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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/0701034 | Oliver Muelken | Oliver Muelken, Veronika Bierbaum, Alexander Blumen | Localization of coherent exciton transport in phase space | 8 pages, 9 figures. slight revision of the text and addition of a new
figure. to be published in Phys. Rev. E | Phys. Rev. E 75, 031121 (2007) | null | null | quant-ph cond-mat.stat-mech | null | We study numerically the dynamics of excitons on discrete rings in the
presence of static disorder. Based on continuous-time quantum walks we compute
the time evolution of the Wigner function (WF) both for pure diagonal (site)
disorder, as well as for diagonal and off-diagonal (site and transfer)
disorder. In both cases, large disorder leads to localization and destroys the
characteristic phase space patterns of the WF found in the absence of disorder.
| [
{
"version": "v1",
"created": "Mon, 8 Jan 2007 07:40:13 GMT"
},
{
"version": "v2",
"created": "Fri, 16 Feb 2007 08:22:11 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Muelken",
"Oliver",
""
],
[
"Bierbaum",
"Veronika",
""
],
[
"Blumen",
"Alexander",
""
]
]
|
quant-ph/0701035 | XiaoDi Wu | XiaoDi Wu | Comments on quant-ph/0609176 | null | null | null | null | quant-ph | null | In this note, we show the mistake which has been made in quant-ph/0609176.
Further more, we provide a sketch of proof to show the impossibility of the
effort of such kind toward improving the efficiency of Grover's Algorithm.
| [
{
"version": "v1",
"created": "Mon, 8 Jan 2007 15:12:40 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Wu",
"XiaoDi",
""
]
]
|
quant-ph/0701036 | Kurt Jacobs | Kurt Jacobs, Austin P. Lund | Feedback Control of Non-linear Quantum Systems: a Rule of Thumb | 4 pages, revtex4, 1 eps figure | Phys. Rev. Lett. 99, 020501 (2007) | 10.1103/PhysRevLett.99.020501 | null | quant-ph | null | We show that in the regime in which feedback control is most effective --
when measurements are relatively efficient, and feedback is relatively strong
-- then, in the absence of any sharp inhomogeneity in the noise, it is always
best to measure in a basis that does not commute with the system density matrix
than one that does. That is, it is optimal to make measurements that disturb
the state one is attempting to stabilize.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 03:50:10 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Jacobs",
"Kurt",
""
],
[
"Lund",
"Austin P.",
""
]
]
|
quant-ph/0701037 | Andreas Klappenecker | Salah A. Aly, Andreas Klappenecker, Pradeep Kiran Sarvepalli | Quantum Convolutional Codes Derived From Reed-Solomon and Reed-Muller
Codes | 5 pages; updated parameters of classical (whence quantum) RM
convolutional codes | null | null | null | quant-ph cs.IT math.IT | null | Convolutional stabilizer codes promise to make quantum communication more
reliable with attractive online encoding and decoding algorithms. This paper
introduces a new approach to convolutional stabilizer codes based on direct
limit constructions. Two families of quantum convolutional codes are derived
from generalized Reed-Solomon codes and from Reed- Muller codes. A Singleton
bound for pure convolutional stabilizer codes is given.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 04:29:03 GMT"
},
{
"version": "v2",
"created": "Mon, 22 Jan 2007 17:14:47 GMT"
}
]
| 2007-07-13T00:00:00 | [
[
"Aly",
"Salah A.",
""
],
[
"Klappenecker",
"Andreas",
""
],
[
"Sarvepalli",
"Pradeep Kiran",
""
]
]
|
quant-ph/0701038 | S. V. Prants | V.Yu. Argonov and S.V. Prants | Theory of chaotic atomic transport in an optical lattice | 14 pages, 8 figures | V.Yu. Argonov and S.V. Prants. Theory of chaotic atomic transport
in an optical lattice. Phys. Rev. A. V.75 (2007) art. no. 063428. | 10.1103/PhysRevA.75.063428 | null | quant-ph | null | A semiclassical theory of chaotic atomic transport in a one-dimensional
nondissipative optical lattice is developed. Using the basic equations of
motion for the Bloch and translational atomic variables, we derive a stochastic
map for the synchronized component of the atomic dipole moment that determines
the center-of-mass motion. We find the analytical relations between the atomic
and lattice parameters under which atoms typically alternate between flying
through the lattice and being trapped in the wells of the optical potential. We
use the stochastic map to derive formulas for the probability density functions
(PDFs) for the flight and trapping events. Statistical properties of chaotic
atomic transport strongly depend on the relations between the atomic and
lattice parameters. We show that there is a good quantitative agreement between
the analytical PDFs and those computed with the stochastic map and the basic
equations of motion for different ranges of the parameters. Typical flight and
trapping PDFs are shown to be broad distributions with power law ``heads'' with
the slope -1.5 and exponential ``tails''. The lengths of the power law and
exponential parts of the PDFs depend on the values of the parameters and can be
varied continuously. We find analytical conditions, under which deterministic
atomic transport has fractal properties, and explain a hierarchical structure
of the dynamical fractals.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 06:06:23 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Argonov",
"V. Yu.",
""
],
[
"Prants",
"S. V.",
""
]
]
|
quant-ph/0701039 | Shahriar S. Afshar | Shahriar S. Afshar | Violation of Bohr's Complementarity: One Slit or Both? | 6 pages, 4 figures, Vaxjo University Conference, QUANTUM THEORY:
Reconsideration of Foundations - 3, January 4, 2006 | AIP Cof. Proc. 810, (2006) 294-299 | 10.1063/1.2158731 | null | quant-ph | null | We have implemented a novel double-slit "which-way" experiment which raises
interesting questions of interpretation. Coherent laser light is passed through
a converging lens and then through a dual pinhole producing two beams crossing
over at the focal point of the lens, and fully separating further downstream
providing which-way information. A thin wire is then placed at a minimum of the
interference pattern formed at the cross-over region. No significant reduction
in the total flux or resolution of the separated beams is found, providing
evidence for coexistence of perfect interference and which-way information in
the same experiment, contrary to the common readings of Bohr's principle of
complementarity. This result further supports the conclusions of the original
experiment by the author in which an imaging lens was employed to obtain
which-way information. Finally, a short discussion of the novel
non-perturbative measurement technique for ensemble properties is offered.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 06:21:29 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Afshar",
"Shahriar S.",
""
]
]
|
quant-ph/0701040 | Pramod Joag | Ali Saif M. Hassan and Pramod Joag | On the degree conjecture for separability of multipartite quantum states | 17 pages, 3 figures. Comments are welcome | JOURNAL OF MATHEMATICAL PHYSICS 49, 012105 (2008) | 10.1063/1.2830978 | null | quant-ph | null | We settle the so-called degree conjecture for the separability of
multipartite quantum states, which are normalized graph Laplacians, first given
by Braunstein {\it et al.} [Phys. Rev. A \textbf{73}, 012320 (2006)]. The
conjecture states that a multipartite quantum state is separable if and only if
the degree matrix of the graph associated with the state is equal to the degree
matrix of the partial transpose of this graph. We call this statement to be the
strong form of the conjecture. In its weak version, the conjecture requires
only the necessity, that is, if the state is separable, the corresponding
degree matrices match. We prove the strong form of the conjecture for {\it
pure} multipartite quantum states, using the modified tensor product of graphs
defined in [J. Phys. A: Math. Theor. \textbf{40}, 10251 (2007)], as both
necessary and sufficient condition for separability. Based on this proof, we
give a polynomial-time algorithm for completely factorizing any pure
multipartite quantum state. By polynomial-time algorithm we mean that the
execution time of this algorithm increases as a polynomial in $m,$ where $m$ is
the number of parts of the quantum system. We give a counter-example to show
that the conjecture fails, in general, even in its weak form, for multipartite
mixed states. Finally, we prove this conjecture, in its weak form, for a class
of multipartite mixed states, giving only a necessary condition for
separability.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 09:48:35 GMT"
},
{
"version": "v2",
"created": "Sat, 2 Feb 2008 06:28:52 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Hassan",
"Ali Saif M.",
""
],
[
"Joag",
"Pramod",
""
]
]
|
quant-ph/0701041 | Dusanka Perisic | Z.Lozanov--Crvenkovic, D.Perisic | Hermite Expansions of Elements of Generalized Gelfand-Shilov space | 19 pages | null | null | null | quant-ph math.FA | null | We characterize the elements of generalized Gelfand Shilov spaces in terms of
the coefficients of their Fourier-Hermite expansion. The technique we use can
be applied both in quasianalytic and nonquasianalytic case. The
characterizations imply the kernel theorems for the dual spaces. The cases when
the test space is quasianalytic are important in quantum field theory with a
fundamental length, see for example papers of E.Bruning and S.Nagamachi,where
it was conjectured that the properties of the space of Fourier hyper functions,
which is isomorphic with S^1_1 are well adapted for the use in the theory.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 11:27:35 GMT"
},
{
"version": "v2",
"created": "Tue, 30 Jan 2007 13:11:57 GMT"
}
]
| 2007-06-18T00:00:00 | [
[
"Lozanov--Crvenkovic",
"Z.",
""
],
[
"Perisic",
"D.",
""
]
]
|
quant-ph/0701042 | Ramin Golestanian | Ramin Golestanian | Lifshitz Interaction between Dielectric Bodies of Arbitrary Geometry | null | Phys. Rev. Lett. 95, 230601 (2005) | 10.1103/PhysRevLett.95.230601 | null | quant-ph cond-mat.mtrl-sci physics.atom-ph | null | A formulation is developed for the calculation of the
electromagnetic--fluctuation forces for dielectric objects of arbitrary
geometry at small separations, as a perturbative expansion in the dielectric
contrast. The resulting Lifshitz energy automatically takes on the form of a
series expansion of the different many-body contributions. The formulation has
the advantage that the divergent contributions can be readily determined and
subtracted off, and thus makes a convenient scheme for realistic numerical
calculations, which could be useful in designing nano-scale mechanical devices.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 11:57:24 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Golestanian",
"Ramin",
""
]
]
|
quant-ph/0701043 | Rodney Van Meter | Rodney Van Meter, Kae Nemoto, W. J. Munro | Communication Links for Distributed Quantum Computation | 9 pages, 5 figures | IEEE Transactions on Computers, 56(12), 1643--1653, Dec. 2007 | 10.1109/TC.2007.70775 | null | quant-ph | null | Distributed quantum computation requires quantum operations that act over a
distance on error-correction encoded states of logical qubits, such as the
transfer of qubits via teleportation. We evaluate the performance of several
quantum error correction codes, and find that teleportation failure rates of
one percent or more are tolerable when two levels of the [[23,1,7]] code are
used. We present an analysis of performing quantum error correction (QEC) on
QEC-encoded states that span two quantum computers, including the creation of
distributed logical zeroes. The transfer of the individual qubits of a logical
state may be multiplexed in time or space, moving serially across a single
link, or in parallel across multiple links. We show that the performance and
reliability penalty for using serial links is small for a broad range of
physical parameters, making serial links preferable for a large, distributed
quantum multicomputer when engineering difficulties are considered. Such a
multicomputer will be able to factor a 1,024-bit number using Shor's algorithm
with a high probability of success.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 12:24:06 GMT"
}
]
| 2007-10-11T00:00:00 | [
[
"Van Meter",
"Rodney",
""
],
[
"Nemoto",
"Kae",
""
],
[
"Munro",
"W. J.",
""
]
]
|
quant-ph/0701044 | Simone Montangero | Franco Pellegrini, Simone Montangero | Fractal Fidelity as a signature of Quantum Chaos | 5 pages, 5 figures | Phys. Rev. A 76, 052327 (2007) | 10.1103/PhysRevA.76.052327 | null | quant-ph | null | We analyze the fidelity of a quantum simulation and we show that it displays
fractal fluctuations iff the simulated dynamics is chaotic. This analysis
allows us to investigate a given simulated dynamics without any prior
knowledge. In the case of integrable dynamics, the appearance of fidelity
fractal fluctuations is a signal of a highly corrupted simulation. We
conjecture that fidelity fractal fluctuations are a signature of the appearance
of quantum chaos. Our analysis can be realized already by a few qubit quantum
processor.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 13:09:09 GMT"
},
{
"version": "v2",
"created": "Wed, 3 Oct 2007 15:55:54 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Pellegrini",
"Franco",
""
],
[
"Montangero",
"Simone",
""
]
]
|
quant-ph/0701045 | Zhang Zhanjun Dr. | Zhan-jun Zhang, Yi-min Liu, Hao Yuan | Withdrawing this manuscript | 5 pages | null | null | null | quant-ph | null | Recently Z. S. Zhang et al [Phys. Lett. A 356(2006)199] have proposed an
one-way quantum identity authentication scheme and claimed that it can verify
the user's identity and update securely the initial authentication key for
reuse.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 13:30:24 GMT"
},
{
"version": "v2",
"created": "Wed, 10 Jan 2007 07:46:49 GMT"
},
{
"version": "v3",
"created": "Fri, 12 Jan 2007 15:18:11 GMT"
},
{
"version": "v4",
"created": "Mon, 22 Jan 2007 11:22:16 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Zhang",
"Zhan-jun",
""
],
[
"Liu",
"Yi-min",
""
],
[
"Yuan",
"Hao",
""
]
]
|
quant-ph/0701046 | Ting Gao | Mei-Yu Wang, Feng-Li Yan | Three-party simultaneous quantum secure direct communication scheme with
EPR pairs | 3 pages | Chinese Physics Letters, 24 (2007) 2486. | 10.1088/0256-307X/24/9/007 | null | quant-ph | null | We present a scheme for three-party simultaneous quantum secure direct
communication by using EPR pairs. In the scheme, three legitimate parties can
simultaneously exchange their secret messages. It is also proved to be secure
against the intercept-and-resend attack, the disturbance attack and the
entangled-and-measure attack.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 14:02:11 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Wang",
"Mei-Yu",
""
],
[
"Yan",
"Feng-Li",
""
]
]
|
quant-ph/0701047 | Slavnov A. Dmitry | D.A. Slavnov | The Possibility of Reconciling Quantum Mechanics with Classical
Probability Theory | Latex, 14 pages, 1 figure | Theor.Math.Phys.149:1690-1701,2006; Teor.Mat.Fiz.149:457-472,2006 | 10.1007/s11232-006-0151-0 | null | quant-ph hep-th | null | We describe a scheme for constructing quantum mechanics in which a quantum
system is considered as a collection of open classical subsystems. This allows
using the formal classical logic and classical probability theory in quantum
mechanics. Our approach nevertheless allows completely reproducing the standard
mathematical formalism of quantum mechanics and identifying its applicability
limits. We especially attend to the quantum state reduction problem.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 14:02:21 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Slavnov",
"D. A.",
""
]
]
|
quant-ph/0701048 | Igor Jex | J. Novotny, G. Alber, I. Jex | Network implementation of covariant two-qubit quantum operations | null | null | null | null | quant-ph | null | A six-qubit quantum network consisting of conditional unitary gates is
presented which is capable of implementing a large class of covariant two-qubit
quantum operations. Optimal covariant NOT operations for one and two-qubit
systems are special cases contained in this class. The design of this quantum
network exploits basic algebraic properties which also shed new light onto
these covariant quantum processes.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 14:28:24 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Novotny",
"J.",
""
],
[
"Alber",
"G.",
""
],
[
"Jex",
"I.",
""
]
]
|
quant-ph/0701049 | Bernd Kaltenhaeuser | Bernd Kaltenh\"auser, Harald K\"ubler, Andreas Chromik, J\"urgen
Stuhler, Tilman Pfau, Atac Imamoglu | Electromagnetically Induced Transparency in optically trapped rubidium
atoms | 5 pages, 8 figures | null | null | null | quant-ph | null | We demonstrate electromagnetically induced transparency (EIT) in a sample of
rubidium atoms, trapped in an optical dipole trap. Mixing a small amount of
$\sigma^-$-polarized light to the weak $\sigma^+$-polarized probe pulses, we
are able to measure the absorptive and dispersive properties of the atomic
medium at the same time. Features as small as 4 kHz have been detected on an
absorption line with 20 MHz line width.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 18:39:31 GMT"
},
{
"version": "v2",
"created": "Wed, 10 Jan 2007 15:58:54 GMT"
}
]
| 2016-08-14T00:00:00 | [
[
"Kaltenhäuser",
"Bernd",
""
],
[
"Kübler",
"Harald",
""
],
[
"Chromik",
"Andreas",
""
],
[
"Stuhler",
"Jürgen",
""
],
[
"Pfau",
"Tilman",
""
],
[
"Imamoglu",
"Atac",
""
]
]
|
quant-ph/0701050 | Fabio Dell'Anno | F. Dell'Anno, S. De Siena, and F. Illuminati | Multiphoton Quantum Optics and Quantum State Engineering | 198 pages, 36 eps figures | Phys. Rep. 428, 53 (2006) | 10.1016/j.physrep.2006.01.004 | null | quant-ph | null | We present a review of theoretical and experimental aspects of multiphoton
quantum optics. Multiphoton processes occur and are important for many aspects
of matter-radiation interactions that include the efficient ionization of atoms
and molecules, and, more generally, atomic transition mechanisms;
system-environment couplings and dissipative quantum dynamics; laser physics,
optical parametric processes, and interferometry. A single review cannot
account for all aspects of such an enormously vast subject. Here we choose to
concentrate our attention on parametric processes in nonlinear media, with
special emphasis on the engineering of nonclassical states of photons and
atoms. We present a detailed analysis of the methods and techniques for the
production of genuinely quantum multiphoton processes in nonlinear media, and
the corresponding models of multiphoton effective interactions. We review
existing proposals for the classification, engineering, and manipulation of
nonclassical states, including Fock states, macroscopic superposition states,
and multiphoton generalized coherent states. We introduce and discuss the
structure of canonical multiphoton quantum optics and the associated one- and
two-mode canonical multiphoton squeezed states. This framework provides a
consistent multiphoton generalization of two-photon quantum optics and a
consistent Hamiltonian description of multiphoton processes associated to
higher-order nonlinearities. Finally, we discuss very recent advances that by
combining linear and nonlinear optical devices allow to realize multiphoton
entangled states of the electromnagnetic field, that are relevant for
applications to efficient quantum computation, quantum teleportation, and
related problems in quantum communication and information.
