# Matt's arXiv selection: week ending 29th June 2007

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Fri, 6 Jul 2007 14:24:35 +1000 (EST)

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

And you are almost up-to-date: 30 new preprints and 7 replacements last week:

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arXiv:0706.3280
Date: Fri, 22 Jun 2007 11:31:41 GMT (44kb)

Title: Theoretical background for observing ultra-slow microwaves in a
Bose-Einstein condensate of alkali atoms
Authors: Yuriy V. Slyusarenko and Andrey G. Sotnikov
Categories: cond-mat.stat-mech cond-mat.other
\\
We represent a new microscopic approach that allows studying the propagation
properties of microwaves in a Bose-Einstein condensate of alkali atoms. It is
assumed that the frequency of signal is tuned up to the transition between
hyperfine ground state levels of such atoms. Pulse slowing conditions
dependence on the system parameters is found. It is shown that the slowed
signal can propagate in mentioned system with rather small energy loss. Such
phenomenon is also studied in case of hyperfine levels Zeeman splitting. A
possibility of ultra-slow microwaves observing in a condensed gas of cesium
atoms is discussed.
\\ ( http://arxiv.org/abs/0706.3280 , 44kb)
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arXiv:0706.3360
Date: Fri, 22 Jun 2007 15:02:52 GMT (2160kb)

Title: Theory of ultracold Fermi gases
Authors: Stefano Giorgini, Lev P. Pitaevskii, Sandro Stringari
Categories: cond-mat.other
\\
The physics of quantum degenerate Fermi gases in uniform as well as in
harmonically trapped configurations is reviewed from a theoretical perspective.
Emphasis is given to the effect of interactions which play a crucial role,
bringing the gas into a superfluid phase at low temperature. In these dilute
systems interactions are characterized by a single parameter, the s-wave
scattering length, whose value can be tuned using an external magnetic field
near a Feshbach resonance. The BCS limit of ordinary Fermi superfluidity, the
Bose-Einstein condensation (BEC) of dimers and the unitary limit of large
scattering length are important regimes exhibited by interacting Fermi gases.
In particular the BEC and the unitary regimes are characterized by a high value
of the superfluid critical temperature, of the order of the Fermi temperature.
Different physical properties are discussed, including the density profiles and
the energy of the ground-state configurations, the momentum distribution, the
fraction of condensed pairs, collective oscillations and pair breaking effects,
the expansion of the gas, the main thermodynamic properties, the behavior in
the presence of optical lattices and the signatures of superfluidity, such as
the existence of quantized vortices, the quenching of the moment of inertia and
the consequences of spin polarization. Various theoretical approaches are
considered, ranging from the mean-field description of the BCS-BEC crossover to
non-perturbative methods based on quantum Monte Carlo techniques. A major goal
of the review is to compare the theoretical predictions with the available
experimental results.
\\ ( http://arxiv.org/abs/0706.3360 , 2160kb)
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arXiv:0706.3361
Date: Fri, 22 Jun 2007 15:46:08 GMT (398kb)

Title: Polarized States and Domain Walls in Spinor Bose-Einstein Condensates
Authors: H.E. Nistazakis, D.J. Frantzeskakis, P.G. Kevrekidis, B.A. Malomed, R.
Carretero-Gonzalez, and A.R. Bishop
Categories: cond-mat.other
Comments: 7 pages, 9 figures, submitted to Phys. Rev. A
\\
We study spin-polarized states and their stability in anti-ferromagnetic
states of spinor (F=1) quasi-one-dimensional Bose-Einstein condensates. Using
analytical approximations and numerical methods, we find various types of
polarized states, including: patterns of the Thomas-Fermi type; structures with
a pulse-shape in one component inducing a hole in the other components; states
with holes in all three components; and domain walls. A Bogoliubov-de Gennes
analysis reveals that families of these states contain intervals of a weak
oscillatory instability, except for the domain walls, which are always stable.
The development of the instabilities is examined by means of direct numerical
simulations.
\\ ( http://arxiv.org/abs/0706.3361 , 398kb)
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arXiv:0706.3376
Date: Fri, 22 Jun 2007 16:40:12 GMT (404kb)

