[Matts-arxiv] Matt's arXiv selection: week ending 3 July 2009

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Sat, 05 Sep 2009 19:27:01 +1000

Dear subscribers,

I'm finishing this posting on the bus to San Feliu de Guixols and BEC2009, where
I look forward to seeing many of you! Geoff Lee did the initial compiling for
this week: there are 12 new preprints and 13 replacements:

Date: Fri, 26 Jun 2009 08:44:23 GMT (750kb)

Title: Dark soliton decay due to trap anharmonicity in atomic Bose-Einstein
Authors: N. G. Parker, N. P. Proukakis and C. S. Adams
Categories: cond-mat.quant-gas
Comments: 10 pages, 9 figures
   A number of recent experiments with nearly pure atomic Bose-Einstein
condensates have confirmed the predicted dark soliton oscillations when under
harmonic trapping. However, a dark soliton propagating in an inhomogeneous
condensate has also been predicted to be unstable to the emission of sound
waves. Although harmonic trapping supports an equilibrium between the
co-existing soliton and sound, we show that the ensuing dynamics are sensitive
to trap anharmonicities. Such anharmonicities can break the soliton-sound
equilibrium and lead to the net decay of the soliton on a considerably shorter
timescale than other dissipation mechanisms. Thus, we propose how small
realistic modifications to existing experimental set-ups could enable the
experimental observation of this decay channel.
\\ ( http://arxiv.org/abs/0906.4877 , 750kb)
Date: Fri, 26 Jun 2009 14:16:45 GMT (1519kb)

Title: Quantum Many-Body Dynamics of Dark Solitons in Optical Lattices
Authors: R. V. Mishmash, I. Danshita, Charles W. Clark, and L. D. Carr
Categories: cond-mat.quant-gas cond-mat.mes-hall
Comments: 14 pages, 11 figures
   We present a fully quantum many-body treatment of dark solitons formed by
ultracold bosonic atoms in one-dimensional optical lattices. Using a
single-band Bose-Hubbard Hamiltonian as the governing model, we consider the
quantum dynamics of density and phase engineered dark solitons as well as the
quantum evolution of mean-field dark solitons injected into the quantum model.
The former approach directly models how one may create quantum entangled dark
solitons in experiment. We show that quantum fluctuations cause a finite
soliton lifetime and induce an inelasticity in soliton-soliton collisions.
Comparisons are made to the Bogoliubov theory which predicts depletion into an
anomalous mode that fills in the soliton. Our many-body treatment allows us to
go beyond the Bogoliubov approximation and calculate explicitly the dynamics of
the system's natural orbitals.
\\ ( http://arxiv.org/abs/0906.4949 , 1519kb)
Date: Mon, 29 Jun 2009 00:58:51 GMT (8kb)

Title: Variational principle of counting statistics in master equations
Authors: Jun Ohkubo
Categories: cond-mat.stat-mech
Comments: 4 pages, no figure
   We study counting statistics of number of transitions in a stochastic
process. For mesoscopic systems, a path integral formulation for the counting
statistics has already been derived. We here show that it is also possible to
derive the similar path integral formulation without the assumption of
mesoscopic systems. It has been clarified that the saddle point method for the
path integral is not an approximation, but a valid procedure in the present
derivation. Hence, a variational principle in the counting statistics is
naturally derived. In order to obtain the variational principle, we employ many
independent replicas of the same system. In addition, the Euler-Maclaurin
formula is used in order to connect the discrete and continuous properties of
the system.
\\ ( http://arxiv.org/abs/0906.5187 , 8kb)
Date: Sat, 27 Jun 2009 16:19:30 GMT (928kb)

Title: Ultracold three-body collisions near narrow Feshbach resonances
Authors: Yujun Wang, J. P. D'Incao, and B.D. Esry
Categories: quant-ph
Comments: 5 pages, 3 figures
   We study ultracold three-body collisions of bosons and fermions when the
interatomic interac- tion is tuned near a narrow Feshbach resonance. We show
that the width of the resonance has a substantial impact on the collisional
properties of ultracold gases in the strongly interacting regime. We obtain
numerical and analytical results that allow us to identify universal features
related to the resonance width. For narrow resonances, we have found a
suppression of all inelastic processes in boson systems leading to deeply bound
states and an enhancement for fermion systems.
\\ ( http://arxiv.org/abs/0906.5019 , 928kb)
Date: Tue, 30 Jun 2009 07:33:11 GMT (118kb)

