Matt's arXiv selection: week ending 27 February 2009

From: Matthew Davis <>
Date: Tue, 19 May 2009 08:44:04 +1000

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

Thanks for this week's abstracts goes to Geoff Lee. There are 13 new preprints
and 7 replacements:

Date: Fri, 20 Feb 2009 19:45:00 GMT (149kb)

Title: Stimulated Raman scattering in an optical parametric oscillator based on
   periodically poled MgO-doped stoichiometric LiTaO3
Authors: T-H. My (LAC), O. Robin (LAC), O. Mhibik (LAC), C. Drag (LAC), and F.
   Bretenaker (LAC)
Categories: physics.optics physics.ins-det
Comments: 6 figures
   The evolution versus pump power of the spectrum of a singly resonant optical
parametric oscillator based on an MgO-doped periodically poled stoichiometric
lithium tantalate crystal is observed. The onset of cascade Raman lasing due to
stimulated Raman scattering in the nonlinear crystal is analyzed. Spurious
frequency doubling and sum-frequency generation phenomena are observed and
understood. A strong reduction of the intracavity Raman scattering is obtained
by a careful adjustment of the cavity losses.
\\ ( , 149kb)
Date: Fri, 20 Feb 2009 23:25:06 GMT (91kb)

Title: The Mass of a Spin Vortex in a Bose-Einstein Condensate
Authors: Ari M. Turner
Categories: cond-mat.other cond-mat.supr-con
Comments: 5 pages, 3 figures
   In contrast to charge vortices in a superfluid, spin vortices in a
ferromagnetic condensate move inertially (if the condensate has zero
magnetization along an axis). The mass of spin vortices depends on the
spin-dependent interactions, and can be measured as a part of experiments on
how spin vortices orbit one another. For Rb87 in a 1 micron thick trap m_v is
about 10^-21 kg.
\\ ( , 91kb)
Date: Sat, 21 Feb 2009 05:49:35 GMT (241kb)

Title: Diffusion of Inhomogeneous Vortex Tangle and Decay of Superfluid
Authors: Sergey K. Nemirovskii
Categories: cond-mat.other
Comments: 7 pages, 6 figures
   The theory describing the evolution of inhomogeneous vortex tangle at zero
temperature is developed on the bases of kinetics of merging and splitting
vortex loops. Vortex loops composing the vortex tangle can move as a whole with
some drift velocity depending on their structure and their length. The flux of
length, energy, momentum etc. executed by the moving vortex loops takes a
place. Situation here is exactly the same as in usual classical kinetic theory
with the difference that the "carriers" of various physical quantities are not
the point particles, but extended objects (vortex loops), which possess an
infinite number of degrees of freedom with very involved dynamics. We offer to
fulfill investigation basing on supposition that vortex loops have a Brownian
structure with the only degree of freedom, namely, lengths of loops $l$. This
conception allows us to study dynamics of the vortex tangle on the basis of the
kinetic equation for the distribution function $n(l,t)$ of the density of a
loop in the space of their lengths. Imposing the coordinate dependence on the
distribution function $n(l,\mathbf{% r},t)$ and modifying the "kinetic"
equation with regard to inhomogeneous situation, we are able to investigate
various problem on the transport processes in superfluid turbulence. In this
paper we derive relation for the flux of the vortex line density
$\mathcal{L}(x,t)$. The correspoding evolution of quantity $\mathcal{L}(x,t)$
obeys the diffusion type equation as it can be expected from dimensional
analysis. The according diffusion coefficient is evaluated from calculation of
the (size dependent) free path of the vortex loops. We use this equation to
describe the decay of the vortex tangle at very low temperature. We compare
that solution with recent experiments on decay of the superfluid turbulence.
\\ ( , 241kb)
Date: Mon, 23 Feb 2009 04:59:30 GMT (31kb)

