Matt's arXiv selection: week ending 2 November 2007.

From: Matthew Davis <>
Date: Fri, 23 Nov 2007 14:46:30 +1000

The following message was sent to the matts_arxiv list by Matthew Davis <>

At least I haven't fallen further behind this week... 34 new preprints and 9

Date: Fri, 26 Oct 2007 11:21:05 GMT (896kb)

Title: Kosterlitz-Thouless transition of the quasi two-dimensional trapped Bose
Authors: Markus Holzmann and Werner Krauth
Categories: cond-mat.stat-mech
Comments: 4 pages, 4 figures
   We present Quantum Monte Carlo calculations with up to N=576000 interacting
bosons in a quasi two-dimensional trap geometry closely related to recent
experiments with atomic gases. The density profile of the gas and the
non-classical moment of inertia yield intrinsic signatures for the
Kosterlitz--Thouless transition temperature T_KT. From the reduced one-body
density matrix, we compute the condensate fraction, which is quite large for
small systems. It decreases slowly with increasing system sizes, vanishing in
the thermodynamic limit. We interpret our data in the framework of the
local-density approximation, and point out the relevance of our results for the
analysis of experiments.
\\ ( , 896kb)
Date: Fri, 26 Oct 2007 13:06:53 GMT (254kb)

Title: Control of Interaction-Induced Dephasing of Bloch Oscillations
Authors: M. Gustavsson, E. Haller, M.J. Mark, J.G. Danzl, G. Rojas-Kopeinig,
   H.-C. Naegerl
Categories: cond-mat.other
Comments: 4 pages, 5 figures
   We report on the control of interaction-induced dephasing of Bloch
oscillations for an atomic Bose-Einstein condensate in an optical lattice under
the influence of gravity. When tuning the strength of the interaction towards
zero by means of a Feshbach resonance, the dephasing time is increased from a
few to more than twenty thousand Bloch oscillation periods. We quantify the
dephasing in terms of the width of the quasi-momentum distribution and measure
its dependence on time for different values of the scattering length.
Minimizing the dephasing allows us to realize a BEC-based atom interferometer
in the non-interacting limit. We use it for a precise determination of a
zero-crossing for the atomic scattering length and to observe collapse and
revivals of Bloch oscillations when the atomic sample is subject to a spatial
force gradient.
\\ ( , 254kb)
Date: Fri, 26 Oct 2007 14:28:30 GMT (405kb)

Title: Creation of robust entangled states and new resources for
   measurement-based quantum computation using optical superlattices
Authors: B. Vaucher, A. Nunnenkamp, and D. Jaksch
Categories: cond-mat.other
Comments: 23 pages, 6 figures, IOP style
   We investigate how to create robust entangled states of ultracold atoms
trapped in optical lattices by dynamically manipulating the shape of the
lattice potential. We consider an additional potential (the superlattice) that
allows both the splitting of each site into a double well potential, and the
control of the height of potential barrier between sites. We use superlattice
manipulations to perform entangling operations between neighbouring qubits
encoded on the Zeeman levels of the atoms without having to perform transfers
between the different vibrational states of the atoms. We show how to use
superlattices to engineer robust many-body entangled states. Also, we present a
method to realize a 2D resource for measurement-based quantum computing via
Bell-pair measurements that is resilient to collective dephasing noise. We
analyze measurement networks that allow the execution of quantum algorithms
while maintaining the resilience properties of the system throughout the
\\ ( , 405kb)
Date: Fri, 26 Oct 2007 16:05:43 GMT (241kb)

Title: Atom interferometry with a weakly-interacting Bose Einstein condensate
Authors: Marco Fattori, Chiara D'Errico, Giacomo Roati, Matteo Zaccanti, Mattia
   Jona-Lasinio, Michele Modugno, Massimo Inguscio and Giovanni Modugno
Categories: cond-mat.other
Comments: 5 pages, 5 figures
   We demonstrate the operation of an atom interferometer based on a weakly
interacting Bose-Einstein condensate. We strongly reduce the interaction
induced decoherence that usually limits interferometers based on trapped
condensates by tuning the s-wave scattering length almost to zero via a
magnetic Feshbach resonance. We employ a $^{39}$K condensate trapped in an
optical lattice, where Bloch oscillations are forced by gravity. With a control
of the scattering length better that 0.1 $a_0$ we achieve coherence times of
several hundreds of ms. The micrometric sizes of the atomic sample make our
sensor an ideal candidate for measuring forces with high spatial resolution.
Our technique can be in principle extended to other measurement schemes opening
new possibilities in the field of trapped atom interferometry.
\\ ( , 241kb)
Date: Tue, 18 Sep 2007 02:35:47 GMT (312kb)

