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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/0612163 | Johan Wulleman | Johan Wulleman | Uncoupling Which-Way Information from Interference: A Novel Interference
Experiment using a Super-Focused Laser Beam | 36 pages, 4 figures | J. Wulleman, Concepts of Physics 3 (2006) 211-261, available from
http://merlin.fic.uni.lodz.pl/concepts/index.htm | null | null | quant-ph | null | The generally accepted view in quantum theory is that information about which
way the quantum system traveled and interference visibility are complementary.
In all which-way experiments, however, an intervention takes place in the
interference process in order to determine which way the quantum system took.
This intervention can imply the tagging of a which-way marker to a quantum
system or, for instance, blocking off one of the paths in a Mach-Zehnder
interferometer so that one indirectly knows that the quantum system took the
other (open) path. It is, however, this intervention that destroys the
interference. In this paper a novel two-slit which-way interference experiment
will be discussed and proposed for implementation that provides maximum
which-way information without intervening in the interference process so that
simultaneously maximum interference visibility remains preserved. This, in
fact, implies an uncoupling of which-way information from interference and
consequently also entails violating the duality relation P^2+V^2<1. Basically,
the purpose of the proposed experiment and of this paper is to scrutinize this
duality relation. The experiment makes use of a super-focused laser beam that
is launched into only one of the two slits of the two-slit interference
experiment.
| [
{
"version": "v1",
"created": "Tue, 19 Dec 2006 12:59:07 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Wulleman",
"Johan",
""
]
]
|
quant-ph/0612164 | Erik Sjoqvist | David Kult, Johan {\AA}berg, Erik Sj\"oqvist | Non-Abelian generalization of off-diagonal geometric phases | Additional material, journal reference added | Europhys. Lett. 78, 60004 (2007) | 10.1209/0295-5075/78/60004 | null | quant-ph | null | If a quantum system evolves in a noncyclic fashion the corresponding
geometric phase or holonomy may not be fully defined. Off-diagonal geometric
phases have been developed to deal with such cases. Here, we generalize these
phases to the non-Abelian case, by introducing off-diagonal holonomies that
involve evolution of more than one subspace of the underlying Hilbert space.
Physical realizations of the off-diagonal holonomies in adiabatic evolution and
interferometry are put forward.
| [
{
"version": "v1",
"created": "Tue, 19 Dec 2006 13:22:45 GMT"
},
{
"version": "v2",
"created": "Tue, 29 May 2007 11:13:51 GMT"
}
]
| 2011-11-09T00:00:00 | [
[
"Kult",
"David",
""
],
[
"Åberg",
"Johan",
""
],
[
"Sjöqvist",
"Erik",
""
]
]
|
quant-ph/0612165 | Frank Wilhelm K. | P. Rebentrost, I. Serban, T. Schulte-Herbrueggen, and F.K. Wilhelm | Optimal control of a qubit coupled to a non-Markovian environment | 5 pages, 3 figures, improved pulse shapes | Phys.Rev.Lett.102:090401,2009 | 10.1103/PhysRevLett.102.090401 | null | quant-ph cond-mat.mes-hall | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A central challenge for implementing quantum computing in the solid state is
decoupling the qubits from the intrinsic noise of the material. We investigate
the implementation of quantum gates for a paradigmatic, non-Markovian model: A
single qubit coupled to a two-level system that is exposed to a heat bath. We
systematically search for optimal pulses using a generalization of the novel
open systems Gradient Ascent Pulse Engineering (GRAPE) algorithm. We show and
explain that next to the known optimal bias point of this model, there are
optimal shapes which refocus unwanted terms in the Hamiltonian. We study the
limitations of controls set by the decoherence properties. This can lead to a
significant improvement of quantum operations in hostile environments.
| [
{
"version": "v1",
"created": "Tue, 19 Dec 2006 14:13:56 GMT"
},
{
"version": "v2",
"created": "Wed, 31 Jan 2007 22:19:03 GMT"
},
{
"version": "v3",
"created": "Wed, 10 Dec 2008 19:49:26 GMT"
}
]
| 2010-04-22T00:00:00 | [
[
"Rebentrost",
"P.",
""
],
[
"Serban",
"I.",
""
],
[
"Schulte-Herbrueggen",
"T.",
""
],
[
"Wilhelm",
"F. K.",
""
]
]
|
quant-ph/0612166 | Damaskinsky Evgeniy Viktorovich | Vadim V. Borzov, Eugene V. Damaskinsky | Coherent States for generalized oscillator with finite-dimensional
Hilbert space | English translation of the article published in Russian | ZNS POMI vol.335, 75-99 (2006) | null | null | quant-ph | null | The construction of oscillator-like systems connected with the given set of
orthogonal polynomials and coherent states for such systems developed by
authors is extended to the case of the systems with finite-dimensional state
space. As example we consider the generalized oscillator connected with
Krawtchouk polynomials.
| [
{
"version": "v1",
"created": "Tue, 19 Dec 2006 17:22:10 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Borzov",
"Vadim V.",
""
],
[
"Damaskinsky",
"Eugene V.",
""
]
]
|
quant-ph/0612167 | Antonio Acin | Antonio Acin, J. Ignacio Cirac and Maciej Lewenstein | Entanglement Percolation in Quantum Networks | Accepted for publication in Nature Physics. This is the original
submitted version | null | 10.1038/nphys549 | null | quant-ph | null | Quantum networks are composed of nodes which can send and receive quantum
states by exchanging photons. Their goal is to facilitate quantum communication
between any nodes, something which can be used to send secret messages in a
secure way, and to communicate more efficiently than in classical networks.
These goals can be achieved, for instance, via teleportation. Here we show that
the design of efficient quantum communication protocols in quantum networks
involves intriguing quantum phenomena, depending both on the way the nodes are
displayed, and the entanglement between them. These phenomena can be employed
to design protocols which overcome the exponential decrease of signals with the
number of nodes. We relate the problem of establishing maximally entangled
states between nodes to classical percolation in statistical mechanics, and
demonstrate that quantum phase transitions can be used to optimize the
operation of quantum networks.
| [
{
"version": "v1",
"created": "Tue, 19 Dec 2006 17:45:15 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Acin",
"Antonio",
""
],
[
"Cirac",
"J. Ignacio",
""
],
[
"Lewenstein",
"Maciej",
""
]
]
|
quant-ph/0612168 | Daniel Braun | Ludovic Arnaud and Daniel Braun | Distribution of interference in random quantum algorithms | 14 pages revtex, 11 eps figures | Phys. Rev. A 75, 062314 (2007) | 10.1103/PhysRevA.75.062314 | null | quant-ph | null | We study the amount of interference in random quantum algorithms using a
recently derived quantitative measure of interference. To this end we introduce
two random circuit ensembles composed of random sequences of quantum gates from
a universal set, mimicking quantum algorithms in the quantum circuit
representation. We show numerically that these ensembles converge to the
well--known circular unitary ensemble (CUE) for general complex quantum
algorithms, and to the Haar orthogonal ensemble (HOE) for real quantum
algorithms. We provide exact analytical formulas for the average and typical
interference in the circular ensembles, and show that for sufficiently large
numbers of qubits a random quantum algorithm uses with probability close to one
an amount of interference approximately equal to the dimension of the Hilbert
space. As a by-product, we offer a new way of efficiently constructing random
operators from the Haar measures of CUE or HOE in a high dimensional Hilbert
space using universal sets of quantum gates.
| [
{
"version": "v1",
"created": "Tue, 19 Dec 2006 19:09:48 GMT"
}
]
| 2010-06-23T00:00:00 | [
[
"Arnaud",
"Ludovic",
""
],
[
"Braun",
"Daniel",
""
]
]
|
quant-ph/0612169 | Jevon Longdell | G. H\'etet, J. J. Longdell, A. L. Alexander, P. K. Lam, M. J. Sellars | Gradient Echo Quantum Memory for Light using Two-level Atoms | 4 pages, 4 figures | null | 10.1103/PhysRevLett.100.023601 | null | quant-ph | null | We propose a quantum memory for light that is analogous to the NMR gradient
echo. Our proposal is ideally perfectly efficient and provides simplifications
to current 3-level quantum memory schemes based on controlled inhomogeneous
broadening. Our scheme does not require auxiliary light fields. Instead the
input optical pulse interacts only with two-level atoms that have linearly
increasing Stark shifts. By simply reversing the sign of the atomic Stark
shifts, the pulse is retrieved in the forward direction. We present analytical,
numerical and experimental results of this scheme. We report experimental
efficiencies of up to 15% and suggest simple realizable improvements to
significantly increase the efficiency.
| [
{
"version": "v1",
"created": "Wed, 20 Dec 2006 04:17:42 GMT"
},
{
"version": "v2",
"created": "Wed, 11 Jul 2007 02:17:27 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Hétet",
"G.",
""
],
[
"Longdell",
"J. J.",
""
],
[
"Alexander",
"A. L.",
""
],
[
"Lam",
"P. K.",
""
],
[
"Sellars",
"M. J.",
""
]
]
|
quant-ph/0612170 | Mark Wilde | Mark M. Wilde, Hari Krovi, Todd A. Brun | Coherent Communication with Continuous Quantum Variables | 4 pages, 3 figures | Physical Review A 75, 060303(R) (2007) | 10.1103/PhysRevA.75.060303 | CSI-07-07-01 | quant-ph | null | The coherent bit (cobit) channel is a resource intermediate between classical
and quantum communication. It produces coherent versions of teleportation and
superdense coding. We extend the cobit channel to continuous variables by
providing a definition of the coherent nat (conat) channel. We construct
several coherent protocols that use both a position-quadrature and a
momentum-quadrature conat channel with finite squeezing. Finally, we show that
the quality of squeezing diminishes through successive compositions of coherent
teleportation and superdense coding.
| [
{
"version": "v1",
"created": "Wed, 20 Dec 2006 07:36:41 GMT"
},
{
"version": "v2",
"created": "Mon, 18 Jun 2007 18:02:49 GMT"
}
]
| 2011-11-09T00:00:00 | [
[
"Wilde",
"Mark M.",
""
],
[
"Krovi",
"Hari",
""
],
[
"Brun",
"Todd A.",
""
]
]
|
quant-ph/0612171 | Thomas Sch\"urmann | Thomas Sch\"urmann | On the measurement probability of quantum phases | 3 pages, 1 figure, completely revised, content unchanged | null | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the probability by which quantum phase measurements of a given
precision can be done successfully. The least upper bound of this probability
is derived and the associated optimal state vectors are determined. The
probability bound represents an unique and continuous transition between
macroscopic and microscopic measurement precisions.
| [
{
"version": "v1",
"created": "Wed, 20 Dec 2006 07:21:15 GMT"
},
{
"version": "v2",
"created": "Wed, 7 Nov 2007 21:18:15 GMT"
},
{
"version": "v3",
"created": "Sat, 14 Feb 2009 17:39:50 GMT"
}
]
| 2009-02-14T00:00:00 | [
[
"Schürmann",
"Thomas",
""
]
]
|
quant-ph/0612172 | Matteo G. A. Paris | Federico Casagrande, Alfredo Lulli, Matteo G. A. Paris | Improving the entanglement transfer from continuous variable systems to
localized qubits using non Gaussian states | revised version, 11 pages, 7 figures (few of them low-res) | Phys. Rev A 75, 032336 (2007) | 10.1103/PhysRevA.75.032336 | null | quant-ph | null | We investigate the entanglement transfer from a bipartite continuous-variable
(CV) system to a pair of localized qubits assuming that each CV mode couples to
one qubit via the off-resonance Jaynes-Cummings interaction with different
interaction times for the two subsystems. First, we consider the case of the CV
system prepared in a Bell-like superposition and investigate the conditions for
maximum entanglement transfer. Then we analyze the general case of two-mode CV
states that can be represented by a Schmidt decomposition in the Fock number
basis. This class includes both Gaussian and non Gaussian CV states, as for
example twin-beam (TWB) and pair-coherent (TMC, also known as two-mode-coher
ent) states respectively. Under resonance conditions, equal interaction times
for both qubits and different initial preparations, we find that the
entanglement transfer is more efficient for TMC than for TWB states. In the
perspective of applications such as in cavity QED or with superconducting
qubits, we analyze in details the effects of off-resonance interactions
(detuning) and different interaction times for the two qubits, and discuss
conditions to preserve the entanglement transfer.
| [
{
"version": "v1",
"created": "Wed, 20 Dec 2006 07:51:52 GMT"
},
{
"version": "v2",
"created": "Fri, 12 Jan 2007 10:21:33 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Casagrande",
"Federico",
""
],
[
"Lulli",
"Alfredo",
""
],
[
"Paris",
"Matteo G. A.",
""
]
]
|
quant-ph/0612173 | Hartmut Wachter | Hartmut Wachter | Quantum kinematics on q-deformed quantum spaces I, Mathematical
Framework | null | null | null | null | quant-ph | null | The aim of these two papers (I and II) is to try to give fundamental concepts
of quantum kinematics to q-deformed quantum spaces. Paper I introduces the
relevant mathematical concepts. A short review of the basic ideas of q-deformed
analysis is given. These considerations are continued by introducing q-deformed
analogs of Fourier transformations and delta functions. Their properties are
discussed in detail. Furthermore, q-deformed versions of sesquilinear forms are
defined, their basic properties are derived, and q-analogs of the
Fourier-Plancherel identity are proved. In paper II these reasonings are
applied to wave functions on position and momentum space.
| [
{
"version": "v1",
"created": "Wed, 20 Dec 2006 09:21:27 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Wachter",
"Hartmut",
""
]
]
|
quant-ph/0612174 | Hartmut Wachter | Hartmut Wachter | Quantum kinematics on q-deformed quantum spaces II, Wave functions on
position and momentum space | 72 pages, no figures, Latex | null | null | null | quant-ph | null | The aim of Part II of this paper is to try to describe wave functions on
q-deformed versions of position and momentum space. This task is done within
the framework developed in Part I of the paper. In order to make Part II
self-contained the most important results of Part I are reviewed. Then it is
shown that q-deformed exponentials and q-deformed delta functions play the role
of momentum and position eigenfunctions, respectively. Their completeness and
orthonormality relations are derived. For both bases of eigenfunctions matrix
elements of position and momentum operators are calculated. A q-deformed
version of the spectral decomposition of multiplication operators is discussed
and q-analogs of Heaviside functions are proposed. Interpreting the results
from the point of view provided by the concept of quasipoints gives the
formalism a physical meaning. The definition of expectation values and the
calculation of probability densities are explained in detail. Finally, it is
outlined how the considerations so far carry over to antisymmetrized spaces.
| [
{
"version": "v1",
"created": "Wed, 20 Dec 2006 09:42:54 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Wachter",
"Hartmut",
""
]
]
|
quant-ph/0612175 | Arnaud Dupays | Arnaud Dupays, Bruno Lepetit, J. Alberto Beswick, Carlo Rizzo, and
Dimitar Bakalov | Hyperspherical elliptic coordinates treatment of muon transfer from
muonic hydrogen to atomic oxygen | 6 pages, 7 figures | Phys. Rev. A, 68, 062506 (2003) | 10.1103/PhysRevA.68.062506 | null | quant-ph | null | Quantum-mechanical calculations of muon transfer between muonic hydrogen and
an oxygen nuclei for $s$ waves and collision energies in the range $10^{-3} -
10^3$ eV, are presented. Close-coupling time-independent Schr\"odinger
equations, written in terms of hyperspherical elliptic coordinates were
integrated along the hyper-radius to obtain the partial and total muon-transfer
probabilities. The results show the expected Wigner-Bethe threshold behavior up
to collision energies of the order of $10^{-2}$ eV and pronounced maxima at
$10^2$ eV which can be interpreted in terms of crossings between potential
energy curves corresponding to the entrance channel state $(\mu p)_{1s} + \mO$
and two product channels which asymptotically correlate to $p +
(\mO\mu)_{n=5,6}$.
