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2025-04-04 00:00:00
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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/0607039
|
Graeme Smith
|
Graeme Smith, John A. Smolin and Andreas Winter
|
The quantum capacity with symmetric side channels
|
10 pages, 4 figures
|
IEEE Trans. Info. Theory 54, 9, 4208-4217 (2008)
|
10.1109/TIT.2008.928269
| null |
quant-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present an upper bound for the quantum channel capacity that is both
additive and convex. Our bound can be interpreted as the capacity of a channel
for high-fidelity quantum communication when assisted by a family of channels
that have no capacity on their own. This family of assistance channels, which
we call symmetric side channels, consists of all channels mapping symmetrically
to their output and environment. The bound seems to be quite tight, and for
degradable quantum channels it coincides with the unassisted channel capacity.
Using this symmetric side channel capacity, we find new upper bounds on the
capacity of the depolarizing channel. We also briefly indicate an analogous
notion for distilling entanglement using the same class of (one-way) channels,
yielding one of the few entanglement measures that is monotonic under local
operations with one-way classical communication (1-LOCC), but not under the
more general class of local operations with classical communication (LOCC).
|
[
{
"version": "v1",
"created": "Wed, 5 Jul 2006 21:43:39 GMT"
},
{
"version": "v2",
"created": "Fri, 7 Jul 2006 00:45:33 GMT"
},
{
"version": "v3",
"created": "Thu, 28 Aug 2008 15:12:37 GMT"
}
] | 2008-08-28T00:00:00 |
[
[
"Smith",
"Graeme",
""
],
[
"Smolin",
"John A.",
""
],
[
"Winter",
"Andreas",
""
]
] |
quant-ph/0607040
|
A. D. Alhaidari
|
A. D. Alhaidari
|
Representation reduction and solution space contraction in quasi-exactly
solvable systems
|
25 pages, 4 figures (2 in color)
|
J. Phys. A: Math. Theor. 40 (2007) 6305-6328
|
10.1088/1751-8113/40/24/004
| null |
quant-ph
| null |
In quasi-exactly solvable problems partial analytic solution (energy spectrum
and associated wavefunctions) are obtained if some potential parameters are
assigned specific values. We introduce a new class in which exact solutions are
obtained at a given energy for a special set of values of the potential
parameters. To obtain a larger solution space one varies the energy over a
discrete set (the spectrum). A unified treatment that includes the standard as
well as the new class of quasi-exactly solvable problems is presented and few
examples (some of which are new) are given. The solution space is spanned by
discrete square integrable basis functions in which the matrix representation
of the Hamiltonian is tridiagonal. Imposing quasi-exact solvability constraints
result in a complete reduction of the representation into the direct sum of a
finite and infinite component. The finite is real and exactly solvable, whereas
the infinite is complex and associated with zero norm states. Consequently, the
whole physical space contracts to a finite dimensional subspace with
normalizable states.
|
[
{
"version": "v1",
"created": "Wed, 5 Jul 2006 22:21:11 GMT"
}
] | 2007-06-13T00:00:00 |
[
[
"Alhaidari",
"A. D.",
""
]
] |
quant-ph/0607041
|
Yu Tong
|
Yu Tong, Ruibao Tao
|
Non-adiabatic Arbitary Geometric Gates in 2-qubit NMR Model
|
7 pages, 1 figure
| null |
10.1142/S0217984907013353
| null |
quant-ph
| null |
We study a 2-qubit nuclear spin system for realizing an arbitrary geometric
quantum phase gate by means of non-adiabatic operation. A single magnetic pulse
with multi harmonic frequencies is applied to manipulate the quantum states of
2-qubit instantly. Using resonant transition approximation, the time dependent
Hamiltonian of two nuclear spins can be solved analytically. The time evolution
of the wave function is obtained without adiabatic approximation. The
parameters of magnetic pulse, such as the frequency, amplitude, phase of each
harmonic part as well as the time duration of the pulse, are determined for
achieving an arbitrary non-adiabatic geometric phase gate. The derivation of
non-adiabatic geometric controlled phase gates and A-A phase are also
addressed.
|
[
{
"version": "v1",
"created": "Thu, 6 Jul 2006 03:09:48 GMT"
},
{
"version": "v2",
"created": "Wed, 6 Sep 2006 09:12:56 GMT"
},
{
"version": "v3",
"created": "Sat, 16 Dec 2006 09:13:51 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Tong",
"Yu",
""
],
[
"Tao",
"Ruibao",
""
]
] |
quant-ph/0607042
|
Xiaoyu Chen
|
Xiao-yu Chen
|
The condition for entanglement enhanced information transmission of
Pauli memory channel
|
5 pages
| null |
10.1016/j.physleta.2006.09.026
| null |
quant-ph
| null |
The sufficient condition of entanglement enhanced classical capacity is given
for Pauli memory channel with arbitrary channel parameters. In some special
case the condition is also necessary but fail to be necessary in general. The
theory of majorization and perturbation are used in the proving.
|
[
{
"version": "v1",
"created": "Thu, 6 Jul 2006 03:25:37 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Chen",
"Xiao-yu",
""
]
] |
quant-ph/0607043
|
Zheng-Yuan Xue
|
Zheng-Yuan Xue, Gang Zhang, Ping Dong, You-Min Yi, Zhuo-Liang Cao
|
Quantum controlled phase gate and cluster states generation via two
superconducting quantum interference devices in a cavity
|
4 pages, resumitted
|
Eur. Phys. J. B 52, 333 (2006).
|
10.1140/epjb/e2006-00297-3
| null |
quant-ph
| null |
A scheme for implementing 2-qubit quantum controlled phase gate (QCPG) is
proposed with two superconducting quantum interference devices (SQUIDs) in a
cavity. The gate operations are realized within the two lower flux states of
the SQUIDs by using a quantized cavity field and classical microwave pulses.
Our scheme is achieved without any type of measurement, does not use the cavity
mode as the data bus and only requires a very short resonant interaction of the
SQUID-cavity system. As an application of the QCPG operation, we also propose a
scheme for generating the cluster states of many SQUIDs.
|
[
{
"version": "v1",
"created": "Thu, 6 Jul 2006 13:16:21 GMT"
}
] | 2011-11-09T00:00:00 |
[
[
"Xue",
"Zheng-Yuan",
""
],
[
"Zhang",
"Gang",
""
],
[
"Dong",
"Ping",
""
],
[
"Yi",
"You-Min",
""
],
[
"Cao",
"Zhuo-Liang",
""
]
] |
quant-ph/0607044
|
Elias Gyftopoulos
|
Elias P. Gyftopoulos
|
Thermodynamic and Quantum Thermodynamic Analyses of Brownian Movement
| null | null | null | null |
quant-ph
| null |
Thermodynamic and quantum thermodynamic analyses of Brownian movement of a
solvent and a colloid passing through neutral thermodynamic equilibrium states
only. It is shown that Brownian motors and E. coli do not represent Brownian
movement.
|
[
{
"version": "v1",
"created": "Thu, 6 Jul 2006 14:59:21 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Gyftopoulos",
"Elias P.",
""
]
] |
quant-ph/0607045
|
Oleksandr Zhmudskyy O
|
K. S. Karplyuk and O. O. Zhmudskyy
|
Hypercomplex Dirac Equation and Electrodynamics of Non-Conserved Charges
|
10 pages
| null | null | null |
quant-ph
| null |
It is shown that the hypercomplex Dirac equation describes the system of
connected fields: 4-scalar, 4-pseudoscalar, 4-vector, 4-pseudo-vector and
antisymmetric 4-tensor second rank field. If mass is assumed to be zero this
system splits into two subsystems. Equations containing tensor, scalar and
pseudoscalar fields coincide with Maxwell equations complemented by scalar and
pseudoscalar fields. This system describes the electrodynamics of non-conserved
charges. The scalar and pseudoscalar fields are generated only by the
non-conserved charges - electric and hypothetical magnetic. The influence of
these fields on the charged particles is very unusual - it causes a change of
their rest mass. This allows us to give a new look at the Wigner paradox and
mechanism of mass renormalization.
|
[
{
"version": "v1",
"created": "Thu, 6 Jul 2006 19:05:20 GMT"
},
{
"version": "v2",
"created": "Tue, 11 Jul 2006 16:38:53 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Karplyuk",
"K. S.",
""
],
[
"Zhmudskyy",
"O. O.",
""
]
] |
quant-ph/0607046
|
Samuel J. Lomonaco jr
|
Samuel J. Lomonaco Jr., Louis H. Kauffman
|
Quantum Hidden Subgroup Algorithms: An Algorithmic Toolkit
|
34 pages, 8 figures
| null | null | null |
quant-ph
| null |
One of the most promising and versatile approaches to creating new quantum
algorithms is based on the quantum hidden subgroup (QHS) paradigm, originally
suggested by Alexei Kitaev. This class of quantum algorithms encompasses the
Deutsch-Jozsa, Simon, Shor algorithms, and many more.
In this paper, our strategy for finding new quantum algorithms is to
decompose Shor's quantum factoring algorithm into its basic primitives, then to
generalize these primitives, and finally to show how to reassemble them into
new QHS algorithms. Taking an "alphabetic building blocks approach," we use
these primitives to form an "algorithmic toolkit" for the creation of new
quantum algorithms, such as wandering Shor algorithms, continuous Shor
algorithms, the quantum circle algorithm, the dual Shor algorithm, a QHS
algorithm for Feynman integrals, free QHS algorithms, and more.
Toward the end of this paper, we show how Grover's algorithm is most
surprisingly "almost" a QHS algorithm, and how this result suggests the
possibility of an even more complete "algorithmic tookit" beyond the QHS
algorithms.
|
[
{
"version": "v1",
"created": "Thu, 6 Jul 2006 18:50:51 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Lomonaco",
"Samuel J.",
"Jr."
],
[
"Kauffman",
"Louis H.",
""
]
] |
quant-ph/0607047
|
David DiVincenzo
|
David P. DiVincenzo and Panos Aliferis
|
Effective fault-tolerant quantum computation with slow measurements
|
9 pages, 11 figures. v2: small changes and reference additions
|
Phys. Rev. Lett. 98 (2007) 220501
|
10.1103/PhysRevLett.98.020501
| null |
quant-ph
| null |
How important is fast measurement for fault-tolerant quantum computation?
Using a combination of existing and new ideas, we argue that measurement times
as long as even 1,000 gate times or more have a very minimal effect on the
quantum accuracy threshold. This shows that slow measurement, which appears to
be unavoidable in many implementations of quantum computing, poses no essential
obstacle to scalability.
|
[
{
"version": "v1",
"created": "Thu, 6 Jul 2006 18:57:45 GMT"
},
{
"version": "v2",
"created": "Thu, 3 Aug 2006 15:00:53 GMT"
}
] | 2007-10-09T00:00:00 |
[
[
"DiVincenzo",
"David P.",
""
],
[
"Aliferis",
"Panos",
""
]
] |
quant-ph/0607048
|
Michael Uleysky
|
V.Yu. Argonov and S.V. Prants
|
Nonlinear coherent dynamics of an atom in an optical lattice
| null |
V.Yu. Argonov and S.V. Prants. Nonlinear coherent dynamics of an
atom in an optical lattice. Journal of Russian Laser Research. V.27 N4 (2006)
360-378.
| null | null |
quant-ph nlin.CD
| null |
We consider a simple model of lossless interaction between a two-level single
atom and a standing-wave single-mode laser field which creates a
one-dimensional optical lattice. Internal dynamics of the atom is governed by
the laser field which is treated to be classical with a large number of
photons. Center-of-mass classical atomic motion is governed by the optical
potential and the internal atomic degree of freedom. The resulting
Hamilton-Schr\"odinger equations of motion are a five-dimensional nonlinear
dynamical system with two integrals of motion. The main focus of the paper is
chaotic atomic motion that may be quantified strictly by positive values of the
maximal Lyapunov exponent. It is shown that atom, depending on the value of its
total energy, can either oscillate chaotically in a well of the optical
potential or fly ballistically with weak chaotic oscillations of its momentum
or wander in the optical lattice changing the direction of motion in a chaotic
way. In the regime of chaotic wandering atomic motion is shown to have fractal
properties. We find a useful tool to visualize complicated atomic motion --
Poincar\'e mapping of atomic trajectories in an effective three-dimensional
phase space onto planes of atomic internal variables and momentum. We find
common features with typical non-hyperbolic Hamiltonian systems -- chains of
resonant islands of different sizes embedded in a stochastic sea, stochastic
layers, bifurcations, and so on. The phenomenon of sticking of atomic
trajectories to boundaries of regular islands, that should have a great
influence to atomic transport in optical lattices, is found and demonstrated
numerically.
|
[
{
"version": "v1",
"created": "Thu, 6 Jul 2006 23:22:46 GMT"
}
] | 2011-11-09T00:00:00 |
[
[
"Argonov",
"V. Yu.",
""
],
[
"Prants",
"S. V.",
""
]
] |
quant-ph/0607049
|
Roberto Floreanini
|
F. Benatti and R. Floreanini
|
Asymptotic Entanglement of Two Independent Systems in a Common Bath
|
10 pages, LaTeX
| null | null | null |
quant-ph cond-mat.other hep-th
| null |
Two, non-interacting systems immersed in a common bath and evolving with a
Markovian, completely positive dynamics can become initially entangled via a
purely noisy mechanism. Remarkably, for certain, phenomenologically relevant
environments, the quantum correlations can persist even in the asymptotic
long-time regime.
|
[
{
"version": "v1",
"created": "Fri, 7 Jul 2006 08:24:12 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Benatti",
"F.",
""
],
[
"Floreanini",
"R.",
""
]
] |
quant-ph/0607050
|
Marko Znidaric
|
Thomas Gorin, Tomaz Prosen, Thomas H. Seligman and Marko Znidaric
|
Dynamics of Loschmidt echoes and fidelity decay
|
Review article with some original results in integrable systems and
random matrix models; 133 pages, 53 figures
|
Phys. Rep. 435, 33-156 (2006)
|
10.1016/j.physrep.2006.09.003
| null |
quant-ph
| null |
Fidelity serves as a benchmark for the relieability in quantum information
processes, and has recently atracted much interest as a measure of the
susceptibility of dynamics to perturbations. A rich variety of regimes for
fidelity decay have emerged. The purpose of the present review is to describe
these regimes, to give the theory that supports them, and to show some
important applications and experiments. While we mention several approaches we
use time correlation functions as a backbone for the discussion. Vanicek's
uniform approach to semiclassics and random matrix theory provides an important
alternative or complementary aspects. Other methods will be mentioned as we go
along. Recent experiments in micro-wave cavities and in elastodynamic systems
as well as suggestions for experiments in quantum optics shall be discussed.
|
[
{
"version": "v1",
"created": "Fri, 7 Jul 2006 09:42:44 GMT"
},
{
"version": "v2",
"created": "Thu, 14 Sep 2006 11:34:10 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Gorin",
"Thomas",
""
],
[
"Prosen",
"Tomaz",
""
],
[
"Seligman",
"Thomas H.",
""
],
[
"Znidaric",
"Marko",
""
]
] |
quant-ph/0607051
|
Alexander Holevo
|
A. S. Holevo
|
One-mode quantum Gaussian channels
|
12 pages, classification improved, typos corrected, reference added
|
Problems of Information Transmission, v.43, 1-11, 2007
| null | null |
quant-ph
| null |
A classification of one-mode Gaussian channels is given up to canonical
unitary equivalence. A complementary to the quantum channel with additive
classical Gaussian noise is described providing an example of one-mode Gaussian
channel which is neither degradable nor anti-degradable.
|
[
{
"version": "v1",
"created": "Fri, 7 Jul 2006 09:46:48 GMT"
},
{
"version": "v2",
"created": "Sun, 16 Jul 2006 18:00:51 GMT"
}
] | 2010-12-30T00:00:00 |
[
[
"Holevo",
"A. S.",
""
]
] |
quant-ph/0607052
|
Guido Zambra
|
G. Zambra and M. G. A. Paris
|
Reconstruction of photon statistics using low performance photon
counters
|
8 pages, 3 figures
|
Phys. Rev. A 74, 063830 (2006).
|
10.1103/PhysRevA.74.063830
| null |
quant-ph
| null |
The output of a photodetector consists of a current pulse whose charge has
the statistical distribution of the actual photon numbers convolved with a
Bernoulli distribution. Photodetectors are characterized by a nonunit quantum
efficiency, i.e. not all the photons lead to a charge, and by a finite
resolution, i.e. a different number of detected photons leads to a
discriminable values of the charge only up to a maximum value. We present a
detailed comparison, based on Monte Carlo simulated experiments and real data,
among the performances of detectors with different upper limits of counting
capability. In our scheme the inversion of Bernoulli convolution is performed
by maximum-likelihood methods assisted by measurements taken at different
quantum efficiencies. We show that detectors that are only able to discriminate
between zero, one and more than one detected photons are generally enough to
provide a reliable reconstruction of the photon statistics for single-peaked
distributions, while detectors with higher resolution limits do not lead to
further improvements. In addition, we demonstrate that, for semiclassical
states, even on/off detectors are enough to provide a good reconstruction.
