Matt's arXiv selection: week ending 16 January 2009

From: Matthew Davis <>
Date: Thu, 12 Mar 2009 07:33:13 +1000

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

This week there were 18 new preprints and 13 replacements:

Date: Fri, 9 Jan 2009 03:38:31 GMT (673kb)

Title: Continuous vortex pumping into a spinor condensate with magnetic fields
Authors: Z. F. Xu, P. Zhang, C. Raman, and L. You
Categories: cond-mat.other
Comments: 9 pages, 6 figures
Journal-ref: Phys. Rev. A 78, 043606(2008)
DOI: 10.1103/PhysRevA.78.043606
   We study the mechanisms and the limits of pumping vorticity into a spinor
condensate through manipulations of magnetic (B-) fields. We discover a
fundamental connection between the geometrical properties of the magnetic
fields and the quantized circulation of magnetically trapped atoms, a result
which generalizes several recent experimental and theoretical studies. The
optimal procedures are devised that are capable of continuously increasing or
decreasing a condensate's vorticity by repeating certain two step B-field
manipulation protocols. We carry out detailed numerical simulations that
support the claim that our protocols are highly efficient, stable, and robust
against small imperfections of all types. Our protocols can be implemented
experimentally within current technologies.
\\ ( , 673kb)
Date: Fri, 9 Jan 2009 11:37:17 GMT (151kb)

Title: Ground-state properties of hard-core anyons in one-dimensional optical
Authors: Yajiang Hao, Yunbo Zhang, Shu Chen
Categories: cond-mat.str-el cond-mat.stat-mech
Comments: 5 pages, 4 figures
   We investigate the ground-state properties of anyons confined in
one-dimensional optical lattices with a weak harmonic trap using the exact
numerical method based on Jordan-Wigner transformation. It is shown that in the
Bose limit ($\chi =1$) and Fermi limit ($\chi=0$) the momentum distributions
are symmetric but in between they are asymmetric. It turns out that the origin
of asymmetry comes from the fractional statistics that anyons obey. The
occupation distribution and the modulus of natural orbitals show crossover
behaviours from the Bose limit to the Fermi limit.
\\ ( , 151kb)
Date: Fri, 9 Jan 2009 17:29:33 GMT (82kb)

Title: Quasi-Universal Dipolar Scattering in Cold and Ultracold Gases
Authors: J. L. Bohn, M. Cavagnero, and C. Ticknor
Categories: physics.atom-ph
Comments: 19 pages, 5 figures
   We investigate the scattering cross section of aligned dipolar molecules in
low-temperature gases. Over a wide range of collision energies relevant to
contemporary experiments, the cross section declines in inverse proportion to
the collision speed, and is given nearly exactly by a simple semiclassical
formula. At yet lower energies, the cross section becomes independent of
energy, and is reproduced within the Born approximation to within corrections
due to the s-wave scattering length. While these behaviors are universal for
all polar molecules, nevertheless interesting deviations from universality are
expected to occur in the intermediate energy range.
\\ ( , 82kb)
Date: Fri, 9 Jan 2009 19:31:05 GMT (778kb)

Title: Coherent collapse of a dipolar Bose-Einstein condensate for different
   trap geometries
Authors: J Metz, T Lahaye, B Fr\"ohlich, A Griesmaier, T Pfau, H Saito, Y
   Kawaguchi, and M Ueda
Categories: physics.atom-ph
   We experimentally investigate the collapse dynamics of dipolar Bose-Einstein
condensates of Chromium atoms in different harmonic trap geometries, from
prolate to oblate. The evolutions of the condensates in the unstable regime are
compared to three-dimensional simulations of the Gross-Pitaevskii equation
including three-body losses. In order to probe the phase coherence of the
collapsed condensate, we interfere several copies and observe high fringe
\\ ( , 778kb)
Date: Sat, 10 Jan 2009 08:39:17 GMT (1687kb)

Title: Matter Wave Interference Pattern in the collision of bright solitons
   (Bose Einstein condensates) in a time dependent trap
Authors: V. Ramesh Kumar, R. Radha, and Prasanta K. Panigrahi
Categories: cond-mat.other
   We show that it is possible to observe matter wave interference patterns in
the collision of bright solitons (Bose Einstein condensates) without free
ballistic expansion for suitable choices of scattering length and time
dependent trap.
\\ ( , 1687kb)
Date: Sun, 11 Jan 2009 06:31:15 GMT (337kb)