The population of the final states with different orbital angular momenta is
found to be essentially independent of energy in the range considered in this
work. This can be attributed to a strong selection rule for the conservation of
the quantum number associated to one of the elliptic hyperangles.
| [
{
"version": "v1",
"created": "Wed, 20 Dec 2006 10:34:03 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Dupays",
"Arnaud",
""
],
[
"Lepetit",
"Bruno",
""
],
[
"Beswick",
"J. Alberto",
""
],
[
"Rizzo",
"Carlo",
""
],
[
"Bakalov",
"Dimitar",
""
]
]
|
quant-ph/0612176 | Alexei Gilchrist | Casey R. Myers and Alexei Gilchrist | A photon loss tolerant Zeno CSIGN gate | null | null | 10.1103/PhysRevA.75.052339 | null | quant-ph | null | We model an optical implementation of a CSIGN gate that makes use of the
Quantum Zeno effect [1,2] in the presence of photon loss. The raw operation of
the gate is severely affected by this type of loss. However, we show that by
using the same photon loss codes that have been proposed for linear optical
quantum computation (LOQC), the performance is greatly enhanced and such gates
can outperform LOQC equivalents. The technique can be applied to other types of
nonlinearities, making the implementation of nonlinear optical gates much more
attractive.
| [
{
"version": "v1",
"created": "Wed, 20 Dec 2006 15:07:41 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Myers",
"Casey R.",
""
],
[
"Gilchrist",
"Alexei",
""
]
]
|
quant-ph/0612177 | Fabio Antonio Bovino | Fabio A. Bovino | Nonlinear Inequalities and Entropy-Concurrence Plane | null | null | 10.1007/s10773-007-9574-0 | null | quant-ph | null | Nonlinear inequalities based on the quadratic Renyi entropy for mixed
two-qubit states are characterized on the Entropy-Concurrence plane. This class
of inequalities is stronger than Clauser-Horne-Shimony-Holt (CHSH) inequalities
and, in particular, are violated "in toto" by the set of Type I
Maximally-Entangled-Mixture States (MEMS I).
| [
{
"version": "v1",
"created": "Wed, 20 Dec 2006 18:22:51 GMT"
},
{
"version": "v2",
"created": "Wed, 20 Dec 2006 22:41:04 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Bovino",
"Fabio A.",
""
]
]
|
quant-ph/0612178 | Peter Bruza | P.D. Bruza and R.J. Cole | Quantum Logic of Semantic Space: An Exploratory Investigation of Context
Effects in Practical Reasoning | 23 pages, Invited chapter | In S. Artemov, H. Barringer, A. S. d'Avila Garcez, L. C. Lamb and
J. Woods (eds) "We Will Show Them: Essays in Honour of Dov Gabbay", vol 1,
pp. 339-361, College Publications, 2005 | null | null | quant-ph | null | This article is an exploratory account of the the non-monotonic behaviour of
conceptual associations in the light of context. Computational approximations
of conceptual space are furnished by semantic space models which are emerging
from the fields of cognition and computational linguistics. Semantic space
models not only provide a cognitively motivated basis to underpin human
practical reasoning, but from a mathematical perspective, they are real-valued
Hilbert spaces. This introduces the highly speculative prospect of formalizing
aspects of human practical reasoning via quantum mechanics. This account
focuses on how to formalize context effects in relation to concepts as well as
keeping an eye on operational issues.
| [
{
"version": "v1",
"created": "Thu, 21 Dec 2006 04:01:27 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Bruza",
"P. D.",
""
],
[
"Cole",
"R. J.",
""
]
]
|
quant-ph/0612179 | Metod Saniga | Metod Saniga (ASTRINSTSAV), Michel Planat (FEMTO-ST) | Multiple Qubits as Symplectic Polar Spaces of Order Two | 2 pages, no figure | Advanced Studies in Theoretical Physics 1 (2007) 1 - 4 | null | null | quant-ph math-ph math.MP | null | It is surmised that the algebra of the Pauli operators on the Hilbert space
of N-qubits is embodied in the geometry of the symplectic polar space of rank N
and order two, W_{2N - 1}(2). The operators (discarding the identity) answer to
the points of W_{2N - 1}(2), their partitionings into maximally commuting
subsets correspond to spreads of the space, a maximally commuting subset has
its representative in a maximal totally isotropic subspace of W_{2N - 1}(2)
and, finally, "commuting" translates into "collinear" (or "perpendicular").
| [
{
"version": "v1",
"created": "Thu, 21 Dec 2006 09:56:37 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Saniga",
"Metod",
"",
"ASTRINSTSAV"
],
[
"Planat",
"Michel",
"",
"FEMTO-ST"
]
]
|
quant-ph/0612180 | Gavin K. Brennen | Gavin K. Brennen, Andrea Micheli, and Peter Zoller | Designing spin-1 lattice models using polar molecules | 24 pages, 5 figures | New Journal of Physics 9, 138 (2007). | 10.1088/1367-2630/9/5/138 | null | quant-ph cond-mat.other | null | We describe how to design a large class of always on spin-1 interactions
between polar molecules trapped in an optical lattice. The spin degrees of
freedom correspond to the hyperfine levels of a ro-vibrational ground state
molecule. Interactions are induced using a microwave field to mix ground states
in one hyperfine manifold with the spin entangled dipole-dipole coupled excited
states. Using multiple fields anistropic models in one, two, or three
dimensions, can be built with tunable spatial range. An illustrative example in
one dimension is the generalized Haldane model, which at a specific parameter
has a gapped valence bond solid ground state. The interaction strengths are
large compared to decoherence rates and should allow for probing the rich phase
structure of strongly correlated systems, including dimerized and gapped
phases.
| [
{
"version": "v1",
"created": "Thu, 21 Dec 2006 15:10:30 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Brennen",
"Gavin K.",
""
],
[
"Micheli",
"Andrea",
""
],
[
"Zoller",
"Peter",
""
]
]
|
quant-ph/0612181 | Song Wei | Wei Song, Tao Qin | Scheme for the implementation of optimal cloning of arbitrary single
particle atomic state into two photonic states | 4 pages, 2 figures | Commun.Theor.Phys. 49, 1515 (2008). | null | null | quant-ph | null | We present a feasible scheme to implement the $1 \to 2$ optimal cloning of
arbitrary single particle atomic state into two photonic states, which is
important for applications in long distance quantum communication. Our scheme
also realizes the tele-NOT gate of one atom to the other distant atom trapped
in another cavity. The scheme is based on the adiabatic passage and the
polarization measurement. It is robust against a number of practical noises
such as the violation of the Lamb-Dicke condition, spontaneous emission and
detection inefficiency.
| [
{
"version": "v1",
"created": "Thu, 21 Dec 2006 13:42:40 GMT"
},
{
"version": "v2",
"created": "Fri, 22 Dec 2006 10:15:58 GMT"
}
]
| 2008-10-24T00:00:00 | [
[
"Song",
"Wei",
""
],
[
"Qin",
"Tao",
""
]
]
|
quant-ph/0612182 | Agnes Sambale | Agnes Sambale, Stefan Yoshi Buhmann, Dirk-Gunnar Welsch,
Marin-Slodoban Tomas | Local-field correction to one- and two-atom van der Waals interactions | 9 pages, 2 figures, corrections according to erratum | Physical Review A 75 (4), 042109 (2007); Erratum: Physical Review
A 76 (4), 029905(E) (2007) | 10.1103/PhysRevA.75.042109 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Based on macroscopic quantum electrodynamics in linearly and causally
responding media, we study the local-field corrected van der Waals potentials
and forces for unpolarized ground-state atoms placed within a magnetoelectric
medium of arbitrary size and shape. We start from general expressions for the
van der Waals potentials in terms of the (classical) Green tensor of the
electromagnetic field and the atomic polarizability and incorporate the
local-field correction by means of the real-cavity model. In this context,
special emphasis is given to the decomposition of the Green tensor into a
medium part multiplied by a global local-field correction factor and, in the
single-atom case, a part that only depends on the cavity characteristics. The
result is used to derive general formulas for the local-field corrected van der
Waals potentials and forces. As an application, we calculate the van der Waals
potential between two ground-state atoms placed within magnetoelectric bulk
material.
| [
{
"version": "v1",
"created": "Thu, 21 Dec 2006 13:53:49 GMT"
},
{
"version": "v2",
"created": "Tue, 12 Jun 2007 12:59:34 GMT"
},
{
"version": "v3",
"created": "Thu, 14 Aug 2008 08:15:07 GMT"
}
]
| 2008-08-14T00:00:00 | [
[
"Sambale",
"Agnes",
""
],
[
"Buhmann",
"Stefan Yoshi",
""
],
[
"Welsch",
"Dirk-Gunnar",
""
],
[
"Tomas",
"Marin-Slodoban",
""
]
]
|
quant-ph/0612183 | Peter Foldi | Orsolya Kalman, Peter Foldi, Mihaly G. Benedict, F. M. Peeters | Interference induced preparation of spinpolarized electrons in a
three-terminal quantum ring | null | Physica E 40 (3), 567 (2008) | 10.1016/j.physe.2007.08.014 | null | quant-ph | null | We present an exact, analytic solution of the spin dependent quantum
transport problem with spin-orbit interaction in a one-dimensional mesoscopic
ring with one input and two output leads. We demonstrate that for appropriate
parameters spatial interference in the ring leads to a behavior analogous to
that of the Stern-Gerlach apparatus: different spin polarizations can be
achieved in the two output channels from an originally totally unpolarized
incoming spin state. It is shown that this requires an appropriate interference
of states that carry oppositely directed currents. We find that spin
polarization is possible for several geometries, including the case when the
device is not symmetric with respect to the incoming lead. A clear connection
is established between the Stern-Gerlach like property of the device and the
relevant Aharonov-Casher phases in the loop geometry.
| [
{
"version": "v1",
"created": "Thu, 21 Dec 2006 16:34:30 GMT"
}
]
| 2008-01-24T00:00:00 | [
[
"Kalman",
"Orsolya",
""
],
[
"Foldi",
"Peter",
""
],
[
"Benedict",
"Mihaly G.",
""
],
[
"Peeters",
"F. M.",
""
]
]
|
quant-ph/0612184 | Dragomir Z. Djokovic | Oleg Chterental and Dragomir Z. Djokovic | Normal Forms and Tensor Ranks of Pure States of Four Qubits | 40 pages, 8 tables, 4 figures. Table 4 and the treatment of examples
in section 4 have been corrected. The paper will appear, as an invited
chapter, in the forthcoming book "Linear Algebra Research Advances" by Nova
Science Publishers, Inc. Comments are welcome | Linear Algebra Research Advances, G. D. Ling (Ed.), Chapter 4, pp.
133-167, Nova Science Publishers, New York, 2007 | null | null | quant-ph | null | We examine the SLOCC classification of the (non-normalized) pure states of
four qubits obtained by F. Verstraete et al. The rigorous proofs of their basic
results are provided and necessary corrections implemented. We use Invariant
Theory to solve the problem of equivalence of pure states under SLOCC
transformations of determinant 1 and qubit permutations. As a byproduct, we
produce a new set of generators for the invariants of the Weyl group of type
F_4. We complete the determination of the tensor ranks of 4-qubit pure states
initiated by J.-L. Brylinski. As a result we obtain a simple algorithm for
computing these ranks. We obtain also a very simple classification of pure
states of rank at most 3.
| [
{
"version": "v1",
"created": "Thu, 21 Dec 2006 17:21:11 GMT"
},
{
"version": "v2",
"created": "Mon, 7 May 2007 04:11:58 GMT"
}
]
| 2009-09-01T00:00:00 | [
[
"Chterental",
"Oleg",
""
],
[
"Djokovic",
"Dragomir Z.",
""
]
]
|
quant-ph/0612185 | Julia Kempe | Julia Kempe | Approaches to Quantum Error Correction | 29 pages, 5 figures, survey written for Poincare seminar lecture 19
Nov. 2005. Bookchapter in "Quantum Decoherence", Poincare seminar 2005,
Progress in Mathematical Physics series, Birhaeuser, p. 85--123, 2006 | null | null | null | quant-ph | null | The purpose of this little survey is to give a simple description of the main
approaches to quantum error correction and quantum fault-tolerance. Our goal is
to convey the necessary intuitions both for the problems and their solutions in
this area. After characterising quantum errors we present several
error-correction schemes and outline the elements of a full fledged
fault-tolerant computation, which works error-free even though all of its
components can be faulty. We also mention alternative approaches to
error-correction, so called error-avoiding or decoherence-free schemes.
Technical details and generalisations are kept to a minimum.
| [
{
"version": "v1",
"created": "Thu, 21 Dec 2006 17:26:26 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Kempe",
"Julia",
""
]
]
|
quant-ph/0612186 | Maarten Van den Nest | M. Van den Nest, K. Luttmer, W. D\"ur, H. J. Briegel | Graph states as ground states of many-body spin-1/2 Hamiltonians | 10 pages, 1 figure | Phys. Rev. A 77, 012301 (2008) | 10.1103/PhysRevA.77.012301 | null | quant-ph | null | We consider the problem whether graph states can be ground states of local
interaction Hamiltonians. For Hamiltonians acting on n qubits that involve at
most two-body interactions, we show that no n-qubit graph state can be the
exact, non-degenerate ground state. We determine for any graph state the
minimal d such that it is the non-degenerate ground state of a d-body
interaction Hamiltonian, while we show for d'-body Hamiltonians H with d'<d
that the resulting ground state can only be close to the graph state at the
cost of H having a small energy gap relative to the total energy. When allowing
for ancilla particles, we show how to utilize a gadget construction introduced
in the context of the k-local Hamiltonian problem, to obtain n-qubit graph
states as non-degenerate (quasi-)ground states of a two-body Hamiltonian acting
on n'>n spins.
| [
{
"version": "v1",
"created": "Thu, 21 Dec 2006 17:54:20 GMT"
}
]
| 2008-03-18T00:00:00 | [
[
"Nest",
"M. Van den",
""
],
[
"Luttmer",
"K.",
""
],
[
"Dür",
"W.",
""
],
[
"Briegel",
"H. J.",
""
]
]
|
quant-ph/0612187 | Wayne M. Itano | W. M. Itano | Perspectives on the quantum Zeno paradox | 8 pages. Proceedings of the Sudarshan Symposium, Univ. of Texas,
November 2006 | null | null | null | quant-ph | null | As of October 2006, there were approximately 535 citations to the seminal
1977 paper of Misra and Sudarshan that pointed out the quantum Zeno paradox
(more often called the quantum Zeno effect). In simple terms, the quantum Zeno
effect refers to a slowing down of the evolution of a quantum state in the
limit that the state is observed continuously. There has been much disagreement
as to how the quantum Zeno effect should be defined and as to whether it is
really a paradox, requiring new physics, or merely a consequence of "ordinary"
quantum mechanics. The experiment of Itano, Heinzen, Bollinger, and Wineland,
published in 1990, has been cited around 347 times and seems to be the one most
often called a demonstration of the quantum Zeno effect. Given that there is
disagreement as to what the quantum Zeno effect is, there naturally is
disagreement as to whether that experiment demonstrated the quantum Zeno
effect. Some differing perspectives regarding the quantum Zeno effect and what
would constitute an experimental demonstration are discussed.
| [
{
"version": "v1",
"created": "Thu, 21 Dec 2006 18:04:38 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Itano",
"W. M.",
""
]
]
|
quant-ph/0612188 | Nergis Mavalvala | T. Corbitt, Y. Chen, H. Mueller-Ebhardt, E. Innerhofer, D. Ottaway, H.
