# Matt's arXiv selection: week ending 28th September 2007.

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Sun, 14 Oct 2007 13:06:52 +1000 (EST)

The following message was sent to the matts_arxiv list by Matthew Davis <mdavis_at_physics.uq.edu.au>

Almost caught up... 26 new preprints and 11 replacments this week.

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arXiv:0709.3381
Date: Fri, 21 Sep 2007 12:26:12 GMT (34kb,D)

Title: Generalized ABCD propagation for interacting atomic clouds
Authors: F. Impens and Ch. J. Bord\'e
Categories: cond-mat.soft cond-mat.other
Comments: 10 pages, 2 figures
\\
We present a generalization of the atom optics ABCD formalism which
encapsulates atomic interactions in the aberationless approximation.
Interactions are modelled through an effective atom-optical lens term
determined perturbatively from the linear evolution. We apply this approach to
the determination of interaction effects in a free-falling cloud and to the
derivation of a stability condition for a matter-wave cavity.
\\ ( http://arxiv.org/abs/0709.3381 , 34kb)
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arXiv:0709.3392
Date: Fri, 21 Sep 2007 10:26:52 GMT (14kb)

Title: Optimally localized Wannier functions for quasi one-dimensional
nonperiodic insulators
Authors: H. D. Cornean, A. Nenciu and G. Nenciu
Categories: cond-mat.other
Comments: 16 pages, submitted
\\
It is proved that for general, not necessarily periodic quasi one dimensional
systems, the band position operator corresponding to an isolated part of the
energy spectrum has discrete spectrum and its eigenfunctions have the same
spatial localization as the corresponding spectral projection.
As a consequence, an eigenbasis of the band position operator provides a
basis of optimally localized (generalized) Wannier functions for quasi one
dimensional systems. If the system has some translation symmetries (e.g. usual
translations, screw transformations), they are "inherited" by the Wannier
basis.
\\ ( http://arxiv.org/abs/0709.3392 , 14kb)
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arXiv:0709.3310
Date: Thu, 20 Sep 2007 21:59:38 GMT (575kb)

Title: Final Report on ECCS/NSF Workshop on Quantum, Molecular and High
Performance Modeling and Simulation for Devices and Systems (QMHP)
Authors: Jonathan P. Dowling, Gerhard Klimeck
Categories: quant-ph
Comments: 42 pages, NSF Workshop on Quantum Molecular and High Performance
Modeling and Simulations for Devices and Systems (QMHP), 16-17 April 2007,
Arlington VA
\\
The National Science Foundation has identified a new thrust area in Quantum,
Molecular and High Performance Modeling and Simulation for Devices and Systems
(QMHP) in its core program. The main purpose of this thrust area is to capture
scientific opportunities that result from new fundamental cross-cutting
research involving three core research communities: (1) experts in modeling and
simulation of electronic devices and systems; (2) high performance computing
relevant to devices and systems; and (3) the quantum many-body principles
relevant to devices and systems. ECCS is especially interested in learning how
work in these areas could enable whole new classes of systems or devices,
beyond what is already under development in existing mainstream research. The
workshop helped identify technical areas that will enable fundamental
breakthroughs in the future. Modeling and simulation in the electronics and
optoelectronics areas, in general, have already resulted in important
fundamental scientific understanding and advances in design and development of
devices and systems. With the increasing emphasis on the next generation of
devices and systems at the nano, micro, and macro scales and the
interdisciplinary nature of the research, it is imperative that we explore new
mathematical models and simulation techniques. This workshop report provides a
better understanding of unmet emerging new opportunities to improve modeling,
simulation and design techniques for hybrid devices and systems. The purpose
the QMHP workshop was to define the field and strengthen the focus of the
thrust. The ultimate goal of the workshop was to produce a final report (this
document) that will be posted on the web so that the NSF can use it to guide
reviewers and researchers in this field.
\\ ( http://arxiv.org/abs/0709.3310 , 575kb)
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arXiv:0709.3335
Date: Fri, 21 Sep 2007 14:23:09 GMT (504kb)

Title: The quest for three-color entanglement: experimental investigation of
new multipartite quantum correlations
Authors: K. N. Cassemiro, A. S. Villar, M. Martinelli, and P. Nussenzveig
Categories: quant-ph
Comments: 10 pages, 5 figures, submitted to Opt. Express
\\
We experimentally investigate quadrature correlations between pump, signal,
and idler fields in an above-threshold optical parametric oscillator. We
observe new quantum correlations among the pump and signal or idler beams, as
well as among the pump and a combined quadrature of signal and idler beams. A
further investigation of unforeseen classical noise observed in this system is
presented, which hinders the observation of the recently predicted tripartite
entanglement. In spite of this noise, current results approach the limit
required to demonstrate three-color entanglement.
\\ ( http://arxiv.org/abs/0709.3335 , 504kb)
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arXiv:0709.3463
Date: Fri, 21 Sep 2007 15:32:52 GMT (113kb,D)

