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quant-ph/0703117 | Tzu-Chieh Wei | Tzu-Chieh Wei, Julio T. Barreiro, and Paul G. Kwiat (the University of
Illinois at Urbana-Champaign) | Hyperentangled Bell-state analysis | typos corrected, to appear in PRA, 5 pages, 2 figures, 2 tables | Phys. Rev. A 75, 060305(R) (2007) | 10.1103/PhysRevA.75.060305 | null | quant-ph | null | It is known that it is impossible to unambiguously distinguish the four Bell
states encoded in pairs of photon polarizations using only linear optics.
However, hyperentanglement, the simultaneous entanglement in more than one
degree of freedom, has been shown to assist the complete Bell analysis of the
four Bell states (given a fixed state of the other degrees of freedom). Yet
introducing other degrees of freedom also enlarges the total number of
Bell-like states. We investigate the limits for unambiguously distinguishing
these Bell-like states. In particular, when the additional degree of freedom is
qubit-like, we find that the optimal one-shot discrimination schemes are to
group the 16 states into 7 distinguishable classes, and that an unambiguous
discrimination is possible with two identical copies.
| [
{
"version": "v1",
"created": "Wed, 14 Mar 2007 04:18:54 GMT"
},
{
"version": "v2",
"created": "Thu, 21 Jun 2007 16:09:19 GMT"
}
] | 2007-06-28T00:00:00 | [
[
"Wei",
"Tzu-Chieh",
"",
"the University of\n Illinois at Urbana-Champaign"
],
[
"Barreiro",
"Julio T.",
"",
"the University of\n Illinois at Urbana-Champaign"
],
[
"Kwiat",
"Paul G.",
"",
"the University of\n Illinois at Urbana-Champaign"
]
] |
quant-ph/0703118 | Shogo Tanimura | Shogo Tanimura | Complementarity and the nature of uncertainty relations in Einstein-Bohr
recoiling slit experiment | 13 pages, 2 figures. The title is changed. Some references are added | Quanta Vol 4, No 1, 1-9 (2015) | 10.12743/quanta.v4i1.35 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A model of the Einstein-Bohr double-slit experiment is formulated in a fully
quantum theoretical setting. In this model, the state and dynamics of a movable
wall that has the double slits in it, as well as the state of a particle
incoming to the double slits, are described by quantum mechanics. Using this
model, we analyzed complementarity between exhibiting the interference pattern
and distinguishing the particle path. Comparing the Kennard-Robertson type and
the Ozawa-type uncertainty relations, we conclude that the uncertainty relation
involved in the double-slit experiment is not the Ozawa-type uncertainty
relation but the Kennard-type uncertainty relation of the position and the
momentum of the double-slit wall. A possible experiment to test the
complementarity relation is suggested. It is also argued that various phenomena
which occur at the interface of a quantum system and a classical system,
including distinguishability, interference, decoherence, quantum eraser, and
weak value, can be understood as aspects of entanglement.
| [
{
"version": "v1",
"created": "Wed, 14 Mar 2007 06:21:05 GMT"
},
{
"version": "v2",
"created": "Fri, 23 Mar 2007 03:01:02 GMT"
},
{
"version": "v3",
"created": "Wed, 11 Jun 2008 10:58:30 GMT"
},
{
"version": "v4",
"created": "Tue, 9 Jun 2015 09:56:27 GMT"
},
{
"version": "v5",
"created": "Thu, 16 Jul 2015 06:28:05 GMT"
}
] | 2015-07-17T00:00:00 | [
[
"Tanimura",
"Shogo",
""
]
] |
quant-ph/0703119 | Jan Harms | J. Harms, P. Cochrane, A. Freise | Quantum-Noise Power Spectrum of Fields with Discrete Classical
Components | 8 pages, 2 figures | null | 10.1103/PhysRevA.76.023803 | null | quant-ph gr-qc | null | We present an algorithmic approach to calculate the quantum-noise spectral
density of photocurrents generated by optical fields with arbitrary discrete
classical spectrum in coherent or squeezed states. The measurement scheme may
include an arbitrary number of demodulations of the photocurrent. Thereby, our
method is applicable to the general heterodyne detection scheme which is
implemented in many experiments. For some of these experiments, e.g. in
laser-interferometric gravitational-wave detectors, a reliable prediction of
the quantum noise of fields in coherent and squeezed states plays a decisive
role in the design phase and detector characterization. Still, our
investigation is limited in two ways. First, we only consider coherent and
squeezed states of the field and second, we demand that the photocurrent
depends linearly on the field's vacuum amplitudes which means that at least one
of the classical components is comparatively strong.
| [
{
"version": "v1",
"created": "Wed, 14 Mar 2007 09:58:49 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Harms",
"J.",
""
],
[
"Cochrane",
"P.",
""
],
[
"Freise",
"A.",
""
]
] |
quant-ph/0703120 | Michael Seevinck | Michael Seevinck, Jan-{\AA}ke Larsson | Comment on "A local realist model for correlations of the singlet
state'' (De Raedt et al., Eur. Phys. J. B 53: 139-142, 2006) | 3 pages | Eur. Phys. J. B 58, 51-53 (2007) | 10.1140/epjb/e2007-00194-3 | null | quant-ph | null | De Raedt et al. (Eur. Phys. J. B 53: 139-142, 2006) have claimed to provide a
local realist model for correlations of the singlet state in the familiar
Einstein-Podolsky-Rosen-Bohm (EPRB) experiment when time-coincidence is used to
decide which detection events should count in the analysis, and furthermore
that this suggests that it is possible to construct local realistic models that
can reproduce the quantum mechanical expectation values. In this letter we show
that these conclusions cannot be upheld since their model exploits the
so-called coincidence-time loophole. When this is properly taken into account
no startling conclusions can be drawn about local realist modelling of quantum
mechanics.
| [
{
"version": "v1",
"created": "Wed, 14 Mar 2007 09:59:25 GMT"
}
] | 2022-03-16T00:00:00 | [
[
"Seevinck",
"Michael",
""
],
[
"Larsson",
"Jan-Åke",
""
]
] |
quant-ph/0703121 | M. O. Terra Cunha | Marcelo O. Terra Cunha | The Geometry of Entanglement Sudden Death | 6 pages, 2 figures, references added, initial paragraph corrected,
sectioning adopted, some parts rewritten; accepted by New J. Phys | New Journal of Physics 9 (2007) 237 | 10.1088/1367-2630/9/7/237 | null | quant-ph | null | In open quantum systems, entanglement can vanish faster than coherence. This
phenomenon is usually called sudden death of entanglement. In this paper sudden
death of entanglement is discussed from a geometrical point of view, in the
context of two qubits. A classification of possible scenarios is presented,
with important known examples classified. Theoretical and experimental
construction of other examples is suggested as well as large dimensional and
multipartite versions of the effect.
| [
{
"version": "v1",
"created": "Wed, 14 Mar 2007 17:24:39 GMT"
},
{
"version": "v2",
"created": "Wed, 30 May 2007 14:16:07 GMT"
},
{
"version": "v3",
"created": "Mon, 25 Jun 2007 19:06:34 GMT"
}
] | 2008-02-03T00:00:00 | [
[
"Cunha",
"Marcelo O. Terra",
""
]
] |
quant-ph/0703122 | Xiongfeng Ma | Xiongfeng Ma, Chi-Hang Fred Fung, and Hoi-Kwong Lo | Quantum key distribution with entangled photon sources | comments are most welcome | Phys. Rev. A 76, 012307 (2007) | 10.1103/PhysRevA.76.012307 | null | quant-ph | null | A parametric down-conversion (PDC) source can be used as either a triggered
single photon source or an entangled photon source in quantum key distribution
(QKD). The triggering PDC QKD has already been studied in the literature. On
the other hand, a model and a post-processing protocol for the entanglement PDC
QKD are still missing. In this paper, we fill in this important gap by
proposing such a model and a post-processing protocol for the entanglement PDC
QKD. Although the PDC model is proposed to study the entanglement-based QKD, we
emphasize that our generic model may also be useful for other non-QKD
experiments involving a PDC source. Since an entangled PDC source is a basis
independent source, we apply Koashi-Preskill's security analysis to the
entanglement PDC QKD. We also investigate the entanglement PDC QKD with two-way
classical communications. We find that the recurrence scheme increases the key
rate and Gottesman-Lo protocol helps tolerate higher channel losses. By
simulating a recent 144km open-air PDC experiment, we compare three
implementations -- entanglement PDC QKD, triggering PDC QKD and coherent state
QKD. The simulation result suggests that the entanglement PDC QKD can tolerate
higher channel losses than the coherent state QKD. The coherent state QKD with
decoy states is able to achieve highest key rate in the low and medium-loss
regions. By applying Gottesman-Lo two-way post-processing protocol, the
entanglement PDC QKD can tolerate up to 70dB combined channel losses (35dB for
each channel) provided that the PDC source is placed in between Alice and Bob.
After considering statistical fluctuations, the PDC setup can tolerate up to
53dB channel losses.
| [
{
"version": "v1",
"created": "Wed, 14 Mar 2007 19:19:53 GMT"
}
] | 2007-07-12T00:00:00 | [
[
"Ma",
"Xiongfeng",
""
],
[
"Fung",
"Chi-Hang Fred",
""
],
[
"Lo",
"Hoi-Kwong",
""
]
] |
quant-ph/0703123 | Edward Hinds | Z. Moktadir, B. Darqui\'e, M. Kraft and E. A. Hinds | The effect of self-affine fractal roughness of wires on atom chips | 7 pages, 7 figures | J. Mod. Opt. 54, 2149 (2007) | 10.1080/09500340701427151 | null | quant-ph | null | Atom chips use current flowing in lithographically patterned wires to produce
microscopic magnetic traps for atoms. The density distribution of a trapped
cold atom cloud reveals disorder in the trapping potential, which results from
meandering current flow in the wire. Roughness in the edges of the wire is
usually the main cause of this behaviour. Here, we point out that the edges of
microfabricated wires normally exhibit self-affine roughness. We investigate
the consequences of this for disorder in atom traps. In particular, we consider
how closely the trap can approach the wire when there is a maximum allowable
strength of the disorder. We comment on the role of roughness in future
atom--surface interaction experiments.
| [
{
"version": "v1",
"created": "Wed, 14 Mar 2007 19:27:18 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Moktadir",
"Z.",
""
],
[
"Darquié",
"B.",
""
],
[
"Kraft",
"M.",
""
],
[
"Hinds",
"E. A.",
""
]
] |
quant-ph/0703124 | Daegene Song | Daegene Song | Immeasurability of Zero-point Energy in the Cosmological Constant
problem | 4 pages, 1 figure | null | null | null | quant-ph gr-qc | null | A huge discrepancy between the zero-point energy calculated from quantum
theory and the observed quantity in the Universe has been one of the most
illusive problems in physics. In order to examine the measurability of
zero-point energy, we construct reference frames in a given measurement using
observables. Careful and explicit construction of the reference frames
surprisingly reveals that not only is the harmonic oscillator fluctuating at
the ground level, but so is the reference frame when the measurement is
realized. The argument is then extended to examine the measurability of vacuum
energy for a quantized electromagnetic field, and it is shown that while
zero-point energy calculated from quantum theory diverges to infinity, it is
not measurable.
| [
{
"version": "v1",
"created": "Wed, 14 Mar 2007 20:05:44 GMT"
},
{
"version": "v2",
"created": "Fri, 21 Mar 2008 11:46:09 GMT"
}
] | 2008-03-21T00:00:00 | [
[
"Song",
"Daegene",
""
]
] |
quant-ph/0703125 | Timur Kamalov F. | T. F. Kamalov | Hidden Variables and Quantum Statistics Nature | 5 pages | Journal of Russian Laser Research, V. 22, N. 5, 2001, p. 475-479 | null | null | quant-ph | null | It is shown that the nature of quantum statistics can be clarified by
assuming the existence of a background of random gravitational fields and
waves, distributed isotropically in the space. This background is responsible
for correlating phases of oscillations of identical microobjects. If such a
background of random gravitational fields and waves is considered as hidden
variables then taking it into account leads to the Bell-type inequalities that
are fairly consistent with the experimental data.