Title: Quantum limited measurements of atomic scattering properties
Authors: A. M. Rey, L. Jiang and M. D. Lukin
Categories: cond-mat.other
\\
We propose a method to perform precision measurements of the interaction
parameters in systems of N ultra-cold spin 1/2 atoms. The spectroscopy is
realized by first creating a coherent spin superposition of the two relevant
internal states of each atom and then letting the atoms evolve under a
squeezing Hamiltonian. The non-linear nature of the Hamiltonian decreases the
fundamental limit imposed by the Heisenberg uncertainty principle to N^(-2), a
factor of N smaller than the fundamental limit achievable with non-interacting
atoms. We study the effect of decoherence and show that even with decoherence,
entangled states can outperform the signal to noise limit of non-entangled
states. We present two possible experimental implementations of the method
using Bose-Einstein spinor condensates and fermionic atoms loaded in optical
\\ ( http://arxiv.org/abs/0706.3376 , 404kb)
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arXiv:0706.3378
Date: Fri, 22 Jun 2007 17:13:16 GMT (735kb)

Title: Many-body protected entanglement generation in interacting spin systems
Authors: A. M. Rey, L. Jiang, M. Fleischhauer, E. Demler and M.D. Lukin
Categories: cond-mat.other
Comments: 11 pages, 7 figures. This paper is a longer version of the paper
cond-mat/0703108
\\
We discuss a method to achieve decoherence resistent entanglement generation
in two level spin systems governed by gapped and multi-degenerate Hamiltonians.
In such systems, while the large number of degrees of freedoms in the ground
state levels allows to create various quantum superposition, the energy gap
prevents decoherence as local excitations become energetically suppressed. We
apply the protected evolution to achieve decoherence resistent generation of
many particle GHZ states and show it can significantly increase the sensitivity
in frequency spectroscopy. We discuss how to engineer the desired many-body
protected manifold in two specific physical systems, trapped ions and neutral
atoms in optical lattices, and present simple expressions for the fidelity of
GHZ generation under non-ideal conditions.
\\ ( http://arxiv.org/abs/0706.3378 , 735kb)
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arXiv:0706.3300
Date: Fri, 22 Jun 2007 09:43:14 GMT (16kb)

Title: Trapped Bose gases with large positive scattering length
Authors: M. Th{\o}gersen, D.V. Fedorov, and A.S. Jensen
Categories: quant-ph
\\
We calculate the energy and the condensate fraction of a system of trapped
bosons interacting via a short-range two-body potential with positive
scattering length. The potential is attractive and has a two-body bound state.
When the scattering length is small compared to the trap length the system is
model independent: all potential models -- attractive, repulsive and zero-range
-- provide similar results. When the scattering length is large the attractive
model differs qualitatively from the repulsive and zero-range models. In this
regime the system with attractive potential becomes independent of the
scattering length, with both the energy and the condensate fraction converging
towards finite constants.
\\ ( http://arxiv.org/abs/0706.3300 , 16kb)
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arXiv:0706.3417
Date: Fri, 22 Jun 2007 22:54:40 GMT (28kb)

Title: Superfuid-insulator transitions at non-integer filling in optical
lattices of fermionic atoms
Authors: Chih-Chun Chien, Yan He, Qijin Chen, and K. Levin
Categories: cond-mat.other
\\
We determine the superfluid transition temperatures $T_c$ and the ground
states of the attractive Hubbard model and find new insulating phases
associated with non-integer filling at sufficiently strong pairing attraction
$|U|$. These states, distinct from the band and Mott insulating phases, derive
from pair localization; pair hopping at large $|U|$ and high densities is
impeded by inter-site, inter-pair repulsive interactions. The best way to
detect the breakdown of superfluidity is using fermionic optical lattices which
should reveal new forms of bosonic'' order, reflecting ground state pairing
without condensation.
\\ ( http://arxiv.org/abs/0706.3417 , 28kb)
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arXiv:0706.3458
Date: Mon, 25 Jun 2007 15:29:54 GMT (191kb)

Title: The Thermodynamic Casimir Effect in $^4$He Films near $T_\lambda$: Monte
Carlo Results
Authors: Alfred Hucht
Categories: cond-mat.stat-mech
\\
The universal finite-size scaling function of the critical Casimir force for
the three dimensional XY universality class with Dirichlet boundary conditions
is determined using Monte Carlo simulations. The results are in excellent
agreement with recent experiments on $^4$He Films at the superfluid transition
and with available theoretical predictions.
\\ ( http://arxiv.org/abs/0706.3458 , 191kb)
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arXiv:0706.3541
Date: Sun, 24 Jun 2007 23:36:46 GMT (43kb)