| [
{
"version": "v1",
"created": "Tue, 9 Jan 2007 21:46:02 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Dell'Anno",
"F.",
""
],
[
"De Siena",
"S.",
""
],
[
"Illuminati",
"F.",
""
]
]
|
quant-ph/0701051 | Alessio Serafini | A. Serafini, O.C.O. Dahlsten, D. Gross, and M.B. Plenio | Canonical and micro-canonical typical entanglement of continuous
variable systems | 24 pages, 5 figures, IOP style; conclusions extended, minor layout
adjustment | J. Phys. A: Math. Theor. 40, 9551 (2007) | 10.1088/1751-8113/40/31/027 | null | quant-ph | null | We present a framework, compliant with the general canonical principle of
statistical mechanics, to define measures on the set of pure Gaussian states of
continuous variable systems. Within such a framework, we define two specific
measures, referred to as `micro-canonical' and `canonical', and apply them to
study systematically the statistical properties of the bipartite entanglement
of n-mode pure Gaussian states (as quantified by the entropy of a subsystem).
We rigorously prove the "concentration of measure" around a finite average,
occurring for the entanglement in the thermodynamical limit in both the
canonical and the micro-canonical approach. For finite n, we determine
analytically the average and standard deviation of the entanglement (as
quantified by the reduced purity) between one mode and all the other modes.
Furthermore, we numerically investigate more general situations, clearly
showing that the onset of the concentration of measure already occurs at
relatively small n.
| [
{
"version": "v1",
"created": "Wed, 10 Jan 2007 19:51:21 GMT"
},
{
"version": "v2",
"created": "Wed, 10 Jan 2007 23:01:44 GMT"
}
]
| 2007-08-21T00:00:00 | [
[
"Serafini",
"A.",
""
],
[
"Dahlsten",
"O. C. O.",
""
],
[
"Gross",
"D.",
""
],
[
"Plenio",
"M. B.",
""
]
]
|
quant-ph/0701052 | D. Bar | D. Bar | Decoherence and the appearance of classicality in physical phenomena | 82 pages, 12 PS Figures, Thesis. There are some technical changes
between this submission and the one submitted to the University due to some
limitations imposed upon submissions's size. These changes, wherever occured,
are noted by footnotes | null | null | null | quant-ph | null | It is accepted that among the ways through which a quantum phenomenon
decoheres and becomes a classical one is what is termed in the literature the
Zeno effect. This effect, named after the ancient Greek philosopher Zeno of
Elea (born about 485 B.C), were used in 1977 to analytically predict that an
initial quantum state may be preserved in time by merely repeating a large
number of times, in a finite total time, the experiment of checking its state.
Since then this effect has been experimentally validated and has become an
established physical fact. It has been argued by Simonius that the Zeno effect
must be related not only to quantum phenomena but also to many macroscopic and
classical effects. Thus, since it operates in both quantum and classical
regimes it must cause to a more generalized kind of decoherence than the
restricted one that ``classicalizes'' a quantum phenomenon. We show that this
generalized decoherence, {\it obtained as a result of dense measurement}, not
only gives rise to new phenomena that are demonstrated through new responses of
the densely interacted-upon system but also may physically {\it establish}
them. For that matter we have found and established the analogous {\it space
Zeno effect} which leads to the necessity of an ensemble of related observers
(systems) for the remarked physical validation of new phenomena. As will be
shown in Chapters 3-5 of this work the new phenomena (new responses of the
system) that result from the space Zeno effect may be of an unexpected nature.
We use quantum field theory in addition to the more conventional methods of
analysis and also corroborate our analytical findings by numerical simulations.
| [
{
"version": "v1",
"created": "Wed, 10 Jan 2007 00:26:28 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Bar",
"D.",
""
]
]
|
quant-ph/0701053 | Toby S. Cubitt | T. S. Cubitt, J.I. Cirac | Engineering correlation and entanglement dynamics in spin systems | 4 pages, 4 figures, REVTeX4 format | null | 10.1103/PhysRevLett.100.180406 | null | quant-ph cond-mat.other | null | We show that the correlation and entanglement dynamics of spin systems can be
understood in terms of propagation of spin waves. This gives a simple, physical
explanation of the behaviour seen in a number of recent works, in which a
localised, low-energy excitation is created and allowed to evolve. But it also
extends to the scenario of translationally invariant systems in states far from
equilibrium, which require less local control to prepare. Spin-wave evolution
is completely determined by the system's dispersion relation, and the latter
typically depends on a small number of external, physical parameters.
Therefore, this new insight into correlation dynamics opens up the possibility
not only of predicting but also of controlling the propagation velocity and
dispersion rate, by manipulating these parameters. We demonstrate this
analytically in a simple, example system.
| [
{
"version": "v1",
"created": "Wed, 10 Jan 2007 01:45:36 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Cubitt",
"T. S.",
""
],
[
"Cirac",
"J. I.",
""
]
]
|
quant-ph/0701054 | Lorenzo Salcedo L. | L.L. Salcedo | Comment on ``A quantum-classical bracket that satisfies the Jacobi
identity'' [J. Chem. Phys. 124, 201104 (2006)] | 2 pages, no figures | J. Chem. Phys. 126 (2007) 057101 | 10.1063/1.2431650 | null | quant-ph gr-qc | null | It shown that the quantum-classical dynamical bracket recently proposed in J.
Chem. Phys. 124, 201104 (2006) fails to satisfy the Jacobi identity.
| [
{
"version": "v1",
"created": "Wed, 10 Jan 2007 09:36:03 GMT"
}
]
| 2012-02-09T00:00:00 | [
[
"Salcedo",
"L. L.",
""
]
]
|
quant-ph/0701055 | Jesni Shamsul Shaari Mr | J. S. Shaari, M. R. B. Wahiddin, S. Mancini | Blind encoding into qudits | To appear in Physics Letters A | Physics Letters A, Volume 372, Issue 12, 17 March 2008, Pages
1963-1967 | 10.1016/j.physleta.2007.08.076 | null | quant-ph | null | We consider the problem of encoding classical information into unknown qudit
states belonging to any basis, of a maximal set of mutually unbiased bases, by
one party and then decoding by another party who has perfect knowledge of the
basis. Working with qudits of prime dimensions, we point out a no-go theorem
that forbids shift operations on arbitrary unknown states. We then provide the
necessary conditions for reliable encoding/decoding.
| [
{
"version": "v1",
"created": "Wed, 10 Jan 2007 12:10:03 GMT"
},
{
"version": "v2",
"created": "Mon, 3 Sep 2007 00:45:50 GMT"
}
]
| 2008-07-04T00:00:00 | [
[
"Shaari",
"J. S.",
""
],
[
"Wahiddin",
"M. R. B.",
""
],
[
"Mancini",
"S.",
""
]
]
|
quant-ph/0701056 | Jae-Seung Lee | Jae-Seung Lee, Travis Adams, and A. K. Khitrin | Experimental demonstration of stimulated polarization wave in a chain of
nuclear spins | 8 pages including 3 figures | New J. Phys. 9, 83 (2007) | 10.1088/1367-2630/9/4/083 | null | quant-ph | null | A stimulated wave of polarization, which implements a simple mechanism of
quantum amplification, is experimentally demonstrated in a chain of four
J-coupled nuclear spins, irradiated by a weak radio-frequency transverse field.
The "quantum domino" dynamics, a wave of flipped spins triggered by a flip of
the first spin, has been observed in fully $^{13}$C-labeled sodium butyrate.
| [
{
"version": "v1",
"created": "Wed, 10 Jan 2007 20:53:20 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Lee",
"Jae-Seung",
""
],
[
"Adams",
"Travis",
""
],
[
"Khitrin",
"A. K.",
""
]
]
|
quant-ph/0701057 | Peter van Loock | P. van Loock, W. J. Munro, Kae Nemoto, T. P. Spiller, T. D. Ladd,
Samuel L. Braunstein, and G. J. Milburn | Hybrid Quantum Computation in Quantum Optics | 5 pages, 2 figures | Phys. Rev. A 78, 022303 (2008) | 10.1103/PhysRevA.78.022303 | null | quant-ph | null | We propose a hybrid quantum computing scheme where qubit degrees of freedom
for computation are combined with quantum continuous variables for
communication. In particular, universal two-qubit gates can be implemented
deterministically through qubit-qubit communication, mediated by a
continuous-variable bus mode ("qubus"), without direct interaction between the
qubits and without any measurement of the qubus. The key ingredients are
controlled rotations of the qubus and unconditional qubus displacements. The
controlled rotations are realizable through typical atom-light interactions in
quantum optics. For such interactions, our scheme is universal and works in any
regime, including the limits of weak and strong nonlinearities.
| [
{
"version": "v1",
"created": "Thu, 11 Jan 2007 06:39:02 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"van Loock",
"P.",
""
],
[
"Munro",
"W. J.",
""
],
[
"Nemoto",
"Kae",
""
],
[
"Spiller",
"T. P.",
""
],
[
"Ladd",
"T. D.",
""
],
[
"Braunstein",
"Samuel L.",
""
],
[
"Milburn",
"G. J.",
""
]
]
|
quant-ph/0701058 | Todd Brun | Irving S. Reed and Todd A. Brun (University of Southern California) | A Matrix Factorization of Extended Hamiltonian Leads to $N$-Particle
Pauli Equation | 32 pages, no figures | null | null | null | quant-ph | null | In this paper the Levy-Leblond procedure for linearizing the Schr\"odinger
equation to obtain the Pauli equation for one particle is generalized to obtain
an $N$-particle equation with spin. This is achieved by using the more
universal matrix factorization, $G\tilde{G} = |G| I = (-K)^l I$. Here the
square matrix $G$ is linear in the total energy E and all momenta, $\tilde G$
is the matrix adjoint of $G$, $I$ is the identity matrix, $|G|$ is the
determinant of $G$, $l$ is a positive integer and $K=H-E$ is Lanczos' extended
Hamiltonian where $H$ is the classical Hamiltonian of the electro-mechanical
system. $K$ is identically zero for all such systems, so that matrix $G$ is
singular. As a consequence there always exists a vector function
$\underline\theta$ with the property $G\underline\theta=0$. This factorization
to obtain the matrix $G$ and vector function $\underline\theta$ is illustrated
first for a one-dimensional particle in a simple potential well. This same
technique, when applied to the classical nonrelativistic Hamiltonian for $N$
interacting particles in an electromagnetic field, is shown to yield for N=1
the Pauli wave equation with spin and its generalization to $N$ particles.