Title: Unconventional Bose-Einstein Condensations Beyond the "No-node" Theorem
Authors: Congjun Wu
Categories: cond-mat.supr-con cond-mat.str-el
   Feynman's "no-node" theorem states that the conventional many-body
ground-state wavefunctions of bosons in the coordinate representation is
positive-definite. This implies that time-reversal symmetry cannot be
spontaneously broken. In this article, we review our progress in studying a
class of new states of unconventional Bose-Einstein condensations beyond this
paradigm. These states can either be the long-lived metal-stable states of
ultra-cold bosons in high orbital bands in optical lattices as a result of the
"orbital-Hund's rule" interaction, or the ground states of spinful bosons with
spin-orbit coupling linearly dependent on momentum. In both cases, Feynman's
argument does not apply. The resultant many-body wavefunctions are
complex-valued and thus break time-reversal symmetry spontaneously. Exotic
phenomena in these states include the Bose-Einstein condensation at non-zero
momentum, the ordering of orbital angular momentum moments, the half-quantum
vortex, and the spin texture of skyrmions.
\\ ( , 337kb)
Date: Mon, 12 Jan 2009 05:18:14 GMT (97kb)

Title: A binary mixture of spinor atomic Bose-Einstein condensates
Authors: Z. F. Xu, Yunbo Zhang, and L. You
Categories: cond-mat.other
Comments: 5 pages, 4 figures
   We study the ground state and classify its phase diagram for a mixture of two
spin-1 condensates in the absence of external magnetic (B-) field according to
atomic parameters for intra- and inter-species spin exchange coupling and
singlet pairing interaction. Ignoring the inter-species singlet pairing
interaction, the ground state phases are found analytically. Numerical approach
of simulated annealing is adopted when the singlet pairing interaction is
present. Our results on the phase diagram and the boundaries between phases
allow for easy identifications of quantum phase transitions, that can be
induced through the tuning of optical traps and atom numbers. They provide the
first insight and guidance for several ongoing experiments on mixtures of
spinor condensates.
\\ ( , 97kb)
Date: Sat, 10 Jan 2009 16:33:49 GMT (2462kb,D)

Title: Quantum and Classical Dynamics of a BEC in a Large-Period Optical
Authors: J. H. Huckans, I. B. Spielman, B. Laburthe Tolra, W. D. Phillips, and
   J. V. Porto
Categories: quant-ph
Comments: 7 pages, 6 figures
   We experimentally investigate diffraction of a Rb-87 Bose-Einstein condensate
from a 1D optical lattice. We use a range of lattice periods and timescales,
including those beyond the Raman-Nath limit. We compare the results to quantum
mechanical and classical simulations, with quantitative and qualitative
agreement, respectively. The classical simulation predicts that the envelope of
the time-evolving diffraction pattern is shaped by caustics: singularities in
the phase space density of classical trajectories. This behavior becomes
increasingly clear as the lattice period grows.
\\ ( , 2462kb)
Date: Mon, 12 Jan 2009 00:26:22 GMT (174kb,D)

Title: Multi-channel modelling of the formation of vibrationally cold polar KRb
Authors: Svetlana Kotochigova, Eite Tiesinga, and Paul S. Julienne
Categories: quant-ph
Comments: 14 pages, 9 figures
   We describe the theoretical advances that influenced the experimental
creation of vibrationally and translationally cold polar $^{40}$K$^{87}$Rb
molecules \cite{nphys08,science08}. Cold molecules were created from
very-weakly bound molecules formed by magnetic field sweeps near a Feshbach
resonance in collisions of ultra-cold $^{40}$K and $^{87}$Rb atoms. Our
analysis include the multi-channel bound-state calculations of the hyperfine
and Zeeman mixed X$^1\Sigma^+$ and a$^3\Sigma^+$ vibrational levels. We find
excellent agreement with the hyperfine structure observed in experimental data.
In addition, we studied the spin-orbit mixing in the intermediate state of the
Raman transition. This allowed us to investigate its effect on the
vibrationally-averaged transition dipole moment to the lowest ro-vibrational
level of the X$^1\Sigma^+$ state. Finally, we obtained an estimate of the
polarizability of the initial and final ro-vibrational states of the Raman
transition near frequencies relevant for optical trapping of the molecules.
\\ ( , 174kb)
Date: Mon, 12 Jan 2009 02:25:01 GMT (332kb)