Finally, we show that a reliable reconstruction of multi-peaked distributions
requires either higher quantum efficiency or better capability in
discriminating high number of detected photons.
|
[
{
"version": "v1",
"created": "Fri, 7 Jul 2006 11:22:31 GMT"
}
] | 2015-06-26T00:00:00 |
[
[
"Zambra",
"G.",
""
],
[
"Paris",
"M. G. A.",
""
]
] |
quant-ph/0607053
|
Ujjwal Sen
|
Sibylle Braungardt, Aditi Sen De, Ujjwal Sen, Maciej Lewenstein
|
Error-Resistant Distributed Quantum Computation in Trapped Ion Chain
|
10 pages, 7 figures, RevTeX4; v2: another noise model analysed,
published version
|
Phys. Rev. A 76, 042307 (2007)
|
10.1103/PhysRevA.76.042307
| null |
quant-ph cond-mat.dis-nn
| null |
We consider experimentally feasible chains of trapped ions with pseudo-spin
1/2, and find models that can potentially be used to implement error-resistant
quantum computation. Similar in spirit to classical neural networks, the
error-resistance of the system is achieved by encoding the qubits distributed
over the whole system. We therefore call our system a ''quantum neural
network'', and present a ''quantum neural network model of quantum
computation''. Qubits are encoded in a few quasi-degenerated low energy levels
of the whole system, separated by a large gap from the excited states, and
large energy barriers between themselves. We investigate protocols for
implementing a universal set of quantum logic gates in the system, by adiabatic
passage of a few low-lying energy levels of the whole system. Naturally
appearing and potentially dangerous distributed noise in the system leaves the
fidelity of the computation virtually unchanged, if it is not too strong. The
computation is also naturally resilient to local perturbations of the spins.
|
[
{
"version": "v1",
"created": "Fri, 7 Jul 2006 13:03:28 GMT"
},
{
"version": "v2",
"created": "Fri, 4 Jan 2008 16:22:42 GMT"
}
] | 2009-10-20T00:00:00 |
[
[
"Braungardt",
"Sibylle",
""
],
[
"De",
"Aditi Sen",
""
],
[
"Sen",
"Ujjwal",
""
],
[
"Lewenstein",
"Maciej",
""
]
] |
quant-ph/0607054
|
Thomas Coudreau
|
Thomas Coudreau (MPQ), Fr\'ed\'eric Grosshans (LPQM), Samuel Guibal
(MPQ), Luca Guidoni (MPQ)
|
Feasibility of a quantum memory for continuous variables based on
trapped ions
|
v2, typos corrected
| null | null | null |
quant-ph
| null |
We propose to use a large cloud of cold trapped ions as a medium for quantum
optics and quantum information experiments. Contrary to most recent
realizations of qubit manipulation based on a small number of trapped and
cooled ions, we study the case of traps containing a macroscopic number of
ions. We consider in particular the implementation of a quantum memory for
quantum information stored in continuous variables and study the impact of the
relevant physical parameters on the expected performances of the system.
|
[
{
"version": "v1",
"created": "Fri, 7 Jul 2006 13:20:23 GMT"
},
{
"version": "v2",
"created": "Sat, 8 Jul 2006 08:45:17 GMT"
}
] | 2016-08-16T00:00:00 |
[
[
"Coudreau",
"Thomas",
"",
"MPQ"
],
[
"Grosshans",
"Frédéric",
"",
"LPQM"
],
[
"Guibal",
"Samuel",
"",
"MPQ"
],
[
"Guidoni",
"Luca",
"",
"MPQ"
]
] |
quant-ph/0607055
|
John Chiaverini
|
K. Vant, J. Chiaverini, W. Lybarger, and D. J. Berkeland
|
Photoionization of strontium for trapped-ion quantum information
processing
|
7 pages, 3 figures, RevTeX4
| null | null |
LA-UR-06-4610
|
quant-ph
| null |
We report a demonstration of simple and effective loading of strontium ions
into a linear radio frequency Paul trap using photoionization. The ionization
pathway is 5s2 1S0 -- 5s5p 1P1 -- 5p2 1D2, and the 5p2 1D2 final state is
auto-ionizing. Both transitions are driven using diode lasers: a
grating-stabilized 922 nm diode doubled in a single pass through potassium
niobate to 461 nm and a bare diode at 405 nm. Using this technique, we have
reduced the background pressure during the ion loading process by a factor of 2
compared to the conventional technique of electron bombardment. Initial ion
temperatures are low enough that the ions immediately form crystals. It is also
possible to observe the trapping region with a CCD camera during ion creation,
allowing specific ion number loading with high probability.
|
[
{
"version": "v1",
"created": "Fri, 7 Jul 2006 16:23:01 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Vant",
"K.",
""
],
[
"Chiaverini",
"J.",
""
],
[
"Lybarger",
"W.",
""
],
[
"Berkeland",
"D. J.",
""
]
] |
quant-ph/0607056
|
Chi-Hang Fred Fung
|
Chi-Hang Fred Fung and Hoi-Kwong Lo
|
Security proof of a three-state quantum key distribution protocol
without rotational symmetry
|
10 pages, 3 figures, 2 columns
|
Physical Review A 74, 042342 (2006)
|
10.1103/PhysRevA.74.042342
| null |
quant-ph
| null |
Standard security proofs of quantum key distribution (QKD) protocols often
rely on symmetry arguments. In this paper, we prove the security of a
three-state protocol that does not possess rotational symmetry. The three-state
QKD protocol we consider involves three qubit states, where the first two
states, |0_z> and |1_z>, can contribute to key generation and the third state,
|+>=(|0_z>+|1_z>)/\sqrt{2}, is for channel estimation. This protocol has been
proposed and implemented experimentally in some frequency-based QKD systems
where the three states can be prepared easily. Thus, by founding on the
security of this three-state protocol, we prove that these QKD schemes are, in
fact, unconditionally secure against any attacks allowed by quantum mechanics.
The main task in our proof is to upper bound the phase error rate of the qubits
given the bit error rates observed. Unconditional security can then be proved
not only for the ideal case of a single-photon source and perfect detectors,
but also for the realistic case of a phase-randomized weak coherent light
source and imperfect threshold detectors. Our result on the phase error rate
upper bound is independent of the loss in the channel. Also, we compare the
three-state protocol with the BB84 protocol. For the single-photon source case,
our result proves that the BB84 protocol strictly tolerates a higher quantum
bit error rate than the three-state protocol; while for the coherent-source
case, the BB84 protocol achieves a higher key generation rate and secure
distance than the three-state protocol when a decoy-state method is used.
|
[
{
"version": "v1",
"created": "Sat, 8 Jul 2006 16:48:20 GMT"
},
{
"version": "v2",
"created": "Tue, 1 Aug 2006 13:57:25 GMT"
},
{
"version": "v3",
"created": "Wed, 20 Sep 2006 11:59:27 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Fung",
"Chi-Hang Fred",
""
],
[
"Lo",
"Hoi-Kwong",
""
]
] |
quant-ph/0607057
|
Travis Norsen
|
Travis Norsen
|
Against `Realism'
|
Revised version, forthcoming in Foundations of Physics
|
Foundations of Physics, Vol. 37 No. 3, 311-340 (March 2007)
|
10.1007/s10701-007-9104-1
| null |
quant-ph
| null |
We examine the prevalent use of the phrase ``local realism'' in the context
of Bell's Theorem and associated experiments, with a focus on the question:
what exactly is the `realism' in `local realism' supposed to mean? Carefully
surveying several possible meanings, we argue that all of them are flawed in
one way or another as attempts to point out a second premise (in addition to
locality) on which the Bell inequalities rest, and (hence) which might be
rejected in the face of empirical data violating the inequalities. We thus
suggest that the phrase `local realism' should be banned from future
discussions of these issues, and urge physicists to revisit the foundational
questions behind Bell's Theorem.
|
[
{
"version": "v1",
"created": "Fri, 7 Jul 2006 20:07:42 GMT"
},
{
"version": "v2",
"created": "Thu, 16 Nov 2006 16:14:50 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Norsen",
"Travis",
""
]
] |
quant-ph/0607058
|
Tao Qin
|
Meisheng Zhao, Tao Qin and Yongde Zhang
|
The fidelity of general bosonic channels with pure state input
|
3 pages, comments welcome
| null |
10.1142/S0217984907013808
| null |
quant-ph
| null |
We first derive for the general form of the fidelity for various bosonic
channels. Thereby we give the fidelity of different quantum bosonic channel,
possibly with product input and entangled input respectively, as examples. The
properties of the fidelity are carefully examined.
|
[
{
"version": "v1",
"created": "Sat, 8 Jul 2006 08:34:21 GMT"
},
{
"version": "v2",
"created": "Fri, 19 Jan 2007 23:46:05 GMT"
},
{
"version": "v3",
"created": "Tue, 23 Jan 2007 11:54:12 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Zhao",
"Meisheng",
""
],
[
"Qin",
"Tao",
""
],
[
"Zhang",
"Yongde",
""
]
] |
quant-ph/0607059
|
Cosmo Lupo
|
C. Lupo, V. I. Man'ko, G. Marmo
|
Bell's inequalities in the tomographic representation
|
11 pages, comments and references added
|
J.Phys. A39 (2006) 12515-12524
|
10.1088/0305-4470/39/40/016
| null |
quant-ph
| null |
The tomographic approach to quantum mechanics is revisited as a direct tool
to investigate violation of Bell-like inequalities. Since quantum tomograms are
well defined probability distributions, the tomographic approach is emphasized
to be the most natural one to compare the predictions of classical and quantum
theory. Examples of inequalities for two qubits an two qutrits are considered
in the tomographic probability representation of spin states.
|
[
{
"version": "v1",
"created": "Sat, 8 Jul 2006 13:44:36 GMT"
},
{
"version": "v2",
"created": "Fri, 22 Sep 2006 13:46:53 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Lupo",
"C.",
""
],
[
"Man'ko",
"V. I.",
""
],
[
"Marmo",
"G.",
""
]
] |
quant-ph/0607060
|
Sebastien Louis Mr
|
Sebastien G.R. Louis, Kae Nemoto, W.J. Munro and T.P. Spiller
|
The efficiencies of generating cluster states with weak non-linearities
|
21 pages, to appear in special issue of New J. Phys. on
"Measurement-Based Quantum Information Processing"
|
New J. Phys. 9, 193 (2007)
|
10.1088/1367-2630/9/6/193
| null |
quant-ph
| null |
We propose a scalable approach to building cluster states of matter qubits
using coherent states of light. Recent work on the subject relies on the use of
single photonic qubits in the measurement process. These schemes can be made
robust to detector loss, spontaneous emission and cavity mismatching but as a
consequence the overhead costs grow rapidly, in particular when considering
single photon loss. In contrast, our approach uses continuous variables and
highly efficient homodyne measurements. We present a two-qubit scheme, with a
simple bucket measurement system yielding an entangling operation with success
probability 1/2. Then we extend this to a three-qubit interaction, increasing
this probability to 3/4. We discuss the important issues of the overhead cost
and the time scaling. This leads to a "no-measurement" approach to building
cluster states, making use of geometric phases in phase space.
|
[
{
"version": "v1",
"created": "Mon, 10 Jul 2006 13:10:22 GMT"
},
{
"version": "v2",
"created": "Mon, 16 Apr 2007 02:18:50 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Louis",
"Sebastien G. R.",
""
],
[
"Nemoto",
"Kae",
""
],
[
"Munro",
"W. J.",
""
],
[
"Spiller",
"T. P.",
""
]
] |
quant-ph/0607061
|
Caterina-Eloisa Mora
|
M. Piani, C. Mora
|
Class of PPT bound entangled states associated to almost any set of pure
entangled states
|
12 pages, 3 figures. To appear in Phys. Rev. A
|
Phys. Rev. A 75, 012305 (2007)
|
10.1103/PhysRevA.75.012305
| null |
quant-ph
| null |
We analyze a class of entangled states for bipartite $d \otimes d$ systems,
with $d$ non-prime. The entanglement of such states is revealed by the
construction of canonically associated entanglement witnesses. The structure of
the states is very simple and similar to the one of isotropic states: they are
a mixture of a separable and a pure entangled state whose supports are
orthogonal. Despite such simple structure, in an opportune interval of the
mixing parameter their entanglement is not revealed by partial transposition
nor by the realignment criterion, i.e. by any permutational criterion in the
bipartite setting. In the range in which the states are Positive under Partial
Transposition (PPT), they are not distillable; on the other hand, the states in
the considered class are provably distillable as soon as they are Nonpositive
under Partial Transposition (NPT). The states are associated to any set of more
than two pure states. The analysis is extended to the multipartite setting. By
an opportune selection of the set of multipartite pure states, it is possible
to construct mixed states which are PPT with respect to any choice of bipartite
cuts and nevertheless exhibit genuine multipartite entanglement. Finally, we
show that every $k$-positive but not completely positive map is associated to a
family of nondecomposable maps.
|
[
{
"version": "v1",
"created": "Mon, 10 Jul 2006 13:50:16 GMT"
},
{
"version": "v2",
"created": "Mon, 13 Nov 2006 18:05:35 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Piani",
"M.",
""
],
[
"Mora",
"C.",
""
]
] |
quant-ph/0607062
|
Tomasz Paterek
|
Tomasz Paterek
|
Measurements on Composite Qudits
|
10 pages, 2 figures. Published version
|
Phys. Lett. A 367, 57 (2007)
|
10.1016/j.physleta.2007.05.082
| null |
quant-ph
| null |
We study measurements of the unitary generalization of Pauli operators.
First, an analytical (constructive) solution to the eigenproblem of these
operators is presented. Next, in the case of two subsystems, the Schmidt form
of the eigenvectors is derived to identify measurements which are easy to
implement. These results are utilized to show that quantum cryptography with
two bases, when operating on a two-component qudit, can be realized with
measurements on individual subsystems, assisted with classical communication.