Title: Beyond Gross-Pitaevskii Mean Field Theory
Authors: N.P. Proukakis
Categories: cond-mat.other
Comments: Review Article (19 Pages) - To appear in 'Emergent Nonlinear
Phenomena in Bose-Einstein Condensates: Theory and Experiment', Edited by
P.G. Kevrekidis, D.J. Frantzeskakis and R. Carretero-Gonzalez (Springer
Verlag)
\\
A large number of effects related to the phenomenon of Bose-Einstein
Condensation (BEC) can be understood in terms of lowest order mean field
theory, whereby the entire system is assumed to be condensed, with thermal and
quantum fluctuations completely ignored. Such a treatment leads to the
Gross-Pitaevskii Equation (GPE) used extensively throughout this book. Although
this theory works remarkably well for a broad range of experimental parameters,
a more complete treatment is required for understanding various experiments,
including experiments with solitons and vortices. Such treatments should
include the dynamical coupling of the condensate to the thermal cloud, the
effect of dimensionality, the role of quantum fluctuations, and should also
describe the critical regime, including the process of condensate formation.
The aim of this Chapter is to give a brief but insightful overview of various
recent theories, which extend beyond the GPE. To keep the discussion brief,
only the main notions and conclusions will be presented. This Chapter
generalizes the presentation of Chapter 1, by explicitly maintaining
fluctuations around the condensate order parameter. While the theoretical
arguments outlined here are generic, the emphasis is on approaches suitable for
describing single weakly-interacting atomic Bose gases in harmonic traps.
Interesting effects arising when condensates are trapped in double-well
potentials and optical lattices, as well as the cases of spinor condensates,
and atomic-molecular coupling, along with the modified or alternative theories
needed to describe them, will not be covered here.
\\ ( http://arxiv.org/abs/0706.3541 , 43kb)
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arXiv:0706.3611
Date: Mon, 25 Jun 2007 10:21:02 GMT (225kb)

Title: Magnetic and superfluid phases of confined fermions in two-dimensional
optical lattices
Authors: Brian M. Andersen and G. M. Bruun
Categories: cond-mat.str-el cond-mat.supr-con
\\
We examine antiferromagnetic and d-wave superfluid phases of cold fermionic
atoms with repulsive interactions in a two-dimensional optical lattice combined
with a harmonic trapping potential. For experimentally realistic parameters,
the trapping potential leads to the coexistence of magnetic and superfluid
ordered phases with the normal phase. We study the intriguing shell structures
arising from the competition between the magnetic and superfluid order as a
function of the filling fraction. In certain cases antiferromagnetism induce
superfluidity by charge redistributions. We furthermore demonstrate how these
shell structures can be detected as distinct anti-bunching dips and pairing
peaks in the density-density correlation function probed in expansion
experiments.
\\ ( http://arxiv.org/abs/0706.3611 , 225kb)
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arXiv:0706.3617
Date: Mon, 25 Jun 2007 10:53:34 GMT (22kb)

Title: On microscopic theory of spin-S Bose-Einstein condensate in a magnetic
field
Authors: A.S. Peletminskii, S.V. Peletminskii, Yu.V. Slyusarenko
Categories: cond-mat.stat-mech
Journal-ref: Physica A 380, 202 (2007)
DOI: 10.1016/j.physa.2007.02.107
\\
The Bogoliubov model for weakly interacting Bose gas is extended to
Bose-Einstein condensation (BEC) of spin-S atoms in a magnetic field. Equation
for the vectorial order parameter valid at temperature $T\to 0$ is derived and
its particular solution is found. This solution corresponds to the formation of
BEC of atoms with a definite spin projection onto direction of a magnetic
field. We study the thermodynamic stability of the found solution and obtain
the expressions for low-lying collective modes.
\\ ( http://arxiv.org/abs/0706.3617 , 22kb)
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arXiv:0706.3686
Date: Mon, 25 Jun 2007 18:01:59 GMT (191kb)