Finally this nonrelativistic generalization of the Pauli equation is used to
treat the simple Zeeman effect of a hydrogen-like atom as a two-particle
problem with spin.
| [
{
"version": "v1",
"created": "Thu, 11 Jan 2007 07:06:16 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Reed",
"Irving S.",
"",
"University of Southern California"
],
[
"Brun",
"Todd A.",
"",
"University of Southern California"
]
]
|
quant-ph/0701059 | Eric Charron | Sebastien Saugout (PPM, SPAM), Christian Cornaggia (SPAM), Annick
Suzor-Weiner (PPM), Eric Charron (PPM) | Ultrafast electro-nuclear dynamics of H2 double ionization | null | Physical Review Letters 98, 25 (2007) 253003 | 10.1103/PhysRevLett.98.253003 | null | quant-ph | null | The ultrafast electronic and nuclear dynamics of H2 laser-induced double
ionization is studied using a time-dependent wave packet approach that goes
beyond the fixed nuclei approximation. The double ionization pathways are
analyzed by following the evolution of the total wave function during and after
the pulse. The rescattering of the first ionized electron produces a coherent
superposition of excited molecular states which presents a pronounced transient
H+H- character. This attosecond excitation is followed by field-induced double
ionization and by the formation of short-lived autoionizing states which decay
via double ionization. These two double ionization mechanisms may be identified
by their signature imprinted in the kinetic-energy distribution of the ejected
protons.
| [
{
"version": "v1",
"created": "Thu, 11 Jan 2007 10:20:31 GMT"
},
{
"version": "v2",
"created": "Fri, 12 Jan 2007 16:58:04 GMT"
},
{
"version": "v3",
"created": "Tue, 20 Mar 2007 10:44:51 GMT"
}
]
| 2011-11-09T00:00:00 | [
[
"Saugout",
"Sebastien",
"",
"PPM, SPAM"
],
[
"Cornaggia",
"Christian",
"",
"SPAM"
],
[
"Suzor-Weiner",
"Annick",
"",
"PPM"
],
[
"Charron",
"Eric",
"",
"PPM"
]
]
|
quant-ph/0701060 | Archan S. Majumdar | Md. Manirul Ali, Dipankar Home, A. S. Majumdar, Alok K. Pan | Quantum time of flight distribution for cold trapped atoms | 6 pages, RevTex, 4 eps figures | Phys. Rev. A 75, 042110 (2007) | 10.1103/PhysRevA.75.042110 | null | quant-ph | null | The time of flight distribution for a cloud of cold atoms falling freely
under gravity is considered. We generalise the probability current density
approach to calculate the quantum arrival time distribution for the mixed state
describing the Maxwell-Boltzmann distribution of velocities for the falling
atoms. We find an empirically testable difference between the time of flight
distribution calculated using the quantum probability current and that obtained
from a purely classical treatment which is usually employed in analysing time
of flight measurements. The classical time of flight distribution matches with
the quantum distribution in the large mass and high temperature limits.
| [
{
"version": "v1",
"created": "Thu, 11 Jan 2007 13:11:44 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Ali",
"Md. Manirul",
""
],
[
"Home",
"Dipankar",
""
],
[
"Majumdar",
"A. S.",
""
],
[
"Pan",
"Alok K.",
""
]
]
|
quant-ph/0701061 | Marco Cozzini | P. Zanardi, P. Giorda, and M. Cozzini | The differential information-geometry of quantum phase transitions | 4 pages, 1 figure | null | null | null | quant-ph | null | The manifold of coupling constants parametrizing a quantum Hamiltonian is
equipped with a natural Riemannian metric with an operational
distinguishability content. We argue that the singularities of this metric are
in correspondence with the quantum phase transitions featured by the
corresponding system. This approach provides a universal conceptual framework
to study quantum critical phenomena which is differential-geometric and
information-theoretic at the same time.
| [
{
"version": "v1",
"created": "Thu, 11 Jan 2007 14:50:36 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Zanardi",
"P.",
""
],
[
"Giorda",
"P.",
""
],
[
"Cozzini",
"M.",
""
]
]
|
quant-ph/0701062 | J\"urgen Stockburger | J\"urgen T. Stockburger | Superdecoherence through gate control noise | null | null | null | null | quant-ph | null | The external control circuits of quantum gates inevitably introduce a small
but finite noise to the operation of quantum computers. The complex modes of
decoherence introduced by this noise are not covered by the common error
models. Using the controlled-phase gate as an example, the effect of gate
control noise on decoherence is investigated for different quantum computer
architectures. It is shown that the decoherence rate rises faster than linearly
with the length of a quantum register for most cases considered, adding to the
challenge of implementing proposed error correcting and fault tolerant
computation schemes. Sometimes an unwanted effective inter-qubit coupling
associated with the noise appears.
| [
{
"version": "v1",
"created": "Thu, 11 Jan 2007 15:18:15 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Stockburger",
"Jürgen T.",
""
]
]
|
quant-ph/0701063 | Metin Aktas | Metin Aktas | Exact Bound State Solutions of the Schrodinger Equation for Noncentral
Potential via the Nikiforov-Uvarov Method | 10 pages | Int. J. Theor. Phys. 48, 2154 (2009) | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Exact bound state solutions of the Schrodinger equation for generalized
noncentral potential are examined by means of the Nikiforov-Uvarov method. The
wavefunctions and the corresponding energy eigenvalues of the system are
obtained analytically. The results examined for the potential are compatible
with those obtained by the other methods.
| [
{
"version": "v1",
"created": "Thu, 11 Jan 2007 15:47:45 GMT"
},
{
"version": "v2",
"created": "Mon, 23 Apr 2007 20:37:41 GMT"
},
{
"version": "v3",
"created": "Thu, 9 Jul 2009 22:56:40 GMT"
}
]
| 2009-07-10T00:00:00 | [
[
"Aktas",
"Metin",
""
]
]
|
quant-ph/0701064 | Graeme Mitchison | Graeme Mitchison | A dual de Finetti theorem | 12 pages, 1 figure | null | null | null | quant-ph | null | The quantum de Finetti theorem says that, given a symmetric state, the state
obtained by tracing out some of its subsystems approximates a convex sum of
power states. The more subsystems are traced out, the better this approximation
becomes. Schur-Weyl duality suggests that there ought to be a dual result that
applies to a unitarily invariant state rather than a symmetric state. Instead
of tracing out a number of subsystems, one traces out part of every subsystem.
The theorem then asserts that the resulting state approximates the fully mixed
state, and the larger the dimension of the traced-out part of each subsystem,
the better this approximation becomes. This paper gives a number of
propositions together with their dual versions, to show how far the duality
holds.
| [
{
"version": "v1",
"created": "Thu, 11 Jan 2007 15:57:47 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Mitchison",
"Graeme",
""
]
]
|
quant-ph/0701065 | Graeme Smith | John A. Smolin, Graeme Smith, Stephanie Wehner | A simple family of nonadditive quantum codes | 3 pages, new version with slight clarifications, no results are
changed | Phys. Rev. Lett. 99, 130505 (2007) | 10.1103/PhysRevLett.99.130505 | null | quant-ph | null | Most known quantum codes are additive, meaning the codespace can be described
as the simultaneous eigenspace of an abelian subgroup of the Pauli group. While
in some scenarios such codes are strictly suboptimal, very little is understood
about how to construct nonadditive codes with good performance. Here we present
a family of nonadditive quantum codes for all odd blocklengths, n, that has a
particularly simple form. Our codes correct single qubit erasures while
encoding a higher dimensional space than is possible with an additive code or,
for n of 11 or greater, any previous codes.
| [
{
"version": "v1",
"created": "Thu, 11 Jan 2007 21:18:43 GMT"
},
{
"version": "v2",
"created": "Tue, 20 Mar 2007 20:55:51 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Smolin",
"John A.",
""
],
[
"Smith",
"Graeme",
""
],
[
"Wehner",
"Stephanie",
""
]
]
|
quant-ph/0701066 | David Kielpinski | D. Kielpinski | Mesoscopic entanglement of noninteracting qubits using collective
spontaneous emission | replaced; corrected per referee comments | New J. Phys. 9, 408 (2007) | 10.1088/1367-2630/9/11/408 | null | quant-ph | null | We describe an experimentally straightforward method for preparing an
entangled W state of up to 100 qubits. Our repeat-until-success protocol relies
on detection of single photons from collective spontaneous emission in free
space. Our method allows entanglement preparation in a wide range of qubit
implementations that lack entangling qubit-qubit interactions. We give detailed
numerical examples for entanglement of neutral atoms in optical lattices and of
nitrogen-vacancy centres in diamond. The simplicity of our method should enable
preparation of mesoscopic entangled states in a number of physical systems in
the near future.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 02:00:57 GMT"
},
{
"version": "v2",
"created": "Thu, 28 Jun 2007 23:18:11 GMT"
}
]
| 2011-01-25T00:00:00 | [
[
"Kielpinski",
"D.",
""
]
]
|
quant-ph/0701067 | Hoshang Heydari | Hoshang Heydari | Entanglement witnesses and concurrence for multi-qubit states | 5 pages | Quantum Information and Computation 8(8/9) (2008) 0791-0796 | null | null | quant-ph | null | We establish a relation between concurrence and entanglement witnesses. In
particular, we construct entanglement witnesses for three-qubit W and GHZ
states in terms of concurrence and different set of operators that generate it.
We also generalize our construction for multi-qubit states.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 05:52:00 GMT"
}
]
| 2008-06-05T00:00:00 | [
[
"Heydari",
"Hoshang",
""
]
]
|
quant-ph/0701068 | Peter Rohde | Peter P. Rohde, Sean D. Barrett | Strategies for the preparation of large cluster states using
non-deterministic gates | 9 pages, 7 figures | New J. Phys 9, 198 (2007) | 10.1088/1367-2630/9/6/198 | null | quant-ph | null | The cluster state model for quantum computation has paved the way for schemes
that allow scalable quantum computing, even when using non-deterministic
quantum gates. Here the initial step is to prepare a large entangled state
using non-deterministic gates. A key question in this context is the relative
efficiencies of different `strategies', i.e. in what order should the
non-deterministic gates be applied, in order to maximize the size of the
resulting cluster states? In this paper we consider this issue in the context
of `large' cluster states. Specifically, we assume an unlimited resource of
qubits and ask what the steady state rate at which `large' clusters are
prepared from this resource is, given an entangling gate with particular
characteristics. We measure this rate in terms of the number of entangling gate
operations that are applied. Our approach works for a variety of different
entangling gate types, with arbitrary failure probability. Our results indicate
that strategies whereby one preferentially bonds together identical qubits are
considerably more efficient than those in which one does not. Additionally,
compared to earlier analytic results, our numerical study offers substantially
improved resource scaling.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 07:10:17 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Rohde",
"Peter P.",
""
],
[
"Barrett",
"Sean D.",
""
]
]
|
quant-ph/0701069 | Shao-Ming Fei | Zong-Guo Li, Shao-Ming Fei, Zhi-Xi Wang and Ke Wu | Entanglement conditions for multi-mode states | 12 pages | Phys. Rev. A 75(2007)012311 | 10.1103/PhysRevA.75.012311 | null | quant-ph | null | We provide a class of inequalities for detecting entanglements in multi-mode
systems. Necessary conditions for fully separable, bi-separable and sufficient
conditions for fully entangled states are explicitly presented.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 09:26:23 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Li",
"Zong-Guo",
""
],
[
"Fei",
"Shao-Ming",
""
],
[
"Wang",
"Zhi-Xi",
""
],
[
"Wu",
"Ke",
""
]
]
|
quant-ph/0701070 | Boris Samsonov F | Boris F. Samsonov and V. V. Shamshutdinova | Towards Dynamical Qubit Controlling with Time-Dependent External Fields | 5 pages, 9 figures | J. Phys. A: Math. Theor. 41 (2008) 244023 (9pp) | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For a flux qubit described by a two-level system of equations we propose a
special time dependent external control field. We show that for a qubit placed
in this field there exists a critical value of tunnel frequency. When the
tunnel frequency is close to its critical value, the probability value of a
definite direction of the current circulating in a Josephson-junction circuit
may be kept above 1/2 during a desirable time interval. We also show that such
a behavior is not much affected by a sufficiently small dissipation.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 10:01:11 GMT"
},
{
"version": "v2",
"created": "Thu, 19 Feb 2009 10:58:38 GMT"
}
]
| 2009-02-19T00:00:00 | [
[
"Samsonov",
"Boris F.",
""
],
[
"Shamshutdinova",
"V. V.",
""
]
]
|
quant-ph/0701071 | Marco Genovese | Marco Genovese | Research on Hidden Variable Theories: a review of recent progresses | version without figures | Physics Reports 413 (2005) 319 | 10.1016/j.physrep.2005.03.003 | null | quant-ph | null | Quantum Mechanics (QM) is one of the pillars of modern physics: an impressive
amount of experiments have confirmed this theory and many technological
applications are based on it. Nevertheless, at one century since its
development, various aspects concerning its very foundations still remain to be
clarified. Among them, the transition from a microscopic probabilistic world
into a macroscopic deterministic one and quantum non-locality. A possible way
out from these problems would be if QM represents a statistical approximation
of an unknown deterministic theory.
This review is addressed to present the most recent progresses on the studies
related to Hidden Variable Theories (HVT), both from an experimental and a
theoretical point of view, giving a larger emphasis to results with a direct
experimental application.
More in details, the first part of the review is a historical introduction to
this problem. The Einstein-Podolsky-Rosen argument and the first discussions
about HVT are introduced, describing the fundamental Bell's proposal for a
general experimental test of every Local HVT and the first attempts to realise
it.
The second part of the review is devoted to elucidate the recent progresses
toward a conclusive Bell inequalities experiment obtained with entangled
photons and other physical systems.
Finally, the last sections are targeted to shortly discuss Non-Local HVT.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 10:03:01 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Genovese",
"Marco",
""
]
]
|
quant-ph/0701072 | Shao-Ming Fei | Shao-Ming Fei | A Note on Pseudo-Hermitian Systems with Point Interactions and Quantum
Separability | 6 pages | Czech J. Phys. 56(2006)887-892 | 10.1007/s10582-006-0384-z | null | quant-ph | null | We study the quantum entanglement and separability of Hermitian and
pseudo-Hermitian systems of identical bosonic or fermionic particles with point
interactions. The separability conditions are investigated in detail.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 10:54:02 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Fei",
"Shao-Ming",
""
]
]
|
quant-ph/0701073 | Mikio Kozuma | K. Akiba, K. Kashiwagi, T. Yonehara, and M. Kozuma | Frequency filtered storage of parametric fluorescence with
electromagnetically induced transparency | null | Physical Review A 76, 023812 (2007) | 10.1103/PhysRevA.76.023812 | null | quant-ph | null | The broadband parametric fluorescence pulse (probe light) with center
frequency resonant on 87Rb D1 line was injected into a cold atomic ensemble
with coherent light (control light). Due to the low gain in the parametric down
conversion process, the probe light was in a highly bunched photon-pair state.