Rehbein, D. Sigg, S. Whitcomb, C. Wipf and N. Mavalvala | An all-optical trap for a gram-scale mirror | Major revision. Replacement is version that appears in Phy. Rev.
Lett. 98, 150802 (2007) | Physical Review Letters 98, 150802 (2007) | 10.1103/PhysRevLett.98.150802 | null | quant-ph | null | We report on a stable optical trap suitable for a macroscopic mirror, wherein
the dynamics of the mirror are fully dominated by radiation pressure. The
technique employs two frequency-offset laser fields to simultaneously create a
stiff optical restoring force and a viscous optical damping force. We show how
these forces may be used to optically trap a free mass without introducing
thermal noise; and we demonstrate the technique experimentally with a 1 gram
mirror. The observed optical spring has an inferred Young's modulus of 1.2 TPa,
20% stiffer than diamond. The trap is intrinsically cold and reaches an
effective temperature of 0.8 K, limited by technical noise in our apparatus.
| [
{
"version": "v1",
"created": "Thu, 21 Dec 2006 20:04:39 GMT"
},
{
"version": "v2",
"created": "Thu, 26 Jul 2007 13:29:10 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Corbitt",
"T.",
""
],
[
"Chen",
"Y.",
""
],
[
"Mueller-Ebhardt",
"H.",
""
],
[
"Innerhofer",
"E.",
""
],
[
"Ottaway",
"D.",
""
],
[
"Rehbein",
"H.",
""
],
[
"Sigg",
"D.",
""
],
[
"Whitcomb",
"S.",
""
],
[
"Wipf",
"C.",
""
],
[
"Mavalvala",
"N.",
""
]
]
|
quant-ph/0612189 | Mattias Johnsson | Mattias Johnsson, Simon Haine, Joseph Hope, Nick Robins, Cristina
Figl, Matthew Jeppesen, Julien Dugu\'e, John Close | Semiclassical limits to the linewidth of an atom laser | 9 Figures | null | 10.1103/PhysRevA.75.043618 | null | quant-ph cond-mat.other | null | We investigate the linewidth of a quasi-continuous atom laser within a
semiclassical framework. In the high flux regime, the lasing mode can exhibit a
number of undesirable features such as density fluctuations. We show that the
output therefore has a complicated structure that can be somewhat simplified
using Raman outcoupling methods and energy-momentum selection rules. In the
weak outcoupling limit, we find that the linewidth of an atom laser is
instantaneously Fourier limited, but, due to the energy `chirp' associated with
the draining of a condensate, the long-term linewidth of an atom laser is
equivalent to the chemical potential of the condensate source. We show that
correctly sweeping the outcoupling frequency can recover the Fourier-limited
linewidth.
| [
{
"version": "v1",
"created": "Fri, 22 Dec 2006 01:45:04 GMT"
}
]
| 2016-08-16T00:00:00 | [
[
"Johnsson",
"Mattias",
""
],
[
"Haine",
"Simon",
""
],
[
"Hope",
"Joseph",
""
],
[
"Robins",
"Nick",
""
],
[
"Figl",
"Cristina",
""
],
[
"Jeppesen",
"Matthew",
""
],
[
"Dugué",
"Julien",
""
],
[
"Close",
"John",
""
]
]
|
quant-ph/0612190 | Robert W. Spekkens | Robert W. Spekkens and H. M. Wiseman | Pooling quantum states obtained by indirect measurements | Corrected a mistake regarding the scope of our original result. This
version to be published in Phys. Rev. A. 6 pages, 1 figure | Phys. Rev. A 75, 042104 (2007) | 10.1103/PhysRevA.75.042104 | null | quant-ph | null | We consider the pooling of quantum states when Alice and Bob both have one
part of a tripartite system and, on the basis of measurements on their
respective parts, each infers a quantum state for the third part S. We denote
the conditioned states which Alice and Bob assign to S by alpha and beta
respectively, while the unconditioned state of S is rho. The state assigned by
an overseer, who has all the data available to Alice and Bob, is omega. The
pooler is told only alpha, beta, and rho. We show that for certain classes of
tripartite states, this information is enough for her to reconstruct omega by
the formula omega \propto alpha rho^{-1} beta. Specifically, we identify two
classes of states for which this pooling formula works: (i) all pure states for
which the rank of rho is equal to the product of the ranks of the states of
Alice's and Bob's subsystems; (ii) all mixtures of tripartite product states
that are mutually orthogonal on S.
| [
{
"version": "v1",
"created": "Fri, 22 Dec 2006 12:25:47 GMT"
},
{
"version": "v2",
"created": "Sat, 24 Feb 2007 20:57:13 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Spekkens",
"Robert W.",
""
],
[
"Wiseman",
"H. M.",
""
]
]
|
quant-ph/0612191 | Mattias Johnsson | Mattias T. Johnsson and Joseph J. Hope | Multimode quantum limits to the linewidth of an atom laser | 8 Figures | null | 10.1103/PhysRevA.75.043619 | null | quant-ph cond-mat.other | null | The linewidth of an atom laser can be limited by excitation of higher energy
modes in the source Bose-Einstein condensate, energy shifts in that condensate
due to the atomic interactions, or phase diffusion of the lasing mode due to
those interactions. The first two are effects that can be described with a
semiclassical model, and have been studied in detail for both pumped and
unpumped atom lasers. The third is a purely quantum statistical effect, and has
been studied only in zero dimensional models. We examine an unpumped atom laser
in one dimension using a quantum field theory using stochastic methods based on
the truncated Wigner approach. This allows spatial and statistical effects to
be examined simultaneously, and the linewidth limit for unpumped atom lasers is
quantified in various limits.
| [
{
"version": "v1",
"created": "Fri, 22 Dec 2006 03:21:43 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Johnsson",
"Mattias T.",
""
],
[
"Hope",
"Joseph J.",
""
]
]
|
quant-ph/0612192 | Bruno Bellomo | B. Bellomo, G. Compagno, F. Petruccione | Loss of coherence and dressing in QED | 16 pages, 4 figures | Phys. Rev. A 74, 052112 (2006) | 10.1103/PhysRevA.74.052112 | null | quant-ph | null | The dynamics of a free charged particle, initially described by a coherent
wave packet, interacting with an environment, i.e. the electromagnetic field
characterized by a temperature $T$, is studied. Using the dipole approximation
the exact expressions for the evolution of the reduced density matrix both in
momentum and configuration space and the vacuum and the thermal contribution to
decoherence, are obtained. The time behaviour of the coherence lengths in the
two representations are given. Through the analysis of the dynamic of the field
structure associated to the particle the vacuum contribution is shown to be
linked to the birth of correlations between the single momentum components of
the particle wave packet and the virtual photons of the dressing cloud.
| [
{
"version": "v1",
"created": "Fri, 22 Dec 2006 10:46:00 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Bellomo",
"B.",
""
],
[
"Compagno",
"G.",
""
],
[
"Petruccione",
"F.",
""
]
]
|
quant-ph/0612193 | Pradyumna Kumar Pathak | G S Agarwal and P K Pathak | Realization of quantum mechanical weak values of observables using
entangled photons | null | Phys. Rev. A 75, 032108 (2007) | 10.1103/PhysRevA.75.032108 | null | quant-ph | null | We present a scheme for realization of quantum mechanical weak values of
observables using entangled photons produced in parametric down conversion. We
consider the case when the signal and idler modes are respectively in a
coherent state and vacuum. We use a low efficiency detector to detect the
photons in the idler mode.This weak detection leads to a large displacement and
fluctuations in the signal field's quantum state which can be studied by
monitoring the photon number and quadrature distributions.
| [
{
"version": "v1",
"created": "Fri, 22 Dec 2006 12:07:06 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Agarwal",
"G S",
""
],
[
"Pathak",
"P K",
""
]
]
|
quant-ph/0612194 | Martin Plenio | M.E. Reuter, M.J. Hartmann and M.B. Plenio | Geometric Phases and Critical Phenomena in a Chain of Interacting Spins | 7 Figures | Proc. Roy. Soc. Lond. A 463, 1271 (2007) | 10.1098/rspa.2007.1822 | null | quant-ph | null | The geometric phase can act as a signature for critical regions of
interacting spin chains in the limit where the corresponding circuit in
parameter space is shrunk to a point and the number of spins is extended to
infinity; for finite circuit radii or finite spin chain lengths, the geometric
phase is always trivial (a multiple of 2pi). In this work, by contrast, two
related signatures of criticality are proposed which obey finite-size scaling
and which circumvent the need for assuming any unphysical limits. They are
based on the notion of the Bargmann invariant whose phase may be regarded as a
discretized version of Berry's phase. As circuits are considered which are
composed of a discrete, finite set of vertices in parameter space, they are
able to pass directly through a critical point, rather than having to
circumnavigate it. The proposed mechanism is shown to provide a diagnostic tool
for criticality in the case of a given non-solvable one-dimensional spin chain
with nearest-neighbour interactions in the presence of an external magnetic
field.
| [
{
"version": "v1",
"created": "Fri, 22 Dec 2006 18:46:40 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Reuter",
"M. E.",
""
],
[
"Hartmann",
"M. J.",
""
],
[
"Plenio",
"M. B.",
""
]
]
|
quant-ph/0612195 | Sergei Shevchenko N. | V. V. Shamshutdinova, A. S. Kiyko, S. N. Shevchenko, B. F. Samsonov,
A. N. Omelyanchouk | Dynamics of Josephson-junction qubits with exactly solvable
time-dependent bias pulses | 11 pages, 9 figures Author's translation from Russian to English | Russ. Phys. J. 51 (2008) 578-586 | null | null | quant-ph cond-mat.supr-con | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The quantum dynamics of a two-state system (qubit) can be governed by means
of external control parameters present in time-dependent bias pulses of special
forms. We consider the class of biases for which the time evolution equation
without a dissipation can be solved exactly. Concentrating for definiteness on
the flux qubit we calculate the probability of the definite direction of the
current in the loop and its time-averaged values as functions of the qubit's
control parameters both analytically and solving numerically the equation of
motion for the density matrix in the presence of relaxation and decoherence. It
is shown that there exist such time-dependent biases that the definite current
direction probability with no dissipation taken into account becomes a
monotonously growing function of time tending to a value which may exceed 1/2.
We also calculate the probability to find the system in the excited state and
show the possibility of the inverse population in a properly driven two-state
system provided the relaxation and dephasing rates are small enough.
| [
{
"version": "v1",
"created": "Fri, 22 Dec 2006 15:19:19 GMT"
},
{
"version": "v2",
"created": "Tue, 26 Dec 2006 13:34:42 GMT"
},
{
"version": "v3",
"created": "Mon, 23 Feb 2009 18:12:19 GMT"
}
]
| 2009-02-23T00:00:00 | [
[
"Shamshutdinova",
"V. V.",
""
],
[
"Kiyko",
"A. S.",
""
],
[
"Shevchenko",
"S. N.",
""
],
[
"Samsonov",
"B. F.",
""
],
[
"Omelyanchouk",
"A. N.",
""
]
]
|
quant-ph/0612196 | Kishore Kapale | Kishore T Kapale and Jonathan P Dowling | A Bootstrapping Approach for Generating Maximally Path-Entangled Photon
States | null | Phys. Rev. Lett. vol. 99, art. no. 053602 (2007) | 10.1103/PhysRevLett.99.053602 | null | quant-ph | null | We propose a bootstrapping approach to generation of maximally path-entangled
states of photons, so called ``NOON states''. Strong atom-light interaction of
cavity QED can be employed to generate NOON states with about 100 photons;
which can then be used to boost the existing experimental Kerr nonlinearities
based on quantum coherence effects to facilitate NOON generation with
arbitrarily large number of photons all within the current experimental state
of the art technology. We also offer an alternative scheme that uses an
atom-cavity dispersive interaction to obtain sufficiently high
Kerr-nonlinearity necessary for arbitrary NOON generation.
| [
{
"version": "v1",
"created": "Fri, 22 Dec 2006 20:58:59 GMT"
},
{
"version": "v2",
"created": "Tue, 18 Mar 2008 18:47:22 GMT"
}
]
| 2008-03-18T00:00:00 | [
[
"Kapale",
"Kishore T",
""
],
[
"Dowling",
"Jonathan P",
""
]
]
|
quant-ph/0612197 | Ulrik L. Andersen | Metin Sabuncu, Ulrik L. Andersen, Gerd Leuchs | Experimental Demonstration of Continuous Variable Cloning with
Phase-Conjugate Inputs | 5 pages | null | 10.1103/PhysRevLett.98.170503 | null | quant-ph | null | We report the experimental demonstration of continuous variable cloning of
phase conjugate coherent states as proposed by Cerf and Iblisdir (Phys. Rev.
