Matt's arXiv selection, Monday 4th September 2006.

From: Matthew Davis <>
Date: Mon, 4 Sep 2006 10:38:59 +1000 (EST)

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

Hi all,

Back on track this week with the abstracts.

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The abstracts:

Paper: cond-mat/0608611
Date: Mon, 28 Aug 2006 20:00:32 GMT (47kb)

Title: Excited state spectra at the superfluid-insulator transition out of
   paired condensates
Authors: Stephen Powell and Subir Sachdev
Comments: 4 pages, 1 figure
Subj-class: Strongly Correlated Electrons; Superconductivity
   We describe gapped single-particle and collective excitations across a
superfluid to insulator quantum phase transition of particles (bosons or
fermions) in a periodic potential, with an even number of particles per unit
cell. We demonstrate that the dynamics is controlled by a quantum impurity
problem of a localized particle interacting with the bulk critical modes.
Critical exponents are determined by a renormalization group analysis. We
discuss applications to spin oscillations of ultracold atoms in optical
lattices, and to the electronic phases in the cuprate and related compounds.
\\ ( , 47kb)
Paper: cond-mat/0608624
Date: Tue, 29 Aug 2006 07:06:26 GMT (197kb)

Title: Fermionization and fractional statistics in the strongly interacting
   one-dimensional Bose gas
Authors: M.T. Batchelor and X.-W. Guan
Comments: 7 pages, 4 figures
Subj-class: Statistical Mechanics; Strongly Correlated Electrons
   We discuss recent results on the relation between the strongly interacting
one-dimensional Bose gas and a gas of ideal particles obeying nonmutual
generalized exclusion statistics (GES). The thermodynamic properties considered
include the statistical profiles, the specific heat and local pair
correlations. In the strong coupling limit $\gamma \to \infty$, the
Tonks-Girardeau gas, the equivalence is with Fermi statistics. The deviation
from Fermi statistics during boson fermionization for finite but large
interaction strength $\gamma$ is described by the relation $\alpha \approx 1 -
2/\gamma$, where $\alpha$ is a measure of the GES. This gives a quantitative
description of the fermionization process. In this sense the recent
experimental measurement of local pair correlations in a 1D Bose gas of
$^{87}$Rb atoms also provides a measure of the deviation of the GES parameter
$\alpha$ away from the pure Fermi statistics value $\alpha=1$. Other
thermodynamic properties, such as the distribution profiles and the specific
heat, are also sensitive to the statistics. They also thus provide a way of
exploring fractional statistics in the strongly interacting 1D Bose gas.
\\ ( , 197kb)
Paper: cond-mat/0608634
Date: Tue, 29 Aug 2006 13:52:37 GMT (403kb)

Title: Quantum dynamics in splitting a harmonically trapped Bose-Einstein
   condensate by an optical lattice: Truncated Wigner approximation
Authors: L. Isella, J. Ruostekoski
Comments: 17 pages
Subj-class: Other
   We study the splitting of a harmonically trapped atomic Bose-Einstein
condensate when we continuously turn up an optical lattice (or a double-well)
potential. As the lattice height is increased, quantum fluctuations of atoms
are enhanced. The resulting nonequilibrium dynamics of the fragmentation
process of the condensate, the loss of the phase coherence of atoms along the
lattice, and the reduced atom number fluctuations in individual lattice sites
are stochastically studied within the truncated Wigner approximation. We
perform a detailed study of the effects of temperature and lattice height on
atom dynamics, and investigate the validity of the classical Gross-Pitaevskii
equation in optical lattices. We find the atom number squeezing to saturate in
deep lattices due to nonadiabaticity in turning up of the lattice potential
that is challenging to avoid in experiments when the occupation number of the
lattice sites is large, making it difficult to produce strongly number squeezed
(or the Mott insulator) states with large filling factors. We also investigate
some general numerical properties of the truncated Wigner approximation.
\\ ( , 403kb)
Paper: cond-mat/0608639
Date: Tue, 29 Aug 2006 16:00:28 GMT (695kb)