Title: Reduced fidelity in topological quantum phase transitions
Authors: Erik Eriksson and Henrik Johannesson
Categories: cond-mat.str-el cond-mat.stat-mech
Comments: 4 pages, 2 figures
   We study the reduced fidelity between local states of lattice systems
exhibiting topological order. By exploiting mappings to spin models with
classical order, we are able to analytically extract the scaling behavior of
the reduced fidelity at the corresponding quantum phase transitions out of the
topologically ordered phases. Our results suggest that the reduced fidelity,
albeit being a local measure, generically serves as a faithful marker of a
topological quantum phase transition.
\\ ( , 31kb)
Date: Mon, 23 Feb 2009 17:48:47 GMT (32kb)

Title: Josephson oscillations between exciton condensates in electrostatic
Authors: Massimo Rontani, L. J. Sham
Categories: cond-mat.mes-hall
Comments: RevTeX 4.0. 4 pages, 2 figures
   Technological advances allow for tunable lateral confinement of cold dipolar
excitons in coupled quantum wells. We consider theoretically the Josephson
effect between exciton condensates in two traps separated by a weak link. The
flow of the exciton supercurrent is driven by the dipole energy difference
between the traps. The Josephson oscillations may be observed after ensemble
average of the time correlation of photons separately emitted from the two
traps. The fringe visibility is controlled by the trap coupling and is robust
against quantum and thermal fluctuations.
\\ ( , 32kb)
Date: Mon, 23 Feb 2009 17:59:32 GMT (160kb)

Title: Faraday patterns in dipolar Bose-Einstein condensates
Authors: R. Nath and L. Santos
Categories: cond-mat.other
Comments: 4 pages, 10 figures
   Faraday patterns can be induced in Bose-Einstein condensates by a periodic
modulation of the system nonlinearity. We show that these patterns are
remarkably different in dipolar gases with a roton-maxon excitation spectrum.
Whereas for non-dipolar gases the pattern size decreases monotonously with the
driving frequency, patterns in dipolar gases present, even for shallow roton
minima, a highly non trivial frequency dependence characterized by abrupt
pattern size transitions, which are especially pronounced when the dipolar
interaction is modulated. Faraday patterns constitute hence an optimal tool for
revealing the onset of the roton minimum, a major key feature of dipolar gases.
\\ ( , 160kb)
Date: Mon, 23 Feb 2009 19:58:19 GMT (42kb,D)

Title: Causality in Condensates: Grey Solitons as Remnants of BEC Formation
Authors: Wojciech H. Zurek
Categories: cond-mat.stat-mech
Comments: Phys. Rev. Lett., in press
   Symmetry breaking during phase transitions can lead to the formation of
topological defects (such as vortex lines in superfluids). However, the usually
studied BEC's have the shape of a cigar, a geometry that impedes vortex
formation, survival, and detection. I show that, in elongated traps, one can
expect the formation of "grey solitons" (long-lived, non-topological "phase
defects") as a result of the same mechanism. Their number will rise
approximately in proportion to the transition rate. This steep rise is due to
the increasing size of the region of the BEC cigar where the phase of the
condensate wavefunction is chosen locally (rather than passed on from the
already formed BEC).
\\ ( , 42kb)
Date: Tue, 24 Feb 2009 11:17:08 GMT (34kb)

Title: Multiple condensed phases in attractively interacting Bose systems
Authors: M. M\"annel, K. Morawetz, P. Lipavsk\'y
Categories: cond-mat.stat-mech
   We investigate a Bose gas with finite-range interaction using a scheme to
eliminate unphysical repeated collisions in the T-matrix approximation. In this
way the corrected T-matrix becomes suitable to calculate properties below the
critical temperature. For attractive interaction, the Evans-Rashid transition
occurs from the quasi-ideal Bose gas to the BCS-like phase with a gaped
dispersion. The gap decreases with increasing density and vanishes at a
critical density where the single-particle dispersion becomes linear for small
momenta indicating Bose-Einstein condensation.
\\ ( , 34kb)
Date: Tue, 24 Feb 2009 12:26:57 GMT (444kb)