Title: Spin squeezing and maximal-squeezing time
Authors: Guang-Ri Jin and Sang Wook Kim
Categories: quant-ph cond-mat.other
Comments: 7 pages, 5 figures, 1 table. Resubmitted to Phys. Rev. A
Journal-ref: Phys. Rev. A76, 043621(2007)
DOI: 10.1103/PhysRevA.76.043621
   Spin squeezing of a nonlinear interaction model with Josephson-like coupling
is studied to obtain time scale of maximal squeezing. Based upon two exactly
solvable cases for two and three particles, we find that the maximal-squeezing
time depends on the level spacing between the ground state and its next
neighbor eigenstate.
\\ ( , 312kb)
Date: Sun, 30 Sep 2007 06:48:05 GMT (122kb)

Title: Storage of spin squeezing in a two-component Bose-Einstein condensate
Authors: Guang-Ri Jin and Sang Wook Kim
Categories: quant-ph cond-mat.other
Comments: 10 pages, 5 figures. This version is slightly different from the one
   published in Phys. Rev. Lett
Journal-ref: Phys. Rev. Lett.99, 170405 (2007)
DOI: 10.1103/PhysRevLett.99.170405
   Efficient control of spin squeezing in a two-component Bose-Einstein
Condensate is studied by rapidly turning-off the external field at a time that
maximal spin squeezing appears. We show that strong reduction of spin
fluctuation can be maintained in a nearly fixed direction for a long time. We
explain the underlying physics unambiguously, and present analytical
expressions of the maximal-squeezing time.
\\ ( , 122kb)
Date: Wed, 24 Oct 2007 08:16:00 GMT (171kb)

Title: Control of Optical Dynamic Memory Capacity of an Atomic Bose-Einstein
Authors: Devrim Tarhan, Alphan Sennaroglu, Ozgur E. Mustecaplioglu
Categories: quant-ph cond-mat.other
Comments: 4 figures, 9 pages
   Light storage in an atomic Bose-Einstein condensate is one of the most
practical usage of these coherent atom-optical systems. In order to make them
even more practical, it is necessary to enhance our ability to inject multiple
pulses into the condensate. In this paper, we report that dispersion of pulses
injected into the condensate can be compensated by optical nonlinearity. In
addition, we will present a brief review of our earlier results in which
enhancement of light storage capacity is accomplished by utilizing multi-mode
light propagation or choosing an optimal set of experimental parameters.
\\ ( , 171kb)
Date: Thu, 25 Oct 2007 13:21:46 GMT (236kb)

Title: Loschmidt cooling by time reversal of atomic matter waves
Authors: J. Martin, B. Georgeot, D. L. Shepelyansky (CNRS, Toulouse)
Categories: cond-mat.stat-mech nlin.CD quant-ph
Comments: revtex 4 pages, 5 figs, research at
   We propose an experimental scheme which allows to realize approximate time
reversal of matter waves of ultracold atoms in the regime of quantum chaos. We
show that a significant fraction of the atoms return back to their original
state, being at the same time cooled down by two orders of magnitude. We give a
theoretical description of this effect supported by extensive numerical
simulations. The proposed scheme can be implemented with existing experimental
\\ ( , 236kb)
Date: Fri, 26 Oct 2007 22:14:19 GMT (445kb)

Title: Phase Coherence and Superfluid-Insulator Transition in a Disordered
   Bose-Einstein Condensate
Authors: Yong P. Chen, J. Hitchcock, D. Dries, M. Junker, C. Welford, R. G.
Categories: cond-mat.other
Comments: 5 pages, 4 figures
   We have studied the effects of a disordered optical potential on the
transport and phase coherence of a Bose-Einstein condensate (BEC) of 7Li atoms.
At moderate disorder strengths (V_D), we observe inhibited transport and
damping of dipole excitations, while in time-of-flight images, random but
reproducible interference patterns are observed. The interference reflects
phase coherence in the disordered BEC and is interpreted as speckle for matter
waves. At higher V_D, the interference contrast diminishes as the BEC fragments
into multiple pieces with little phase coherence.
\\ ( , 445kb)
Date: Sat, 27 Oct 2007 07:10:53 GMT (10kb)

Title: Dynamical symmetry in spinor Bose-Einstein condensates
Authors: Shun Uchino, Takaharu Otsuka, Masahito Ueda
Categories: cond-mat.other
Comments: 18 pages
   We demonstrate that dynamical symmetry plays a crucial role in determining
the structure of the eigenspectra of spinor Bose-Einstein condensates (BECs).
In particular, the eigenspectra of spin-1 and spin-2 BECs in the single-mode
approximation are shown to be completely determined by dynamical symmetries,
where a spin-2 BEC corresponds to the U(5) limit of the interacting boson model
in nuclear physics. The eigenspectrum of a spin-3 BEC is solved exactly for a
specific class of coupling constants, while it is shown that dynamical symmetry
alone is not enough to determine the spectrum for arbitrary coupling constants.
\\ ( , 10kb)
Date: Sat, 27 Oct 2007 12:18:05 GMT (132kb)