Title: Quantum Ratchets for Quantum Communication with Optical Superlattices
Authors: Oriol Romero-Isart and Juan Jose Garcia-Ripoll
Categories: quant-ph
Comments: 9 pages, 5 figures
\\
We propose to use a quantum ratchet to transport quantum information in a
chain of atoms trapped in an optical superlattice. The quantum ratchet is
created by a continuous modulation of the optical superlattice which is
periodic in time and in space. Though there is zero average force acting on the
atoms, we show that indeed the ratchet effect permits atoms on even and odd
sites to move along opposite directions. By loading the optical lattice with
two-level bosonic atoms, this scheme permits to perfectly transport a qubit or
entangled state imprinted in one or more atoms to any desired position in the
lattice. From the quantum computation point of view, the transport is achieved
by a smooth concatenation of perfect swap gates. We analyze setups with
noninteracting and interacting particles and in the latter case we use the
tools of optimal control to design optimal modulations. We also discuss the
feasibility of this method in current experiments.
\\ ( http://arxiv.org/abs/0709.3463 , 113kb)
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arXiv:0709.3331
Date: Fri, 21 Sep 2007 00:16:52 GMT (168kb)

Title: Parallel TREE code for two-component ultracold plasma analysis
Authors: Byoungseon Jeon, Joel D. Kress, Lee A. Collins and Niels
Gr{\o}nbech-Jensen
Categories: physics.comp-ph physics.plasm-ph
\\
The TREE method has been widely used for long-range interaction {\it N}-body
problems. We have developed a parallel TREE code for two-component classical
plasmas with open boundary conditions and highly non-uniform charge
distributions. The program efficiently handles millions of particles evolved
over long relaxation times requiring millions of time steps. Appropriate domain
decomposition and dynamic data management were employed, and large-scale
parallel processing was achieved using an intermediate level of granularity of
domain decomposition and ghost TREE communication. Even though the
computational load is not fully distributed in fine grains, high parallel
efficiency was achieved for ultracold plasma systems of charged particles. As
an application, we performed simulations of an ultracold neutral plasma with a
half million particles and a half million time steps. For the long temporal
trajectories of relaxation between heavy ions and light electrons, large
configurations of ultracold plasmas can now be investigated, which was not
possible in past studies.
\\ ( http://arxiv.org/abs/0709.3331 , 168kb)
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arXiv:0709.3740
Date: Mon, 24 Sep 2007 12:07:07 GMT (497kb)

Title: Staggered Vortex Superfluid of Ultracold Bosons in an Optical Lattice
Authors: Lih-King Lim, C. Morais Smith, Andreas Hemmerich
Categories: cond-mat.supr-con cond-mat.other
Comments: 4 pages, 3 figures
\\
We show that the dynamics of an ultracold bosonic gas loaded into a
two-dimensional square optical lattice with anisotropic and time-dependent
hopping terms can be described by a Bose-Hubbard model with an effective
staggered magnetic field. Besides the uniform superfluid and Mott insulating
phases, the zero-temperature phase diagram exhibits a novel kind of superfluid
phase, characterized by a quantized staggered rotational flux. This superfluid
condenses at finite momentum, a feature known from
Fulde-Ferrel-Larkin-Ovchinnikov phases of paired fermions.
\\ ( http://arxiv.org/abs/0709.3740 , 497kb)
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arXiv:0709.3768
Date: Mon, 24 Sep 2007 14:12:07 GMT (13kb)

Title: Thermalisation by a boson bath in a pure state
Authors: S. Camalet
Categories: cond-mat.mes-hall
\\
We consider a quantum system weakly coupled to a large heat bath of harmonic
oscillators. It is well known that such a boson bath initially at thermal
equilibrium thermalises the system. We show that assuming a priori an
equilibrium state is not necessary to obtain the thermalisation of the system.
We determine the complete Schr\"odinger time evolution of the subsystem of
interest for an initial pure product state of the composite system consisting
of the considered system and the bath. We find that the system relaxes into
canonical equilibrium for almost all initial pure bath states of
macroscopically well-defined energy. The temperature of the system asymptotic
thermal state is determined by the energy of the initial bath state as the
corresponding microcanonical temperature. Moreover, the time evolution of the
system is identical to the one obtained assuming that the boson bath is
initially at thermal equilibrium with this temperature. A significant part of
our approach is applicable to other baths and we identify the bath features
which are requisite for the thermalisation studied.
\\ ( http://arxiv.org/abs/0709.3768 , 13kb)
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arXiv:0707.2539
Date: Tue, 17 Jul 2007 15:15:12 GMT (100kb)