Lett. 87, 247903 (2001)). In contrast to the proposal of Cerf and Iblisdir, the
cloning transformation is accomplished using only linear optical components,
homodyne detection and feedforward. Three clones are succesfully produced with
fidelities about 89%.
| [
{
"version": "v1",
"created": "Fri, 22 Dec 2006 16:29:20 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Sabuncu",
"Metin",
""
],
[
"Andersen",
"Ulrik L.",
""
],
[
"Leuchs",
"Gerd",
""
]
]
|
quant-ph/0612198 | Matteo G. A. Paris | Maria Bondani, Alessia Allevi, Guido Zambra, Matteo G. A. Paris,
Alessandra Andreoni | Sub-shot-noise photon-number correlation in mesoscopic twin-beam of
light | 5 pages, 5 (low-res) figures, to appear on PRA | Phys. Rev. A 76, 013833 (2007) | 10.1103/PhysRevA.76.013833 | null | quant-ph | null | We demonstrate sub-shot-noise photon-number correlations in a (temporal)
multimode mesoscopic ($\sim 10^3$ detected photons) twin-beam produced by
ps-pulsed spontaneous non-degenerate parametric downconversion. We have
separately detected the signal and idler distributions of photons collected in
twin coherence areas and found that the variance of the photon-count difference
goes below the shot-noise limit by 3.25 dB. The number of temporal modes
contained in the twin-beam, as well as the size of the twin coherence areas,
depends on the pump intensity. Our scheme is based on spontaneous
downconversion and thus does not suffer from limitations due to the finite gain
of the parametric process. Twin-beams are also used to demonstrate the
conditional preparation of a nonclassical (sub-Poissonian) state.
| [
{
"version": "v1",
"created": "Fri, 22 Dec 2006 17:17:19 GMT"
},
{
"version": "v2",
"created": "Wed, 6 Jun 2007 15:21:48 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Bondani",
"Maria",
""
],
[
"Allevi",
"Alessia",
""
],
[
"Zambra",
"Guido",
""
],
[
"Paris",
"Matteo G. A.",
""
],
[
"Andreoni",
"Alessandra",
""
]
]
|
quant-ph/0612199 | J\"urgen Koslowski | Pablo Arrighi, Gilles Dowek | Lineal: A linear-algebraic Lambda-calculus | The complementary note "On the critical pairs of a rewrite system for
vector spaces" is provided in the source files. Short version :
"Linear-algebraic Lambda-calculus : higher-order and confluence", Proceedings
of RTA 08, Hagenberg, July 2008. LNCS 5117, 17, (2008). Long version : LMCS | Logical Methods in Computer Science, Volume 13, Issue 1 (March 17,
2017) lmcs:3203 | 10.23638/LMCS-13(1:8)2017 | null | quant-ph cs.LO cs.PL | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide a computational definition of the notions of vector space and
bilinear functions. We use this result to introduce a minimal language
combining higher-order computation and linear algebra. This language extends
the Lambda-calculus with the possibility to make arbitrary linear combinations
of terms alpha.t + beta.u. We describe how to "execute" this language in terms
of a few rewrite rules, and justify them through the two fundamental
requirements that the language be a language of linear operators, and that it
be higher-order. We mention the perspectives of this work in the field of
quantum computation, whose circuits we show can be easily encoded in the
calculus. Finally, we prove the confluence of the entire calculus.
| [
{
"version": "v1",
"created": "Fri, 22 Dec 2006 17:25:56 GMT"
},
{
"version": "v2",
"created": "Mon, 10 Mar 2008 18:14:56 GMT"
},
{
"version": "v3",
"created": "Wed, 10 Jun 2015 15:19:44 GMT"
},
{
"version": "v4",
"created": "Mon, 13 Mar 2017 09:42:01 GMT"
},
{
"version": "v5",
"created": "Thu, 16 Mar 2017 08:32:19 GMT"
},
{
"version": "v6",
"created": "Tue, 21 Mar 2017 16:23:59 GMT"
}
]
| 2019-03-14T00:00:00 | [
[
"Arrighi",
"Pablo",
""
],
[
"Dowek",
"Gilles",
""
]
]
|
quant-ph/0612200 | Toby Jackson | A. K. Mohapatra, T. R. Jackson, C. S. Adams | Coherent optical detection of highly excited Rydberg states using
electromagnetically induced transparency | Comments removed | null | 10.1103/PhysRevLett.98.113003 | null | quant-ph | null | We observe electromagnetically induced transparency (EIT) on the 5s to 5p
transition in a room temperature rubidium vapour cell by coupling the 5p state
to a Rydberg state (ns or nd with n=26 to 124). We demonstrate that the narrow
line-width of the EIT resonance (2 MHz) allows precise measurement of the d
state fine structure splitting, and together with the sensitivity of the
Rydberg state to electric fields, we are able to detect transient electric
fields produced by the dynamics of charges within the cell. Coherent coupling
of Rydberg states via EIT could also be used for cross-phase modulation and
photon entanglement.
| [
{
"version": "v1",
"created": "Fri, 22 Dec 2006 17:40:50 GMT"
},
{
"version": "v2",
"created": "Wed, 10 Jan 2007 11:05:46 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Mohapatra",
"A. K.",
""
],
[
"Jackson",
"T. R.",
""
],
[
"Adams",
"C. S.",
""
]
]
|
quant-ph/0612201 | Daniel A. Lidar | Shubhrangshu Dasgupta and Daniel A. Lidar (USC) | Decoherence-induced geometric phase in a multilevel atomic system | 9 pages, 12 figures | J. Phys. B 40, S127 (2007) (special issue on "Dynamical Control of
Entanglement and Decoherence by Field-Matter Interactions") | 10.1088/0953-4075/40/9/S07 | null | quant-ph | null | We consider the STIRAP process in a three-level atom. Viewed as a closed
system, no geometric phase is acquired. But in the presence of spontaneous
emission and/or collisional relaxation we show numerically that a
non-vanishing, purely real, geometric phase is acquired during STIRAP, whose
magnitude grows with the decay rates. Rather than viewing this
decoherence-induced geometric phase as a nuisance, it can be considered an
example of "beneficial decoherence": the environment provides a mechanism for
the generation of geometric phases which would otherwise require an extra
experimental control knob.
| [
{
"version": "v1",
"created": "Sun, 24 Dec 2006 00:10:55 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Dasgupta",
"Shubhrangshu",
"",
"USC"
],
[
"Lidar",
"Daniel A.",
"",
"USC"
]
]
|
quant-ph/0612202 | Vladimir Strokov N. | V. Strokov | On convergence to equilibrium in strongly coupled Bogoliubov's
oscillator model | 17 pages, no figures; proof of eq.(18) added, minor changes in
Conclusion | Infinite Dimensional Analysis, Quantum Probability and Related
Topics, 2007, Vol. 10, No. 4, pp. 573-589 | null | null | quant-ph math-ph math.MP | null | We examine classical Bogoliubov's model of a particle coupled to a heat bath
which consists of infinitely many stochastic oscillators. Bogoliubov's result
suggests that, in the stochastic limit, the model exhibits convergence to
thermodynamical equilibrium. It has recently been shown that the system does
attain the equilibrium if the coupling constant is small enough. We show that
in the case of the large coupling constant the distribution function
$\rho_{S}(q,p,t)\to 0$ pointwise as $t\to\infty$. This implies that if there is
convergence to equilibrium, then the limit measure has no finite momenta.
Besides, the probability to find the particle in any finite domain of phase
space tends to zero. This is also true for domains in the coordinate space and
in the momentum space.
| [
{
"version": "v1",
"created": "Sat, 23 Dec 2006 20:53:54 GMT"
},
{
"version": "v2",
"created": "Tue, 25 Dec 2007 17:09:12 GMT"
}
]
| 2007-12-25T00:00:00 | [
[
"Strokov",
"V.",
""
]
]
|
quant-ph/0612203 | Guowen Wang | Wang Guowen | Superseded version of the WKB approximation and explanation of emergence
of classicality | LaTex2e, 7 pages, 1 figure | null | null | null | quant-ph | null | Regarding the limit hbar-->0 as the classical limit of quantum mechanics
seems to be silly because hbar is a definite constant of physics, but it was
successfully used in the derivation of the WKB approximation. A superseded
version of the WKB approximation is proposed in the classical limit alpha-->0
where alpha=m/M is the screening parameter of an object in which m is the mass
of the effective screening layer and M the total mass. This version is
applicable to not only approximate solution of Schrodinger equation of a
quantum particle but also that of a nanoparticle. Moreover, the version shows
that the quantization rules for nanoparticles can be achieved by substituting
alpha times hbar for hbar in the Bohr-Sommerfeld quantization rules of the old
quantum theory. Most importantly, the version helps clarify the essential
difference between classical and quantum realities and understand the
transition from quantum to classical mechanics as well as quantum mechanics
itself.
| [
{
"version": "v1",
"created": "Mon, 25 Dec 2006 01:56:59 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Guowen",
"Wang",
""
]
]
|
quant-ph/0612204 | Toyohiro Tsurumaru | Toyohiro Tsurumaru | Sequential Attack with Intensity Modulation on the
Differential-Phase-Shift Quantum Key Distribution Protocol | 6 pages, 2 figures | Phys. Rev. A 75, 062319 (2007) | 10.1103/PhysRevA.75.062319 | null | quant-ph | null | In this paper, we discuss the security of the differential-phase-shift
quantum key distribution (DPSQKD) protocol by introducing an improved version
of the so-called sequential attack, which was originally discussed by Waks et
al. Our attack differs from the original form of the sequential attack in that
the attacker Eve modulates not only the phases but also the amplitude in the
superposition of the single-photon states which she sends to the receiver.
Concentrating especially on the "discretized gaussian" intensity modulation, we
show that our attack is more effective than the individual attack, which had
been the best attack up to present. As a result of this, the recent experiment
with communication distance of 100km reported by Diamanti et al. turns out to
be insecure. Moreover it can be shown that in a practical experimental setup
which is commonly used today, the communication distance achievable by the
DPSQKD protocol is less than 95km.
| [
{
"version": "v1",
"created": "Mon, 25 Dec 2006 09:26:41 GMT"
}
]
| 2007-06-25T00:00:00 | [
[
"Tsurumaru",
"Toyohiro",
""
]
]
|
quant-ph/0612205 | Yi-Xin Chen | Lin Chen and Yi-Xin Chen | Mixed Qubit Cannot Be Universally Broadcast | 5 pages, Revtex | null | 10.1103/PhysRevA.75.062322 | null | quant-ph | null | We show that there does not exist any universal quantum cloning machine that
can broadcast an arbitrary mixed qubit with a constant fidelity. Based on this
result, we investigate the dependent quantum cloner in the sense that some
parameter of the input qubit $\rho_s(\theta,\omega,\lambda)$ is regarded as
constant in the fidelity. For the case of constant $\omega$, we establish the
$1\to2$ optimal symmetric dependent cloner with a fidelity 1/2. It is also
shown that the $1\to M$ optimal quantum cloning machine for pure qubits is also
optimal for mixed qubits, when $\lambda$ is the unique parameter in the
fidelity. For general $N\to M$ broadcasting of mixed qubits, the situation is
very different.
| [
{
"version": "v1",
"created": "Mon, 25 Dec 2006 07:24:32 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Chen",
"Lin",
""
],
[
"Chen",
"Yi-Xin",
""
]
]
|
quant-ph/0612206 | Zhang Zhanjun Dr. | Jun Liu and Zhan-jun Zhang | Revisiting controlled quantum secure direct communication using a
non-symmetric quantum channel with quantum superdense coding | 5 pages | null | null | null | quant-ph | null | Recently Xia and Song [Phys. Lett. A (In press)] have proposed a controlled
quantum secure direct communication (CQSDC) protocol. They claimed that in
their protocol only with the help of the controller Charlie, the receiver Alice
can successfully extract the secret message from the sender Bob. In this
letter, first we will show that within their protocol the controller Charlie's
role can be excluded due to their unreasonable design. We then revise the
Xia-Song CQSDC protocol such that its original advantages are retained and the
CQSDC can be really realized.
| [
{
"version": "v1",
"created": "Mon, 25 Dec 2006 13:14:07 GMT"
},
{
"version": "v2",
"created": "Tue, 2 Jan 2007 09:48:29 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Liu",
"Jun",
""
],
[
"Zhang",
"Zhan-jun",
""
]
]
|
quant-ph/0612207 | Vahid Karimipour | M. Asoudeh, V. Karimipour and A. Sadrolashrafi | Quantum Phase Transitions and Matrix Product States in Spin Ladders | 20 pages, 6 figures, essential changes (i.e derivation of the
Hamiltonian), Revtex | Phys. Rev. B 75, 224427 (2007) | 10.1103/PhysRevB.75.224427 | null | quant-ph cond-mat.str-el | null | We investigate quantum phase transitions in ladders of spin 1/2 particles by
engineering suitable matrix product states for these ladders. We take into
account both discrete and continuous symmetries and provide general classes of
such models. We also study the behavior of entanglement of different
neighboring sites near the transition point and show that quantum phase
transitions in these systems are accompanied by divergences in derivatives of
entanglement.
| [
{
"version": "v1",
"created": "Mon, 25 Dec 2006 14:10:07 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Mar 2007 19:49:45 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Asoudeh",
"M.",
""
],
[
"Karimipour",
"V.",
""
],
[
"Sadrolashrafi",
"A.",
""
]
]
|
quant-ph/0612208 | Mahn-Soo Choi | Taeseung Choi, Mahn-Soo Choi | Quantum Key Distribution Using Quantum Faraday Rotators | 7 pages, 7 EPS figures | J. Phys.: Condens. Matt. 20, 275242 (2008) | 10.1088/0953-8984/20/27/275242 | null | quant-ph | null | We propose a new quantum key distribution (QKD) protocol based on the fully
quantum mechanical states of the Faraday rotators. The protocol is
unconditionally secure against collective attacks for multi-photon source up to
two photons on a noisy environment. It is also robust against impersonation
attacks. The protocol may be implemented experimentally with the current
spintronics technology on semiconductors.
| [
{
"version": "v1",
"created": "Tue, 26 Dec 2006 00:29:35 GMT"
},
{
"version": "v2",
"created": "Sun, 26 Aug 2007 03:37:27 GMT"
}
]
| 2008-09-24T00:00:00 | [
[
"Choi",
"Taeseung",
""
],
[
"Choi",
"Mahn-Soo",
""
]
]
|
quant-ph/0612209 | Marc Holman | M. Holman | On Arguments for Linear Quantum Dynamics | 14 pages, no figures | null | null | null | quant-ph gr-qc | null | Two recent arguments for linear dynamics in quantum theory are critically
re-examined. Neither argument is found to be satisfactory as it stands,
although an improved version of one of the arguments can in fact be given. This
improved version turns out to be still not completely unproblematic, but it is
argued that it contains only a single actual loophole, which is identical to a
loophole that remains in experimental proofs of nonlocality of Bell-type. It is
concluded that - within the context of the standard quantum kinematical
framework and in agreement with what has been concluded by earlier authors - a
nonlinear dynamics of density operators is inconsistent with relativistic
causality. However, it is also stressed that this conclusion in itself has
little implication for the nature of dynamics at the Hilbert space level - in
particular, it does not force dynamics to be linear at this level - nor does it
continue to be valid in contexts that go beyond the standard quantum
kinematical framework. Despite their seeming triviality, these last two points
have not always been appreciated in the literature. Finally, it is also pointed
out that the argument for complete positivity, as given in conjunction with one
of the two recent arguments for linear dynamics, in fact only establishes a
condition that is weaker than complete positivity.
| [
{
"version": "v1",
"created": "Wed, 27 Dec 2006 20:53:44 GMT"
}
]
| 2011-11-18T00:00:00 | [
[
"Holman",
"M.",
""
]
]
|
quant-ph/0612210 | Umesh Vijayashanker | A. R. Usha Devi (1), R. Prabhu (1), (Department of Physics, Bangalore
University.), A. K. Rajagopal (2) (Department of Computer Science and Center
for Quantum Studies, George Mason University and Inspire Institute Inc.) | Collective multipole-like signatures of entanglement in symmetric
N-qubit systems | REVTEX, 4 pages with 1 figure; To appear in Phys. Rev. A | Phys. Rev. A 76, 012322 (2007) | 10.1103/PhysRevA.76.012322 | null | quant-ph | null | A cogent theory of collective multipole-like quantum correlations in
symmetric multiqubit states is presented by employing SO(3) irreducible
spherical tensor representation. An arbitrary bipartite division of this system
leads to a family of inequalities to detect entanglement involving averages of
these tensors expressed in terms of the total system angular momentum operator.