Title: A new view on superfluidity
Authors: V. A. Golovko
Categories: cond-mat.stat-mech quant-ph
Comments: Full version of a paper published earlier in Physica A, 45 pages, 2
   This paper represents the full version of a paper published earlier in
Physica A [246 (1997), 275]. The present paper includes argumentation, proofs
and details omitted in the shortened version. The papers are a further
development of the approach in quantum statistical mechanics proposed by the
author. The hierarchy of equations for reduced density matrices obtained
previously is extended to the case corresponding to the Bose-Einstein
condensation. The relevant state of the system with a condensate can be
superfluid as well as nonsuperfluid. Special attention is given to the
thermodynamics of superfluid systems. According to the results of the papers
superfluidity is the state of a fluid whose symmetry is spontaneously broken
because of a stationary flow. The state corresponds to thermodynamic
equilibrium while the magnitude of the flow depends upon the temperature and is
determined by thermodynamic considerations. The equations obtained are solved
in two simple cases. The physical origin of superfluidity, peculiarities of the
phenomenon in closed volumes and the critical velocity are discussed as well.
\\ ( , 444kb)
Date: Tue, 24 Feb 2009 17:56:11 GMT (2007kb)

Title: Small Numbers of Vortices in Anisotropic Traps
Authors: S. McEndoo and Th. Busch
Categories: cond-mat.other
Comments: 7 pages, 7 figures
   We investigate the appearance of vortices and vortex lattices in
two-dimensional, anisotropic and rotating Bose-Einstein condensates. Once the
anisotropy reaches a critical value, the positions of the vortex cores in the
ground state are no longer given by an Abrikosov lattice geometry, but by a
linear arrangement. Using a variational approach, we determine the critical
stirring frequency for a single vortex as well as the equilibrium positions of
a small number of vortices.
\\ ( , 2007kb)
Date: Thu, 26 Feb 2009 20:51:55 GMT (402kb)

Title: FFLO vs Bose-Fermi mixture in polarized 1D Fermi gas on a Feshbach
   resonance: a 3-body study
Authors: Stefan K. Baur, John Shumway, Erich J. Mueller
Categories: cond-mat.supr-con
Comments: 4 pages, 3 figures
   We study the three-fermion problem within a 1D model of a Feshbach resonance
in order to gain insight into how the FFLO-like state at small negative
scattering lengths evolves into a Bose-Fermi mixture at small positive
scattering lengths. The FFLO state possesses an oscillating superfluid
correlation function, while in a Bose-Fermi mixture correlations are monotonic.
We find that this behavior is is already present at the 3-body level. We
present an exact study of the 3-body problem, and compare the results to
scalable quantum Monte Carlo calculations.
\\ ( , 402kb)
Date: Thu, 26 Feb 2009 18:10:24 GMT (1493kb)

Title: Binding between two-component bosons in one dimension
Authors: Emmerich Tempfli, Sascha Z\"ollner, Peter Schmelcher
Categories: cond-mat.other
Comments: 9 pages, 10 figures
   We investigate the ground state of one-dimensional few-atom Bose-Bose
mixtures under harmonic confinement throughout the crossover from weak to
strong inter-species attraction. The calculations are based on the numerically
exact multi-configurational time-dependent Hartree method. For repulsive
components we detail the condition for the formation of a molecular
Tonks-Girardeau gas in the regime of intermediate inter-species interactions,
and the formation of a molecular condensate for stronger coupling. Beyond a
critical inter-species attraction, the system collapses to an overall bound
state. Different pathways emerge for different particle numbers and
intra-species interactions. In particular, for mixtures with one attractive
component, this species can be viewed as an effective potential dimple in the
trap center for the other, repulsive component.
\\ ( , 1493kb)
Date: Thu, 26 Feb 2009 07:27:50 GMT (276kb)

