In this paper we evaluate Pauli's theorem against the single Hilbert space formulation of quantum mechanics, and consequently show the consistency of assuming a bounded, self-adjoint time operator canonically conjugate to a Hamiltonian with an unbounded, or semibounded, or finite point spectrum. We point out Pauli's implicit assumptions and show that they are not consistent in a single Hilbert space. We demonstrate our analysis by giving two explicit examples. Moreover, we clarify issues sorrounding the different solutions to the canonical commutation relations, and, consequently, expand the class of acceptable canonical pairs beyond the solutions required by Pauli's theorem.
[ { "version": "v1", "created": "Wed, 11 Aug 1999 08:24:24 GMT" }, { "version": "v2", "created": "Tue, 28 Sep 1999 17:59:57 GMT" }, { "version": "v3", "created": "Wed, 21 Jun 2000 12:12:03 GMT" }, { "version": "v4", "created": "Fri, 5 Apr 2002 08:21:27 GMT" } ]
2009-10-31T00:00:00
[ [ "Galapon", "Eric A.", "", "Theoretical Physics Group, National Institute of\n Physics, University of the Philippines at Diliman" ] ]
quant-ph/9908034
Antonio Vidiella-Barranco
H. Moya-Cessa, J.A. Roversi, S.M. Dutra, A. Vidiella-Barranco (Universidade Estadual de Campinas)
Recovering coherence from decoherence: a method of quantum state reconstruction
8 pages, in RevTeX, 4 figures, accepted for publication in Phys. Rev. A (november 1999)
Phys. Rev. A 60, 4029 (1999).
10.1103/PhysRevA.60.4029
null
quant-ph
null
We present a feasible scheme for reconstructing the quantum state of a field prepared inside a lossy cavity. Quantum coherences are normally destroyed by dissipation, but we show that at zero temperature we are able to retrieve enough information about the initial state, making possible to recover its Wigner function as well as other quasiprobabilities. We provide a numerical simulation of a Schroedinger cat state reconstruction.
[ { "version": "v1", "created": "Wed, 11 Aug 1999 13:14:27 GMT" } ]
2009-10-31T00:00:00
[ [ "Moya-Cessa", "H.", "", "Universidade Estadual de Campinas" ], [ "Roversi", "J. A.", "", "Universidade Estadual de Campinas" ], [ "Dutra", "S. M.", "", "Universidade Estadual de Campinas" ], [ "Vidiella-Barranco", "A.", "", "Universidade Estadual de Campinas" ] ]
quant-ph/9908035
Morgan W. Mitchell
Ari Mizel, M. W. Mitchell, and Marvin L. Cohen
Ground State Quantum Computation
4 pages, 2 figures
null
10.1103/PhysRevA.63.040302
null
quant-ph
null
We formulate a novel ground state quantum computation approach that requires no unitary evolution of qubits in time: the qubits are fixed in stationary states of the Hamiltonian. This formulation supplies a completely time-independent approach to realizing quantum computers. We give a concrete suggestion for a ground state quantum computer involving linked quantum dots.
[ { "version": "v1", "created": "Wed, 11 Aug 1999 21:15:53 GMT" } ]
2013-05-29T00:00:00
[ [ "Mizel", "Ari", "" ], [ "Mitchell", "M. W.", "" ], [ "Cohen", "Marvin L.", "" ] ]
quant-ph/9908036
Gerard Milburn
Samuel L.Braunstein, Giacomo M.D'Ariano, G.J.Milburn, and Massimiliano F. Sacchi
Universal teleportation with a twist
4 pages, 1 figure
Phys. Rev. Lett. 84, 3486 (2000)
10.1103/PhysRevLett.84.3486
null
quant-ph
null
We give a transfer theorem for teleportation based on twisting the entanglement measurement. This allows one to say what local unitary operation must be performed to complete the teleportation in any situation, generalizing the scheme to include overcomplete measurements, non-abelian groups of local unitary operations (e.g., angular momentum teleportation), and the effect of non-maximally entangled resources.
[ { "version": "v1", "created": "Thu, 12 Aug 1999 05:22:38 GMT" } ]
2009-10-31T00:00:00
[ [ "Braunstein", "Samuel L.", "" ], [ "D'Ariano", "Giacomo M.", "" ], [ "Milburn", "G. J.", "" ], [ "Sacchi", "Massimiliano F.", "" ] ]
quant-ph/9908037
Gerard Milburn
G.J.Milburn
Simulating nonlinear spin models in an ion trap
4 pages
null
null
null
quant-ph
null
We show how a conditional displacement of the vibrational mode of trapped ions can be used to simulate nonlinear collective and interacting spin systems including nonlinear tops and Ising models (a universal two qubit gate), independent of the vibrational state of the ion. Thus cooling to the vibrational ground state is unnecessary provided the heating rate is not too large.
[ { "version": "v1", "created": "Thu, 12 Aug 1999 06:00:16 GMT" } ]
2007-05-23T00:00:00
[ [ "Milburn", "G. J.", "" ] ]
quant-ph/9908038
Victor Dodonov
V.V.Dodonov and M.A.Andreata
Squeezing and photon distribution in a vibrating cavity
20 pages, LaTex2e, iopart document class, 2 ps figures, accepted for publication in J. Phys. A
J. Phys. A, v.32, no.39, p.6711-6726 (1999)
10.1088/0305-4470/32/39/301
null
quant-ph
null
We obtain explicit analytical expressions for the quadrature variances and the photon distribution functions of the electromagnetic field modes excited from vacuum or thermal states due to the non-stationary Casimir effect in an ideal one-dimensional Fabry--Perot cavity with vibrating walls, provided the frequency of vibrations is close to a multiple frequency of the fundamental unperturbed electromagnetic mode.
[ { "version": "v1", "created": "Thu, 12 Aug 1999 13:34:41 GMT" } ]
2009-10-31T00:00:00
[ [ "Dodonov", "V. V.", "" ], [ "Andreata", "M. A.", "" ] ]
quant-ph/9908039
Jose L. Cereceda
Jose L. Cereceda
Quantum perfect correlations and Hardy's nonlocality theorem
LaTeX, 24 pages, 1 figure
Found. Phys. Lett. 12 (1999) 211-231
null
null
quant-ph
null
In this paper the failure of Hardy's nonlocality proof for the class of maximally entangled states is considered. A detailed analysis shows that the incompatibility of the Hardy equations for this class of states physically originates from the fact that the existence of quantum perfect correlations for the three pairs of two-valued observables (D_11,D_21), (D_11,D_22) and (D_12,D_21) [in the sense of having with certainty equal (different) readings for a joint measurement of any one of the pairs (D_11,D_21), (D_11,D_22), and (D_12,D_21)], necessarily entails perfect correlation for the pair of observables (D_12,D_22) [in the sense of having with certainty equal (different) readings for a joint measurement of the pair (D_12,D_22)]. Indeed, the set of these four perfect correlations is found to satisfy the CHSH inequality, and then no violations of local realism will arise for the maximally entangled state as far as the four observables D_ij, i,j = 1,2, are concerned. The connection between this fact and the impossibility for the quantum mechanical predictions to give the maximum possible theoretical violation of the CHSH inequality is pointed out. Moreover, it is generally proved that the fulfillment of all the Hardy nonlocality conditions necessarily entails a violation of the resulting CHSH inequality. The largest violation of this latter inequality is determined.
[ { "version": "v1", "created": "Thu, 12 Aug 1999 18:29:32 GMT" } ]
2007-05-23T00:00:00
[ [ "Cereceda", "Jose L.", "" ] ]
quant-ph/9908040
Andrei N. Soklakov
A. N. Soklakov and R. Schack
Classical limit in terms of symbolic dynamics for the quantum baker's map
12 pages, LaTex, typos corrected
Phys. Rev. E 61, 5108 (2000)
10.1103/PhysRevE.61.5108
null
quant-ph
null
We derive a simple closed form for the matrix elements of the quantum baker's map that shows that the map is an approximate shift in a symbolic representation based on discrete phase space. We use this result to give a formal proof that the quantum baker's map approaches a classical Bernoulli shift in the limit of a small effective Plank's constant.
[ { "version": "v1", "created": "Thu, 12 Aug 1999 21:44:36 GMT" }, { "version": "v2", "created": "Sun, 15 Jul 2001 23:34:48 GMT" } ]
2016-09-08T00:00:00
[ [ "Soklakov", "A. N.", "" ], [ "Schack", "R.", "" ] ]
quant-ph/9908041
Luis Santos
Luis Santos and Dagmar Bruss
Reversible quantum teleportation in an optical lattice
8 pages, 3 figures
J. Phys. A: Math. Gen. 34, 7003 (2001)
10.1088/0305-4470/34/35/326
null
quant-ph
null
We propose a protocol, based on entanglement procedures recently suggested by [D. Jaksch et al., Phys. Rev. Lett. 82, 1975 (1999)], which allows the teleportation of an unknown state of a neutral atom in an optical lattice to another atom in another site of the lattice, without any irreversible detection.
[ { "version": "v1", "created": "Fri, 13 Aug 1999 09:08:59 GMT" } ]
2009-10-31T00:00:00
[ [ "Santos", "Luis", "" ], [ "Bruss", "Dagmar", "" ] ]
quant-ph/9908042
Dr. V. Krasnoholovets
Volodymyr Krasnoholovets
On the Way to Submicroscopic Description of Nature
LaTeX 2e, 13 pages, 1 figure (PostScript file); minor changes have been made
Indian Journal of Theoretical Physics, vol. 49, no. 2, pp. 81-95 (2001)
null
null
quant-ph
null
The outline analyzes the principal difficulties, which emerge at the applying of modern quantum theory based on the Copenhagen School concept to phenomena developed in the range close to 10^{-28} cm (the point of intersection of the three fundamental interactions). It is shown that at this scale, the interaction of a moving particle with space plays an essential role and just space assigns wave and quantum properties to the particle. The main physical aspects of space structure are discussed herein.
[ { "version": "v1", "created": "Fri, 13 Aug 1999 10:10:04 GMT" }, { "version": "v2", "created": "Wed, 3 Nov 1999 08:37:26 GMT" }, { "version": "v3", "created": "Fri, 5 Nov 1999 09:42:45 GMT" }, { "version": "v4", "created": "Tue, 9 Oct 2001 09:34:06 GMT" } ]
2009-09-25T00:00:00
[ [ "Krasnoholovets", "Volodymyr", "" ] ]
quant-ph/9908043
Seth Lloyd
Seth Lloyd (MIT)
Ultimate physical limits to computation
22 pages, plain TeX, submitted to Nature, replaced to incorporate additional content and references
null
10.1038/35023282
null
quant-ph
null
Computers are physical systems: what they can and cannot do is dictated by the laws of physics. In particular, the speed with which a physical device can process information is limited by its energy and the amount of information that it can process is limited by the number of degrees of freedom it possesses. This paper explores the physical limits of computation as determined by the speed of light $c$, the quantum scale $\hbar$ and the gravitational constant $G$. As an example, quantitative bounds are put to the computational power of an `ultimate laptop' with a mass of one kilogram confined to a volume of one liter.
[ { "version": "v1", "created": "Fri, 13 Aug 1999 14:04:55 GMT" }, { "version": "v2", "created": "Mon, 16 Aug 1999 10:53:26 GMT" }, { "version": "v3", "created": "Mon, 14 Feb 2000 22:41:43 GMT" } ]
2015-06-26T00:00:00
[ [ "Lloyd", "Seth", "", "MIT" ] ]
quant-ph/9908044
Maria Jose Sanchez
A. J. Fendrik and M. J. S\'anchez
Semiclassical density of degeneracies in quantum regular systems
25 pages, 7 figures . Submitted to PRE
null
10.1088/0305-4470/33/12/303
null
quant-ph
null
The spectrum of eigenenergies of a quantum integrable system whose hamiltonian depends on a single parameter shows degeneracies (crossings) when the parameter varies. We derive a semiclassical expression for the density of crossings in the plane energy-parameter, that is the number of crossings per unit of energy and unit of parameter, in terms of classical periodic orbits. We compare the results of the semiclassical formula with exact quantum calculations for two specific quantum integrable billiards.