| [
{
"version": "v1",
"created": "Wed, 14 Mar 2007 23:18:32 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kamalov",
"T. F.",
""
]
] |
quant-ph/0703126 | Thomas V Marcella | Thomas V Marcella | Quantum interference with slits | 12 pages, 5 figures | earlier version Eur. J. Phys. 23 (2002) 615-621 | null | null | quant-ph | null | In the experiments considered here, we measure the y-component of momentum
for a particle passing through a system of slits. The source-slit system is the
preparation apparatus that determines the state vector. Recognizing that a
system of slits is a position-measuring device allows us to ascertain that the
state vector is a position state. Then, writing the state vector in momentum
space provides a straightforward calculation for the probability amplitude and
its corresponding probability function. Interference effects, if any, are
inherent in the probability function We determine the statistical distribution
of scattered particles for four different slit systems. The results are in
agreement with the well-known interference patterns obtained in classical wave
optics.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 01:31:28 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Marcella",
"Thomas V",
""
]
] |
quant-ph/0703127 | Nirav Mehta | N. P. Mehta, B. D. Esry, C. H. Greene | Three-Body Recombination in One Dimension | 15 pages 7 figures Submitted to Physical Review A | null | 10.1103/PhysRevA.76.022711 | quant-ph/0703127 | quant-ph | null | We study the three-body problem in one dimension for both zero and finite
range interactions using the adiabatic hyperspherical approach. Particular
emphasis is placed on the threshold laws for recombination, which are derived
for all combinations of the parity and exchange symmetries. For bosons, we
provide a numerical demonstration of several universal features that appear in
the three-body system, and discuss how certain universal features in three
dimensions are different in one dimension. We show that the probability for
inelastic processes vanishes as the range of the pair-wise interaction is taken
to zero and demonstrate numerically that the recombination threshold law
manifests itself for large scattering length.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 01:53:59 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Mehta",
"N. P.",
""
],
[
"Esry",
"B. D.",
""
],
[
"Greene",
"C. H.",
""
]
] |
quant-ph/0703128 | Christian Weedbrook | Christian Weedbrook, Mile Gu, Andrew M. Lance, Thomas Symul, Ping Koy
Lam, Timothy C. Ralph | Coherent State Distinguishability in Continuous Variable Quantum
Cryptography | QCMC 2006 Proceedings Article | null | null | null | quant-ph | null | We use the probability of error as a measure of distinguishability between
two pure and two mixed symmetric coherent states in the context of continuous
variable quantum cryptography. We show that the two mixed symmetric coherent
states (in which the various components have the same real part) never give an
eavesdropper more information than two pure coherent states.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 04:32:27 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Weedbrook",
"Christian",
""
],
[
"Gu",
"Mile",
""
],
[
"Lance",
"Andrew M.",
""
],
[
"Symul",
"Thomas",
""
],
[
"Lam",
"Ping Koy",
""
],
[
"Ralph",
"Timothy C.",
""
]
] |
quant-ph/0703129 | Vlatko Vedral | Vlatko Vedral | When Do Superfluidity and Long Range Order Imply Entanglement? | 7 pages, no figures | null | null | null | quant-ph | null | We investigate tacitly assumed relationships between the concepts of
super-fluidity (-conductivity), long range order and entanglement. We prove
that the three are by no means equivalent, but that notwithstanding, some
rigorous implication can be established between them. This leads to three
different, albeit frequently related, notions of "criticality", all of which
are exemplified within the Hubbard model in the low density regime. We use
Peierls' method of twisted Hamiltonians to link the existence of entanglement
to superfluidity and (quasi)-long range order. As an application of our
formalism, we show that recent experiments with cold atoms already prove the
existence of the field theoretic, spatial entanglement in two dimensions. More
interestingly, the appearance of entanglement in these experiments seems to be
intimately related to the phase transition of the Kosterlitz Thouless type.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 05:08:30 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Vedral",
"Vlatko",
""
]
] |
quant-ph/0703130 | Sagawa Takahiro | Yuji Kurotani, Takahiro Sagawa, and Masahito Ueda | Upper bound on our knowledge about noncommuting observables for a qubit
system | 4 pages, 1 figure | Phys. Rev. A 76, 022325 (2007) | 10.1103/PhysRevA.76.022325 | null | quant-ph | null | A trade-off relation on our knowledge about two noncommuting observables of a
qubit system in simultaneous measurement is formulated. The obtained inequality
offers a quantitative information-theoretic representation of Bohr's principle
of complementarity, and can be interpreted as a trade-off relation on the
asymptotic accuracy of the maximum-likelihood estimation of the probability
distributions of observables.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 05:36:54 GMT"
},
{
"version": "v2",
"created": "Mon, 7 May 2007 10:32:48 GMT"
},
{
"version": "v3",
"created": "Fri, 3 Aug 2007 08:03:14 GMT"
},
{
"version": "v4",
"created": "Mon, 10 Sep 2007 08:51:39 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kurotani",
"Yuji",
""
],
[
"Sagawa",
"Takahiro",
""
],
[
"Ueda",
"Masahito",
""
]
] |
quant-ph/0703131 | Ramazan Sever | Sameer M. Ikhdair and Ramazan Sever | Exact solutions of the Schrodinger equation in D-dimensions for the
pseudoharmonic potential plus ring-shaped potential | 17 pages | Cent. Eur. J. Phys. 6, 685(2008) | null | null | quant-ph | null | We present analytically the exact energy bound-states solutions of the
Schrodinger equation in $D$-dimensions for a pseudoharmonic potential plus
ring-shaped potential of the form $V(r,\theta)=D_{e}(\frac{r}{%
r_{e}}-\frac{r_{e}}{r}) ^{2}+\frac{\beta \cos ^{2}\theta}{r^{2}\sin
^{2}\theta}$ by means of the conventional Nikiforov-Uvarov method. We also give
a clear recipe of how to obtain an explicit solution to the radial and angular
parts of the wave functions in terms of orthogonal polynomials. The total
energy of the system is different from the pseudoharmonic potential because of
the contribution of the angular part. The general results obtained in this work
can be reduced to the standard forms given in the literature.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 07:18:19 GMT"
}
] | 2008-07-15T00:00:00 | [
[
"Ikhdair",
"Sameer M.",
""
],
[
"Sever",
"Ramazan",
""
]
] |
quant-ph/0703132 | Koji Nagata | Koji Nagata, Sangkyung Lee, and Jaewook Ahn | Nonlocality improves Deutsch algorithm | International Journal of Quantum Information, (2008), (accepted for
publication) | null | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, [{arXiv:0810.3134}] is accepted and published. We show that the
Bell inequalities lead to a new type of linear-optical Deutsch algorithms. We
have considered a use of entangled photon pairs to determine simultaneously and
probabilistically two unknown functions. The usual Deutsch algorithm determines
one unknown function and exhibits a two to one speed up in a certain
computation on a quantum computer rather than on a classical computer. We found
that the violation of Bell locality in the Hilbert space formalism of quantum
theory predicts that the proposed {\it probabilistic} Deutsch algorithm for
computing two unknown functions exhibits at least a $2\sqrt{2}(\simeq 2.83)$ to
one speed up.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 08:34:31 GMT"
},
{
"version": "v2",
"created": "Tue, 28 Oct 2008 05:05:58 GMT"
},
{
"version": "v3",
"created": "Fri, 28 Nov 2008 06:11:29 GMT"
}
] | 2008-11-28T00:00:00 | [
[
"Nagata",
"Koji",
""
],
[
"Lee",
"Sangkyung",
""
],
[
"Ahn",
"Jaewook",
""
]
] |
quant-ph/0703133 | Akira SaiToh | Akira SaiToh, Robabeh Rahimi, and Mikio Nakahara | Nonclassical correlation in a multipartite quantum system: two measures
and evaluation | v1: 10 pages, 8 figures, IOPART, v2: introduction modified, figure 7
replaced, v3: 10 pages, 10 figures, RevTeX4, major revision with an
additional measure introduced, title changed (previous title: Non-classical
correlation in a multi-partite quantum system reconsidered), to appear in
Phys. Rev. A | Phys. Rev. A 77, 052101 (2008) | 10.1103/PhysRevA.77.052101 | null | quant-ph | null | There is a commonly recognized paradigm in which a multipartite quantum
system described by a density matrix having no product eigenbasis is considered
to possess nonclassical correlation. Supporting this paradigm, we define two
entropic measures of nonclassical correlation of a multipartite quantum system.
One is defined as the minimum uncertainty about a joint system after we collect
outcomes of particular local measurements. The other is defined by taking the
maximum over all local systems about the minimum distance between a genuine set
and a mimic set of eigenvalues of a reduced density matrix of a local system.
The latter measure is based on an artificial game to create mimic eigenvalues
of a reduced density matrix of a local system from eigenvalues of a density
matrix of a global system. Numerical computation of these measures for several
examples is performed.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 14:29:26 GMT"
},
{
"version": "v2",
"created": "Fri, 16 Mar 2007 04:47:13 GMT"
},
{
"version": "v3",
"created": "Mon, 21 Apr 2008 03:48:10 GMT"
}
] | 2008-05-02T00:00:00 | [
[
"SaiToh",
"Akira",
""
],
[
"Rahimi",
"Robabeh",
""
],
[
"Nakahara",
"Mikio",
""
]
] |
quant-ph/0703134 | Michael Seevinck | Michael Seevinck, Jos Uffink | Local commutativity versus Bell inequality violation for entangled
states and versus non-violation for separable states | V2: Most important change: we have greatly extended the discussion of
the theoretical and experimental relevance of the results. v3: Published
version | Phys. Rev. A 76, 042105 (2007) | 10.1103/PhysRevA.76.042105 | null | quant-ph | null | By introducing a quantitative `degree of commutativity' in terms of the angle
between spin-observables we present two tight quantitative trade-off relations
in the case of two qubits: First, for entangled states, between the degree of
commutativity of local observables and the maximal amount of violation of the
Bell inequality: if both local angles increase from zero to \pi/2 (i.e., the
degree of local commutativity decreases), the maximum violation of the Bell
inequality increases. Secondly, a converse trade-off relation holds for
separable states: if both local angles approach \pi/2 the maximal value
obtainable for the correlations in the Bell inequality decreases and thus the
non-violation increases. As expected, the extremes of these relations are found
in the case of anti-commuting local observables where respectively the bounds
of 2\sqrt{2} and \sqrt{2} hold for the expectation of the Bell operator. The
trade-off relations show that non-commmutativity gives ``a more than classical
result" for entangled states, whereas "a less than classical result" is
obtained for separable states. The experimental relevance of the trade-off
relation for separable states is that it provides an experimental test for two
qubit entanglement. Its advantages are twofold: in comparison to violations of
Bell inequalities it is a stronger criterion and in comparison to entanglement
witnesses it needs to make less strong assumptions about the observables
implemented in the experiment.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 10:10:22 GMT"
},
{
"version": "v2",
"created": "Sat, 7 Jul 2007 20:21:26 GMT"
},
{
"version": "v3",
"created": "Tue, 9 Oct 2007 13:15:17 GMT"
}
] | 2007-10-09T00:00:00 | [
[
"Seevinck",
"Michael",
""
],
[
"Uffink",
"Jos",
""
]
] |
quant-ph/0703135 | Harry Schmidt | Harry Schmidt, Guenter Mahler | Non Thermal Equilibrium States of Closed Bipartite Systems | RevTeX, 8 pages, 13 figures | null | 10.1103/PhysRevE.75.061111 | null | quant-ph | null | We investigate a two-level system in resonant contact with a larger
environment. The environment typically is in a canonical state with a given
temperature initially. Depending on the precise spectral structure of the
environment and the type of coupling between both systems, the smaller part may
relax to a canonical state with the same temperature as the environment (i.e.
thermal relaxation) or to some other quasi equilibrium state (non thermal
relaxation). The type of the (quasi) equilibrium state can be related to the
distribution of certain properties of the energy eigenvectors of the total
system. We examine these distributions for several abstract and concrete (spin
environment) Hamiltonian systems, the significant aspect of these distributions
can be related to the relative strength of local and interaction parts of the
Hamiltonian.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 10:17:59 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Schmidt",
"Harry",
""
],
[
"Mahler",
"Guenter",
""
]
] |
quant-ph/0703136 | Ethem Akturk | E. Akturk, O. Ozcan, R. Sever | Joint Entropy of the Harmonic Oscillator with Time Dependent Mass and
Frequency | 17 pages, 7 figures | null | null | null | quant-ph | null | Time dependent entropy of harmonic oscillator with time dependent mass and
frequency are investigated. The joint entropy so called Leipnik's entropy is
calculated by using time dependent wave function obtained by the Feynman path
integral method. It is shown that, Leipnik's entropy fluctuates with time.
However in constant mass and time dependent frequency case, entropy increases
monotonically with time.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 10:36:12 GMT"
},
{
"version": "v2",
"created": "Mon, 19 Mar 2007 12:26:27 GMT"
},
{
"version": "v3",
"created": "Sun, 23 Sep 2007 10:37:11 GMT"
}
] | 2007-09-23T00:00:00 | [
[
"Akturk",
"E.",
""
],
[
"Ozcan",
"O.",
""
],
[
"Sever",
"R.",
""
]
] |
quant-ph/0703137 | Christoph Thiel | C. Thiel, J. von Zanthier, T. Bastin, E. Solano, G. S. Agarwal | Generation of Symmetric Dicke States of Remote Qubits with Linear Optics | New version, a few modifications and a new figure, accepted in
Physical Review Letters | Phys. Rev. Lett. 99, 193602 (2007) | 10.1103/PhysRevLett.99.193602 | null | quant-ph | null | We propose a method for generating all symmetric Dicke states, either in the
long-lived internal levels of N massive particles or in the polarization
degrees of freedom of photonic qubits, using linear optical tools only. By
means of a suitable multiphoton detection technique, erasing Welcher-Weg
information, our proposed scheme allows the generation and measurement of an
important class of entangled multiqubit states.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 13:10:14 GMT"
},
{
"version": "v2",
"created": "Tue, 9 Oct 2007 17:29:43 GMT"
}
] | 2007-11-08T00:00:00 | [
[
"Thiel",
"C.",
""
],
[
"von Zanthier",
"J.",
""
],
[
"Bastin",
"T.",
""
],
[
"Solano",
"E.",
""
],
[
"Agarwal",
"G. S.",
""
]
] |
quant-ph/0703138 | Lorenz Hartmann | L. Hartmann, W. D\"ur and H.-J. Briegel | Entanglement and its dynamics in open, dissipative systems | 30 pages, 15 figures | New J. Phys. 9, 230 (2007) | 10.1088/1367-2630/9/7/230 | null | quant-ph | null | Quantum mechanical entanglement can exist in noisy open quantum systems at
high temperature. A simple mechanism, where system particles are randomly reset
to some standard initial state, can counteract the deteriorating effect of
decoherence, resulting in an entangled steady state far from thermodynamical
equilibrium. We present models for both gas-type systems and for strongly
coupled systems. We point out in which way the entanglement resulting from such
a reset mechanism is different from the entanglement that one can find in
thermal states. We develop master equations to describe the system and its
interaction with an environment, study toy models with two particles (qubits),
where the master equation can often be solved analytically, and finally examine
larger systems with possibly fluctuating particle numbers. We find that in
gas-type systems, the reset mechanism can produce an entangled steady state for
an arbitrary temperature of the environment, while this is not true in strongly
coupled systems. But even then, the temperature range where one can find
entangled steady states is typically much higher with the reset mechanism.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 14:19:25 GMT"
}
] | 2007-08-07T00:00:00 | [
[
"Hartmann",
"L.",
""
],
[
"Dür",
"W.",
""
],
[
"Briegel",
"H. -J.",
""
]
] |
quant-ph/0703139 | Galina L. Klimchitskaya | G.L.Klimchitskaya, U.Mohideen and V.M.Mostepanenko | Kramers-Kronig relations for plasma-like permittivities and the Casimir
force | 9 pages, 2 figures, 1 table; to appear in J. Phys. A: Math. Theor.