Title: Coherent Transport of Atomic Quantum States in a Scalable Shift Register
Authors: A. Lengwenus, J. Kruse, G. Birkl
Categories: quant-ph
   The coherent storage and transport of atomic quantum systems in versatile
potential geometries is one of the key elements in many applications of quantum
information processing as well as in Bose-Einstein condensate physics. In this
work we present the controlled coherent transport of 2D-arrays of small samples
of neutral atoms in a register-type trapping geometry produced by
two-dimensional arrays of microlenses. We show the scalability of the transport
process up to macroscopic distances by demonstrating the repeated hand over of
atoms from trap to trap. We investigate the processes of moving and reloading
in detail. Finally we demonstrate the coherence during the transport.
\\ ( , 332kb)
Date: Tue, 30 Dec 2008 18:51:13 GMT (163kb)
Date (revised v2): Sat, 10 Jan 2009 00:39:04 GMT (121kb)

Title: New Kinds of Quantum Statistics
Authors: Frank Wilczek
Categories: hep-th cond-mat.str-el quant-ph
Comments: Talk at Seminaire Poincare (Bourbaphy), Paris, December 2007. To be
   published in the Proceedings. 6 pages, 4 figures. v2: Minor typos corrected,
   figures redrawn
Report-no: MIT-CTP 3997
   I review the quantum kinematics of identical particles, which suggests new
possibilities, beyond bosons and fermions, in 2+1 dimensions; and how simple
flux-charge constructions embody the new possibilities, leading to both abelian
and nonabelian anyons. I briefly allude to experimental realizations, and also
advertise a spinor construction of nonabelian statistics, that has a 3+1
dimensional extension.
\\ ( , 121kb)
Date: Mon, 12 Jan 2009 01:10:26 GMT (414kb)

Title: Pulsed pumping of a Bose-Einstein condensate
Authors: D. D\"oring, G. R. Dennis, N. P. Robins, M. Jeppesen, C. Figl, J. J.
   Hope, and J. D. Close
Categories: physics.atom-ph
Comments: 4 pages, 4 figures
   In this work, we examine a system for coherent transfer of atoms into a
Bose-Einstein condensate. We utilize two spatially separate Bose-Einstein
condensates in different hyperfine ground states held in the same DC magnetic
trap. By means of a pulsed transfer of atoms, we are able to show a clear
resonance in the timing of the transfer, both in temperature and number, from
which we draw conclusions about the underlying physical process. The results
are discussed in the context of the recently demonstrated pumped atom laser.
\\ ( , 414kb)
Date: Mon, 12 Jan 2009 09:27:48 GMT (858kb)

Title: Coherence of Spin-Polarized Fermions Interacting with a Clock Laser in a
   Stark-Shift-Free Optical Lattice
Authors: Masao Takamoto, Hidetoshi Katori
Categories: physics.atom-ph
Comments: 10 pages, 4 figures
Journal-ref: J. Phys. Soc. Jpn. 78, 013301 (2009)
DOI: 10.1143/JPSJ.78.013301
   We investigated the coherence of spin-polarized ^{87}Sr atoms trapped in a
light-shift-free one-dimensional optical lattice during their interaction with
a clock laser on the ^1S_0-^3P_0 transition. Collapses and revivals appeared
for more than 50 Rabi cycles, attributed to the thermal distribution of
discrete vibrational states in the lattice potential. The population
oscillation in the clock states lasted more than 1s, demonstrating high
immunity from decoherence. This long atomic coherence suggests the feasibility
of Pauli blocking of collisions in optical clock excitation.
\\ ( , 858kb)
Date: Wed, 14 Jan 2009 10:40:42 GMT (148kb)

Title: Hall Effect in spinor condensates
Authors: Mathieu Taillefumier, Eskil D. Kuhl, Arne Brattass and Walter
Categories: cond-mat.mes-hall
   We consider a neutral spinor condensate moving in a periodic magnetic field.
The spatially dependent magnetic field induces an effective spin dependent
Lorentz force which in turn gives rise to a spin dependent Hall effect.
Simulations of the Gross-Pitaevskii equation quantify the Hall effect. We
discuss possible experimental realizations.
\\ ( , 148kb)
Date: Wed, 14 Jan 2009 14:50:41 GMT (194kb)

Title: Charge and spin transport in strongly correlated 1D quantum systems
   driven far from equilibrium
Authors: Giuliano Benenti, Giulio Casati, Tomaz Prosen, Davide Rossini, Marko
Categories: cond-mat.str-el
Comments: 16 pages, 17 figures
   We study the charge conductivity in one-dimensional prototype models of
interacting particles, such as the Hubbard and the t-V spinless fermion model,
when coupled to some external baths injecting and extracting particles at the
boundaries. We show that, if these systems are driven far from equilibrium, a
negative differential conductivity regime can arise. The above electronic
models can be mapped into Heisenberg-like spin ladders coupled to two magnetic
baths, so that charge transport mechanisms are explained in terms of quantum
spin transport. The negative differential conductivity is due to oppositely
polarized ferromagnetic domains which arise at the edges of the chain, and
therefore inhibit spin transport: we propose a qualitative understanding of the
phenomenon by analyzing the localization of one-magnon excitations created at
the borders of a ferromagnetic region. We also show that negative differential
conductivity is stable against breaking of integrability. Numerical simulations
of non-equilibrium time evolution have been performed by employing a
Monte-Carlo wave function approach and a matrix product operator formalism.
\\ ( , 194kb)
Date: Thu, 15 Jan 2009 07:59:04 GMT (480kb)