Title: Effect of realistic interatomic interactions and two-body correlation on
   the heat capacity of a trapped BEC
Authors: Anindya Biswas
Categories: cond-mat.quant-gas
Comments: 12 pages, 4 figures
   An approximate many-body theory has been used to calculate the heat capacity
and the condensate fraction of a BEC with effective repulsive interaction. The
effect of interactions has been analyzed and compared with the non-interacting
case. It has been found that the repulsive interaction lowers the critical
temperature from the value found in the non-interacting case. The difference
between the critical temperatures increases with the increase in the total
number of atoms in the trap.
\\ ( http://arxiv.org/abs/0906.5426 , 118kb)
Date: Tue, 30 Jun 2009 16:56:02 GMT (563kb)

Title: Radiofrequency Dressing of Multiple Feshbach Resonances
Authors: A.M. Kaufman (1), R.P. Anderson (1 and 2), Thomas M. Hanna (3), E.
   Tiesinga (4), P.S. Julienne (4), and D.S. Hall (1) ((1) Amherst College, (2)
   Swinburne University of Technology, (3) NIST, (4) JQI, NIST and University of
Categories: cond-mat.quant-gas
Comments: 4 pages, 3 figures, 1 table
   We demonstrate and theoretically analyze the dressing of several proximate
Feshbach resonances in Rb-87 using radiofrequency radiation (rf). We present
accurate measurements and characterizations of the resonances, and the dramatic
changes in scattering properties that can arise through the rf dressing. Our
scattering theory analysis yields quantitative agreement with the experimental
data. We also present a simple interpretation of our results in terms of
rf-coupled bound states interacting with the collision threshold.
\\ ( http://arxiv.org/abs/0906.5587 , 563kb)
Date: Wed, 1 Jul 2009 14:43:32 GMT (356kb)

Title: Anderson localization of a weakly interacting one dimensional Bose gas
Authors: T. Paul, M. Albert, P. Schlagheck, P. Leboeuf, N. Pavloff
Categories: cond-mat.quant-gas
Comments: 20 pages, 13 figures
   We consider the phase coherent transport of a quasi one-dimensional beam of
Bose-Einstein condensed particles through a disordered potential of length L.
Among the possible different types of flow identified in [T. Paul et al., Phys.
Rev. Lett. 98, 210602 (2007)], we focus here on the supersonic stationary
regime where Anderson localization exists. We generalize the diffusion
formalism of Dorokhov-Mello-Pereyra-Kumar (DMPK) to include interaction
effects. It is shown that interactions modify the localization length and also
introduce a new length scale L* for the disordered region, above which most of
the realizations of the random potential lead to time dependent flows. A
Fokker-Planck equation for the probability density of the transmission
coefficient that takes this new effect into account is introduced and solved.
The theoretical predictions are verified numerically for different types of
disordered potentials. Experimental scenarios for observing our predictions are
\\ ( http://arxiv.org/abs/0907.0098 , 356kb)
Date: Wed, 1 Jul 2009 13:05:09 GMT (998kb)

Title: Is an Ultra-Cold Strongly Interacting Fermi Gas a Perfect Fluid?
Authors: J. E. Thomas
Categories: cond-mat.quant-gas
Comments: 8 pages, 5 figures, submitted to conference proceedings, Quark Matter
   Fermi gases with magnetically tunable interactions provide a clean and
controllable laboratory system for modeling interparticle interactions between
fermions in nature. The s-wave scattering length, which is dominant a low
temperature, is made to diverge by tuning near a collisional (Feshbach)
resonance. In this regime, two-component Fermi gases are stable and strongly
interacting, enabling tests of nonperturbative many-body theories in a variety
of disciplines, from high temperature superconductors to neutron matter and
quark-gluon plasmas. We have developed model-independent methods for measuring
the entropy and energy of this model system, providing a benchmark for
calculations of the thermodynamics. Our experiments on the expansion of
rotating strongly interacting Fermi gases in the normal fluid regime reveal
extremely low viscosity hydrodynamics. Combining the thermodynamic and
hydrodynamic measurements enables an estimate of the ratio of the shear
viscosity to the entropy density. A strongly interacting Fermi gas in the
normal fluid regime is found to be a nearly perfect fluid, where the ratio of
the viscosity to the entropy density is close to a universal minimum that has
been conjectured by string theory methods.
\\ ( http://arxiv.org/abs/0907.0140 , 998kb)
Date: Thu, 2 Jul 2009 15:00:37 GMT (399kb)