Implications of this theory to the quantum nature of multipole-like
correlations of all orders in the Dicke states are deduced. A selected set of
examples illustrate these collective tests. Such tests detect entanglement in
macroscopic atomic ensembles, where individual atoms are not accessible.
| [
{
"version": "v1",
"created": "Wed, 27 Dec 2006 17:05:25 GMT"
},
{
"version": "v2",
"created": "Mon, 12 Mar 2007 01:15:27 GMT"
},
{
"version": "v3",
"created": "Fri, 22 Jun 2007 17:47:28 GMT"
}
]
| 2011-11-09T00:00:00 | [
[
"Devi",
"A. R. Usha",
""
],
[
"Prabhu",
"R.",
""
],
[
"Rajagopal",
"A. K.",
""
]
]
|
quant-ph/0612211 | Christian de Ronde | Graciela Domenech and Hector Freytes | Fuzzy Propositional Logic Associated with Quantum Computational Gates | 41 pages, no figures | I. J. Th. Phys. 45 (2006) 228-261 | 10.1007/s10773-005-9019-6 | null | quant-ph | null | We apply residuated structures associated with fuzzy logic to develop certain
aspects of information processing in quantum computing from a logical
perspective. For this purpose, we introduce an axiomatic system whose natural
interpretation is the irreversible quantum Poincare structure.
| [
{
"version": "v1",
"created": "Tue, 26 Dec 2006 20:56:56 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Domenech",
"Graciela",
""
],
[
"Freytes",
"Hector",
""
]
]
|
quant-ph/0612212 | Emilio Santos Corchero | Emilio Santos | Bell inequalities for two-photon experiments testable at low detection
efficiency without assuming fair sampling | 20 pages, no figures | null | null | null | quant-ph | null | A family of local models containing two angles as hidden variables is defined
for experiments measuring polarization correlation of optical photons.
Searching for the best model of the family, that is giving predictions most
close to quantum mechanics, allows deriving Bell-type inequalities which may be
tested with relatively low detection efficiency.
| [
{
"version": "v1",
"created": "Wed, 27 Dec 2006 15:32:03 GMT"
}
]
| 2021-06-16T00:00:00 | [
[
"Santos",
"Emilio",
""
]
]
|
quant-ph/0612213 | Salomon S. Mizrahi | E.I. Duzzioni, L. Sanz, S.S. Mizrahi and M.H.Y. Moussa | Control of the geometric phase and pseudo-spin dynamics on coupled
Bose-Einstein condensates | 1 tex file and 11 figures in pdf format | null | 10.1103/PhysRevA.75.032113 | null | quant-ph | null | We describe the behavior of two coupled Bose-Einstein condensates in
time-dependent (TD) trap potentials and TD Rabi (or tunneling) frequency, using
the two-mode approach. Starting from Bloch states, we succeed to get analytical
solutions for the TD Schroedinger equation and present a detailed analysis of
the relative and geometric phases acquired by the wave function of the
condensates, as well as their population imbalance. We also establish a
connection between the geometric phases and constants of motion which
characterize the dynamic of the system. Besides analyzing the affects of
temporality on condensates that differs by hyperfine degrees of freedom
(internal Josephson effect), we also do present a brief discussion of a one
specie condensate in a double-well potential
(external Josephson effect).
| [
{
"version": "v1",
"created": "Tue, 26 Dec 2006 21:42:12 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Duzzioni",
"E. I.",
""
],
[
"Sanz",
"L.",
""
],
[
"Mizrahi",
"S. S.",
""
],
[
"Moussa",
"M. H. Y.",
""
]
]
|
quant-ph/0612214 | Lin Xia | Lin Xia, Xu Xu, Fan Yang, Wei Xiong, Juntao Li, Qianli Ma, Xiaoji
Zhou, Hong Guo and Xuzong Chen | Manipulation of the quantum state by Majorana transition in spinor
Bose-Einstein condensates | 5 pages, 5 figures | Phys. Rev. A 77, 043622 (2008) | 10.1103/PhysRevA.77.043622 | null | quant-ph cond-mat.other | null | Manipulation of the quantum state by the Majorana transition in spinor BEC
system has been realized by altering the rotation frequency of the magnetic
field's direction. This kind of manipulation method has no limitation on the
transition speed in principle and the system is well closed, which provides a
new and superior tool to manipulate quantum states. Using this methord on
pulsed atom laser, multicomponent spinor atom laser is generated. We
demonstrate that the experiment results are agreed with the theoretical
predication.
| [
{
"version": "v1",
"created": "Wed, 27 Dec 2006 07:35:06 GMT"
},
{
"version": "v2",
"created": "Wed, 11 Apr 2007 01:54:11 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Xia",
"Lin",
""
],
[
"Xu",
"Xu",
""
],
[
"Yang",
"Fan",
""
],
[
"Xiong",
"Wei",
""
],
[
"Li",
"Juntao",
""
],
[
"Ma",
"Qianli",
""
],
[
"Zhou",
"Xiaoji",
""
],
[
"Guo",
"Hong",
""
],
[
"Chen",
"Xuzong",
""
]
]
|
quant-ph/0612215 | Gian Paolo Beretta | Gian Paolo Beretta | Positive Nonlinear Dynamical Group Uniting Quantum Mechanics and
Thermodynamics | Latex 15 pages, submitted for the Proceedings of the Conference
'Particles and Fields: Classical and Quantum' held in honor of professor
George Sudarshan in Jaca, Spain, September 18-21, 2006 | null | null | null | quant-ph | null | We discuss and motivate the form of the generator of a nonlinear quantum
dynamical group 'designed' so as to accomplish a unification of quantum
mechanics (QM) and thermodynamics. We call this nonrelativistic theory Quantum
Thermodynamics (QT). Its conceptual foundations differ from those of (von
Neumann) quantum statistical mechanics (QSM) and (Jaynes) quantum information
theory (QIT), but for thermodynamic equilibrium (TE) states it reduces to the
same mathematics, and for zero entropy states it reduces to standard unitary
QM. The nonlinear dynamical group of QT is construed so that the second law
emerges as a theorem of existence and uniqueness of a stable equilibrium state
for each set of mean values of the energy and the number of constituents. It
implements two fundamental ansatzs. The first is that in addition to the
standard QM states described by idempotent density operators (zero entropy), a
strictly isolated system admits also states that must be described by
non-idempotent density operators (nonzero entropy). The second is that for such
additional states the law of causal evolution is determined by the simultaneous
action of a Schroedinger-von Neumann-type Hamiltonian generator and a nonlinear
dissipative generator which conserves the mean values of the energy and the
number of constituents, and (in forward time) drives any density operator, no
matter how far from TE, in the 'direction' of steepest entropy ascent (maximal
entropy increase). The equation of motion can be solved not only in forward
time, to describe relaxation towards TE, but also backwards in time, to
reconstruct the 'ancestral' or primordial lowest entropy state or limit cycle
from which the system originates.
| [
{
"version": "v1",
"created": "Wed, 27 Dec 2006 13:46:27 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Beretta",
"Gian Paolo",
""
]
]
|
quant-ph/0612216 | N. David Mermin | N. David Mermin | In praise of measurement | Based on talk given at the QUPON/QIPC 2005 conference in Vienna, May,
2005. 24 pages, 21 figures | Quantum Information Processing, Vol. 5, No. 4, 239-260, August,
2006 | null | null | quant-ph | null | The role of measurement in quantum computation is examined in the light of
John Bell's critique of the how the term ``measurement'' is used in quantum
mechanics. I argue that within the field of quantum computer science the
concept of measurement is precisely defined, unproblematic, amd forms the
foundation of the entire subject.
| [
{
"version": "v1",
"created": "Wed, 27 Dec 2006 21:23:50 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Mermin",
"N. David",
""
]
]
|
quant-ph/0612217 | Alexander Jurisch | Alexander Jurisch | Quantum Mechanics from the Hamilton-Jacobi Point of View | 19 pages, 7 figures | null | null | null | quant-ph | null | In this article, we develop quantum mechanics upon the framework of the
quantum mechanical Hamilton-Jacobi theory. We will show, that the Schroedinger
point of view and the Hamilton-Jacobi point of view are fully equivalent in
their description of physical systems, but differ in their descriptive manner.
As a main result, a wave function in Hamilton-Jacobi theory can be decomposed
into travelling waves in any point in space, not only asymptotically. The well
known WKB-theory will be a special result of the more general theory, we will
develop below. By the example of the linear potential and the harmonic
oscillator, we will discuss quantum mechanics from the Hamilton-Jacobi point of
view. Soft boundary value problems as the connection problem can be solved
exactely. Quantizised energies and Maslov-indices can be calculated directely
without orthonormalizing wave-functions. Also, we will focus on trajectory
themes, which, in contrast to the Schroedinger point of view, follow naturally
from the quantum mechanical action function.
| [
{
"version": "v1",
"created": "Wed, 27 Dec 2006 21:31:08 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Jurisch",
"Alexander",
""
]
]
|
quant-ph/0612218 | Mario Ziman | Mario Ziman and Vladimir Buzek | Universality and optimality of programmable quantum processors | 9 pages | Acta Phys.Hung. B 26, 277-291 (2006) | 10.1556/APH.26.2006.3-4.8 | null | quant-ph | null | We analyze and compare the optimality of approximate and probabilistic
universal programmable quantum processors. We define several characteristics
how to quantify the optimality and we study in detail performance of three
types of programmable quantum processors based on (1) the C-NOT gate, (2) the
SWAP operation, and (3) the model of the quantum information distributor - the
QID processor. We show under which conditions the measurement assisted QID
processor is optimal. We also investigate optimality of the so-called
U-processors and we also compare the optimal approximative implementation of
U(1) qubit rotations with the known probabilistic implementation as introduced
by Vidal, Masanes and Cirac [ {\em Phys. Rev. Lett.} {\bf 88}, 047905 (2002)].
| [
{
"version": "v1",
"created": "Thu, 28 Dec 2006 14:33:57 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Ziman",
"Mario",
""
],
[
"Buzek",
"Vladimir",
""
]
]
|
quant-ph/0612219 | David Daems | E. Karpov, D. Daems and N. J. Cerf | Entanglement may enhance the channel capacity in arbitrary dimensions | 12 pages, 3 figures | Open Sys. & Information Dyn. 13, 363 (2006) | 10.1007/s11080-006-9018-y | null | quant-ph | null | We consider explicitly two examples of d-dimensional quantum channels with
correlated noise and show that, in agreement with previous results on Pauli
qubit channels, there are situations where maximally entangled input states
achieve higher values of the output mutual information than product states. We
obtain a strong dependence of this effect on the nature of the noise
correlations as well as on the parity of the space dimension, and conjecture
that when entanglement gives an advantage in terms of mutual information,
maximally entangled states achieve the channel capacity.
| [
{
"version": "v1",
"created": "Thu, 28 Dec 2006 16:31:41 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Karpov",
"E.",
""
],
[
"Daems",
"D.",
""
],
[
"Cerf",
"N. J.",
""
]
]
|
quant-ph/0612220 | Alejandro Rivas | Alejandro M.F. Rivas | Semi-classical Scar functions in phase space | 19 pages, 2 figures. Submited to Journal Of Physics A | null | 10.1088/1751-8113/40/36/006 | null | quant-ph | null | We develop a semi-classical approximation for the scar function in the
Weyl-Wigner representation in the neighborhood of a classically unstable
periodic orbit of chaotic two dimensional systems. The prediction of hyperbolic
fringes, asymptotic to the stable and unstable manifolds, is verified
computationally for a (linear) cat map, after the theory is adapted to a
discrete phase space appropriate to a quantized torus. Characteristic fringe
patterns can be distinguished even for quasi-energies where the fixed point is
not Bohr-quantized. Also the patterns are highly localized in the neighborhood
of the periodic orbit and along its stable and unstable manifolds without any
long distance patterns that appears for the case of the spectral Wigner
function.
| [
{
"version": "v1",
"created": "Thu, 28 Dec 2006 18:30:35 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Rivas",
"Alejandro M. F.",
""
]
]
|
quant-ph/0612221 | Indranil Chakrabarty ic | Indranil Chakrabarty, B.S.Choudhury | Two Party Non-Local Games | Accepted in International Journal of Theoretical Physics | IJTP, Volume 47, Number 12 / December, 2008 | 10.1007/s10773-008-9748-4 | null | quant-ph | null | In this work we have introduced two party games with respective winning
conditions. One cannot win these games deterministically in the classical world
if they are not allowed to communicate at any stage of the game. Interestingly
we find out that in quantum world, these winning conditions can be achieved if
the players share an entangled state. We also introduced a game which is
impossible to win if the players are not allowed to communicate in classical
world (both probabilistically and deterministically), yet there exists a
perfect quantum strategy by following which, one can attain the winning
condition of the game.
| [
{
"version": "v1",
"created": "Thu, 28 Dec 2006 18:40:56 GMT"
},
{
"version": "v2",
"created": "Thu, 17 Apr 2008 06:03:48 GMT"
}
]
| 2008-11-19T00:00:00 | [
[
"Chakrabarty",
"Indranil",
""
],
[
"Choudhury",
"B. S.",
""
]
]
|
quant-ph/0612222 | Fernando Semi\~ao | F. L. Semi\~ao and K. Furuya | Entanglement in the dispersive interaction of trapped ions with a
quantized field | 10 pages, 5 figures, corrected typos | Phys. Rev. A 75, 042315 (2007) | 10.1103/PhysRevA.75.042315 | null | quant-ph | null | The mode-mode entanglement between trapped ions and cavity fields is
investigated in the dispersive regime. We show how a simple initial preparation
of Gaussian coherent states and a postselection may be used to generate
motional non-local mesoscopic states (NLMS) involving ions in different traps.