(fast track communication) | J.Phys.A40:F339-F346,2007 | 10.1088/1751-8113/40/17/F04 | null | quant-ph cond-mat.stat-mech hep-th | null | The Kramers-Kronig relations are derived for the permittivity of the usual
plasma model which neglects dissipation and of a generalized model which takes
into account the interband transitions. The generalized plasma model is shown
to be consistent with all precision experiments on the measurement of the
Casimir force.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 16:47:03 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Klimchitskaya",
"G. L.",
""
],
[
"Mohideen",
"U.",
""
],
[
"Mostepanenko",
"V. M.",
""
]
] |
quant-ph/0703140 | Halina Grushevskaya | Halina V. Grushevskaya and Leonid I. Gurskii | Effects of many-electron atom polarization in electron-hole formalism | 14 pages | null | null | null | quant-ph | null | The method has been developed to calculate effects of polarization not only
for a atomic core in a field of valent electron, but also polarization of atom
as a whole in the electron-hole formalism. A secondary quantized density matrix
for many-electron system was used to find the Green function of a quasiparticle
and its effective mass due to many-particle effects.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 17:37:26 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Grushevskaya",
"Halina V.",
""
],
[
"Gurskii",
"Leonid I.",
""
]
] |
quant-ph/0703141 | Howard N. Barnum | Howard N. Barnum | Semidefinite programming characterization and spectral adversary method
for quantum complexity with noncommuting unitary queries | Dagstuhl Seminar Proceedings 06391, "Algorithms and Complexity for
Continuous Problems," ed. S. Dahlke, K. Ritter, I. H. Sloan, J. F. Traub
(2006), available electronically at
http://drops.dagstuhl.de/portals/index.php?semnr=06391 | null | null | null | quant-ph cs.CC | null | Generalizing earlier work characterizing the quantum query complexity of
computing a function of an unknown classical ``black box'' function drawn from
some set of such black box functions, we investigate a more general quantum
query model in which the goal is to compute functions of N by N ``black box''
unitary matrices drawn from a set of such matrices, a problem with applications
to determining properties of quantum physical systems. We characterize the
existence of an algorithm for such a query problem, with given error and number
of queries, as equivalent to the feasibility of a certain set of semidefinite
programming constraints, or equivalently the infeasibility of a dual of these
constraints, which we construct. Relaxing the primal constraints to correspond
to mere pairwise near-orthogonality of the final states of a quantum computer,
conditional on black-box inputs having distinct function values, rather than
bounded-error determinability of the function value via a single measurement on
the output states, we obtain a relaxed primal program the feasibility of whose
dual still implies the nonexistence of a quantum algorithm. We use this to
obtain a generalization, to our not-necessarily-commutative setting, of the
``spectral adversary method'' for quantum query lower bounds.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 18:43:56 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Barnum",
"Howard N.",
""
]
] |
quant-ph/0703142 | Alireza Shabani | A. Shabani | Correlated errors can lead to better performance of quantum codes | 5 pages, 3 figures. Replaced by the published version. Title changed | Phys. Rev. A 77, 022323 (2008) | 10.1103/PhysRevA.77.022323 | null | quant-ph | null | A formulation for evaluating the performance of quantum error correcting
codes for a general error model is presented. In this formulation, the
correlation between errors is quantified by a Hamiltonian description of the
noise process. We classify correlated errors using the system-bath interaction:
local versus nonlocal and two-body versus many-body interactions. In
particular, we consider Calderbank-Shor-Steane codes and observe a better
performance in the presence of correlated errors depending on the timing of the
error recovery. We also find this timing to be an important factor in the
design of a coding system for achieving higher fidelities.
| [
{
"version": "v1",
"created": "Thu, 15 Mar 2007 20:30:38 GMT"
},
{
"version": "v2",
"created": "Thu, 6 Mar 2008 22:51:18 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Shabani",
"A.",
""
]
] |
quant-ph/0703143 | Kovid Goyal | Robert Raussendorf, Jim Harrington and Kovid Goyal | Topological fault-tolerance in cluster state quantum computation | 20 pages, 12 figures | New Journal of Physics 9, 199 (2007) | 10.1088/1367-2630/9/6/199 | LA-UR-07-2576 | quant-ph | null | We describe a fault-tolerant version of the one-way quantum computer using a
cluster state in three spatial dimensions. Topologically protected quantum
gates are realized by choosing appropriate boundary conditions on the cluster.
We provide equivalence transformations for these boundary conditions that can
be used to simplify fault-tolerant circuits and to derive circuit identities in
a topological manner. The spatial dimensionality of the scheme can be reduced
to two by converting one spatial axis of the cluster into time. The error
threshold is 0.75% for each source in an error model with preparation, gate,
storage and measurement errors. The operational overhead is poly-logarithmic in
the circuit size.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 18:19:20 GMT"
}
] | 2007-07-24T00:00:00 | [
[
"Raussendorf",
"Robert",
""
],
[
"Harrington",
"Jim",
""
],
[
"Goyal",
"Kovid",
""
]
] |
quant-ph/0703144 | Rosario Lo Franco | R. Lo Franco, G. Compagno, A. Messina, and A. Napoli | Generating and Revealing a Quantum Superposition of Electromagnetic
Field Binomial States in a Cavity | 4 pages, 3 figures. Title changed (published version) | Physical Review A 76, 011804(R) (2007) | 10.1103/PhysRevA.76.011804 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce the $N$-photon quantum superposition of two orthogonal
generalized binomial states of electromagnetic field. We then propose, using
resonant atom-cavity interactions, non-conditional schemes to generate and
reveal such a quantum superposition for the two-photon case in a single-mode
high-$Q$ cavity. We finally discuss the implementation of the proposed schemes.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 01:01:29 GMT"
},
{
"version": "v2",
"created": "Fri, 27 Apr 2012 15:40:03 GMT"
}
] | 2012-04-30T00:00:00 | [
[
"Franco",
"R. Lo",
""
],
[
"Compagno",
"G.",
""
],
[
"Messina",
"A.",
""
],
[
"Napoli",
"A.",
""
]
] |
quant-ph/0703145 | Katsuji Yamamoto | Hiroyuki Yamada, Katsuji Yamamoto | Efficient atomic quantum memory for photonic qubits in cavity QED | 18 pages, 4 figures, an extended version of quant-ph/0506215, to be
published in Optics Communications | null | 10.1016/j.optcom.2007.02.046 | null | quant-ph | null | We investigate a scheme of atomic quantum memory to store photonic qubits of
polarization in cavity QED. It is observed that the quantum-state swapping
between a single-photon pulse and a $ \Lambda $-type atom can be made via
scattering in an optical cavity [T. W. Chen, C. K. Law, P. T. Leung, Phys. Rev.
A {\bf 69} (2004) 063810]. This swapping operates limitedly in the strong
coupling regime for $ \Lambda $-type atoms with equal dipole couplings. We
extend this scheme in cavity QED to present a more feasible and efficient
method for quantum memory combined with projective measurement. This method
works without requiring such a condition on the dipole couplings. The fidelity
is significantly higher than that of the swapping, and even in the moderate
coupling regime it reaches almost unity by narrowing sufficiently the
photon-pulse spectrum. This high performance is rather unaffected by the atomic
loss, cavity leakage or detunings, while a trade-off is paid in the success
probability for projective measurement.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 05:09:32 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Yamada",
"Hiroyuki",
""
],
[
"Yamamoto",
"Katsuji",
""
]
] |
quant-ph/0703146 | Timur Kamalov F. | T. F. Kamalov and Yu. P. Rybakov | Probabilistic Simulation of Quantum Computation | 12 pages | Quantum Computers and Computing, 2006, v. 6, n. 1, p. 125-136 | null | null | quant-ph | null | Special stochastic representation of the wave function in Quantum Mechanics
(QM), based on soliton realization of extended particles, is suggested with the
aim to model quantum states via classical computer. Entangled solitons
construction being introduced in the nonlinear spinor field model, the
Einstein, Podolsky, Rosen (EPR) spin correlation is calculated and shown to
coincide with the quantum mechanical one for the spin-1/2 particles in the
singlet state. The concept of stochastic qubits is used for quantum computing
modelling.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 06:04:42 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kamalov",
"T. F.",
""
],
[
"Rybakov",
"Yu. P.",
""
]
] |
quant-ph/0703147 | J. Q. You | Xiao-Ling He, Yu-xi Liu, J. Q. You, Franco Nori | Variable-frequency-controlled coupling in charge qubit circuits: Effects
of microwave field on qubit-state readout | 7 pages, 3 figures | Phys. Rev. A 76, 022317 (2007) | 10.1103/PhysRevA.76.022317 | null | quant-ph cond-mat.supr-con | null | To implement quantum information processing, microwave fields are often used
to manipulate superconuducting qubits. We study how the coupling between
superconducting charge qubits can be controlled by variable-frequency magnetic
fields. We also study the effects of the microwave fields on the readout of the
charge-qubit states. The measurement of the charge-qubit states can be used to
demonstrate the statistical properties of photons.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 13:24:31 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"He",
"Xiao-Ling",
""
],
[
"Liu",
"Yu-xi",
""
],
[
"You",
"J. Q.",
""
],
[
"Nori",
"Franco",
""
]
] |
quant-ph/0703148 | Martin Strzys | M P Strzys, E M Graefe and H J Korsch | Kicked Bose-Hubbard systems and kicked tops -- destruction and
stimulation of tunneling | null | New J. Phys. 10, 013024 (2008) | 10.1088/1367-2630/10/1/013024 | null | quant-ph | null | In a two-mode approximation, Bose-Einstein condensates (BEC) in a double-well
potential can be described by a many particle Hamiltonian of Bose-Hubbard type.
We focus on such a BEC whose interatomic interaction strength is modulated
periodically by $\delta$-kicks which represents a realization of a kicked top.
In the (classical) mean-field approximation it provides a rich mixed phase
space dynamics with regular and chaotic regions. By increasing the
kick-strength a bifurcation leads to the appearance of self-trapping states
localized on regular islands. This self-trapping is also found for the many
particle system, however in general suppressed by coherent many particle
tunneling oscillations. The tunneling time can be calculated from the
quasi-energy splitting of the corresponding Floquet states. By varying the
kick-strength these quasi-energy levels undergo both avoided and even actual
crossings. Therefore stimulation or complete destruction of tunneling can be
observed for this many particle system.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 10:29:20 GMT"
},
{
"version": "v2",
"created": "Mon, 1 Oct 2007 12:09:23 GMT"
}
] | 2011-12-20T00:00:00 | [
[
"Strzys",
"M P",
""
],
[
"Graefe",
"E M",
""
],
[
"Korsch",
"H J",
""
]
] |
quant-ph/0703149 | Saifullah | Babar Ahmad, Sergei Borisenok, Saifullah, Yuri Rozhdestvensky | Open-Loop Control of Quantum Particle Motion: Effective Splitting in
Momentum Space | 8 pages, 3 figures | Journal of Prime Research in Mathematics, Vol. 2 (2006), P:
208-216 | null | null | quant-ph | null | In this paper an effective quantum particle beam-splitter in the momentum
space is realized in the frame of open-loop control scheme. We demonstrate for
small interaction time that the splitting effect $\pm40\hbar k$ with summarized
relative intensity in both main components is about 50 per cent from initial
intensity of the atomic beam.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 10:55:01 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ahmad",
"Babar",
""
],
[
"Borisenok",
"Sergei",
""
],
[
"Saifullah",
"",
""
],
[
"Rozhdestvensky",
"Yuri",
""
]
] |
quant-ph/0703150 | Matthew R. James | M.R. James, H.I. Nurdin and I.R. Petersen | H-Infinity Control of Linear Quantum Stochastic Systems | 23 pages | IEEE Transactions on Automatic Control, 53(8), 1787-1803, 2008 | null | null | quant-ph | null | The purpose of this paper is to formulate and solve a H-infinity controller
synthesis problem for a class of non-commutative linear stochastic systems
which includes many examples of interest in quantum technology. The paper
includes results on the class of such systems for which the quantum commutation
relations are preserved (such a requirement must be satisfied in a physical
quantum system). A quantum version of standard (classical) dissipativity
results are presented and from this a quantum version of the Strict Bounded
Real Lemma is derived. This enables a quantum version of the two Riccati
solution to the H-infinity control problem to be presented. This result leads
to controllers which may be realized using purely quantum, purely classical or
a mixture of quantum and classical elements. This issue of physical
realizability of the controller is examined in detail, and necessary and
sufficient conditions are given. Our results are constructive in the sense that
we provide explicit formulas for the Hamiltonian function and coupling operator
corresponding to the controller.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 11:15:21 GMT"
},
{
"version": "v2",
"created": "Thu, 3 May 2007 11:39:48 GMT"
}
] | 2009-04-09T00:00:00 | [
[
"James",
"M. R.",
""
],
[
"Nurdin",
"H. I.",
""
],
[
"Petersen",
"I. R.",
""
]
] |
quant-ph/0703151 | Rosario Lo Franco | R. Lo Franco, G. Compagno, A. Messina, and A. Napoli | Nonlocal properties of entangled two-photon generalized binomial states
in two separate cavities | 5 pages, 1 figure | Optics & Spectroscopy 103, 890 (2007) | 10.1134/S0030400X07120090 | null | quant-ph | null | We consider entangled two-photon generalized binomial states of the
electromagnetic field in two separate cavities. The nonlocal properties of this
entangled field state are analyzed by studying the electric field correlations
between the two cavities. A Bell's inequality violation is obtained using an
appropriate dichotomic cavity operator, that is in principle measurable.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 13:31:24 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Franco",
"R. Lo",
""
],
[
"Compagno",
"G.",
""
],
[
"Messina",
"A.",
""
],
[
"Napoli",
"A.",
""
]
] |
quant-ph/0703152 | R. F. O'Connell | G. W. Ford, R. F. O'Connell | Quantum thermodynamic functions for an oscillator coupled to a heat bath | Phys. Rev. B, in press | Phys. Rev. B 75, 134301 (2007) | null | null | quant-ph cond-mat.mes-hall cond-mat.stat-mech | null | Small systems (of interest in the areas of nanophysics, quantum information,
etc.) are particularly vulnerable to environmental effects. Thus, we determine
various thermodynamic functions for an oscillator in an arbitrary heat bath at
arbitrary temperatures. Explicit results are presented for the most commonly
discussed heat bath models: Ohmic, single relaxation time and blackbody
radiation.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 15:12:14 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ford",
"G. W.",
""
],
[
"O'Connell",
"R. F.",
""
]
] |
quant-ph/0703153 | Gernot Schaller | Sarah Mostame, Gernot Schaller, and Ralf Sch\"utzhold | Decoherence in the dynamical quantum phase transition of the transverse
Ising chain | 4 pages, 1 figure, minor clarifications | Physical Review A 76, 030304(R), 2007 | 10.1103/PhysRevA.76.030304 | null | quant-ph | null | For the prototypical example of the Ising chain in a transverse field, we
study the impact of decoherence on the sweep through a second-order quantum
phase transition. Apart from the advance in the general understanding of the
dynamics of quantum phase transitions, these findings are relevant for
adiabatic quantum algorithms due to the similarities between them. It turns out
that (in contrast to first-order transitions studied previously) the impact of
decoherence caused by a weak coupling to a rather general environment increases
with system size (i.e., number of spins/qubits), which might limit the
scalability of the system.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 15:35:42 GMT"
},
{
"version": "v2",
"created": "Mon, 17 Sep 2007 10:11:29 GMT"
}
] | 2007-09-17T00:00:00 | [
[
"Mostame",
"Sarah",
""
],
[
"Schaller",
"Gernot",
""
],
[
"Schützhold",
"Ralf",
""
]
] |
quant-ph/0703154 | Michel R. P. Planat | Michel R. P. Planat (FEMTO-ST), Metod Saniga (ASTRINSTSAV) | Pauli graph and finite projective lines/geometries | 12 pages | Dans Photon Counting Applications, Quantum Optics and Quantum
Cryptography - Optics and Optoelectronics, Prague : Tch\`eque, R\'epublique
(2007) | 10.1117/12.721687 | null | quant-ph math-ph math.MP | null | The commutation relations between the generalized Pauli operators of N-qudits
(i. e., N p-level quantum systems), and the structure of their maximal sets of
commuting bases, follow a nice graph theoretical/geometrical pattern. One may
identify vertices/points with the operators so that edges/lines join commuting
pairs of them to form the so-called Pauli graph P_{p^N} . As per two-qubits (p
= 2, N = 2) all basic properties and partitionings of this graph are embodied
in the geometry of the symplectic generalized quadrangle of order two, W(2).