By switching off the control light, the probe light within the
electromagnetically induced transparency window was mapped on the atoms. When
the control light was switched on, the probe light was retrieved and frequency
filtered storage was confirmed from the superbunching effect and an increase of
the coherence time of the retrieved light.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 11:25:24 GMT"
},
{
"version": "v2",
"created": "Sat, 26 May 2007 11:47:55 GMT"
},
{
"version": "v3",
"created": "Thu, 28 Jun 2007 07:22:58 GMT"
},
{
"version": "v4",
"created": "Sun, 27 Jan 2008 11:51:50 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Akiba",
"K.",
""
],
[
"Kashiwagi",
"K.",
""
],
[
"Yonehara",
"T.",
""
],
[
"Kozuma",
"M.",
""
]
]
|
quant-ph/0701074 | Gerardo Adesso | Gerardo Adesso, Ivette Fuentes-Schuller, Marie Ericsson | Continuous variable entanglement sharing in non-inertial frames | 19 pages, 13 EPS figures (most low-res due to oversize); terminology
revised | Phys.Rev.A76:062112,2007 | 10.1103/PhysRevA.76.062112 | null | quant-ph cond-mat.stat-mech gr-qc hep-th | null | We study the distribution of entanglement between modes of a free scalar
field from the perspective of observers in uniform acceleration. We consider a
two-mode squeezed state of the field from an inertial perspective, and
analytically study the degradation of entanglement due to the Unruh effect, in
the cases of either one or both observers undergoing uniform acceleration. We
find that for two observers undergoing finite acceleration, the entanglement
vanishes between the lowest frequency modes. The loss of entanglement is
precisely explained as a redistribution of the inertial entanglement into
multipartite quantum correlations among accessible and unaccessible modes from
a non-inertial perspective. We show that classical correlations are also lost
from the perspective of two accelerated observers but conserved if one of the
observers remains inertial.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 14:15:25 GMT"
},
{
"version": "v2",
"created": "Mon, 5 Feb 2007 19:00:26 GMT"
},
{
"version": "v3",
"created": "Fri, 26 Oct 2007 10:33:02 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Adesso",
"Gerardo",
""
],
[
"Fuentes-Schuller",
"Ivette",
""
],
[
"Ericsson",
"Marie",
""
]
]
|
quant-ph/0701075 | Riccardo Franco | Riccardo Franco | Wigner-function description of EPR experiment | 8 pages | null | null | null | quant-ph | null | We provide a detailed description of the EPR paradox (in the Bohm version)
for a two qubit-state in the discrete Wigner function formalism. We compare the
probability distributions for two qubit relevant to simultaneously-measurable
observables (computed from the Wigner function) with the probability
distributions representing two perfectly-correlated classic particles in a
discrete phase-space. We write in both cases the updating formulae after a
measure, thus obtaining a mathematical definition of \textit{classic collapse}
and \textit{quantum collapse}. We study, with the EPR experiment, the joint
probability distributions of Alice's and Bob's qubit before and after the
measure, analyzing the non-local effects. In particular, we give a more precise
definition of locality, which we call m-locality: we show that quantum systems
may violate this kind of locality, thus preserving, in an EPR-like argument,
the completeness of Quantum Mechanics.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 13:37:31 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Franco",
"Riccardo",
""
]
]
|
quant-ph/0701076 | Naomichi Hatano | Naomichi Hatano, Ryoen Shirasaki, Hiroaki Nakamura | Non-Abelian gauge field theory of the spin-orbit interaction and a
perfect spin filter | 8 pages, 9 figures, to appear in Phys. Rev. A | Phys.Rev.A75:032107,2007 | 10.1103/PhysRevA.75.032107 | null | quant-ph cond-mat.mes-hall | null | We point out that the Rashba and Dresselhaus spin-orbit interactions in two
dimensions can be regarded as a Yang-Mills non-Abelian gauge field. The
physical field generated by the gauge field gives the electron wave function a
spin-dependent phase which is frequently called the Aharonov-Casher phase.
Applying on an AB ring this non-Abelian field together with the usual vector
potential, we can make the interference condition completely destructive for
one component of the spin while completely constructive for the other component
of the spin over the entire energy range. This enables us to construct a
perfect spin filter.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 13:53:38 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Hatano",
"Naomichi",
""
],
[
"Shirasaki",
"Ryoen",
""
],
[
"Nakamura",
"Hiroaki",
""
]
]
|
quant-ph/0701077 | Shi-Jian Gu | Wen-Long You, Ying-Wai Li, and Shi-Jian Gu | Fidelity, dynamic structure factor, and susceptibility in critical
phenomena | 4 pages, 2 figures, final version accepted by PRE | Phys. Rev. E 76, 022101 (2007) | 10.1103/PhysRevE.76.022101 | null | quant-ph | null | Motivated by the growing importance of fidelity in quantum critical
phenomena, we establish a general relation between fidelity and structure
factor of the driving term in a Hamiltonian through a newly introduced concept:
fidelity susceptibility. Our discovery, as shown by some examples, facilitates
the evaluation of fidelity in terms of susceptibility using well developed
techniques such as density matrix renormalization group for the ground state,
or Monte Carlo simulations for the states in thermal equilibrium.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 16:44:49 GMT"
},
{
"version": "v2",
"created": "Thu, 21 Jun 2007 02:26:18 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"You",
"Wen-Long",
""
],
[
"Li",
"Ying-Wai",
""
],
[
"Gu",
"Shi-Jian",
""
]
]
|
quant-ph/0701078 | Matteo G. A. Paris | Matteo G. A. Paris | Input-output relations for multiport ring cavities | 6 pages, 5 figures (low-res) | J. Phys. B 40, F63 (2007). | 10.1088/0953-4075/40/4/F03 | null | quant-ph | null | Quantum input-output relations for a generic $n$-port ring cavity are
obtained by modeling the ring as a cascade of $n$ interlinked beam splitters.
Cavity response to a beam impinging on one port is studied as a function of the
beam-splitter reflectivities and the internal phase-shifts. Interferometric
sensitivity and stability are analyzed as a function of the number of ports.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 19:04:51 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Paris",
"Matteo G. A.",
""
]
]
|
quant-ph/0701079 | Ting Gao | Feng-Li Yan, Ting Gao, You-Cheng Li | An Implementation of a Positive Operator Valued Measure | 4 pages, no figure | Chin. Phys. Lett., 24 (2007) 322 | null | null | quant-ph | null | An implementation of the positive operator valued measure (POVM) is given. By
using this POVM one can realize the probabilistic teleportation of an unknown
two-particle state.
| [
{
"version": "v1",
"created": "Fri, 12 Jan 2007 19:14:02 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Yan",
"Feng-Li",
""
],
[
"Gao",
"Ting",
""
],
[
"Li",
"You-Cheng",
""
]
]
|
quant-ph/0701080 | Xiong-Jun Liu | Xiao-Ting Zhou, Xiong-Jun Liu, Hui Jing, C. H. Lai and C. H. Oh | Manipulating Quantum States of Molecules Created via Photoassociation of
Bose-Einstein Condensates | 4 Pages, 1 figure | null | null | null | quant-ph | null | We show the quantum state transfer technique in two-color photoassociation
(PA) of a Bose-Einstein condensate, where a quantized field is used to couple
the free-bound transition from atom state to excited molecular state. Under the
weak excitation condition, we find that quantum states of the quantized field
can be transferred to the created molecular condensate. The feasibility of this
technique is confirmed by considering the atomic and molecular decays
discovered in the current PA experiments. The present results allow us to
manipulate quantum states of molecules in the photoassociation of a
Bose-Einstein condensate.
| [
{
"version": "v1",
"created": "Sun, 14 Jan 2007 11:36:31 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Zhou",
"Xiao-Ting",
""
],
[
"Liu",
"Xiong-Jun",
""
],
[
"Jing",
"Hui",
""
],
[
"Lai",
"C. H.",
""
],
[
"Oh",
"C. H.",
""
]
]
|
quant-ph/0701081 | Hefeng Wang | Hefeng Wang and Sabre Kais | Quantum Entanglement and Electron Correlation in Molecular Systems | 18 pages, 2 figures, change typoes | null | null | null | quant-ph | null | We study the relation between quantum entanglement and electron correlation
in quantum chemistry calculations. We prove that the Hartree-Fock (HF) wave
function does not violate Bell's inequality, thus is not entangled while the
configuration interaction (CI) wave function is entangled since it violates
Bell's inequality. Entanglement is related to electron correlation and might be
used as an alternative measure of the electron correlation in quantum chemistry
calculations. As an example we show the calculations of entanglement for the
H$_2$ molecule and how it is related to electron correlation of the system,
which is the difference between the exact and the HF energies.
| [
{
"version": "v1",
"created": "Sat, 13 Jan 2007 17:57:45 GMT"
},
{
"version": "v2",
"created": "Mon, 25 Jun 2007 20:11:27 GMT"
}
]
| 2007-06-25T00:00:00 | [
[
"Wang",
"Hefeng",
""
],
[
"Kais",
"Sabre",
""
]
]
|
quant-ph/0701082 | Steven Teerenstra | S. Teerenstra | Wave-particle duality in the damped harmonic oscillator | MSc thesis in Theoretical Physics. 109 pages. Related to the lecture
notes quant-ph/0411024 | null | null | null | quant-ph | null | Quantization of the damped harmonic oscillator is taken as leitmotiv to
gently introduce elements of quantum probability theory for physicists. To this
end, we take (graduate) students in physics as entry level and explain the
physical intuition and motivation behind the, sometimes overwhelming, math
machinery of quantum probability theory.
The main text starts with the quantization of the (undamped) harmonic
oscillator from the Heisenberg and Schroedinger point of view. We show how both
treatments are special instances of a quantum probabilistic quantization
procedure: the second quantization functor. We then apply the second
quantization functor to the damped harmonic oscillator and interpret the
quantum dynamics of the position and energy operator as stochastic processes.
| [
{
"version": "v1",
"created": "Sat, 13 Jan 2007 18:55:47 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Teerenstra",
"S.",
""
]
]
|
quant-ph/0701083 | Daniela Dragoman | Daniela Dragoman | Evidence Against Klein Paradox in Graphene | Revised version 2 new pages added, new abstract, and title | null | null | null | quant-ph | null | It is demonstrated that both transmission and reflection coefficients
associated to the Klein paradox at a step barrier are positive and less than
unity, so that the particle-antiparticle pair creation mechanism commonly
linked to this phenomenon is not necessary. Because graphene is a solid-state
testing ground for quantum electrodynamics phenomena involving massless Dirac
fermions we suggest that the transport characteristic through a p-n graphene
junction can decide between the results obtained in this paper and the common
Klein paradox theory, which imply negative transmission and higher-than-unity
reflection coefficients. Recent experimental evidence supports our findings.
| [
{
"version": "v1",
"created": "Sat, 13 Jan 2007 18:53:09 GMT"
},
{
"version": "v2",
"created": "Sun, 4 Nov 2007 08:19:43 GMT"
},
{
"version": "v3",
"created": "Sat, 23 Feb 2008 19:04:08 GMT"
}
]
| 2008-02-23T00:00:00 | [
[
"Dragoman",
"Daniela",
""
]
]
|
quant-ph/0701084 | William E. Baylis | R. Cabrera, W. E. Baylis | Average Fidelity in n-Qubit systems | 4 pages, no figures. Revision includes additional references and a
more detailed symmetry argument | null | 10.1016/j.physleta.2007.03.068 | null | quant-ph | null | This letter generalizes the expression for the average fidelity of single
qubits, as found by Bowdrey et al., to the case of n qubits. We use a simple
algebraic approach with basis elements for the density-matrix expansion
expressed as Kronecker products of n Pauli spin matrices. An explicit
integration over initial states is avoided by invoking the invariance of the
state average under unitary transformations of the initial density matrix. The
results have applications to measurements of quantum information, for example
in ion-trap and NMR experiments.
| [
{
"version": "v1",
"created": "Sat, 13 Jan 2007 21:13:06 GMT"
},
{
"version": "v2",
"created": "Wed, 7 Mar 2007 21:48:01 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Cabrera",
"R.",
""
],
[
"Baylis",
"W. E.",
""
]
]
|
quant-ph/0701085 | Ward Struyve | S. Colin, W. Struyve | A Dirac sea pilot-wave model for quantum field theory | 41 pages, no figures, LaTex, v2 minor improvements and additions | J. Phys. A 40, 7309-7342 (2007) | 10.1088/1751-8113/40/26/015 | null | quant-ph hep-th | null | We present a pilot-wave model for quantum field theory in which the Dirac sea
is taken seriously. The model ascribes particle trajectories to all the
fermions, including the fermions filling the Dirac sea. The model is
deterministic and applies to the regime in which fermion number is
superselected. This work is a further elaboration of work by Colin, in which a
Dirac sea pilot-wave model is presented for quantum electrodynamics. We extend
his work to non-electromagnetic interactions, we discuss a cut-off
regularization of the pilot-wave model and study how it reproduces the standard
quantum predictions. The Dirac sea pilot-wave model can be seen as a possible
continuum generalization of a lattice model by Bell. It can also be seen as a
development and generalization of the ideas by Bohm, Hiley and Kaloyerou, who
also suggested the use of the Dirac sea for the development of a pilot-wave
model for quantum electrodynamics.
| [
{
"version": "v1",
"created": "Sun, 14 Jan 2007 03:22:33 GMT"
},
{
"version": "v2",
"created": "Tue, 3 Jul 2007 08:01:06 GMT"
}
]
| 2008-12-27T00:00:00 | [
[
"Colin",
"S.",
""
],
[
"Struyve",
"W.",
""
]
]
|
quant-ph/0701086 | Luzh | Jingfu Zhang, Xinhua Peng, Nageswaran Rajendran, and Dieter Suter | Effect of system level structure and spectral distribution of the
environment on the decoherence rate | Generalizations are added. Comments are welcome | Phys. Rev. A 75, 042314 (2007) | 10.1103/PhysRevA.75.042314 | null | quant-ph | null | Minimizing the effect of decoherence on a quantum register must be a central
part of any strategy to realize scalable quantum information processing. Apart
from the strength of the coupling to the environment, the decoherence rate is
determined by the the system level structure and by the spectral composition of
the noise trace that the environment generates. Here, we discuss a relatively
simple model that allows us to study these different effects quantitatively in
detail. We evaluate the effect that the perturbation has on an NMR system while
it performs a Grover search algorithm.
| [
{
"version": "v1",
"created": "Sun, 14 Jan 2007 21:41:16 GMT"
},
{
"version": "v2",
"created": "Tue, 27 Feb 2007 09:14:53 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Zhang",
"Jingfu",
""
],
[
"Peng",
"Xinhua",
""
],
[
"Rajendran",
"Nageswaran",
""
],
[
"Suter",
"Dieter",
""
]
]
|
quant-ph/0701087 | Anders M{\aa}nsson | A. M{\aa}nsson, P. G. L. Porta Mana, G. Bj\"ork | Numerical Bayesian quantum-state assignment for a three-level quantum
system. II. Average-value data with a constant, a Gaussian-like, and a Slater
prior | 10 pages, 4 figures. V2: added "Post scriptum" under Conclusions,
slightly changed Acknowledgements, and corrected some spelling errors | null | null | null | quant-ph | null | This paper offers examples of concrete numerical applications of Bayesian
quantum-state assignment methods to a three-level quantum system. The
statistical operator assigned on the evidence of various measurement data and
kinds of prior knowledge is computed partly analytically, partly through
numerical integration (in eight dimensions) on a computer. The measurement data
consist in the average of outcome values of N identical von Neumann projective
measurements performed on N identically prepared three-level systems. In
particular the large-N limit will be considered. Three kinds of prior knowledge
are used: one represented by a plausibility distribution constant in respect of
the convex structure of the set of statistical operators; another one
represented by a prior studied by Slater, which has been proposed as the
natural measure on the set of statistical operators; the last prior is
represented by a Gaussian-like distribution centred on a pure statistical
operator, and thus reflecting a situation in which one has useful prior
knowledge about the likely preparation of the system. The assigned statistical
operators obtained with the first two kinds of priors are compared with the one
obtained by Jaynes' maximum entropy method for the same measurement situation.