Title: Correlations in Ultracold Trapped Few-Boson Systems: Transition from
   Condensation to Fermionization
Authors: Sascha Z\"ollner, Hans-Dieter Meyer and Peter Schmelcher
Comments: 22 pages, 7 figures
Subj-class: Other
   We study the correlation properties of the ground states of few ultracold
bosons, trapped in double wells of varying barrier height in one dimension.
Extending previous results on the signature of the transition from a
Bose-condensed state via fragmentation to the hard-core limit, we provide a
deeper understanding of that transition by relating it to the loss of coherence
in the one-body density matrix and to the emerging long-range tail in the
momentum spectrum. These are accounted for in detail by discussing the natural
orbitals and their occupations. Our discussion is complemented by an analysis
of the two-body correlation function.
\\ ( , 695kb)
Paper: cond-mat/0606117
replaced with revised version Tue, 29 Aug 2006 06:32:06 GMT (13kb)

Title: Fermions at unitarity and Haldane Exclusion Statistics
Authors: R.K. Bhaduri, M.V.N. Murthy and M.K. Srivastava
Comments: 4 pages, 1 postscript figure
Subj-class: Other
\\ ( , 13kb)
Paper: physics/0604008
replaced with revised version Tue, 29 Aug 2006 12:44:00 GMT (359kb)

Title: Anomalous translational velocity of vortex ring with finite-amplitude
   Kelvin waves
Authors: C.F. Barenghi, R. Hanninen, M. Tsubota
Comments: 6 pages, 5 figures, v2: minor changes
Subj-class: Fluid Dynamics; Soft Condensed Matter
\\ ( , 359kb)
Paper: quant-ph/0608222
Date: Mon, 28 Aug 2006 23:22:00 GMT (775kb)

Title: Quantum dynamics of bosons in a double-well potential: Josephson
   oscillations, self-trapping and ultralong tunneling times
Authors: A. N. Salgueiro, A. F. R. de Toledo Piza, G. B. Lemos, R. Drumond, M.
   C. Nemes and M. Weidemueller
   The dynamics of the population imbalance of bosons in a double-well potential
is investigated from the point of view of many-body quantum mechanics in the
framework of the two-mode model. For small initial population imbalances,
coherent superpositions of almost equally spaced energy eigenstates lead to
Josephson oscillations. The suppression of tunneling at population imbalance
beyond a critical value is related to a high concentration of initial state
population in the region of the energy spectrum with quasi-degenerate doublets
resulting in imbalance oscillations with a very small amplitude. For
unaccessible long times, however, the system recovers the regime of Josephson
\\ ( , 775kb)
Paper: quant-ph/0608228
Date: Tue, 29 Aug 2006 08:25:45 GMT (492kb)

Title: Radio-frequency dressed state potentials for neutral atoms
Authors: S. Hofferberth, I. Lesanovsky, B. Fischer, J. Verdu, J. Schmiedmayer
   Potentials for atoms can be created by external fields acting on properties
like magnetic moment, charge, polarizability, or by oscillating fields which
couple internal states. The most prominent realization of the latter is the
optical dipole potential formed by coupling ground and electronically excited
states of an atom with light. Here we present an experimental investigation of
the remarkable properties of potentials derived from radio-frequency (RF)
coupling between electronic ground states. The coupling is magnetic and the
vector character allows to design state dependent potential landscapes. On atom
chips this enables robust coherent atom manipulation on much smaller spatial
scales than possible with static fields alone. We find no additional heating or
collisional loss up to densities approaching $10^{15}$ atoms / cm$^3$ compared
to static magnetic traps. We demonstrate the creation of Bose-Einstein
condensates in RF potentials and investigate the difference in the interference
between two independently created and two coherently split condensates in
identical traps. All together this makes RF dressing a powerful new tool for
micro manipulation of atomic and molecular systems.
\\ ( , 492kb)
Paper: quant-ph/0604158
replaced with revised version Mon, 28 Aug 2006 21:13:18 GMT (852kb)