The structure of the two-qutrit (p = 3, N = 2) graph is more involved; here it
turns out more convenient to deal with its dual in order to see all the
parallels with the two-qubit case and its surmised relation with the geometry
of generalized quadrangle Q(4, 3), the dual of W(3). Finally, the generalized
adjacency graph for multiple (N > 3) qubits/qutrits is shown to follow from
symplectic polar spaces of order two/three. The relevance of these mathematical
concepts to mutually unbiased bases and to quantum entanglement is also
highlighted in some detail.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 15:41:37 GMT"
}
] | 2011-11-09T00:00:00 | [
[
"Planat",
"Michel R. P.",
"",
"FEMTO-ST"
],
[
"Saniga",
"Metod",
"",
"ASTRINSTSAV"
]
] |
quant-ph/0703155 | Rachele Fermani | Rachele Fermani, Stefan Scheel, Peter L. Knight | Trapping cold atoms near carbon nanotubes: thermal spin flips and
Casimir-Polder potential | 8 pages, 3 figures | null | 10.1103/PhysRevA.75.062905 | null | quant-ph cond-mat.other | null | We investigate the possibility to trap ultracold atoms near the outside of a
metallic carbon nanotube (CN) which we imagine to use as a miniaturized
current-carrying wire. We calculate atomic spin flip lifetimes and compare the
strength of the Casimir-Polder potential with the magnetic trapping potential.
Our analysis indicates that the Casimir-Polder force is the dominant loss
mechanism and we compute the minimum distance to the carbon nanotube at which
an atom can be trapped.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 15:56:07 GMT"
},
{
"version": "v2",
"created": "Tue, 24 Apr 2007 13:16:31 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Fermani",
"Rachele",
""
],
[
"Scheel",
"Stefan",
""
],
[
"Knight",
"Peter L.",
""
]
] |
quant-ph/0703156 | Peyman Ahmadi | Kevin M. Fortier, Soo Y. Kim, Michael J. Gibbons, Peyman Ahmadi, and
Michael S. Chapman | Deterministic loading of individual atoms to a high-finesse optical
cavity | 10 pages, 5 figures, submitted to Phys. Rev. Lett | null | 10.1103/PhysRevLett.98.233601 | null | quant-ph | null | Individual laser cooled atoms are delivered on demand from a single atom
magneto-optic trap to a high-finesse optical cavity using an atom conveyor.
Strong coupling of the atom with the cavity field allows simultaneous cooling
and detection of individual atoms for time scales exceeding 15 s. The single
atom scatter rate is studied as a function of probe-cavity detuning and probe
Rabi frequency, and the experimental results are in good agreement with
theoretical predictions. We demonstrate the ability to manipulate the position
of a single atom relative to the cavity mode with excellent control and
reproducibility.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 20:45:28 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Fortier",
"Kevin M.",
""
],
[
"Kim",
"Soo Y.",
""
],
[
"Gibbons",
"Michael J.",
""
],
[
"Ahmadi",
"Peyman",
""
],
[
"Chapman",
"Michael S.",
""
]
] |
quant-ph/0703157 | Giovanna Morigi Dr | Giovanna Morigi, Pepijn W.H. Pinkse, Markus Kowalewski, and Regina de
Vivie-Riedle | Cavity cooling of internal molecular motion | 4 pages, 4 figures. To appear in Physical Review Letters | Phys. Rev. Lett. 99, 073001 (2007). | null | null | quant-ph physics.atom-ph | null | We predict that it is possible to cool rotational, vibrational and
translational degrees of freedom of molecules by coupling a molecular dipole
transition to an optical cavity. The dynamics is numerically simulated for a
realistic set of experimental parameters using OH molecules. The results show
that the translational motion is cooled to few $\mu$K and the internal state is
prepared in one of the two ground states of the two decoupled rotational
ladders in few seconds. Shorter cooling times are expected for molecules with
larger polarizability.
| [
{
"version": "v1",
"created": "Fri, 16 Mar 2007 21:14:19 GMT"
},
{
"version": "v2",
"created": "Mon, 9 Jul 2007 13:19:02 GMT"
}
] | 2007-08-13T00:00:00 | [
[
"Morigi",
"Giovanna",
""
],
[
"Pinkse",
"Pepijn W. H.",
""
],
[
"Kowalewski",
"Markus",
""
],
[
"de Vivie-Riedle",
"Regina",
""
]
] |
quant-ph/0703158 | Ryo Namiki | Ryo Namiki, Masato Koashi, Nobuyuki Imoto | Fidelity criterion for quantum-domain transmission and storage of
coherent states beyond unit-gain constraint | 4pages, No figures, Accepted for publication in PRL | Phys. Rev. Lett. 101, 100502 (2008). | 10.1103/PhysRevLett.101.100502 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We generalize the experimental success criterion for quantum
teleportation/memory in continuous-variable quantum systems to be suitable for
non-unit-gain condition by considering attenuation/amplification of the
coherent-state amplitude. The new criterion can be used for a non-ideal quantum
memory and long distance quantum communication as well as quantum devices with
amplification process. It is also shown that the framework to measure the
average fidelity is capable of detecting all Gaussian channels in quantum
domain.
| [
{
"version": "v1",
"created": "Sat, 17 Mar 2007 07:04:14 GMT"
},
{
"version": "v2",
"created": "Mon, 11 Aug 2008 03:52:38 GMT"
}
] | 2008-09-29T00:00:00 | [
[
"Namiki",
"Ryo",
""
],
[
"Koashi",
"Masato",
""
],
[
"Imoto",
"Nobuyuki",
""
]
] |
quant-ph/0703159 | Guang Ping He | Guang Ping He and Z. D. Wang | Single qubit quantum secret sharing with improved security | Published version | Quant. Inf. Comput. 10, 28 (2010) | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Analyzing carefully an experimentally feasible non-entangled single qubit
quantum secret sharing protocol and its modified version [Phys. Rev. Lett. 95,
230505 (2005); ibid. 98, 028902 (2007)], it is found that both versions are
insecure against coherent attacks though the original idea is so remarkable. To
overcome this fatal flaw, here we propose a protocol with a distinct security
checking strategy, which still involves single qubit operations only, making it
possible to achieve better security of quantum secret sharing with current
technology.
| [
{
"version": "v1",
"created": "Sat, 17 Mar 2007 10:21:07 GMT"
},
{
"version": "v2",
"created": "Fri, 4 Mar 2011 06:44:57 GMT"
}
] | 2011-03-07T00:00:00 | [
[
"He",
"Guang Ping",
""
],
[
"Wang",
"Z. D.",
""
]
] |
quant-ph/0703160 | W. H. Zurek | Wojciech Hubert Zurek | Quantum origin of quantum jumps: Breaking of unitary symmetry induced by
information transfer and the transition from quantum to classical | For comments see Seth Lloyd, NATURE 450, 1167 (2007) | Phys. Rev. A 76, 052110 (2007) | 10.1103/PhysRevA.76.052110 | null | quant-ph cond-mat.stat-mech hep-th | null | Measurements transfer information about a system to the apparatus, and then
further on -- to observers and (often inadvertently) to the environment. I show
that even imperfect copying essential in such situations restricts possible
unperturbed outcomes to an orthogonal subset of all possible states of the
system, thus breaking the unitary symmetry of its Hilbert space implied by the
quantum superposition principle. Preferred outcome states emerge as a result.
They provide framework for the ``wavepacket collapse'', designating terminal
points of quantum jumps, and defining the measured observable by specifying its
eigenstates. In quantum Darwinism, they are the progenitors of multiple copies
spread throughout the environment -- the fittest quantum states that not only
survive decoherence, but subvert it into carrying information about them --
into becoming a witness.
| [
{
"version": "v1",
"created": "Sat, 17 Mar 2007 16:17:35 GMT"
},
{
"version": "v2",
"created": "Mon, 19 Nov 2007 04:58:45 GMT"
},
{
"version": "v3",
"created": "Tue, 18 Mar 2008 16:43:25 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Zurek",
"Wojciech Hubert",
""
]
] |
quant-ph/0703161 | Angel S. Sanz | A. S. Sanz and S. Miret-Artes | Aspects of nonlocality from a quantum trajectory perspective: A WKB
approach to Bohmian mechanics | 11 pages (very slightly revised), 1 figure | Chem. Phys. Lett. 445, 350 (2007) | 10.1016/j.cplett.2007.08.002 | null | quant-ph | null | Nonlocality is a property of paramount importance both conceptually and
computationally exhibited by quantum systems, which has no classical
counterpart. Conceptually, it is important because it implies that the evolving
system has information on what happens at any space point and time.
Computationally, because such a knowledge makes any calculation intractable as
the number of degrees of freedom involved increases beyond a few of them.
Bohmian mechanics, with its trajectory-based formalism in real configuration
space, can help to better understand nonlocality. A detailed analysis of how
nonlocal information is transmitted to quantum trajectories in simple systems
(free particle and harmonic oscillator) turns out to be very interesting when
compared to analogous systems in classical mechanics.
| [
{
"version": "v1",
"created": "Sat, 17 Mar 2007 16:37:07 GMT"
},
{
"version": "v2",
"created": "Thu, 22 Mar 2007 17:34:17 GMT"
},
{
"version": "v3",
"created": "Fri, 7 Sep 2007 08:41:40 GMT"
}
] | 2011-11-09T00:00:00 | [
[
"Sanz",
"A. S.",
""
],
[
"Miret-Artes",
"S.",
""
]
] |
quant-ph/0703162 | Arno R Bohm | A. Bohm, H. Kaldass, S. Komy | Time Asymmetry in Quantum Physics - I. Theoretical Conclusion from
Resonance and Decay-Phenomenology | LaTeX file, 19 pages, no figs | null | null | null | quant-ph | null | It is explained how the unification of resonance and decay phenomena into a
consistent mathematical theory leads to quantum mechanical time-asymmetry. This
provides the theoretical basis for a subsequent paper II in which the
interpretation and experimental demonstration of this time-asymmetry is
discussed.
| [
{
"version": "v1",
"created": "Sun, 18 Mar 2007 00:22:44 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Bohm",
"A.",
""
],
[
"Kaldass",
"H.",
""
],
[
"Komy",
"S.",
""
]
] |
quant-ph/0703163 | Arno R Bohm | A. Bohm, H. Kaldass, S. Komy, W.P. Schleich | Time Asymmetry in Quantum Physics - II. Experimental Demonstration Using
a Single Ion | pdfLaTeX with 1 latex-fig and 2 fig files in pdf; total 3 figs | null | null | null | quant-ph | null | Quantum physics involves an ensemble of quantum systems, usually one thinks
of a large ensemble of identical quantum systems at one single time. In single
ion experiments one has a single quantum system at an ensemble of different
times. This provides the means of demonstrating the beginning of time of a
semigroup evolution for a decaying state.
| [
{
"version": "v1",
"created": "Sun, 18 Mar 2007 01:31:10 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Bohm",
"A.",
""
],
[
"Kaldass",
"H.",
""
],
[
"Komy",
"S.",
""
],
[
"Schleich",
"W. P.",
""
]
] |
quant-ph/0703164 | Aurelian Isar | A. Isar, W. Scheid | Deformed quantum harmonic oscillator with diffusion and dissipation | 14 pages | Physica A 310, 364 (2002) | 10.1016/S0378-4371(02)00775-6 | null | quant-ph | null | A master equation for the deformed quantum harmonic oscillator interacting
with a dissipative environment, in particular with a thermal bath, is derived
in the microscopic model by using perturbation theory. The coefficients of the
master equation and of equations of motion for observables depend on the
deformation function. The steady state solution of the equation for the density
matrix in the number representation is obtained and the equilibrium energy of
the deformed harmonic oscillator is calculated in the approximation of small
deformation.