We also discuss feasible devices which perform tomography of polarisation-path
qudits.
|
[
{
"version": "v1",
"created": "Mon, 10 Jul 2006 16:15:33 GMT"
},
{
"version": "v2",
"created": "Fri, 24 Aug 2007 10:18:17 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Paterek",
"Tomasz",
""
]
] |
quant-ph/0607063
|
Richard A. Mould
|
Richard A Mould
|
A Foundation Theory of Quantum Mechanics
|
22 pages, 4 figures,Trieste/Losinj Conference, 5-9 Sept. 2005
| null |
10.1063/1.2219367
| null |
quant-ph
| null |
The nRules are empirical regularities that were discovered in macroscopic
situations where the outcome is known. When they are projected theoretically
into the microscopic domain they predict a novel ontology including the
frequent collapse of an atomic wave function, thereby defining an nRule based
foundation theory. Future experiments can potentially discriminate between this
and other foundation theories of (non-relativistic) quantum mechanics.
Important features of the nRules are: (1) they introduce probability through
probability current rather than the Born rule, (2) they are valid independent
of size (micro or macroscopic), (3) they apply to individual trials, not just
to ensembles of trials. (4) they allow all observers to be continuously
included in the system without ambiguity, (5) they account for the collapse of
the wave function without introducing new or using old physical constants, and
(6) in dense environments they provide a high frequency of stochastic
localizations of quantum mechanical objects. Key words: measurement, stochastic
choice, state reduction.
|
[
{
"version": "v1",
"created": "Mon, 10 Jul 2006 17:28:32 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Mould",
"Richard A",
""
]
] |
quant-ph/0607064
|
Bernhard Breid
|
B. M. Breid, D. Witthaut and H. J. Korsch
|
Manipulation of matter waves using Bloch and Bloch-Zener oscillations
| null |
New J. Phys. 9 (2007) 62
|
10.1088/1367-2630/9/3/062
| null |
quant-ph
| null |
We present theoretical and numerical results on the dynamics of ultracold
atoms in an accelerated single- and double-periodic optical lattice. In the
single-periodic potential Bloch oscillations can be used to generate fast
directed transport with very little dispersion. The dynamics in the
double-periodic system is dominated by Bloch-Zener oscillations, i.e. the
interplay of Bloch oscillations and Zener tunneling between the subbands. Apart
from directed transport, the latter system permits various interesting
applications, such as widely tunable matter wave beam splitters and
Mach-Zehnder interferometry. As an application, a method for efficient probing
of small nonlinear mean-field interactions is suggested.
|
[
{
"version": "v1",
"created": "Mon, 10 Jul 2006 18:46:31 GMT"
}
] | 2008-08-12T00:00:00 |
[
[
"Breid",
"B. M.",
""
],
[
"Witthaut",
"D.",
""
],
[
"Korsch",
"H. J.",
""
]
] |
quant-ph/0607065
|
Rodney Van Meter
|
Rodney Doyle Van Meter III
|
Architecture of a Quantum Multicomputer Optimized for Shor's Factoring
Algorithm
|
Ph.D. thesis, Keio University: 256 pages, 57 figures and 60,000+
words in 103 files. Get the PDF file if you can, the PostScript is big
| null | null | null |
quant-ph
| null |
The quantum multicomputer consists of a large number of small nodes and a
qubus interconnect for creating entangled state between the nodes. The primary
metric chosen is the performance of such a system on Shor's algorithm for
factoring large numbers: specifically, the quantum modular exponentiation step
that is the computational bottleneck. This dissertation introduces a number of
optimizations for the modular exponentiation. My algorithms reduce the latency,
or circuit depth, to complete the modular exponentiation of an n-bit number
from O(n^3) to O(n log^2 n) or O(n^2 log n), depending on architecture.
Calculations show that these algorithms are one million times and thirteen
thousand times faster, when factoring a 6,000-bit number, depending on
architecture. Extending to the quantum multicomputer, five different qubus
interconnect topologies are considered, and two forms of carry-ripple adder are
found to be the fastest for a wide range of performance parameters. The links
in the quantum multicomputer are serial; parallel links would provide only very
modest improvements in system reliability and performance. Two levels of the
Steane [[23,1,7]] error correction code will adequately protect our data for
factoring a 1,024-bit number even when the qubit teleportation failure rate is
one percent.
|
[
{
"version": "v1",
"created": "Tue, 11 Jul 2006 06:26:36 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Meter",
"Rodney Doyle Van",
"III"
]
] |
quant-ph/0607066
|
Cem Y
|
C. Yuce
|
Free electron in a laser field: The nonrelativistic solution
| null |
Phys. Rev. A 74, 062106 (2006)
|
10.1103/PhysRevA.74.062106
| null |
quant-ph
| null |
Schrodinger equation for a charged particle interacting with the plane wave
electromagnetic field is solved exactly. The exact analytic solution and the
perturbative solution up to second order are compared.
|
[
{
"version": "v1",
"created": "Tue, 11 Jul 2006 06:47:37 GMT"
},
{
"version": "v2",
"created": "Wed, 18 Oct 2006 08:23:16 GMT"
},
{
"version": "v3",
"created": "Thu, 30 Nov 2006 09:31:03 GMT"
},
{
"version": "v4",
"created": "Mon, 11 Dec 2006 12:40:16 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Yuce",
"C.",
""
]
] |
quant-ph/0607067
|
Satyabrata Adhikari
|
Satyabrata Adhikari, B.S.Choudhury
|
Broadcasting of three qubit entanglement via local copying and
entanglement swapping
|
18 pages, 4 figures, Accepted in Physical Review A
|
Phys. Rev. A 74, 032323 (2006)
|
10.1103/PhysRevA.74.032323
| null |
quant-ph
| null |
In this work,We investigate the problem of secretly broadcasting of
three-qubit entangled state between two distant partners. The interesting
feature of this problem is that starting from two particle entangled state
shared between two distant partners we find that the action of local cloner on
the qubits and the measurement on the machine state vector generates
three-qubit entanglement between them. The broadcasting of entanglement is made
secret by sending the measurement result secretly using cryptographic scheme
based on orthogonal states. Further we show that this idea can be extended to
generate three particle entangled state between three distant partners.
|
[
{
"version": "v1",
"created": "Tue, 11 Jul 2006 07:56:52 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Adhikari",
"Satyabrata",
""
],
[
"Choudhury",
"B. S.",
""
]
] |
quant-ph/0607068
|
Sylvain Gigan
|
S. Gigan, H. R. Boehm, M. Paternostro, F. Blaser, G. Langer, J. B.
Hertzberg, K. Schwab, D. Baeuerle, M. Aspelmeyer, A. Zeilinger
|
Self-cooling of a micro-mirror by radiation pressure
|
11 pages, 9 figures, minor corrections
|
Nature 444, 67 - 70 (02 Nov 2006)
|
10.1038/nature05273
| null |
quant-ph cond-mat.mtrl-sci
| null |
We demonstrate passive feedback cooling of a mechanical resonator based on
radiation pressure forces and assisted by photothermal forces in a high-finesse
optical cavity. The resonator is a free-standing high-reflectance micro-mirror
(of mass m=400ng and mechanical quality factor Q=10^4) that is used as
back-mirror in a detuned Fabry-Perot cavity of optical finesse F=500. We
observe an increased damping in the dynamics of the mechanical oscillator by a
factor of 30 and a corresponding cooling of the oscillator modes below 10 K
starting from room temperature. This effect is an important ingredient for
recently proposed schemes to prepare quantum entanglement of macroscopic
mechanical oscillators.
|
[
{
"version": "v1",
"created": "Tue, 11 Jul 2006 09:54:34 GMT"
},
{
"version": "v2",
"created": "Wed, 8 Nov 2006 14:20:22 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Gigan",
"S.",
""
],
[
"Boehm",
"H. R.",
""
],
[
"Paternostro",
"M.",
""
],
[
"Blaser",
"F.",
""
],
[
"Langer",
"G.",
""
],
[
"Hertzberg",
"J. B.",
""
],
[
"Schwab",
"K.",
""
],
[
"Baeuerle",
"D.",
""
],
[
"Aspelmeyer",
"M.",
""
],
[
"Zeilinger",
"A.",
""
]
] |
quant-ph/0607069
|
Libby Heaney
|
L. Heaney, J. Anders, V. Vedral
|
Spatial Entanglement of a Free Bosonic Field
|
5 pages, 4 figures, extended version of the paper from 5 to 8 pages.
We have included a more detailed discussion and added new results that
support our original conclusions
| null | null | null |
quant-ph
| null |
In this paper we discuss the entanglement properties of a thermal
non-relativistic free bosonic field. We demonstrate how to formally construct
spatial modes in order to use a continuous variable separability criterion and
show that the construction of the modes plays a significant role in the way the
entanglement manifests itself. For instance the presence of entanglement
depends on the shape of the modes and their separation. The temperature of the
gas is another crucial factor and for one choice of modes we show that
entanglement can be found at arbitrarily high temperatures as long as we can
zoom in on suitably small regions in space. Moreover, we show that the
entanglement here is useful as it can be extracted to a pair of localised
systems.
|
[
{
"version": "v1",
"created": "Tue, 11 Jul 2006 10:29:53 GMT"
},
{
"version": "v2",
"created": "Tue, 25 Jul 2006 12:45:16 GMT"
},
{
"version": "v3",
"created": "Fri, 1 Jun 2007 13:33:17 GMT"
}
] | 2007-06-13T00:00:00 |
[
[
"Heaney",
"L.",
""
],
[
"Anders",
"J.",
""
],
[
"Vedral",
"V.",
""
]
] |
quant-ph/0607070
|
Michael M. Wolf
|
Michael M. Wolf, David Perez-Garcia
|
Quantum Capacities of Channels with small Environment
| null |
Phys. Rev. A 75, 012303 (2007)
|
10.1103/PhysRevA.75.012303
| null |
quant-ph
| null |
We investigate the quantum capacity of noisy quantum channels which can be
represented by coupling a system to an effectively small environment. A
capacity formula is derived for all cases where both system and environment are
two-dimensional--including all extremal qubit channels. Similarly, for channels
acting on higher dimensional systems we show that the capacity can be
determined if the channel arises from a sufficiently small coupling to a qubit
environment. Extensions to instances of channels with larger environment are
provided and it is shown that bounds on the capacity with unconstrained
environment can be obtained from decompositions into channels with small
environment.
|
[
{
"version": "v1",
"created": "Tue, 11 Jul 2006 11:46:02 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Wolf",
"Michael M.",
""
],
[
"Perez-Garcia",
"David",
""
]
] |
quant-ph/0607071
|
Roberto Floreanini
|
F. Benatti and R. Floreanini
|
Tests of Complete Positivity in Fiber Optics
|
10 pages, LaTeX
| null | null | null |
quant-ph cond-mat.other hep-th
| null |
We consider the propagation of polarized photons in optical fibers under the
action of randomly generated noise. In such situation, the change in time of
the photon polarization can be described by a quantum dynamical semigroup. We
show that the hierarchy among the decay constants of the polarization density
matrix elements as prescribed by complete positivity can be experimentally
probed using standard laboratory set-ups.
|
[
{
"version": "v1",
"created": "Tue, 11 Jul 2006 12:53:43 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Benatti",
"F.",
""
],
[
"Floreanini",
"R.",
""
]
] |
quant-ph/0607072
|
Artem Dudarev
|
A.M. Dudarev, M.G. Raizen, Qian Niu
|
Quantum Many-Body Culling
| null | null | null | null |
quant-ph
| null |
We propose a method to produce a definite number of ground-state atoms by
adiabatic reduction of the depth of a potential well that confines a degenerate
Bose gas with repulsive interactions. Using a variety of methods, we map out
the maximum number of particles that can be supported by the well as a function
of the well depth and interaction strength, covering the limiting case of a
Tonks gas as well as the mean-field regime. We also estimate the time scales
for adiabaticity and discuss the recent observation of atomic number squeezing
(Chuu et al., Phys. Rev. Lett. {\bf 95}, 260403 (2005)).
|
[
{
"version": "v1",
"created": "Tue, 11 Jul 2006 14:23:19 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Dudarev",
"A. M.",
""
],
[
"Raizen",
"M. G.",
""
],
[
"Niu",
"Qian",
""
]
] |
quant-ph/0607073
|
Ferenc Sz\"oll\H{o}si
|
M\'at\'e Matolcsi, J\'ulia R\'effy and Ferenc Sz\"oll\H{o}si
|
Constructions of complex Hadamard matrices via tiling Abelian groups
|
15 pages
| null | null | null |
quant-ph
| null |
Applications in quantum information theory and quantum tomography have raised
current interest in complex Hadamard matrices. In this note we investigate the
connection between tiling Abelian groups and constructions of complex Hadamard
matrices. First, we recover a recent very general construction of complex
Hadamard matrices due to Dita via a natural tiling construction. Then we find
some necessary conditions for any given complex Hadamard matrix to be
equivalent to a Dita-type matrix. Finally, using another tiling construction,
due to Szabo, we arrive at new parametric families of complex Hadamard matrices
of order 8, 12 and 16, and we use our necessary conditions to prove that these
families do not arise with Dita's construction. These new families complement
the recent catalogue of complex Hadamard matrices of small order.
|
[
{
"version": "v1",
"created": "Tue, 11 Jul 2006 18:25:30 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Oct 2006 09:54:33 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Matolcsi",
"Máté",
""
],
[
"Réffy",
"Júlia",
""
],
[
"Szöllősi",
"Ferenc",
""
]
] |
quant-ph/0607074
|
Simone Severini
|
Toufik Mansour, Matthias Schork and Simone Severini
|
Noncrossing normal ordering for functions of boson operators
|
16 pages, 10 figures
| null |
10.1007/s10773-007-9508-x
| null |
quant-ph math-ph math.CO math.MP
| null |
Normally ordered forms of functions of boson operators are important in many
contexts in particular concerning Quantum Field Theory and Quantum Optics.
Beginning with the seminal work of Katriel [Lett. Nuovo Cimento,
10(13):565--567, 1974], in the last few years, normally ordered forms have been
shown to have a rich combinatorial structure, mainly in virtue of a link with
the theory of partitions. In this paper, we attempt to enrich this link. By
considering linear representations of noncrossing partitions, we define the
notion of noncrossing normal ordering. Given the growing interest in
noncrossing partitions, because of their many unexpected connections (like, for
example, with free probability), noncrossing normal ordering appears to be an
intriguing notion. We explicitly give the noncrossing normally ordered form of
the functions (a^{r}(a^{\dag})^{s})^{n}) and (a^{r}+(a^{\dag})^{s})^{n}, plus
various special cases. We are able to establish for the first time bijections
between noncrossing contractions of these functions, k-ary trees and sets of
lattice paths.
|
[
{
"version": "v1",
"created": "Tue, 11 Jul 2006 21:54:16 GMT"
},
{
"version": "v2",
"created": "Tue, 3 Apr 2007 00:51:31 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Mansour",
"Toufik",
""
],
[
"Schork",
"Matthias",
""
],
[
"Severini",
"Simone",
""
]
] |
quant-ph/0607075
|
Wei-Qin Zhao
|
R. Friedberg, T. D. Lee and W. Q. Zhao
|
Iterative Solutions for Low Lying Excited States of a Class of
Schroedinger Equation
|
14 pages, 4 figures
| null |
10.1088/1009-1963/15/9/001
| null |
quant-ph
| null |
The convergent iterative procedure for solving the groundstate Schroedinger
equation is extended to derive the excitation energy and the wave function of
the low-lying excited states. The method is applied to the one-dimensional
quartic potential problem. The results show that the iterative solution
converges rapidly when the coupling $g$ is not too small.
|
[
{
"version": "v1",
"created": "Wed, 12 Jul 2006 01:41:53 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Friedberg",
"R.",
""
],
[
"Lee",
"T. D.",
""
],
[
"Zhao",
"W. Q.",
""
]
] |
quant-ph/0607076
|
Vladimir Privman
|
Vladimir Privman, Dmitry Solenov, Denis Tolkunov
|
Onset of Entanglement and Noise Cross-Correlations in Two-Qubit System
Interacting with Common Bosonic Bath
|
4 pages in LaTeX, with EPS figures
|
Proc. Conf. ICSICT-2006, Part 2, Pages 1054-1057, edited by T.-A.