Title: Non-equilibrium solid state quantum condensates: the effect of particle
flux on density profiles
Authors: Jonathan Keeling, Natalia G. Berloff
Categories: cond-mat.other
\\
For a spatially inhomogeneous quantum condensate in the presence of
incoherent particle injection and particle decay, persistent supercurrents
should exist, connecting regions of net gain with regions of net loss, leading
to modifications of the condensate density profile. We model trapped
exciton-polariton condensates by a complex Gross-Pitaevskii (a modified complex
Ginzburg-Landau) equation with pumping and decay and analyse the density and
supercurrents in the ground states. In particular, we show that in some
well-characterized parameter regime the ground state exhibits concentrated
narrow density peaks, as have been observed experimentally in polariton
condensates. We also consider vortex solutions of the system and demonstrate
the effects of superposition of supercurrents.
\\ ( http://arxiv.org/abs/0706.3686 , 191kb)
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arXiv:0706.3411
Date: Fri, 22 Jun 2007 21:13:30 GMT (483kb)

Title: Cavity QED with a Bose-Einstein condensate
Authors: Ferdinand Brennecke, Tobias Donner, Stephan Ritter, Thomas Bourdel,
Michael K\"ohl and Tilman Esslinger
Categories: quant-ph
\\
Cavity quantum electrodynamics (cavity QED) has proven to be exceedingly
successful in illuminating matter-light interaction and in providing concepts
for quantum information processing. Importantly, by using high-quality
resonators, a strong coupling regime can be reached in which atoms coherently
exchange a photon with one field mode many times before dissipation sets in.
This led to fundamental studies both with microwave and optical resonators. To
meet the challenges posed by quantum state engineering and quantum information
processing, recent experiments have focused on laser cooling and trapping atoms
inside an optical cavity. However, the tremendous advance in the control over
atomic gases achieved with Bose-Einstein condensation has so far not been
utilized for cavity QED. Here we report on the strong coupling of a
Bose-Einstein condensate to the quantized field of an ultrahigh-finesse optical
cavity and present a measurement of its eigenenergy spectrum. A quantitative
analysis reveals that due to the very strong collective coupling higher-order
transverse cavity modes have a significant influence on the spectrum. With this
experiment we enter a conceptually new regime of cavity QED where all atoms
occupy a single mode of a matter-wave field and couple identically to the light
field, sharing a single excitation. This opens possibilities ranging from
quantum communication to a wealth of new phenomena that can be expected in the
many-body physics of quantum gases with cavity mediated interaction.
\\ ( http://arxiv.org/abs/0706.3411 , 483kb)
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arXiv:0706.3649
Date: Mon, 25 Jun 2007 14:10:47 GMT (212kb)

Title: Vacuum Rabi splitting and intracavity dark state in a cavity-atoms
system
Authors: Gessler Hernandez, Jiepeng Zhang, and Yifu Zhu
Categories: physics.optics physics.atom-ph
\\
We report experimental measurements of the transmission spectrum of an
optical cavity coupled with cold Rb atoms. We observe the multi-atom vacuum
Rabi splitting of a composite cavity and atom system. When a coupling field is
applied to the atoms and induces the resonant two-photon Raman transition with
the cavity field in a Lamda-type three-level system, we observe a cavity
transmission spectrum with two vacuum Rabi sidebands and a central peak
representing the intracavity dark state. The central peak linewidth is
significantly narrowed by the dark-state resonance and its position is
insensitive to the frequency change of the empty cavity.
\\ ( http://arxiv.org/abs/0706.3649 , 212kb)
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arXiv:0706.3719
Date: Tue, 26 Jun 2007 17:05:08 GMT (83kb)

Title: Spectrum and thermal fluctuations of a microcavity polariton
Bose-Einstein condensate
Authors: Davide Sarchi, Vincenzo Savona
Categories: cond-mat.mes-hall cond-mat.other
\\
The Hartree-Fock-Popov theory of interacting Bose particles is developed, for
modeling exciton-polaritons in semiconductor microcavities undergoing
Bose-Einstein condensation. A self-consistent treatment of the linear
exciton-photon coupling and of the exciton non-linearity provides a thermal
equilibrium description of the collective excitation spectrum, of the polariton
energy shifts and of the phase diagram. Quantitative predictions support recent
experimental findings.
\\ ( http://arxiv.org/abs/0706.3719 , 83kb)
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arXiv:0706.3774
Date: Tue, 26 Jun 2007 08:39:16 GMT (69kb)