| [
{
"version": "v1",
"created": "Sun, 18 Mar 2007 16:05:12 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Isar",
"A.",
""
],
[
"Scheid",
"W.",
""
]
] |
quant-ph/0703165 | Aurelian Isar | A. Isar, A. Sandulescu, W. Scheid | Lindblad master equation for the damped harmonic oscillator with
deformed dissipation | 15 pages, 2 figures | Physica A 322, 233 (2003) | 10.1016/S0378-4371(02)01828-9 | null | quant-ph | null | In the framework of the Lindblad theory for open quantum systems, a master
equation for the quantum harmonic oscillator interacting with a dissipative
environment, in particular with a thermal bath, is derived for the case when
the interaction is based on deformed algebra. The equations of motion for
observables strongly depend on the deformation function. The expectation values
of the number operator and squared number operator are calculated in the limit
of a small deformation parameter for the case of zero temperature of the
thermal bath. The steady state solution of the equation for the density matrix
in the number representation is obtained and its independence of the
deformation is shown.
| [
{
"version": "v1",
"created": "Sun, 18 Mar 2007 16:12:37 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Isar",
"A.",
""
],
[
"Sandulescu",
"A.",
""
],
[
"Scheid",
"W.",
""
]
] |
quant-ph/0703166 | Aurelian Isar | A. Isar, W. Scheid | Deformation of quantum oscillator and of its interaction with
environment | 15 pages | Physica A 335, 79 (2004) | 10.1016/j.physa.2003.12.017 | null | quant-ph | null | A master equation for the deformed quantum harmonic oscillator interacting
with a dissipative environment, in particular with a thermal bath, is derived
in the microscopic model by using perturbation theory, for the case when the
interaction is deformed. The coefficients of the master equation and of
equations of motion for observables depend on the deformation function. The
steady state solution of the equation for the density matrix in the number
representation is obtained and shown that it satisfies the detailed balance
condition. The equilibrium energy of the deformed harmonic oscillator,
calculated in the approximation of small deformation, does not depend on the
deformation of interaction operators.
| [
{
"version": "v1",
"created": "Sun, 18 Mar 2007 16:19:04 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Isar",
"A.",
""
],
[
"Scheid",
"W.",
""
]
] |
quant-ph/0703167 | Ricardo Kullock | R.Kullock, N.F.Svaiter | A Continuously Observed Two-level System Interacting with a Vacuum Field | 25 pages, no figures | null | null | CBPF-NF-027/06 | quant-ph | null | A discussion of the quantum Zeno effect and paradox is given. The quantum
Zeno paradox claims that a continuously observed system, prepared in a state
which is not an eigenstate of the Hamiltonian operator, never decays. To
recover the classical behavior of unstable systems we consider a two-level
system interacting with a Bose field, respectively prepared in the excited
state and in the Poincare invariant vacuum state. Using time-dependent
perturbation theory, we evaluate for a finite time interval the probability of
spontaneous decay of the two-level system. Using the standard argument to
obtain the quantum Zeno paradox, we consider N measurements where N goes to
infinity and we obtain that the non-decay probability law is a pure
exponential, therefore recovering the classical behavior.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 15:20:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kullock",
"R.",
""
],
[
"Svaiter",
"N. F.",
""
]
] |
quant-ph/0703168 | Miloslav Znojil | Miloslav Znojil | Determination of the domain of the admissible matrix elements in the
four-dimensional PT-symmetric anharmonic model | 18 pages, 2 figures | Physics Letters A 367 (2007) 300-306 | 10.1016/j.physleta.2007.03.010 | null | quant-ph | null | Many manifestly non-Hermitian Hamiltonians (typically, PT-symmetric complex
anharmonic oscillators) possess a strictly real, "physical" bound-state
spectrum. This means that they are (quasi-)Hermitian with respect to a suitable
non-standard metric. The domain D of the existence of this metric is studied
here for a nontrivial though still non-numerical four-parametric "benchmark"
matrix model.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 11:19:58 GMT"
}
] | 2007-07-30T00:00:00 | [
[
"Znojil",
"Miloslav",
""
]
] |
quant-ph/0703169 | Sergey Denisov | S. Denisov, L. Morales-Molina, S. Flach, and P. Hanggi | Periodically driven Quantum Ratchets: Symmetries and Resonances | 10 pages, 10 figures | Phys. Rev. A, 75 (2007) 063424 | 10.1103/PhysRevA.75.063424 | null | quant-ph cond-mat.stat-mech | null | We study the quantum version of a tilting and flashing Hamiltonian ratchets,
consisting of a periodic potential and a time-periodic driving field. The
system dynamics is governed by a Floquet evolution matrix bearing the symmetry
of the corresponding Hamiltonian. The dc-current appears due to the
desymmetrization of Floquet eigenstates, which become transporting when all the
relevant symmetries are violated. Those eigenstates which mostly contribute to
a directed transport reside in phase space regions corresponding to classical
resonances. Quantum dynamics leads to the dependence of the average velocity on
the initial phase of the ac-field. A resonant enhancement (or suppression) of
the dc-current, due to avoided crossings between different Floquet states takes
place upon tuning some control parameters. Our studies are predominantly aimed
at experimental realizations of ac-driven quantum ratchets with cold atoms.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 11:28:29 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Denisov",
"S.",
""
],
[
"Morales-Molina",
"L.",
""
],
[
"Flach",
"S.",
""
],
[
"Hanggi",
"P.",
""
]
] |
quant-ph/0703170 | Lajos Di\'osi | Lajos Di\'osi | The frictional Schr\"odinger-Newton equation in models of wave function
collapse | 6pp LaTeX for J.Phys.Conf.Ser.+2 figs. Talk given at the Int.
Workshop DICE2006 "Quantum Mechanics between Decoherence and Determinism: new
aspects from particle physics to cosmology" Piombino, Sept 11-15, 2006 | J.Phys.Conf.Ser. 67 (2007) 012024-(6) | 10.1088/1742-6596/67/1/012024 | null | quant-ph | null | Replacing the Newtonian coupling G by -iG, the Schrodinger-Newton equation
becomes ``frictional''. Instead of the reversible Schrodinger-Newton equation,
we advocate its frictional version to generate the set of pointer states for
macroscopic quantum bodies.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 12:32:38 GMT"
}
] | 2008-03-06T00:00:00 | [
[
"Diósi",
"Lajos",
""
]
] |
quant-ph/0703171 | Paolo Perinotti Dr. | G. M. D'Ariano, R. Demkowicz-Dobrzanski, P. Perinotti, and M. F.
Sacchi | Erasable and unerasable correlations | 4 pages, 2 figures | Phys. Rev. Lett. 99, 070501 (2007) | 10.1103/PhysRevLett.99.070501 | null | quant-ph | null | We address the problem of removing correlation from sets of states while
preserving as much local quantum information as possible. We prove that states
obtained from universal cloning can only be decorrelated at the expense of
complete erasure of local information (i.e. information about the copied
state). We solve analytically the problem of decorrelation for two qubits and
two qumodes (harmonic oscillators in Gaussian states), and provide sets of
decorrelable states and the minimum amount of noise to be added for
decorrelation.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 13:21:37 GMT"
},
{
"version": "v2",
"created": "Mon, 20 Aug 2007 08:18:30 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"D'Ariano",
"G. M.",
""
],
[
"Demkowicz-Dobrzanski",
"R.",
""
],
[
"Perinotti",
"P.",
""
],
[
"Sacchi",
"M. F.",
""
]
] |
quant-ph/0703172 | Pawel Maslanka | K. Bolonek, P.Kosinski | On the quantization of nonlocal theory | 9 pages, no figures; Introduction, Sec.III anf Final Remarks added;
references updated; | null | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A simple nonlocal theory is put into Hamiltonian form and quantized by using
the modern version of Ostrogradski approach.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 13:55:09 GMT"
},
{
"version": "v2",
"created": "Fri, 7 Nov 2014 13:53:57 GMT"
}
] | 2014-11-10T00:00:00 | [
[
"Bolonek",
"K.",
""
],
[
"Kosinski",
"P.",
""
]
] |
quant-ph/0703173 | Vincent Boyer | V. Boyer, C. F. McCormick, E. Arimondo, P. D. Lett | Ultraslow propagation of matched pulses by four-wave mixing in an atomic
vapor | 5 pages, 4 figures | null | 10.1103/PhysRevLett.99.143601 | null | quant-ph | null | We have observed the ultraslow propagation of matched pulses in nondegenerate
four-wave mixing in a hot atomic vapor. Probe pulses as short as 70 ns can be
delayed by a tunable time of up to 40 ns with little broadening or distortion.
During the propagation, a probe pulse is amplified and generates a conjugate
pulse which is faster and separates from the probe pulse before getting locked
to it at a fixed delay. The precise timing of this process allows us to
determine the key coefficients of the susceptibility tensor. The presence of
gain in this system makes this system very interesting in the context of
all-optical information processing.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 14:50:21 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Boyer",
"V.",
""
],
[
"McCormick",
"C. F.",
""
],
[
"Arimondo",
"E.",
""
],
[
"Lett",
"P. D.",
""
]
] |
quant-ph/0703174 | Iver Brevik | Johan S. H{\o}ye, Iver Brevik, Simen A. Ellingsen, and Jan B. Aarseth | Analytical and Numerical Verification of the Nernst Theorem for Metals | 19 pages latex, 3 figures. v4: Figures updated. This is the final
version, accepted for publication in Physical Review E | Phys.Rev.E75:051127,2007; Phys.Rev.E77:023102,2008 | 10.1103/PhysRevE.75.051127 10.1103/PhysRevE.77.023102 | null | quant-ph hep-th | null | In view of the current discussion on the subject, an effort is made to show
very accurately both analytically and numerically how the Drude dispersion
model gives consistent results for the Casimir free energy at low temperatures.
Specifically, for the free energy near T=0 we find the leading term to be
proportional to T^2 and the next-to-leading term proportional to T^{5/2}. These
terms give rise to zero Casimir entropy as T approaches zero, and is thus in
accordance with Nernst's theorem.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 14:57:08 GMT"
},
{
"version": "v2",
"created": "Sat, 31 Mar 2007 14:40:53 GMT"
},
{
"version": "v3",
"created": "Fri, 11 May 2007 16:11:46 GMT"
},
{
"version": "v4",
"created": "Sat, 12 May 2007 07:21:40 GMT"
}
] | 2015-06-30T00:00:00 | [
[
"Høye",
"Johan S.",
""
],
[
"Brevik",
"Iver",
""
],
[
"Ellingsen",
"Simen A.",
""
],
[
"Aarseth",
"Jan B.",
""
]
] |
quant-ph/0703175 | Li Chong | Di Mei, Chong Li, Guo-Hui Yang and He-Shan Song | Quantum states transfer by the analogous Bell states | 4 pages | null | 10.1088/0253-6102/49/2/20 | null | quant-ph | null | Transmitting quantum states by channels of analogous Bell states is studied
in this paper. We analyse the transmitting process, constructed the
probabilitic unitary operator, and gain the largest successful transfer quantum
state probability.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 14:57:48 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Mei",
"Di",
""
],
[
"Li",
"Chong",
""
],
[
"Yang",
"Guo-Hui",
""
],
[
"Song",
"He-Shan",
""
]
] |
quant-ph/0703176 | Li Chong | Di Mei, Chong Li and He-Shan Song | A single photon produces general W state of N qubits and its application | null | Commun. Theor. Phys. V48, pp. 75-78, (2007) | 10.1088/0253-6102/48/1/016 | null | quant-ph | null | Based on the Wu's scheme[1], We prepare the general N-qubit W state. We find
that the concurrence of two qubits in general N-qubit W state is only related
to their coefficients and we successfully apply the general N-qubit W state to
quantum state transfer and quantum state prepare like that in two-qubit system.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 15:10:10 GMT"
}
] | 2015-06-26T00:00:00 | [
[
"Mei",
"Di",
""
],
[
"Li",
"Chong",
""
],
[
"Song",
"He-Shan",
""
]
] |
quant-ph/0703177 | Oriol Romero-Isart | O. Romero-Isart, K. Eckert, C. Rod\'o, and A. Sanpera | Transport and Entanglement Generation in the Bose-Hubbard Model | 14 pages, 6 figures | J. Phys. A: Math. Theor. 40 (2007) 8019-8031 | 10.1088/1751-8113/40/28/S11 | null | quant-ph cond-mat.other | null | We study entanglement generation via particle transport across a
one-dimensional system described by the Bose-Hubbard Hamiltonian. We analyze
how the competition between interactions and tunneling affects transport
properties and the creation of entanglement in the occupation number basis.
Alternatively, we propose to use spatially delocalized quantum bits, where a
quantum bit is defined by the presence of a particle either in a site or in the
adjacent one. Our results can serve as a guidance for future experiments to
characterize entanglement of ultracold gases in one-dimensional optical
lattices.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 17:58:20 GMT"
}
] | 2007-06-27T00:00:00 | [
[
"Romero-Isart",
"O.",
""
],
[
"Eckert",
"K.",
""
],
[
"Rodó",
"C.",
""
],
[
"Sanpera",
"A.",
""
]
] |
quant-ph/0703178 | Xiaolong Deng | X.-L. Deng, D. Porras and J.I. Cirac | Quantum phases of interacting phonons in ion traps | 10 pages | Phys. Rev. A 77, 033403 (2008) | 10.1103/PhysRevA.77.033403 | null | quant-ph | null | The vibrations of a chain of trapped ions can be considered, under suitable
experimental conditions, as an ensemble of interacting phonons, whose quantum
dynamics is governed by a Bose--Hubbard Hamiltonian. In this work we study the
quantum phases which appear in this system, and show that thermodynamical
properties, such as critical parameters and critical exponents, can be measured
in experiments with a limited number of ions. Besides that, interacting phonons
in trapped ions offer us the possibility to access regimes which are difficult
to study with ultracold bosons in optical lattices, like models with attractive
or site--dependent phonon-phonon interactions.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 19:09:33 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Deng",
"X. -L.",
""
],
[
"Porras",
"D.",
""
],
[
"Cirac",
"J. I.",
""
]
] |
quant-ph/0703179 | Joy Christian | Joy Christian (Oxford) | Disproof of Bell's Theorem by Clifford Algebra Valued Local Variables | 4 pages; RevTeX4; Further elaborations may be found in
arXiv:0904.4259, arXiv:0806.3078, arXiv:0707.1333, and arXiv:quant-ph/0703244 | null | null | null | quant-ph gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is shown that Bell's theorem fails for the Clifford algebra valued local
realistic variables. This is made evident by exactly reproducing quantum
mechanical expectation value for the EPR-Bohm type spin correlations observable
by means of a local, deterministic, Clifford algebra valued variable, without
necessitating either remote contextuality or backward causation. Since Clifford
product of multivector variables is non-commutative in general, the spin
correlations derived within our locally causal model violate the CHSH
inequality just as strongly as their quantum mechanical counterparts.