In the companion paper the case of measurement data consisting in absolute
frequencies is considered.
| [
{
"version": "v1",
"created": "Mon, 15 Jan 2007 14:49:05 GMT"
},
{
"version": "v2",
"created": "Tue, 16 Jan 2007 15:02:06 GMT"
}
]
| 2016-08-14T00:00:00 | [
[
"Månsson",
"A.",
""
],
[
"Mana",
"P. G. L. Porta",
""
],
[
"Björk",
"G.",
""
]
]
|
quant-ph/0701088 | Andrew P. Hines | Andrew P. Hines and P.C.E. Stamp | Quantum Walks, Quantum Gates and Quantum Computers | 17 pages, 10 figures | null | 10.1103/PhysRevA.75.062321 | null | quant-ph | null | The physics of quantum walks on graphs is formulated in Hamiltonian language,
both for simple quantum walks and for composite walks, where extra discrete
degrees of freedom live at each node of the graph. It is shown how to map
between quantum walk Hamiltonians and Hamiltonians for qubit systems and
quantum circuits; this is done for both a single- and multi-excitation coding,
and for more general mappings. Specific examples of spin chains, as well as
static and dynamic systems of qubits, are mapped to quantum walks, and walks on
hyperlattices and hypercubes are mapped to various gate systems. We also show
how to map a quantum circuit performing the quantum Fourier transform, the key
element of Shor's algorithm, to a quantum walk system doing the same. The
results herein are an essential preliminary to a Hamiltonian formulation of
quantum walks in which coupling to a dynamic quantum environment is included.
| [
{
"version": "v1",
"created": "Sun, 14 Jan 2007 22:30:27 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Hines",
"Andrew P.",
""
],
[
"Stamp",
"P. C. E.",
""
]
]
|
quant-ph/0701089 | Matteo G. A. Paris | Alessandro Ferraro, Matteo G A Paris | Joint measurements on qubits and cloning of observables | 7 pages, 1 figure, to appear on Open System & Inf. Dynamics | Open Syst. & Inf. Dyn. 14, 149 (2007) | null | null | quant-ph | null | Cloning of observables, unlike standard cloning of states, aims at copying
the information encoded in the statistics of a class of observables rather then
on quantum states themselves. In such a process the emphasis is on the quantum
operation (evolution plus measurement) necessary to retrieve the original
information. We analyze, for qubit systems, the cloning of a class generated by
two noncommuting observables, elucidating the relationship between such a
process and joint measurements. This helps in establishing an optimality
criterion for cloning of observables. We see that, even if the cloning machine
is designed to act on the whole class generated by two noncommuting
observables, the same optimal performances of a joint measurement can be
attained. Finally, the connection with state dependent cloning is enlightened.
| [
{
"version": "v1",
"created": "Sun, 14 Jan 2007 23:22:12 GMT"
}
]
| 2007-08-08T00:00:00 | [
[
"Ferraro",
"Alessandro",
""
],
[
"Paris",
"Matteo G A",
""
]
]
|
quant-ph/0701090 | Peter Rohde | Peter P. Rohde, Timothy C. Ralph, William J. Munro | Error propagation in loss- and failure-tolerant quantum computation
schemes | 8 pages, 4 figures | null | null | null | quant-ph | null | Qubit loss and gate failure are significant obstacles for the implementation
of scalable quantum computation. Recently there have been several proposals for
overcoming these problems, including schemes based on parity and cluster
states. While effective at dealing with loss and gate failure, these schemes
typically lead to a blow-out in effective depolarizing noise rates. In this
supplementary paper we present a detailed analysis of this problem and
techniques for minimizing it.
| [
{
"version": "v1",
"created": "Sun, 14 Jan 2007 23:31:25 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Rohde",
"Peter P.",
""
],
[
"Ralph",
"Timothy C.",
""
],
[
"Munro",
"William J.",
""
]
]
|
quant-ph/0701091 | Ya Cao | Ya Cao, An-Min Wang, Xiao-San Ma and Ning-bo Zhao | Multi-particle and High-dimension Controlled Order Rearrangement
Encryption Protocols | null | null | 10.1140/epjd/e2007-00237-y | null | quant-ph | null | Based on the controlled order rearrange encryption (CORE) for quantum key
distribution using EPR pairs[Fu.G.Deng and G.L.Long Phys.Rev.A68 (2003)
042315], we propose the generalized controlled order rearrangement encryption
(GCORE) protocols of $N$ qubits and $N$ qutrits, concretely display them in the
cases using 3-qubit, 2-qutrit maximally entangled basis states. We further
indicate that our protocols will become safer with the increase of number of
particles and dimensions. Moreover, we carry out the security analysis using
quantum covariant cloning machine for the protocol using qutrits. Although the
applications of the generalized scheme need to be further studied, the GCORE
has many distinct features such as great capacity and high efficiency.
| [
{
"version": "v1",
"created": "Sun, 14 Jan 2007 23:47:36 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Cao",
"Ya",
""
],
[
"Wang",
"An-Min",
""
],
[
"Ma",
"Xiao-San",
""
],
[
"Zhao",
"Ning-bo",
""
]
]
|
quant-ph/0701092 | Kazuyuki Fujii | Kazuyuki Fujii (Yokohama City University) | Exponentiation of certain Matrices related to the Four Level System by
use of the Magic Matrix | Latex ; 13 pages ; 2 figures ; substantial changes (including the
title) made. To appear in Yokohama Mathematical Journal (2007) | Yokohama Math. J. 54(2007) 31-44 | null | null | quant-ph math-ph math.MP | null | In this paper we show how to calculate explicitly the exponential of certain
matrices, which are evolution operators governing the interaction of the four
level system of atoms and the radiation, etc. We present a consistent method in
terms of the magic matrix by Makhlin.
As a closely related subject, we derive a closed form expression of the
Baker-Campbell-Hausdorff formula for a class of matrices in SU(4), by use of
the method developed by the present authors in quant-ph/0610009.
| [
{
"version": "v1",
"created": "Mon, 15 Jan 2007 01:43:50 GMT"
},
{
"version": "v2",
"created": "Mon, 22 Jan 2007 00:08:21 GMT"
},
{
"version": "v3",
"created": "Thu, 30 Aug 2007 05:46:26 GMT"
}
]
| 2008-02-29T00:00:00 | [
[
"Fujii",
"Kazuyuki",
"",
"Yokohama City University"
]
]
|
quant-ph/0701093 | Zhe Sun | Zhe Sun, Xiaoguang Wang, Y.B.Gao, C.P.Sun | Decoherence in time evolution of bound entanglement | 9 pages, 8 figures | Eur. Phys. J. D 46, 521-530 (2008) | 10.1140/epjd/e2007-00319-x | null | quant-ph | null | We study a dynamic process of disentanglement by considering the time
evolution of bound entanglement for a quantum open system, two qutrits coupling
to a common environment. Here, the initial quantum correlations of the two
qutrits are characterized by the bound entanglement. In order to show the
universality of the role of environment on bound entanglement, both bosonic and
spin environments are considered. We found that the bound entanglement displays
collapses and revivals, and it can be stable against small temperature and time
change. The thermal fluctuation effects on bound entanglement are also
considered.
| [
{
"version": "v1",
"created": "Mon, 15 Jan 2007 02:09:36 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Sun",
"Zhe",
""
],
[
"Wang",
"Xiaoguang",
""
],
[
"Gao",
"Y. B.",
""
],
[
"Sun",
"C. P.",
""
]
]
|
quant-ph/0701094 | Ulrich Hohenester | Ulrich Hohenester, Per Kristian Rekdal, Alfio Borzi, Joerg
Schmiedmayer | Optimal quantum control of Bose Einstein condensates in magnetic
microtraps | 11 pages, 7 figures | Phys. Rev.A 75, 023602 (2007) | 10.1103/PhysRevA.75.023602 | null | quant-ph | null | Transport of Bose-Einstein condensates in magnetic microtraps, controllable
by external parameters such as wire currents or radio-frequency fields, is
studied within the framework of optimal control theory (OCT). We derive from
the Gross-Pitaevskii equation the optimality system for the OCT fields that
allow to efficiently channel the condensate between given initial and desired
states. For a variety of magnetic confinement potentials we study transport and
wavefunction splitting of the condensate, and demonstrate that OCT allows to
drastically outperfrom more simple schemes for the time variation of the
microtrap control parameters.
| [
{
"version": "v1",
"created": "Mon, 15 Jan 2007 08:14:42 GMT"
}
]
| 2008-02-15T00:00:00 | [
[
"Hohenester",
"Ulrich",
""
],
[
"Rekdal",
"Per Kristian",
""
],
[
"Borzi",
"Alfio",
""
],
[
"Schmiedmayer",
"Joerg",
""
]
]
|
quant-ph/0701095 | Sergei Kukhlevsky V | S.V. Kukhlevsky | Interference-induced enhancement of intensity and energy of a multimode
quantum optical field by a subwavelength array of coherent light sources | A revised version of MS | null | 10.1007/s00340-008-3200-6 | null | quant-ph math-ph math.MP physics.optics | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, we have showed a mechanism that could provide a great transmission
enhancement of the light waves passed through subwavelength aperture arrays in
thin metal films not by the plasmon-polariton waves, but by the constructive
interference of diffracted waves (beams generated by the apertures) at the
detector placed in the far-field zone. We now present a quantum reformulation
of the model. The Hamiltonian describing the interference-induced enhancement
of the intensity and energy of a multimode quantum optical field is derived.
Such a field can be produced, for instance, by a subwavelength array of
coherent light sources.
| [
{
"version": "v1",
"created": "Mon, 15 Jan 2007 10:38:53 GMT"
},
{
"version": "v2",
"created": "Wed, 17 Jan 2007 10:12:44 GMT"
},
{
"version": "v3",
"created": "Fri, 19 Jan 2007 11:37:33 GMT"
},
{
"version": "v4",
"created": "Mon, 22 Jan 2007 15:57:27 GMT"
},
{
"version": "v5",
"created": "Fri, 23 Feb 2007 16:09:01 GMT"
},
{
"version": "v6",
"created": "Fri, 13 Jun 2008 13:41:52 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Kukhlevsky",
"S. V.",
""
]
]
|
quant-ph/0701096 | Sangchul Oh | Sangchul Oh | Entanglement and Quantum Phase Transitions via Adiabatic Quantum
Computation | Revised | Eur. Phys. J. D 58, 409 (2010) | 10.1140/epjd/e2010-00105-9 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For a finite XY chain and a finite two-dimensional Ising lattice, it is shown
that the paramagnetic ground state is adiabatically transformed to the GHZ
state in the ferromagnetic phase by slowly turning on the magnetic field. The
fidelity between the GHZ state and an adiabatically evolved state shows a
feature of the quantum phase transition.
| [
{
"version": "v1",
"created": "Mon, 15 Jan 2007 10:35:50 GMT"
},
{
"version": "v2",
"created": "Fri, 30 Oct 2009 22:27:24 GMT"
}
]
| 2010-07-26T00:00:00 | [
[
"Oh",
"Sangchul",
""
]
]
|
quant-ph/0701097 | Gerard Hooft 't | Gerard 't Hooft | The Free-Will Postulate in Quantum Mechanics | 8 pages, 1 figure | null | null | ITP-UU-07/4, SPIN-07/4 | quant-ph | null | The so-called "free will axiom" is an essential ingredient in many
discussions concerning hidden variables in quantum mechanics. In this paper we
argue that "free will" can be defined in different ways. The definition usually
employed is clearly invalid in strictly deterministic theories. A different,
more precise formulation is proposed here, defining a condition that may well
be a more suitable one to impose on theoretical constructions and models. Our
axiom, to be referred to as the `unconstrained initial state' condition, has
consequences similar to "free will", but does not clash with determinism, and
appears to lead to different conclusions concerning causality and locality in
quantum mechanics. Models proposed earlier by this author fall in this
category. Imposing our `unconstrained initial state' condition on a
deterministic theory underlying Quantum Mechanics, appears to lead to a
restricted free-will condition in the quantum system: an observer has the free
will to modify the setting of a measuring device, but has no control over the
phase of its wave function. The dismissal of the usual "free will" concept does
not have any consequences for our views and interpretations of human activities
in daily life, and the way our minds function, but it requires a more careful
discussion on what, in practice, free will actually amounts to.
| [
{
"version": "v1",
"created": "Mon, 15 Jan 2007 14:09:55 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Hooft",
"Gerard 't",
""
]
]
|
quant-ph/0701098 | Richard A. Mould | Richard A Mould | Optical Shelving: Suppressed Fluorescence | 5 pages, 0 figures | null | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The shelving phenomenon of quantum optics, originally observed by Dehmelt, is
analyzed in terms of the qRules that are given in another paper. The heuristic
value of these rules is apparent because they not only describe the dark period
during shelving, but they reveal the mechanism that enforces the suppression of
fluorescence during that time.