Title: Superfluid equation of state of dilute composite bosons
Authors: X. Leyronas and R. Combescot
Categories: cond-mat.stat-mech
\\
We present an exact theory of the BEC-BCS crossover in the BEC regime, which
treats explicitely dimers as made of two fermions. We apply our framework, at
zero temperature, to the calculation of the equation of state. We find that,
when expanding the chemical potential in powers of the density n up to the
Lee-Huang-Yang order, proportional to n^3/2, the result is identical to the one
of elementary bosons in terms of the dimer-dimer scattering length a_M, the
composite nature of the dimers appearing only in the next order term
proportional to n^2 .
\\ ( http://arxiv.org/abs/0706.3774 , 69kb)
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arXiv:0706.3799
Date: Tue, 26 Jun 2007 11:36:50 GMT (160kb)

Title: Mott insulators and correlated superfluids in ultracold Bose-Fermi
mixtures
Authors: F. Hebert, F. Haudin, L. Pollet and G.G. Batrouni
Categories: cond-mat.stat-mech
\\
We study the effects of interaction between bosons and fermions in a
Bose-Fermi mixtures loaded in an optical lattice. We concentrate on the
destruction of a bosonic Mott phase driven by repulsive interaction between
bosons and fermions. Once the Mott phase is destroyed, the system enters a
superfluid phase where the movements of bosons and fermions are correlated. We
show that this phase has simultaneously correlations reminiscent of a
conventional superfluid and of a pseudo-spin density wave order.
\\ ( http://arxiv.org/abs/0706.3799 , 160kb)
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arXiv:0706.3819
Date: Tue, 26 Jun 2007 12:50:55 GMT (13kb)

Title: Condensate Fraction of a Two-Dimensional Attractive Fermi Gas
Authors: Luca Salasnich (CNR-INFM and CNISM, Univ. Padova)
Categories: cond-mat.stat-mech cond-mat.supr-con
Comments: 4 pages, 2 figures, accepted for publication in Phys. Rev. A
\\
We investigate the Bose-Einstein condensation of fermionic pairs in a
two-dimensional uniform two-component Fermi superfluid obtaining an explicit
formula for the condensate density as a function of the chemical potential and
the energy gap. By using the mean-field extended BCS theory, we analyze, as a
function of the bound-state energy, the off-diagonal long-range order in the
crossover from the Bardeen-Cooper-Schrieffer (BCS) state of weakly-bound Cooper
pairs to the Bose-Einstein Condensate (BEC) of strongly-bound molecular dimers.
\\ ( http://arxiv.org/abs/0706.3819 , 13kb)
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arXiv:0706.3869
Date: Tue, 26 Jun 2007 16:39:01 GMT (81kb)

Title: An echo experiment in a strongly interacting Rydberg gas
Authors: Ulrich Raitzsch, Vera Bendkowsky, Rolf Heidemann, Bj\"orn Butscher,
Robert L\"ow, and Tilman Pfau
Categories: quant-ph
\\
Strong interactions in many-body quantum systems lead to quantum correlations
that typically make it very hard to follow their unitary, i.e., coherent
evolution and distinguish it from incoherent dynamics. When ground state atoms
are excited to a Rydberg state van der Waals interactions among them lead to a
strong suppression of excitation. Despite the strong interactions the evolution
can still be reversed by a simple phase shift in the excitation laser field if
the subsystems behave as effective two level systems, so called superatoms'
that show a collective dynamics. We experimentally prove the coherence of the
excitation in the strong blockade regime by applying an optical rotary echo'
technique, in analogy to a method known from nuclear magnetic resonance.
\\ ( http://arxiv.org/abs/0706.3869 , 81kb)
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arXiv:0706.3879
Date: Tue, 26 Jun 2007 17:46:11 GMT (154kb)