| [
{
"version": "v1",
"created": "Tue, 20 Mar 2007 16:48:46 GMT"
},
{
"version": "v2",
"created": "Tue, 10 Jul 2007 03:22:59 GMT"
},
{
"version": "v3",
"created": "Thu, 22 Apr 2010 17:11:53 GMT"
}
] | 2010-04-23T00:00:00 | [
[
"Christian",
"Joy",
"",
"Oxford"
]
] |
quant-ph/0703180 | James Malley | James D. Malley | Update for "The collapse of Bell determinism" | 4 pages | null | null | null | quant-ph | null | We update our paper: The collapse of Bell determinism (Physics Letters A, 359
(2006): 122-125; available online 16 June 2006). First, we point out that
Olivier Brunet, using lattice theoretic methods, has recently, and quite
independently, derived the core technical lemma of our paper; see: A priori
knowledge and the Kochen-Specker theorem (Physics Letters A, available online 5
January 2007). He has also kindly pointed out a misstep in the last line of one
of our results. We discuss the correction and comment on slightly revised
notions of how Bell determinism collapses. We also correct a few typos in the
original paper.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 20:33:43 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Malley",
"James D.",
""
]
] |
quant-ph/0703181 | Martin Roetteler | Markus Grassl, Martin Roetteler | Quantum Block and Convolutional Codes from Self-orthogonal Product Codes | 5 pages, paper presented at the 2005 IEEE International Symposium on
Information Theory | Proceedings 2005 IEEE International Symposium on Information
Theory (ISIT 2005), Adelaide, Australia, September 2005, pp. 1018-1022 | 10.1109/ISIT.2005.1523493 | null | quant-ph cs.IT math.IT | null | We present a construction of self-orthogonal codes using product codes. From
the resulting codes, one can construct both block quantum error-correcting
codes and quantum convolutional codes. We show that from the examples of
convolutional codes found, we can derive ordinary quantum error-correcting
codes using tail-biting with parameters [[42N,24N,3]]_2. While it is known that
the product construction cannot improve the rate in the classical case, we show
that this can happen for quantum codes: we show that a code [[15,7,3]]_2 is
obtained by the product of a code [[5,1,3]]_2 with a suitable code.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 21:02:45 GMT"
}
] | 2009-05-24T00:00:00 | [
[
"Grassl",
"Markus",
""
],
[
"Roetteler",
"Martin",
""
]
] |
quant-ph/0703182 | Martin Roetteler | Markus Grassl, Martin Roetteler | Constructions of Quantum Convolutional Codes | 5 pages, to appear in the Proceedings of the 2007 IEEE International
Symposium on Information Theory | Proceedings 2007 IEEE International Symposium on Information
Theory (ISIT 2007), Nice, France, June 2007, pp. 816-820 | 10.1109/ISIT.2007.4557325 | null | quant-ph cs.IT math.IT | null | We address the problems of constructing quantum convolutional codes (QCCs)
and of encoding them. The first construction is a CSS-type construction which
allows us to find QCCs of rate 2/4. The second construction yields a quantum
convolutional code by applying a product code construction to an arbitrary
classical convolutional code and an arbitrary quantum block code. We show that
the resulting codes have highly structured and efficient encoders. Furthermore,
we show that the resulting quantum circuits have finite depth, independent of
the lengths of the input stream, and show that this depth is polynomial in the
degree and frame size of the code.
| [
{
"version": "v1",
"created": "Mon, 19 Mar 2007 21:24:36 GMT"
}
] | 2009-05-24T00:00:00 | [
[
"Grassl",
"Markus",
""
],
[
"Roetteler",
"Martin",
""
]
] |
quant-ph/0703183 | Archan S. Majumdar | Dipankar Home, Alok Kumar Pan, Md. Manirul Ali, A. S. Majumdar | Distinguishability of apparatus states in quantum measurement in the
Stern-Gerlach experiment | 8 pages, Revtex, 7 eps figures | J. Phys. A: Math. Theor. 40, 13975 (2007). | 10.1088/1751-8113/40/46/010 | null | quant-ph | null | In the context of the quantum mechanical modelling of a measurement process
using the Stern-Gerlach setup, we critically examine the relationship between
the notion of `distinguishability' of apparatus states defined in terms of the
inner product and spatial separation among the emerging wave packets. We show
that, in general, the mutual orthogonality of these wave packets does not
necessarily imply their unambiguous spatial separation even in the asymptotic
limit. A testable scheme is formulated to quantify such departures from
`idealness' for a range of relevant parameters.
| [
{
"version": "v1",
"created": "Tue, 20 Mar 2007 08:52:24 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Home",
"Dipankar",
""
],
[
"Pan",
"Alok Kumar",
""
],
[
"Ali",
"Md. Manirul",
""
],
[
"Majumdar",
"A. S.",
""
]
] |
quant-ph/0703184 | Stefano Zippilli | Stefano Zippilli, Giovanna Morigi, Helmut Ritsch | Suppression of Bragg scattering by collective interference of spatially
ordered atoms with a high-Q cavity mode | 4 pages, 5 figures | Phys. Rev. Lett. 93, 123002 (2004) | 10.1103/PhysRevLett.93.123002 | null | quant-ph | null | When N driven atoms emit in phase into a high-Q cavity mode, the intracavity
field generated by collective scattering interferes destructively with the pump
driving the atoms. Hence atomic fluorescence is suppressed and cavity loss
becomes the dominant decay channel for the whole ensemble. Microscopically 3D
light-intensity minima are formed in the vicinity of the atoms that prevent
atomic excitation and form a regular lattice. The effect gets more pronounced
for large atom numbers, when the sum of the atomic decay rates exceeds the rate
of cavity losses and one would expect the opposite behaviour. These results
provide new insight into recent experiments on collective atomic dynamics in
cavities.
| [
{
"version": "v1",
"created": "Tue, 20 Mar 2007 11:53:45 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Zippilli",
"Stefano",
""
],
[
"Morigi",
"Giovanna",
""
],
[
"Ritsch",
"Helmut",
""
]
] |
quant-ph/0703185 | Jaeyoon Cho | Jaeyoon Cho | Addressing individual atoms in optical lattices with standing-wave
driving fields | 4 pages, 3 figures; minor revisions | Phys. Rev. Lett. 99, 020502 (2007) | 10.1103/PhysRevLett.99.020502 | null | quant-ph | null | A scheme for addressing individual atoms in one- or two-dimensional optical
lattices loaded with one atom per site is proposed. The scheme is based on
position-dependent atomic population transfer induced by several standing-wave
driving fields. This allows various operations important in quantum information
processing, such as manipulation and measurement of any single atom, two-qubit
operations between any pair of adjacent atoms, and patterned loading of the
lattice with one atom per every nth site for arbitrary n. The proposed scheme
is robust against considerable imperfections and actually within reach of
current technology.
| [
{
"version": "v1",
"created": "Tue, 20 Mar 2007 12:48:09 GMT"
},
{
"version": "v2",
"created": "Sat, 14 Jul 2007 12:45:35 GMT"
}
] | 2007-07-23T00:00:00 | [
[
"Cho",
"Jaeyoon",
""
]
] |
quant-ph/0703186 | Carlos Farina | T.N.C. Mendes and C. Farina | Atom-wall dispersive forces from master equation formalism | 19 pages and 3 figures | null | 10.1088/1751-8113/40/26/016 | null | quant-ph | null | Using the general expressions for level shifts obtained from the master
equation for a small system interacting with a large one considered as a
reservoir, we calculate the dispersive potentials between an atom and a wall in
the dipole approximation. We analyze in detail the particular case of a
two-level atom in the presence of a perfectly conducting wall. We study the van
der Waals as well as the resonant interactions. All distance regimes as well as
the high and low temperature regimes are considered. We show that the
Casimir-Polder interaction can not be considered as a direct result of the
vacuum fluctuations only. Concerning the interaction between the atom and the
wall at high temperature, which show that a saturation of the potential for all
distances occurs. This saturated potential coincides exactly with that obtained
in the London-van der Waals limit.
| [
{
"version": "v1",
"created": "Tue, 20 Mar 2007 15:24:08 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Mendes",
"T. N. C.",
""
],
[
"Farina",
"C.",
""
]
] |
quant-ph/0703187 | Sheng Feng | Sheng Feng, Chao-Hsiang Chen, Geraldo A. Barbosa, Prem Kumar | The conservation of orbital angular momentum and the two-photon
detection amplitude in spontaneous parametric down-conversion | 6 pages, 3 figures, references added | null | null | null | quant-ph | null | We study the two-photon detection amplitude of the down-converted beams in
spontaneous parametric down-conversion when the physical variable of orbital
angular momentum is involved, taking into account both conservation and
non-conservation of angular momentum. Agreeing with experimental observations,
our theoretical calculation shows that spatial structure of the two-photon
detection amplitude of the down-converted beams carries important information
about conservation or non-conservation of orbital angular momentum in
spontaneous parametric down-conversion.
| [
{
"version": "v1",
"created": "Tue, 20 Mar 2007 15:30:39 GMT"
},
{
"version": "v2",
"created": "Wed, 21 Mar 2007 17:19:47 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Feng",
"Sheng",
""
],
[
"Chen",
"Chao-Hsiang",
""
],
[
"Barbosa",
"Geraldo A.",
""
],
[
"Kumar",
"Prem",
""
]
] |
quant-ph/0703188 | Zhen-Sheng Yuan | Zhen-Sheng Yuan, Yu-Ao Chen, Shuai Chen, Bo Zhao, Markus Koch,
Thorsten Strassel, Yong Zhao, Gan-Jun Zhu, J\"org Schmiedmayer, and Jian-Wei
Pan | Synchronized Independent Narrow-band Single Photons and Efficient
Generation of Photonic Entanglement | null | Phys. Rev. Lett. 98, 180503 (2007) | 10.1103/PhysRevLett.98.180503 | null | quant-ph | null | We create independent, synchronized single-photon sources with built-in
quantum memory based on two remote cold atomic ensembles. The synchronized
single photons are used to demonstrate efficient generation of entanglement.
The resulting entangled photon pairs violate a Bell's Inequality by 5 standard
deviations. Our synchronized single photons with their long coherence time of
25 ns and the efficient creation of entanglement serve as an ideal building
block for scalable linear optical quantum information processing.
| [
{
"version": "v1",
"created": "Tue, 20 Mar 2007 16:10:56 GMT"
},
{
"version": "v2",
"created": "Sat, 5 May 2007 12:06:04 GMT"
}
] | 2016-08-14T00:00:00 | [
[
"Yuan",
"Zhen-Sheng",
""
],
[
"Chen",
"Yu-Ao",
""
],
[
"Chen",
"Shuai",
""
],
[
"Zhao",
"Bo",
""
],
[
"Koch",
"Markus",
""
],
[
"Strassel",
"Thorsten",
""
],
[
"Zhao",
"Yong",
""
],
[
"Zhu",
"Gan-Jun",
""
],
[
"Schmiedmayer",
"Jörg",
""
],
[
"Pan",
"Jian-Wei",
""
]
] |
quant-ph/0703189 | Guennadi Kouzaev | G.A. Kouzaev, K.J. Sand | Quantum synapse for cold atoms | 3 figures | 5th Int. Conf. Physics, Technology and Applications of Wave
processes, Samara, Russia,Sept. 2006 | null | null | quant-ph | null | In this paper, the quantum synaptic effect is studied that arisen in the
system of two crossed wires excited by the static (DC) and radio-frequency (RF)
currents. The potential barrier between the two orthogonal atom streams is
controlled electronically and the atoms can be transferred from one wire to
another under certain critical values of the RF and DC currents. The results
are interesting in the study of quantum interferometry and quantum registering
of cold atoms.
| [
{
"version": "v1",
"created": "Tue, 20 Mar 2007 18:55:24 GMT"
},
{
"version": "v2",
"created": "Wed, 21 Mar 2007 09:19:02 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kouzaev",
"G. A.",
""
],
[
"Sand",
"K. J.",
""
]
] |
quant-ph/0703190 | Carlos Pineda | Thomas Gorin, Carlos Pineda, Thomas H. Seligman | Decoherence of an $n$-qubit quantum memory | 4 pages, 2 figures | Phys. Rev. Lett. 99, 240405 (2007) | 10.1103/PhysRevLett.99.240405 | null | quant-ph | null | We analyze decoherence of a quantum register in the absence of non-local
operations i.e. of $n$ non-interacting qubits coupled to an environment. The
problem is solved in terms of a sum rule which implies linear scaling in the
number of qubits. Each term involves a single qubit and its entanglement with
the remaining ones. Two conditions are essential: first decoherence must be
small and second the coupling of different qubits must be uncorrelated in the
interaction picture. We apply the result to a random matrix model, and
illustrate its reach considering a GHZ state coupled to a spin bath.
| [
{
"version": "v1",
"created": "Tue, 20 Mar 2007 23:45:52 GMT"
}
] | 2008-01-18T00:00:00 | [
[
"Gorin",
"Thomas",
""
],
[
"Pineda",
"Carlos",
""
],
[
"Seligman",
"Thomas H.",
""
]
] |
quant-ph/0703191 | Giuseppe Vallone | Giuseppe Vallone, Enrico Pomarico, Paolo Mataloni, Francesco De
Martini, Vincenzo Berardi | Realization and characterization of a 2-photon 4-qubit linear cluster
state | 4 pages, 4 figures | Phys. Rev. Lett. 98, 180502 (2007) | 10.1103/PhysRevLett.98.180502 | null | quant-ph | null | We report on the experimental realization of a 4-qubit linear cluster state
via two photons entangled both in polarization and linear momentum. This state
was investigated by performing tomographic measurements and by evaluating an
entanglement witness. By use of this state we carried out a novel nonlocality
proof, the so-called ``stronger two observer all versus nothing'' test of
quantum nonlocality.