Title: Semiclassical approach to Bose-Einstein condensates in a triple well
Authors: S. Mossmann, C. Jung
Comments: 15 pages, 15 figures
\\ ( , 852kb)
Paper: cond-mat/0608651
Date: Wed, 30 Aug 2006 00:15:11 GMT (83kb)

Title: Polarized Fermi condensates with unequal masses: Tuning the tricritical
Authors: M. M. Parish, F. M. Marchetti, A. Lamacraft, B. D. Simons
Comments: 5 pages, 5 figures
Subj-class: Other
   We consider a two-component atomic Fermi gas within a mean-field,
single-channel model, where both the mass and population of each component are
unequal. We show that the tricritical point at zero temperature evolves
smoothly from the BEC- to BCS-side of the resonance as a function of mass ratio
r. We find that the interior gap state proposed by Liu and Wilczek is always
unstable to phase separation, while the breached pair state with one Fermi
surface for the excess fermions exhibits differences in its DoSs and pair
correlation functions depending on which side of the resonance it lies.
Finally, we show that, when r > 3.95, the finite temperature phase diagram of
trapped gases at unitarity becomes topologically distinct from the equal mass
\\ ( , 83kb)
Paper: cond-mat/0608656
Date: Wed, 30 Aug 2006 03:39:41 GMT (304kb)

Title: Dynamical vortex phases in a Bose-Einstein condensate driven by a
   rotating optical lattice
Authors: Kenichi Kasamatsu, Makoto Tsubota
Comments: 4 pages, 3 figures
Subj-class: Other
   We present simulation results of the vortex dynamics in a trapped
Bose-Einstein condensate in the presence of a rotating optical lattice.
Changing the potential amplitude and the relative rotation frequency between
the condensate and the optical lattice, we find a rich variety of dynamical
phases of vortices. The onset of these different phases is described by the
force balance of a driving force, a pinning force and vortex-vortex
interactions. In particular, when the optical lattice rotates faster than the
condensate, an incommensurate effect leads to a vortex liquid phase supported
by the competition between the driving force and the dissipation.
\\ ( , 304kb)
Paper: cond-mat/0608662
Date: Wed, 30 Aug 2006 19:54:04 GMT (50kb)

Title: Theory of Superfluids with Population Imbalance: Finite Temperature and
   BCS-BEC Crossover Effects
Authors: Qijin Chen, Yan He, Chih-Chun Chien and K. Levin
Comments: 15 pages, 5 figures
Subj-class: Strongly Correlated Electrons; Superconductivity
   In this paper we present a very general theoretical framework for addressing
fermionic superfluids over the entire range of BCS to Bose Einstein
condensation (BEC) crossover in the presence of population imbalance or spin
polarization. Our emphasis is on providing a theory which reduces to the
standard zero temperature mean field theories in the literature, but
necessarily includes pairing fluctuation effects at non-zero temperature within
a consistent framework. Physically, these effects are associated with the
presence of pre-formed pairs (or a fermionic pseudogap) in the normal phase,
and pair excitations of the condensate, in the superfluid phase. We show how
this finite $T$ theory of fermionic pair condensates bears many similarities to
the condensation of point bosons. In the process we examine three different
types of condensate: the usual breached pair or Sarma phase and both the one
and two plane wave Larkin- Ovchinnikov, Fulde-Ferrell (LOFF) states. The last
of these has been discussed in the literature albeit only within a
Landau-Ginzburg formalism, generally valid near $T_c$. Here we show how to
arrive at the two plane wave LOFF state in the ground state as well as at
general temperature $T$.
\\ ( , 50kb)
Paper: cond-mat/0608673
Date: Wed, 30 Aug 2006 14:32:57 GMT (336kb)