[ { "version": "v1", "created": "Fri, 13 Aug 1999 17:40:29 GMT" } ]
2009-10-31T00:00:00
[ [ "Fendrik", "A. J.", "" ], [ "Sánchez", "M. J.", "" ] ]
quant-ph/9908045
Dr P. K. Panigrahi
N. Gurappa, P.S. Mohanty and Prasanta K. Panigrahi
A novel realization of the Calogero-Moser scattering states as coherent states
9 pages, REVTeX
null
10.1103/PhysRevA.61.034703
null
quant-ph cond-mat hep-th
null
A novel realization is provided for the scattering states of the $N$-particle Calogero-Moser Hamiltonian. They are explicitly shown to be the coherent states of the singular oscillators of the Calogero-Sutherland model. Our algebraic treatment is straightforwardly extendable to a large number of few and many-body interacting systems in one and higher dimensions.
[ { "version": "v1", "created": "Fri, 13 Aug 1999 20:36:35 GMT" } ]
2009-10-31T00:00:00
[ [ "Gurappa", "N.", "" ], [ "Mohanty", "P. S.", "" ], [ "Panigrahi", "Prasanta K.", "" ] ]
quant-ph/9908046
Leo Stodolsky
J. Anandan and L. Stodolsky
On the Relation Between Quantum Mechanical and Classical Parallel Transport
3 pages, no figures
Phys. Lett. A 266(2000)95-97
10.1016/S0375-9601(00)00013-X
MPI-PTh/99-34
quant-ph math-ph math.DG math.MP
null
We explain how the kind of ``parallel transport'' of a wavefunction used in discussing the Berry or Geometrical phase induces the conventional parallel transport of certain real vectors. These real vectors are associated with operators whose commutators yield diagonal operators; or in Lie algebras those operators whose commutators are in the (diagonal) Cartan subalgebra.
[ { "version": "v1", "created": "Sat, 14 Aug 1999 12:00:51 GMT" } ]
2009-10-31T00:00:00
[ [ "Anandan", "J.", "" ], [ "Stodolsky", "L.", "" ] ]
quant-ph/9908047
Vlatko Vedral
V. Vedral
On bound entanglement assisted distillation
9 pages, no figures, minor typos corrected
Phys. Lett. A 262 (2-3) 121 (1999)
10.1016/S0375-9601(99)00686-6
null
quant-ph
null
We investigate asymptotic distillation of entanglement in the presence of an unlimited amount of bound entanglement for bi-partite systems. We show that the distillability is still bounded by the relative entropy of entanglement. This offers a strong support to the fact that bound entanglement does not improve distillation of entanglement.
[ { "version": "v1", "created": "Sat, 14 Aug 1999 13:02:56 GMT" }, { "version": "v2", "created": "Wed, 17 Nov 1999 14:49:19 GMT" } ]
2009-10-31T00:00:00
[ [ "Vedral", "V.", "" ] ]
quant-ph/9908048
Michael Martin Nieto
Michael Martin Nieto and D. Rodney Truax
Higher-Power Coherent and Squeezed States
23 pages including 9 figures. To be published in Optics Communications
Optics Com. 179, 197-213 (2000)
10.1016/S0030-4018(99)00483-6
LA-UR-99-1157
quant-ph
null
A closed form expression for the higher-power coherent states (eigenstates of $a^{j}$) is given. The cases j=3,4 are discussed in detail, including the time-evolution of the probability densities. These are compared to the case j=2, the even- and odd-coherent states. We give the extensions to the "effective" displacement-operator, higher-power squeezed states and to the ladder-operator/minimum-uncertainty, higher-power squeezed states. The properties of all these states are discussed.
[ { "version": "v1", "created": "Sun, 15 Aug 1999 01:01:26 GMT" } ]
2016-09-08T00:00:00
[ [ "Nieto", "Michael Martin", "" ], [ "Truax", "D. Rodney", "" ] ]
quant-ph/9908049
Dmitri Horoshko
D. B. Horoshko and S. Ya. Kilin
Quantum Teleportation Using Quantum Non-Demolition Technique
4 pages RevTeX, 2 figures
Phys. Rev. A 61, 032304 (2000)
10.1103/PhysRevA.61.032304
null
quant-ph
null
We propose a new scheme and protocol for quantum teleportation of a single-mode field state, based on entanglement produced by quantum non-demolition interaction. We show that the recently attained results in QND technique allow to perform the teleportation in quantum regime. We also show that applying QND coupling to squeezed fields will significantly improve the quality of teleportation for a given degree of squeezing.
[ { "version": "v1", "created": "Sun, 15 Aug 1999 10:50:09 GMT" } ]
2009-10-31T00:00:00
[ [ "Horoshko", "D. B.", "" ], [ "Kilin", "S. Ya.", "" ] ]
quant-ph/9908050
Robert B. Lockhart
Robert B.Lockhart
Optimal Ensemble Length of Mixed Separable States
8 pages
null
10.1063/1.1290055
null
quant-ph
null
The optimal (pure state) ensemble length of a separable state, A, is the minimum number of (pure) product states needed in convex combination to construct A. We study the set of all separable states with optimal (pure state) ensemble length equal to k or fewer. Lower bounds on k are found below which these sets have measure 0 in the set of separable states. In the bipartite case and the multiparticle case where one of the particles has significantly more quantum numbers than the rest, the lower bound for non-pure state ensembles is sharp. A consequence of our results is that for all two particle systems, except possibly those with a qubit or those with a nine dimensional Hilbert space, and for all systems with more than two particles the optimal pure state ensemble length for a randomly picked separable state is with probability 1 greater than the state's rank. In bipartite systems with probability 1 it is greater than 1/4 the rank raised to the 3/2 power and in a system with p qubits with probability 1 it is greater than (2^2p)/(1+2p), which is almost the square of the rank.
[ { "version": "v1", "created": "Sun, 15 Aug 1999 18:29:05 GMT" } ]
2015-06-26T00:00:00
[ [ "Lockhart", "Robert B.", "" ] ]
quant-ph/9908051
Emanuel Knill
E. Knill, R. Laflamme, R. Martinez, C.-H. Tseng
A Cat-State Benchmark on a Seven Bit Quantum Computer
6 pages with figures
null
null
null
quant-ph
null
We propose and experimentally realize an algorithmic benchmark that demonstrates coherent control with a sequence of quantum operations that first generates and then decodes the cat state (|000...>+|111...>)/sqrt(2) to the standard initial state |000...>. This is the first high fidelity experimental quantum algorithm on the currently largest physical quantum register, which has seven quantum bits (qubits) provided by the nuclei of crotonic acid. The experiment has the additional benefit of verifying a seven coherence in a generic system of coupled spins. Our implementation combines numerous nuclear magnetic resonance (NMR) techniques in one experiment and introduces practical methods for translating quantum networks to control operations. The experimental procedure can be used as a reliable and efficient method for creating a standard pseudo-pure state, the first step for implementing traditional quantum algorithms in liquid state NMR. The benchmark and the techniques can be adapted for use on other proposed quantum devices.
[ { "version": "v1", "created": "Sun, 15 Aug 1999 20:52:42 GMT" } ]
2007-05-23T00:00:00
[ [ "Knill", "E.", "" ], [ "Laflamme", "R.", "" ], [ "Martinez", "R.", "" ], [ "Tseng", "C. -H.", "" ] ]
quant-ph/9908052
Jaehyun Kim
Jaehyun Kim, Jae-Seung Lee, and Soonchil Lee
Implementing unitary operators in quantum computation
published version, 4 pages, 1 figure, REVTeX
Phys. Rev. A 61 (2000) 032312
10.1103/PhysRevA.61.032312
null
quant-ph
null
We present a general method which expresses a unitary operator by the product of operators allowed by the Hamiltonian of spin-1/2 systems. In this method, the generator of an operator is found first, and then the generator is expanded by the base operators of the product operator formalism. Finally, the base operators disallowed by the Hamiltonian, including more than two-body interaction operators, are replaced by allowed ones by the axes transformation and coupling order reduction technique. This method directly provides pulse sequences for the nuclear magnetic resonance quantum computer, and can be generally applied to other systems.
[ { "version": "v1", "created": "Mon, 16 Aug 1999 07:03:34 GMT" }, { "version": "v2", "created": "Sat, 4 Sep 1999 05:24:49 GMT" }, { "version": "v3", "created": "Wed, 16 Feb 2000 03:36:00 GMT" } ]
2009-10-31T00:00:00
[ [ "Kim", "Jaehyun", "" ], [ "Lee", "Jae-Seung", "" ], [ "Lee", "Soonchil", "" ] ]
quant-ph/9908053
Michal Horodecki
Czeslaw Lewa, Pawel Horodecki, Ryszard Horodecki, and Michal Horodecki
MR spectroscopy with parabolic magnetic field: spin-oscillator coupling effect
RevTeX, 3 pages
null
null
null
quant-ph
null
The spectrum of the spin particle in oscillatory potential subjected to external parabolic magnetic field ${\bf B}=(B_0+Gx+\tilde G x^2){\bf \hat z}$ is obtained. The structure of energy levels of the considered system allows to identify the frequency of the oscillator via the spectrum of spin sublevels coming only from {\it one} oscillatory level. The effect is due to the gradient terms in the form of the field.
[ { "version": "v1", "created": "Mon, 16 Aug 1999 12:32:57 GMT" } ]
2007-05-23T00:00:00
[ [ "Lewa", "Czeslaw", "" ], [ "Horodecki", "Pawel", "" ], [ "Horodecki", "Ryszard", "" ], [ "Horodecki", "Michal", "" ] ]
quant-ph/9908054
Shmuel Gurvitz
Brahim Elattari and S.A. Gurvitz
Effect of the measurement on the decay rate of a quantum system
Additional explanations are added. Accepted for publications in Phys. Rev. Lett
Phys.Rev.Lett. 84 (2000) 2047-2051
10.1103/PhysRevLett.84.2047
null
quant-ph cond-mat hep-ph nucl-th
null
We investigated the electron tunneling out of a quantum dot in the presence of a continuous monitoring by a detector. It is shown that the Schr\"odinger equation for the whole system can be reduced to new Bloch-type rate equations describing the time-development of the detector and the measured system at once. Using these equations we find that the continuous measurement of the unstable system does not affect its exponential decay, $\exp (-\Gamma t)$, contrary to expectations based on the Quantum Zeno effect . However, the width of the energy distribution of the tunneling electron is no more $\Gamma$, but increases due to the decoherence, generated by the detector.
[ { "version": "v1", "created": "Mon, 16 Aug 1999 15:47:28 GMT" }, { "version": "v2", "created": "Sun, 2 Jan 2000 08:55:31 GMT" } ]
2009-10-31T00:00:00
[ [ "Elattari", "Brahim", "" ], [ "Gurvitz", "S. A.", "" ] ]
quant-ph/9908055
Sunish Menon
Sunish Menon and G. S. Agarwal
Gain Components in Autler-Townes Doublet from Quantum Interferences in Decay Channels
Total 8 pages, 6 figures, submitted to Physical Review A
null
10.1103/PhysRevA.61.013807
null
quant-ph
null
We consider non-degenerate pump-probe spectroscopy of V-systems under conditions such that interference among decay channels is important. We demonstrate how this interference can result in new gain features instead of the usual absorption features. We relate this gain to the existence of a new vacuum induced quasi-trapped-state. We further show how this also results in large refractive index with low absorption.
[ { "version": "v1", "created": "Mon, 16 Aug 1999 17:47:50 GMT" } ]
2009-10-31T00:00:00
[ [ "Menon", "Sunish", "" ], [ "Agarwal", "G. S.", "" ] ]
quant-ph/9908056
Lu Ming Duan
Lu-Ming Duan, G. Giedke, J. I. Cirac, P. Zoller
Inseparability criterion for continuous variable systems
minor changes in the introduction and refs
Phys. Rev. Lett. 84, 2722 (2000)
10.1103/PhysRevLett.84.2722
null
quant-ph
null
An inseparability criterion based on the total variance of a pair of Einstein-Podolsky-Rosen type operators is proposed for continuous variable systems. The criterion provides a sufficient condition for entanglement of any two-party continuous variable states. Furthermore, for all the Gaussian states, this criterion turns out to be a necessary and sufficient condition for inseparability.