| [
{
"version": "v1",
"created": "Mon, 15 Jan 2007 15:31:02 GMT"
},
{
"version": "v2",
"created": "Mon, 11 Apr 2011 20:29:58 GMT"
}
]
| 2011-04-13T00:00:00 | [
[
"Mould",
"Richard A",
""
]
]
|
quant-ph/0701099 | Ya Cao | Ya Cao, An Min Wang | Revised Geometric Measure of Entanglement | 35 pages, 8 figures | null | null | null | quant-ph | null | We present an revised geometric measure of entanglement (RGME). The revised
version is an entanglement monotone. Some useful inequalities about RGME are
deduced. For exemplification, we give the formulas of RGME for the
two-parameter class of states in $2 \otimes n$ quantum system, the two
particles high dimensional maximally entangled mixed state, the isotropic state
including $n$-particle $d$-level case and two multipartite bound entangled
states. The result shows there is a relation $\widetilde{E}_{\sin^2} \leq
E_{re}$, which indicates that the RGME is an appropriate measure of
entanglement.
| [
{
"version": "v1",
"created": "Mon, 15 Jan 2007 15:32:10 GMT"
},
{
"version": "v2",
"created": "Thu, 25 Jan 2007 22:26:54 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Cao",
"Ya",
""
],
[
"Wang",
"An Min",
""
]
]
|
quant-ph/0701100 | Gondran Michel | M.Gondran, M. Bozic, D. Arsenovic, A. Gondran | Proposed experiment with Rydberg atoms to test the wave function
interpretation | 10 pages, 5 figures, submited to "Foundations of Physics" | Acta Physica Polonica A, vol. 112 (2008) | null | null | quant-ph | null | Experiment{Fabre_1983} shows that Rydberg atoms do not pass through 1
micronmeter width slits if their principal quantum number is rather large(n >
60). Thus, the particle density measured after the slits is null while the wave
function calculated after the slits is not. This experiment is in contradiction
with the Born interpretation (the square of the wave function is proportional
to the probability density for the particle to be found at each point in
space). The classical interpretation of this experiment, which removes the
contradiction, is to suppose that if the particles do not pass, the wave
function does not pass either (classical assumption).
An alternative interpretation of this experiment is to suppose that the wave
function passes through the slits, but that the Born interpretation is not
valid any more in this case (alternative assumption).
The aim of this paper is to present an experiment testing this alternative
assumption compared to the classical assumption.
| [
{
"version": "v1",
"created": "Mon, 15 Jan 2007 15:47:10 GMT"
}
]
| 2011-03-24T00:00:00 | [
[
"Gondran",
"M.",
""
],
[
"Bozic",
"M.",
""
],
[
"Arsenovic",
"D.",
""
],
[
"Gondran",
"A.",
""
]
]
|
quant-ph/0701101 | Vlatko Vedral | Vlatko Vedral | Quantumness without quantumness: entanglement as classical correlations
in higher dimensions | 6 pages, no figures, special issue of Journal of Modern Optics in
honour of Peter Knight | null | 10.1080/09500340701266922 | null | quant-ph | null | I exploit the formal equivalence between the ground state of a $d$
dimensional quantum system and a d+1 dimensional classical Ising chain to
represent quantum entanglement in terms of classical correlations only. This
offers a general "local hidden variable model" for all quantum phenomena
existing in one dimension lower than the (hidden variable) classical model
itself. The local hidden variable model is not contradicted by the implications
of Bell's theorem. Formal theory is presented first and then exemplified by the
quantum Ising spin chain in a transverse magnetic field. Here I explicitely
show how to derive any two site entanglement in the transverse model from the
partition function of the classical Ising spin chain existing in two
dimensions. Some speculations are then presented regarding possible fundamental
implications of these results.
| [
{
"version": "v1",
"created": "Mon, 15 Jan 2007 19:42:53 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Vedral",
"Vlatko",
""
]
]
|
quant-ph/0701102 | Rochus Klesse | Rochus Klesse | Approximate quantum error correction, random codes, and quantum channel
capacity | 29 pages, final version to appear in Phys. Rev. A, improved lower
bound for code entanglement fidelity, simplified proof | Phys. Rev. A 75, 062315 (2007) | 10.1103/PhysRevA.75.062315 | null | quant-ph cond-mat.other | null | We work out a theory of approximate quantum error correction that allows us
to derive a general lower bound for the entanglement fidelity of a quantum
code. The lower bound is given in terms of Kraus operators of the quantum
noise. This result is then used to analyze the average error correcting
performance of codes that are randomly drawn from unitarily invariant code
ensembles. Our results confirm that random codes of sufficiently large block
size are highly suitable for quantum error correction. Moreover, employing a
lemma of Bennett, Shor, Smolin, and Thapliyal, we prove that random coding
attains information rates of the regularized coherent information.
| [
{
"version": "v1",
"created": "Mon, 15 Jan 2007 20:56:36 GMT"
},
{
"version": "v2",
"created": "Wed, 6 Jun 2007 17:31:25 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Klesse",
"Rochus",
""
]
]
|
quant-ph/0701103 | Richard Jozsa | Sean Clark, Richard Jozsa and Noah Linden | Generalised Clifford groups and simulation of associated quantum
circuits | 21 pages | null | null | null | quant-ph | null | Quantum computations that involve only Clifford operations are classically
simulable despite the fact that they generate highly entangled states; this is
the content of the Gottesman-Knill theorem. Here we isolate the ingredients of
the theorem and provide generalisations of some of them with the aim of
identifying new classes of simulable quantum computations. In the usual
construction, Clifford operations arise as projective normalisers of the first
and second tensor powers of the Pauli group. We consider replacing the Pauli
group by an arbitrary finite subgroup G of U(d). In particular we seek G such
that G tensor G has an entangling normaliser. Via a generalisation of the
Gottesman-Knill theorem the resulting normalisers lead to classes of quantum
circuits that can be classically efficiently simulated. For the qubit case d=2
we exhaustively treat all finite subgroups of U(2) and find that the only ones
(up to unitary equivalence and trivial phase extensions) with entangling
normalisers are the groups G_n generated by X and the n^th root of Z.
| [
{
"version": "v1",
"created": "Mon, 15 Jan 2007 21:44:44 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Clark",
"Sean",
""
],
[
"Jozsa",
"Richard",
""
],
[
"Linden",
"Noah",
""
]
]
|
quant-ph/0701104 | Olivier Pfister | Olivier Pfister | Graph states and carrier-envelope phase squeezing | null | null | null | null | quant-ph | null | We outline a new class of continuous-variable graph states that can be useful
to describe entangle- ment, and also multimode squeezing, in an optical
frequency comb. We show that a particular case of such states coincides with
the squeezing of the carrier-envelope phase, or of the total intensity, of a
mode-locked laser. We then discuss the experimental issues related to measuring
the quantum noise of the carrier-envelope phase of a frequency comb and show
that this can be carried out by use of quantum heterodyne multiplexing, a
technique that may be useful to measure multipartite entanglement as well.
| [
{
"version": "v1",
"created": "Tue, 16 Jan 2007 01:17:45 GMT"
},
{
"version": "v2",
"created": "Sat, 7 Jul 2007 16:26:51 GMT"
}
]
| 2007-07-07T00:00:00 | [
[
"Pfister",
"Olivier",
""
]
]
|
quant-ph/0701105 | Kevin O'Donnell | Kevin A. O'Donnell and Alfred B. U'Ren | Observation of ultra-broadband, beamlike parametric downconversion | Optics Letters, accepted, 4 pages and 2 figures | null | 10.1364/OL.32.000817 | null | quant-ph | null | We report spontaneous parametric downconversion having an unusually wide
spectral bandwidth. A collinear type-1 phase-matching configuration is employed
with degeneracy near the zero group velocity dispersion frequency. With a
spectral width of 1080 nm and degenerate wavelength 1885 nm, the source also
emits a high flux of photon pairs constrained to a cone of only 2 degree
half-angle. A rigorous theoretical approach is developed that confirms the
experimental observations. The source properties are consistent with an
ultra-short photon-pair correlation time and, for a narrowband pump, extremely
high-dimensional spectral entanglement.
| [
{
"version": "v1",
"created": "Tue, 16 Jan 2007 04:26:31 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"O'Donnell",
"Kevin A.",
""
],
[
"U'Ren",
"Alfred B.",
""
]
]
|
quant-ph/0701106 | Eduardo Sergio Santini | E. Sergio Santini | Might EPR particles communicate through a wormhole? | Corrected version, to appears in EPL | Europhys.Lett.78:30005,2007 | 10.1209/0295-5075/78/30005 | null | quant-ph gr-qc | null | We consider the two-particle wave function of an Einstein-Podolsky-Rosen
system, given by a two dimensional relativistic scalar field model. The Bohm-de
Broglie interpretation is applied and the quantum potential is viewed as
modifying the Minkowski geometry. In this way an effective metric, which is
analogous to a black hole metric in some limited region, is obtained in one
case and a particular metric with singularities appears in the other case,
opening the possibility, following Holland, of interpreting the EPR
correlations as being originated by an effective wormhole geometry, through
which the physical signals can propagate.
| [
{
"version": "v1",
"created": "Tue, 16 Jan 2007 05:30:01 GMT"
},
{
"version": "v2",
"created": "Sat, 24 Mar 2007 17:59:18 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Santini",
"E. Sergio",
""
]
]
|
quant-ph/0701107 | Robert Lompay | Denys Bondar | Applications of The Information Model of The Collapse Phenomena: The
Mathematical Model of Everett's Worlds in The Case of The Measurement of A
Spin 1/2 Projection | revtex4, 13 pages, 5 figures | null | null | null | quant-ph | null | The information model of the collapse phenomena is further advanced. We
discover an important property of the model - the death point effect. The P
function approach is presented to construct the manifest form of the function
of risk. We clarify a close connection of the model with the Extended Everett
Concept. The model is also reformulated as an automaton. Examples are
considered.
| [
{
"version": "v1",
"created": "Tue, 16 Jan 2007 06:03:26 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Bondar",
"Denys",
""
]
]
|
quant-ph/0701108 | Petrus H Potgieter | Willem Fouch\'e, Johannes Heidema, Glyn Jones, Petrus H. Potgieter
(University of South Africa) | Deutsch's Universal Quantum Turing Machine (Revisited) | 7 pages | null | null | null | quant-ph | null | Deutsch, Feynman, and Manin viewed quantum computing as a kind of universal
physical simulation procedure. Much of the writing about quantum Turing
machines has shown how these machines can simulate an arbitrary unitary
transformation on a finite number of qubits. This interesting problem has been
addressed most famously in a paper by Deutsch, and later by Bernstein and
Vazirani. Quantum Turing machines form a class closely related to deterministic
and probabilistic Turing machines and one might hope to find a universal
machine in this class. A universal machine is the basis of a notion of
programmability. The extent to which universality has in fact been established
by the pioneers in the field is examined and a key notion in theoretical
computer science (universality) is scrutinised. In a forthcoming paper, the
authors will also consider universality in the quantum gate model.
| [
{
"version": "v1",
"created": "Tue, 16 Jan 2007 10:59:54 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Fouché",
"Willem",
"",
"University of South Africa"
],
[
"Heidema",
"Johannes",
"",
"University of South Africa"
],
[
"Jones",
"Glyn",
"",
"University of South Africa"
],
[
"Potgieter",
"Petrus H.",
"",
"University of South Africa"
]
]
|
quant-ph/0701109 | Tabish Qureshi | Tabish Qureshi (Centre for Theoretical Physics, J.M.I., New Delhi) | Modified Two-Slit Experiments and Complementarity | Revised version, to appear in J. Quantum Inf. Sci | Journal of Quantum Information Science, 2, 34-39 (2012) | 10.4236/jqis.2012.22007 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Some modified two-slit interference experiments claim to demonstrate a
violation of Bohr's complementarity principle. A typical such experiment is
theoretically analyzed using wave-packet dynamics. The flaw in the analysis of
such experiments is pointed out and it is demonstrated that they do not violate
complementarity. In addition, it is quite generally proved that if the state of
a particle is such that the modulus square of the wave-function yields an
interference pattern, then it necessarily loses which-path information.
| [
{
"version": "v1",
"created": "Tue, 16 Jan 2007 11:30:41 GMT"
},
{
"version": "v2",
"created": "Fri, 19 Jan 2007 10:30:04 GMT"
},
{
"version": "v3",
"created": "Wed, 2 May 2012 12:33:55 GMT"
}
]
| 2012-06-25T00:00:00 | [
[
"Qureshi",
"Tabish",
"",
"Centre for Theoretical Physics, J.M.I., New Delhi"
]
]
|
quant-ph/0701110 | Jennifer Sebby-Strabley | J. Sebby-Strabley, B. L. Brown, M. Anderlini, P. J. Lee, P. R.