Title: Three-dimensional Monte Carlo simulations of the quantum linear
Boltzmann equation
Authors: Heinz-Peter Breuer and Bassano Vacchini
Categories: quant-ph cond-mat.stat-mech
Comments: 11 pages, revtex, 11 figures
Journal-ref: Phys. Rev. E 76 (2007) 036706
DOI: 10.1103/PhysRevE.76.036706
\\
Recently the general form of a translation-covariant quantum Boltzmann
equation has been derived which describes the dynamics of a tracer particle in
a quantum gas. We develop a stochastic wave function algorithm that enables
full three-dimensional Monte Carlo simulations of this equation. The simulation
method is used to study the approach to equilibrium for various scattering
cross sections and to determine dynamical deviations from Gaussian statistics
through an investigation of higher-order cumulants. Moreover, we examine the
loss of coherence of superpositions of momentum eigenstates and determine the
corresponding decoherence time scales to quantify the transition from quantum
to classical behavior of the state of the test particle.
\\ ( http://arxiv.org/abs/0707.2539 , 100kb)
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arXiv:0709.3780
Date: Mon, 24 Sep 2007 18:03:10 GMT (259kb)

Title: Order parameter for the dynamical phase transition in Bose-Einstein
condensates with topological modes
Authors: E. R. F. Ramos, L. Sanz, V.I. Yukalov and V. S. Bagnato
Categories: quant-ph
Journal-ref: Phys. Rev. A 76, 033608 (2007)
DOI: 10.1103/PhysRevA.76.033608
\\
In a trapped Bose-Einstein condensate, subject to the action of an
alternating external field, coherent topological modes can be resonantly
excited. Depending on the amplitude of the external field and detuning
parameter, there are two principally different regimes of motion, with mode
locking and without it. The change of the dynamic regime corresponds to a
dynamic phase transition. This transition can be characterized by an effective
order parameter defined as the difference between fractional mode populations
averaged over the temporal period of oscillations. The behavior of this order
parameter, as a function of detuning, pumping amplitude, and atomic
interactions is carefully analyzed. A special attention is payed to numerical
calculations for the realistic case of a quadrupole exciting field and the
system parameters accessible in current experiments.
\\ ( http://arxiv.org/abs/0709.3780 , 259kb)
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arXiv:0709.3842
Date: Mon, 24 Sep 2007 21:02:32 GMT (27kb)

Title: A nonlinear Ramsey interferometer operating beyond the Heisenberg limit
Authors: S. Choi and B. Sundaram
Categories: cond-mat.other
Comments: 4 figures. Submitted for publication
\\
We show that a dynamically evolving two-mode Bose-Einstein condensate (TBEC)
with an adiabatic, time-varying Raman coupling maps exactly onto a nonlinear
Ramsey interferometer that includes a nonlinear medium. Assuming a realistic
quantum state for the TBEC, namely the SU(2) coherent spin state, we find that
the measurement uncertainty of the path-difference'' phase shift scales as
the standard quantum limit (1/N^{1/2}) where N is the number of atoms, while
that for the interatomic scattering strength scales as 1/N^{7/5}, overcoming
the Heisenberg limit of 1/N.
\\ ( http://arxiv.org/abs/0709.3842 , 27kb)
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arXiv:0709.3888
Date: Tue, 25 Sep 2007 08:01:21 GMT (219kb,D)

Title: Fluctuation Theorems
Authors: E.M. Sevick, R. Prabhakar, Stephen R. Williams and Debra J. Searles
Categories: cond-mat.stat-mech
Comments: A review, submitted to Annual Reviews in Physical Chemistry, July
2007
\\
Fluctuation theorems, which have been developed over the past 15 years, have
resulted in fundamental breakthroughs in our understanding of how
irreversibility emerges from reversible dynamics, and have provided new
statistical mechanical relationships for free energy changes. They describe the
statistical fluctuations in time-averaged properties of many-particle systems
such as fluids driven to nonequilibrium states, and provide some of the very
few analytical expressions that describe nonequilibrium states. Quantitative
predictions on fluctuations in small systems that are monitored over short
periods can also be made, and therefore the fluctuation theorems allow
thermodynamic concepts to be extended to apply to finite systems. For this
reason, fluctuation theorems are anticipated to play an important role in the
design of nanotechnological devices and in understanding biological processes.
These theorems, their physical significance and results for experimental and
model systems are discussed.
\\ ( http://arxiv.org/abs/0709.3888 , 219kb)
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arXiv:0709.3900
Date: Tue, 25 Sep 2007 09:17:56 GMT (485kb)