[ { "version": "v1", "created": "Tue, 17 Aug 1999 08:13:31 GMT" }, { "version": "v2", "created": "Fri, 24 Mar 2000 14:05:24 GMT" } ]
2009-10-31T00:00:00
[ [ "Duan", "Lu-Ming", "" ], [ "Giedke", "G.", "" ], [ "Cirac", "J. I.", "" ], [ "Zoller", "P.", "" ] ]
quant-ph/9908057
Yuri N. Morokov
Yu. N. Morokov
The Schwarz-Hora effect: present-day situation
5 pages, RevTex, 2 PS figures
Proceedings of SPIE, "ICONO'98: Fundamental Aspects of Laser-Matter Interaction and New Nonlinear Optical Materials and Physics of Low-Dimensional Structures", 1999, v. 3734, pp. 34-40
10.1117/12.342384
null
quant-ph
null
The electron-diffraction pattern at a nonfluorescent target was observed by Schwarz under attempts to modulate an electron beam by laser light. The pattern was of the same color as the laser light. The analysis of the literature shows there are the unresolved up to now significant contradictions between the theory and the Schwarz experiments. To resolve these contradictions, the interpretation of the Schwarz-Hora effect is considered, which is a development of the idea formulated by Schwarz and Hora. It is supposed that the interaction of electrons with the laser field inside a thin dielectric film is accompanied not only by the processes of absorption and stimulated emission of photons but also by formation of some metastable electron states in which the captured photons can be transferred with a following emission at the target.
[ { "version": "v1", "created": "Tue, 17 Aug 1999 12:35:15 GMT" } ]
2015-06-26T00:00:00
[ [ "Morokov", "Yu. N.", "" ] ]
quant-ph/9908058
Juergen Reingruber
A. Actor, I. Bender, J. Reingruber
Casimir Effect on a Finite Lattice
Latex, 61 pages, 16 postscript figures
Fortsch.Phys. 48 (2000) 303-359
10.1002/(SICI)1521-3978(200004)48:4<303::AID-PROP303>3.0.CO;2-J
null
quant-ph
null
This article presents a Hamiltonian lattice formulation of static Casimir systems at a level of generality appropriate for an introductory investigation. Background structure - represented by a lattice potential V(x) - is introduced along one spatial direction with translation invariance in all other spatial directions. Following some general analysis two specific finite one dimensional lattice QFT systems are analyzed in detail.
[ { "version": "v1", "created": "Tue, 17 Aug 1999 15:43:58 GMT" } ]
2017-04-26T00:00:00
[ [ "Actor", "A.", "" ], [ "Bender", "I.", "" ], [ "Reingruber", "J.", "" ] ]
quant-ph/9908059
Michael Martin Nieto
Michael Martin Nieto
Electrons above a Helium Surface and the One-Dimensional Rydberg Atom
9 pages. Additional material to address the referee's comments
Phys. Rev. A 61, No. 0344901 (2000) 4 pp.
10.1103/PhysRevA.61.034901
LA-UR-99-4097
quant-ph cond-mat
null
Isolated electrons resting above a helium surface are predicted to have a bound spectrum corresponding to a one-dimensional hydrogen atom. But in fact, the observed spectrum is closer to that of a quantum-defect atom. Such a model is discussed and solved in analytic closed form.
[ { "version": "v1", "created": "Tue, 17 Aug 1999 20:26:17 GMT" }, { "version": "v2", "created": "Wed, 17 Nov 1999 05:30:25 GMT" } ]
2009-10-31T00:00:00
[ [ "Nieto", "Michael Martin", "" ] ]
quant-ph/9908060
Chiao
Raymond Y. Chiao
Bogoliubov dispersion relation for a "photon fluid": Is this a superfluid?
11 pages, 4 figures, Scully Festschrift paper to appear in Optics Communications
null
10.1016/S0030-4018(99)00615-X
null
quant-ph cond-mat.stat-mech
null
We discuss the possibility that photons, which are bosons, can form a 2D superfluid due to Bose-Einstein condensation inside a nonlinear Fabry-Perot cavity filled with atoms in their ground states. A "photon fluid" forms inside the cavity as a result of multiple photon-photon collisions mediated by the atoms during a cavity ring-down time. The effective mass and chemical potential for a photon inside this fluid are nonvanishing. This implies the existence of a Bogoliubov dispersion relation for the low-lying elementary excitations of the photon fluid, and in particular, that sound waves exist for long-wavelength, low-frequency disturbances of this fluid. Possible experiments to test for the superfluidity of the photon fluid based on the Landau critical-velocity criterion will be discussed.
[ { "version": "v1", "created": "Wed, 18 Aug 1999 00:10:24 GMT" } ]
2009-10-31T00:00:00
[ [ "Chiao", "Raymond Y.", "" ] ]
quant-ph/9908061
Scutaru Horia
Horia Scutaru
Transition probabilities between quasifree states
13 pages, REVTeX, no figures
Journal of Mathematical Physics, 39, 6403 (1998)
10.1063/1.532656
null
quant-ph
null
We obtain a general formula for the transition probabilities between any state of the algebra of the canonical commutation relations (CCR-algebra) and a squeezed quasifree state. Applications of this formula are made for the case of multimode thermal squeezed states of quantum optics using a general canonical decomposition of the correlation matrix valid for any quasifree state. In the particular case of a one mode CCR-algebra we show that the transition probability between two quasifree squeezed states is a decreasing function of the geodesic distance between the points of the upper half plane representing these states. In the special case of the purification map it is shown that the transition probability between the state of the enlarged system and the product state of real and fictitious subsystems can be a measure for the entanglement.
[ { "version": "v1", "created": "Wed, 18 Aug 1999 08:43:55 GMT" } ]
2009-10-31T00:00:00
[ [ "Scutaru", "Horia", "" ] ]
quant-ph/9908062
Shasanka Mohan Roy
S.M. Roy (Tata Institute of Fundamental Research)
Contextual Deterministic Quantum Mechanics
7 pages,latex,no figs
Int.J.Mod.Phys.B14:2075-2082,2000
10.1142/S0217979200001217
TIFR/TH/99-40
quant-ph gr-qc hep-th
null
We present a simple proof of quantum contextuality for a spinless particle with a one dimensional configuration space. We then discuss how the maximally realistic deterministic quantum mechanics recently constructed by this author and V. Singh can be applied to different contexts.
[ { "version": "v1", "created": "Wed, 18 Aug 1999 13:11:38 GMT" } ]
2011-04-15T00:00:00
[ [ "Roy", "S. M.", "", "Tata Institute of Fundamental Research" ] ]
quant-ph/9908063
Mensky c/o Hellwig
Michael B. Mensky
Quantum Zeno effect in the decay onto an unstable level
9 pages, LATEX
Physics Letters A 257, 227-231 (1999)
10.1016/S0375-9601(99)00290-X
null
quant-ph
null
Under certain assumptions it is shown that the decay of level 2 of a three-level system onto level 1 is slowed down because of the further decay of level 1 onto level 0. It is argued that this phenomenon may be interpreted as a consequence of the quantum Zeno effect. The reason why this may be possible is that the second decay (or accompanying photon radiation) may be considered as a sign of the transition 2 -> 1 so that during the first transition the system is under continuous observation.
[ { "version": "v1", "created": "Wed, 18 Aug 1999 18:22:41 GMT" } ]
2009-10-31T00:00:00
[ [ "Mensky", "Michael B.", "" ] ]
quant-ph/9908064
Dr. Daniel A. Lidar
Daniel A. Lidar, Dave Bacon, Julia Kempe and K.B. Whaley (UC Berkeley)
Decoherence-Free Subspaces for Multiple-Qubit Errors: (I) Characterization
18 pages, no figures. Major changes. Section on universal fault tolerant computation removed. This section contained a crucial error. A new paper [quant-ph/0007013] presents the correct analysis
Phys. Rev. A 63, 022306 (2001)
10.1103/PhysRevA.63.022306
null
quant-ph
null
Coherence in an open quantum system is degraded through its interaction with a bath. This decoherence can be avoided by restricting the dynamics of the system to special decoherence-free subspaces. These subspaces are usually constructed under the assumption of spatially symmetric system-bath coupling. Here we show that decoherence-free subspaces may appear without spatial symmetry. Instead, we consider a model of system-bath interactions in which to first order only multiple-qubit coupling to the bath is present, with single-qubit system-bath coupling absent. We derive necessary and sufficient conditions for the appearance of decoherence-free states in this model, and give a number of examples. In a sequel paper we show how to perform universal and fault tolerant quantum computation on the decoherence-free subspaces considered in this paper.
[ { "version": "v1", "created": "Thu, 19 Aug 1999 01:28:58 GMT" }, { "version": "v2", "created": "Wed, 5 Jul 2000 21:37:16 GMT" } ]
2016-09-08T00:00:00
[ [ "Lidar", "Daniel A.", "", "UC Berkeley" ], [ "Bacon", "Dave", "", "UC Berkeley" ], [ "Kempe", "Julia", "", "UC Berkeley" ], [ "Whaley", "K. B.", "", "UC Berkeley" ] ]
quant-ph/9908065
Michal Horodecki
Michal Horodecki, Pawel Horodecki, and Ryszard Horodecki
Limits for entanglement measures
4 pages, Revtex, typos corrected
Phys. Rev. Lett. 84 (2000) 2014
10.1103/PhysRevLett.84.2014
null
quant-ph
null
We show that {\it any} entanglement measure $E$ suitable for the regime of high number of entangled pairs satisfies $E_D\leq E\leq E_F$ where $E_D$ and $E_F$ are entanglement of distillation and formation respectively. We also exhibit a general theorem on bounds for distillable entanglement. The results are obtained by use of a very transparent reasoning based on the fundamental principle of entanglement theory saying that entanglement cannot increase under local operations and classical communication.
[ { "version": "v1", "created": "Thu, 19 Aug 1999 20:05:08 GMT" }, { "version": "v2", "created": "Wed, 1 Mar 2000 10:12:49 GMT" } ]
2009-10-31T00:00:00
[ [ "Horodecki", "Michal", "" ], [ "Horodecki", "Pawel", "" ], [ "Horodecki", "Ryszard", "" ] ]
quant-ph/9908066
Emanuel Knill
Emanuel Knill, Raymond Laflamme, Lorenza Viola
Theory of Quantum Error Correction for General Noise
6 pages
null
null
null
quant-ph
null
Quantum error correction protects quantum information against environmental noise. When using qubits, a measure of quality of a code is the maximum number of errors that it is able to correct. We show that a suitable notion of ``number of errors'' e makes sense for any system in the presence of arbitrary environmental interactions. In fact, the notion is directly related to the lowest order in time with which uncorrectable errors are introduced, and this in turn is derived from a grading of the algebra generated by the interaction operators. As a result, e-error-correcting codes are effective at protecting quantum information without requiring the usual assumptions of independence and lack of correlation. We prove the existence of large codes for both quantum and classical information. By viewing error-correcting codes as subsystems, we relate codes to irreducible representations of certain operator algebras and show that noiseless subsystems are infinite-distance error-correcting codes. An explicit example involving collective interactions is discussed.
[ { "version": "v1", "created": "Thu, 19 Aug 1999 22:43:44 GMT" } ]
2007-05-23T00:00:00
[ [ "Knill", "Emanuel", "" ], [ "Laflamme", "Raymond", "" ], [ "Viola", "Lorenza", "" ] ]
quant-ph/9908067
Liu
X.M.Liu and G.J.Milburn
Two dimensional nonlinear dynamics of evanescent-wave guiding atoms in hollow fiber
14 pages, 9 figures
null
null
null
quant-ph
null
This paper has been withdrawn due to same as quant-ph/9908068
[ { "version": "v1", "created": "Fri, 20 Aug 1999 01:36:57 GMT" }, { "version": "v2", "created": "Tue, 18 Jan 2000 07:35:53 GMT" } ]
2007-05-23T00:00:00
[ [ "Liu", "X. M.", "" ], [ "Milburn", "G. J.", "" ] ]
quant-ph/9908068
Liu
X. M. Liu and G. J. Milburn
Two dimensional nonlinear dynamics of evanescent-wave guided atoms in hollow fiber
14pages, 9 figures
null
10.1103/PhysRevA.61.053401
null
quant-ph
null
We describe the classical and quantum two dimensional nonlinear dynamics of large blue-detuned eveanescent-wave guiding cold atoms in hollow fiber. We show that chaotic dynamics exists for classic dynamics, when the intensity of the beam is periodically modulated. The two dimensional distributions of atoms in (x,y) plane are simulated. We show that the atoms will accumulate on several annular regions when the system enters a regime of global chaos. Our simulation shows that, when the atomic flux is very small, a similar distribution will be obtained if we detect the atomic distribution once each the modualtion period and integrate the signals. For quantum dynamics, quantum collapses and revivals appear . For periodically modulated optical potential, the variance of atomic position will be supressed compared to the no modulation case. The atomic angular momentum will influnce the evolution of wave function in two dimensional quantum system of hollow fiber.