Title: Coherent Quantum Optical Control with Sub-wavelength Resolution
Authors: Alexey V. Gorshkov, Liang Jiang, Markus Greiner, Peter Zoller, and
Mikhail D. Lukin
Categories: quant-ph
\\
We suggest a new method for quantum optical control with nanoscale
resolution. Our method allows for coherent far-field manipulation of individual
quantum systems with spatial selectivity that is not limited by the wavelength
of radiation and can, in principle, approach a few nanometers. The selectivity
is enabled by the nonlinear atomic response, under the conditions of
Electromagnetically Induced Transparency, to a control beam with intensity
vanishing at a certain location. Practical performance of this technique and
its potential applications to quantum information science with cold atoms,
ions, and solid-state qubits are discussed.
\\ ( http://arxiv.org/abs/0706.3879 , 154kb)
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arXiv:0706.3946
Date: Wed, 27 Jun 2007 04:42:00 GMT (163kb)

Title: Phase diagram for a Bose-Einstein condensate moving in an optical
lattice
Authors: Jongchul Mun, Patrick Medley, Gretchen K. Campbell, Luis G. Marcassa,
David E. Pritchard, Wolfgang Ketterle
Categories: cond-mat.other
\\
The stability of superfluid currents in a system of ultracold bosons was
studied using a moving optical lattice. Superfluid currents in a very weak
lattice become unstable when their momentum exceeds 0.5 recoil momentum.
Superfluidity vanishes already for zero momentum as the lattice deep reaches
the Mott insulator(MI) phase transition. We study the phase diagram for the
disappearance of superfluidity as a function of momentum and lattice depth
between these two limits. Our phase boundary extrapolates to the critical
lattice depth for the superfluid-to-MI transition with 2% precision. When a
one-dimensional gas was loaded into a moving optical lattice a sudden
broadening of the transition between stable and unstable phases was observed.
\\ ( http://arxiv.org/abs/0706.3946 , 163kb)
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arXiv:0706.3995
Date: Wed, 27 Jun 2007 11:04:34 GMT (536kb)

Title: Dynamical instability and dispersion management of an attractive
condensate in an optical lattice
Authors: G. Barontini and M. Modugno
Categories: cond-mat.other
\\
We investigate the stability of an attractive Bose-Einstein condensate in a
moving 1D optical lattice in the presence of transverse confinement. By means
of a Bogoliubov linear stability analysis we find that the system is
dynamically unstable for low quasimomenta and becomes stable near the band
edge, in a specular fashion with respect to the repulsive case. For low
interactions the instability occurs via long wavelength excitations that are
not sufficient for spoiling the condensate coherence, producing instead an
oscillating density pattern both in real and momentum space. This behaviour is
illustrated by simulations for the expansion of the condensate in a moving
lattice.
\\ ( http://arxiv.org/abs/0706.3995 , 536kb)
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arXiv:0706.4000
Date: Wed, 27 Jun 2007 11:31:30 GMT (10kb)

Title: Effective field theory and cold Fermi gases near unitary limit
Authors: Boris Krippa
Categories: cond-mat.supr-con
\\
We study a dynamics of ultracold Fermi-gases near the unitary limit in the
framework of Effective Field Theory. It is shown that, while one can obtain a
reasonable description of the universal proportionality constant both in the
narrow and the broad Feshbach resonance limits, the reguirement of the
reparametrisation invariance leads to appearance of the three body forces
needed to cancel the otherwise arising off-shell uncertainties. The size of the
unsertainties is estimated.
\\ ( http://arxiv.org/abs/0706.4000 , 10kb)
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arXiv:0706.4041
Date: Wed, 27 Jun 2007 14:47:56 GMT (776kb)

Title: Matter-wave Interferometry with Phase Fluctuating Bose-Einstein
Condensates
Authors: G.-B. Jo, J.-H. Choi, C.A. Christensen, Y.-R. Lee, T.A. Pasquini, W.
Ketterle, and D.E. Pritchard
Categories: cond-mat.other
\\
Elongated Bose-Einstein condensates (BECs) exhibit strong spatial phase
fluctuations even well below the BEC transition temperature. We demonstrate
that atom interferometers using such condensates are robust against phase
fluctuations, i.e. the relative phase of the split condensate is reproducible
despite axial phase fluctuations. However, larger phase fluctuations limit the
coherence time, especially in the presence of some asymmetries in the two wells
of the interferometer.
\\ ( http://arxiv.org/abs/0706.4041 , 776kb)
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arXiv:0706.4085
Date: Wed, 27 Jun 2007 19:52:25 GMT (20kb)