Title: Nonlinear tunneling in two-dimensional lattices
Authors: V.A. Brazhnyi, V.V. Konotop, V. Kuzmiak, and V.S. Shchesnovich
Categories: cond-mat.other
Journal-ref: Phys. Rev. A 76, 023608 (2007)
\\
We present thorough analysis of the nonlinear tunneling of Bose-Einstein
condensates in static and accelerating two-dimensional lattices within the
framework of the mean-field approximation. We deal with nonseparable lattices
considering different initial atomic distributions in the highly symmetric
states. For analytical description of the condensate before instabilities are
developed, we derive several few-mode models, analyzing both essentially
nonlinear and quasi-linear regimes of tunneling. By direct numerical
simulations, we show that two-mode models provide accurate description of the
tunneling when either initially two states are populated or tunneling occurs
between two stable states. Otherwise a two-mode model may give only useful
qualitative hints for understanding tunneling but does not reproduce many
features of the phenomenon. This reflects crucial role of the instabilities
developed due to two-body interactions resulting in non-negligible population
of the higher bands. This effect becomes even more pronounced in the case of
accelerating lattices. In the latter case we show that the direction of the
acceleration is a relevant physical parameter which affects the tunneling by
changing the atomic rates at different symmetric states and by changing the
numbers of bands involved in the atomic transfer.
\\ ( http://arxiv.org/abs/0709.3900 , 485kb)
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arXiv:0709.4050
Date: Wed, 26 Sep 2007 04:26:57 GMT (358kb)

Title: Extended Gutzwiller Approximation for Inhomogenous System
Authors: Wing-Ho Ko, Cody P. Nave, Patrick A. Lee
Categories: cond-mat.str-el
Comments: 12 pages, 1 table, 6 figures
\\
The generalization of the Gutzwiller approximation to inhomogeneous systems
is considered, with extra spin-and-site-dependent fugacity factors included. It
is found that the inclusion of fugacity factors reconciles the seemingly
contradictory choices of Gutzwiller factors used in the literature. Moreover,
from the derivation of the Gutzwiller factors, it is shown that the Gutzwiller
approximation breaks the rotational symmetry of the trial wavefunctions, and
that different components of the spin-spin interaction need to be renormalized
differently under the approximation. Various schemes to restore the rotational
symmetry are discussed and are compared with results from variational
Monte-Carlo calculations for the two-dimensional square-lattice
antiferromagnet. Results along different paths within the full parameter space,
which corresponds to different choices of fugacity factors in the literature,
are also compared.
\\ ( http://arxiv.org/abs/0709.4050 , 358kb)
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arXiv:0709.4022 (*cross-listing*)
Date: Tue, 25 Sep 2007 19:55:07 GMT (17kb)

Title: The Lieb-Liniger Model as a Limit of Dilute Bosons in Three Dimensions
Authors: Robert Seiringer, Jun Yin
Categories: math-ph cond-mat.stat-mech math.MP
Comments: LaTeX2e, 19 pages
\\
We show that the Lieb-Liniger model for one-dimensional bosons with repulsive
$\delta$-function interaction can be rigorously derived via a scaling limit
from a dilute three-dimensional Bose gas with arbitrary repulsive interaction
potential of finite scattering length. For this purpose, we prove bounds on
both the eigenvalues and corresponding eigenfunctions of three-dimensional
bosons in strongly elongated traps and relate them to the corresponding
quantities in the Lieb-Liniger model. In particular, if both the scattering
length $a$ and the radius $r$ of the cylindrical trap go to zero, the
Lieb-Liniger model with coupling constant $g \sim a/r^2$ is derived. Our bounds
are uniform in $g$ in the whole parameter range $0\leq g\leq \infty$, and apply
to the Hamiltonian for three-dimensional bosons in a spectral window of size
$\sim r^{-2}$ above the ground state energy.
\\ ( http://arxiv.org/abs/0709.4022 , 17kb)
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arXiv:0709.4109
Date: Wed, 26 Sep 2007 15:20:43 GMT (41kb)