Johnson, W. D. Phillips, and J. V. Porto | Preparing and probing atomic number states with an atom interferometer | null | Phys. Rev. Lett. 98 200405 (2007) | 10.1103/PhysRevLett.98.200405 | null | quant-ph | null | We describe the controlled loading and measurement of number-squeezed states
and Poisson states of atoms in individual sites of a double well optical
lattice. These states are input to an atom interferometer that is realized by
symmetrically splitting individual lattice sites into double wells, allowing
atoms in individual sites to evolve independently. The two paths then
interfere, creating a matter-wave double-slit diffraction pattern. The time
evolution of the double-slit diffraction pattern is used to measure the number
statistics of the input state. The flexibility of our double well lattice
provides a means to detect the presence of empty lattice sites, an important
and so far unmeasured factor in determining the purity of a Mott state.
| [
{
"version": "v1",
"created": "Tue, 16 Jan 2007 14:14:41 GMT"
},
{
"version": "v2",
"created": "Thu, 2 Aug 2007 18:45:29 GMT"
}
]
| 2007-08-02T00:00:00 | [
[
"Sebby-Strabley",
"J.",
""
],
[
"Brown",
"B. L.",
""
],
[
"Anderlini",
"M.",
""
],
[
"Lee",
"P. J.",
""
],
[
"Johnson",
"P. R.",
""
],
[
"Phillips",
"W. D.",
""
],
[
"Porto",
"J. V.",
""
]
]
|
quant-ph/0701111 | Ting Yu | M. Yonac, Ting Yu and J. H. Eberly | Pairwise Concurrence Dynamics: A Four-Qubit Model | 9 pages, 12 figures, v3 with minor changes | J. Phys. B 40, S45 (2007) | 10.1088/0953-4075/40/9/S02 | null | quant-ph | null | We examine entanglement dynamics via concurrence among four two-state systems
labeled $A, ~a, ~B, ~b$. The four systems are arranged on an addressable
"lattice" in such a way that $A$ and $a$ at one location labeled $Aa$ can
interact with each other via excitation exchange, and the same for $B$ and $b$
at location $Bb$. The $Aa$ location is prepared entangled with the $Bb$
location, but their mutual complete isolation prevents interaction in the
interval between actions of an external addressing agent. There are six
pairwise concurrences on the lattice, and we follow their evolution in the
interval between external actions. We show how entanglement evolves and may
exhibit the non-analytic effect termed entanglement sudden death (ESD), with
periodic recovery. These loss and gain processes may be interpreted as
entanglement transfer between the subsystems.
| [
{
"version": "v1",
"created": "Tue, 16 Jan 2007 16:20:16 GMT"
},
{
"version": "v2",
"created": "Wed, 21 Feb 2007 18:51:59 GMT"
},
{
"version": "v3",
"created": "Fri, 26 Oct 2007 19:54:27 GMT"
}
]
| 2011-11-09T00:00:00 | [
[
"Yonac",
"M.",
""
],
[
"Yu",
"Ting",
""
],
[
"Eberly",
"J. H.",
""
]
]
|
quant-ph/0701112 | Daniel Gottesman | Daniel Gottesman | Fault-Tolerant Quantum Computation | 6 pages, prepared for special issue of Physics in Canada. v2 has typo
corrections, and minor clarifications and updates to text and references | null | null | null | quant-ph | null | I give a brief overview of fault-tolerant quantum computation, with an
emphasis on recent work and open questions.
| [
{
"version": "v1",
"created": "Tue, 16 Jan 2007 17:14:14 GMT"
},
{
"version": "v2",
"created": "Thu, 30 Aug 2007 21:07:32 GMT"
}
]
| 2007-08-31T00:00:00 | [
[
"Gottesman",
"Daniel",
""
]
]
|
quant-ph/0701113 | Daniel Lehmann | Daniel Lehmann | A presentation of Quantum Logic based on an "and then" connective | 28 pages. Submitted | Journal of Logic and Computation 18 (1): 59-76 Feb. 2008 | 10.1093/logcom/exm054 | Short version in Leibniz Center, School of Engineering, Hebrew U.
TR-2007-1 | quant-ph cs.LO math.LO | null | When a physicist performs a quantic measurement, new information about the
system at hand is gathered. This paper studies the logical properties of how
this new information is combined with previous information. It presents Quantum
Logic as a propositional logic under two connectives: negation and the "and
then" operation that combines old and new information. The "and then"
connective is neither commutative nor associative. Many properties of this
logic are exhibited, and some small elegant subset is shown to imply all the
properties considered. No independence or completeness result is claimed.
Classical physical systems are exactly characterized by the commutativity, the
associativity, or the monotonicity of the "and then" connective. Entailment is
defined in this logic and can be proved to be a partial order. In orthomodular
lattices, the operation proposed by Finch (1969) satisfies all the properties
studied in this paper. All properties satisfied by Finch's operation in modular
lattices are valid in Hilbert Space Quantum Logic. It is not known whether all
properties of Hilbert Space Quantum Logic are satisfied by Finch's operation in
modular lattices. Non-commutative, non-associative algebraic structures
generalizing Boolean algebras are defined, ideals are characterized and a
homomorphism theorem is proved.
| [
{
"version": "v1",
"created": "Tue, 16 Jan 2007 17:55:20 GMT"
}
]
| 2008-02-24T00:00:00 | [
[
"Lehmann",
"Daniel",
""
]
]
|
quant-ph/0701114 | Alex Hayat | Alex Hayat, Pavel Ginzburg and Meir Orenstein | Two-Photon Emission from Semiconductors | Coincidence experiment results added, QW stimulated TPE added,
stimulation power TPE dependence shown, measured spectra recalibrated,
quantitative theory presented | null | null | null | quant-ph | null | We report the first experimental observations of two-photon emission from
semiconductors, to the best of our knowledge, and develop a corresponding
theory for the room-temperature process. Spontaneous two-photon emission is
demonstrated in optically-pumped bulk GaAs and in electrically-driven
GaInP/AlGaInP quantum wells. Singly-stimulated two-photon emission measurements
demonstrate the theoretically predicted two-photon optical gain in
semiconductors - a necessary ingredient for any realizations of future
two-photon semiconductor lasers. Photon-coincidence experiment validates the
simultaneity of the electrically-driven GaInP/AlGaInP two-photon emission,
limited only by detector's temporal resolution.
| [
{
"version": "v1",
"created": "Tue, 16 Jan 2007 19:23:56 GMT"
},
{
"version": "v2",
"created": "Fri, 25 May 2007 22:01:09 GMT"
},
{
"version": "v3",
"created": "Thu, 25 Oct 2007 12:50:11 GMT"
}
]
| 2007-10-25T00:00:00 | [
[
"Hayat",
"Alex",
""
],
[
"Ginzburg",
"Pavel",
""
],
[
"Orenstein",
"Meir",
""
]
]
|
quant-ph/0701115 | Alexander Russell | Cristopher Moore, Alexander Russell and Umesh Vazirani | A classical one-way function to confound quantum adversaries | null | null | null | null | quant-ph | null | The promise of quantum computation and its consequences for
complexity-theoretic cryptography motivates an immediate search for
cryptosystems which can be implemented with current technology, but which
remain secure even in the presence of quantum computers. Inspired by recent
negative results pertaining to the nonabelian hidden subgroup problem, we
present here a classical algebraic function $f_V(M)$ of a matrix $M$ which we
believe is a one-way function secure against quantum attacks. Specifically,
inverting $f_V$ reduces naturally to solving a hidden subgroup problem over the
general linear group (which is at least as hard as the hidden subgroup problem
over the symmetric group). We also demonstrate a reduction from Graph
Isomorphism to the problem of inverting $f_V$; unlike Graph Isomorphism,
however, the function $f_V$ is random self-reducible and therefore uniformly
hard.
These results suggest that, unlike Shor's algorithm for the discrete
logarithm--which is, so far, the only successful quantum attack on a classical
one-way function--quantum attacks based on the hidden subgroup problem are
unlikely to work. We also show that reconstructing any entry of $M$, or the
trace of $M$, with nonnegligible advantage is essentially as hard as inverting
$f_V$. Finally, $f_V$ can be efficiently computed and the number of output bits
is less than $1+\epsilon$ times the number of input bits for any $\epsilon >
0$.
| [
{
"version": "v1",
"created": "Wed, 17 Jan 2007 01:21:34 GMT"
},
{
"version": "v2",
"created": "Fri, 19 Jan 2007 21:01:09 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Moore",
"Cristopher",
""
],
[
"Russell",
"Alexander",
""
],
[
"Vazirani",
"Umesh",
""
]
]
|
quant-ph/0701116 | Wang Zhi Yong | Zhi-Yong Wang, Cai-Dong Xiong | Relativistic free-motion time-of-arrival | 16 pages, no figure. Revised version | J.Phys.A40:1897-1905,2007 | 10.1088/1751-8113/40/8/014 | null | quant-ph | null | Relativistic free-motion time-of-arrival theory for massive spin-1/2
particles is systematically developed. Contrary to the nonrelativistic
time-of-arrival operator studied thoroughly in previous literatures, the
relativistic time-of-arrival operator possesses self-adjoint extensions because
of the particle-antiparticle symmetry. The nonrelativistic limit of our theory
is in agreement with the nonrelativistic time-of-arrival theory. By comparing
the time-of-arrival operator with the Hamiltonian operator of a free Dirac
particle, one can show a duality between position space and momentum space.
| [
{
"version": "v1",
"created": "Wed, 17 Jan 2007 02:52:51 GMT"
},
{
"version": "v2",
"created": "Mon, 22 Oct 2007 09:06:46 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Wang",
"Zhi-Yong",
""
],
[
"Xiong",
"Cai-Dong",
""
]
]
|
quant-ph/0701117 | Martin Varbanov | Martin Varbanov, Todd A. Brun | Decomposing generalized measurements into continuous stochastic
processes | 9 pages, LaTeX, name changed, typos corrected | Phys. Rev. A 76, 032104 (2007) | 10.1103/PhysRevA.76.032104 | null | quant-ph | null | One of the broadest concepts of measurement in quantum theory is the
generalized measurement. Another paradigm of measurement--arising naturally in
quantum optics, among other fields--is that of continuous-time measurements,
which can be seen as the limit of a consecutive sequence of weak measurements.
They are naturally described in terms of stochastic processes, or
time-dependent random variables. We show that any generalized measurement can
be decomposed as a sequence of weak measurements with a mathematical limit as a
continuous stochastic process. We give an explicit construction for any
generalized measurement, and prove that the resulting continuous evolution, in
the long-time limit, collapses the state of the quantum system to one of the
final states generated by the generalized measurement, being decomposed, with
the correct probabilities. A prominent feature of the construction is the
presence of a feedback mechanism--the instantaneous choice weak measurement at
a given time depends on the outcomes of earlier measurements. For a generalized
measurement with $n$ outcomes, this information is captured by a real
$n$-vector on an $n$-simplex, which obeys a simple classical stochastic
evolution.
| [
{
"version": "v1",
"created": "Wed, 17 Jan 2007 04:05:06 GMT"
},
{
"version": "v2",
"created": "Thu, 14 Jun 2007 01:07:39 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Varbanov",
"Martin",
""
],
[
"Brun",
"Todd A.",
""
]
]
|
quant-ph/0701118 | Bernhard Meister | Bernhard K. Meister | The Lueders Postulate and the Distinguishability of Observables | Submitted to the proceedings of ICFNCS, Hong Kong, 2006 | International Journal of Modern Physics B 21, no. 23n24 (2007):
4293-4297 | 10.1142/S0217979207045566 | null | quant-ph | null | The Lueders postulate is reviewed and implications for the distinguishability
of observables are discussed. As an example the distinguishability of two
similar observables for spin-1/2 particles is described. Implementation issues
are briefly analyzed.
| [
{
"version": "v1",
"created": "Wed, 17 Jan 2007 08:28:20 GMT"
}
]
| 2016-11-01T00:00:00 | [
[
"Meister",
"Bernhard K.",
""
]
]
|
quant-ph/0701119 | An Min Wang | An Min Wang | Entanglement versus observables | 4.3 pages, 8 figures, Revised figure captions | null | null | null | quant-ph | null | A general scheme to seek for the relations between entanglement and
bservables is proposed in principle. In two-qubit systems with enough general
Hamiltonian, we find the entanglement to be the functions of observables for
six kinds of chosen state sets and verify how these functions be invariant with
time evolution. Moreover, we demonstrate and illustrate the cases with
entanglement versus a set of commutable observables under eight kinds of given
initial states. Our conclusions show how entanglement become observable even
measurable by experiment, and they are helpful for understanding of the nature
of entanglement in physics.
| [
{
"version": "v1",
"created": "Wed, 17 Jan 2007 11:51:56 GMT"
},
{
"version": "v2",
"created": "Thu, 18 Jan 2007 02:38:32 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Wang",
"An Min",
""
]
]
|
quant-ph/0701120 | Rolf Heidemann | Rolf Heidemann, Ulrich Raitzsch, Vera Bendkowsky, Bj\"orn Butscher,
Robert L\"ow, Luis Santos and Tilman Pfau | Evidence for coherent collective Rydberg excitation in the strong
blockade regime | 5 pages, 4 figures | Phys. Rev. Lett. 99, 163601 (2007) | 10.1103/PhysRevLett.99.163601 | null | quant-ph | null | Blockade effects on the single quantum level are at the heart of quantum
devices like single-electron transistors. The blockade mechanisms are based on
strong interactions like the Coulomb interaction in case of single electrons.
Neutral atoms excited into a Rydberg state experience abnormally strong
interactions that lead to the corresponding blockade effect for Rydberg atoms.
In this paper we report on our measurements of a strong van der Waals blockade,
showing that only one out of several thousand atoms within a blockade volume
can be excited. In addition, our experimental results demonstrate the coherent
nature of the excitation of magnetically trapped ultracold atoms into a Rydberg
state, confirming the predicted dependence of the collective Rabi frequency on
the square root of the mesoscopic system size. This collective coherent
behaviour is generic for all mesoscopic systems which are able to carry only
one single excitation quantum.
| [
{
"version": "v1",
"created": "Wed, 17 Jan 2007 12:43:28 GMT"
},
{
"version": "v2",
"created": "Tue, 19 Jun 2007 18:02:23 GMT"
}
]
| 2007-10-16T00:00:00 | [
[
"Heidemann",
"Rolf",
""
],
[
"Raitzsch",
"Ulrich",
""
],
[
"Bendkowsky",
"Vera",
""
],
[
"Butscher",
"Björn",
""
],
[
"Löw",
"Robert",
""
],
[
"Santos",
"Luis",
""
],
[
"Pfau",
"Tilman",
""
]
]
|
quant-ph/0701121 | Stefano Longhi | G. Della Valle, M. Ornigotti, E. Cianci, V. Foglietti, P. Laporta, S.
Longhi | Visualization of Coherent Destruction of Tunneling in an Optical Double
Well System | final version | Phys. Rev. Lett. 98, 263601 (2007) | 10.1103/PhysRevLett.98.263601 | null | quant-ph | null | We report on a direct visualization of coherent destruction of tunneling
(CDT) of light waves in a double well system which provides an optical analog
of quantum CDT as originally proposed by Grossmann, Dittrich, Jung, and Hanggi
[Phys. Rev. Lett. {\bf 67}, 516 (1991)]. The driven double well, realized by
two periodically-curved waveguides in an Er:Yb-doped glass, is designed so that
spatial light propagation exactly mimics the coherent space-time dynamics of
matter waves in a driven double-well potential governed by the Schr\"{o}dinger
equation. The fluorescence of Er ions is exploited to image the spatial
evolution of light in the two wells, clearly demonstrating suppression of light
tunneling for special ratios between frequency and amplitude of the driving
field.
| [
{
"version": "v1",
"created": "Wed, 17 Jan 2007 14:40:11 GMT"
},
{
"version": "v2",
"created": "Fri, 29 Jun 2007 08:00:04 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Della Valle",
"G.",
""
],
[
"Ornigotti",
"M.",
""
],
[
"Cianci",
"E.",
""
],
[
"Foglietti",
"V.",
""
],
[
"Laporta",
"P.",
""
],
[
"Longhi",
"S.",
""
]
]
|
quant-ph/0701122 | William Hall | Paul Butterley, William Hall | Numerical evidence for the maximum number of mutually unbiased bases in
dimension six | 4 pages, 2 figures, some minor changes made | null | 10.1016/j.physleta.2007.04.059 | null | quant-ph | null | The question of determining the maximal number of mutually unbiased bases in
dimension six has received much attention since their introduction to quantum
information theory, but a definitive answer has still not been found. In this
paper we move away from the traditional analytic approach and use a numerical
approach to attempt to determine this number. We numerically minimise a
non-negative function of a set of N+1 orthonormal bases in dimension d which
only evaluates to zero if the bases are mutually unbiased. As a result we find
strong evidence that (as has been conjectured elsewhere) there are no more than
three mutually unbiased bases in dimension six.
| [
{
"version": "v1",
"created": "Wed, 17 Jan 2007 16:00:19 GMT"
},
{
"version": "v2",
"created": "Tue, 13 Mar 2007 12:03:36 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Butterley",
"Paul",
""
],
[
"Hall",
"William",
""
]
]
|
quant-ph/0701123 | Luis L. Sanchez. Soto | Ch. Marquardt, J. Heersink, R. Dong, M.V. Chekhova, A.B. Klimov, L.L.