Title: A new effective interaction for the trapped Fermi gas
Authors: Y. Alhassid, G.F. Bertsch, L. Fang
Categories: cond-mat.other
\\
We apply the configuration-interaction method to calculate the spectra of
two-component Fermi systems in a harmonic trap, studying the convergence of the
method at the unitary interaction limit. We find that for a fixed
regularization of the two-body interaction the convergence is exponential or
better in the truncation parameter of the many-body space. However, the
conventional regularization is found to have poor convergence in the
regularization parameter, with an error that scales as a low negative power of
this parameter. We propose a new regularization of the two-body interaction
that produces exponential convergence for systems of three and four particles.
From the systematics, we estimate the ground-state energy of the
four-particle system to be (5.05 +- 0.024)hbar omega.
\\ ( http://arxiv.org/abs/0706.4085 , 20kb)
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arXiv:0706.4123
Date: Thu, 28 Jun 2007 00:22:57 GMT (807kb)

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
\\
We present a solution of the three-fermion problem in a harmonic potential
across a Feshbach resonance. We compare the spectrum with that of the two-body
problem and show that it is energetically unfavorable for three fermions to
occupy one lattice site rather than two. We also demonstrate the existence of
an energy level crossing in the ground state with a symmetry change of its wave
function, suggesting the possibility of a phase transition for the
corresponding many-body case.
\\ ( http://arxiv.org/abs/0706.4123 , 807kb)
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arXiv:0706.4218
Date: Thu, 28 Jun 2007 12:55:05 GMT (169kb)

Title: Association of heteronuclear molecules in a harmonic oscillator well
Authors: Jesper Fevre Bertelsen and Klaus Molmer
Categories: cond-mat.other
\\
We describe the collisional interaction between two different atoms that are
trapped in a harmonic potential. The atoms are exposed to a magnetic field,
which is modulated in the vicinity of an s-wave Feshbach resonance, and we
study the formation of molecular bound states and excited states of the trapped
system with non-trivial angular correlations.
\\ ( http://arxiv.org/abs/0706.4218 , 169kb)
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arXiv:0706.4260
Date: Thu, 28 Jun 2007 15:46:41 GMT (384kb)

Title: Ultracold Bose gases in time-dependent 1D superlattices: response and
quasimomentum structure
Authors: Markus Hild, Felix Schmitt, Ilona T\"urschmann, Robert Roth
Categories: cond-mat.stat-mech
\\
The response of ultracold atomic Bose gases in time-dependent optical
lattices is discussed based on direct simulations of the time-evolution of the
many-body state in the framework of the Bose-Hubbard model. We focus on
small-amplitude modulations of the lattice potential as implemented in several
recent experiment and study different observables in the region of the first
resonance in the Mott-insulator phase. In addition to the energy transfer we
investigate the quasimomentum structure of the system which is accessible via
the matter-wave interference pattern after a prompt release. We identify
characteristic correlations between the excitation frequency and the
quasimomentum distribution and study their structure in the presence of a
superlattice potential.
\\ ( http://arxiv.org/abs/0706.4260 , 384kb)
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arXiv:0706.4149
Date: Thu, 28 Jun 2007 06:04:14 GMT (221kb)

Title: Integrating cavity quantum electrodynamics and ultracold-atom chips with
on-chip dielectric mirrors and temperature stabilization
Authors: T.P. Purdy, D.M. Stamper-Kurn
Categories: quant-ph
\\
We have fabricated an atom chip device which combines the circuitry for
magnetic trapping of cold atoms with high-finesse optical resonators suitable
for cavity QED in the single-atom strong coupling regime. Fabry-Perot optical
resonators with finesse F > 2 X 10^5 were formed between a micropatterned
on-chip planar mirror with lateral dimension of < 100 um and a curved mirror
suspended above the chip. The strong and rapid thermal coupling between on-chip
electrical and optical elements was utilized to stabilize the cavity mirror
separation with servo bandwidth exceeding 100 kHz during simulated operation of
the atom chip.
\\ ( http://arxiv.org/abs/0706.4149 , 221kb)
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\\
arXiv:0706.4159
Date: Thu, 28 Jun 2007 07:50:25 GMT (45kb)