Title: A Mott Insulator of Ultracold Alkaline-Earth-Like Atoms
Authors: Takeshi Fukuhara, Seiji Sugawa, Masahito Sugimoto, Shintaro Taie,
   Yoshiro Takahashi
Categories: cond-mat.other
Comments: 4 pages, 3 figures
   The transition from a superfluid to a Mott insulator (MI) phase has been
observed in a Bose-Einstein condensate (BEC) of ytterbium (Yb) atoms in an
optical lattice. An all-optically produced BEC of 174Yb atoms was loaded into
three-dimensional optical lattices produced by a 532 nm laser beam. The
interference pattern was measured after releasing the quantum gas from the
trapping potential. As increasing the optical lattice depth, we observed the
disappearance of the interference patterns, which is a signature of entering
the MI regime. This result is an important step into studies by using a
combination of the MI state and the ultranarrow optical transition of ultracold
alkaline-earth-like atoms.
\\ ( , 480kb)
Date: Thu, 15 Jan 2009 13:55:11 GMT (460kb,D)

Title: Matrix Product States: Symmetries and Two-Body Hamiltonians
Authors: M. Sanz, M. M. Wolf, D. Perez-Garcia and J. I. Cirac
Categories: cond-mat.str-el
Comments: PDFLatex, 12 pages and 6 figures
   We characterize the conditions under which a translationally invariant matrix
product state (MPS) is invariant under local transformations. This allows us to
relate the symmetry group of a given state to the symmetry group of a simple
tensor. We exploit this result in order to prove and extend a version of the
Lieb-Schultz-Mattis theorem, one of the basic results in many-body physics, in
the context of MPS. We illustrate the results with an exhaustive search of
SU(2)--invariant two-body Hamiltonians which have such MPS as exact ground
states or excitations.
\\ ( , 460kb)
Date: Thu, 15 Jan 2009 16:09:05 GMT (1411kb)

Title: Photonic spectrum of bichromatic optical lattices
Authors: Stefan Rist, Patrizia Vignolo, Giovanna Morigi
Categories: quant-ph
Comments: 10 pages, 10 figures
   We study the photonic spectrum of a one-dimensional optical lattice
possessing a double primitive cell, when the atoms are well localized at the
lattice minima. While a one-dimensional lattice with a simple Wigner-Seitz cell
always possesses a photonic bandgap at the atomic resonance, in this
configuration the photonic transmission spectrum may exhibit none, double or
multiple photonic bandgaps depending on the ratio between the interparticle
distance $\varrho$ inside the cell and the cell size $a$. The transmission
spectra of a weak incident probe are evaluated when the atoms are trapped in
free space and inside an optical resonator for realistic experimental
\\ ( , 1411kb)

The replacements:

replaced with revised version Thu, 8 Jan 2009 23:13:39 GMT (911kb)

Title: Detection of continuous variable entanglement without coherent local
Authors: A. J. Ferris, M. K. Olsen, E. G. Cavalcanti, and M. J. Davis
Categories: quant-ph
Comments: 7 Pages, 4 Figures
Journal-ref: Phys. Rev. A 75, 060104(R) (2008)
DOI: 10.1103/PhysRevA.78.060104
\\ ( , 911kb)
replaced with revised version Mon, 12 Jan 2009 12:34:59 GMT (69kb)

Title: LOFF and breached pairing with cold atoms
Authors: Amruta Mishra and Hiranmaya Mishra
Categories: cond-mat.supr-con hep-ph nucl-th
Comments: 14 pages including 10 figures, Some figures redrawn with more data
   points, more references added, few sentences added in discussions, version to
   appear in Eur. Phys. Journal D
\\ ( , 69kb)
replaced with revised version Mon, 12 Jan 2009 17:51:41 GMT (881kb)

Title: Meta-nematic, smectic and crystalline phases of dipolar fermions in an
   optical lattice
Authors: J. Quintanilla, S. T. Carr, J. J. Betouras
Categories: cond-mat.other cond-mat.str-el
Comments: revised version with additional discussions and references
\\ ( , 881kb)
replaced with revised version Mon, 12 Jan 2009 15:45:28 GMT (185kb)