Title: Phase space deformation of a trapped dipolar Fermi gas
Authors: Takahiko Miyakawa, Takaaki Sogo, Han Pu
Categories: cond-mat.other
Comments: 5 pages, 5 figures
   We consider a system of quantum degenerate spin polarized fermions in a
harmonic trap at zero temperature, interacting via dipole-dipole forces. We
introduce a variational Wigner function to describe the deformation and
compression of the Fermi gas in phase space and use it to examine the stability
of the system. We emphasize the important roles played by the Fock exchange
term of the dipolar interaction which results in a non-spherical Fermi surface.
\\ ( , 132kb)
Date: Sun, 28 Oct 2007 14:53:54 GMT (36kb)

Title: BCS-BEC crossover in a strongly correlated Fermi gas
Authors: S. G. Bhongale, M. R. Goosen, and S.J.J.M.F. Kokkelmans
Categories: cond-mat.mes-hall
Comments: 4 pages, 3 figures
   We study the BCS-BEC crossover in the strongly correlated regime of an
ultra-cold rotating two component Fermi gas. Strong correlations are shown to
generate an additional long-range interaction which results in a modified
crossover region compared to the non-rotating situation. The two-particle
correlation function reveals a smooth crossover between the s-wave paired
fermionic fractional quantum Hall state and the bosonic Laughlin state.
\\ ( , 36kb)
Date: Sun, 28 Oct 2007 23:01:48 GMT (16kb)

Title: Phase diagram of a Bose gas near a wide Feshbach resonance
Authors: Lan Yin
Categories: cond-mat.other cond-mat.stat-mech cond-mat.str-el cond-mat.supr-con
Comments: 4 pages, 4 figures
   In this paper, we study the phase diagram of a homogeneous Bose gas with a
repulsive interaction near a wide Feshbach resonance at zero temperature. The
Bose-Einstein-condensation (BEC) state of atoms is a metastable state. When the
scattering length $a$ exceeds a critical value depending on the atom density
$n$, $na^3>0.035$, the molecular excitation energy is imaginary and the atomic
BEC state is dynamically unstable against molecule formation. The BEC state of
diatomic molecules has lower energy, where the atomic excitation is gapped and
the molecular excitation is gapless. However when the scattering length is
above another critical value, $na^3>0.0164$, the molecular BEC state becomes a
unstable coherent mixture of atoms and molecules.
\\ ( , 16kb)
Date: Mon, 29 Oct 2007 16:59:57 GMT (629kb)

Title: Bose-Einstein condensates of atoms with arbitrary spin
Authors: P. Van Isacker (GANIL), S. Heinze
Categories: cond-mat.other
Comments: Journal of Physics A, in press
Proxy: ccsd in2p3-00183262
Report-no: GANIL P 07 20
   We show that the ground state of a Bose-Einstein condensate of atoms with
hyperfine spin f = 2 can be either spin aligned, condensed into pairs of atoms
coupled to F = 0, or condensed into triplets of atoms coupled to F = 0. The
complete phase diagram is constructed for f = 2 and the generic properties of
the phase diagram are obtained for f > 2.
\\ ( , 629kb)
Date: Mon, 29 Oct 2007 16:09:03 GMT (1484kb)

Title: Exploring Exotic Superfluidity of Polarized Ultracold Fermions in
   Optical Lattices
Authors: Y. Chen, Z. D. Wang, F. C. Zhang, and C. S. Ting
Categories: cond-mat.supr-con
Comments: 5 pages, 4 figures
   We explore theoretically the novel superfluidity of harmonically-trapped
polarized ultracold fermionic atoms in a two-dimensional (2D) optical lattice
by solving the Bogoliubov-de Gennes equations. The pairing amplitude is found
to oscillate along the radial direction at low particle density and along the
angular direction at high density. The former is consistent with the existing
experiments and the latter is a newly predicted
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, which can be tested in
\\ ( , 1484kb)
Date: Mon, 29 Oct 2007 19:28:37 GMT (84kb)

Title: An Atom Laser is not monochromatic
Authors: S. Choi, D. Stromberg, and B. Sundaram
Categories: cond-mat.other
Comments: 4 figures. Submitted for publication
   We study both numerically and analytically the possibility of using an
adiabatic passage control method to construct a Mach-Zehnder interferometer
(MZI) for Bose-Einstein condensates (BECs) in the time domain, in exact
one-to-one correspondence with the traditional optical MZI that involves two
beam splitters and two mirrors. The interference fringes one obtains from such
a minimum-disturbance set up clearly demonstrates that, fundamentally, an atom
laser is not monochromatic due to interatomic interactions. We also consider
how the amount of entanglement in the system correlates to the interference
\\ ( , 84kb)
Date: Mon, 29 Oct 2007 11:52:40 GMT (173kb)

