From: Matthew Davis <mdavis_at_physics.uq.edu.au>

Date: Sat, 05 Sep 2009 19:27:01 +1000

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:

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arXiv:0906.4877

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

Title: Dark soliton decay due to trap anharmonicity in atomic Bose-Einstein

condensates

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)

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arXiv:0906.4949

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)

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arXiv:0906.5187

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)

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arXiv:0906.5019

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)

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arXiv:0906.5426

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)

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arXiv:0906.5587

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

Maryland)

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)

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arXiv:0907.0098

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

discussed.

\\ ( http://arxiv.org/abs/0907.0098 , 356kb)

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arXiv:0907.0140

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

09

\\

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)

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arXiv:0907.0267

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)

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arXiv:0907.0338

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

Zakrzewski

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)

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arXiv:0907.0423

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)

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The replacements:

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arXiv:0901.1484

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)

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arXiv:0901.4631

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)

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arXiv:0805.4164

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

Gisin

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)

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arXiv:0809.4373

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)

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arXiv:physics/0607008

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)

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arXiv:0903.3867

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)

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arXiv:0801.1504

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)

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arXiv:0905.0286

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)

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And just for fun:

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arXiv:0906.4952

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)

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Till next time,

Matt.

-- ========================================================================= 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 http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland ========================================================================= _______________________________________________ Matts-arxiv mailing list Matts-arxiv_at_lists.sps.uq.edu.auReceived on Thu Sep 24 2009 - 15:47:36 EST

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