[ { "version": "v1", "created": "Fri, 20 Aug 1999 01:50:51 GMT" }, { "version": "v2", "created": "Sun, 26 Dec 1999 12:00:47 GMT" } ]
2009-10-31T00:00:00
[ [ "Liu", "X. M.", "" ], [ "Milburn", "G. J.", "" ] ]
quant-ph/9908069
Alvaro L.
R. P. Mart\'inez-y-Romero, H. N. N\'u\~nez-Y\'epez, A. L. Salas-Brito
Relativistic quantum mechanics of a Dirac oscillator
19 pages, 1 figure
Eur.J.Phys.16:135-141,1995
10.1088/0143-0807/16/3/008
null
quant-ph math-ph math.MP physics.ed-ph
null
The Dirac oscillator is an exactly soluble model recently introduced in the context of many particle models in relativistic quantum mechanics. The model has been also considered as an interaction term for modelling quark confinement in quantum chromodynamics. These considerations should be enough for demonstrating that the Dirac oscillator can be an excellent example in relativistic quantum mechanics. In this paper we offer a solution to the problem and discuss some of its properties. We also discuss a physical picture for the Dirac oscillator's non-standard interaction, showing how it arises on describing the behaviour of a neutral particle carrying an anomalous magnetic moment and moving inside an uniformly charged sphere.
[ { "version": "v1", "created": "Sat, 21 Aug 1999 05:11:50 GMT" } ]
2016-08-15T00:00:00
[ [ "Martínez-y-Romero", "R. P.", "" ], [ "Núñez-Yépez", "H. N.", "" ], [ "Salas-Brito", "A. L.", "" ] ]
quant-ph/9908070
Barbara M. Terhal
David P. DiVincenzo, Tal Mor, Peter W. Shor, John A. Smolin and Barbara M. Terhal
Unextendible Product Bases, Uncompletable Product Bases and Bound Entanglement
24 pages RevTex, 15 figures; appendix removed, several small corrections, to appear in Comm. Math. Phys
Comm. Math. Phys. 238, pp. 379--410 (2003)
10.1007/s00220-003-0877-6
null
quant-ph
null
We report new results and generalizations of our work on unextendible product bases (UPB), uncompletable product bases and bound entanglement. We present a new construction for bound entangled states based on product bases which are only completable in a locally extended Hilbert space. We introduce a very useful representation of a product basis, an orthogonality graph. Using this representation we give a complete characterization of unextendible product bases for two qutrits. We present several generalizations of UPBs to arbitrary high dimensions and multipartite systems. We present a sufficient condition for sets of orthogonal product states to be distinguishable by separable superoperators. We prove that bound entangled states cannot help increase the distillable entanglement of a state beyond its regularized entanglement of formation assisted by bound entanglement.
[ { "version": "v1", "created": "Sun, 22 Aug 1999 17:00:55 GMT" }, { "version": "v2", "created": "Fri, 12 Nov 1999 20:04:25 GMT" }, { "version": "v3", "created": "Mon, 6 Nov 2000 15:51:51 GMT" } ]
2007-05-23T00:00:00
[ [ "DiVincenzo", "David P.", "" ], [ "Mor", "Tal", "" ], [ "Shor", "Peter W.", "" ], [ "Smolin", "John A.", "" ], [ "Terhal", "Barbara M.", "" ] ]
quant-ph/9908071
Arnold Neumaier
Arnold Neumaier
On a realistic interpretation of quantum mechanics
21 pages
null
null
null
quant-ph
null
The best mathematical arguments against a realistic interpretation of quantum mechanics - that gives definite but partially unknown values to all observables - are analysed and shown to be based on reasoning that is not compelling. This opens the door for an interpretation that, while respecting the indeterministic nature of quantum mechanics, allows to speak of definite values for all observables at any time that are, however, only partially measurable. The analysis also suggests new ways to test the foundations of quantum theory.
[ { "version": "v1", "created": "Sun, 22 Aug 1999 20:39:52 GMT" } ]
2007-05-23T00:00:00
[ [ "Neumaier", "Arnold", "" ] ]
quant-ph/9908072
Paul G. Kwiat
Peter D. D. Schwindt (1), Paul G. Kwiat (1), and Berthold-Georg Englert (2) ((1) Physics Div., Los Alamos National Laboratory, (2) Max-Planck-Institute fuer Quantenoptik)
Quantitative wave-particle duality and non-erasing quantum erasure
6 pages, 4 figures. To appear in Phys. Rev. A
null
10.1103/PhysRevA.60.4285
LA-UR-98-5653
quant-ph
null
The notion of wave-particle duality may be quantified by the inequality V^2+K^2 <=1, relating interference fringe visibility V and path knowledge K. With a single-photon interferometer in which polarization is used to label the paths, we have investigated the relation for various situations, including pure, mixed, and partially-mixed input states. A quantum eraser scheme has been realized that recovers interference fringes even when no which-way information is available to erase.
[ { "version": "v1", "created": "Mon, 23 Aug 1999 23:28:07 GMT" } ]
2009-10-31T00:00:00
[ [ "Schwindt", "Peter D. D.", "" ], [ "Kwiat", "Paul G.", "" ], [ "Englert", "Berthold-Georg", "" ] ]
quant-ph/9908073
Charles H. Bennett
Charles H. Bennett, Sandu Popescu, Daniel Rohrlich, John A. Smolin, and Ashish V. Thapliyal
Exact and Asymptotic Measures of Multipartite Pure State Entanglement
13 pages including 3 PostScript figures. v3 has updated references and discussion, to appear Phys. Rev. A
null
10.1103/PhysRevA.63.012307
null
quant-ph
null
In an effort to simplify the classification of pure entangled states of multi (m) -partite quantum systems, we study exactly and asymptotically (in n) reversible transformations among n'th tensor powers of such states (ie n copies of the state shared among the same m parties) under local quantum operations and classical communication (LOCC). With regard to exact transformations, we show that two states whose 1-party entropies agree are either locally-unitarily (LU) equivalent or else LOCC-incomparable. In particular we show that two tripartite Greenberger-Horne-Zeilinger (GHZ) states are LOCC-incomparable to three bipartite Einstein-Podolsky-Rosen (EPR) states symmetrically shared among the three parties. Asymptotic transformations result in a simpler classification than exact transformations. We show that m-partite pure states having an m-way Schmidt decomposition are simply parameterizable, with the partial entropy across any nontrivial partition representing the number of standard ``Cat'' states (|0^m>+|1^m>) asymptotically interconvertible to the state in question. For general m-partite states, partial entropies across different partitions need not be equal, and since partial entropies are conserved by asymptotically reversible LOCC operations, a multicomponent entanglement measure is needed, with each scalar component representing a different kind of entanglement, not asymptotically interconvertible to the other kinds. In particular the m=4 Cat state is not isentropic to, and therefore not asymptotically interconvertible to, any combination of bipartite and tripartite states shared among the four parties. Thus, although the m=4 cat state can be prepared from bipartite EPR states, the preparation process is necessarily irreversible, and remains so even asymptotically.
[ { "version": "v1", "created": "Tue, 24 Aug 1999 03:24:32 GMT" }, { "version": "v2", "created": "Mon, 27 Dec 1999 20:20:05 GMT" }, { "version": "v3", "created": "Sun, 25 Jun 2000 22:36:36 GMT" } ]
2021-05-26T00:00:00
[ [ "Bennett", "Charles H.", "" ], [ "Popescu", "Sandu", "" ], [ "Rohrlich", "Daniel", "" ], [ "Smolin", "John A.", "" ], [ "Thapliyal", "Ashish V.", "" ] ]
quant-ph/9908074
Yu Shi
Yu Shi
Remarks on Universal Quantum Computer
revtex, 14 pages, version appearing in Phys. Lett. A
Phys. Lett. A 293 (2002) 277
10.1016/S0375-9601(02)00015-4
null
quant-ph
null
According to Deutsch, a universal quantum Turing machine (UQTM) is able to perform, in repeating a fixed unitary transformation on the total system, an arbitrary unitary transformation on an arbitrary data state, by including a program as another part of the input state. We note that if such a UQTM really exists, with the program state dependent on the data state, and if the prescribed halting scheme is indeed valid, then there would be no entanglement between the halt qubit and other qubits, as pointed out by Myers. If, however, the program is required to be independent of the data, the concerned entanglement appears, and is problematic no matter whether the halt qubit is monitored or not. We also note that for a deterministic programmable quantum gate array, as discussed by Nielson and Chuang, if the program is allowed to depend on the data state, then its existence has not been ruled out. On the other hand, if UQTM exists, it can be simulated by repeating the operation of a fixed gate array. However, more importantly, we observe that it is actually still open whether Deutsch's UQTM exists and whether a crucial concatenation scheme, of which the halting scheme is a special case, is valid.
[ { "version": "v1", "created": "Tue, 24 Aug 1999 10:00:29 GMT" }, { "version": "v2", "created": "Sun, 5 Sep 1999 22:34:22 GMT" }, { "version": "v3", "created": "Sat, 9 Oct 1999 13:15:25 GMT" }, { "version": "v4", "created": "Tue, 8 Feb 2000 09:59:20 GMT" }, { "version": "v5", "created": "Sun, 20 Jan 2002 23:02:20 GMT" } ]
2009-10-31T00:00:00
[ [ "Shi", "Yu", "" ] ]
quant-ph/9908075
Inge S. Helland
Inge S. Helland
Quantum Mechanics from Symmetry and Statistical Modelling
The paper has been withdrawn because it is outdated
null
null
null
quant-ph
null
A version of quantum theory is derived from a set of plausible assumptions related to the following general setting: For a given system there is a set of experiments that can be performed, and for each such experiment an ordinary statistical model is defined. The parameters of the single experiments are functions of a hyperparameter, which defines the state of the system. There is a symmetry group acting on the hyperparameters, and for the induced action on the parameters of the single experiment a simple consistency property is assumed, called permissibility of the parametric function. The other assumptions needed are rather weak. The derivation relies partly on quantum logic, partly on a group representation of the hyperparameter group, where the invariant spaces are shown to be in 1-1 correspondence with the equivalence classes of permissible parametric functions. Planck's constant only plays a role connected to generators of unitary group representations.
[ { "version": "v1", "created": "Tue, 24 Aug 1999 11:22:17 GMT" }, { "version": "v2", "created": "Sat, 7 Jul 2012 09:56:42 GMT" } ]
2012-07-10T00:00:00
[ [ "Helland", "Inge S.", "" ] ]
quant-ph/9908076
Inge S. Helland
Inge S. Helland
Quantum Theory from Symmetries in a General Statistical Parameter Space
The paper has been withdrawn because it is outdated
null
null
null
quant-ph
null
The aim of this paper is to show a connection between an extended theory of statistical experiments on the one hand and the foundation of quantum theory on the other hand. The main aspects of this extension are: One assumes a hyperparameter space $\Phi$ common to several potential experiments, and a basic symmetry group G associated with this space. The parameter \theta_{a} of a single experiment, looked upon as a parametric function $\theta_{a}(\cdot)$ on $\Phi$, is said to be permissible if G induces in a natural way a new group on the image space of the function. If this is not the case, it is arranged for by changing from G to a subgroup $G_{a}$. The Haar measure of this subgroup (confined to the spectrum; see below) is the prefered prior when the parameter is unknown. It is assumed that the hyperparameter itself can never be estimated, only a set of parametric functions. Model reduction is made by restricting the space of complex `wave' functions, also regarded as functions on $\Phi$, to an irreducible invariant subspace $\mathcal{M}$ under G. The spectrum of a parametric function is defined from natural group-theoretical and statistical considerations. We establish that a unique operator can be associated with every parametric functions $\theta_{a}(\cdot)$, and essentially all of the ordinary quantum theory formalism can be retrieved from these and a few related assumptions. In particular the concept of spectrum is consistent. The scope of the theory is illustrated on the one hand by the example of a spin 1/2 particle and a related EPR discussion, on the other hand by a simple macroscopic example.
[ { "version": "v1", "created": "Tue, 24 Aug 1999 11:30:59 GMT" }, { "version": "v2", "created": "Sat, 7 Jul 2012 09:55:43 GMT" } ]
2012-07-10T00:00:00
[ [ "Helland", "Inge S.", "" ] ]
quant-ph/9908077
Richard A. Mould
Richard A. Mould
Quantum Consciousness
12 pages, 5 figures
null
null
null
quant-ph
null
In a previous paper, the author proposed a quantum mechanical interaction that would insure that the evolution of subjective states would parallel the evolution of biological states, as required by von Neumann's theory of measurement. The particular model for this interaction suggested an experiment that the author has now performed wih negative results. A modified model is outlined in this paper that preserves the desirable features of the original model, and is consistent with the experimental results. This model will be more difficult to verify. However, some strategies are suggested.