Title: Universal scaling in a strongly interacting Rydberg gas
Authors: Robert L\"ow, Hendrik Weimer, Ulrich Raitzsch, Rolf Heidemann, Vera
   Bendkowsky, Bj\"orn Butscher, Hans Peter B\"uchler, and Tilman Pfau
Categories: quant-ph
Comments: 5 pages, 3 figures
   We study a gas of ultracold atoms resonantly driven into a strongly
interacting Rydberg state. The long distance behavior of the spatially frozen
effective pseudospin system is determined by a set of dimensionless parameters,
and we find that the experimental data exhibits algebraic scaling laws for the
excitation dynamics and the saturation of Rydberg excitation. Mean field
calculations as well as numerical simulations provide an excellent agreement
with the experimental finding, and are evidence for universality in a strongly
interacting frozen Rydberg gas.
\\ ( , 276kb)

The replacements:

replaced with revised version Fri, 20 Feb 2009 16:50:40 GMT (198kb,D)

Title: Quantum Simulation of the Hubbard Model: The Attractive Route
Authors: A. F. Ho, M. A. Cazalilla, T. Giamarchi
Categories: cond-mat.str-el
Comments: 11 pages, 5 figs. New version as accepted in PRA. We have clarified
   the models we are discussing in various places, and expanded on the critical
   number estimate to include both K40 and Li6 in section V. Also added
\\ ( , 198kb)
replaced with revised version Thu, 19 Feb 2009 10:06:12 GMT (903kb)

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 cond-mat.other
\\ ( , 903kb)
replaced with revised version Thu, 19 Feb 2009 16:26:38 GMT (205kb,D)

Title: Probing Interactions between Ultracold Fermions
Authors: G. K. Campbell, M. M. Boyd, J. W. Thomsen, M. J. Martin, S. Blatt, M.
   D. Swallows, T. L. Nicholson, T. Fortier, C. W. Oates, S. A. Diddams, N. D.
   Lemke, P. Naidon, P. Julienne, Jun Ye, A. D. Ludlow
Categories: physics.atom-ph cond-mat.other
Comments: accepted to Science
\\ ( , 205kb)
replaced with revised version Sat, 21 Feb 2009 15:54:35 GMT (2738kb)

Title: Solitons with Cubic and Quintic Nonlinearities Modulated in Space and
Authors: A.T. Avelar, D. Bazeia, W.B. Cardoso
Categories: quant-ph cond-mat.soft hep-th
Comments: 4 pages, 6 figures; version to appear in PRE, RC
\\ ( , 2738kb)
replaced with revised version Mon, 23 Feb 2009 01:19:50 GMT (711kb)

Title: Ramsey interferometry with an atom laser
Authors: D. D\"oring, J. E. Debs, N. P. Robins, C. Figl, P. A. Altin, and J. D.
Categories: physics.atom-ph
Comments: submitted version, 4 pages, 3 figures
\\ ( , 711kb)
replaced with revised version Tue, 24 Feb 2009 06:16:46 GMT (16kb)

Title: Defect production due to quenching through a multicritical point
Authors: Uma Divakaran, Victor Mukherjee, Amit Dutta and Diptiman Sen
Categories: cond-mat.stat-mech
Comments: 4 pages, 2 figures, updated references and added one figure
Journal-ref: J. Stat. Mech. (2009) P02007
\\ ( , 16kb)
replaced with revised version Mon, 23 Feb 2009 22:59:35 GMT (241kb)

Title: Polarization-based Light-Atom Quantum Interface with an All-optical Trap
Authors: Marcin Kubasik, Marco Koschorreck, Mario Napolitano, Sebasti\'an R. de
   Echaniz, Herbert Crepaz, J\"urgen Eschner, Eugene S. Polzik, Morgan W.
Categories: quant-ph
Comments: 8 pages, 4 figures
\\ ( , 241kb)

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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Received on Tue May 19 2009 - 11:49:23 EST

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