Title: Ground-State Properties for Coupled Bose-Einstein Condensates inside a
   Cavity Quantum Electrodynamics
Authors: Gang Chen, Zidong Chen, and J.-Q.Liang
Categories: quant-ph
Report-no: Department of Physics, Shaoxing College of Arts and Sciences,
   Shaoxing 312000, People's Republic of China
Journal-ref: EPL, 80 (2007) 40004
   We analytically investigate the ground-state properties of two-component
Bose-Einstein condensates with few &#8312;&#8311;Rb atoms inside a high-quality
cavity quantum electrodynamics. In the SU(2) representation for atom, this
quantum system can be realized a generalized Dicke model with a quadratic term
arising from the interatomic interactions, which can be controlled
experimentally by Feshbach resonance technique. Moreover, this weak
interspecies interaction can give rise to an important zero-temperature quantum
phase transition from the normal to the superradiant phases, where the atomic
ensemble in the normal phase is collectively unexcited while is macroscopically
excited with coherent radiations in the superradiant phase. Finally, we propose
to observe this predicted quantum phase transition by measuring the direct and
striking signatures of the photon field in terms of a heterodyne detector out
of the cavity.
\\ ( , 173kb)
Date: Mon, 29 Oct 2007 14:51:22 GMT (32kb)

Title: Exciton-Polariton scattering for defect detection in cold atom Optical
Authors: Hashem Zoubi, and Helmut Ritsch
Categories: quant-ph
Comments: 9 pages, 10 figures
   We study the effect of defects in the Mott insulator phase of ultracold atoms
in an optical lattice on the dynamics of resonant excitations. Defects, which
can either be empty sites in a Mott insulator state with one atom per site or a
singly occupied site for a filling factor two, change the dynamics of Frenkel
excitons and cavity polaritons. While the vacancies in first case behave like
hard sphere scatters for excitons, singly occupied sites in the latter case can
lead to attractive or repulsive scattering potentials. We suggest cavity
polaritons as observation tool of such defects, and show how the scattering can
be controlled in changing the exciton-photon detuning. In the case of
asymmetric optical lattice sites we present how the scattering effective
potential can be detuned by the cavity photon polarization direction, with the
possibility of a crossover from a repulsive into an attractive potential.
\\ ( , 32kb)
Date: Mon, 29 Oct 2007 16:55:26 GMT (125kb)

Title: A Weyl function approach to matter-wave coherence and Talbot-Lau effects
Authors: Saijun Wu, Pierre S. Striehl, Mara G. Prentiss
Categories: physics.atom-ph
Comments: 38 pages, 17 figures
   Weyl functions conveniently describe the evolution of wave coherences in
periodic or quadratic potentials. In this work we use Weyl functions to study
the ``Talbot-Lau effect'' in a time-domain matter-wave interferometer. A
``displacement diagram'' is introduced to analyze and calculate the matter-wave
interference for an atomic cloud in a quadratic potential that interacts with a
sequence of short optical standing wave pulses producing an atomic grating
echo. Unlike previous treatments, this new approach allows the atomic ensemble
to have an arbitrary initial phase-space distribution, and the standing wave
grating vectors to span three dimensions. Several examples are discussed to
illustrate the convenience of the diagrammatic technique including the
following: a two-dimensional Talbot-Lau effect, the shift in the echo time and
the recoil phase for the interferometer perturbed by a quadratic potential; and
the realization of a time-domain ``Lau effect'' using a pulsed harmonic
potential. The diagrammatic technique is applicable to diffraction gratings
with arbitrary grating transmission functions. We conclude the paper with a
general discussion on the Weyl function representations of matter-wave
coherence, and discuss a conservation law that distinguishes decoherence
effects from dephasing effects.
\\ ( , 125kb)
Date: Mon, 29 Oct 2007 14:47:24 GMT (57kb)

Title: Light propagation in atomic Mott Insulators
Authors: Francesco Bariani, Iacopo Carusotto
Categories: physics.optics physics.atom-ph
   We study radiation-matter interaction in a system of ultracold atoms trapped
in an optical lattice in a Mott insulator phase. We develop a fully general
quantum model, and we perform calculations for a one-dimensional geometry at
normal incidence. Both two- and three-level $\Lambda$ atomic configurations are
studied. The polariton dispersion and the reflectivity spectra are
characterized in the different regimes, for both semi-infinite and finite-size
geometries. We apply this model to propose a photon energy lifter experiment: a
device which is able to shift the carrier frequency of a slowly travelling
wavepacket without affecting the pulse shape nor its coherence.
\\ ( , 57kb)
Date: Tue, 30 Oct 2007 05:01:10 GMT (142kb)