[ { "version": "v1", "created": "Tue, 24 Aug 1999 18:07:09 GMT" } ]
2007-05-23T00:00:00
[ [ "Mould", "Richard A.", "" ] ]
quant-ph/9908078
Mike York
Michael J. York
Identity, Geometry, Permutation And The Spin-Statistics Theorem
This version includes revisions to the abstract, introduction and other explanatory text. In particular, we give more attention to explaining the short-comings of the conventional symmetrization postulate
null
null
null
quant-ph hep-th physics.ed-ph
null
We examine historic formulations of the spin-statistics theorem from a point of view that distinguishes between the observable consequences and the ``symmetrization postulate''. In particular, we make a critical analysis of concepts of particle identity, state distinguishability and permutation, and particle ``labels''. We discuss how to construct unique state vectors and the nature of the full state descriptions required for this -- in particular the elimination of arbitrary $2\pi$ rotations on fermion spin quantization frames and argue that the failure to do this renders the conventional symmetrization postulate (and previous ``proofs'' of it) at best {\em incomplete}. We discuss particle permutation in a general way for any pairs of particles, whether identical or not, and make an essential distinction between exchange and pure permutation. We prove a revised symmetrization postulate that allows us to construct state vectors that are naturally symmetric under pure permutation, {\em for any spin}. The significance of particle labels (which, in the exchange operation, are not permuted along with other variables) is then that they stand in for any asymmetry (order dependence) that is present in the full state descriptions necessary for unique state vectors but not explicit in the regular state variables. {\em The exchange operation is then the physical transformation that reverses any asymmetry implicit in the labels}. We point out a previously unremarked geometrical asymmetry between all pairs of particles that is present whenever we choose a common frame of reference. We compute the exchange phase for various state vectors using different spin quantization frames, and prove the Pauli Exclusion Principle and its generalization to arbitrary spin.
[ { "version": "v1", "created": "Wed, 25 Aug 1999 02:57:44 GMT" }, { "version": "v2", "created": "Mon, 15 Nov 1999 02:47:59 GMT" } ]
2007-05-23T00:00:00
[ [ "York", "Michael J.", "" ] ]
quant-ph/9908079
Martin Bojowald
Martin Bojowald and Thomas Strobl
Group Theoretical Quantization and the Example of a Phase Space S^1 x R^+
41 pages, LaTeX2e
J.Math.Phys. 41 (2000) 2537-2567
10.1063/1.533258
PITHA 99/25, ESI 742
quant-ph gr-qc hep-th
null
The group theoretical quantization scheme is reconsidered by means of elementary systems. Already the quantization of a particle on a circle shows that the standard procedure has to be supplemented by an additional condition on the admissibility of group actions. A systematic strategy for finding admissible group actions for particular subbundles of cotangent spaces is developed, two-dimensional prototypes of which are T^*R^+ and S^1 x R^+ (interpreted as restrictions of T^*R and T^*S^1 to positive coordinate and momentum, respectively). In this framework (and under an additional, natural condition) an SO_+(1,2)-action on S^1 x R^+ results as the unique admissible group action. For symplectic manifolds which are (specific) parts of phase spaces with known quantum theory a simple projection method of quantization is formulated. For T^*R^+ and S^1 x R^+ equivalent results to those of more established (but more involved) quantization schemes are obtained. The approach may be of interest, e.g., in attempts to quantize gravity theories where demanding nondegenerate metrics of a fixed signature imposes similar constraints.
[ { "version": "v1", "created": "Fri, 27 Aug 1999 13:51:07 GMT" }, { "version": "v2", "created": "Mon, 13 Dec 1999 13:33:43 GMT" } ]
2016-09-08T00:00:00
[ [ "Bojowald", "Martin", "" ], [ "Strobl", "Thomas", "" ] ]
quant-ph/9908080
Thomas L. Clarke
Thomas L. Clarke
A Quantum NP Solver: NP in QP
Withdrawn by author because the Bk operators were non-unitary and
null
null
null
quant-ph
null
A attempt at a quantum algorithm for solving NP problems is presented. Now withdrawn because some crucial operators were not unitary.
[ { "version": "v1", "created": "Fri, 27 Aug 1999 17:56:19 GMT" }, { "version": "v2", "created": "Mon, 30 Aug 1999 19:54:15 GMT" } ]
2012-01-19T00:00:00
[ [ "Clarke", "Thomas L.", "" ] ]
quant-ph/9908081
Andrew G. White
Andrew G. White (1), Daniel F. V. James (2), Philippe H. Eberhard (3) and Paul G. Kwiat (1) ((1) Physics Division, P-23; (2) Theoretical Division, T-4; Los Alamos National Laboratory. (3) Lawrence Berkeley Laboratory, University of California.)
Non-maximally entangled states: production, characterization and utilization
4 pages, 4 figures. To appear in Phys. Rev. Lett
Physical Review Letters 83, no. 16, pp. 3103-3107 (1999)
10.1103/PhysRevLett.83.3103
LAUR 99-3196
quant-ph
null
Using a spontaneous-downconversion photon source, we produce true non-maximally entangled states, i.e., without the need for post-selection. The degree and phase of entanglement are readily tunable, and are characterized both by a standard analysis using coincidence minima, and by quantum state tomography of the two-photon state. Using the latter, we experimentally reconstruct the reduced density matrix for the polarization. Finally, we use these states to measure the Hardy fraction, obtaining a result that is $122 \sigma$ from any local-realistic result.
[ { "version": "v1", "created": "Fri, 27 Aug 1999 20:11:21 GMT" } ]
2009-10-31T00:00:00
[ [ "White", "Andrew G.", "" ], [ "James", "Daniel F. V.", "" ], [ "Eberhard", "Philippe H.", "" ], [ "Kwiat", "Paul G.", "" ] ]
quant-ph/9908082
Steven J. van Enk
S.J. van Enk and H.J. Kimble
A single atom in free space as a quantum aperture
4 pages ReVTeX and 3 eps figures
null
10.1103/PhysRevA.61.051802
null
quant-ph
null
We calculate exact 3-D solutions of Maxwell equations corresponding to strongly focused light beams, and study their interaction with a single atom in free space. We show how the naive picture of the atom as an absorber with a size given by its radiative cross section $\sigma =3\lambda ^{2}/2\pi $ must be modified. The implications of these results for quantum information processing capabilities of trapped atoms are discussed.
[ { "version": "v1", "created": "Fri, 27 Aug 1999 21:57:43 GMT" } ]
2009-10-31T00:00:00
[ [ "van Enk", "S. J.", "" ], [ "Kimble", "H. J.", "" ] ]
quant-ph/9908083
Daniel S. Abrams
Daniel S. Abrams and Colin P. Williams
Fast quantum algorithms for numerical integrals and stochastic processes
null
null
null
null
quant-ph
null
We discuss quantum algorithms that calculate numerical integrals and descriptive statistics of stochastic processes. With either of two distinct approaches, one obtains an exponential speed increase in comparison to the fastest known classical deterministic algorithms and a quadratic speed increase in comparison to classical Monte Carlo (probabilistic) methods. We derive a simpler and slightly faster version of Grover's mean algorithm, demonstrate how to apply quantum counting to the problem, develop some variations of these algorithms, and show how both (apparently quite different) approaches can be understood from the same unified framework. Finally, we discuss how the exponential speed increase appears to (but does not) violate results obtained via the method of polynomials, from which it is known that a bounded-error quantum algorithm for computing a total function can be only polynomially more efficient than the fastest deterministic classical algorithm.
[ { "version": "v1", "created": "Sat, 28 Aug 1999 00:40:19 GMT" } ]
2007-05-23T00:00:00
[ [ "Abrams", "Daniel S.", "" ], [ "Williams", "Colin P.", "" ] ]
quant-ph/9908084
H. Dieter Zeh
H. D. Zeh
The Problem of Conscious Observation in Quantum Mechanical Description
Published version: new abstract, minor changes, some new references. 14 pages, Latex
Found.Phys.Lett. 13 (2000) 221-233
null
null
quant-ph gr-qc
null
Epistemological consequences of quantum nonlocality (entanglement) are discussed under the assumption of a universally valid Schr\"odinger equation in the absence of hidden variables. This leads inevitably to a {\it many-minds interpretation}. The recent foundation of quasi-classical neural states in the brain (based on environmental decoherence) permits in principle a formal description of the whole chain of measurement interactions, including the {\it behavior} of conscious observers, without introducing any intermediate classical concepts (for macroscopic "pointer states") or "observables" (for microscopic particle positions and the like) --- thus consistently formalizing Einstein's {\it ganzer langer Weg} from the observed to the observer in quantum mechanical terms.
[ { "version": "v1", "created": "Sat, 28 Aug 1999 13:07:31 GMT" }, { "version": "v2", "created": "Fri, 10 Mar 2000 15:17:34 GMT" }, { "version": "v3", "created": "Mon, 5 Jun 2000 11:38:44 GMT" } ]
2007-05-23T00:00:00
[ [ "Zeh", "H. D.", "" ] ]
quant-ph/9908085
null
N.D. Hari Dass (IMSc, Chennai, India)
Cold Atoms For Testing Quantum Mechanics and Parity Violation In Gravitation
Revtex, 8 pages
null
null
null
quant-ph
null
Techniques of Atom trapping and laser cooling have proved to be very important tools in probing many aspects of fundamental physics. In this talk I wish to present ideas on how they may used to settle certain issues in the foundational aspects of quantum mechanics on the one hand and about some quantum gravitational interactions of matter that violate parity and time-reversal, on the other hand.
[ { "version": "v1", "created": "Sat, 28 Aug 1999 16:53:19 GMT" } ]
2007-05-23T00:00:00
[ [ "Dass", "N. D. Hari", "", "IMSc, Chennai, India" ] ]
quant-ph/9908086
Michael Nielsen
M. A. Nielsen
Continuity bounds for entanglement
5 pages, submitted to Physical Review A Brief Reports. Minor typo in equation (25) corrected in resubmission
Physical Review A 61 (6): Art. No. 064301 (2000)
10.1103/PhysRevA.61.064301
null
quant-ph
null
This note quantifies the continuity properties of entanglement: how much does entanglement vary if we change the entangled quantum state just a little? This question is studied for the pure state entanglement of a bipartite system and for the entanglement of formation of a bipartite system in a mixed state.
[ { "version": "v1", "created": "Mon, 30 Aug 1999 01:19:57 GMT" }, { "version": "v2", "created": "Fri, 3 Sep 1999 18:05:29 GMT" } ]
2009-10-31T00:00:00
[ [ "Nielsen", "M. A.", "" ] ]
quant-ph/9908087
Mario Encinosa
M. Encinosa and Ray N. O'Neal, Jr.(Florida A&M University)
Quantum particle constrained to a curved surface in the presence of a vector potential
added author and changed two ambiguous phrases. submitted to Phys. Rev. Lett
null
null
null
quant-ph
null
The Schrodinger equation for a charged particle constrained to a curved surface in the presence of a vector potential is derived using the method of forms. In the limit that the particle is brought infinitesimally close to the surface, a term arises that couples the component of the vector potential normal to the surface to the mean curvature of the surface.
[ { "version": "v1", "created": "Mon, 30 Aug 1999 18:25:01 GMT" }, { "version": "v2", "created": "Thu, 7 Oct 1999 02:57:08 GMT" } ]
2012-08-27T00:00:00
[ [ "Encinosa", "M.", "", "Florida A&M University" ], [ "O'Neal,", "Ray N.", "Jr.", "Florida A&M University" ] ]
quant-ph/9908088
Ricardo Moritz Cavalcanti
R. M. Cavalcanti
Comment on ``Validity of Feynman's prescription of disregarding the Pauli principle in intermediate states''
1 page
Phys. Rev. A 62, 016101 (2000)
10.1103/PhysRevA.62.016101
null
quant-ph
null
In a recent paper Coutinho, Nogami and Tomio [Phys. Rev. A 59, 2624 (1999); quant-ph/9812073] presented an example in which, they claim, Feynman's prescription of disregarding the Pauli principle in intermediate states of perturbation theory fails. We show that, contrary to their claim, Feynman's prescription is consistent with the exact solution of their example.