| [
{
"version": "v1",
"created": "Wed, 21 Mar 2007 09:19:48 GMT"
}
] | 2008-11-05T00:00:00 | [
[
"Vallone",
"Giuseppe",
""
],
[
"Pomarico",
"Enrico",
""
],
[
"Mataloni",
"Paolo",
""
],
[
"De Martini",
"Francesco",
""
],
[
"Berardi",
"Vincenzo",
""
]
] |
quant-ph/0703192 | Vladimir Ignatovich K | V. K. Ignatovich | On EPR paradox, Bell's inequalities and experiments which prove nothing | 27 pages, 8 figures. I edited a little the text and abstract I
corrected equations (49) and (50) | Concepts of Physics, the old and new, v. 5, No 2, pp. 227-272,
2008 | 10.2478/v10005-007-0034-7 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This article shows that the there is no paradox. Violation of Bell's
inequalities should not be identified with a proof of non locality in quantum
mechanics. A number of past experiments is reviewed, and it is concluded that
the experimental results should be re-evaluated. The results of the experiments
with atomic cascade are shown not to contradict the local realism. The article
points out flaws in the experiments with down-converted photons. The
experiments with neutron interferometer on measuring the "contextuality" and
Bell-like inequalities are analyzed, and it is shown that the experimental
results can be explained without such notions. Alternative experiment is
proposed to prove the validity of local realism.
| [
{
"version": "v1",
"created": "Wed, 21 Mar 2007 15:54:53 GMT"
},
{
"version": "v2",
"created": "Tue, 6 Nov 2007 15:01:21 GMT"
},
{
"version": "v3",
"created": "Fri, 4 Jan 2008 13:20:07 GMT"
},
{
"version": "v4",
"created": "Tue, 28 Apr 2009 11:14:14 GMT"
}
] | 2010-07-20T00:00:00 | [
[
"Ignatovich",
"V. K.",
""
]
] |
quant-ph/0703193 | Rafa{\l} Demkowicz-Dobrza\'nski | Rafal Demkowicz-Dobrzanski, Piotr Kolenderski, Konrad Banaszek | Effects of imperfect noise correlations on decoherence-free subsystems:
SU(2) diffusion model | 11 pages, 6 figures, improved clarity, more discussion, many new
references and the title changed | Phys. Rev. A 76, 022302 (2007) | 10.1103/PhysRevA.76.022302 | null | quant-ph | null | We present a model of an N-qubit channel where consecutive qubits experience
correlated random rotations. Our model is an extension to the standard
decoherence-free subsystems approach (DFS) which assumes that all the qubits
experience the same disturbance. The variation of rotations acting on
consecutive qubits is modeled as diffusion on the SU(2) group. The model may be
applied to spins traveling in a varying magnetic field, or to photons passing
through a fiber whose birefringence fluctuates over the time separation between
photons. We derive an explicit formula describing the action of the channel on
an arbitrary N-qubit state. For N=3 we investigate the effects of diffusion on
both classical and quantum capacity of the channel. We observe that
nonorthogonal states are necessary to achieve the optimal classical capacity.
Furthermore we find the threshold for the diffusion parameter above which
coherent information of the channel vanishes.
| [
{
"version": "v1",
"created": "Wed, 21 Mar 2007 15:59:16 GMT"
},
{
"version": "v2",
"created": "Tue, 24 Apr 2007 17:27:00 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Demkowicz-Dobrzanski",
"Rafal",
""
],
[
"Kolenderski",
"Piotr",
""
],
[
"Banaszek",
"Konrad",
""
]
] |
quant-ph/0703194 | Phillip Kaye | Phillip Kaye | Cooling algorithms based on the 3-bit majority | 25 pages, 3 figures | null | null | null | quant-ph | null | Algorithmic cooling is a potentially important technique for making scalable
NMR quantum computation feasible in practice. Given the constraints imposed by
this approach to quantum computing, the most likely cooling algorithms to be
practicable are those based on simple reversible polarization compression (RPC)
operations acting locally on small numbers of bits. Several different
algorithms using 2- and 3-bit RPC operations have appeared in the literature,
and these are the algorithms I consider in this note. Specifically, I show that
the RPC operation used in all these algorithms is essentially a majority vote
of 3 bits, and prove the optimality of the best such algorithm. I go on to
derive some theoretical bounds on the performance of these algorithms under
some specific assumptions about errors.
| [
{
"version": "v1",
"created": "Wed, 21 Mar 2007 16:46:40 GMT"
},
{
"version": "v2",
"created": "Thu, 22 Mar 2007 13:17:22 GMT"
},
{
"version": "v3",
"created": "Tue, 15 May 2007 17:09:09 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Kaye",
"Phillip",
""
]
] |
quant-ph/0703195 | Pawel Wocjan | Thomas Decker and Pawel Wocjan | Efficient Quantum Algorithm for Hidden Quadratic and Cubic Polynomial
Function Graphs | (v2) formulated the Hidden Polynomial Function Graph Problem for
multivariate polynomials, added results on quantum query complexity,
simplified POVM substantially, (v3) derived quantum algorithm for cubic case;
16 pages | null | null | null | quant-ph | null | We introduce the Hidden Polynomial Function Graph Problem as a natural
generalization of an abelian Hidden Subgroup Problem (HSP) where the subgroups
and their cosets correspond to graphs of linear functions over the finite field
F_p. For the Hidden Polynomial Function Graph Problem the functions are not
restricted to be linear but can also be multivariate polynomial functions of
higher degree.
For a fixed number of indeterminates and bounded total degree the Hidden
Polynomial Function Graph Problem is hard on a classical computer as its black
box query complexity is polynomial in p. In contrast, this problem can be
reduced to a quantum state identification problem so that the resulting quantum
query complexity does not depend on p. For univariate polynomials we construct
a von Neumann measurement for distinguishing the states. We relate the success
probability and the implementation of this measurement to certain classical
problems involving polynomial equations. We present an efficient algorithm for
hidden quadratic and cubic function graphs by establishing that the success
probability of the measurement is lower bounded by a constant and that it can
be implemented efficiently.
| [
{
"version": "v1",
"created": "Wed, 21 Mar 2007 17:51:29 GMT"
},
{
"version": "v2",
"created": "Mon, 23 Apr 2007 17:38:28 GMT"
},
{
"version": "v3",
"created": "Wed, 16 May 2007 19:55:52 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Decker",
"Thomas",
""
],
[
"Wocjan",
"Pawel",
""
]
] |
quant-ph/0703196 | Yong Zhang | Yong Zhang (Utah), Louis H. Kauffman (UIC) | Topological-Like Features in Diagrammatical Quantum Circuits | v1: Latex. v2,v3: original proposals in v1 are stated in a physical
style. This manuscript is a formal written version of Y. Zhang's talk at the
workshop "Cats, Kets and Cloisters", Computing Laboratory, Oxford University,
July 17-23, 2006 | Quant.Inf.Proc.7:3-32,2008 | null | null | quant-ph hep-th math-ph math.MP | null | In this paper, we revisit topological-like features in the extended
Temperley--Lieb diagrammatical representation for quantum circuits including
the teleportation, dense coding and entanglement swapping. We perform these
quantum circuits and derive characteristic equations for them with the help of
topological-like operations. Furthermore, we comment on known diagrammatical
approaches to quantum information phenomena from the perspectives of both
tensor categories and topological quantum field theories. Moreover, we remark
on the proposal for categorical quantum physics and information to be described
by dagger ribbon categories.
| [
{
"version": "v1",
"created": "Wed, 21 Mar 2007 18:18:20 GMT"
},
{
"version": "v2",
"created": "Tue, 27 Mar 2007 19:58:46 GMT"
},
{
"version": "v3",
"created": "Tue, 17 Apr 2007 16:27:28 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Zhang",
"Yong",
"",
"Utah"
],
[
"Kauffman",
"Louis H.",
"",
"UIC"
]
] |
quant-ph/0703197 | Gustavo Garcia Rigolin | Goren Gordon and Gustavo Rigolin | Generalized Quantum Telecloning | 6 pages, 1 figure, RevTex4; v2: published version, 8 pages, 4
figures, RevTex4, to appear at Eur. Phys. J. D | Eur. Phys. J. D 45, 347 (2007) | 10.1140/epjd/e2007-00256-8 | null | quant-ph | null | We present a generalized telecloning (GTC) protocol where the quantum channel
is non-optimally entangled and we study how the fidelity of the telecloned
states depends on the entanglement of the channel. We show that one can
increase the fidelity of the telecloned states, achieving the optimal value in
some situations, by properly choosing the measurement basis at Alice's, albeit
turning the protocol to a probabilistic one. We also show how one can convert
the GTC protocol to the teleportation protocol via proper unitary operations.
| [
{
"version": "v1",
"created": "Wed, 21 Mar 2007 19:18:53 GMT"
},
{
"version": "v2",
"created": "Thu, 6 Sep 2007 21:25:05 GMT"
}
] | 2007-11-12T00:00:00 | [
[
"Gordon",
"Goren",
""
],
[
"Rigolin",
"Gustavo",
""
]
] |
quant-ph/0703198 | Dirk Englund | Dirk Englund, Hatice Altug, Jelena Vuckovic | Low-Threshold Surface-Passivated Photonic Crystal Nanocavity Laser | 3 pages, 2 figures | null | 10.1063/1.2769957 | null | quant-ph | null | The efficiency and operating range of a photonic crystal laser is improved by
passivating the InGaAs quantum well (QW) gain medium and GaAs membrane using an
(NH4)S treatment. The passivated laser shows a four-fold reduction in
nonradiative surface recombination rate, resulting in a four-fold reduction in
lasing threshold. A three-level carrier dynamics model explains the results and
shows that lasing threshold is as much determined by surface recombination
losses as by the cavity quality factor (Q). Surface passivation therefore
appears crucial in operating such lasers under practical conditions.
| [
{
"version": "v1",
"created": "Wed, 21 Mar 2007 19:48:57 GMT"
},
{
"version": "v2",
"created": "Wed, 21 Mar 2007 20:18:24 GMT"
},
{
"version": "v3",
"created": "Thu, 21 Jun 2007 10:32:26 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Englund",
"Dirk",
""
],
[
"Altug",
"Hatice",
""
],
[
"Vuckovic",
"Jelena",
""
]
] |
quant-ph/0703199 | Philipp Treutlein | Philipp Treutlein, David Hunger, Stephan Camerer, Theodor W. H\"ansch,
and Jakob Reichel | Bose-Einstein condensate coupled to a nanomechanical resonator on an
atom chip | published version (5 pages, 3 figures) | Phys. Rev. Lett. 99, 140403 (2007) | 10.1103/PhysRevLett.99.140403 | null | quant-ph | null | We theoretically study the coupling of Bose-Einstein condensed atoms to the
mechanical oscillations of a nanoscale cantilever with a magnetic tip. This is
an experimentally viable hybrid quantum system which allows one to explore the
interface of quantum optics and condensed matter physics. We propose an
experiment where easily detectable atomic spin-flips are induced by the
cantilever motion. This can be used to probe thermal oscillations of the
cantilever with the atoms. At low cantilever temperatures, as realized in
recent experiments, the backaction of the atoms onto the cantilever is
significant and the system represents a mechanical analog of cavity quantum
electrodynamics. With high but realistic cantilever quality factors, the strong
coupling regime can be reached, either with single atoms or collectively with
Bose-Einstein condensates. We discuss an implementation on an atom chip.
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 18:13:52 GMT"
},
{
"version": "v2",
"created": "Mon, 9 Jul 2007 18:02:50 GMT"
},
{
"version": "v3",
"created": "Thu, 4 Oct 2007 09:43:10 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Treutlein",
"Philipp",
""
],
[
"Hunger",
"David",
""
],
[
"Camerer",
"Stephan",
""
],
[
"Hänsch",
"Theodor W.",
""
],
[
"Reichel",
"Jakob",
""
]
] |
quant-ph/0703200 | Leonardo Antonio Mendes de Souza | K. M. Fonseca Romero, J. E. Parreira, L. A. M. Souza, M. C. Nemes, and
W. F. Wreszinski | An analytical relation between entropy production and quantum Lyapunov
exponents for Gaussian bipartite systems | 9 pages, 1 figure, published version | J. Phys. A: Math. Theor. 41 115303 (9pp) (2008) | 10.1088/1751-8113/41/11/115303 | null | quant-ph | null | We study and compare the information loss of a large class of Gaussian
bipartite systems. It includes the usual Caldeira-Leggett type model as well as
Anosov models (parametric oscillators, the inverted oscillator environment,
etc), which exhibit instability, one of the most important characteristics of
chaotic systems. We establish a rigorous connection between the quantum
Lyapunov exponents and coherence loss, and show that in the case of unstable
environments coherence loss is completely determined by the upper quantum
Lyapunov exponent, a behavior which is more universal than that of the
Caldeira-Leggett type model.
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 02:31:23 GMT"
},
{
"version": "v2",
"created": "Thu, 28 Jun 2007 16:31:06 GMT"
},
{
"version": "v3",
"created": "Fri, 28 Mar 2008 15:47:21 GMT"
}
] | 2008-03-31T00:00:00 | [
[
"Romero",
"K. M. Fonseca",
""
],
[
"Parreira",
"J. E.",
""
],
[
"Souza",
"L. A. M.",
""
],
[
"Nemes",
"M. C.",
""
],
[
"Wreszinski",
"W. F.",
""
]
] |
quant-ph/0703201 | Geng Hua Yun | H. Y. Geng | Covariant path integral formalism of relativistic quantum mechanics
along proper time | 9 pages, 1 figure | null | null | null | quant-ph math-ph math.MP | null | A space-time symmetric and explicitly Lorentz covariant path integral
formalism of relativistic quantum mechanics is proposed, which produces partial
locally correlations of quantum processes of massive particles with the
velocity of light at low energy limits. A superluminal correlation is also
possible if anti-particles that moving along reverse time direction are
excited. This provides a new point of view to interpret EPR experiments, also
leaks a light of hope for hidden variable theories.