Title: Enhanced Deflection of Light Ray by Atomic Ensemble on Coherent
Population Oscillation
Authors: Jing Lu, Lan Zhou, Le-Man Kuang, C. P. Sun
Categories: quant-ph
Comments: 7pages, 2 figures
\\
In recent experiments[e.g., Nature Physics \textbf{2}, 332 (2006)], the
enhancing light deflection in an atomic ensemble due to inhomogeneous fields is
shown by the electromagnetically induced transparency (EIT) based mechanism. In
this paper, we explore an different mechanism for the similar phenomenon of the
enhanced light deflection. This mechanism is based on the coherent population
oscillation, which results in the hole burning of the dispersion windows. The
medium causing the deflection of probe light is an ensemble of two level atoms
manipulated by a strong controlled field on the two photon resonances. In the
large detuning condition, the response of the medium to the pump field and
signal field is obtained with steady state approximation. And it is found that
after the probe field traveling across the medium, the signal ray bends due to
the spatial-dependent profile of the control beam.
\\ ( http://arxiv.org/abs/0709.4109 , 41kb)
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arXiv:0709.4151
Date: Wed, 26 Sep 2007 13:52:30 GMT (25kb)

Title: Universal description of the rotational-vibrational spectrum of three
particles with zero-range interactions
Authors: O. I. Kartavtsev and A. V. Malykh
Categories: physics.atom-ph
\\
A comprehensive universal description of the rotational-vibrational spectrum
for two identical particles of mass $m$ and the third particle of the mass
$m_1$ in the zero-range limit of the interaction between different particles is
given for arbitrary values of the mass ratio $m/m_1$ and the total angular
momentum $L$. If the two-body scattering length is positive, a number of
vibrational states is finite for $L_c(m/m_1) \le L \le L_b(m/m_1)$, zero for
$L>L_b(m/m_1)$, and infinite for $L<L_c(m/m_1)$. If the two-body scattering
length is negative, a number of states is either zero for $L \ge L_c(m/m_1)$ or
infinite for $L<L_c(m/m_1)$. For a finite number of vibrational states, all the
binding energies are described by the universal function $\epsilon_{LN}(m/m_1) = {\cal E}(\xi, \eta)$, where $\xi=\displaystyle\frac{N-1/2}{\sqrt{L(L + 1)}}$,
$\eta=\displaystyle\sqrt{\frac{m}{m_1 L (L + 1)}}$,and $N$ is the vibrational
quantum number. This scaling dependence is in agreement with the numerical
calculations for $L > 2$ and only slightly deviates from those for $L = 1, 2$.
The universal description implies that the critical values $L_c(m/m_1)$ and
$L_b(m/m_1)$ increase as $0.401 \sqrt{m/m_1}$ and $0.563 \sqrt{m/m_1}$,
respectively, while a number of vibrational states for $L \ge L_c(m/m_1)$ is
within the range $N \le N_{max} \approx 1.1 \sqrt{L(L+1)}+1/2$.
\\ ( http://arxiv.org/abs/0709.4151 , 25kb)
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arXiv:0709.4024
Date: Tue, 25 Sep 2007 20:00:08 GMT (7kb)

Title: Shut up and calculate
Authors: Max Tegmark (MIT)
Categories: physics.pop-ph hep-th
Comments: This is the "director's cut" version of the September 15 2007 New
Scientist cover story. For references, see the "full strength" version at
arXiv:0704.0646
\\
I advocate an extreme "shut-up-and-calculate" approach to physics, where our
external physical reality is assumed to be purely mathematical. This brief
essay motivates this "it's all just equations" assumption and discusses its
implications.
\\ ( http://arxiv.org/abs/0709.4024 , 7kb)
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arXiv:0709.4335
Date: Thu, 27 Sep 2007 09:15:13 GMT (33kb)

Title: Localization of an impurity particle on a boson Mott insulator
background
Authors: Sevilay Sevincli, R. O. Umucalilar, M. O. Oktel
Categories: cond-mat.other
Comments: 11 pages, 9 figures
\\
We investigate the behavior of a single particle hopping on a three
dimensional cubic optical lattice in the presence of a Mott insulator of bosons
in the same lattice. We calculate the critical interaction strength between the
impurity and background bosons, beyond which there is bound state (polaron)
formation. We give exact results in the limit of a perfect Mott insulator,
where polaron formation is equivalent to impurity localization. We calculate
the effects of lattice anisotropy, higher impurity bands, and fluctuations of
the Mott insulator on the localization threshold. We argue that our results can
be checked experimentally by RF spectroscopy of impurity particles.
\\ ( http://arxiv.org/abs/0709.4335 , 33kb)
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arXiv:0709.4357
Date: Thu, 27 Sep 2007 11:00:03 GMT (368kb)