Title: Universal dephasing of many-body Rabi oscillations of atoms in one
   dimensional traps
Authors: Sebastian D. Huber and Ehud Altman
Categories: cond-mat.quant-gas cond-mat.str-el
Comments: 4 pages, 2 figures
   We study a quantum quench in a system of two coupled one dimensional tubes of
interacting atoms. After the quench the system is out of equilibrium and
oscillates between the tubes with a frequency determined by microscopic
parameters. Despite the high energy at which the system is prepared we find an
emergent long timescale responsible for the dephasing of the oscillations and a
transition at which this timescale diverges. We show that the universal
properties of the dephasing and the transition arise from an infrared
orthogonality catastrophe. Furthermore, we show how this universal behavior is
realized in a realistic model of fermions with attractive interactions.
\\ ( http://arxiv.org/abs/0907.0267 , 399kb)
Date: Thu, 2 Jul 2009 10:47:47 GMT (65kb)

Title: Anderson localization of solitons
Authors: Krzysztof Sacha, Cord A. M\"ueller, Dominique Delande, and Jakub
Categories: cond-mat.quant-gas
Comments: 4 pages, 2 figures
   At very low temperature, a quasi-one-dimensional ensemble of atoms with
attractive interaction forms a bright soliton. When exposed to a sufficiently
weak and smooth external potential, the shape of the soliton is not modified,
but its center-of-mass motion is affected. We show that in the presence of a
spatially correlated disordered potential, the quantum motion of a bright
soliton shows Anderson localization. The localization length can be much larger
than the soliton size and could be observed experimentally.
\\ ( http://arxiv.org/abs/0907.0338 , 65kb)
Date: Thu, 2 Jul 2009 16:24:49 GMT (245kb)

Title: Frustrated quantum antiferromagnetism with ultracold bosons in a
   triangular lattice
Authors: A. Eckardt, P. Hauke, P. Soltan-Panahi, C. Becker, K. Sengstock, and
   M. Lewenstein
Categories: cond-mat.quant-gas cond-mat.other
Comments: 4 pages, 3 figures
   We propose to realize the triangular-lattice Bose-Hubbard model with positive
tunneling matrix elements by using ultracold atoms in an optical lattice
dressed by a fast lattice oscillation. This model resembles geometrically
frustrated antiferromagnetism; it interpolates between a classical rotor model
for weak interaction and a quantum spin-1/2 XY-model in the limit of hard-core
bosons. This allows to experimentally explore gapped spin liquid phases,
recently predicted for the anisotropic spin model [Schmied et al., New J. Phys.
10, 045017 (2008)].
\\ ( http://arxiv.org/abs/0907.0423 , 245kb)

The replacements:

Date: Mon, 12 Jan 2009 01:10:26 GMT (414kb)
Date (revised v2): Mon, 29 Jun 2009 06:51:30 GMT (474kb)

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 quant-ph
Comments: 5 pages, 5 figures, published in Physical Review A
Journal-ref: Phys. Rev. A 79, 063630 (2009)
DOI: 10.1103/PhysRevA.79.063630
   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.
\\ ( http://arxiv.org/abs/0901.1484 , 474kb)
replaced with revised version Fri, 22 May 2009 11:43:02 GMT (393kb)