Title: Vortex lattice transitions in cyclic spinor condensates
Authors: Ryan Barnett, Subroto Mukerjee, Joel E. Moore
Categories: cond-mat.other
Comments: 4 pages, 2 figures
   We study the energetics of vortices and vortex lattices produced by rotation
in the cyclic phase of F=2 spinor Bose condensates. In addition to the familiar
triangular lattice predicted by Tkachenko for $^4$He, many more complex
lattices appear in this system as a result of the spin degree of freedom. In
particular, we predict a magnetic-field-driven transition from a triangular
lattice to a honeycomb lattice. Other transitions and lattice geometries are
driven at constant field by changes in the temperature-dependent ratio of
charge and spin stiffnesses, including a transition through an aperiodic vortex
\\ ( , 142kb)
Date: Tue, 30 Oct 2007 11:06:58 GMT (392kb)

Title: Quantum matter wave dynamics with moving mirrors
Authors: A. del Campo, J. G. Muga, M. Kleber
Categories: quant-ph
Comments: 5.2 pages, 6 figures
   When a stationary reflecting wall acting as a perfect mirror for an atomic
beam with well defined incident velocity is suddenly removed, the density
profile develops during the time evolution an oscillatory pattern known as
diffraction in time. The interference fringes are suppressed or their
visibility is diminished by several effects such as averaging over a
distribution of incident velocities, apodization of the aperture function,
atom-atom interactions, imperfect reflection or environmental noise. However,
when the mirror moves with finite velocity along the direction of propagation
of the beam, the visibility of the fringes is enhanced. For mirror velocities
below beam velocity, as used for slowing down the beam, the matter wave splits
into three regions separated by space-time points with classical analogues. For
mirror velocities above beam velocity a visibility enhancement occurs without a
classical counterpart. When the velocity of the beam approaches that of the
mirror the density oscillations rise by a factor 1.8 over the stationary value.
\\ ( , 392kb)
Date: Tue, 30 Oct 2007 12:09:27 GMT (29kb)

Title: Rydberg excitation of Bose-Einstein condensates
Authors: Rolf Heidemann, Ulrich Raitzsch, Vera Bendkowsky, Bj\"orn Butscher,
   Robert L\"ow, Tilman Pfau
Categories: quant-ph
Comments: 4 pages, 3 figures
   Rydberg atoms provide a wide range of possibilities to tailor interactions in
a quantum gas. Here we report on Rydberg excitation of Bose-Einstein condensed
87Rb atoms. The Rydberg fraction was investigated for various excitation times
and temperatures above and below the condensation temperature. The excitation
is locally blocked by the van der Waals interaction between Rydberg atoms to a
density-dependent limit. Therefore the abrupt change of the thermal atomic
density distribution to the characteristic bimodal distribution upon
condensation could be observed in the Rydberg fraction. The observed features
are reproduced by a simulation based on local collective Rydberg excitations.
\\ ( , 29kb)
Date: Tue, 30 Oct 2007 12:38:06 GMT (63kb,D)

Title: Scheme for implementing atomic multiport devices
Authors: Jacob A. Dunningham
Categories: quant-ph
Comments: 6 pages, 3 figures
   Multiport generalizations of beam splitters are an important tool in a range
of quantum information processing protocols. Networks for realising these
devices in optical systems, however, often involve complicated arrangements of
beam splitters and phase plates. This complexity threatens to undermine their
practicality for any more than a few input and output ports. Here we discuss
the case of multiport devices for atoms trapped in optical lattices. We
demonstrate simple schemes for implementing `tritters' and `quarters' and
discuss how these could be combined to create much larger devices with a
substantially lower overhead in atom-optical elements than other proposals.
\\ ( , 63kb)
Date: Wed, 31 Oct 2007 03:06:25 GMT (929kb,D)

Title: Two point correlations of a trapped interacting Bose gas at finite
Authors: A. Bezett, E. Toth, P. B. Blakie
Categories: cond-mat.other
Comments: 9 pages, 4 figures
   We develop a computationally tractable method for calculating correlation
functions of the finite temperature trapped Bose gas that includes the effects
of s-wave interactions. Our approach uses a classical field method to model the
low energy modes and treats the high energy modes using a Hartree-Fock
description. We present results of first and second order correlation
functions, in position and momentum space, for an experimentally realistic
system in the temperature range of $0.6T_c$ to $1.0T_c$. We also characterize
the spatial coherence length of the system. Our theory should be applicable in
the critical region where experiments are now able to measure first and second
order correlations.
\\ ( , 929kb)
Date: Wed, 31 Oct 2007 07:44:10 GMT (94kb)