Tang, G.-P. Ru and Y.-L. Jiang (IEEE Press, Piscataway, NJ, 2006)
|
10.1109/ICSICT.2006.306659
| null |
quant-ph
| null |
We summarize our recent results for the induced exchange interaction due to
thermal bosonic environment (bath) which also generates quantum noise. Our
focus here is on the onset of the interaction. We demonstrate that the induced
interaction can be used to manipulate and create entanglement over time scales
sufficiently large for controlling the two-qubit system for quantum computing
applications, though ultimately the noise effects will dominate.
|
[
{
"version": "v1",
"created": "Wed, 12 Jul 2006 04:10:09 GMT"
}
] | 2010-09-22T00:00:00 |
[
[
"Privman",
"Vladimir",
""
],
[
"Solenov",
"Dmitry",
""
],
[
"Tolkunov",
"Denis",
""
]
] |
quant-ph/0607077
|
Rustem Shakhmuratov
|
R. N. Shakhmuratov, J. Odeurs, and Paul Mandel
|
A single photon emitted by a single particle in free space vacuum modes
and its resonant interaction with two- and three-level absorbers
|
28 pages, 7 figures
| null |
10.1103/PhysRevA.75.013808
| null |
quant-ph
| null |
We consider the time-delayed coincidence counting of two photons emitted in a
cascade by a single particle (atom, molecule, nucleus, etc). The
time-dependence of the probability amplitude of the second photon in the
cascade has a sharply rising leading edge due to the detection of the first
photon, as results from causality. If a macroscopic ensemble of resonant
two-level absorbers is placed in the path of the second photon between the
radiation source and the detector, the photon absorption does not follow Beer's
law due to the time-asymmetric shape of the photon. For very short delay times
almost no absorption takes place, even in an optically dense medium. We analyze
the propagation of such a second photon in a thick resonant three-level
absorber if a narrow electromagnetically induced transparency (EIT) window is
present at the center of the absorption line. It is shown that the EIT medium
can change the asymmetric time dependence of the photon probability amplitude
to a bell shape (EIT filtering). This bell-shaped photon interacts much more
efficiently with an other ensemble of two-level absorbers chosen, for example,
to store this photon and the information it carries.
|
[
{
"version": "v1",
"created": "Wed, 12 Jul 2006 10:38:20 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Shakhmuratov",
"R. N.",
""
],
[
"Odeurs",
"J.",
""
],
[
"Mandel",
"Paul",
""
]
] |
quant-ph/0607078
|
Archan S. Majumdar
|
Biplab Ghosh, A. S. Majumdar, N. Nayak
|
Environment assisted entanglement enhancement
|
4 pages, Revtex, 1 eps figure; minor changes to match with published
version
|
Phys. Rev. A 74, 052315 (2006)
|
10.1103/PhysRevA.74.052315
| null |
quant-ph
| null |
We consider dissipative atom-cavity systems and show that their collective
dynamics leads to the maximization of entanglement for intermediate values of
the cavity leakage parameter $\kappa$. We discuss possible ways the reservoir
influences entanglement. We first consider the entanglement of a single
two-level atom with a microwave cavity that is coupled to another cavity. We
show that the atom-cavity entanglement can be made to increase with cavity
leakage. We next show that the entanglement between two atoms passing
successively through a cavity can be maximised for intermediate values of
$\kappa$. We finally consider the micromaser where the increase of two-atom
entanglement for stronger cavity-environment coupling is demonstrated for
experimentally attainable values of the micromaser parameters.
|
[
{
"version": "v1",
"created": "Wed, 12 Jul 2006 12:01:44 GMT"
},
{
"version": "v2",
"created": "Fri, 22 Dec 2006 09:30:27 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Ghosh",
"Biplab",
""
],
[
"Majumdar",
"A. S.",
""
],
[
"Nayak",
"N.",
""
]
] |
quant-ph/0607079
|
Adolfo del Campo
|
A. del Campo, J. G. Muga
|
Exact propagators for atom-laser interactions
|
13 pages, 6 figures
|
J. Phys. A, 39, 14079 (2006) (extended)
|
10.1088/0305-4470/39/45/017
| null |
quant-ph cond-mat.other math-ph math.MP
| null |
A class of exact propagators describing the interaction of an $N$-level atom
with a set of on-resonance $\delta$-lasers is obtained by means of the Laplace
transform method. State-selective mirrors are described in the limit of strong
lasers. The ladder, V and $\Lambda$ configurations for a three-level atom are
discussed. For the two level case, the transient effects arising as result of
the interaction between both a semi-infinite beam and a wavepacket with the
on-resonance laser are examined.
|
[
{
"version": "v1",
"created": "Thu, 13 Jul 2006 08:14:20 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"del Campo",
"A.",
""
],
[
"Muga",
"J. G.",
""
]
] |
quant-ph/0607080
|
Oliver Gloeckl
|
O. Gl\"ockl, U. L. Andersen, R. Filip, W. P. Bowen, G. Leuchs
|
Squeezed state purification with linear optics and feed forward
|
4 pages, 3 figures
|
Phys. Rev. Lett. 97, 053601 (2006)
|
10.1103/PhysRevLett.97.053601
| null |
quant-ph
| null |
A scheme for optimal and deterministic linear optical purification of mixed
squeezed Gaussian states is proposed and experimentally demonstrated. The
scheme requires only linear optical elements and homodyne detectors, and allows
the balance between purification efficacy and squeezing degradation to be
controlled. One particular choice of parameters gave a ten-fold reduction of
the thermal noise with a corresponding squeezing degradation of only 11%. We
prove optimality of the protocol, and show that it can be used to enhance the
performance of quantum informational protocols such as dense coding and
entanglement generation.
|
[
{
"version": "v1",
"created": "Thu, 13 Jul 2006 11:15:03 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Glöckl",
"O.",
""
],
[
"Andersen",
"U. L.",
""
],
[
"Filip",
"R.",
""
],
[
"Bowen",
"W. P.",
""
],
[
"Leuchs",
"G.",
""
]
] |
quant-ph/0607081
|
Ingunn Kathrine Wehus
|
H. Alnes, K. Olaussen, F. Ravndal and I. K. Wehus
|
Electromagnetic Casimir energy with extra dimensions
|
16 pages, typos corrected, published version
|
Phys.Rev.D74:105017,2006
|
10.1103/PhysRevD.74.105017
| null |
quant-ph hep-ph hep-th
| null |
We calculate the energy-momentum tensor due to electromagnetic vacuum
fluctuations between two parallel hyperplanes in more than four dimensions,
considering both metallic and MIT boundary conditions. Using the axial gauge,
the problem can be mapped upon the corresponding problem with a massless,
scalar field satisfying respectively Dirichlet or Neumann boundary conditions.
The pressure between the plates is constant while the energy density is found
to diverge at the boundaries when there are extra dimensions. This can be
related to the fact that Maxwell theory is then no longer conformally
invariant. A similar behavior is known for the scalar field where a constant
energy density consistent with the pressure can be obtained by improving the
energy-momentum tensor with the Huggins term. This is not possible for the
Maxwell field. However, the change in the energy-momentum tensor with distance
between boundaries is finite in all cases.
|
[
{
"version": "v1",
"created": "Thu, 13 Jul 2006 11:35:19 GMT"
},
{
"version": "v2",
"created": "Fri, 6 Oct 2006 17:45:33 GMT"
},
{
"version": "v3",
"created": "Fri, 6 Jul 2007 23:58:35 GMT"
}
] | 2008-11-26T00:00:00 |
[
[
"Alnes",
"H.",
""
],
[
"Olaussen",
"K.",
""
],
[
"Ravndal",
"F.",
""
],
[
"Wehus",
"I. K.",
""
]
] |
quant-ph/0607082
|
Kiyoshi Tamaki
|
Kiyoshi Tamaki, Norbert L\"utkenhaus, Masato Koashi, Jamie
Batuwantudawe
|
Unconditional security of the Bennett 1992 quantum key-distribution
scheme with strong reference pulse
|
More detailed presentation and a bit modified security proof
|
Phys. Rev. A 80 032302 (2009)
|
10.1103/PhysRevA.80.032302
| null |
quant-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We prove the unconditional security of the original Bennett 1992 protocol
with strong reference pulse. We show that we may place a projection onto
suitably defined qubit spaces before the receiver, which makes the analysis as
simple as qubit-based protocols. Unlike the single-photon-based qubits, the
qubits identified in this scheme are almost surely detected by the receiver
even after a lossy channel. This leads to the key generation rate that is
proportional to the channel transmission rate for proper choices of
experimental parameters.
|
[
{
"version": "v1",
"created": "Thu, 13 Jul 2006 12:56:19 GMT"
},
{
"version": "v2",
"created": "Thu, 3 Sep 2009 02:48:22 GMT"
}
] | 2013-05-29T00:00:00 |
[
[
"Tamaki",
"Kiyoshi",
""
],
[
"Lütkenhaus",
"Norbert",
""
],
[
"Koashi",
"Masato",
""
],
[
"Batuwantudawe",
"Jamie",
""
]
] |
quant-ph/0607083
|
Todd Pittman
|
T.B. Pittman and J.D. Franson
|
Generation of Entangled Photon Holes using Quantum Interference
|
4 pages, color figures, submitted to Phys. Rev. A
|
Phys. Rev. A 74, 041801R (2006)
|
10.1103/PhysRevA.74.041801
| null |
quant-ph
| null |
In addition to photon pairs entangled in polarization or other variables,
quantum mechanics also allows optical beams that are entangled through the
absence of the photons themselves. These correlated absences, or ``entangled
photon holes'', can lead to counter-intuitive nonlocal effects analogous to
those of the more familiar entangled photon pairs. Here we report an
experimental observation of photon holes generated using quantum interference
effects to suppress the probability that two photons in a weak laser pulse will
separate at an optical beam splitter.
|
[
{
"version": "v1",
"created": "Thu, 13 Jul 2006 14:48:59 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Pittman",
"T. B.",
""
],
[
"Franson",
"J. D.",
""
]
] |
quant-ph/0607084
|
Rafa{\l} Demkowicz-Dobrza\'nski
|
Rafal Demkowicz-Dobrzanski, Andreas Buchleitner, Marek Kus, Florian
Mintert
|
Evaluable multipartite entanglement measures: are multipartite
concurrences entanglement monotones?
|
7 pages, 1 figure, minor changes - clarity of proofs improved
|
Phys. Rev. A 74, 052303 (2006)
|
10.1103/PhysRevA.74.052303
| null |
quant-ph
| null |
We discuss the monotonicity under local operations and classical
communication (LOCC) of systematically constructed quantities aiming at
quantification of entanglement properties of multipartite quantum systems. The
so-called generalized multipartite concurrences can qualify as legitimate
entanglement measures if they are monotonous under LOCC. In the paper we give a
necessary and sufficient criterion for their monotonicity.
|
[
{
"version": "v1",
"created": "Thu, 13 Jul 2006 18:33:05 GMT"
},
{
"version": "v2",
"created": "Fri, 4 Aug 2006 07:48:58 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Demkowicz-Dobrzanski",
"Rafal",
""
],
[
"Buchleitner",
"Andreas",
""
],
[
"Kus",
"Marek",
""
],
[
"Mintert",
"Florian",
""
]
] |
quant-ph/0607085
|
Klaus Hornberger
|
Klaus Hornberger
|
Master equation for a quantum particle in a gas
|
5 pages; published version
|
Phys. Rev. Lett. 97, 060601 (2006)
|
10.1103/PhysRevLett.97.060601
| null |
quant-ph
| null |
The equation for the quantum motion of a Brownian particle in a gaseous
environment is derived by means of S-matrix theory. This quantum version of the
linear Boltzmann equation accounts non-perturbatively for the quantum effects
of the scattering dynamics and describes decoherence and dissipation in a
unified framework. As a completely positive master equation it incorporates
both the known equation for an infinitely massive Brownian particle and the
classical linear Boltzmann equation as limiting cases.
|
[
{
"version": "v1",
"created": "Thu, 13 Jul 2006 20:01:16 GMT"
},
{
"version": "v2",
"created": "Tue, 5 Sep 2006 20:00:26 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Hornberger",
"Klaus",
""
]
] |
quant-ph/0607086
|
Daniel A. Lidar
|
Kaveh Khodjasteh and Daniel A. Lidar (USC)
|
Performance of Deterministic Dynamical Decoupling Schemes: Concatenated
and Periodic Pulse Sequences
|
17 pages, including 2 figures. v2: added a section on decoupling
spins in GaAs quantum dots, and some other improvements and additions
|
Phys. Rev. A. 75, 062310 (2007)
|
10.1103/PhysRevA.75.062310
| null |
quant-ph
| null |
Dynamical decoupling can be used to preserve arbitrary quantum states despite
undesired interactions with the environment, using control Hamiltonians
affecting the system only. We present a system-independent analysis of
dynamical decoupling based on leading order decoupling error estimates, valid
for bounded-strength environments. Using as a key tool a renormalization
transformation of the effective system-bath coupling Hamiltonian, we delineate
the reliability domain of dynamical decoupling used for quantum state
preservation, in a general setting for a single qubit. We specifically analyze
and compare two deterministic dynamical decoupling schemes -- periodic and
concatenated -- and distinguish between two limiting cases of fast versus slow
environments. We prove that concatenated decoupling outperforms periodic
decoupling over a wide range of parameters. These results are obtained for both
``ideal'' (zero-width) and realistic (finite-width) pulses This work extends
and generalizes our earlier work, Phys. Rev. Lett. 95, 180501 (2005).