[ { "version": "v1", "created": "Tue, 31 Aug 1999 01:24:21 GMT" } ]
2009-10-31T00:00:00
[ [ "Cavalcanti", "R. M.", "" ] ]
quant-ph/9908089
Scutaru Horia
Horia Scutaru
A new measure of nonclassical distance
14 pages, LaTeX, IOP journal preprint style, no figures, submitted to Journal of Physics A: Math. Gen., September 1999
null
null
FT-439-September 1999
quant-ph
null
We propose a new measure of the nonclassical distance in the case of Gaussian states. Let us consider two Gaussian states one of which is fixed and the other runs through the set of Gaussian classical states. The maximum value of the fidelity between these two states can be used as a nonclassical distance of the fixed state to the set of classical states, in the same extent as the Hillery measure. This measure increases when on the fixed state acts a Gaussian noise map i.e. the selected state becomes closer to the classical states.
[ { "version": "v1", "created": "Tue, 31 Aug 1999 08:29:08 GMT" } ]
2007-05-23T00:00:00
[ [ "Scutaru", "Horia", "" ] ]
quant-ph/9908090
Gavriel Segre
Gavriel Segre
Computability Superselection Rule and its physical explanation
cross-listing mistake
null
null
null
quant-ph
null
Paper erroneously re-submitted as duplicte. Readers should look at math-ph/9909004.
[ { "version": "v1", "created": "Tue, 31 Aug 1999 20:14:22 GMT" }, { "version": "v2", "created": "Wed, 1 Sep 1999 10:04:21 GMT" }, { "version": "v3", "created": "Sat, 4 Sep 1999 19:56:06 GMT" } ]
2007-05-23T00:00:00
[ [ "Segre", "Gavriel", "" ] ]
quant-ph/9909001
Bonatsos Dennis
Dennis Bonatsos and C. Daskaloyannis
Quantum Algebraic Symmetries in Nuclei, Molecules and Atomic Clusters
18 pages, LateX. Presented at the Balkan School on Nuclear Physics (Istanbul, 1998)
Balkan Phys. Lett., Special Issue (1998) 145-162
null
DEM-NT-98-02
quant-ph
null
Various applications of quantum algebraic techniques in nuclear structure physics and in molecular physics are briefly reviewed and a recent application of these techniques to the structure of atomic clusters is discussed in more detail.
[ { "version": "v1", "created": "Wed, 1 Sep 1999 07:27:48 GMT" } ]
2007-05-23T00:00:00
[ [ "Bonatsos", "Dennis", "" ], [ "Daskaloyannis", "C.", "" ] ]
quant-ph/9909002
Bonatsos Dennis
Dennis Bonatsos, N. Karoussos, P. P. Raychev, R. P. Roussev and P. A. Terziev
The 3-Dimensional q-Deformed Harmonic Oscillator and Magic Numbers of Alkali Metal Clusters
13 pages, LaTeX
Chem. Phys. Lett. 302 (1999) 392-398
10.1016/S0009-2614(99)00199-2
DEM-NT-99-03
quant-ph
null
Magic numbers predicted by a 3-dimensional q-deformed harmonic oscillator with Uq(3) > SOq(3) symmetry are compared to experimental data for alkali metal clusters, as well as to theoretical predictions of jellium models, Woods--Saxon and wine bottle potentials, and to the classification scheme using the 3n+l pseudo quantum number. The 3-dimensional q-deformed harmonic oscillator correctly predicts all experimentally observed magic numbers up to 1500 (which is the expected limit of validity for theories based on the filling of electronic shells), thus indicating that Uq(3), which is a nonlinear extension of the U(3) symmetry of the spherical (3-dimensional isotropic) harmonic oscillator, is a good candidate for being the symmetry of systems of alkali metal clusters.
[ { "version": "v1", "created": "Wed, 1 Sep 1999 07:28:03 GMT" } ]
2009-10-31T00:00:00
[ [ "Bonatsos", "Dennis", "" ], [ "Karoussos", "N.", "" ], [ "Raychev", "P. P.", "" ], [ "Roussev", "R. P.", "" ], [ "Terziev", "P. A.", "" ] ]
quant-ph/9909003
Miloslav Znojil
Miloslav Znojil
Exact solution for Morse oscillator in PT-symmetric quantum mechanics
8 pages, submitted to Phys. Lett. A
Phys. Lett. A 264 (1999) 108-111
10.1016/S0375-9601(99)00805-1
null
quant-ph
null
The recently proposed PT-symmetric quantum mechanics works with complex potentials which possess, roughly speaking, a symmetric real part and an anti-symmetric imaginary part. We propose and describe a new exactly solvable model of this type. It is defined as a specific analytic continuation of the shape-invariant potential of Morse. In contrast to the latter well-known example, all the new spectrum proves real, discrete and bounded below. All its three separate subsequences are quadratic in n.
[ { "version": "v1", "created": "Wed, 1 Sep 1999 12:17:49 GMT" } ]
2009-10-31T00:00:00
[ [ "Znojil", "Miloslav", "" ] ]
quant-ph/9909004
Pinaki Roy
Geza Levai and Pinaki Roy
Conditionally Exactly Solvable Potentials and Supersymmetric Transformations
10 pages,Reference added
null
10.1016/S0375-9601(99)00778-1
null
quant-ph
null
A general procedure is presented to construct conditionally solvable (CES) potentials using the techniques of supersymmetric quantum mechanics.The method is illustrated with potentials related to the harmonic oscillator problem.Besides recovering known results,new CES potentials are also obtained within the framework of this general approach.The conditions under which this method leads to CES potentials are also discussed.
[ { "version": "v1", "created": "Wed, 1 Sep 1999 12:40:58 GMT" }, { "version": "v2", "created": "Wed, 8 Sep 1999 08:38:34 GMT" } ]
2009-10-31T00:00:00
[ [ "Levai", "Geza", "" ], [ "Roy", "Pinaki", "" ] ]
quant-ph/9909005
Anu Venugopalan
Anu Venugopalan
Pointer states via Decoherence in a Quantum Measurement
9 pages, LaTex, communicated to Physical Review A
null
10.1103/PhysRevA.61.012102
null
quant-ph
null
We consider the interaction of a quantum system (spin-1/2) with a macroscopic quantum apparatus (harmonic oscillator) which in turn is coupled to a bath of harmonic oscillators. Exact solutions of the Markovian Master equation show that the reduced density matrix of the system-apparatus combine decoheres to a statistical mixture where up and down spins eventually correlate with pointer states of the apparatus. For the zero temperature bath these pointer states turn out to be coherent states of the harmonic oscillator for arbitrary initial states of the apparatus. For a high temperature bath pointer states are Gaussian distributions (generalized coherent states). For both cases, the off-diagonal elements in spin-space decohere over a time scale which goes inversely as the square of the "separation" between the "pointers". Our exact results also demonstrate in an unambiguous way that the pointer states in this measurement model emerge independent of the initial state of the apparatus.
[ { "version": "v1", "created": "Wed, 1 Sep 1999 17:15:28 GMT" } ]
2009-10-31T00:00:00
[ [ "Venugopalan", "Anu", "" ] ]
quant-ph/9909006
Mark Hillery
Mark Hillery
Quantum cryptography with squeezed states
15 pages, no figures
null
10.1103/PhysRevA.61.022309
null
quant-ph
null
A quantum key distribution scheme based on the use of displaced squeezed vacuum states is presented. The states are squeezed in one of two field quadrature components, and the value of the squeezed component is used to encode a character from an alphabet. The uncertainty relation between quadrature components prevents an eavesdropper from determining both with enough precision to determine the character being sent. Losses degrade the performance of this scheme, but it is possible to use phase-sensitive amplifiers to boost the signal and partially compensate for their effect.
[ { "version": "v1", "created": "Wed, 1 Sep 1999 21:38:32 GMT" } ]
2009-10-31T00:00:00
[ [ "Hillery", "Mark", "" ] ]
quant-ph/9909007
Simon Benjamin
S. C. Benjamin (Univ. of Oxford)
Schemes for Parallel Quantum Computation Without Local Control of Qubits
12 pages + 3 figures. Several small corrections made
null
10.1103/PhysRevA.61.020301
null
quant-ph
null
Typical quantum computing schemes require transformations (gates) to be targeted at specific elements (qubits). In many physical systems, direct targeting is difficult to achieve; an alternative is to encode local gates into globally applied transformations. Here we demonstrate the minimum physical requirements for such an approach: a one-dimensional array composed of two alternating 'types' of two-state system. Each system need be sensitive only to the net state of its nearest neighbors, i.e. the number in state 1 minus the number in state 2. Additionally, we show that all such arrays can perform quite general parallel operations. A broad range of physical systems and interactions are suitable: we highlight two potential implementations.
[ { "version": "v1", "created": "Thu, 2 Sep 1999 18:35:27 GMT" }, { "version": "v2", "created": "Sat, 18 Sep 1999 16:59:24 GMT" } ]
2009-10-31T00:00:00
[ [ "Benjamin", "S. C.", "", "Univ. of Oxford" ] ]
quant-ph/9909008
Alexander A. Kokin
K. A. Valiev and A. A. Kokin (Institute of Physics and Technology, Russian Academy of Sciences)
Solid-state NMR quantum computer with individual access to qubits and some its ensemble developments
LaTex 21 pages, 4 EPS figures; Figure 2 changed
null
null
null
quant-ph
null
Here we made an analysis of the principles of a semiconductor NMR quantum computer and its developments. The known variant of an individual-access computer (B. Kane) and alternative solid-state bulk-ensemble approach versions allowing to avoid some difficulties in implementing the first variant are considered.
[ { "version": "v1", "created": "Thu, 2 Sep 1999 07:37:02 GMT" }, { "version": "v2", "created": "Mon, 15 Nov 1999 16:31:29 GMT" } ]
2007-05-23T00:00:00
[ [ "Valiev", "K. A.", "", "Institute of Physics and Technology,\n Russian Academy of Sciences" ], [ "Kokin", "A. A.", "", "Institute of Physics and Technology,\n Russian Academy of Sciences" ] ]
quant-ph/9909009
W. A. Hofer
W. A. Hofer
On interference: the scalar problem
Six pages (RevTeX) and four figures (eps). For a full list of available papers see http://info.tuwien.ac.at/cms/wh/
null
null
MW-99-03
quant-ph hep-th
null
Single-slit and two-slit interferometer measurements of electrons are analyzed within the realistic model of particle propagation. In a step by step procedure we show that all current models of interference are essentially non-local and demonstrate that the treatment of the quantum theory of motion is the simplest model for the scalar problem. In particular we give a novel interpretation of the quantum potential Q, which should be regarded as a non-classical and essentially statistical term describing the changes of the quantum ensemble due to a change of the physical environment.
[ { "version": "v1", "created": "Thu, 2 Sep 1999 09:35:14 GMT" } ]
2007-05-23T00:00:00
[ [ "Hofer", "W. A.", "" ] ]
quant-ph/9909010
Benni Reznik
Aharon Casher and Benni Reznik
Back-Reaction of Clocks and Limitations on Observability in Closed Systems
18 pages, 4 figures
Phys.Rev. A62 (2000) 042104
10.1103/PhysRevA.62.042104
null
quant-ph gr-qc
null
Measurements are ordinarily described with respect to absolute "Newtonian" time. In reality however, the switching-on of the measuring device at the instance of the measurement requires a timing device. Hence the classical time $t$ must be replaced by a suitable quantum time variable $\tau$ of a physical clock. The main issue raised in this article is that while doing so, we can no longer neglect the {\em back-reaction} due to the measurement on the clock. This back-reaction yields a bound on the accuracy of the measurement. When this bound is violated the result of a measurement is generally not an eigenvalue of the observable, and furthermore, the state of the system after the measurement is generally not a pure state. We argue that as a consequence, a sub-class of observables in a closed system cannot be realized by a measurement.
[ { "version": "v1", "created": "Thu, 2 Sep 1999 13:07:10 GMT" } ]
2009-10-31T00:00:00
[ [ "Casher", "Aharon", "" ], [ "Reznik", "Benni", "" ] ]
quant-ph/9909011
Leah Henderson
L. Henderson and V. Vedral
Information, Relative Entropy of Entanglement and Irreversibility
10 pages, no figures
Physical Review Letters, vol. 84, 10, pp.2263-6, 2000
10.1103/PhysRevLett.84.10
null
quant-ph
null
Previously proposed measures of entanglement, such as entanglement of formation and assistance, are shown to be special cases of the relative entropy of entanglement. The difference between these measures for an ensemble of mixed states is shown to depend on the availability of classical information about particular members of the ensemble. Based on this, relations between relative entropy of entanglement and mutual information are derived.