Title: Anomalous behavior of the spatial pair correlation in a 1D Bose gas
Authors: A. G. Sykes, D. M. Gangardt, M. J. Davis, K. Viering, M. G. Raizen,
   and K. V. Kheruntsyan
Categories: cond-mat.other cond-mat.stat-mech
Comments: 4 pages, 2 figures
   We analytically calculate the nonlocal pair correlation function for an
interacting uniform 1D Bose gas at finite temperature. Our results span a
number of physical realms, including the weakly and strongly interacting
regimes. We find that under certain conditions the pair correlation may exhibit
a global maximum or minimum at a finite interparticle separations, implying
anomalous, non-monotonic behaviour and the existence of regimes with two
characteristic correlation lengths. We discuss possible experimental methods to
measure the nonlocal pair correlation function.
\\ ( , 94kb)
Date: Wed, 31 Oct 2007 09:03:59 GMT (185kb)

Title: Molecular Formations in Ultra-cold Mixture of Interacting/Noninteracting
   Atomic Gases
Authors: T. Nishimura, A. Matsumoto, H. Yabu
Categories: cond-mat.soft cond-mat.other
Comments: 41 pages, 17 figures
   Atom-molecule equilibrium for the molecular formation processes are discussed
for the boson-fermion, fermion-fermion and boson-boson mixtures of the
ultra-cold atomic gases in the framework of the quasichemical equilibrium
theory. After the general formulation is given for the molecular
formation/dissociation processes in the quasichemical equilibrium theory,
zero-temperature phase diagrams of the atom-molecule equilibrium states are
calculated analytically; they are shown to involve several phases depending on
the binding energy of the molecules, the molecular, mixed, and dissociated
ones. The temperature-dependences of the atom/molecule densities, which are
calculated numerically, are shown, and they give the finite-temperature phase
structures of the atom-molecule equilibrium in the mixtures. The transition
temperatures of the atom/molecule Bose-Einstein condensations are also
evaluated from these results. The quantum-statistical deviations of the law of
mass action in the atom-molecule equilibrium, which should be satisfied in the
mixtures of the classical Maxwell-Bolzmann gasses, are calculated, and the
difference in the different types of quantum-statistical particles, boson and
fermion, are clarified. Contributions of the interparticle interactions
(atom-atom, atom-molecule, and molecule-molecule) are formulated in the
mean-field approximation; the interaction effects are shown to be included in
the effective molecular binding energies through their linear
density-dependence. The zero-temperature phase diagrams are calculated for the
interacting mixtures, and they are shown to include the phases with coexistent
local-equilibrium states in the case of the strong repulsive interactions.
\\ ( , 185kb)
Date: Wed, 31 Oct 2007 18:24:30 GMT (761kb)

Title: Faraday waves in Bose-Einstein condensates
Authors: Alexandru I. Nicolin, R. Carretero-Gonzalez, and P.G. Kevrekidis
Categories: cond-mat.other
Comments: 10 pages, 9 figures, submitted to Phys. Rev. A
   Motivated by recent experiments on Faraday waves in Bose-Einstein condensates
we investigate both analytically and numerically the dynamics of cigar-shaped
Bose-condensed gases subject to periodic modulation of the strength of the
transverse confinement. We offer a fully analytical explanation of the observed
parametric resonance, based on a Mathieu-type analysis of the non-polynomial
Schr{\"o}dinger equation. The theoretical prediction for the pattern
periodicity versus the driving frequency is directly compared with the
experimental data, yielding good qualitative and quantitative agreement between
the two. These results are corroborated by direct numerical simulations of both
the one-dimensional non-polynomial Schr{\"o}dinger equation and of the fully
three-dimensional Gross-Pitaevskii equation.
\\ ( , 761kb)
Date: Wed, 31 Oct 2007 22:35:46 GMT (656kb)

Title: Superfluid and Mott Insulating shells of bosons in harmonically confined
   optical lattices
Authors: Kaushik Mitra, C. J. Williams and C. A. R. Sa de Melo
Categories: cond-mat.other
Comments: 11 pages, 9 figures,
   Weakly interacting atomic or molecular bosons in quantum degenerate regime
and trapped in harmonically confined optical lattices, exhibit a wedding cake
structure consisting of insulating (Mott) shells. It is shown that superfluid
regions emerge between Mott shells as a result of fluctuations due to finite
hopping. It is found that the order parameter equation in the superfluid
regions is not of the Gross-Pitaeviskii type except near the insulator to
superfluid boundaries. The excitation spectra in the Mott and superfluid
regions are obtained, and it is shown that the superfluid shells posses low
energy sound modes with spatially dependent sound velocity described by a local
index of refraction directly related to the local superfluid density. Lastly,
the Berezinskii-Kosterlitz-Thouless transition and vortex-antivortex pairs are
discussed in thin (wide) superfluid shells (rings) limited by three (two)
dimensional Mott regions.
\\ ( , 656kb)
Date: Thu, 1 Nov 2007 08:51:33 GMT (168kb)