Title: Collective excitations of BEC under anharmonic trap position jittering
Authors: F. Kh. Abdullaev, R. M. Galimzyanov and Kh. N. Ismatullaev
Categories: cond-mat.other
Comments: This paper contains a manuscript - SolAnJPB.tex and figures (fig1 -
fig1a.eps and fig1b.eps, fig2 - fig2.eps, fig3 - fig3a.eps and fig3b.eps,
fig4 - fig4a.eps and fig4b.eps). The manuscript has been prepared using
LATEX2e with the iopart class and the figures in encapsulated PostScript
\\
Collective excitations of a Bose-Einstein condensate under periodic
oscillations of a quadratic plus quartic trap position has been studied. A
coupled set of variational equations is derived for the width and the
condensate wave function center. Analytical expressions for the growth of
oscillation amplitudes in the resonance case are derived. It is shown that
jittering of an anharmonic trap position can cause double resonance of the BEC
width and the center of mass oscillation in the wide range of the BEC
parameters values. The predictions of variational approach are confirmed by
full numerical simulations of the 1D GP equation.
\\ ( http://arxiv.org/abs/0709.4357 , 368kb)
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arXiv:0709.4424
Date: Thu, 27 Sep 2007 15:28:37 GMT (66kb)

Title: Fermi-Fermi Mixtures in the Strong Attraction Limit
Authors: M. Iskin and C. A. R. Sa de Melo
Categories: cond-mat.supr-con cond-mat.other
Comments: 12 Pages, 6 Figures and 1 Table
\\
The phase diagrams of low density Fermi-Fermi mixtures with equal or unequal
masses and equal or unequal populations are described at zero and finite
temperatures in the strong attraction limit. In this limit, the Fermi-Fermi
mixture can be described by a weakly interacting Bose-Fermi mixture, where the
bosons correspond to Feshbach molecules and the fermions correspond to excess
atoms. First, we discuss the three and four fermion scattering processes, and
use the exact boson-fermion and boson-boson scattering lengths to generate the
phase diagrams in terms of the underlying fermion-fermion scattering length. In
three dimensions, in addition to the normal and uniform superfluid phases, we
find two stable non-uniform states corresponding to (1) phase separation
between pure unpaired (excess) and pure paired fermions (molecular bosons); and
(2) phase separation between pure excess fermions and a mixture of excess
fermions and molecular bosons. Lastly, we also discuss the effects of the
trapping potential in the density profiles of condensed and non-condensed
molecular bosons, and excess fermions at zero and finite temperatures, and
discuss possible implications of our findings to experiments involving mixtures
of ultracold fermions.
\\ ( http://arxiv.org/abs/0709.4424 , 66kb)
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arXiv:0709.4436
Date: Thu, 27 Sep 2007 15:58:36 GMT (135kb)

Title: The Amplitude Mode in the Quantum Phase Model
Authors: S.D. Huber, B. Theiler, E. Altman, and G. Blatter
Categories: cond-mat.other
Comments: 4 pages, 3 figures
\\
We derive the collective low energy excitations of the quantum phase model of
interacting lattice bosons within the superfluid state using a dynamical
variational approach. We recover the well known sound (or Goldstone) mode and
derive a gapped (Higgs type) mode that was overlooked in previous studies of
the quantum phase model. This mode is relevant to ultracold atoms in a strong
optical lattice potential. We predict the signature of the gapped mode in
lattice modulation experiments and show how it evolves with increasing
interaction strength.
\\ ( http://arxiv.org/abs/0709.4436 , 135kb)
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arXiv:0709.4260
Date: Wed, 26 Sep 2007 20:41:40 GMT (138kb)

Title: Geometric resonance cooling of polarizable particles in an optical
waveguide
Authors: G. Szirmai, P. Domokos
Categories: quant-ph
\\
In the radiation field of an optical waveguide, the Rayleigh scattering of
photons is shown to result in a strongly velocity-dependent force on atoms. The
pump field, which is injected in the fundamental branch of the waveguide, is
favorably scattered by a moving atom into one of the transversely excited
branches of propagating modes. All fields involved are far detuned from any
resonances of the atom. For a simple polarizable particle, a linear friction
force coefficient comparable to that of cavity cooling can be achieved.
\\ ( http://arxiv.org/abs/0709.4260 , 138kb)
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arXiv:0709.4268
Date: Thu, 27 Sep 2007 00:00:35 GMT (53kb)

Title: Coherence lifetimes of excitations in an atomic condensate due to the
thin spectrum
Authors: T. Birol, T. Dereli, \"O. E. M\"ustecapl{\i}o\u{g}lu, L. You
Categories: quant-ph
\\
We study the quantum coherence properties of a finite sized atomic condensate
using a toy-model and the thin spectrum model formalism. The decoherence time
for a condensate in the ground state, nominally taken as a variational symmetry
breaking state, is investigated for both zero and finite temperatures. We also
consider the lifetimes for Bogoliubov quasi-particle excitations, and contrast
them to the observability window determined by the ground state coherence time.
The lifetimes are shown to exhibit a general characteristic dependence on the
temperature, determined by the thin spectrum accompanying the spontaneous
symmetry breaking ground state.
\\ ( http://arxiv.org/abs/0709.4268 , 53kb)
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arXiv:0709.4320
Date: Thu, 27 Sep 2007 06:53:20 GMT (248kb)