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 07:16:46 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Geng",
"H. Y.",
""
]
] |
quant-ph/0703202 | Marco Roncaglia | L. Campos Venuti, C. Degli Esposti Boschi, M. Roncaglia | Qubit Teleportation and Transfer across Antiferromagnetic Spin Chains | 5 pages, 4 .eps figures | Phys. Rev. Lett. 99, 060401 (2007) | 10.1103/PhysRevLett.99.060401 | null | quant-ph cond-mat.str-el | null | We explore the capability of spin-1/2 chains to act as quantum channels for
both teleportation and transfer of qubits. Exploiting the emergence of
long-distance entanglement in low-dimensional systems [Phys. Rev. Lett. 96,
247206 (2006)], here we show how to obtain high communication fidelities
between distant parties. An investigation of protocols of teleportation and
state transfer is presented, in the realistic situation where temperature is
included. Basing our setup on antiferromagnetic rotationally invariant systems,
both protocols are represented by pure depolarizing channels. We propose a
scheme where channel fidelity close to one can be achieved on very long chains
at moderately small temperature.
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 11:09:31 GMT"
},
{
"version": "v2",
"created": "Wed, 4 Apr 2007 13:08:45 GMT"
}
] | 2007-08-16T00:00:00 | [
[
"Venuti",
"L. Campos",
""
],
[
"Boschi",
"C. Degli Esposti",
""
],
[
"Roncaglia",
"M.",
""
]
] |
quant-ph/0703203 | Johan Aberg | Johan Aberg, Daniel K. L. Oi | Generalized spectroscopy; coherence, superposition, and loss | null | null | null | null | quant-ph | null | We analyze single particle coherence and interference in the presence of
particle loss and derive an inequality that relates the preservation of
coherence, the creation of superposition with the vacuum, and the degree of
particle loss. We find that loss channels constructed using linear optics form
a special subclass. We suggests a generalized spectroscopy where, in analogy
with the absorption spectrum, we measure a "coherence loss spectrum" and a
"superposition creation spectrum". The theory is illustrated with examples.
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 12:01:36 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Aberg",
"Johan",
""
],
[
"Oi",
"Daniel K. L.",
""
]
] |
quant-ph/0703204 | Zeqian Chen | Zeqian Chen | von Neumann-Landau equation for wave functions, wave-particle duality
and collapses of wave functions | 4 pages | null | null | null | quant-ph | null | It is shown that von Neumann-Landau equation for wave functions can present a
mathematical formalism of motion of quantum mechanics. The wave functions of
von Neumann-Landau equation for a single particle are `bipartite', in which the
associated Schr\"{o}dinger's wave functions correspond to those `bipartite'
wave functions of product forms. This formalism establishes a mathematical
expression of wave-particle duality and that von Neumann's entropy is a
quantitative measure of complementarity between wave-like and particle-like
behaviors. Furthermore, this extension of Schr\"{o}dinger's form suggests that
collapses of Schr\"{o}dinger's wave functions can be regarded as the
simultaneous transition of the particle from many levels to one.
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 14:12:43 GMT"
},
{
"version": "v2",
"created": "Sat, 29 Sep 2007 07:53:02 GMT"
}
] | 2007-09-29T00:00:00 | [
[
"Chen",
"Zeqian",
""
]
] |
quant-ph/0703205 | Roger Andrews Dr | C. Gopaul and R. Andrews | The effect of atmospheric turbulence on entangled orbital angular
momentum states | To appear in New Journal of Physics | null | 10.1088/1367-2630/9/4/094 | null | quant-ph | null | We analyze the effect of atmospheric Kolmogorov turbulence on entangled
orbital angular momentum states generated by parametric down-conversion. We
calculate joint and signal photon detection probabilities and obtain
numerically their dependence on the mode-width-to-Fried-parameter ratio. We
demonstrate that entangled photons are less robust to the effects of Kolmogorov
turbulence compared to single photons. In contrast, signal photons are more
robust than single photons in the lowest-order mode. We also obtain numerically
a scaling relation between the value of the mode-width-to-Fried-parameter ratio
for which the joint detection probabilities is a maximum and the momentum
mismatch between signal and idler photons after propagation through the medium.
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 14:14:19 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Gopaul",
"C.",
""
],
[
"Andrews",
"R.",
""
]
] |
quant-ph/0703206 | Emilio Santos Corchero | Emilio Santos | A local hidden variables model for the measured EPR-type flavour
entanglement in upsilon(4S)->B0B0bar decays | 4 pages, no figures | null | null | null | quant-ph | null | A local hidden variables model is exhibited which gives predictions in
agreement with the quantum ones for the recent experiment by Go et al.
quant-ph/0702267
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 16:26:35 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Santos",
"Emilio",
""
]
] |
quant-ph/0703207 | Giacomo Ciaramicoli | G. Ciaramicoli, I. Marzoli, and P. Tombesi | Spin chains with electrons in Penning traps | 21 pages, 1 figure, accepted for publication in PRA | null | null | null | quant-ph | null | We demonstrate that spin chains are experimentally feasible using electrons
confined in micro-Penning traps, supplemented with local magnetic field
gradients. The resulting Heisenberg-like system is characterized by coupling
strengths showing a dipolar decay. These spin chains can be used as a channel
for short distance quantum communication. Our scheme offers high accuracy in
reproducing an effective spin chain with relatively large transmission rate.
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 16:54:01 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ciaramicoli",
"G.",
""
],
[
"Marzoli",
"I.",
""
],
[
"Tombesi",
"P.",
""
]
] |
quant-ph/0703208 | Andrei Galiautdinov | Andrei Galiautdinov and Michael Geller | Controlled-NOT gate design for Josephson phase qubits with tunable
inductive coupling: Weyl chamber steering and area theorem | 5 pages, no figures | null | null | null | quant-ph | null | Superconducting qubits with tunable coupling are ideally suited for fast and
accurate implementation of quantum logic. Here we present a simple approach,
based on Weyl chamber steering, to CNOT gate design for inductively coupled
phase qubits with tunable coupling strength g. In the presence of simultaneous
rf pulses on the individual qubits that appropriately track the coupling
strength as it is varied, we show that an infinite family of switching
sequences preserving the time integral or "area" of g can be used to generate
CNOT logic. We demonstrate our approach by considering time-dependencies most
likely to be used in actual implementations: trapezoidal, sine, and soft
quartic (also known as Landau's hat).
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 17:39:36 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Galiautdinov",
"Andrei",
""
],
[
"Geller",
"Michael",
""
]
] |
quant-ph/0703209 | Tobias J. Osborne | Christian K. Burrell and Tobias J. Osborne | Bounds on Information Propagation in Disordered Quantum Spin Chains | 4 pages, pdflatex, 1 pdf figure. Corrected the bound for the
localised propagator and quantified the probability it bound occurs | Phys. Rev. Lett. 99, 167201 (2007) | 10.1103/PhysRevLett.99.167201 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the propagation of information through the disordered XY
model. We find, with a probability that increases with the size of the system,
that all correlations, both classical and quantum, are suppressed outside of an
effective lightcone whose radius grows at most polylogarithmically with |t|.
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 18:28:51 GMT"
},
{
"version": "v2",
"created": "Fri, 4 May 2007 13:53:20 GMT"
},
{
"version": "v3",
"created": "Thu, 21 Jul 2011 09:02:36 GMT"
}
] | 2011-07-22T00:00:00 | [
[
"Burrell",
"Christian K.",
""
],
[
"Osborne",
"Tobias J.",
""
]
] |
quant-ph/0703210 | Robert Koenig | Robert Koenig and Graeme Mitchison | A most compendious and facile quantum de Finetti theorem | 17 pages, 3 figures | J. Math. Phys. 50, 012105 (2009) | null | null | quant-ph | null | In its most basic form, the finite quantum de Finetti theorem states that the
reduced k-partite density operator of an n-partite symmetric state can be
approximated by a convex combination of k-fold product states. Variations of
this result include Renner's "exponential" approximation by "almost-product"
states, a theorem which deals with certain triples of representations of the
unitary group, and D'Cruz et al.'s result for infinite-dimensional systems. We
show how these theorems follow from a single, general de Finetti theorem for
representations of symmetry groups, each instance corresponding to a particular
choice of symmetry group and representation of that group. This gives some
insight into the nature of the set of approximating states, and leads to some
new results, including an exponential theorem for infinite-dimensional systems.
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 19:06:30 GMT"
}
] | 2009-01-12T00:00:00 | [
[
"Koenig",
"Robert",
""
],
[
"Mitchison",
"Graeme",
""
]
] |
quant-ph/0703211 | Dmitri Maslov | D. Maslov | Linear Depth Stabilizer and Quantum Fourier Transformation Circuits with
no Auxiliary Qubits in Finite Neighbor Quantum Architectures | 8 pages, 6 figures. Extended discussions, improved presentation | Phys. Rev. A 76, 052310 (2007) | 10.1103/PhysRevA.76.052310 | null | quant-ph | null | In this paper, we investigate how quantum architectures affect the efficiency
of the execution of the quantum Fourier transform (QFT) and linear
transformations, which are essential parts of the stabilizer/Clifford group
circuits. In particular, we show that in most common and realistic physical
architectures including the linear nearest neighbor, two-dimensional lattice,
and bounded degree graph (containing a chain of length n), n-qubit QFT and
n-qubit stabilizer circuits can be parallelized to linear depth using no
auxiliary qubits. We construct lower bounds that show the efficiency of our
approach.
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 19:45:06 GMT"
},
{
"version": "v2",
"created": "Thu, 15 Nov 2007 20:38:20 GMT"
}
] | 2007-11-15T00:00:00 | [
[
"Maslov",
"D.",
""
]
] |
quant-ph/0703212 | Sheng Feng | Sheng Feng, Chao-Hsiang Chen, Geraldo A. Barbosa, Prem Kumar | Is orbital angular momentum always conserved in spontaneous parametric
down-conversion? | 4 pages, 3 figures, submitted to Phys. Rev. Lett. Revised | null | 10.1117/12.734118 | null | quant-ph | null | In the non-linear optical process of type-II spontaneous parametric
down-conversion, we present on an experiment showing that the two-photon
detection amplitude of the down-converted beams does not generally reproduce
the transverse profile of the pump beam that carries non-zero orbital angular
momentum. We explain this observation by that orbital angular momentum is not
conserved in the type-II non-linear process due to the broken rotational
symmetry of the Hamiltonian.
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 19:53:49 GMT"
},
{
"version": "v2",
"created": "Fri, 20 Apr 2007 19:11:04 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Feng",
"Sheng",
""
],
[
"Chen",
"Chao-Hsiang",
""
],
[
"Barbosa",
"Geraldo A.",
""
],
[
"Kumar",
"Prem",
""
]
] |
quant-ph/0703213 | Andreas Klappenecker | Andreas Klappenecker, Pradeep Kiran Sarvepalli | On Subsystem Codes Beating the Hamming or Singleton Bound | 18 pages more densely packed than classically possible | null | 10.1098/rspa.2007.0028 | null | quant-ph | null | Subsystem codes are a generalization of noiseless subsystems, decoherence
free subspaces, and quantum error-correcting codes. We prove a Singleton bound
for GF(q)-linear subsystem codes. It follows that no subsystem code over a
prime field can beat the Singleton bound. On the other hand, we show the
remarkable fact that there exist impure subsystem codes beating the Hamming
bound. A number of open problems concern the comparison in performance of
stabilizer and subsystem codes. One of the open problems suggested by Poulin's
work asks whether a subsystem code can use fewer syndrome measurements than an
optimal MDS stabilizer code while encoding the same number of qudits and having
the same distance. We prove that linear subsystem codes cannot offer such an
improvement under complete decoding.
| [
{
"version": "v1",
"created": "Thu, 22 Mar 2007 23:32:08 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Klappenecker",
"Andreas",
""
],
[
"Sarvepalli",
"Pradeep Kiran",
""
]
] |
quant-ph/0703214 | Galina L. Klimchitskaya | G.L.Klimchitskaya and V.M.Mostepanenko | Comment on ``Analytical and numerical verification of the Nernst heat
theorem for metals'' | 6 pages | Phys.Rev.E77:023101,2008 | 10.1103/PhysRevE.77.023101 | null | quant-ph astro-ph cond-mat.stat-mech hep-th | null | Recently, H{\o}ye, Brevik, Ellingsen and Aarseth (quant-ph/0703174) claimed
that the use of the Drude dielectric function leads to zero Casimir entropy at
zero temperature in accordance with Nernst's theorem. We demonstrate that their
proof is not applicable to metals with perfect crystal lattices having no
impurities. Thus there is no any contradiction with previous results in the
literature proving that the Drude dielectric function violates the Nernst
theorem for the Casimir entropy in the case of perfect crystal lattices. We
also indicate mistakes in the coefficients of their asymptotic expressions for
metals with impurities.
| [
{
"version": "v1",
"created": "Fri, 23 Mar 2007 00:14:30 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Klimchitskaya",
"G. L.",
""
],
[
"Mostepanenko",
"V. M.",
""
]
] |
quant-ph/0703215 | Dmytro Gavinsky | Dmytro Gavinsky | Classical Interaction Cannot Replace a Quantum Message | Corrected typos, improved readability | null | null | null | quant-ph cs.CC | null | We demonstrate a two-player communication problem that can be solved in the
one-way quantum model by a 0-error protocol of cost O (log n) but requires
exponentially more communication in the classical interactive (bounded error)
model.
| [
{
"version": "v1",
"created": "Fri, 23 Mar 2007 01:38:13 GMT"
},
{
"version": "v2",
"created": "Sun, 8 Jul 2007 03:01:46 GMT"
},
{
"version": "v3",
"created": "Thu, 21 Feb 2008 05:51:12 GMT"
}
] | 2022-03-29T00:00:00 | [
[
"Gavinsky",
"Dmytro",
""
]
] |
quant-ph/0703216 | Kevin Ann | Kevin Ann, Gregg Jaeger | Disentanglement and decoherence in two-spin and three-spin systems under
dephasing | 17 pages | Physical Review B 75, 115307 (2007) | 10.1103/PhysRevB.75.115307 | null | quant-ph | null | We compare disentanglement and decoherence rates within two-spin and
three-spin entangled systems subjected to all possible combinations of local
and collective pure dephasing noise combinations. In all cases, the bipartite
entanglement decay rate is found to be greater than or equal to the
dephasing-decoherence rates and often significantly greater. This sharpens
previous results for two-spin systems [T. Yu and J. H. Eberly Phys. Rev. B 68,
165322 (2003)] and extends them to the three-spin context.
| [
{
"version": "v1",
"created": "Fri, 23 Mar 2007 04:48:26 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ann",
"Kevin",
""
],
[
"Jaeger",
"Gregg",
""
]
] |
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