Sanchez-Soto, U.L. Andersen, and G. Leuchs | Quantum reconstruction of an intense polarization squeezed optical state | 4 pages, 4 eps color figures | Phys. Rev. Lett. 99, 220401 (2007) | 10.1103/PhysRevLett.99.220401 | null | quant-ph | null | We perform a reconstruction of the polarization sector of the density matrix
of an intense polarization squeezed beam starting from a complete set of Stokes
measurements. By using an appropriate quasidistribution, we map this onto the
Poincare space providing a full quantum mechanical characterization of the
measured polarization state.
| [
{
"version": "v1",
"created": "Wed, 17 Jan 2007 16:41:21 GMT"
}
]
| 2008-07-25T00:00:00 | [
[
"Marquardt",
"Ch.",
""
],
[
"Heersink",
"J.",
""
],
[
"Dong",
"R.",
""
],
[
"Chekhova",
"M. V.",
""
],
[
"Klimov",
"A. B.",
""
],
[
"Sanchez-Soto",
"L. L.",
""
],
[
"Andersen",
"U. L.",
""
],
[
"Leuchs",
"G.",
""
]
]
|
quant-ph/0701124 | Lorenza Viola | Lorenza Viola, Howard Barnum | Entanglement and Subsystems, Entanglement beyond Subsystems, and All
That | 14 pages, no figures, RevTeX4. Invited contribution to the
Proceedings of the Boston Colloquium for Philosophy of Science on
``Foundations of Quantum Information and Entanglement'', Boston, March
23--24, 2006 | null | null | null | quant-ph | null | Entanglement plays a pervasive role nowadays throughout quantum information
science, and at the same time provides a bridging notion between quantum
information science and fields as diverse as condensed-matter theory, quantum
gravity, and quantum foundations. In recent years, a notion of ''Generalized
Entanglement'' (GE) has emerged, based on the idea that entanglement may be
directly defined through expectation values of preferred observables -- without
reference to a preferred subsystem decomposition. Preferred observables capture
the physically relevant point of view, as defined by dynamical, operational, or
fundamental constraints. While reducing to the standard entanglement notion
when preferred observables are restricted to arbitrary local observables acting
on individual subsystems, GE substantially expands subsystem-based entanglement
theories, in terms of both conceptual foundations and range of applicability.
Remarkably, the GE framework allows for non-trivial entanglement to exist
within a single, indecomposable quantum system, demands in general a
distinction between quantum separability and absence of entanglement, and
naturally extends to situations where existing approaches may not be directly
useful -- such as entanglement in arbitrary convex-cones settings and
entanglement for indistinguishable quantum particles. In this paper, we revisit
the main motivations leading to GE, and summarize the accomplishments and
prospects of the GE program to date, with an eye toward conceptual developments
and implications. In particular, we explain how the GE approach both shares
strong points of contact with abstract operational quantum theories and,
ultimately, calls for an observer-dependent redefinition of concepts like
locality, completeness, and reality in quantum theory.
| [
{
"version": "v1",
"created": "Wed, 17 Jan 2007 17:43:06 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Viola",
"Lorenza",
""
],
[
"Barnum",
"Howard",
""
]
]
|
quant-ph/0701125 | Oscar Dahlsten Mr | O.C.O. Dahlsten, R. Oliveira, M.B. Plenio | Emergence of typical entanglement in two-party random processes | 32 pages, 11 figures | J. Phys. A: Math. Theor. 40 (2007) 8081-8108 | 10.1088/1751-8113/40/28/S16 | null | quant-ph | null | We investigate the entanglement within a system undergoing a random, local
process. We find that there is initially a phase of very fast generation and
spread of entanglement. At the end of this phase the entanglement is typically
maximal. In previous work we proved that the maximal entanglement is reached to
a fixed arbitrary accuracy within $O(N^3)$ steps, where $N$ is the total number
of qubits. Here we provide a detailed and more pedagogical proof. We
demonstrate that one can use the so-called stabilizer gates to simulate this
process efficiently on a classical computer. Furthermore, we discuss three ways
of identifying the transition from the phase of rapid spread of entanglement to
the stationary phase: (i) the time when saturation of the maximal entanglement
is achieved, (ii) the cut-off moment, when the entanglement probability
distribution is practically stationary, and (iii) the moment block entanglement
scales exhibits volume scaling. We furthermore investigate the mixed state and
multipartite setting. Numerically we find that classical and quantum
correlations appear to behave similarly and that there is a well-behaved
phase-space flow of entanglement properties towards an equilibrium, We describe
how the emergence of typical entanglement can be used to create a much simpler
tripartite entanglement description. The results form a bridge between certain
abstract results concerning typical (also known as generic) entanglement
relative to an unbiased distribution on pure states and the more physical
picture of distributions emerging from random local interactions.
| [
{
"version": "v1",
"created": "Wed, 17 Jan 2007 17:48:28 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Dahlsten",
"O. C. O.",
""
],
[
"Oliveira",
"R.",
""
],
[
"Plenio",
"M. B.",
""
]
]
|
quant-ph/0701126 | Andris Ambainis | Andris Ambainis, Joseph Emerson | Quantum t-designs: t-wise independence in the quantum world | 19 pages, v2 two references added, to appear in Complexity'06 | null | null | null | quant-ph | null | A t-design for quantum states is a finite set of quantum states with the
property of simulating the Haar-measure on quantum states, w.r.t. any test that
uses at most t copies of a state. We give efficient constructions for
approximate quantum t-designs for arbitrary t. We then show that an approximate
4-design provides a derandomization of the state-distinction problem considered
by Sen (quant-ph/0512085), which is relevant to solving certain instances of
the hidden subgroup problem.
| [
{
"version": "v1",
"created": "Wed, 17 Jan 2007 20:20:39 GMT"
},
{
"version": "v2",
"created": "Tue, 6 Feb 2007 15:58:24 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Ambainis",
"Andris",
""
],
[
"Emerson",
"Joseph",
""
]
]
|
quant-ph/0701127 | Owen Maroney | O. J. E. Maroney | The Physical Basis of the Gibbs-von Neumann entropy | 42 pages, no figures (3rd version substantial revision and
simplification of central argument incorporating adiabatic availability and
passive distributions) | null | null | pi-foundqt-36 | quant-ph cond-mat.stat-mech | null | We develop the argument that the Gibbs-von Neumann entropy is the appropriate
statistical mechanical generalisation of the thermodynamic entropy, for
macroscopic and microscopic systems, whether in thermal equilibrium or not, as
a consequence of Hamiltonian dynamics. The mathematical treatment utilises well
known results [Gib02, Tol38, Weh78, Par89], but most importantly, incorporates
a variety of arguments on the phenomenological properties of thermal states
[Szi25, TQ63, HK65, GB91] and of statistical distributions[HG76, PW78, Len78].
This enables the identification of the canonical distribution as the unique
representation of thermal states without approximation or presupposing the
existence of an entropy function. The Gibbs-von Neumann entropy is then
derived, from arguments based solely on the addition of probabilities to
Hamiltonian dynamics.
| [
{
"version": "v1",
"created": "Wed, 17 Jan 2007 22:07:32 GMT"
},
{
"version": "v2",
"created": "Wed, 23 Jan 2008 04:52:13 GMT"
}
]
| 2008-01-23T00:00:00 | [
[
"Maroney",
"O. J. E.",
""
]
]
|
quant-ph/0701128 | Yuri A. Dabaghian | Yu. Dabaghian | Periodic orbit theory and spectral statistics for scaling quantum graphs | 24 pages, 5 figures | null | null | null | quant-ph | null | The explicit solution to the spectral problem of quantum graphs found
recently in \cite{Anima}, is used to produce the exact periodic orbit theory
description for the probability distributions of spectral statistics, including
the distribution for the nearest neighbor separations, $s_{n}=k_{n}-k_{n-1}$,
and the distribution of the spectral oscillations around the average, $\delta
k_{n}=k_{n}-\bar k_{n}$.
| [
{
"version": "v1",
"created": "Thu, 18 Jan 2007 00:11:59 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Dabaghian",
"Yu.",
""
]
]
|
quant-ph/0701129 | Jeremie Fulconis | J. Fulconis, O. Alibart, W. J. Wadsworth, and J. G. Rarity | Quantum interference with photon pairs using two micro-structured fibres | 14 pages, 9 figures | New J. Phys. 9 No 8 (August 2007) 276 | null | null | quant-ph | null | We demonstrate a quantum interference experiment between two photons coming
from non-degenerate pairs created by four-wave mixing in two separated
micro-structured fibres. When the two heralded photons are made
indistinguishable a 95% visibility is demonstrated.
| [
{
"version": "v1",
"created": "Thu, 18 Jan 2007 16:23:24 GMT"
}
]
| 2008-02-08T00:00:00 | [
[
"Fulconis",
"J.",
""
],
[
"Alibart",
"O.",
""
],
[
"Wadsworth",
"W. J.",
""
],
[
"Rarity",
"J. G.",
""
]
]
|
quant-ph/0701130 | Bo Sun | B. Sun, D. L. Zhou, L. You | Entanglement between two fermionic atoms inside a cylindrical harmonic
trap | to appear in PRA | null | 10.1103/PhysRevA.75.012332 | null | quant-ph | null | We investigate quantum entanglement between two (spin-1/2) fermions inside a
cylindrical harmonic trap, making use of the von Neumann entropy for the
reduced single particle density matrix as the pure state entanglement measure.
We explore the dependence of pair entanglement on the geometry and strength of
the trap and on the strength of the pairing interaction over the complete range
of the effective BCS to BEC crossover. Our result elucidates an interesting
connection between our model system of two fermions and that of two interacting
bosons.
| [
{
"version": "v1",
"created": "Thu, 18 Jan 2007 16:53:17 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Sun",
"B.",
""
],
[
"Zhou",
"D. L.",
""
],
[
"You",
"L.",
""
]
]
|
quant-ph/0701131 | Aurelian Isar | A. Isar, A. Sandulescu, W. Scheid | Dissipative tunneling through a parabolic potential in the Lindblad
theory of open quantum systems | 16 pages, 6 figures | Eur. Phys. J. D 12, 3 (2000) | 10.1007/s100530070035 | null | quant-ph | null | By using the Lindblad theory for open quantum systems, an analytical
expression of the tunneling probability through an inverted parabola is
obtained. This penetration probability depends on the environment coefficients.
It is shown that the tunneling probability increases with the dissipation and
the temperature of the thermal bath.
| [
{
"version": "v1",
"created": "Thu, 18 Jan 2007 11:18:08 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Isar",
"A.",
""
],
[
"Sandulescu",
"A.",
""
],
[
"Scheid",
"W.",
""
]
]
|
quant-ph/0701132 | Rami Pugatch | R. Pugatch, M. Shuker, O. Firstenberg, A. Ron, N. Davidson | Topological stability of stored optical vortices | 4 pages, 4 figures v2: minor grammatical corrections v3: problem with
references fixed v4: minor clarifications added to the text | Phys. Rev. Lett. 98, 203601 (2007) | 10.1103/PhysRevLett.98.203601 | null | quant-ph | null | We report an experiment in which an optical vortex is stored in a vapor of Rb
atoms. Due to its 2\pi phase twist, this mode, also known as the Laguerre-Gauss
mode, is topologically stable and cannot unwind even under conditions of strong
diffusion. To supplement our finding, we stored a flat phase Gaussian beam with
a dark center. Contrary to the optical vortex, which stays stable for over 100
microseconds, the dark center in the retrieved flat-phased image was filled
with light at storage times as small as 10 microseconds. This experiment proves
that higher electromagnetic modes can be converted into atomic coherences, and
that modes with phase singularities are robust to decoherence effects such as
diffusion. This opens the possibility to more elaborate schemes for two
dimensional information storage in atomic vapors.
| [
{
"version": "v1",
"created": "Thu, 18 Jan 2007 13:04:24 GMT"
},
{
"version": "v2",
"created": "Fri, 19 Jan 2007 09:55:50 GMT"
},
{
"version": "v3",
"created": "Fri, 19 Jan 2007 22:24:31 GMT"
},
{
"version": "v4",
"created": "Sat, 3 Feb 2007 14:11:35 GMT"
}
]
| 2007-05-25T00:00:00 | [
[
"Pugatch",
"R.",
""
],
[
"Shuker",
"M.",
""
],
[
"Firstenberg",
"O.",
""
],
[
"Ron",
"A.",
""
],
[
"Davidson",
"N.",
""
]
]
|
quant-ph/0701133 | Klaus Molmer | Kristian Rymann Hansen and Klaus Molmer | Trapping of light pulses in ensembles of stationary Lambda atoms | 10 pages, 4 figures | null | null | null | quant-ph | null | We present a detailed theoretical description of the generation of stationary
light pulses by standing wave electromagnetically induced transparency in media
comprised of stationary atoms. We show that, contrary to thermal gas media, the
achievable storage times are limited only by the ground state dephasing rate of
the atoms, making such media ideally suited for nonlinear optical interactions
between stored pulses. Furthermore, we find significant quantitative and
qualitative differences between the two types of media, which are important for
quantum information processing schemes involving stationary light pulses.
| [
{
"version": "v1",
"created": "Thu, 18 Jan 2007 16:06:53 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Hansen",
"Kristian Rymann",
""
],
[
"Molmer",
"Klaus",
""
]
]
|
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