|
[
{
"version": "v1",
"created": "Thu, 13 Jul 2006 20:42:16 GMT"
},
{
"version": "v2",
"created": "Thu, 15 Mar 2007 05:03:02 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Khodjasteh",
"Kaveh",
"",
"USC"
],
[
"Lidar",
"Daniel A.",
"",
"USC"
]
] |
quant-ph/0607087
|
Paulina Marian
|
Paulina Marian and Tudor A. Marian
|
Continuous-variable teleportation in the characteristic-function
description
|
12 pages
|
Physical Review A 74, 042306 (2006)
|
10.1103/PhysRevA.74.042306
| null |
quant-ph
| null |
We give a description of the continuous-variable teleportation protocol in
terms of the characteristic functions of the quantum states involved. The
Braunstein--Kimble protocol is written for an unbalanced homodyne measurement
and arbitrary input and resource states. We show that the output of the
protocol is a superposition between the input one-mode field and a classical
one induced by measurement and classical communication. We choose to describe
the input state distortion through teleportation by the average photon number
of the measurement-induced field. Only in the case of symmetric resource states
we find a relation between the optimal added noise and the minimal EPR
correlations used to define inseparability.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 00:09:49 GMT"
},
{
"version": "v2",
"created": "Tue, 26 Sep 2006 09:23:25 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Marian",
"Paulina",
""
],
[
"Marian",
"Tudor A.",
""
]
] |
quant-ph/0607088
|
Gabriel A. Durkin
|
Gabriel A. Durkin and Jonathan P. Dowling
|
Local and Global Distinguishability in Quantum Interferometry
|
4 pages, in submission, minor revisions
| null |
10.1103/PhysRevLett.99.070801
| null |
quant-ph
| null |
A statistical distinguishability based on relative entropy characterises the
fitness of quantum states for phase estimation. This criterion is employed in
the context of a Mach-Zehnder interferometer and used to interpolate between
two regimes, of local and global phase distinguishability. The scaling of
distinguishability in these regimes with photon number is explored for various
quantum states. It emerges that local distinguishability is dependent on a
discrepancy between quantum and classical rotational energy. Our analysis
demonstrates that the Heisenberg limit is the true upper limit for local phase
sensitivity. Only the `NOON' states share this bound, but other states exhibit
a better trade-off when comparing local and global phase regimes.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 03:38:20 GMT"
},
{
"version": "v2",
"created": "Wed, 20 Dec 2006 00:45:40 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Durkin",
"Gabriel A.",
""
],
[
"Dowling",
"Jonathan P.",
""
]
] |
quant-ph/0607089
|
Li Yang
|
Li Yang and Bao Li
|
Unconditionally Secure Quantum Bit Commitment Protocols Based on
Correlation Immune Boolean Function
| null | null | null | null |
quant-ph
| null |
A class of quantum protocols of bit commitment is constructed based on the
nonorthogonal states coding and the correlation immunity of some Boolean
functions. The binding condition of these protocols is guaranteed mainly by the
law of causality and the concealing condition is guaranteed by the
indistinguishability between nonorthogonal quantum states and the correlation
immunity of Boolean functions. We also give out an oblivious transfer protocol
based on two-nonorthogonal states coding and build a bit commitment protocol on
top of it. The relationship between these protocols and the well known no-go
theorem is also discussed in details.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 17:48:38 GMT"
},
{
"version": "v2",
"created": "Tue, 18 Jul 2006 14:44:15 GMT"
},
{
"version": "v3",
"created": "Wed, 19 Jul 2006 11:34:18 GMT"
},
{
"version": "v4",
"created": "Thu, 20 Jul 2006 15:39:09 GMT"
},
{
"version": "v5",
"created": "Fri, 21 Jul 2006 19:25:11 GMT"
},
{
"version": "v6",
"created": "Thu, 10 Aug 2006 23:05:56 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Yang",
"Li",
""
],
[
"Li",
"Bao",
""
]
] |
quant-ph/0607090
|
XiLi Zhang Dr.
|
X.L. Zhang, M. Feng, K.L. Gao
|
Efficient generation of entangled photons by cavity QED
|
7 pages, 3 figures, to appear in J. Phys. B
|
J. Phys. B: At. Mol. Opt. Phys. 39 (2006) 3211?C3219
|
10.1088/0953-4075/39/16/006
| null |
quant-ph
| null |
A potential scheme is proposed to generate complete sets of entangled photons
in the context of cavity quantum electrodynamics (QED). The scheme includes
twice interactions of atoms with cavities, in which the first interaction is
made in two-mode optical cavities and the second one exists in a microwave
cavity. In the optical cavities the atoms are resonant with the cavity modes,
while the detuned interaction of the atoms with a single-mode of the microwave
cavity is driven by a classical field. We show that our scheme is carried out
with higher efficiency than previeous schemes, and is close to the reach of
current technique.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 06:50:30 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Zhang",
"X. L.",
""
],
[
"Feng",
"M.",
""
],
[
"Gao",
"K. L.",
""
]
] |
quant-ph/0607091
|
Nobuyuki Takei
|
Nobuyuki Takei, Noriyuki Lee, Daiki Moriyama, J. S. Neergaard-Nielsen
and Akira Furusawa
|
Time domain Einstein-Podolsky-Rosen correlation
|
4 pages, 4 figures
|
Phys. Rev. A 74, 060101(R) (2006).
|
10.1103/PhysRevA.74.060101
| null |
quant-ph
| null |
We experimentally demonstrate creation and characterization of
Einstein-Podolsky-Rosen (EPR) correlation between optical beams in the time
domain. The correlated beams are created with two independent continuous-wave
optical parametric oscillators and a half beam splitter. We define temporal
modes using a square temporal filter with duration $T$ and make time-resolved
measurement on the generated state. We observe the correlations between the
relevant conjugate variables in time domain which correspond to the EPR
correlation. Our scheme is extendable to continuous variable quantum
teleportation of a non-Gaussian state defined in the time domain such as a
Schr\"odinger cat-like state.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 08:31:58 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Takei",
"Nobuyuki",
""
],
[
"Lee",
"Noriyuki",
""
],
[
"Moriyama",
"Daiki",
""
],
[
"Neergaard-Nielsen",
"J. S.",
""
],
[
"Furusawa",
"Akira",
""
]
] |
quant-ph/0607092
|
Jozef Ko\v{s}\'ik
|
Jozef Kosik, Vladimir Buzek, Mark Hillery
|
Quantum walks with random phase shifts
|
to appear in Phys. Rev. A (10 pages, 5 figures)
| null |
10.1103/PhysRevA.74.022310
| null |
quant-ph
| null |
We investigate quantum walks in multiple dimensions with different quantum
coins. We augment the model by assuming that at each step the amplitudes of the
coin state are multiplied by random phases. This model enables us to study in
detail the role of decoherence in quantum walks and to investigate the
quantum-to-classical transition. We also provide classical analogues of the
quantum random walks studied. Interestingly enough, it turns out that the
classical counterparts of some quantum random walks are classical random walks
with a memory and biased coin. In addition random phase shifts "simplify" the
dynamics (the cross interference terms of different paths vanish on average)
and enable us to give a compact formula for the dispersion of such walks.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 10:08:20 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Kosik",
"Jozef",
""
],
[
"Buzek",
"Vladimir",
""
],
[
"Hillery",
"Mark",
""
]
] |
quant-ph/0607093
|
Geraldo A. Barbosa
|
Geraldo A. Barbosa
|
Fundamentals for immediate implementation of a quantum secured Internet
|
8 pages and 6 figures. A typo in the eigenvalues in version V1 was
corrected and a few short comments added
| null | null | null |
quant-ph
| null |
This work shows how a secure Internet for users A and B can be implemented
through a fast key distribution system that uses physical noise to encrypt
information transmitted in deterministic form. Starting from a shared secret
random sequence between them, long sequences of fresh random bits can be shared
in a secure way and not involving a third party. The shared decrypted random
bits -encrypted by noise at the source- are subsequently utilized for
one-time-pad data encryption. The physical generated protection is not
susceptible to advances in computation or mathematics. In particular, it does
not depend on the difficulty of factoring numbers in primes. Also, there is no
use of Linear Feed Back Shift Registers. The attacker has free access to the
communication channels and may acquire arbitrary number of copies of the
transmitted signal without lowering the security level. No intrusion detection
method is needed.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 12:02:39 GMT"
},
{
"version": "v2",
"created": "Wed, 16 Aug 2006 23:04:55 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Barbosa",
"Geraldo A.",
""
]
] |
quant-ph/0607094
|
Michael M. Wolf
|
Christina V. Kraus, Michael M. Wolf, J. Ignacio Cirac
|
Quantum simulations under translational symmetry
|
9 pages, 2 figures, references added, minor changes
|
Phys. Rev. A 75, 022303 (2007)
|
10.1103/PhysRevA.75.022303
| null |
quant-ph
| null |
We investigate the power of quantum systems for the simulation of Hamiltonian
time evolutions on a cubic lattice under the constraint of translational
invariance. Given a set of translationally invariant local Hamiltonians and
short range interactions we determine time evolutions which can and those that
can not be simulated. Whereas for general spin systems no finite universal set
of generating interactions is shown to exist, universality turns out to be
generic for quadratic bosonic and fermionic nearest-neighbor interactions when
supplemented by all translationally invariant on-site Hamiltonians.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 12:16:57 GMT"
},
{
"version": "v2",
"created": "Wed, 6 Dec 2006 12:55:29 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Kraus",
"Christina V.",
""
],
[
"Wolf",
"Michael M.",
""
],
[
"Cirac",
"J. Ignacio",
""
]
] |
quant-ph/0607095
|
Alexandre Matzkin
|
A. Matzkin
|
Can Bohmian trajectories account for quantum recurrences having
classical periodicities?
| null |
Phys. Lett. A 361, 294 (2007).
|
10.1016/j.physleta.2006.09.052
| null |
quant-ph
| null |
Quantum systems in specific regimes display recurrences at the period of the
periodic orbits of the corresponding classical system. We investigate the
excited hydrogen atom in a magnetic field -- a prototypical system of 'quantum
chaos' -- from the point of view of the de Broglie Bohm (BB) interpretation of
quantum mechanics. The trajectories predicted by BB theory are computed and
contrasted with the time evolution of the wavefunction, which shows pronounced
features at times matching the period of closed orbits of the classical
hydrogen in a magnetic field problem. Individual BB trajectories do not possess
these periodicities and cannot account for the quantum recurrences. These
recurrences can however be explained by BB theory by considering the ensemble
of trajectories compatible with an initial statistical distribution, although
none of the trajectories of the ensemble are periodic, rendering unclear the
dynamical origin of the classical periodicities.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 12:27:38 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Matzkin",
"A.",
""
]
] |
quant-ph/0607096
|
Dr. Paul J. Werbos
|
Paul J. Werbos
|
Specification of the Q Hypothesis: An Alternative Mathematical
Foundation for Physics
|
New brief appendix explains in simpler terms what Q and P hypotheses
are, and why current empirical data appears to support the P hypothesis over
both the Q hypothesis and the current standard model of physics, with
reference to two new papers
| null | null | null |
quant-ph nucl-th
| null |
Mathematical tools related to coherence theory and classical-quantum
equivalence, due to Wigner and Glauber, are essential to modern, practical and
empirical understanding of electromagnetics in areas like quantum optics and
nanoelectronics. This paper specifies how an extension of these same tools
(especially Glauber's "Q" mapping) can be applied to strong nuclear forces as
well, and provides a "bottom-up" approach to axiomatic unification of physics,
grounded in empirical reality (dice included). The Q hypothesis also has
implications for quantum measurement and quantum information technology. The
basic hypothesis is that density matrices across all of quantum field theory
can be "decoded" or mapped usefully into probability distributions for
"classical" fields, by using a generalization of Glauber's Q mapping, which
does the same for electromagnetics.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 13:22:29 GMT"
},
{
"version": "v2",
"created": "Wed, 9 Aug 2006 16:04:10 GMT"
},
{
"version": "v3",
"created": "Fri, 25 Apr 2008 12:16:10 GMT"
}
] | 2008-04-25T00:00:00 |
[
[
"Werbos",
"Paul J.",
""
]
] |
quant-ph/0607097
|
Nikolai Chuprikov
|
N L Chuprikov and O V Spiridonova
|
A new type of solution of the Schr\"odinger equation on a self-similar
fractal potential
|
Latex, 4 pages, 7 eps-figures; the old figures are renewed and new
ones are added
|
J. Phys. A: Math. Gen. 39 (2006) L559-L562
|
10.1088/0305-4470/39/37/L01
| null |
quant-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Scattering a quantum particle by a self-similar fractal potential on a Cantor
set is investigated. We present a new type of solution of the functional
equation for the transfer matrix of this potential, which was derived earlier
from the Schr\"odinger equation.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 14:12:42 GMT"
},
{
"version": "v2",
"created": "Fri, 8 Sep 2006 03:25:00 GMT"
},
{
"version": "v3",
"created": "Fri, 4 Jul 2008 09:25:30 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Chuprikov",
"N L",
""
],
[
"Spiridonova",
"O V",
""
]
] |
quant-ph/0607098
|
Volker Hannstein
|
Volker Hannstein, Gerhard C. Hegerfeldt
|
How to measure the wave-function absolute squared of a moving particle
by using mirrors
|
4 pages, 5 figures
|
EPL, 77(2007) 60003
|
10.1209/0295-5075/77/60003
| null |
quant-ph
| null |
We consider a slow particle with wave function $\psi_t(\vec{x})$, moving
freely in some direction. A mirror is briefly switched on around a time $T$ and
its position is scanned. It is shown that the measured reflection probability
then allows the determination of $|\psi_T(\vec{x})|^2$. Experimentally
available atomic mirrors should make this method applicable to the
center-of-mass wave function of atoms with velocities in the cm/s range.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 14:43:47 GMT"
},
{
"version": "v2",
"created": "Tue, 19 Jun 2007 18:56:22 GMT"
}
] | 2007-06-19T00:00:00 |
[
[
"Hannstein",
"Volker",
""
],
[
"Hegerfeldt",
"Gerhard C.",
""
]
] |
quant-ph/0607099
|
Guang Wu
|
Guang Wu, Jie Chen, Yao Li, Lilin Xu and Heping Zeng
|
Prevent eavesdropping with bright reference pulses for practical quantum
key distribution
|
18 pages, 3 figures
|
Phys. Rev. A 74, 062323 (2006)
|
10.1103/PhysRevA.74.062323
| null |
quant-ph
| null |
We analyze the application of bright reference pulses to prevent the
photon-number-splitting attack in weak-pulse quantum key distribution. Under
the optimal eavesdropping strategy as far as we know, the optimal parameters of
bright reference and signal pulses can ensure a secure transmission distance up
to 146 km. To realize the quantum key distribution scenario with up-present
techniques, we present an experimentally feasible scheme to create a large
splitting ratio between bright reference and signal pulses, and to switch the
bright reference pulses away from signal pulses to avoid the after-pulse
disturbance.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 15:17:16 GMT"
},
{
"version": "v2",
"created": "Wed, 13 Sep 2006 04:37:26 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Wu",
"Guang",
""
],
[
"Chen",
"Jie",
""
],
[
"Li",
"Yao",
""
],
[
"Xu",
"Lilin",
""
],
[
"Zeng",
"Heping",
""
]
] |
quant-ph/0607100
|
Juan C. Agudelo
|
Juan C. Agudelo and Walter Carnielli
|
Quantum Computation via Paraconsistent Computation
| null | null | null | null |
quant-ph
| null |
We present an original model of paraconsistent Turing machines (PTMs), a
generalization of the classical Turing machines model of computation using a
paraconsistent logic. Next, we briefl y describe the standard models of quantum
computation: quantum Turing machines and quantum circuits, and revise quantum
algorithms to solve the so-called Deutsch's problem and Deutsch-Jozsa problem.