Title: Dynamical Properties of a Rotating Bose-Einstein Condensate
Authors: Sebastian Kling and Axel Pelster
Categories: cond-mat.stat-mech
Comments: Author Information under
   Within a variational approach to solve the Gross-Pitaevskii equation we
investigate dynamical properties of a rotating Bose-Einstein condensate which
is confined in an anharmonic trap. In particular, we calculate the
eigenfrequencies of low-energy excitations out of the equilibrium state and the
aspect ratio of the condensate widths during the free expansion.
\\ ( , 168kb)
Date: Thu, 1 Nov 2007 16:21:55 GMT (62kb)

Title: Matter-wave vortices in cigar-shaped and toroidal waveguides
Authors: Luca Salasnich, Flavio Toigo (CNISM and CNR-INFM, Unita' di Padova,
   Dipartimento di Fisica "Galileo Galilei", Universita' di Padova, Via Marzolo
   8, Padova, Italy) and Boris A. Malomed (Department of Physical Electronics,
   School of Electrical Engineering, Faculty of Engineering, Tel Aviv
   University, Tel Aviv, Israel)
Categories: cond-mat.other
Comments: 6 pages, Physical Review A, in press
   We study vortical states in a Bose-Einstein condensate (BEC) filling a
cigar-shaped trap. An effective one-dimensional (1D) nonpolynomial Schroedinger
equation (NPSE) is derived in this setting, for the models with both repulsive
and attractive inter-atomic interactions. Analytical formulas for the density
profiles are obtained from the NPSE in the case of self-repulsion within the
Thomas-Fermi approximation, and in the case of the self-attraction as exact
solutions (bright solitons). A crucially important ingredient of the analysis
is the comparison of these predictions with direct numerical solutions for the
vortex states in the underlying 3D Gross-Pitaevskii equation (GPE). The
comparison demonstrates that the NPSE provides for a very accurate
approximation, in all the cases, including the prediction of the stability of
the bright solitons and collapse threshold for them. In addition to the
straight cigar-shaped trap, we also consider a torus-shaped configuration. In
that case, we find a threshold for the transition from the axially uniform
state, with the transverse intrinsic vorticity, to a symmetry-breaking pattern,
due to the instability in the self-attractive BEC filling the circular trap.
\\ ( , 62kb)
Date: Thu, 1 Nov 2007 18:36:30 GMT (110kb)

Title: Spectroscopy and the nature of the ground state of trapped polarized
Authors: Erich J. Mueller (Cornell)
Categories: cond-mat.other
Comments: 4 Pages, 2 figures, RevTeX4
   We show that bimodal radio frequency spectra universally arise at
intermediate temperatures in models of strongly interacting trapped Fermi
gases. The bimodality is independent of superfluidity or pseudogap physics,
depending only on the functional form of the equation of state -- which is
constrained by dimensional analysis at low temperatures and the virial
expansion at high temperatures. In addition to these model independent results,
we present a simple calculation of the radio frequency line-shape of a highly
polarized Fermi gas which uses energetic considerations to include final state
interactions. While this model only qualitatively captures the line-shapes
observed in the experiments, it provides a conceptually clean and powerful
technique for estimating the energy scales and how they vary with experimental
\\ ( , 110kb)
Date: Wed, 20 Jun 2007 20:03:04 GMT (378kb)

Title: Molecular Dipolar Crystals as High Fidelity Quantum Memory for Hybrid
   Quantum Computing
Authors: P. Rabl and P. Zoller
Categories: quant-ph cond-mat.other
Journal-ref: Phys. Rev. A 76, 042308 (2007)
   We study collective excitations of rotational and spin states of an ensemble
of polar molecules, which are prepared in a dipolar crystalline phase, as a
candidate for a high fidelity quantum memory. While dipolar crystals are formed
in the high density limit of cold clouds of polar molecules under 1D and 2D
trapping conditions, the crystalline structure protects the molecular qubits
from detrimental effects of short range collisions. We calculate the lifetime
of the quantum memory by identifying the dominant decoherence mechanisms, and
estimate their effects on gate operations, when a molecular ensemble qubit is
transferred to a superconducting strip line cavity (circuit QED). In the case
rotational excitations coupled by dipole-dipole interactions we identify
phonons as the main limitation of the life time of qubits. We study specific
setups and conditions, where the coupling to the phonon modes is minimized.
Detailed results are presented for a 1D dipolar chain.
\\ ( , 378kb)
Date: Tue, 31 Jul 2007 01:43:15 GMT (21kb)