Title: Spin-quadrupole ordering of spin-3/2 ultracold fermionic atoms in
   optical lattices studied with one-band Hubbard model
Authors: Hong-Hao Tu, Guang-Ming Zhang, Lu Yu
Comments: 11 pages, Revtex, 4 figures
Subj-class: Strongly Correlated Electrons
   Based on a generalized one-band Hubbard model, we study magnetic properties
of Mott insulating states for ultracold spin-3/2 fermionic atoms in optical
lattices. When the s-wave scattering lengths for the total spin $S=2,0$ satisfy
conditions $a_{2}>a_{0}>0$, we apply a functional integral approach to the
half-filled case, where the spin-quadrupole fluctuations dominate. On a 2D
square lattice, the saddle point solution yields a staggered spin-quadrupole
ordering at zero temperature. Both spin and spin-quadrupole static structure
factors are calculated, displaying highly anisotropic spin antiferromagnetic
fluctuations and antiferro-quadrupole long-range order, respectively. When the
Gaussian fluctuations around the saddle point are taken into account, a linear
dispersion of the spin-quadrupole density waves is derived. The corresponding
velocity and stiffness are evaluated and compared with the spin density waves
present in the half-filled spin-1/2 Hubbard model. Finally, in the strong
coupling limit of the model Hamiltonian, we derive the effective hyperfine spin
exchange interactions for the Mott insulating phases in the quarter-filled and
half-filled cases, respectively.
\\ ( , 336kb)
Paper: cond-mat/0608689
Date: Wed, 30 Aug 2006 19:52:14 GMT (59kb)

Title: BEC-BCS crossover of a trapped Fermi gas beyond the local density
Authors: R. Jauregui, R. Paredes, and G. Toledo Sanchez
Comments: 10 pages, 3 figures, 1 table
Subj-class: Other
   We perform a Variational Quantum Monte Carlo simulation of an interacting
  Fermi gas confined in a three dimensional harmonic potential. This gas is
considered as the precursor system from which a molecular bosonic gas is
formed. Based in the results of two-body calculations for trapped atoms, we
propose a family of variational many-body wave functions that takes into
account the qualitative different nature of the BCS and BEC regimes as a
function of the scattering length. Energies, densities and correlations
functions are calculated and compared with previous results for homogeneous
gases. Universality tests at the unitarity limit are also performed.
\\ ( , 59kb)
Paper: quant-ph/0608234
Date: Wed, 30 Aug 2006 00:48:49 GMT (604kb)

Title: Controlled polarization rotation of an optical field in
   multi-Zeeman-sublevel atoms
Authors: Shujing Li, Bo Wang, Xudong Yang, Yanxu Han, Hai Wang, Min Xiao, K.C.
Comments: 28pages, 12figures
   We investigate, both theoretically and experimentally, the phenomenon of
polarization rotation of a weak, linearly-polarized optical (probe) field in an
atomic system with multiple three-level electromagnetically induced
transparency (EIT) sub-systems. The polarization rotation angle can be
controlled by a circularly-polarized coupling beam, which breaks the symmetry
in number of EIT subsystems seen by the left- and right-circularly-polarized
components of the weak probe beam. A large polarization rotation angle (up to
45 degrees) has been achieved with a coupling beam power of only 15 mW.
Detailed theoretical analyses including different transition probabilities in
different transitions and Doppler-broadening are presented and the results are
in good agreements with the experimentally measured results.
\\ ( , 604kb)
Paper: quant-ph/0608242
Date: Wed, 30 Aug 2006 14:49:08 GMT (456kb)

Title: Creation of macroscopic superposition states from arrays of
   Bose-Einstein condensates
Authors: J.A. Dunningham, K. Burnett, R. Roth, and W.D. Phillips
Comments: 7 pages, 5 figures
DOI: 10.1088/1367-2630/8/5/000
   We consider how macroscopic quantum superpositions may be created from arrays
of Bose-Einstein condensates. We study a system of three condensates in Fock
states, all with the same number of atoms and show that this has the form of a
highly entangled superposition of different quasi-momenta. We then show how, by
partially releasing these condensates and detecting an interference pattern
where they overlap, it is possible to create a macroscopic superposition of
different relative phases for the remaining portions of the condensates. We
discuss methods for confirming these superpositions.
\\ ( , 456kb)
Paper: quant-ph/0605252
replaced with revised version Tue, 29 Aug 2006 22:38:09 GMT (621kb)