Title: Multimode analysis of the light emitted from a pulsed optical parametric
oscillator
Authors: Anne E. B. Nielsen and Klaus Molmer
Categories: quant-ph
\\
We present a multimode treatment of the optical parametric oscillator, which
is valid for both pulsed and continuous-wave pump fields. The two-time
correlation functions of the output field are derived, and we apply the theory
to analyze a scheme for heralded production of non-classical field states that
may be subsequently stored in an atomic quantum memory.
\\ ( http://arxiv.org/abs/0706.4159 , 45kb)
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The replacments:

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\\
arXiv:0705.2027
replaced with revised version Fri, 22 Jun 2007 14:18:56 GMT (199kb)

Title: Measuring Electric Fields From Surface Contaminants with Neutral Atoms
Authors: J.M. Obrecht, R.J. Wild, E.A. Cornell
Categories: cond-mat.soft physics.atom-ph
Comments: 7 pages, 6 figures, published in Physical Review A
Journal-ref: Phys. Rev. A 75, 062903 (2007)
DOI: 10.1103/PhysRevA.75.062903
\\ ( http://arxiv.org/abs/0705.2027 , 199kb)
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\\
arXiv:cond-mat/0702178
replaced with revised version Fri, 22 Jun 2007 13:16:34 GMT (250kb)

Title: Excited Thomas-Efimov levels in ultracold gases
Authors: Mark D. Lee, Thorsten Koehler, Paul S. Julienne
Categories: cond-mat.other
Comments: 17 pages, 10 eps figures
\\ ( http://arxiv.org/abs/cond-mat/0702178 , 250kb)
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\\
arXiv:cond-mat/0703443
replaced with revised version Fri, 22 Jun 2007 09:42:00 GMT (149kb)

Title: Spectral properties of a Rydberg atom immersed in a Bose-Einstein
condensate
Authors: Stephan Middelkamp, Igor Lesanovsky, and P. Schmelcher
Categories: cond-mat.other
\\ ( http://arxiv.org/abs/cond-mat/0703443 , 149kb)
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\\
arXiv:physics/0612143
replaced with revised version Fri, 22 Jun 2007 12:26:29 GMT (138kb)

Title: Dynamical interferences to probe short-pulse photoassociation of Rb
atoms and stabilization of Rb_2 dimers
Authors: Jordi Mur-Petit, Eliane Luc-Koenig, Fran\c{c}oise Masnou-Seeuws
Categories: physics.atom-ph cond-mat.other quant-ph
Comments: 4 pages, 5 figures. v2: major changes in introduction, discussion
clarified. v3: minor corrections. v4: matches published version
Journal-ref: Phys. Rev. A 75, 061404(R) (2007)
DOI: 10.1103/PhysRevA.75.061404
\\ ( http://arxiv.org/abs/physics/0612143 , 138kb)
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\\
arXiv:cond-mat/0702649
replaced with revised version Sun, 24 Jun 2007 06:34:32 GMT (995kb)

Title: Quantum dynamics of Raman-coupled Bose-Einstein condensates using
Laguerre-Gaussian beams
Authors: Rina Kanamoto, Ewan M. Wright, Pierre Meystre
Categories: cond-mat.other
Journal-ref: Phys. Rev. A 75, 063623 (2007)
\\ ( http://arxiv.org/abs/cond-mat/0702649 , 995kb)
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\\
arXiv:cond-mat/0702067
replaced with revised version Tue, 26 Jun 2007 18:55:08 GMT (203kb)

Title: Time-dependent quantum many-body theory of identical bosons in a double
well: Early time ballistic interferences of fragmented and number entangled
states
Authors: David J. Masiello, William P. Reinhardt
Categories: cond-mat.other
\\ ( http://arxiv.org/abs/cond-mat/0702067 , 203kb)
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\\
arXiv:cond-mat/0702269
replaced with revised version Thu, 28 Jun 2007 09:34:35 GMT (967kb)

Title: Off-diagonal long-range order, cycle probabilities, and condensate
fraction in the ideal Bose gas
Authors: Maguelonne Chevallier, Werner Krauth
Categories: cond-mat.stat-mech
Comments: 6 pages, extensive rewriting, new section on maximum-length cycles
\\ ( http://arxiv.org/abs/cond-mat/0702269 , 967kb)
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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 Fri Jul 06 2007 - 14:24:35 EST

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