[ { "version": "v1", "created": "Thu, 2 Sep 1999 16:20:21 GMT" } ]
2009-10-31T00:00:00
[ [ "Henderson", "L.", "" ], [ "Vedral", "V.", "" ] ]
quant-ph/9909012
Tomoyuki Yamakami
Tomoyuki Yamakami
Analysis of Quantum Functions
The complete version of the conference paper appeared in the Proceedings of the 19th International Conference on the Foundations of Software Technology and Theoretical Computer Science, Lecture Notes in Computer Science, Springer-Verlag, Vol.1738, pp.407-419, 1999
International Journal of Foundations of Computer Science, Vol.14(5), pp.815-852, October 2003.
null
null
quant-ph cs.CC
null
This paper initiates a systematic study of quantum functions, which are (partial) functions defined in terms of quantum mechanical computations. Of all quantum functions, we focus on resource-bounded quantum functions whose inputs are classical bit strings. We prove complexity-theoretical properties and unique characteristics of these quantum functions by recent techniques developed for the analysis of quantum computations. We also discuss relativized quantum functions that make adaptive and nonadaptive oracle queries.
[ { "version": "v1", "created": "Thu, 2 Sep 1999 17:23:26 GMT" }, { "version": "v2", "created": "Fri, 17 Sep 1999 21:09:31 GMT" }, { "version": "v3", "created": "Fri, 1 Nov 2002 18:50:05 GMT" }, { "version": "v4", "created": "Thu, 7 Aug 2003 13:12:43 GMT" } ]
2007-05-23T00:00:00
[ [ "Yamakami", "Tomoyuki", "" ] ]
quant-ph/9909013
Holger F. Hofmann
Holger F. Hofmann
Nonclassical correlations of phase noise and photon number in quantum nondemolition measurements
16 pages, 5 figures, final version to be published in Phys. Rev. A, Clarifications of the nature of the measurement result and the noise added in section II
Phys. Rev. A 61, 033815 (2000)
10.1103/PhysRevA.61.033815
null
quant-ph physics.optics
null
The continuous transition from a low resolution quantum nondemolition measurement of light field intensity to a precise measurement of photon number is described using a generalized measurement postulate. In the intermediate regime, quantization appears as a weak modulation of measurement probability. In this regime, the measurement result is strongly correlated with the amount of phase decoherence introduced by the measurement interaction. In particular, the accidental observation of half integer photon numbers preserves phase coherence in the light field, while the accidental observation of quantized values increases decoherence. The quantum mechanical nature of this correlation is discussed and the implications for the general interpretation of quantization are considered.
[ { "version": "v1", "created": "Fri, 3 Sep 1999 07:37:57 GMT" }, { "version": "v2", "created": "Wed, 1 Dec 1999 08:27:31 GMT" } ]
2009-10-31T00:00:00
[ [ "Hofmann", "Holger F.", "" ] ]
quant-ph/9909014
Andreas Klappenecker
Andreas Klappenecker
Wavelets and Wavelet Packets on Quantum Computers
11 pages, 10 postscript figure, to appear in Proc. of Wavelet Applications in Signal and Image Processing VII
null
10.1117/12.366826
null
quant-ph
null
We show how periodized wavelet packet transforms and periodized wavelet transforms can be implemented on a quantum computer. Surprisingly, we find that the implementation of wavelet packet transforms is less costly than the implementation of wavelet transforms on a quantum computer.
[ { "version": "v1", "created": "Fri, 3 Sep 1999 19:32:42 GMT" } ]
2015-06-26T00:00:00
[ [ "Klappenecker", "Andreas", "" ] ]
quant-ph/9909015
P. Narayana Swamy
P. Narayana Swamy
q-deformed fermion oscillators, zero-point energy and inclusion-exclusion principle
10 pages, Latex, submitted to Physical Review E
null
null
null
quant-ph
null
The theory of Fermion oscillators has two essential ingredients: zero-point energy and Pauli exclusion principle. We devlop the theory of the statistical mechanics of generalized q-deformed Fermion oscillator algebra with inclusion principle (i.e., without the exclusion principle), which corresponds to ordinary fermions with Pauli exclusion principle in the classical limit $q \to 1$. Some of the remarkable properties of this theory play a crucial role in the understanding of the q-deformed Fermions. We show that if we insist on the weak exclusion principle, then the theory has the expected low temperature limit as well as the correct classical q-limit.
[ { "version": "v1", "created": "Fri, 3 Sep 1999 19:07:47 GMT" } ]
2007-05-23T00:00:00
[ [ "Swamy", "P. Narayana", "" ] ]
quant-ph/9909016
Hans Halvorson
Rob Clifton (Depts. of Philosophy and History & Philosophy of Science, University of Pittsburgh), Hans Halvorson (Depts. of Mathematics and Philosophy, University of Pittsburgh), Adrian Kent (DAMTP, University of Cambridge)
Non-local Correlations are Generic in Infinite-Dimensional Bipartite Systems
8 pages, RevTeX
Phys. Rev. A 61, 042101 (2000)
10.1103/PhysRevA.61.042101
null
quant-ph
null
It was recently shown that the nonseparable density operators for a bipartite system are trace norm dense if either factor space has infinite dimension. We show here that non-local states -- i.e., states whose correlations cannot be reproduced by any local hidden variable model -- are also dense. Our constructions distinguish between the cases where both factor spaces are infinite-dimensional, where we show that states violating the CHSH inequality are dense, and the case where only one factor space is infinite-dimensional, where we identify open neighborhoods of nonseparable states that do not violate the CHSH inequality but show that states with a subtler form of non-locality (often called "hidden" non-locality) remain dense.
[ { "version": "v1", "created": "Fri, 3 Sep 1999 22:38:13 GMT" }, { "version": "v2", "created": "Fri, 3 Sep 1999 23:02:14 GMT" } ]
2009-10-31T00:00:00
[ [ "Clifton", "Rob", "", "Depts. of Philosophy and History & Philosophy of Science,\n University of Pittsburgh" ], [ "Halvorson", "Hans", "", "Depts. of Mathematics and\n Philosophy, University of Pittsburgh" ], [ "Kent", "Adrian", "", "DAMTP, University of\n Cambridge" ] ]
quant-ph/9909017
Hagen Kleinert
Boris Kastening and Hagen Kleinert
Efficient Algorithm for Perturbative Calculation of Multiloop Feynman Integrals
Author Information under http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of paper also at http://www.physik.fu-berlin.de/~kleinert/299
Phys.Lett. A269 (2000) 50-54
10.1016/S0375-9601(00)00199-7
null
quant-ph
null
We present an efficient algorithm for calculating multiloop Feynman integrals perturbatively.
[ { "version": "v1", "created": "Sat, 4 Sep 1999 06:56:45 GMT" }, { "version": "v2", "created": "Thu, 21 Oct 1999 06:54:49 GMT" } ]
2009-10-31T00:00:00
[ [ "Kastening", "Boris", "" ], [ "Kleinert", "Hagen", "" ] ]
quant-ph/9909018
Dimitris G. Angelakis
D. G. Angelakis, E. Paspalakis and P. L. Knight
Transient properties of modified reservoir-induced transparency
4 pages RevTex, including 3 figures. To appear in Phys. Rev. A
Phys. Rev. A 61, 055802 (2000)
10.1103/PhysRevA.61.055802
null
quant-ph
null
We investigate the transient response of a $\Lambda$-type system with one transition decaying to a modified radiation reservoir with an inverse square-root singular density of modes at threshold, under conditions of transparency. We calculate the time evolution of the linear susceptibility for the probe laser field and show that, depending on the strength of the coupling to the modified vacuum and the background decay, the probe transmission can exhibit behaviour ranging from underdamped to overdamped oscillations. Transient gain without population inversion is also possible depending on the system's parameters.
[ { "version": "v1", "created": "Sat, 4 Sep 1999 18:13:11 GMT" }, { "version": "v2", "created": "Fri, 21 Jan 2000 15:51:24 GMT" } ]
2009-10-31T00:00:00
[ [ "Angelakis", "D. G.", "" ], [ "Paspalakis", "E.", "" ], [ "Knight", "P. L.", "" ] ]
quant-ph/9909019
Martti Havukainen
Martti Havukainen
Comparisons of spectra determined using detector atoms and spatial correlation functions
8 pages, 8 figures
null
10.1080/09500340008232165
HIP-1999-50/TH
quant-ph
null
We show how two level atoms can be used to determine the local time dependent spectrum. The method is applied to a one dimensional cavity. The spectrum obtained is compared with the mode spectrum determined using spatially filtered second order correlation functions. The spectra obtained using two level atoms give identical results with the mode spectrum. One benefit of the method is that only one time averages are needed. It is also more closely related to a realistic measurement scheme than any other definition of a time dependent spectrum.
[ { "version": "v1", "created": "Mon, 6 Sep 1999 08:43:29 GMT" } ]
2015-06-26T00:00:00
[ [ "Havukainen", "Martti", "" ] ]
quant-ph/9909020
Michael Nielsen
M. A. Nielsen
Probability distributions consistent with a mixed state
6 pages, submitted to Physical Review A
Physical Review A 61 (6): Art. No. 064301 (2000)
10.1103/PhysRevA.62.052308
null
quant-ph
null
A density matrix $\rho$ may be represented in many different ways as a mixture of pure states, $\rho = \sum_i p_i |\psi_i\ra \la \psi_i|$. This paper characterizes the class of probability distributions $(p_i)$ that may appear in such a decomposition, for a fixed density matrix $\rho$. Several illustrative applications of this result to quantum mechanics and quantum information theory are given.
[ { "version": "v1", "created": "Mon, 6 Sep 1999 08:38:24 GMT" } ]
2009-10-31T00:00:00
[ [ "Nielsen", "M. A.", "" ] ]
quant-ph/9909021
Andrew Scott Parkins
A.S. Parkins and H.J. Kimble
Proposal for teleportation of the wave function of a massive particle
4 pages, 3 figures
null
null
null
quant-ph
null
We propose a scheme for teleporting an atomic center-of-mass wave function between distant locations. The scheme uses interactions in cavity quantum electrodynamics to facilitate a coupling between the motion of an atom trapped inside a cavity and external propagating light fields. This enables the distribution of quantum entanglement and the realization of the required motional Bell-state analysis.
[ { "version": "v1", "created": "Mon, 6 Sep 1999 23:33:06 GMT" } ]
2007-05-23T00:00:00
[ [ "Parkins", "A. S.", "" ], [ "Kimble", "H. J.", "" ] ]
quant-ph/9909022
Piotr Rozmej
R.Arvieu (ISN, Grenoble, France) and P.Rozmej (University MCS, Lublin, Poland)
Squeezed angular momentum coherent states: construction and time evolution
4 pages, RevTeX,(needs epsfig.sty). Presented on 6th International Conference on Squeezed States and Uncertainty Relations, Napoli, 24-29 May 1999
null
null
null
quant-ph
null
A family of angular momentum coherent states on the sphere is constructed using previous work by Aragone et al [1]. These states depend on a complex parameter which allows an arbitrary squeezing of the angular momentum uncertainties. The time evolution of these states is analyzed assuming a rigid body hamiltonian. The rich scenario of fractional revivals is exhibited with cloning and many interference effects.
[ { "version": "v1", "created": "Tue, 7 Sep 1999 15:47:24 GMT" } ]
2007-05-23T00:00:00
[ [ "Arvieu", "R.", "", "ISN, Grenoble, France" ], [ "Rozmej", "P.", "", "University MCS, Lublin,\n Poland" ] ]
quant-ph/9909023
Piotr Rozmej
M.Turek, P.Rozmej (University MCS, Lublin, Poland) and R. Arvieu (ISN, Grenoble, France)
Spin-orbit pendulum - Relativistic extension
4 pages, LaTeX2e (appolb.cls included). Presented at XXVI Mazurian Lakes School of Physics on Nuclear Physics at the Turn of the Century, Krzyze, Poland, September 1-11, 1999. To appear in Acta Phys. Polon. B (2000)
Acta Phys. Polon. B31 (2000) 517
null
null
quant-ph
null
We discuss an extension of the theory of {\em spin-orbit pendulum} phenomenon given in [1] to relativistic approach. It is done within the so called Dirac Oscillator. Our first results, focusing on circular wave packet motion have been published recently [2]. The scope of this paper is motion of a linear wave packet. In relativistic approach we found {\em Zitterbewegung} in spin-orbit motion (in Dirac representation) due to coupling to negative energy states. This effect is washed out in the Foldy-Wouthuysen representation. Another important change with respect to non-relativistic case is the loss of periodicity. The phenomenon reminds the time evolution of population inversion in Jaynes-Cummings model.