Title: Photoassociation adiabatic passage of ultracold Rb atoms to form
   ultracold Rb_2 molecules
Authors: Evgeny A. Shapiro, Moshe Shapiro, Avi Pe'er, and Jun Ye
Comments: RevTex, 23 pages, 9 figures
\\ ( , 621kb)
Paper: cond-mat/0608690
Date: Wed, 30 Aug 2006 23:10:05 GMT (90kb)

Title: Hidden symmetry and quantum phases in spin-3/2 cold atomic systems
Authors: Congjun Wu
Subj-class: Strongly Correlated Electrons
   Optical traps and lattices provide a new opportunity to study strongly
correlated high spin systems with cold atoms. In this article, we review the
recent progress on the hidden symmetry properties in the simplest high spin
fermionic systems with hyperfine spin $F=3/2$, which may be realized with atoms
of $^{132}$Cs, $^9$Be, $^{135}$Ba, $^{137}$Ba, and $^{201}$Hg. A {\it generic}
SO(5) or isomorphically, $Sp(4)$) symmetry is proved in such systems with the
s-wave scattering interactions in optical traps, or with the on-site Hubbard
interactions in optical lattices. Various important features from this high
symmetry are studied in the Fermi liquid theory, the mean field phase diagram,
and the sign problem in quantum Monte-Carlo simulations. In the s-wave quintet
Cooper pairing phase, the half-quantum vortex exhibits the global analogue of
the Alice string and non-Abelian Cheshire charge properties in gauge theories.
The existence of the quartetting phase, a four-fermion counterpart of the
Cooper pairing phase, and its competition with other orders are studied in one
dimensional spin-3/2 systems. We also show that counter-intuitively quantum
fluctuations in spin-3/2 magnetic systems are even stronger than those in
spin-1/2 systems.
\\ ( , 90kb)
Paper: cond-mat/0608710
Date: Thu, 31 Aug 2006 09:33:30 GMT (194kb)

Title: A moving magnetic mirror to slow down a bunch of atoms
Authors: Ga\"{e}l Reinaudi (LKB - Lhomond), Zhaoying Wang (LKB - Lhomond),
   Antoine Couvert (LKB - Lhomond), Thierry Lahaye (LKB - Lhomond), David
   Gu\'{e}ry-Odelin (LKB - Lhomond)
Proxy: ccsd ccsd-00090483
Subj-class: Other
   A fast packet of cold atoms is coupled into a magnetic guide and subsequently
slowed down by reflection on a magnetic potential barrier ('mirror') moving
along the guide. A detailed characterization of the resulting decelerated
packet is performed. We show also how this technique can be used to generate a
continuous and intense flux of slow, magnetically guided atoms.
\\ ( , 194kb)
Paper: cond-mat/0608721
Date: Thu, 31 Aug 2006 14:58:30 GMT (135kb)

Title: Repulsively bound atom pairs: Overview, Simulations and Links
Authors: A. J. Daley, A. Kantian, H. P. Buechler, P. Zoller, K. Winkler, G.
   Thalhammer, F. Lang, R. Grimm, J. Hecker Denschlag
Comments: 7 pages, 3 figures, Proceedings of ICAP-2006 (Innsbruck)
Subj-class: Other
   We review the basic physics of repulsively bound atom pairs in an optical
lattice, which were recently observed in the laboratory, including the theory
and the experimental implementation. We also briefly discuss related many-body
numerical simulations, in which time-dependent Density Matrix Renormalisation
Group (DMRG) methods are used to model the many-body physics of a collection of
interacting pairs, and give a comparison of the single-particle quasimomentum
distribution measured in the experiment and results from these simulations. We
then give a short discussion of how these repulsively bound pairs relate to
bound states in some other physical systems.
\\ ( , 135kb)
Paper: cond-mat/0608732
Date: Thu, 31 Aug 2006 16:56:04 GMT (614kb)