Then, we show the potentialities of the PTMs model of computation simulating
the presented quantum algorithms via paraconsistent algorithms. This way, we
show that PTMs can resolve some problems in exponentially less time than any
classical deterministic Turing machine. Finally, We show that it is not
possible to simulate all characteristics (in particular entangled states) of
quantum computation by the particular model of PTMs here presented, therefore
we open the possibility of constructing a new model of PTMs by which it is
feasible to simulate such states.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 18:47:58 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Agudelo",
"Juan C.",
""
],
[
"Carnielli",
"Walter",
""
]
] |
quant-ph/0607101
|
Onur Hosten
|
Onur Hosten, Matthew T. Rakher, Julio T. Barreiro, Nicholas A. Peters,
and Paul Kwiat
|
Counterfactual computation revisited
|
12 Pages, 8 Figures, 4 Tables in total. Mitchison and Jozsa responded
to our article and the current form includes a reply (5 pages) to them. The
text is unchanged otherwise. We provide two abstracts: one for the original
aricle, one for the updates
| null | null | null |
quant-ph
| null |
Mitchison and Jozsa recently suggested that the "chained-Zeno" counterfactual
computation protocol recently proposed by Hosten et al. is counterfactual for
only one output of the computer. This claim was based on the existing abstract
algebraic definition of counterfactual computation, and indeed according to
this definition, their argument is correct. However, a more general definition
(physically adequate) for counterfactual computation is implicitly assumed by
Hosten et. al. Here we explain in detail why the protocol is counterfactual and
how the "history tracking" method of the existing description inadequately
represents the physics underlying the protocol. Consequently, we propose a
modified definition of counterfactual computation. Finally, we comment on one
of the most interesting aspects of the error-correcting protocol.
|
[
{
"version": "v1",
"created": "Fri, 14 Jul 2006 20:36:30 GMT"
},
{
"version": "v2",
"created": "Sun, 6 Aug 2006 23:15:26 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Hosten",
"Onur",
""
],
[
"Rakher",
"Matthew T.",
""
],
[
"Barreiro",
"Julio T.",
""
],
[
"Peters",
"Nicholas A.",
""
],
[
"Kwiat",
"Paul",
""
]
] |
quant-ph/0607102
|
Kurt Jacobs
|
Kurt Jacobs, Pavel Lougovski and Miles Blencowe
|
Continous Measurement of the Energy Eigenstates of a Nanomechanical
Resonator without a Non-Demolition Probe
|
4 pages, revtex4, two eps figures. v2: new results, much improved
implementation; v4: published version, some terminology changed
|
Phys. Rev. Lett. 98, 147201 (2007)
|
10.1103/PhysRevLett.98.147201
| null |
quant-ph cond-mat.mes-hall
| null |
We show that it is possible to perform a continuous measurement that
continually projects a nano-resonator into its energy eigenstates by employing
a linear coupling with a two-state system. This technique makes it possible to
perform a measurement that exposes the quantum nature of the resonator by
coupling it to a Cooper-pair Box and a superconducting transmission-line
resonator.
|
[
{
"version": "v1",
"created": "Sat, 15 Jul 2006 03:35:39 GMT"
},
{
"version": "v2",
"created": "Sat, 30 Sep 2006 04:06:01 GMT"
},
{
"version": "v3",
"created": "Thu, 12 Oct 2006 02:40:48 GMT"
},
{
"version": "v4",
"created": "Tue, 3 Apr 2007 03:15:48 GMT"
}
] | 2013-05-29T00:00:00 |
[
[
"Jacobs",
"Kurt",
""
],
[
"Lougovski",
"Pavel",
""
],
[
"Blencowe",
"Miles",
""
]
] |
quant-ph/0607103
|
Murray Olsen Dr
|
M.K. Olsen, A.S. Bradley
|
Tripartite entanglement from interlinked $\chi^{(2)}$ parametric
interactions
|
15 pages, 5 figures
| null |
10.1103/PhysRevA.74.063809
| null |
quant-ph
| null |
We examine the tripartite entanglement properties of an optical system using
interlinked $\chi^{(2)}$ interactions, recently studied experimentally in terms
of its phase-matching properties by Bondani et al [M. Bondani, A. Allevi, E.
Gevinti, A. Agliati, and A. Andreoni, arXiv:quant-ph/0604002.]. We show that
the system does produce output modes which are genuinely tripartite entangled
and that detection of this entanglement depends crucially on the correlation
functions which are measured, with a three-mode Einstein-Podolsky-Rosen
inequality being the most sensitive.
|
[
{
"version": "v1",
"created": "Sat, 15 Jul 2006 06:21:49 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Olsen",
"M. K.",
""
],
[
"Bradley",
"A. S.",
""
]
] |
quant-ph/0607104
|
Miloslav Znojil
|
Miloslav Znojil and Hendrik B. Geyer
|
Construction of a unique metric in quasi-Hermitian quantum mechanics:
non-existence of the charge operator in a 2 x 2 matrix model
|
13 pages
|
Physics Letters B 640 (2006) 52 - 56
|
10.1016/j.physletb.2006.07.028
| null |
quant-ph
| null |
For a specific exactly solvable 2 by 2 matrix model with a PT-symmetric
Hamiltonian possessing a real spectrum, we construct all the eligible physical
metrics and show that none of them admits a factorization CP in terms of an
involutive charge operator C. Alternative ways of restricting the physical
metric to a unique form are briefly discussed.
|
[
{
"version": "v1",
"created": "Sat, 15 Jul 2006 08:46:01 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Znojil",
"Miloslav",
""
],
[
"Geyer",
"Hendrik B.",
""
]
] |
quant-ph/0607105
|
Enrique Solano
|
Y. Delgado, L. Lamata, J. Leon, D. Salgado, and E. Solano
|
Sequential Quantum Cloning
|
4 pages, no figures. New version with changes. Accepted in Physical
Review Letters
|
Phys. Rev. Lett. 98, 150502 (2007).
|
10.1103/PhysRevLett.98.150502
| null |
quant-ph
| null |
Not all unitary operations upon a set of qubits can be implemented by
sequential interactions between each qubit and an ancillary system. We analyze
the specific case of sequential quantum cloning 1->M and prove that the minimal
dimension D of the ancilla grows linearly with the number of clones M. In
particular, we obtain D = 2M for symmetric universal quantum cloning and D =
M+1 for symmetric phase-covariant cloning. Furthermore, we provide a recipe for
the required ancilla-qubit interactions in each step of the sequential
procedure for both cases.
|
[
{
"version": "v1",
"created": "Sat, 15 Jul 2006 09:16:14 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Mar 2007 22:20:32 GMT"
}
] | 2015-06-26T00:00:00 |
[
[
"Delgado",
"Y.",
""
],
[
"Lamata",
"L.",
""
],
[
"Leon",
"J.",
""
],
[
"Salgado",
"D.",
""
],
[
"Solano",
"E.",
""
]
] |
quant-ph/0607106
|
Eyal Buks
|
Eyal Buks and M. P. Blencowe
|
Decoherence and Recoherence in a Vibrating RF SQUID
|
9 pages, 2 figures
| null |
10.1103/PhysRevB.74.174504
| null |
quant-ph cond-mat.mes-hall cond-mat.supr-con
| null |
We study an RF SQUID, in which a section of the loop is a freely suspended
beam that is allowed to oscillate mechanically. The coupling between the RF
SQUID and the mechanical resonator originates from the dependence of the total
magnetic flux threading the loop on the displacement of the resonator. Motion
of the latter affects the visibility of Rabi oscillations between the two
lowest energy states of the RF SQUID. We address the feasibility of
experimental observation of decoherence and recoherence, namely decay and rise
of the visibility, in such a system.
|
[
{
"version": "v1",
"created": "Sun, 16 Jul 2006 12:45:47 GMT"
},
{
"version": "v2",
"created": "Thu, 20 Jul 2006 16:36:44 GMT"
},
{
"version": "v3",
"created": "Tue, 19 Sep 2006 06:44:21 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Buks",
"Eyal",
""
],
[
"Blencowe",
"M. P.",
""
]
] |
quant-ph/0607107
|
Peter Turner
|
Stephen D. Bartlett, Terry Rudolph, Barry C. Sanders and Peter S.
Turner
|
Degradation of a quantum directional reference frame as a random walk
|
5 pages, no figures. Comments are welcome. v2: several changes to
clarify the key results. v3: journal reference added, acknowledgements and
references updated
|
J. Mod. Opt., 54, 2211 (2007)
|
10.1080/09500340701289254
| null |
quant-ph
| null |
We investigate if the degradation of a quantum directional reference frame
through repeated use can be modeled as a classical direction undergoing a
random walk on a sphere. We demonstrate that the behaviour of the fidelity for
a degrading quantum directional reference frame, defined as the average
probability of correctly determining the orientation of a test system, can be
fit precisely using such a model. Physically, the mechanism for the random walk
is the uncontrollable back-action on the reference frame due to its use in a
measurement of the direction of another system. However, we find that the
magnitude of the step size of this random walk is not given by our classical
model and must be determined from the full quantum description.
|
[
{
"version": "v1",
"created": "Mon, 17 Jul 2006 02:18:16 GMT"
},
{
"version": "v2",
"created": "Thu, 12 Oct 2006 23:28:46 GMT"
},
{
"version": "v3",
"created": "Wed, 10 Oct 2007 00:09:18 GMT"
}
] | 2007-10-10T00:00:00 |
[
[
"Bartlett",
"Stephen D.",
""
],
[
"Rudolph",
"Terry",
""
],
[
"Sanders",
"Barry C.",
""
],
[
"Turner",
"Peter S.",
""
]
] |
quant-ph/0607108
|
Ye Yeo
|
Ye Yeo
|
Teleportation with a Mixed State of Four Qubits and the Generalized
Singlet Fraction
|
11 pages
| null |
10.1103/PhysRevA.74.052305
| null |
quant-ph
| null |
Recently, an explicit protocol ${\cal E}_0$ for faithfully teleporting
arbitrary two-qubit states using genuine four-qubit entangled states was
presented by us [Phys. Rev. Lett. {\bf 96}, 060502 (2006)]. Here, we show that
${\cal E}_0$ with an arbitrary four-qubit mixed state resource $\Xi$ is
equivalent to a generalized depolarizing bichannel with probabilities given by
the maximally entangled components of the resource. These are defined in terms
of our four-qubit entangled states. We define the generalized singlet fraction
${\cal G}[\Xi]$, and illustrate its physical significance with several
examples. We argue that in order to teleport arbitrary two-qubit states with
average fidelity better than is classically possible, we have to demand that
${\cal G}[\Xi] > 1/2$. In addition, we conjecture that when ${\cal G}[\Xi] <
1/4$ then no entanglement can be teleported. It is shown that to determine the
usefulness of $\Xi$ for ${\cal E}_0$, it is necessary to analyze ${\cal
G}[\Xi]$.
|
[
{
"version": "v1",
"created": "Mon, 17 Jul 2006 09:02:49 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Yeo",
"Ye",
""
]
] |
quant-ph/0607109
|
Stephen Adler
|
Stephen L. Adler
|
Normalization of Collisional Decoherence: Squaring the Delta Function,
and an Independent Cross-Check
|
Tex: 14 pages 7/30/06: revisions to introduction, and references
added 9/29/06: further minor revisions and references added
|
J.Phys. A39 (2006) 14067-14074
|
10.1088/0305-4470/39/45/015
| null |
quant-ph hep-ph hep-th math-ph math.MP
| null |
We show that when the Hornberger--Sipe calculation of collisional decoherence
is carried out with the squared delta function a delta of energy instead of a
delta of the absolute value of momentum, following a method introduced by
Di\'osi, the corrected formula for the decoherence rate is simply obtained. The
results of Hornberger and Sipe and of Di\'osi are shown to be in agreement. As
an independent cross-check, we calculate the mean squared coordinate diffusion
of a hard sphere implied by the corrected decoherence master equation, and show
that it agrees precisely with the same quantity as calculated by a classical
Brownian motion analysis.
|
[
{
"version": "v1",
"created": "Mon, 17 Jul 2006 14:36:09 GMT"
},
{
"version": "v2",
"created": "Mon, 31 Jul 2006 14:56:46 GMT"
},
{
"version": "v3",
"created": "Fri, 29 Sep 2006 17:31:43 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Adler",
"Stephen L.",
""
]
] |
quant-ph/0607110
|
Lajos Di\'osi
|
Lajos Di\'osi
|
Notes on Certain Newton Gravity Mechanisms of Wave Function Localisation
and Decoherence
|
8pp LaTex, Submitted to J. Phys. A: Math-Gen, for the special issue
``The Quantum Universe'' in honor of G. C. Ghirardi
|
J.Phys. A40 (2007) 2989-2995
|
10.1088/1751-8113/40/12/S07
| null |
quant-ph
| null |
Both the additional non-linear term in the Schr\"odinger equation and the
additional non-Hamiltonian term in the von Neumann equation, proposed to ensure
localisation and decoherence of macro-objects, resp., contain the same
Newtonian interaction potential formally. We discuss certain aspects that are
common for both equations. In particular, we calculate the enhancement of the
proposed localisation and/or decoherence effects, which would take place if one
could lower the conventional length-cutoff and resolve the mass density on the
interatomic scale.
|
[
{
"version": "v1",
"created": "Mon, 17 Jul 2006 15:47:42 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Diósi",
"Lajos",
""
]
] |
quant-ph/0607111
|
P. G. L. Porta Mana
|
P. G. L. Porta Mana, A. M{\aa}nsson, G. Bj\"ork
|
`Plausibilities of plausibilities': an approach through circumstances
|
30 pages, 3 figures. V2: clarified some points and corrected some
typos. V3: corrected typos and added references
| null | null | null |
quant-ph cs.AI
| null |
Probability-like parameters appearing in some statistical models, and their
prior distributions, are reinterpreted through the notion of `circumstance', a
term which stands for any piece of knowledge that is useful in assigning a
probability and that satisfies some additional logical properties. The idea,
which can be traced to Laplace and Jaynes, is that the usual inferential
reasonings about the probability-like parameters of a statistical model can be
conceived as reasonings about equivalence classes of `circumstances' - viz.,
real or hypothetical pieces of knowledge, like e.g. physical hypotheses, that
are useful in assigning a probability and satisfy some additional logical
properties - that are uniquely indexed by the probability distributions they
lead to.
|
[
{
"version": "v1",
"created": "Mon, 17 Jul 2006 17:14:19 GMT"
},
{
"version": "v2",
"created": "Mon, 31 Jul 2006 17:48:45 GMT"
},
{
"version": "v3",
"created": "Sun, 29 Apr 2007 12:09:41 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Mana",
"P. G. L. Porta",
""
],
[
"Månsson",
"A.",
""
],
[
"Björk",
"G.",
""
]
] |
quant-ph/0607112
|
Berry Groisman
|
Berry Groisman
|
Reliable entanglement transfer between pure quantum states
|
6 pages, 4 pictures; revised version; to appear in Phys. Rev. A
|
Phys. Rev. A 74, 042302 (2006)
|
10.1103/PhysRevA.74.042302
| null |
quant-ph
| null |
The problem of the reliable transfer of entanglement from one pure bipartite
quantum state to another using local operations is analyzed. It is shown that
in the case of qubits the amount that can be transferred is restricted to the
difference between the entanglement of the two states. In the presence of a
catalytic state the range of the transferrable amount broadens to a certain
degree.
|
[
{
"version": "v1",
"created": "Mon, 17 Jul 2006 17:09:20 GMT"
},
{
"version": "v2",
"created": "Tue, 3 Oct 2006 11:38:35 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Groisman",
"Berry",
""
]
] |
quant-ph/0607113
|
Fernando Gomez
|
F. Gomez
|
The Role of Resonances in the Stochastic Limit
|
20 pages
| null | null | null |
quant-ph
| null |
In the stochastic limit the resonances play a fundamental role because they
determine the generalized susceptivities which are the building blocks of all
the physical information which survives in this limit. There are two sources of
possible divergences: one related to the singularities of the form factor;
another to the chaoticity of the spectrum. The situation will be illustrated
starting from the example of the discrete part of the hydrogen atom in
interaction with the electromagnetic field.
|
[
{
"version": "v1",
"created": "Mon, 17 Jul 2006 17:55:05 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Gomez",
"F.",
""
]
] |
quant-ph/0607114
|
Mankei Tsang
|
Mankei Tsang (California Institute of Technology)
|
On the Relationship between Resolution Enhancement and Multiphoton
Absorption Rate in Quantum Lithography
|
14 pages, 7 figures, submitted, v2: rewritten in response to
referees' comments, v3: rewritten and extended, v4: accepted by Physical
Review A
|
Physical Review A 75, 043813 (2007)
|
10.1103/PhysRevA.75.043813
| null |
quant-ph
| null |
The proposal of quantum lithography [Boto et al., Phys. Rev. Lett. 85, 2733
(2000)] is studied via a rigorous formalism. It is shown that, contrary to Boto
et al.'s heuristic claim, the multiphoton absorption rate of a ``NOON'' quantum
state is actually lower than that of a classical state with otherwise identical
parameters. The proof-of-concept experiment of quantum lithography [D'Angelo et
al., Phys. Rev. Lett. 87, 013602 (2001)] is also analyzed in terms of the
proposed formalism, and the experiment is shown to have a reduced multiphoton
absorption rate in order to emulate quantum lithography accurately. Finally,
quantum lithography by the use of a jointly Gaussian quantum state of light is
investigated, in order to illustrate the trade-off between resolution
enhancement and multiphoton absorption rate.