We also present a study of the entanglement induced by dynamical Stark-shifts
considering a cluster of N-trapped ions. In this case, all entanglement is due
to the dependence of the Stark-shifts on the ions' state of motion manifested
as a cross-Kerr interaction between each ion and the field.
| [
{
"version": "v1",
"created": "Thu, 28 Dec 2006 19:57:29 GMT"
},
{
"version": "v2",
"created": "Wed, 18 Apr 2007 00:24:54 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Semião",
"F. L.",
""
],
[
"Furuya",
"K.",
""
]
]
|
quant-ph/0612223 | Shi-Jian Gu | Wen-Ling Chan, Jun-Peng Cao, Dong Yang, and Shi-Jian Gu | Effects of environmental parameters to total, quantum and classical
correlations | 6 pages, 4 figures | J. Phys. A: Math. Theor. 40 12143 (2007). | 10.1088/1751-8113/40/40/009 | null | quant-ph | null | We quantify the total, quantum, and classical correlations with entropic
measures, and quantitatively compare these correlations in a quantum system, as
exemplified by a Heisenberg dimer which is subjected to the change of
environmental parameters: temperature and nonuniform external field. Our
results show that the quantum correlation may exceed the classical correlation
at some nonzero temperatures, though the former is rather fragile than the
later under thermal fluctuation. The effect of the external field to the
classical correlation is quite different from the quantum correlation.
| [
{
"version": "v1",
"created": "Fri, 29 Dec 2006 03:56:36 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Chan",
"Wen-Ling",
""
],
[
"Cao",
"Jun-Peng",
""
],
[
"Yang",
"Dong",
""
],
[
"Gu",
"Shi-Jian",
""
]
]
|
quant-ph/0612224 | Tulsi Dass | Tulsi Dass | Consistent Quantum-Classical Interaction and Solution of the Measurement
Problem in Quantum Mechanics | 11 pages | null | null | CMI/PHYS-2006-1 | quant-ph | null | Supmech, an algebraic scheme of mechanics integrating noncommutative
symplectic geometry and noncommutative probability, subsumes quantum and
classical mechanics and permits consistent treatment of interaction of quantum
and classical systems. Quantum measurements are treated in this framework; the
von Neumann reduction rule (generally postulated) is derived and interpreted in
physical terms.
| [
{
"version": "v1",
"created": "Fri, 29 Dec 2006 09:48:42 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Dass",
"Tulsi",
""
]
]
|
quant-ph/0612225 | Jeong San Kim | Dong Pyo Chi, Jeong Woon Choi, Jeong San Kim, Taewan Kim, and Soojoon
Lee | Bound entangled states with nonzero distillable key rate | 7 pages, 1 figure, typos corrected, accepted for publication in PRA | null | 10.1103/PhysRevA.75.032306 | null | quant-ph | null | In this paper, we present sufficient conditions for states to have positive
distillable key rate. Exploiting the conditions, we show that the bound
entangled states given by Horodecki et al. [Phys. Rev. Lett. 94, 160502 (2005),
quant-ph/0506203] have nonzero distillable key rate, and finally exhibit a new
class of bound entangled states with positive distillable key rate, but with
negative Devetak-Winter lower bound of distillable key rate for the ccq states
of their privacy squeezed versions.
| [
{
"version": "v1",
"created": "Fri, 29 Dec 2006 12:39:15 GMT"
},
{
"version": "v2",
"created": "Tue, 16 Jan 2007 03:49:12 GMT"
},
{
"version": "v3",
"created": "Wed, 17 Jan 2007 07:30:25 GMT"
},
{
"version": "v4",
"created": "Mon, 12 Feb 2007 05:53:26 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Chi",
"Dong Pyo",
""
],
[
"Choi",
"Jeong Woon",
""
],
[
"Kim",
"Jeong San",
""
],
[
"Kim",
"Taewan",
""
],
[
"Lee",
"Soojoon",
""
]
]
|
quant-ph/0612226 | Christian de Ronde | Graciela Domenech, Hector Freytes and Christian de Ronde | Scopes and Limits of Modality in Quantum Mechanics | 9 pages, no figures | Annalen der Physik 15 (2006) 853-860 | 10.1002/andp.200610217 | null | quant-ph | null | We develop an algebraic frame for the simultaneous treatment of actual and
possible properties of quantum systems. We show that, in spite of the fact that
the language is enriched with the addition of a modal operator to the
orthomodular structure, contextuality remains a central feature of quantum
systems.
| [
{
"version": "v1",
"created": "Fri, 29 Dec 2006 13:56:01 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Domenech",
"Graciela",
""
],
[
"Freytes",
"Hector",
""
],
[
"de Ronde",
"Christian",
""
]
]
|
quant-ph/0612227 | Christian de Ronde | Graciela Domenech, Hector Freytes and Christian de Ronde | A Topological Study of Contextuality and Modality in Quantum Mechanics | 10 pages, no figures, submitted to I. J. Th. Phys | International Journal of Theoretical Physics 47 (2008) 168-174 | 10.1007/s10773-007-9595-8 | null | quant-ph | null | Kochen-Specker theorem rules out the non-contextual assignment of values to
physical magnitudes. Here we enrich the usual orthomodular structure of quantum
mechanical propositions with modal operators. This enlargement allows to refer
consistently to actual and possible properties of the system. By means of a
topological argument, more precisely in terms of the existence of sections of
sheaves, we give an extended version of Kochen-Specker theorem over this new
structure. This allows us to prove that contextuality remains a central feature
even in the enriched propositional system.
| [
{
"version": "v1",
"created": "Fri, 29 Dec 2006 14:01:41 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Domenech",
"Graciela",
""
],
[
"Freytes",
"Hector",
""
],
[
"de Ronde",
"Christian",
""
]
]
|
quant-ph/0612228 | Adam Miranowicz | S. K. Ozdemir, A. Miranowicz, T. Ota, G. Yusa, N. Imoto, Y. Hirayama | Nuclear Spins in a Nanoscale Device for Quantum Information Processing | 5 pages, 4 figures | e-J. Surf. Sci. Nanotech 4, 669-673 (2006). | 10.1380/ejssnt.2006.669 | null | quant-ph | null | Coherent oscillations between any two levels from four nuclear spin states of
I=3/2 have been demonstrated in a nanometre-scale NMR semiconductor device,
where nuclear spins are all-electrically controlled. Using this device, we
discuss quantum logic operations on two fictitious qubits of the I=3/2 system,
and propose a quantum state tomography scheme based on the measurement of
longitudinal magnetization, $M_z$.
| [
{
"version": "v1",
"created": "Fri, 29 Dec 2006 17:19:36 GMT"
}
]
| 2009-08-04T00:00:00 | [
[
"Ozdemir",
"S. K.",
""
],
[
"Miranowicz",
"A.",
""
],
[
"Ota",
"T.",
""
],
[
"Yusa",
"G.",
""
],
[
"Imoto",
"N.",
""
],
[
"Hirayama",
"Y.",
""
]
]
|
quant-ph/0612229 | Viv Kendon | Olivier Maloyer (U Paris-Sud) and Viv Kendon (U Leeds) | Decoherence vs entanglement in coined quantum walks | 11 pages, 6 embedded eps figures; v2 improved layout and discussion | New J. Phys. 9 (2007) 87 | 10.1088/1367-2630/9/4/087 | null | quant-ph | null | Quantum versions of random walks on the line and cycle show a quadratic
improvement in their spreading rate and mixing times respectively. The addition
of decoherence to the quantum walk produces a more uniform distribution on the
line, and even faster mixing on the cycle by removing the need for
time-averaging to obtain a uniform distribution. We calculate numerically the
entanglement between the coin and the position of the quantum walker and show
that the optimal decoherence rates are such that all the entanglement is just
removed by the time the final measurement is made.
| [
{
"version": "v1",
"created": "Fri, 29 Dec 2006 20:39:51 GMT"
},
{
"version": "v2",
"created": "Sun, 11 Mar 2007 19:53:34 GMT"
}
]
| 2007-07-26T00:00:00 | [
[
"Maloyer",
"Olivier",
"",
"U Paris-Sud"
],
[
"Kendon",
"Viv",
"",
"U Leeds"
]
]
|
quant-ph/0701001 | Gilles Brassard | Gilles Brassard, Andre Allan Methot | Can quantum-mechanical description of physical reality be considered
incomplete? | 12 pages, no figures, dedicated to the memory of Asher Peres | International Journal of Quantum Information, Vol. 4, no. 1, pp.
45-54, 2006 | null | null | quant-ph | null | In loving memory of Asher Peres, we discuss a most important and influential
paper written in 1935 by his thesis supervisor and mentor Nathan Rosen,
together with Albert Einstein and Boris Podolsky. In that paper, the trio known
as EPR questioned the completeness of quantum mechanics. The authors argued
that the then-new theory should not be considered final because they believed
it incapable of describing physical reality. The epic battle between Einstein
and Bohr intensified following the latter's response later the same year. Three
decades elapsed before John S. Bell gave a devastating proof that the EPR
argument was fatally flawed. The modest purpose of our paper is to give a
critical analysis of the original EPR paper and point out its logical
shortcomings in a way that could have been done 70 years ago, with no need to
wait for Bell's theorem. We also present an overview of Bohr's response in the
interest of showing how it failed to address the gist of the EPR argument.
| [
{
"version": "v1",
"created": "Sat, 30 Dec 2006 01:11:43 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Brassard",
"Gilles",
""
],
[
"Methot",
"Andre Allan",
""
]
]
|
quant-ph/0701002 | Eduardo Sergio Santini | E. Sergio Santini | Can EPR correlations be driven by an effective wormhole? | Talk given at the Eleventh Marcel Grossmann Meeting, Berlin, Germany,
23-29 July 2006 | null | null | null | quant-ph gr-qc | null | We consider the two-particle wave function of an EPR 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 such a way singularities appear in the metric, opening the
possibility, following Holland, of interpreting the EPR correlations as
originated by a wormhole effective geometry, through which physical signals can
propagate.
| [
{
"version": "v1",
"created": "Sat, 30 Dec 2006 13:04:00 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Santini",
"E. Sergio",
""
]
]
|
quant-ph/0701003 | Michael Seevinck | M. Seevinck | Separable quantum states do not have stronger correlations than local
realism. A comment on quant-ph/0611126 of Z. Chen | Welcome | null | null | null | quant-ph | null | Chen (quant-ph/0611126) has recently claimed ``exponential violation of local
realism by separable states", in the sense that multi-partite separable quantum
states are supposed to give rise to correlations and fluctuations that violate
a Bell-type inequality that Chen takes to be satisfied by local realism.
However, this can not be true since all predictions (including all correlations
and fluctuations) that separable quantum states give rise to have a local
realistic description and thus satisfy all Bell-type inequalities, and this
holds for all number of parties. Since Chen claims otherwise by presenting a
new inequality, claimed to be a Bell-type one, which separable states
supposedly can violate, there must be a flaw in the argumentation. I will
expose this flaw, not merely for clarification of this issue, but perhaps even
more importantly since it re-teaches us an old lesson John Bell taught us over
40 years ago. I will argue that this lesson provides us with a new morale
especially relevant to modern research in Bell-type inequalities.
| [
{
"version": "v1",
"created": "Tue, 2 Jan 2007 13:24:15 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Seevinck",
"M.",
""
]
]
|
quant-ph/0701004 | Michael Nielsen | Mark R. Dowling and Michael A. Nielsen | The geometry of quantum computation | 23 pages | null | null | null | quant-ph | null | Determining the quantum circuit complexity of a unitary operation is closely
related to the problem of finding minimal length paths in a particular curved
geometry [Nielsen et al, Science 311, 1133-1135 (2006)]. This paper
investigates many of the basic geometric objects associated to this space,
including the Levi-Civita connection, the geodesic equation, the curvature, and
the Jacobi equation. We show that the optimal Hamiltonian evolution for
synthesis of a desired unitary necessarily obeys a simple universal geodesic
equation. As a consequence, once the initial value of the Hamiltonian is set,
subsequent changes to the Hamiltonian are completely determined by the geodesic
equation. We develop many analytic solutions to the geodesic equation, and a
set of invariants that completely determine the geodesics. We investigate the
problem of finding minimal geodesics through a desired unitary, U, and develop
a procedure which allows us to deform the (known) geodesics of a simple and
well understood metric to the geodesics of the metric of interest in quantum
computation. This deformation procedure is illustrated using some three-qubit
numerical examples. We study the computational complexity of evaluating
distances on Riemmanian manifolds, and show that no efficient classical
algorithm for this problem exists, subject to the assumption that good
pseudorandom generators exist. Finally, we develop a canonical extension
procedure for unitary operations which allows ancilla qubits to be incorporated
into the geometric approach to quantum computing.
| [
{
"version": "v1",
"created": "Sun, 31 Dec 2006 05:17:13 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Dowling",
"Mark R.",
""
],
[
"Nielsen",
"Michael A.",
""
]
]
|
quant-ph/0701005 | Michael Khasin | M. Khasin, R. Kosloff and D. Steinitz | Negativity as a distance from a separable state | 9 pages, 1 figure | Phys. Rev. A 75, 052325 (2007) | 10.1103/PhysRevA.75.052325 | null | quant-ph | null | The computable measure of the mixed-state entanglement, the negativity, is
shown to admit a clear geometrical interpretation, when applied to
Schmidt-correlated (SC) states: the negativity of a SC state equals a distance
of the state from a pertinent separable state. As a consequence, a SC state is
separable if and only if its negativity vanishes. Another remarkable
consequence is that the negativity of a SC can be estimated "at a glance" on
the density matrix. These results are generalized to mixtures of SC states,
which emerge in certain quantum-dynamical settings.
| [
{
"version": "v1",
"created": "Mon, 1 Jan 2007 15:13:05 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Khasin",
"M.",
""
],
[
"Kosloff",
"R.",
""
],
[
"Steinitz",
"D.",
""
]
]
|
quant-ph/0701006 | Thomas Curtright | Thomas Curtright and Andrzej Veitia | Quasi-hermitian Quantum Mechanics in Phase Space | Accepted by Journal of Mathematical Physics | J.Math.Phys.48:102112,2007 | 10.1063/1.2365716 | null | quant-ph hep-th math-ph math.MP | null | We investigate quasi-hermitian quantum mechanics in phase space using
standard deformation quantization methods: Groenewold star products and Wigner
transforms. We focus on imaginary Liouville theory as a representative example
where exact results are easily obtained. We emphasize spatially periodic
solutions, compute various distribution functions and phase-space metrics, and
explore the relationships between them.
| [
{
"version": "v1",
"created": "Tue, 2 Jan 2007 04:01:54 GMT"
},
{
"version": "v2",
"created": "Mon, 15 Jan 2007 03:42:46 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Curtright",
"Thomas",
""
],
[
"Veitia",
"Andrzej",
""
]
]
|
quant-ph/0701007 | Xiang-Bin Wang | Xiang-bin Wang, J. Q. You, Franco Nori | Deterministic generation of large cluster states using non-deterministic
collective measurements based on quantum Zeno effect | 4 pages, 1 figure | Phys. Rev. A 77, 062339 (2008) | 10.1103/PhysRevA.77.062339 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a method to generate large cluster states without using
conditional (e.g., CNOT, C-phase) gates. Indeed, an arbitrarily large cluster
state can be generated and expanded almost deterministically by single-qubit
rotations and a special non-deterministic collective detection. If the rotation
of each step is sufficiently small, the quantum Zeno effect will guarantee that
the state is projected into the intended subspace after each measurement, and
an almost-perfect cluster state can be produced. We also propose a possible
implementation of this approach using superconducting flux qubits.
| [
{
"version": "v1",
"created": "Tue, 2 Jan 2007 07:09:54 GMT"
},
{
"version": "v2",
"created": "Mon, 4 Aug 2008 03:20:40 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Wang",
"Xiang-bin",
""
],
[
"You",
"J. Q.",
""
],
[
"Nori",
"Franco",
""
]
]
|
quant-ph/0701008 | Ofer Firstenberg | O. Firstenberg, M. Shuker, A. Ben-Kish, D. R. Fredkin, N. Davidson, A.