[ { "version": "v1", "created": "Tue, 7 Sep 1999 17:40:29 GMT" } ]
2007-05-23T00:00:00
[ [ "Turek", "M.", "", "University MCS, Lublin, Poland" ], [ "Rozmej", "P.", "", "University MCS, Lublin, Poland" ], [ "Arvieu", "R.", "", "ISN,\n Grenoble, France" ] ]
quant-ph/9909024
Serguei Khlebnikov
S. Khlebnikov
Thermal fluctuations in macroscopic quantum memory
9 pages, revtex, 2 figures; a minor correction for v2; small corrections and some added details for v3
null
null
PURD-TH-99-07
quant-ph cond-mat.supr-con
null
We describe macroscopic quantum memory devices based on type-II toroidal superconductors and estimate in one case and compute in another the rates at which quantum information stored in these devices ``degrades'' because of thermal fluctuations. In the case when the entire solid torus is superconducting, the Boltzmann factor in the rate corresponds to a well-defined critical fluctuation, and the rate is suppressed exponentially with the linear size of the system. In the case when superconductivity is confined to the surface of the torus, the rate is determined by diffusive motion of vortices around the torus and does not depend exponentially on the linear size; we find, however, that when the two dimensions of the torus are comparable the rate does not contain the usual volume enhancement factor, i.e. it does not grow with the total surface area of the sample. We describe a possible way to write to and read from this quantum memory.
[ { "version": "v1", "created": "Tue, 7 Sep 1999 22:51:17 GMT" }, { "version": "v2", "created": "Mon, 27 Sep 1999 20:49:55 GMT" }, { "version": "v3", "created": "Thu, 4 Nov 1999 21:33:35 GMT" } ]
2007-05-23T00:00:00
[ [ "Khlebnikov", "S.", "" ] ]
quant-ph/9909025
Toshihiko Ono
Toshihiko Ono
Structure behind Mechanics I: Foundation
20 pages; trimmed
null
null
null
quant-ph
null
This paper proposes a basic theory on physical reality and a new foundation for quantum mechanics and classical mechanics. It presents a scenario not only to solve the problem of the arbitrariness on the operator ordering for the quantization procedure, but also to clarify how the classical-limit occurs. This paper is the first of the three papers into which the previous paper quant-ph/9906130 has been separated for readability.
[ { "version": "v1", "created": "Wed, 8 Sep 1999 17:49:29 GMT" }, { "version": "v2", "created": "Thu, 9 Sep 1999 03:08:28 GMT" }, { "version": "v3", "created": "Wed, 15 Sep 1999 04:07:36 GMT" } ]
2007-05-23T00:00:00
[ [ "Ono", "Toshihiko", "" ] ]
quant-ph/9909026
Valerie Nowak
Stephen L. Adler and Lawrence P. Horwitz
Structure and Properties of Hughston's Stochastic Extension of the Schr\"odinger Equation
Plain Tex, no figures
null
10.1063/1.533255
IASSNS-HEP-99-83
quant-ph
null
Hughston has recently proposed a stochastic extension of the Schr\"odinger equation, expressed as a stochastic differential equation on projective Hilbert space. We derive new projective Hilbert space identities, which we use to give a general proof that Hughston's equation leads to state vector collapse to energy eigenstates, with collapse probabilities given by the quantum mechanical probabilities computed from the initial state. We discuss the relation of Hughston's equation to earlier work on norm-preserving stochastic equations, and show that Hughston's equation can be written as a manifestly unitary stochastic evolution equation for the pure state density matrix. We discuss the behavior of systems constructed as direct products of independent subsystems, and briefly address the question of whether an energy-based approach, such as Hughston's, suffices to give an objective interpretation of the measurement process in quantum mechanics.
[ { "version": "v1", "created": "Wed, 8 Sep 1999 21:12:59 GMT" } ]
2015-06-26T00:00:00
[ [ "Adler", "Stephen L.", "" ], [ "Horwitz", "Lawrence P.", "" ] ]
quant-ph/9909027
Gennady Berman
G.P.Berman, G.D. Doolen, G.V. Lopez, and V.I. Tsifrinovich
Non-Resonant Effects in Implementation of Quantum Shor Algorithm
11 pages, 13 figures
null
10.1103/PhysRevA.61.042307
null
quant-ph
null
We simulate Shor's algorithm on an Ising spin quantum computer. The influence of non-resonant effects is analyzed in detail. It is shown that our ``$2\pi k$''-method successfully suppresses non-resonant effects even for relatively large values of the Rabi frequency.
[ { "version": "v1", "created": "Wed, 8 Sep 1999 21:24:18 GMT" }, { "version": "v2", "created": "Thu, 9 Sep 1999 00:14:39 GMT" } ]
2009-10-31T00:00:00
[ [ "Berman", "G. P.", "" ], [ "Doolen", "G. D.", "" ], [ "Lopez", "G. V.", "" ], [ "Tsifrinovich", "V. I.", "" ] ]
quant-ph/9909028
Viatcheslav V. Dobrovitski
M. I. Katsnelson, V. V. Dobrovitski, and B. N. Harmon
Propagation of local decohering action in distributed quantum systems
6 REVTeX pages, no figures. Introduction and discussion sections are extended
Phys. Rev. A 62, 022118 (July 2000)
10.1103/PhysRevA.62.022118
null
quant-ph
null
We study propagation of the decohering influence caused by a local measurement performed on a distributed quantum system. As an example, the gas of bosons forming a Bose-Einstein condensate is considered. We demonstrate that the local decohering perturbation exerted on the measured region propagates over the system in the form of a decoherence wave, whose dynamics is governed by elementary excitations of the system. We argue that the post-measurement evolution of the system (determined by elementary excitations) is of importance for transfer of decoherence, while the initial collapse of the wave function has negligible impact on the regions which are not directly affected by the measurement.
[ { "version": "v1", "created": "Thu, 9 Sep 1999 06:04:58 GMT" }, { "version": "v2", "created": "Thu, 16 Sep 1999 17:08:24 GMT" }, { "version": "v3", "created": "Sun, 24 Sep 2000 08:06:02 GMT" } ]
2009-10-31T00:00:00
[ [ "Katsnelson", "M. I.", "" ], [ "Dobrovitski", "V. V.", "" ], [ "Harmon", "B. N.", "" ] ]
quant-ph/9909029
Massimiliano F. Sacchi
G. M. D'Ariano, M. F. Sacchi, R. Seno
Feedback-assisted measurement of the free mass position under the Standard Quantum Limit
18 pages, LaTeX with cimento.cls documentclass (included)
Nuovo Cimento B, {\bf 114}, 775 (1999)
null
null
quant-ph
null
The Standard Quantum Limit (SQL) for the measurement of a free mass position is illustrated, along with two necessary conditions for breaching it. A measurement scheme that overcomes the SQL is engineered. It can be achieved in three-steps: i) a pre-squeezing stage; ii) a standard von Neumann measurement with momentum-position object-probe interaction and iii) a feedback. Advantages and limitations of this scheme are discussed. It is shown that all of the three steps are needed in order to overcome the SQL. In particular, the von Neumann interaction is crucial in getting the right state reduction, whereas other experimentally achievable Hamiltonians, as, for example, the radiation-pressure interaction, lead to state reductions that on the average cannot overcome the SQL.
[ { "version": "v1", "created": "Thu, 9 Sep 1999 10:14:27 GMT" } ]
2007-05-23T00:00:00
[ [ "D'Ariano", "G. M.", "" ], [ "Sacchi", "M. F.", "" ], [ "Seno", "R.", "" ] ]
quant-ph/9909030
Margaret Reid
M. D. Reid
Quantum cryptography with a predetermined key, using continuous variable Einstein-Podolsky-Rosen correlations
11 pages,3 figures, changes are important,presented at QELS(May,2000) San Francisco
Phys. Rev. A62,062308(2000)
10.1103/PhysRevA.62.062308
null
quant-ph
null
Correlations of the type discussed by EPR in their original 1935 paradox for continuous variables exist for the quadrature phase amplitudes of two spatially separated fields. These correlations were experimentally reported in 1992. We propose to use such EPR beams in quantum cryptography, to transmit with high efficiency messages in such a way that the receiver and sender may later determine whether eavesdropping has occurred. The merit of the new proposal is in the possibility of transmitting a reasonably secure yet predetermined key. This would allow relay of a cryptographic key over long distances in the presence of lossy channels.
[ { "version": "v1", "created": "Thu, 9 Sep 1999 12:17:55 GMT" }, { "version": "v2", "created": "Fri, 12 Jan 2001 08:27:22 GMT" } ]
2009-10-31T00:00:00
[ [ "Reid", "M. D.", "" ] ]
quant-ph/9909031
Mio Murao
Mio Murao, Martin B. Plenio and Vlatko Vedral
Quantum information distribution via entanglement
15 pages, 3 figures
Phys. Rev. A 60, 032311 (2000)
10.1103/PhysRevA.61.032311
null
quant-ph
null
We present a generalization of quantum teleportation that distributes quantum information from a sender's $d$-level particle to $N_o$ particles held by remote receivers via an initially shared multiparticle entangled state. This entangled state functions as a multiparty quantum information distribution channel between the sender and the receivers. The structure of the distribution channel determines how quantum information is processed. Our generalized teleportation scheme allows multiple receivers at arbitrary locations, and can be used for applications such as optimal quantum information broadcasting, asymmetric telecloning, and quantum error correction.
[ { "version": "v1", "created": "Thu, 9 Sep 1999 15:09:09 GMT" } ]
2009-10-31T00:00:00
[ [ "Murao", "Mio", "" ], [ "Plenio", "Martin B.", "" ], [ "Vedral", "Vlatko", "" ] ]
quant-ph/9909032
Dmitry Kamenev
G.P. Berman, G.D. Doolen, G.V.Lopez, and V.I. Tsifrinovich
Simulations of Quantum Logic Operations in Quantum Computer with Large Number of Qubits
13 pages, 15 figures
null
10.1103/PhysRevA.61.062305
null
quant-ph
null
We report the first simulations of the dynamics of quantum logic operations with a large number of qubits (up to 1000). A nuclear spin chain in which selective excitations of spins is provided by the gradient of the external magnetic field is considered. The spins interact with their nearest neighbors. We simulate the quantum control-not (CN) gate implementation for remote qubits which provides the long-distance entanglement. Our approach can be applied to any implementation of quantum logic gates involving a large number of qubits.
[ { "version": "v1", "created": "Thu, 9 Sep 1999 18:06:20 GMT" } ]
2009-10-31T00:00:00
[ [ "Berman", "G. P.", "" ], [ "Doolen", "G. D.", "" ], [ "Lopez", "G. V.", "" ], [ "Tsifrinovich", "V. I.", "" ] ]
quant-ph/9909033
Dmitry Kamenev
G.P. Berman, G.D. Doolen, P.C. Hammel, and V.I. Tsifrinovich
Solid-State Nuclear Spin Quantum Computer Based on Magnetic Resonance Force Microscopy
16 pages, 5 figures
null
10.1103/PhysRevB.61.14694
null
quant-ph
null
We propose a nuclear spin quantum computer based on magnetic resonance force microscopy (MRFM). It is shown that an MRFM single-electron spin measurement provides three essential requirements for quantum computation in solids: (a) preparation of the ground state, (b) one- and two- qubit quantum logic gates, and (c) a measurement of the final state. The proposed quantum computer can operate at temperatures up to 1K.
[ { "version": "v1", "created": "Thu, 9 Sep 1999 20:42:08 GMT" } ]
2009-10-31T00:00:00
[ [ "Berman", "G. P.", "" ], [ "Doolen", "G. D.", "" ], [ "Hammel", "P. C.", "" ], [ "Tsifrinovich", "V. I.", "" ] ]
quant-ph/9909034
Zhaog
Gang Zhao
Explanation of Quantum Mechanics
LaTex,2 pages
null
null
null
quant-ph
null
By assuming that the kinetic energy,potential energy,momentum,and some other physical quantities of a particle exist in the field out of the particle,the Schrodinger equation is an equation describing field of a particle,but not the particle itself.
[ { "version": "v1", "created": "Fri, 10 Sep 1999 00:52:59 GMT" } ]
2007-05-23T00:00:00
[ [ "Zhao", "Gang", "" ] ]