|
[
{
"version": "v1",
"created": "Mon, 17 Jul 2006 19:27:56 GMT"
},
{
"version": "v2",
"created": "Wed, 20 Sep 2006 23:01:15 GMT"
},
{
"version": "v3",
"created": "Fri, 27 Oct 2006 05:44:03 GMT"
},
{
"version": "v4",
"created": "Wed, 28 Feb 2007 20:12:01 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Tsang",
"Mankei",
"",
"California Institute of Technology"
]
] |
quant-ph/0607115
|
Andrew Scott Parkins
|
F. Dimer, B. Estienne, A.S. Parkins, H.J. Carmichael
|
Proposed realization of the Dicke-model quantum phase transition in an
optical cavity QED system
|
15 pages, 12 figures
| null |
10.1103/PhysRevA.75.013804
| null |
quant-ph
| null |
The Dicke model consisting of an ensemble of two-state atoms interacting with
a single quantized mode of the electromagnetic field exhibits a
zero-temperature phase transition at a critical value of the dipole coupling
strength. We propose a scheme based on multilevel atoms and cavity-mediated
Raman transitions to realise an effective Dicke system operating in the phase
transition regime. Output light from the cavity carries signatures of the
critical behavior which is analyzed for the thermodynamic limit where the
number of atoms is very large.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 05:26:14 GMT"
}
] | 2015-06-26T00:00:00 |
[
[
"Dimer",
"F.",
""
],
[
"Estienne",
"B.",
""
],
[
"Parkins",
"A. S.",
""
],
[
"Carmichael",
"H. J.",
""
]
] |
quant-ph/0607116
|
Cunbing Huang
|
Xin-Wei Zha and Cun-Bing Huang
|
The expansion of orthogonal complete set and teleportation of an
arbitrary two-qubit state
|
12 pages, 1 table
| null | null | null |
quant-ph
| null |
In accordance with the principle of superposition and operator rule, the
state of the whole system composed of the state of the particles to be
teleported and quantum channel can be expanded by Bell bases and transformation
operator. Theoretically, if determinant of transformation operators is not
zero, the teleportation can be realized only by performing an inverse
transformation. Actually, if the transformation operator is not a unitary
operation, then by using one auxiliary qubits, the teleportation can be
realized only by performing a collective unitary transformation. Moreover, the
further analysis of the relationship between collective unitary operation and
transformation operators is discussed.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 06:32:21 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Zha",
"Xin-Wei",
""
],
[
"Huang",
"Cun-Bing",
""
]
] |
quant-ph/0607117
|
Ting Wang
|
Ting Wang, Xiaoguang Wang, and Zhe Sun
|
Entanglement oscillations in open Heisenberg chains
|
5 pages, 4 figures
| null |
10.1016/j.physa.2007.04.100
| null |
quant-ph
| null |
We study pairwise entanglements in spin-half and spin-one Heisenberg chains
with an open boundary condition, respectively. We find out that the
ground-state and the first-excited-state entanglements are equal for the
three-site spin-one chain. When the number of sites L>3, the concurrences and
negativities display oscillatory behaviors, and the oscillations of the
ground-state and the first-excited-state entanglements are out of phase or in
phase.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 07:41:53 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Wang",
"Ting",
""
],
[
"Wang",
"Xiaoguang",
""
],
[
"Sun",
"Zhe",
""
]
] |
quant-ph/0607118
|
Daniel Comparat
|
Daniel Comparat (LAC)
|
General conditions for a quantum adiabatic evolution
|
4 pages
| null | null | null |
quant-ph
| null |
The smallness of the variation rate of the hamiltonian matrix elements
compared to the (square of the) energy spectrum gap is usually believed to be
the key parameter for a quantum adiabatic evolution. However it is only
perturbatively valid for scaled timed hamiltonian and resonance processes as
well as off resonance possible constructive St\"{u}ckelberg interference
effects violate this usual condition for general hamiltionian. More general
adiabatic condition and exact bounds for adiabatic quantum evolution are
derived and studied in the framework of a two-level system. The usual criterion
is restored for real two level hamiltonian with small number of monotonicity
changes of the hamiltonian matrix elements and its derivative.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 07:10:42 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Comparat",
"Daniel",
"",
"LAC"
]
] |
quant-ph/0607119
|
Stefano Pironio
|
Miguel Navascues, Stefano Pironio, Antonio Acin
|
Bounding the set of quantum correlations
|
5 pages, no figures. v2: minor modifications
|
Phys. Rev. Lett. 98, 010401 (2007)
|
10.1103/PhysRevLett.98.010401
| null |
quant-ph
| null |
We introduce a hierarchy of conditions necessarily satisfied by any
distribution P(ab) representing the probabilities for two separate observers to
obtain outcomes a and b when making local measurements on a shared quantum
state. Each condition in this hierarchy is formulated as a semidefinite
program. Our approach can be used to obtain upper-bounds on the quantum
violation of an arbitrary Bell inequality. It yields, for instance, tight
bounds for the violations of the Collins et al. inequalities.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 08:18:11 GMT"
},
{
"version": "v2",
"created": "Sat, 29 Mar 2008 21:36:15 GMT"
}
] | 2008-03-30T00:00:00 |
[
[
"Navascues",
"Miguel",
""
],
[
"Pironio",
"Stefano",
""
],
[
"Acin",
"Antonio",
""
]
] |
quant-ph/0607120
|
Ali Mostafazadeh
|
Ali Mostafazadeh and Seher Ozcelik
|
Explicit Realization of Pseudo-Hermitian and Quasi-Hermitian Quantum
Mechanics for Two-Level Systems
|
published version, 11 pages, contributed to the Proceedings of the
5th Worksop on Quantization, Dualities, and Integrable Systems, held in
Pamukkale University, Denizle, Turkey, 23-27 January, 2006
|
Turk J. Phys. 30, 437-443 (2006)
| null | null |
quant-ph
| null |
We give an explicit characterization of the most general quasi-Hermitian
operator H, the associated metric operators \eta_+, and \eta_+-pseudo-Hermitian
operators acting in two-dimensional complex Euclidean space C^2. These
operators represent the physical observables of a model whose Hamiltonian and
Hilbert space are respectively H and C^2 endowed with the inner product defined
by \eta_+. Our calculations allows for a direct demonstration of the fact that
the choice of an irreducible family of observables fixes the metric operator up
to a multiplicative factor.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 07:25:26 GMT"
},
{
"version": "v2",
"created": "Tue, 28 Nov 2006 08:51:41 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Mostafazadeh",
"Ali",
""
],
[
"Ozcelik",
"Seher",
""
]
] |
quant-ph/0607121
|
Dirk Seidel
|
D. Seidel, J.G. Muga, G.C. Hegerfeldt
|
Scattering of two-level atoms by delta lasers: Exactly solvable models
in atom optics
|
11 pages, 5 figures
| null |
10.1088/0953-4075/39/22/011
| null |
quant-ph
| null |
We study the scattering of two-level atoms at narrow laser fields, modeled by
a $\delta$-shape intensity profile. The unique properties of these potentials
allow us to give simple analytic solutions for one or two field zones. Several
applications are studied: a single $\delta$-laser may serve as a detector model
for atom detection and arrival-time measurements, either by means of
fluorescence or variations in occupation probabilities. We show that, in
principle, this ideal detector can measure the particle density, the quantum
mechanical flux, arrival time distributions or local kinetic energy densities.
Moreover, two spatially separated $\delta$-lasers are used to investigate
quantized-motion effects on Ramsey interferometry.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 10:21:58 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Seidel",
"D.",
""
],
[
"Muga",
"J. G.",
""
],
[
"Hegerfeldt",
"G. C.",
""
]
] |
quant-ph/0607122
|
Quesne Christiane
|
B. Bagchi, P.S. Gorain, C. Quesne
|
Morse potential and its relationship with the Coulomb in a
position-dependent mass background
|
9 pages, no figure; final published version
|
Mod. Phys. Lett. A 21 (2006) 2703-2708
|
10.1142/S0217732306021888
|
ULB/229/CQ/06/4
|
quant-ph math-ph math.MP
| null |
We provide some explicit examples wherein the Schr\"odinger equation for the
Morse potential remains exactly solvable in a position-dependent mass
background. Furthermore, we show how in such a context, the map from the full
line $(- \infty, \infty)$ to the half line $(0, \infty)$ may convert an exactly
solvable Morse potential into an exactly solvable Coulomb one. This generalizes
a well-known property of constant-mass problems.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 12:34:59 GMT"
},
{
"version": "v2",
"created": "Mon, 4 Dec 2006 13:36:20 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Bagchi",
"B.",
""
],
[
"Gorain",
"P. S.",
""
],
[
"Quesne",
"C.",
""
]
] |
quant-ph/0607123
|
Martin Plesch
|
Michal Sedlak and Martin Plesch
|
Towards optimization of quantum circuits
|
10 pages, 11 figures, minor changes+typos
|
Cent. Eur. J. Phys. vol. 6 no.1 p. 128-134 (2008)
|
10.2478/s11534-008-0039-8
| null |
quant-ph
| null |
Any unitary operation in quantum information processing can be implemented
via a sequence of simpler steps - quantum gates. However, actual implementation
of a quantum gate is always imperfect and takes a finite time. Therefore,
seeking for a short sequence of gates - efficient quantum circuit for a given
operation, is an important task. We contribute to this issue by proposing
optimization of the well-known universal procedure proposed by Barenco et.al
[1]. We also created a computer program which realizes both Barenco's
decomposition and the proposed optimization. Furthermore, our optimization can
be applied to any quantum circuit containing generalized Toffoli gates,
including basic quantum gate circuits.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 13:04:17 GMT"
},
{
"version": "v2",
"created": "Wed, 8 Nov 2006 15:31:16 GMT"
}
] | 2009-09-29T00:00:00 |
[
[
"Sedlak",
"Michal",
""
],
[
"Plesch",
"Martin",
""
]
] |
quant-ph/0607124
|
Roderich Tumulka
|
Roderich Tumulka
|
The "Unromantic Pictures" of Quantum Theory
|
37 pages LaTeX, no figures; written for special volume of J. Phys. A
in honor of G.C. Ghirardi
|
J.Phys.A40:3245-3273,2007
|
10.1088/1751-8113/40/12/S22
| null |
quant-ph
| null |
I am concerned with two views of quantum mechanics that John S. Bell called
``unromantic'': spontaneous wave function collapse and Bohmian mechanics. I
discuss some of their merits and report about recent progress concerning
extensions to quantum field theory and relativity. In the last section, I
speculate about an extension of Bohmian mechanics to quantum gravity.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 15:48:46 GMT"
}
] | 2008-11-26T00:00:00 |
[
[
"Tumulka",
"Roderich",
""
]
] |
quant-ph/0607125
|
Jeffrey H. Shapiro
|
Baris I. Erkmen, Jeffrey H. Shapiro
|
Phase-conjugate optical coherence tomography
|
4 pages, 3 figures
| null |
10.1103/PhysRevA.74.041601
| null |
quant-ph
| null |
Quantum optical coherence tomography (Q-OCT) offers a factor-of-two
improvement in axial resolution and the advantage of even-order dispersion
cancellation when it is compared to conventional OCT (C-OCT). These features
have been ascribed to the non-classical nature of the biphoton state employed
in the former, as opposed to the classical state used in the latter.
Phase-conjugate OCT (PC-OCT), introduced here, shows that non-classical light
is not necessary to reap Q-OCT's advantages. PC-OCT uses classical-state signal
and reference beams, which have a phase-sensitive cross-correlation, together
with phase conjugation to achieve the axial resolution and even-order
dispersion cancellation of Q-OCT with a signal-to-noise ratio that can be
comparable to that of C-OCT.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 16:15:42 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Erkmen",
"Baris I.",
""
],
[
"Shapiro",
"Jeffrey H.",
""
]
] |
quant-ph/0607126
|
Ben Fortescue
|
Ben Fortescue, Hoi-Kwong Lo (Center for Quantum Information and
Quantum Control, University of Toronto)
|
Random bipartite entanglement from W and W-like states
|
5 pages, 1 figure, RevTeX. v2 - upper bound on random distillation is
expressed more generally and corollaries to the bound added. Minor notation
changes. v3 - further notation changes (Ernd now designated Et), discussion
of finite distillation rounds and single-copy bound on Et added. Theorem
added - relative entropy is shown to be an upper bound to Et for all pure
states. Discussion of W formation from EPRs (previously shown in others'
work) removed. Some addition, removal and reordering of references
|
Phys. Rev. Lett. 98, 260501 (2007)
|
10.1103/PhysRevLett.98.260501
| null |
quant-ph
| null |
We describe a protocol for distilling maximally entangled bipartite states
between random pairs of parties from those sharing a tripartite W state, and
show that, rather surprisingly, the total distillation rate (the total number
of EPR pairs distilled per W, irrespective of who shares them) may be done at a
higher rate than distillation of bipartite entanglement between specified pairs
of parties. Specifically, the optimal distillation rate for specified
entanglement for the W has been previously shown to be the asymptotic
entanglement of assistance of 0.92 EPR pairs per W, while our protocol can
asymptotically distill 1 EPR pair per W between random pairs of parties, which
we conjecture to be optimal. We thus demonstrate a tradeoff between the overall
asymptotic rate of EPR distillation and the distribution of final EPR pairs
between parties. We further show that by increasing the number of parties in
the protocol that there exist states with fixed lower-bounded distillable
entanglement for random parties but arbitrarily small distillable entanglement
for specified parties.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 18:38:03 GMT"
},
{
"version": "v2",
"created": "Wed, 20 Sep 2006 23:06:17 GMT"
},
{
"version": "v3",
"created": "Fri, 23 Feb 2007 15:45:07 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Fortescue",
"Ben",
"",
"Center for Quantum Information and\n Quantum Control, University of Toronto"
],
[
"Lo",
"Hoi-Kwong",
"",
"Center for Quantum Information and\n Quantum Control, University of Toronto"
]
] |
quant-ph/0607127
|
Fred Thaheld H
|
Fred H. Thaheld
|
A modified approach to the measurement problem: Objective reduction in
the retinal molecule prior to conformational change
|
8 pages. A new theory is advanced where the collapse of the wave
function now takes place within the retinal molecule, specifically the
retinal chromophore. This occurs prior to any retinal molecule conformational
change and before any CSL-type reduction mechanism in the retinal rod cells
|
BioSystems 92 (2008) 114-116
| null | null |
quant-ph physics.bio-ph
| null |
A new analysis of the measurement problem reveals the possibility that
collapse of the wavefunction may now take place just before photoisomerization
of the rhodopsin molecule in the retinal rods. It is known that when a photon
is initially absorbed by the retinal molecule which, along with opsin comprises
the rhodopsin molecule, an electron in the highest pi orbital is immediately
excited to a pi* orbital. This means that a measurement or transfer of
information takes place at the quantum level before the retinal molecule
commences the conformational change from cis to trans. This could have profound
implications for resolving some of the foundational issues confronting quantum
mechanics.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 23:21:24 GMT"
},
{
"version": "v2",
"created": "Fri, 4 Jan 2008 16:01:10 GMT"
},
{
"version": "v3",
"created": "Thu, 17 Apr 2008 06:00:00 GMT"
}
] | 2008-04-17T00:00:00 |
[
[
"Thaheld",
"Fred H.",
""
]
] |
quant-ph/0607128
|
Xuexi Yi
|
S. Li, H. Wang, Y. D. Sun, and X. X. Yi
|
Quantum heat engine with continuum working medium
|
5 pages, 3 figures
|
J. Phys. A 40, 8655-8664 (2007)
|
10.1088/1751-8113/40/30/004
| null |
quant-ph
| null |
We introduce a new quantum heat engine, in which the working medium is a
quantum system with a discrete level and a continuum. Net work done by this
engine is calculated and discussed. The results show that this quantum heat
engine behaves like the two-level quantum heat engine in both the
high-temperature and the low-temperature limits, but it operates differently in
temperatures between them. The efficiency of this quantum heat engine is also
presented and discussed.