Ron | Theory of Dicke narrowing in coherent population trapping | 6 pages, 2 figures; Introduction revised | Phys. Rev. A 76, 013818 (2007) | 10.1103/PhysRevA.76.013818 | null | quant-ph | null | The Doppler effect is one of the dominant broadening mechanisms in thermal
vapor spectroscopy. For two-photon transitions one would naively expect the
Doppler effect to cause a residual broadening, proportional to the wave-vector
difference. In coherent population trapping (CPT), which is a narrow-band
phenomenon, such broadening was not observed experimentally. This has been
commonly attributed to frequent velocity-changing collisions, known to narrow
Doppler-broadened one-photon absorption lines (Dicke narrowing). Here we show
theoretically that such a narrowing mechanism indeed exists for CPT resonances.
The narrowing factor is the ratio between the atom's mean free path and the
wavelength associated with the wave-vector difference of the two radiation
fields. A possible experiment to verify the theory is suggested.
| [
{
"version": "v1",
"created": "Tue, 2 Jan 2007 09:57:57 GMT"
},
{
"version": "v2",
"created": "Mon, 15 Jan 2007 15:52:22 GMT"
}
]
| 2007-08-14T00:00:00 | [
[
"Firstenberg",
"O.",
""
],
[
"Shuker",
"M.",
""
],
[
"Ben-Kish",
"A.",
""
],
[
"Fredkin",
"D. R.",
""
],
[
"Davidson",
"N.",
""
],
[
"Ron",
"A.",
""
]
]
|
quant-ph/0701009 | Artur Garc\'ia-Saez | Alessandro Ferraro, Artur Garcia-Saez and Antonio Acin | Monogamy and ground-state entanglement in highly connected systems | 7 pages, 11 figures. Considerably extended version, with new
numerical and analytical results | Phys. Rev. A 76, 052321 (2007) | 10.1103/PhysRevA.76.052321 | null | quant-ph cond-mat.other | null | We consider the ground-state entanglement in highly connected many-body
systems, consisting of harmonic oscillators and spin-1/2 systems. Varying their
degree of connectivity, we investigate the interplay between the enhancement of
entanglement, due to connections, and its frustration, due to monogamy
constraints. Remarkably, we see that in many situations the degree of
entanglement in a highly connected system is essentially of the same order as
in a low connected one. We also identify instances in which the entanglement
decreases as the degree of connectivity increases.
| [
{
"version": "v1",
"created": "Tue, 2 Jan 2007 11:49:14 GMT"
},
{
"version": "v2",
"created": "Thu, 29 Nov 2007 10:54:38 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Ferraro",
"Alessandro",
""
],
[
"Garcia-Saez",
"Artur",
""
],
[
"Acin",
"Antonio",
""
]
]
|
quant-ph/0701010 | Alex Bernardini | Alex E. Bernardini | Limitations on the principle of stationary phase when it is applied to
tunneling analysis | 17 pages, 2 figures | Phys. Rev. A74 (2006) 062111 | 10.1103/PhysRevA.74.062111 | null | quant-ph | null | Using a recently developed procedure - multiple wave packet decomposition -
here we study the phase time formulation for tunneling/reflecting particles
colliding with a potential barrier. To partially overcome the analytical
difficulties which frequently arise when the stationary phase method is
employed for deriving phase (tunneling) time expressions, we present a
theoretical exercise involving a symmetrical collision between two identical
wave packets and an one-dimensional rectangular potential barrier. Summing the
amplitudes of the reflected and transmitted waves - using a method we call
multiple peak decomposition - is shown to allow reconstruction of the scattered
wave packets in a way which allows the stationary phase principle to be
recovered.
| [
{
"version": "v1",
"created": "Tue, 2 Jan 2007 12:41:29 GMT"
}
]
| 2009-11-10T00:00:00 | [
[
"Bernardini",
"Alex E.",
""
]
]
|
quant-ph/0701011 | Daniela Dragoman | Daniela Dragoman and Mircea Dragoman | Negative Differential Resistance of Electrons in Graphene Barrier | null | null | null | null | quant-ph | null | The graphene is a native two-dimensional crystal material consisting of a
single sheet of carbon atoms. In this unique one-atom-thick material, the
electron transport is ballistic and is described by a quantum relativistic-like
Dirac equation rather than by the Schrodinger equation. As a result, a graphene
barrier behaves very differently compared to a common semiconductor barrier. We
show that a single graphene barrier acts as a switch with a very high on-off
ratio and displays a significant differential negative resistance, which
promotes graphene as a key material in nanoelectronics.
| [
{
"version": "v1",
"created": "Tue, 2 Jan 2007 14:51:31 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Dragoman",
"Daniela",
""
],
[
"Dragoman",
"Mircea",
""
]
]
|
quant-ph/0701012 | Daniela Dragoman | Daniela Dragoman and Mircea Dragoman | Metamaterials for Ballistic Electrons | null | null | 10.1063/1.2734876 | null | quant-ph | null | The paper presents a metamaterial for ballistic electrons, which consists of
a quantum barrier formed in a semiconductor with negative effective electron
mass. This barrier is the analogue of a metamaterial for electromagnetic waves
in media with negative electrical permittivity and magnetic permeability.
Besides applications similar to those of optical metamaterials, a nanosized
slab of a metamaterial for ballistic electrons, sandwiched between quantum
wells of positive effective mass materials, reveals unexpected conduction
properties, e.g. single or multiple room temperature negative differential
conductance regions at very low voltages and with considerable peak-to-valley
ratios, while the traversal time of ballistic electrons can be tuned to larger
or smaller values than in the absence of the metamaterial slab. Thus, slow and
fast electrons, analogous to slow and fast light, occur in metamaterials for
ballistic electrons.
| [
{
"version": "v1",
"created": "Tue, 2 Jan 2007 15:02:43 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Dragoman",
"Daniela",
""
],
[
"Dragoman",
"Mircea",
""
]
]
|
quant-ph/0701013 | Jenny Hide Miss | Jenny Hide, Wonmin Son, Ian Lawrie, Vlatko Vedral | Witnessing Macroscopic Entanglement in a Staggered Magnetic Field | Accepted for publication in Physical Review A, minor changes from
previous version. 5 pages, 3 figures | Phys. Rev. A 76, 022319 (2007) | 10.1103/PhysRevA.76.022319 | null | quant-ph cond-mat.stat-mech | null | We investigate macroscopic entanglement in an infinite XX spin-1/2 chain with
staggered magnetic field, B_l=B+e^{-i\pi l}b. Using single-site entropy and by
constructing an entanglement witness, we search for the existence of
entanglement when the system is at absolute zero, as well as in thermal
equilibrium. Although the role of the alternating magnetic field b is, in
general, to suppress entanglement as do B and T, we find that when T=0,
introducing b allows the existence of entanglement even when the uniform
magnetic field B is arbitrarily large. We find that the region and the amount
of entanglement in the spin chain can be enhanced by a staggered magnetic
field.
| [
{
"version": "v1",
"created": "Tue, 2 Jan 2007 16:00:35 GMT"
},
{
"version": "v2",
"created": "Tue, 19 Jun 2007 10:37:52 GMT"
}
]
| 2008-07-21T00:00:00 | [
[
"Hide",
"Jenny",
""
],
[
"Son",
"Wonmin",
""
],
[
"Lawrie",
"Ian",
""
],
[
"Vedral",
"Vlatko",
""
]
]
|
quant-ph/0701014 | Angelo Bassi Dr. | A. Bassi | Dynamical Reduction Models: present status and future developments | 12 pages. Contribution to the Proceedings of the "Third International
Workshop DICE2006", Castello di Piombino (Tuscany), September 11-15, 2006.
Minor changes made | J.Phys.Conf.Ser.67:012013,2007 | 10.1088/1742-6596/67/1/012013 | null | quant-ph | null | We review the major achievements of the dynamical reduction program, showing
why and how it provides a unified, consistent description of physical
phenomena, from the microscopic quantum domain to the macroscopic classical
one. We discuss the difficulties in generalizing the existing models in order
to comprise also relativistic quantum field theories. We point out possible
future lines of research, ranging from mathematical physics to phenomenology.
| [
{
"version": "v1",
"created": "Wed, 3 Jan 2007 14:04:55 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Feb 2007 18:04:49 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Bassi",
"A.",
""
]
]
|
quant-ph/0701015 | Amir Kalev | I. Hen and A. Kalev | Classical States and Their Quantum Correspondence | 8 pages. We have taken a different path in showing that the
classical--quantum correspondence still holds under time evolution | null | null | null | quant-ph | null | We point out a correspondence between classical and quantum states, by
showing that for every classical distribution over phase--space, one can
construct a corresponding quantum state, such that in the classical limit of
$\hbar\to 0$ the latter converges to the former with respect to all measurable
quantities.
| [
{
"version": "v1",
"created": "Wed, 3 Jan 2007 15:09:11 GMT"
},
{
"version": "v2",
"created": "Mon, 26 Feb 2007 15:43:53 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Hen",
"I.",
""
],
[
"Kalev",
"A.",
""
]
]
|
quant-ph/0701016 | Simon Kochen | John Conway and Simon Kochen | Reply to Comments of Bassi, Ghirardi, and Tumulka on the Free Will
Theorem | We sharpen our theorem by replacing axiom FIN by a weaker axiom MIN
to answer the above authors' objections | null | 10.1007/s10701-007-9173-1 | null | quant-ph | null | We show that the authors in the title have erred in claiming that our axiom
FIN is false by conflating it with Bell locality. We also argue that the
predictions of quantum mechanics, and in particular EPR, are fully Lorentz
invariant, whereas the Free Will Theorem shows that theories with a mechanism
of reduction, such as GRW, cannot be made fully invariant.
| [
{
"version": "v1",
"created": "Wed, 3 Jan 2007 19:52:16 GMT"
},
{
"version": "v2",
"created": "Mon, 2 Jul 2007 18:15:24 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Conway",
"John",
""
],
[
"Kochen",
"Simon",
""
]
]
|
quant-ph/0701017 | Robert Prevedel | Robert Prevedel, Philip Walther, Felix Tiefenbacher, Pascal B\"ohi,
Rainer Kaltenbaek, Thomas Jennewein and Anton Zeilinger | High-speed linear optics quantum computing using active feed-forward | 19 pages, 4 figures | Nature 445, 65-69 (2007) | 10.1038/nature05346 | null | quant-ph | null | As information carriers in quantum computing, photonic qubits have the
advantage of undergoing negligible decoherence. However, the absence of any
significant photon-photon interaction is problematic for the realization of
non-trivial two-qubit gates. One solution is to introduce an effective
nonlinearity by measurements resulting in probabilistic gate operations. In
one-way quantum computation, the random quantum measurement error can be
overcome by applying a feed-forward technique, such that the future measurement
basis depends on earlier measurement results. This technique is crucial for
achieving deterministic quantum computation once a cluster state (the highly
entangled multiparticle state on which one-way quantum computation is based) is
prepared. Here we realize a concatenated scheme of measurement and active
feed-forward in a one-way quantum computing experiment. We demonstrate that,
for a perfect cluster state and no photon loss, our quantum computation scheme
would operate with good fidelity and that our feed-forward components function
with very high speed and low error for detected photons. With present
technology, the individual computational step (in our case the individual
feed-forward cycle) can be operated in less than 150 ns using electro-optical
modulators. This is an important result for the future development of one-way
quantum computers, whose large-scale implementation will depend on advances in
the production and detection of the required highly entangled cluster states.
| [
{
"version": "v1",
"created": "Thu, 4 Jan 2007 17:15:19 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Prevedel",
"Robert",
""
],
[
"Walther",
"Philip",
""
],
[
"Tiefenbacher",
"Felix",
""
],
[
"Böhi",
"Pascal",
""
],
[
"Kaltenbaek",
"Rainer",
""
],
[
"Jennewein",
"Thomas",
""
],
[
"Zeilinger",
"Anton",
""
]
]
|
quant-ph/0701018 | Rui Guo | Rui Guo and Hong Guo | Control momentum entanglement with atomic spontaneously generated
coherence | 6 pages, 10 figures | null | null | null | quant-ph | null | With atomic spontaneously generated coherence (SGC), we propose a novel
scheme to coherently control the atom--photon momentum entanglement through
atomic internal coherence. A novel phenomena of ``phase entanglement in
momentum'' is proposed, and we found, under certain conditions, that
super--high degree of momentum entanglement can be produced with this scheme.
| [
{
"version": "v1",
"created": "Fri, 5 Jan 2007 07:02:55 GMT"
},
{
"version": "v2",
"created": "Wed, 28 Feb 2007 04:12:48 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Guo",
"Rui",
""
],
[
"Guo",
"Hong",
""
]
]
|
quant-ph/0701019 | Lucien Hardy | Lucien Hardy | Quantum gravity computers: On the theory of computation with indefinite
causal structure | 24 pages. For proceedings of "Quantum Reality, Relativistic
Causality, and Closing the Epistemic Circle: An International Conference in
Honour of Abner Shimony" | null | 10.1007/978-1-4020-9107-0_21 | null | quant-ph gr-qc | null | A quantum gravity computer is one for which the particular effects of quantum
gravity are relevant. In general relativity, causal structure is non-fixed. In
quantum theory non-fixed quantities are subject to quantum uncertainty. It is
therefore likely that, in a theory of quantum gravity, we will have indefinite
causal structure. This means that there will be no matter of fact as to whether
a particular interval is timelike or not. We study the implications of this for
the theory of computation. Classical and quantum computations consist in
ivolving the state of the computer through a sequence of time steps. This will,
most likely, not be possible for a quantum gravity computer because the notion
of a time step makes no sense if we have indefinite causal structure. We show
that it is possible to set up a model for computation even in the absence of
definite causal structure by using a certain framework (the causaloid
formalism) that was developed for the purpose of correlating data taken in this
type of situation. Corresponding to a physical theory is a causaloid, Lambda
(this is a mathematical object containing information about the causal
connections between different spacetime regions). A computer is given by the
pair {Lambda, S} where S is a set of gates. Working within the causaloid
formalism, we explore the question of whether universal quantum gravity
computers are possible. We also examine whether a quantum gravity computer
might be more powerful than a quantum (or classical) computer. In particular,
we ask whether indefinite causal structure can be used as a computational
resource.
| [
{
"version": "v1",
"created": "Fri, 5 Jan 2007 10:48:08 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Hardy",
"Lucien",
""
]
]
|
quant-ph/0701020 | Manabu Hagiwara | Manabu Hagiwara, Hideki Imai | Quantum Quasi-Cyclic LDPC Codes | 18 pages, 1 figures, published in proc. of ISIT 2007, (2007 IEEE
International Symposium on Information Theory) | null | 10.1109/ISIT.2007.4557323 | null | quant-ph cs.IT math-ph math.CO math.IT math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, a construction of a pair of "regular" quasi-cyclic LDPC codes
as ingredient codes for a quantum error-correcting code is proposed. That is,
we find quantum regular LDPC codes with various weight distributions.
Furthermore our proposed codes have lots of variations for length, code rate.
These codes are obtained by a descrete mathematical characterization for model
matrices of quasi-cyclic LDPC codes.