Title: Trapped Phase-Segregated Bose-Fermi Mixtures and their Collective
Authors: Bert Van Schaeybroeck and Achilleas Lazarides
Categories: cond-mat.stat-mech cond-mat.other
Comments: 6 pages, 4 figures, accepted for publication in Phys. Rev. A
\\ ( , 185kb)
replaced with revised version Mon, 12 Jan 2009 15:54:40 GMT (18kb)

Title: Hidden order in bosonic gases confined in one dimensional optical
Authors: L. Amico, G. Mazzarella, S. Pasini, and F.S. Cataliotti
Categories: cond-mat.other cond-mat.stat-mech hep-th quant-ph
Comments: 5 pages; 1 eps figure. Revised version
\\ ( , 18kb)
replaced with revised version Sat, 10 Jan 2009 22:54:42 GMT (276kb)

Title: Quantum switching at a mean-field instability of a Bose-Einstein
   condensate in an optical lattice
Authors: V. S. Shchesnovich and V. V. Konotop
Categories: cond-mat.other cond-mat.mes-hall nlin.CD quant-ph
Comments: 4 pages, 3 figures (2 in color)
\\ ( , 276kb)
replaced with revised version Sun, 11 Jan 2009 00:06:58 GMT (496kb)

Title: Classical and quantum dynamics of pulsating instability in a
   Bose-Einstein condensate in an optical lattice
Authors: Uttam Shrestha
Categories: cond-mat.other
Comments: This paper has been replaced
\\ ( , 496kb)
replaced with revised version Mon, 12 Jan 2009 10:30:45 GMT (33kb)

Title: Photon-assisted tunneling in optical lattices: Ballistic transport of
   interacting boson pairs
Authors: Christoph Weiss (LKB - Lhomond), Heinz-Peter Breuer
Categories: cond-mat.other
Comments: 7 pages, 3 figures, minor changes
\\ ( , 33kb)
replaced with revised version Mon, 12 Jan 2009 13:41:10 GMT (1850kb)

Title: Multimode Memories in Atomic Ensembles
Authors: J. Nunn, K. Reim, K. C. Lee, V. O. Lorenz, B. Sussman, I. A. Walmsley,
   D. Jaksch
Categories: quant-ph
Comments: Published version. Many thanks are due to Christoph Simon for his
   help and suggestions. (This acknowledgement is missing from the final draft:
Journal-ref: Phys. Rev. Lett. 101, 260502 (2008)
DOI: 10.1103/PhysRevLett.101.260502
\\ ( , 1850kb)
replaced with revised version Wed, 14 Jan 2009 16:42:56 GMT (149kb)

Title: Optical Lenses for Atomic Beams
Authors: Ole Steuernagel
Categories: quant-ph physics.optics
Comments: 10 figures
\\ ( , 149kb)
replaced with revised version Thu, 15 Jan 2009 01:37:19 GMT (339kb)

Title: Symmetry Breaking and Self-trapping of a Dipolar Bose-Einstein
   Condensate in a Double-well Potential
Authors: Bo Xiong, Jiangbin Gong, Han Pu, Weizhu Bao, and Baowen Li
Categories: cond-mat.other
Comments: 9 pages, 5 figures, corrected a missing factor of two in one
   equation, to be published in Physical Review A
\\ ( , 339kb)
replaced with revised version Thu, 15 Jan 2009 14:58:32 GMT (171kb)

Title: Stochastic optimization of a cold atom experiment using a genetic
Authors: Wolfgang Rohringer, Robert Buecker, Stephanie Manz, Thomas Betz,
   Christian Koller, Martin Goebel, Aurelien Perrin, Joerg Schmiedmayer,
   Thorsten Schumm
Categories: physics.atom-ph
Comments: 4 pages, 3 figures
\\ ( , 171kb)
replaced with revised version Thu, 15 Jan 2009 15:26:11 GMT (280kb)

Title: Ultracold molecules from ultracold atoms: a case study with the KRb
Authors: Paul S. Julienne
Categories: physics.atom-ph physics.chem-ph
Comments: Paper for the Discussions of the Faraday Society, Number 142: Cold
   and Ultracold Molecules, April 15-17, 2009, Durham University, UK;Version 2
   is accepted for publication with some typographical corrections and minor
   text and figure revisions for clarification
\\ ( , 280kb)

Till next time,

Dr M. J. Davis,                      Associate Professor in Physics
School of Mathematics and Physics,   ph  : +61 7 334 69824
The University of Queensland,        fax : +61 7 336 51242
Brisbane, QLD 4072,        
Matt's arXiv selection: weekly summary of cold-atom papers from
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