Title: Experimental observation of the Anderson transition with atomic matter
waves
Authors: Julien Chab\'e (PhLAM, CERLA), Gabriel Lemari\'e (LKB - Jussieu),
Beno\^it Gr\'emaud (LKB - Jussieu), Dominique Delande (LKB - Jussieu), Pascal
Szriftgiser (PhLAM, CERLA), Jean Claude Garreau (PhLAM, CERLA)
Categories: quant-ph
Comments: 16 pages, 4 color figures, word 2003 document
Proxy: ccsd hal-00175097
\\
Phase transitions are major phenomena in physics. Of particular interest in
modern physics is the metal-insulator Anderson transition in disordered
systems, ultimately due to the interplay between quantum interference and
disorder. We present the first experimental observation of the Anderson
transition using atomic matter waves. The metal-insulator transition plays a
central role in the study of quantum disordered systems, and has been extended
from its original solid-state scope to many different fields, including
dynamical systems, electromagnetic radiation, acoustics, biology and even
cosmology. Many studies have also pointed out strong analogies between cold
atoms trapped in optical lattices and condensed matter. Using an atom-optics
system formally equivalent to the 3D Anderson model we unambiguously
demonstrate the Anderson transition. Sensitive measurements of the atomic
dynamics and the use of finite-size scaling techniques make it possible to
extract both the critical disorder strength and the critical exponent of the
transition. In doing so, we make use of the physical concepts underlying phase
transition phenomena: universality classes (i.e., the insensitivity of the
critical phenomena to the microscopic properties of the system) and
renormalization (which describes the scaling laws in the vicinity of the
transition).
\\ ( http://arxiv.org/abs/0709.4320 , 248kb)
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\\
arXiv:0709.4349
Date: Thu, 27 Sep 2007 10:08:29 GMT (13kb)

Title: Bose-Einstein condensate in a harmonic trap with an eccentric dimple
potential
Authors: Haydar Uncu, Devrim Tarhan, Ersan Demiralp, Ozgur E. Mustecaplioglu
Categories: quant-ph
Comments: 12 pages, 5 figures, International Laser Physics Workshop. to be
appear in Laser Physics
\\
We investigate Bose-Einstein condensation of noninteracting gases in a
harmonic trap with an off-center dimple potential. We specifically consider the
case of a tight and deep dimple potential which is modelled by a point
interaction. This point interaction is represented by a Dirac delta function.
The atomic density, chemical potential, critical temperature and condensate
fraction, the role of the relative depth and the position of the dimple
potential are analyzed by performing numerical calculations.
\\ ( http://arxiv.org/abs/0709.4349 , 13kb)
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The replacements:

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\\
arXiv:0707.1205
replaced with revised version Fri, 21 Sep 2007 18:32:56 GMT (389kb)

Title: Non-Equilibrium Dynamics and Superfluid Ring Excitations in Binary
Bose-Einstein Condensates
Authors: K. M. Mertes, J. Merrill, R. Carretero-Gonzalez, D. J. Frantzeskakis,
P. G. Kevrekidis, and D. S. Hall
Categories: cond-mat.other
Comments: 4 pages, 3 figures (low res.), to appear in PRL
\\ ( http://arxiv.org/abs/0707.1205 , 389kb)
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\\
arXiv:cond-mat/0702555
replaced with revised version Sat, 22 Sep 2007 21:36:20 GMT (36kb)

Title: Bold Diagrammatic Monte Carlo: When Sign Problem is Welcome
Authors: Nikolay Prokof'ev and Boris Svistunov
Categories: cond-mat.stat-mech cond-mat.str-el
Comments: 4 pages, 2 figures, revtex4
\\ ( http://arxiv.org/abs/cond-mat/0702555 , 36kb)
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\\
arXiv:0705.4352
replaced with revised version Mon, 24 Sep 2007 11:41:06 GMT (277kb)

Title: Signal of Bose condensation in an optical lattice at finite temperature
Authors: W. Yi, G.-D. Lin, and L.-M. Duan
Categories: cond-mat.other
Comments: 4 pages, 2 figures, replaced with the published version
Journal-ref: Phys. Rev. A 76, 031602(R) (2007)
DOI: 10.1103/PhysRevA.76.031602
\\ ( http://arxiv.org/abs/0705.4352 , 277kb)
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\\
arXiv:0707.4259
replaced with revised version Mon, 24 Sep 2007 18:04:29 GMT (23kb)