Our proposed codes achieve a bounded distance decoding (BDD) bound, or known
as VG bound, and achieve a lower bound of the code length.
| [
{
"version": "v1",
"created": "Fri, 5 Jan 2007 10:36:46 GMT"
},
{
"version": "v2",
"created": "Wed, 18 Apr 2007 07:13:49 GMT"
},
{
"version": "v3",
"created": "Thu, 13 May 2010 04:57:03 GMT"
},
{
"version": "v4",
"created": "Sat, 28 Aug 2010 11:46:17 GMT"
}
]
| 2016-11-18T00:00:00 | [
[
"Hagiwara",
"Manabu",
""
],
[
"Imai",
"Hideki",
""
]
]
|
quant-ph/0701021 | Shang-Bin Li | Shang-Bin Li, Xu-Bo Zou, Guang-Can Guo | Nonclassicality of quantum excitation of classical coherent field in
photon loss channel | 5 pages, 5 figures, RevTex4, submitted | Phys. Rev. A 75, 045801 (2007) | 10.1103/PhysRevA.75.045801 | null | quant-ph | null | We investigate the nonclassicality of photon-added coherent states in the
photon loss channel by exploring the entanglement potential and negative Wigner
distribution. The total negative probability defined by the absolute value of
the integral of the Wigner function over the negative distribution region
reduces with the increase of decay time. The total negative probability and the
entanglement potential of pure photon-added coherent states exhibit the similar
dependence on the beam intensity. The reduce of the total negative probability
is consistent with the behavior of entanglement potential for the dissipative
single-photon-added coherent state at short decay times.
| [
{
"version": "v1",
"created": "Fri, 5 Jan 2007 12:02:33 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Li",
"Shang-Bin",
""
],
[
"Zou",
"Xu-Bo",
""
],
[
"Guo",
"Guang-Can",
""
]
]
|
quant-ph/0701022 | Dan Solomon | Dan Solomon | Some new results concerning the QFT vacuum in the Heisenberg picture | 7 pages, typos corrected | Apeiron15:567,2008 | null | null | quant-ph | null | In has been recently shown [1] that in Dirac's hole theory the vacuum state
is not the minimum energy state but that there exist quantum states with less
energy than that of the vacuum state. In this paper we extend this discussion
to quantum field theory (QFT) and consider the question of whether or not the
vacuum in QFT is the state of minimum energy. It will be shown that for a
"simple" field theory, consisting of a quantized fermion field interacting with
a classical electric field in 1-1D space-time, there exist quauntum states with
less energy than that of the vacuum state.
| [
{
"version": "v1",
"created": "Fri, 5 Jan 2007 14:30:41 GMT"
},
{
"version": "v2",
"created": "Mon, 18 Feb 2008 02:05:24 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Solomon",
"Dan",
""
]
]
|
quant-ph/0701023 | Rostislav Serota | J. M. A. S. P. Wickramasinghe, B. Goodman and R. A. Serota | Quantum jumps of saturation level rigidity and anomalous oscillations of
level number variance in the semiclassical spectrum of a modified Kepler
problem | 18 pages, 3 color figures inline | null | 10.1103/PhysRevE.77.056216 | null | quant-ph cond-mat.mes-hall nlin.SI | null | We discover quantum Hall like jumps in the saturation spectral rigidity in
the semiclassical spectrum of a modified Kepler problem as a function of the
interval center. These jumps correspond to integer decreases of the radial
winding numbers in classical periodic motion. We also discover and explain
single harmonic dominated oscillations of the level number variance with the
width of the energy interval. The level number variance becomes effectively
zero for the interval widths defined by the frequency of the shortest periodic
orbit. This signifies that there are virtually no variations from sample to
sample in the number of levels on such intervals.
| [
{
"version": "v1",
"created": "Fri, 5 Jan 2007 16:53:05 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Wickramasinghe",
"J. M. A. S. P.",
""
],
[
"Goodman",
"B.",
""
],
[
"Serota",
"R. A.",
""
]
]
|
quant-ph/0701024 | Enrique Solano | C. Thiel, T. Bastin, J. Martin, E. Solano, J. von Zanthier, and G. S.
Agarwal | Quantum Imaging with Incoherent Photons | 4 pages, 3 figures, improved presentation. Accepted in Physical
Review Letters | Phys. Rev. Lett. 99, 133603 (2007) | 10.1103/PhysRevLett.99.133603 | null | quant-ph | null | We propose a technique to obtain sub-wavelength resolution in quantum imaging
with potentially 100% contrast using incoherent light. Our method requires
neither path-entangled number states nor multi-photon absorption. The scheme
makes use of N photons spontaneously emitted by N atoms and registered by N
detectors. It is shown that for coincident detection at particular detector
positions a resolution of \lambda / N can be achieved.
| [
{
"version": "v1",
"created": "Fri, 5 Jan 2007 20:21:26 GMT"
},
{
"version": "v2",
"created": "Fri, 5 Jan 2007 22:51:09 GMT"
},
{
"version": "v3",
"created": "Fri, 10 Aug 2007 17:09:18 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Thiel",
"C.",
""
],
[
"Bastin",
"T.",
""
],
[
"Martin",
"J.",
""
],
[
"Solano",
"E.",
""
],
[
"von Zanthier",
"J.",
""
],
[
"Agarwal",
"G. S.",
""
]
]
|
quant-ph/0701025 | Hiroaki Terashima | Hiroaki Terashima, Masahito Ueda | Probabilistic reversing operation with fidelity and purity gain for
macroscopic quantum superposition | 21 pages, 2 figures | Phys.Rev. A75 (2007) 052323 | 10.1103/PhysRevA.75.052323 | null | quant-ph | null | It is shown that a large class of weak disturbances on macroscopic quantum
superpositions can be canceled by a probabilistic reversing operation on the
system. We illustrate this for spin systems undergoing an Ising-type
interaction with the environment and demonstrate that both the fidelity to the
original state and the purity of the amended state can simultaneously be
increased by the reversing operation. A possible experimental scheme to
implement our scheme is discussed.
| [
{
"version": "v1",
"created": "Sat, 6 Jan 2007 12:08:46 GMT"
},
{
"version": "v2",
"created": "Sat, 7 Apr 2007 12:40:57 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Terashima",
"Hiroaki",
""
],
[
"Ueda",
"Masahito",
""
]
]
|
quant-ph/0701026 | Wesley B. Cardoso | W. B. Cardoso and N. G. de Almeida | Truncated states obtained by iteration | 10 pages, 22 figures | Chin. Phys. Lett. Vol. 25, No. 2 (2008) 517 | 10.1088/0256-307X/25/2/045 | null | quant-ph | null | Quantum states of the electromagnetic field are of considerable importance,
finding potential application in various areas of physics, as diverse as solid
state physics, quantum communication and cosmology. In this paper we introduce
the concept of truncated states obtained via iterative processes (TSI) and
study its statistical features, making an analogy with dynamical systems theory
(DST). As a specific example, we have studied TSI for the doubling and the
logistic functions, which are standard functions in studying chaos. TSI for
both the doubling and logistic functions exhibit certain similar patterns when
their statistical features are compared from the point of view of DST. A
general method to engineer TSI in the running-wave domain is employed, which
includes the errors due to the nonidealities of detectors and photocounts.
| [
{
"version": "v1",
"created": "Sat, 6 Jan 2007 14:49:45 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Cardoso",
"W. B.",
""
],
[
"de Almeida",
"N. G.",
""
]
]
|
quant-ph/0701027 | Shahriar S. Afshar | Shahriar S. Afshar | Violation of the principle of Complementarity, and its implications | 16 pages, 11 figures, SPIE conference 5866, "THE NATURE OF LIGHT:
WHAT IS A PHOTON?", August 2005 | Proc. SPIE 5866 (2005) 229-244 | 10.1117/12.638774 | null | quant-ph | null | Bohr's principle of complementarity predicts that in a welcher weg
("which-way") experiment, obtaining fully visible interference pattern should
lead to the destruction of the path knowledge. Here I report a failure for this
prediction in an optical interferometry experiment. Coherent laser light is
passed through a dual pinhole and allowed to go through a converging lens,
which forms well-resolved images of the respective pinholes, providing complete
path knowledge. A series of thin wires are then placed at previously measured
positions corresponding to the dark fringes of the interference pattern
upstream of the lens. No reduction in the resolution and total radiant flux of
either image is found in direct disagreement with the predictions of the
principle of complementarity. In this paper, a critique of the current
measurement theory is offered, and a novel nonperturbative technique for
ensemble properties is introduced. Also, another version of this experiment
without an imaging lens is suggested, and some of the implications of the
violation of complementarity for another suggested experiment to investigate
the nature of the photon and its "empty wave" is briefly discussed.
| [
{
"version": "v1",
"created": "Sun, 7 Jan 2007 01:34:35 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Afshar",
"Shahriar S.",
""
]
]
|
quant-ph/0701028 | Feng Pan | Feng Pan, Nan Ma, Xin Guan, and J. P. Draayer | First order quantum phase transitions in the XX spin chain | 5 pages and 1 figure, LaTeX. More typos corrected; more refs added | null | null | 0703-LNNU-LSU | quant-ph | null | Quantum phase transitional behavior of a finite periodic XX spin-1/2 chain
with nearest neighbor interaction in a uniform transverse field is studied
based on the simple exact solutions. It is found that there are [N/2]
level-crossing points in the ground state, where N is the periodic number of
the system and [x] stands for the integer part of x, when the interaction
strength and magnitude of the magnetic field satisfy certain conditions. The
quantum phase transitions are of the first order due to the level-crossing. The
ground state in the thermodynamic limit will be divided into three
distinguishable quantum phases.
| [
{
"version": "v1",
"created": "Mon, 8 Jan 2007 18:47:52 GMT"
},
{
"version": "v2",
"created": "Tue, 9 Jan 2007 14:29:46 GMT"
},
{
"version": "v3",
"created": "Wed, 10 Jan 2007 23:45:52 GMT"
},
{
"version": "v4",
"created": "Sat, 3 Feb 2007 09:47:39 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Pan",
"Feng",
""
],
[
"Ma",
"Nan",
""
],
[
"Guan",
"Xin",
""
],
[
"Draayer",
"J. P.",
""
]
]
|
quant-ph/0701029 | Duanlu Zhou | D.L. Zhou and L. You | Characterizing the complete hierarchy of correlations in an $n$-party
system | 4 pages | null | null | null | quant-ph | null | A characterization of the complete correlation structure in an $n$-party
system is proposed in terms of a series of $(k,n)$ threshold classical secret
sharing protocols ($2\le k\le n$). The total correlation is shown to be the sum
of independent correlations of 2-, 3-,$...$, $n$-parties. Our result unifies
several earlier scattered works, and shines new light at the important topic of
multi-party quantum entanglement. As an application, we explicitly construct
the hierarchy of correlations in an $n$-qubit graph state.
| [
{
"version": "v1",
"created": "Sun, 7 Jan 2007 06:52:23 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Zhou",
"D. L.",
""
],
[
"You",
"L.",
""
]
]
|
quant-ph/0701030 | Daowen Qiu | Lvzhou Li, Daowen Qiu | The states of W-class as shared resources for perfect teleportation and
superdense coding | 10 pages, critical comments and suggestions are welcome | Journal of Physics A: Math. Theor. 40 (2007) 10871-10885. | 10.1088/1751-8113/40/35/010 | null | quant-ph | null | As we know, the states of triqubit systems have two important classes:
GHZ-class and W-class.
In this paper, the states of W-class are considered for teleportation and
superdense coding, and are generalized to multi-particle systems. First we
describe two transformations of the shared resources for teleportation and
superdense coding, which allow many new protocols from some known ones for
that. As an application of these transformations, we obtain a sufficient and
necessary condition for a state of W-class being suitable for perfect
teleportation and superdense coding. As another application, we find that state
$|W>_{123}={1/2}(|100>_{123}+|010>_{123}+\sqrt{2}|001>_{123})$ can be used to
transmit three classical bits by sending two qubits, which was considered to be
impossible by P. Agrawal and A. Pati [Phys. Rev. A to be published]. We
generalize the states of W-class to multi-qubit systems and multi-particle
systems with higher dimension. We propose two protocols for teleportation and
superdense coding by using W-states of multi-qubit systems that generalize the
protocols by using $|W>_{123}$ proposed by P. Agrawal and A. Pati. We obtain an
optimal way to partition some W-states of multi-qubit systems into two
subsystems, such that the entanglement between them achieves maximum value.
| [
{
"version": "v1",
"created": "Sun, 7 Jan 2007 09:22:38 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Li",
"Lvzhou",
""
],
[
"Qiu",
"Daowen",
""
]
]
|
quant-ph/0701031 | P. K. Aravind | P.K.Aravind | Variation on a theme by GHZM | 9 pages, 3 figures, PDF only | null | null | null | quant-ph | null | In the Greenberger-Horne-Zeilinger-Mermin (GHZM) proof of Bell's theorem, a
source periodically emits an entangled state of three particles whose
properties are analyzed by three distant observers and used to prove Bell's
nonlocality theorem. This paper analyzes a somewhat different gedanken
experiment involving only two observers that nevertheless makes indirect use of
the GHZ states to prove Bell's theorem. The relationship of the GHZM proof to
the present one is discussed, and it is pointed out that the latter provides an
interesting new view of the connection between the "two theorems of John Bell".
| [
{
"version": "v1",
"created": "Sun, 7 Jan 2007 18:05:11 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Aravind",
"P. K.",
""
]
]
|
quant-ph/0701032 | Dafa Li | D. Li, X. Li, H. Huang, X. Li | SLOCC invariant and semi-invariants for SLOCC classification of
four-qubits | 22 pages, no figures, 9 tables, submit the paper to a journal | Phys. Rev. A 76, 052311 (2007) | 10.1103/PhysRevA.76.052311 | null | quant-ph | null | We show there are at least 28 distinct true SLOCC entanglement classes for
four-qubits by means of SLOCC invariant and semi-invariants and derive the
number of the degenerated SLOCC classes for n-qubits.
| [
{
"version": "v1",
"created": "Mon, 8 Jan 2007 03:44:50 GMT"
},
{
"version": "v2",
"created": "Tue, 31 Jul 2007 08:06:44 GMT"
}
]
| 2012-05-08T00:00:00 | [
[
"Li",
"D.",
""
],
[
"Li",
"X.",
""
],
[
"Huang",
"H.",
""
],
[
"Li",
"X.",
""
]
]
|
quant-ph/0701033 | Jingbo Wang | J.B. Wang and B.L. Douglas | Graph identification by quantum walks | This paper has been withdrawn | null | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper has been withdrawn by the authors; replaced by arXiv:0705.2531v2
[quant-ph].
| [
{
"version": "v1",
"created": "Mon, 8 Jan 2007 08:59:51 GMT"
},
{
"version": "v2",
"created": "Mon, 22 Jan 2007 11:27:19 GMT"
},
{
"version": "v3",
"created": "Thu, 7 May 2009 18:41:14 GMT"
}
]
| 2009-05-07T00:00:00 | [
[
"Wang",
"J. B.",
""
],
[
"Douglas",
"B. L.",
""
]
]
|
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