|
[
{
"version": "v1",
"created": "Tue, 18 Jul 2006 23:35:36 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Li",
"S.",
""
],
[
"Wang",
"H.",
""
],
[
"Sun",
"Y. D.",
""
],
[
"Yi",
"X. X.",
""
]
] |
quant-ph/0607129
|
ChengZhi Peng
|
Cheng-Zhi Peng, Jun Zhang, Dong Yang, Wei-Bo Gao, Huai-Xin Ma, Hao
Yin, He-Ping Zeng, Tao Yang, Xiang-Bin Wang, Jian-Wei Pan
|
Experimental Long-Distance Decoy-State Quantum Key Distribution Based On
Polarization Encoding
|
4 pages,3 figures
|
Phys. Rev. Lett. 98, 010505 (2007)
|
10.1103/PhysRevLett.98.010505
| null |
quant-ph
| null |
We demonstrate the decoy-state quantum key distribution (QKD) with one-way
quantum communication in polarization space over 102km. Further, we simplify
the experimental setup and use only one detector to implement the one-way
decoy-state QKD over 75km, with the advantage to overcome the security
loopholes due to the efficiency mismatch of detectors. Our experimental
implementation can really offer the unconditionally secure final keys. We use 3
different intensities of 0, 0.2 and 0.6 for the pulses of source in our
experiment. In order to eliminate the influences of polarization mode
dispersion in the long-distance single-mode optical fiber, an automatic
polarization compensation system is utilized to implement the active
compensation.
|
[
{
"version": "v1",
"created": "Wed, 19 Jul 2006 00:38:42 GMT"
},
{
"version": "v2",
"created": "Thu, 17 Aug 2006 15:26:25 GMT"
},
{
"version": "v3",
"created": "Tue, 9 Jan 2007 07:12:59 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Peng",
"Cheng-Zhi",
""
],
[
"Zhang",
"Jun",
""
],
[
"Yang",
"Dong",
""
],
[
"Gao",
"Wei-Bo",
""
],
[
"Ma",
"Huai-Xin",
""
],
[
"Yin",
"Hao",
""
],
[
"Zeng",
"He-Ping",
""
],
[
"Yang",
"Tao",
""
],
[
"Wang",
"Xiang-Bin",
""
],
[
"Pan",
"Jian-Wei",
""
]
] |
quant-ph/0607130
|
Zheng-Xin Liu
|
Zheng-Xin Liu, Xiao-Ting Zhou, Xin Liu, Xiong-Jun Liu, Jing-Ling Chen
|
Topological structures of adiabatic phase for multi-level quantum
systems
|
15 pages, no figures. Accepted by J.Phys.A
|
J.Phys. A40 (2007) 1661-1676
|
10.1088/1751-8113/40/7/015
| null |
quant-ph
| null |
The topological properties of adiabatic gauge fields for multi-level
(three-level in particular) quantum systems are studied in detail. Similar to
the result that the adiabatic gauge field for SU(2) systems (e.g. two-level
quantum system or angular momentum systems, etc) have a monopole structure, the
curvature two-forms of the adiabatic holonomies for SU(3) three-level and SU(3)
eight-level quantum systems are shown to have monopole-like (for all levels) or
instanton-like (for the degenerate levels) structures.
|
[
{
"version": "v1",
"created": "Wed, 19 Jul 2006 08:31:36 GMT"
},
{
"version": "v2",
"created": "Fri, 4 Aug 2006 12:39:12 GMT"
},
{
"version": "v3",
"created": "Fri, 15 Sep 2006 07:48:32 GMT"
},
{
"version": "v4",
"created": "Thu, 11 Jan 2007 14:38:33 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Liu",
"Zheng-Xin",
""
],
[
"Zhou",
"Xiao-Ting",
""
],
[
"Liu",
"Xin",
""
],
[
"Liu",
"Xiong-Jun",
""
],
[
"Chen",
"Jing-Ling",
""
]
] |
quant-ph/0607131
|
Farhan Saif
|
Farhan Saif and Pierre Meystre
|
Coherent acceleration of material wavepackets in modulated optical
fields
| null | null |
10.1103/PhysRevA.75.043610
| null |
quant-ph
| null |
We study the quantum dynamics of a material wavepacket bouncing off a
modulated atomic mirror in the presence of a gravitational field. We find the
occurrence of coherent accelerated dynamics for atoms beyond the familiar
regime of dynamical localization. The acceleration takes place for certain
initial phase space data and within specific windows of modulation strengths.
The realization of the proposed acceleration scheme is within the range of
present day experimental possibilities.
|
[
{
"version": "v1",
"created": "Wed, 19 Jul 2006 19:03:59 GMT"
}
] | 2015-06-26T00:00:00 |
[
[
"Saif",
"Farhan",
""
],
[
"Meystre",
"Pierre",
""
]
] |
quant-ph/0607132
|
Jonathan Halliwell
|
J.J.Halliwell
|
Two Derivations of the Master Equation of Quantum Brownian Motion
|
19 pages, RevTex
| null |
10.1088/1751-8113/40/12/S11
| null |
quant-ph
| null |
Central to many discussion of decoherence is a master equation for the
reduced density matrix of a massive particle experiencing scattering from its
surrounding environment, such as that of Joos and Zeh. Such master equations
enjoy a close relationship with spontaneous localization models, like the GRW
model. This aim of this paper is to present two derivations of the master
equation. The first derivation is a pedagogical model designed to illustrate
the origins of the master equation as simply as possible, focusing on physical
principles and without the complications of S-matrix theory. This derivation
may serve as a useful tutorial example for students attempting to learn this
subject area. The second is the opposite: a very general derivation using
non-relativistic many body field theory. It reduces to the equation of the type
given by Joos and Zeh in the one-particle sector, but correcting certain
numerical factors which have recently become significant in connection with
experimental tests of decoherence. This master equation also emphasizes the
role of local number density as the ``preferred basis'' for decoherence in this
model.
|
[
{
"version": "v1",
"created": "Wed, 19 Jul 2006 13:45:12 GMT"
}
] | 2015-06-26T00:00:00 |
[
[
"Halliwell",
"J. J.",
""
]
] |
quant-ph/0607133
|
Giovanni Salesi
|
P. Falsaperla, G. Fonte and G. Salesi
|
Quantum Lyapunov Exponents
|
15 pages, 10 figures
|
Found. Phys. 32 (2002) 267
| null | null |
quant-ph
| null |
We show that it is possible to associate univocally with each given solution
of the time-dependent Schroedinger equation a particular phase flow ("quantum
flow") of a non-autonomous dynamical system. This fact allows us to introduce a
definition of chaos in quantum dynamics (quantum chaos), which is based on the
classical theory of chaos in dynamical systems. In such a way we can introduce
quantities which may be appelled "Quantum Lyapunov Exponents". Our approach
applies to a non-relativistic quantum-mechanical system of n charged particles;
in the present work numerical calculations are performed only for the hydrogen
atom. In the computation of the trajectories we first neglect the spin
contribution to chaos, then we consider the spin effects in quantum chaos. We
show how the quantum Lyapunov exponents can be evaluated and give several
numerical results which describe some properties found in the present approach.
Although the system is very simple and the classical counterpart is regular,
the most non-stationary solutions of the corresponding Schroeodinger equation
are "chaotic" according to our definition.
|
[
{
"version": "v1",
"created": "Wed, 19 Jul 2006 18:05:31 GMT"
},
{
"version": "v2",
"created": "Tue, 16 Jan 2007 10:35:08 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Falsaperla",
"P.",
""
],
[
"Fonte",
"G.",
""
],
[
"Salesi",
"G.",
""
]
] |
quant-ph/0607134
|
Alexander Pechen
|
Alexander Pechen
|
White noise approach to the low density limit of a quantum particle in a
gas
|
This preprint is a minor modification of the published paper
|
QP-PQ: Quantum Probability and White Noise Analysis, Vol. 18, Eds.
M. Sch\"urmann and U. Franz, (2005) 428--447
| null | null |
quant-ph math-ph math.MP
| null |
The white noise approach to the investigation of the dynamics of a quantum
particle interacting with a dilute and in general non-equilibrium gaseous
environment in the low density limit is outlined. The low density limit is the
kinetic Markovian regime when only pair collisions (i.e., collisions of the
test particle with one particle of the gas at one time moment) contribute to
the dynamics. In the white noise approach one first proves that the appropriate
operators describing the gas converge in the sense of appropriate matrix
elements to certain operators of quantum white noise. Then these white noise
operators are used to derive quantum white noise and quantum stochastic
equations describing the approximate dynamics of the total system consisting of
the particle and the gas. The derivation is given ab initio, starting from the
exact microscopic quantum dynamics. The limiting dynamics is described by a
quantum stochastic equation driven by a quantum Poisson process. This equation
then applied to the derivation of quantum Langevin equation and linear
Boltzmann equation for the reduced density matrix of the test particle. The
first part of the paper describes the approach which was developed by L.
Accardi, I.V. Volovich and the author and uses the Fock-antiFock (or GNS)
representation for the CCR algebra of the gas. The second part presents the
approach to the derivation of the limiting equations directly in terms of the
correlation functions, without use of the Fock-antiFock representation. This
approach simplifies the derivation and allows to express the strength of the
quantum number process directly in terms of the one-particle $S$-matrix.
|
[
{
"version": "v1",
"created": "Wed, 19 Jul 2006 20:07:45 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Pechen",
"Alexander",
""
]
] |
quant-ph/0607135
|
Deborah Watson
|
M. Dunn, D.K. Watson, and J.G. Loeser
|
N identical particles under quantum confinement: A many-body dimensional
perturbation theory approach II, the lowest-order wave function II
| null | null | null | null |
quant-ph
| null |
In this paper, the second in a series of two, we complete the derivation of
the lowest-order wave function of a dimensional perturbation theory (DPT)
treatment for the N-body quantum-confined system. Taking advantage of the
symmetry of the zeroth-order configuration, we use group theoretic techniques
and the FG matrix method from quantum chemistry to obtain analytic results for
frequencies and normal modes. This method directly accounts for each two-body
interaction, rather than an average interaction so that even lowest-order
results include beyond-mean-field effects. It is thus appropriate for the study
of both weakly and strongly interacting systems and the transition between
them. While previous work has focused on energies, lowest-order wave functions
yield important information such as the nature of excitations and expectation
values of physical observables at low orders including density profiles. Higher
orders in DPT also require as input the zeroth-order wave functions. In the
earlier paper we presented a program for calculating the analytic normal-mode
coordinates of the large-D system and illustrated the procedure by deriving the
two simplest normal modes. In this paper we complete this analysis by deriving
the remaining, and more complex, normal coordinates of the system.
|
[
{
"version": "v1",
"created": "Wed, 19 Jul 2006 20:09:49 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Dunn",
"M.",
""
],
[
"Watson",
"D. K.",
""
],
[
"Loeser",
"J. G.",
""
]
] |
quant-ph/0607136
|
Marcus Aguiar de
|
L.C. dos Santos and M.A.M. de Aguiar
|
Coherent State Path Integrals in the Weyl Representation
|
23 pages
|
J. Phys. A: Math. Gen. 39 (2006) 13465-13482.
|
10.1088/0305-4470/39/43/006
| null |
quant-ph
| null |
We construct a representation of the coherent state path integral using the
Weyl symbol of the Hamiltonian operator. This representation is very different
from the usual path integral forms suggested by Klauder and Skagerstan in
\cite{Klau85}, which involve the normal or the antinormal ordering of the
Hamiltonian. These different representations, although equivalent quantum
mechanically, lead to different semiclassical limits. We show that the
semiclassical limit of the coherent state propagator in Weyl representation is
involves classical trajectories that are independent on the coherent states
width. This propagator is also free from the phase corrections found in
\cite{Bar01} for the two Klauder forms and provides an explicit connection
between the Wigner and the Husimi representations of the evolution operator.
|
[
{
"version": "v1",
"created": "Thu, 20 Jul 2006 00:34:29 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Santos",
"L. C. dos",
""
],
[
"de Aguiar",
"M. A. M.",
""
]
] |
quant-ph/0607137
|
Leonid A. Krivitsky
|
G. Brida, M.V. Chekhova, M. Genovese, L.A. Krivitsky
|
Dispersion spreading of polarization-entangled states of light and
two-photon interference
|
Extended version of our recent PRL paper. Submitted to PRA
|
Phys. Rev. A 75, 015801 (2007)
|
10.1134/S1054660X0704041X
| null |
quant-ph
| null |
We study the interference structure of the second-order intensity correlation
function for polarization-entangled two-photon light obtained from type-II
collinear frequency-degenerate spontaneous parametric down-conversion (SPDC).
The structure is visualised due to the spreading of the two-photon amplitude as
two-photon light propagates through optical fibre with group-velocity
dispersion (GVD). Because of the spreading, polarization-entangled Bell states
can be obtained without any birefringence compensation at the output of the
nonlinear crystal; instead, proper time selection of the intensity correlation
function is required. A birefringent material inserted at the output of the
nonlinear crystal (either reducing the initial o-e delay between the oppositely
polarized twin photons or increasing this delay) leads to a more complicated
interference structure of the correlation function.
|
[
{
"version": "v1",
"created": "Thu, 20 Jul 2006 08:23:13 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Brida",
"G.",
""
],
[
"Chekhova",
"M. V.",
""
],
[
"Genovese",
"M.",
""
],
[
"Krivitsky",
"L. A.",
""
]
] |
quant-ph/0607138
|
N. L. Harshman
|
N. L. Harshman
|
Continuous-Discrete Entanglement: An Example with Non-Relativistic
Particles
|
9 pages, zero figures. v.2. corrects typos and clarifies notion of
shape-like entanglement. v.3. more of the same type of corrections
|
QIC 3 (2007) 273-280
| null | null |
quant-ph
| null |
This article discusses entanglement between two subsystems, one with discrete
degrees of freedom and the other with continuous degrees of freedom. The
overlap integral between continuous variable wave functions emerges as an
important parameter to characterize this kind entanglement. ``Beam-like''
entanglement and ``shape-like'' entanglement are contrasted. One example of
this kind of entanglement is between between the spin degrees of freedom and
the momentum degrees of freedom for a non-relativistic particle. This
intraparticle entanglement is Galilean invariant.
|
[
{
"version": "v1",
"created": "Thu, 20 Jul 2006 08:43:08 GMT"
},
{
"version": "v2",
"created": "Mon, 27 Nov 2006 20:20:50 GMT"
},
{
"version": "v3",
"created": "Wed, 24 Jan 2007 14:40:05 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Harshman",
"N. L.",
""
]
] |
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