Title: Quantum Spin Dynamics of Spin-1 Bose Gas
Authors: Roberto B. Diener and Tin-Lun Ho
Comments: 4 pages, 2 figures
Subj-class: Other
   We show that the quantum evolution of a spin-1 Bose gas with nearly all
bosons initially in the $F_z = 0$ state has a "quantum carpet" {\em spin-time}
structure with self-similar properties. The system continuously evolves into
"multi-peaked" Schr\"odinger cat like states, returning occasionally to
coherent structures, which leads to large number fluctuations (as seen in
recent experiments). The self similar behavior allows one to reveal the quantum
evolution as a set of peaks in the number probability distribution of a spin
component at times {\em much shorter} than the quantum revival time. We also
show that these features survive small number fluctuations among spin
components up to a few percent.
\\ ( , 614kb)
Paper: cond-mat/0606015
replaced with revised version Thu, 31 Aug 2006 08:05:24 GMT (360kb)

Title: Experimental study of the transport of coherent interacting matter-waves
   in a 1D random potential induced by laser speckle
Authors: David Cl\'{e}ment (LCFIO), Andr\`{e}s F. Var\`{o}n (LCFIO), Jocelyn A.
   Retter (LCFIO), Laurent Sanchez-Palencia (LCFIO), Alain Aspect (LCFIO),
   Philippe Bouyer (LCFIO)
Proxy: ccsd ccsd-00077779
Subj-class: Other
Journal-ref: New Journal of Physics 8 (2006) 165
DOI: 10.1088/1367-2630/8/8/165
\\ ( , 360kb)
Paper: cond-mat/0607045
replaced with revised version Thu, 31 Aug 2006 12:14:36 GMT (66kb)

Title: Bogoliubov theory of Feshbach molecules in the BEC-BCS crossover
Authors: M. W. J. Romans and H. T. C. Stoof
Comments: 13 pages of RevTex and 12 Figures. Submitted for publication in
   Physical review A
Subj-class: Statistical Mechanics; Superconductivity
\\ ( , 66kb)
Paper: cond-mat/0608455
replaced with revised version Wed, 30 Aug 2006 20:33:29 GMT (824kb)

Title: Deformation of a Trapped Fermi Gas with Unequal Spin Populations
Authors: G. B. Partridge, Wenhui Li, Y. A. Liao, R. G. Hulet, M. Haque & H. T.
   C. Stoof
Subj-class: Other; Superconductivity
\\ ( , 824kb)
Paper: quant-ph/0608247
Date: Thu, 31 Aug 2006 06:36:46 GMT (355kb)

Title: Quantum many-body simulations using Gaussian phase-space representations
Authors: P. D. Drummond, P. Deuar, J. F. Corney
Comments: Short Review (10 pages)
   Phase-space representations are of increasing importance as a viable and
successful means to study exponentially complex quantum many-body systems from
first principles. This review traces the background of these methods, starting
from the early work of Wigner, Glauber and Sudarshan. We focus on modern
phase-space approaches using non-classical phase-space representations. These
lead to the Gaussian representation, which unifies bosonic and fermionic
phase-space. Examples treated include quantum solitons in optical fibers,
colliding Bose-Einstein condensates, and strongly correlated fermions on
\\ ( , 355kb)
Paper: quant-ph/0511232
replaced with revised version Thu, 31 Aug 2006 11:37:48 GMT (122kb)

Title: Analysis of a single-atom dipole trap
Authors: Markus Weber, Juergen Volz, Karen Saucke, Christian Kurtsiefer, and
   Harald Weinfurter
Comments: Version 2; formula in equ. 3 corrected
Journal-ref: Phys. Rev. A 73, 043406 (2006)
\\ ( , 122kb)

Till next week,

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
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Received on Mon Sep 04 2006 - 10:38:59 EST

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