Title: Fermi-Polaron: Diagrammatic Monte Carlo for Divergent Sign-Alternating
Series
Authors: Nikolay Prokof'ev and Boris Svistunov
Categories: cond-mat.stat-mech
Comments: 4 pages, 7 figures
\\ ( http://arxiv.org/abs/0707.4259 , 23kb)
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\\
arXiv:0709.2425
replaced with revised version Sat, 22 Sep 2007 12:16:31 GMT (28kb)

Title: Detection of acceleration radiation in a Bose-Einstein condensate
Authors: A. Retzker, J. I. Cirac, M. B. Plenio, B. Reznik
Categories: quant-ph
Comments: 5 pages, 3 figures
\\ ( http://arxiv.org/abs/0709.2425 , 28kb)
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\\
arXiv:cond-mat/0701484
replaced with revised version Wed, 26 Sep 2007 11:58:21 GMT (57kb)

Title: Finite temperature phase diagram of a polarized Fermi gas in an optical
lattice
Authors: T.K. Koponen, T. Paananen, J.-P. Martikainen, and P. Torma
Categories: cond-mat.supr-con cond-mat.other
Journal-ref: Phys. Rev. Lett. 99, 120403 (2007)
\\ ( http://arxiv.org/abs/cond-mat/0701484 , 57kb)
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\\
arXiv:0705.1502
replaced with revised version Wed, 26 Sep 2007 19:06:09 GMT (34kb)

Title: Three fermions in a box at the unitary limit: universality in a lattice
model
Authors: Ludovic Pricoupenko (LPTMC), Yvan Castin (LKB - Lhomond)
Categories: cond-mat.other
Proxy: ccsd hal-00145589
\\ ( http://arxiv.org/abs/0705.1502 , 34kb)
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\\
arXiv:0706.4123
replaced with revised version Wed, 26 Sep 2007 13:39:20 GMT (808kb)

Title: Level crossing in the three-body problem for strongly interacting
fermions in a harmonic trap
Authors: J. P. Kestner, L.-M. Duan
Categories: cond-mat.other
Comments: 5 pages, 6 figures, typos corrected, references added
Journal-ref: Phys. Rev. A 76, 033611 (2007)
DOI: 10.1103/PhysRevA.76.033611
\\ ( http://arxiv.org/abs/0706.4123 , 808kb)
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\\
arXiv:0709.1444
replaced with revised version Wed, 26 Sep 2007 07:56:42 GMT (64kb)

Title: Fermi-Bose transformation for the time-dependent Lieb-Liniger gas
Authors: H. Buljan, R. Pezer, T. Gasenzer
Categories: cond-mat.other
Comments: 4+ pages, 1 figure; added references
\\ ( http://arxiv.org/abs/0709.1444 , 64kb)
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\\
arXiv:quant-ph/0702067
replaced with revised version Wed, 26 Sep 2007 11:06:23 GMT (92kb,D)

Title: Spatial Entanglement From Off-Diagonal Long Range Order in a BEC
Authors: Libby Heaney, Janet Anders, Dagomir Kaszlikowski, Vlatko Vedral
Categories: quant-ph
Comments: 7 pages, 3 figures. Extended from 4 to 7 pages. More detailed
derivations of key formula. Extended introduction and background. Results
remain unchanged
\\ ( http://arxiv.org/abs/quant-ph/0702067 , 92kb)
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\\
arXiv:0705.1324
replaced with revised version Thu, 27 Sep 2007 17:39:25 GMT (340kb)

Title: Bright-Dark Soliton Complexes in Spinor Bose-Einstein Condensates
Authors: H.E. Nistazakis, D.J. Frantzeskakis, P.G. Kevrekidis, B.A. Malomed, R.
Carretero-Gonzalez
Categories: cond-mat.other
Comments: 10 pages, 4 figures. Submitted to PRA, May 2007
\\ ( http://arxiv.org/abs/0705.1324 , 340kb)
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Till next time,
Matt.

--
=========================================================================
Dr M. J. Davis,               Senior Lecturer in Physics
School of Physical Sciences,  email: mdavis_at_physics.uq.edu.au
University of Queensland,     ph   : +61 7 334 69824
Brisbane, QLD 4072,           fax  : +61 7 336 51242
Australia.                    http://www.physics.uq.edu.au/people/mdavis/
=========================================================================
Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org
http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/
=========================================================================
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Received on Sun Oct 14 2007 - 13:06:52 EST

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