Title: Correlations Functions of One-Dimensional Lieb-Liniger Anyons
Authors: Ovidiu I. Patu, Vladimir E. Korepin, Dmitri V. Averin
Categories: cond-mat.stat-mech quant-ph
Comments: 19 pages, RevTeX 4
   We have investigated the properties of a model of 1D anyons interacting
through a $\delta$-function repulsive potential. The structure of the
quasi-periodic boundary conditions for the anyonic field operators and the
many-anyon wavefunctions is clarified. The spectrum of the low-lying
excitations including the particle-hole excitations is calculated for periodic
and twisted boundary conditions. Using the ideas of the conformal field theory
we obtain the large-distance asymptotics of the density and field correlation
function at the critical temperature T=0 and at small finite temperatures. Our
expression for the field correlation function extends the results in the
literature obtained for harmonic quantum anyonic fluids.
\\ ( , 21kb)

The replacements:

replaced with revised version Fri, 26 Oct 2007 13:17:46 GMT (38kb)

Title: Effect of the lattice alignment on Bloch oscillations of a Bose-Einstein
   condensate in a square optical lattice
Authors: M.-C. Chung and A. R. Kolovsky
Categories: cond-mat.supr-con cond-mat.mes-hall
Comments: 4 pages, 3 figures
\\ ( , 38kb)
replaced with revised version Mon, 29 Oct 2007 14:36:52 GMT (644kb,D)

Title: Spatial noise correlations of a chain of ultracold fermions - A
   numerical study
Authors: Andreas Luscher, Andreas Laeuchli, Reinhard M. Noack
Categories: cond-mat.str-el
Comments: 12 pages, 7 figures
Journal-ref: Phys. Rev. A 76, 043614 (2007)
DOI: 10.1103/PhysRevA.76.043614
\\ ( , 644kb)
replaced with revised version Sun, 28 Oct 2007 23:01:34 GMT (181kb)

Title: Light scattering from ultracold atoms in optical lattices as an optical
   probe of quantum statistics
Authors: Igor B. Mekhov, Christoph Maschler, Helmut Ritsch
Categories: quant-ph physics.atom-ph physics.optics
Comments: 15 pages, 5 figures
\\ ( , 181kb)
replaced with revised version Mon, 29 Oct 2007 11:56:28 GMT (362kb)

Title: Entanglement renormalization in fermionic systems
Authors: G. Evenbly, G. Vidal
Categories: quant-ph
Comments: 5 pages, 4 figures Second appendix added
\\ ( , 362kb)
replaced with revised version Tue, 30 Oct 2007 12:25:23 GMT (75kb)

Title: Flow Equations for the BCS-BEC Crossover
Authors: S. Diehl, H. Gies, J. M. Pawlowski, C. Wetterich
Categories: cond-mat.supr-con cond-mat.stat-mech hep-ph quant-ph
Comments: 4 pages, 4 figures
Report-no: HD-THEP-07-02
Journal-ref: Phys. Rev. A 76, 021602(R) (2007)
\\ ( , 75kb)
replaced with revised version Tue, 30 Oct 2007 13:04:15 GMT (75kb)

Title: Renormalisation Flow and Universality for Ultracold Fermionic Atoms
Authors: S. Diehl, H. Gies, J. M. Pawlowski, C. Wetterich
Categories: cond-mat.supr-con cond-mat.stat-mech hep-th quant-ph
Comments: 19 pages, 3 figures, to be published in PRA
\\ ( , 75kb)
replaced with revised version Mon, 29 Oct 2007 22:44:15 GMT (382kb)

Title: Spin squeezing in optical lattice clocks via lattice-based QND
Authors: D. Meiser, Jun Ye, and M. J. Holland
Categories: quant-ph physics.atom-ph
Comments: Revised version with expanded introduction and discussion
\\ ( , 382kb)
replaced with revised version Wed, 31 Oct 2007 10:30:32 GMT (120kb)

Title: Dissipation of Quantum Turbulence in the Zero Temperature Limit
Authors: P. M. Walmsley, A. I. Golov, H. E. Hall, A. A. Levchenko and W. F.
Categories: cond-mat.other
Comments: 4 pages, 5 figures. Updated following referees comments
\\ ( , 120kb)
replaced with revised version Thu, 1 Nov 2007 18:54:59 GMT (343kb,D)

Title: Phase diagram of a two-component Fermi gas with resonant interactions
Authors: Yong-il Shin, Christian H. Schunck, Andre Schirotzek, Wolfgang
Categories: cond-mat.soft
Comments: 8 pages, 8 figures, reference added, typo corrected
\\ ( , 343kb)

Till next time,

Dr M. J. Davis,               Senior Lecturer in Physics
School of Physical Sciences,  email:
University of Queensland,     ph   : +61 7 334 69824
Brisbane, QLD 4072,           fax  : +61 7 336 51242
Matt's arXiv selection: weekly summary of cold-atom papers from
Legal stuff: Unless stated otherwise, this e-mail represents only the
views of the sender and not the views of the University of Queensland
Received on Wed Nov 28 2007 - 13:10:01 EST

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