Title: Unified picture of superfluidity: From Bogoliubov's approximation to
   Popov's hydrodynamic theory
Authors: N. Dupuis
Categories: cond-mat.other
Comments: v2) 4 pages, 4 figures v3) Revised title + minor changes
Journal-ref: Phys. Rev. Lett. 102, 190401 (2009)
DOI: 10.1103/PhysRevLett.102.190401
\\ ( http://arxiv.org/abs/0901.4631 , 393kb)
replaced with revised version Fri, 22 May 2009 07:57:03 GMT (114kb)

Title: Multimode quantum memory based on atomic frequency combs
Authors: Mikael Afzelius, Christoph Simon, Hugues de Riedmatten, and Nicolas
Categories: quant-ph
Comments: Final version: 9 pages, 3 figures
Journal-ref: Phys. Rev. A 79, 052329 (2009)
\\ ( http://arxiv.org/abs/0805.4164 , 114kb)
replaced with revised version Fri, 22 May 2009 10:03:43 GMT (1138kb,D)

Title: Quantum resonances in an atom-optical delta-kicked harmonic oscillator
Authors: T. P. Billam and S. A. Gardiner
Categories: quant-ph
Comments: 10 pages, 6 figures. Manuscript revised and extended
\\ ( http://arxiv.org/abs/0809.4373 , 1138kb)
replaced with revised version Tue, 26 May 2009 09:31:34 GMT (27kb)

Title: Superfluid Pairing in the Three Component Fermi Gas
Authors: S. Y. Chang, V. R. Pandharipande
Categories: physics.atom-ph
Comments: 4
\\ ( http://arxiv.org/abs/physics/0607008 , 27kb)
replaced with revised version Wed, 27 May 2009 18:45:29 GMT (14kb)

Title: Absence of a Direct Superfluid to Mott Insulator Transition in
   Disordered Bose Systems
Authors: L. Pollet, N.V. Prokof'ev, B. V. Svistunov, M. Troyer
Categories: cond-mat.stat-mech cond-mat.other
Comments: 4 pages, 3 figures; replaced with resubmitted version
\\ ( http://arxiv.org/abs/0903.3867 , 14kb)
replaced with revised version Wed, 27 May 2009 21:24:28 GMT (404kb)

Title: The Finite Temperature Pairing Gap of a Unitary Fermi Gas by Quantum
   Monte Carlo
Authors: P. Magierski, G. Wlazlowski, A. Bulgac and J.E. Drut
Categories: cond-mat.stat-mech nucl-th
Comments: 4 pages, 5 figures. New material, substantial changes
\\ ( http://arxiv.org/abs/0801.1504 , 404kb)
replaced with revised version Thu, 28 May 2009 04:58:07 GMT (1527kb,D)

Title: Suppression of collisional decoherence
Authors: Yoav Sagi, Ido Almog and Nir Davidson
Categories: quant-ph
Comments: 4 pages, 5 figures, typos corrected and a few minor changes
\\ ( http://arxiv.org/abs/0905.0286 , 1527kb)

And just for fun:

Date: Fri, 26 Jun 2009 14:25:13 GMT (1095kb)

Title: Mental states follow quantum mechanics during perception and cognition
   of ambiguous figures
Authors: Elio Conte, Andrei Yuri Khrennikov, Orlando Todarello, Antonio
   Federici, Leonardo Mendolicchio, Joseph P. Zbilut
Categories: physics.gen-ph
Journal-ref: Open Systems and Information Dynamics, 16, 1, 85-100, 2009
DOI: 10.1142/S1230161209000074
   Processes undergoing quantum mechanics, exhibit quantum interference effects.
In this case quantum probabilities result to be different from classical
probabilities because they contain an additional main point that in fact is
called the quantum interference term. We use ambiguous figures to analyse if
during perception cognition of human subjects we have violation of the
classical probability field and quantum interference. The experiments,
conducted on a group of 256 subjects, evidence that we have such quantum
effect. Therefore, mental states, during perception cognition of ambiguous
figures, follow quantum mechanics
\\ ( http://arxiv.org/abs/0906.4952 , 1095kb)

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,                  mdavis_at_physics.uq.edu.au
Australia.                           www.physics.uq.edu.au/people/mdavis/
Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org
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Received on Thu Sep 24 2009 - 15:47:36 EST

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