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

Date: Fri, 10 Jul 2009 14:35:14 +1000

Date: Fri, 10 Jul 2009 14:35:14 +1000

Dear subscribers,

I'm still enlisting the help of my colleagues... today we can thank Geoff Lee

again. This mail contains 11 new preprints and 7 replacements.

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arXiv:0905.2897

Date: Mon, 18 May 2009 14:35:04 GMT (869kb)

Title: Single-laser, one beam, tetrahedral magneto-optical trap

Authors: Matthieu Vangeleyn, Paul F. Griffin, Erling Riis, Aidan S. Arnold

Categories: physics.atom-ph

Comments: 8 pages, 6 figures, 2 movies

\\

We have realised a 4-beam pyramidal magneto-optical trap ideally

suited for future microfabrication. Three mirrors split and steer a single

incoming beam into a tripod of reflected beams, allowing trapping in the

four-beam overlap volume. We discuss the influence of mirror angle on cooling

and trapping, finding optimum efficiency in a tetrahedral configuration. We

demonstrate the technique using an ex-vacuo mirror system to illustrate the

previously inaccessible supra-plane pyramid MOT configuration. Unlike standard

pyramidal MOTs both the pyramid apex and its mirror angle are non-critical and

our MOT offers improved molasses free from atomic shadows in the laser beams.

The MOT scheme naturally extends to a 2-beam refractive version with high

optical access. For quantum gas experiments, the mirror system could also be

used for a stable 3D tetrahedral optical lattice.

\\ ( http://arxiv.org/abs/0905.2897 , 869kb)

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arXiv:0905.3634

Date: Fri, 22 May 2009 13:49:31 GMT (362kb)

Title: Black hole radiation in Bose-Einstein condensates

Authors: Jean Macher and Renaud Parentani

Categories: cond-mat.quant-gas

Comments: revTeX 4, 55 pages single-column, 19 figures

\\

We study the phonon fluxes emitted when the condensate velocity crosses the

speed of sound, i.e., in backgrounds which are analogue to that of a black

hole. We focus on elongated one dimensional condensates, and on stationary

flows. Our theoretical analysis and numerical results are based on the

Bogoliubov-de-Gennes equation without any further approximation. The spectral

properties of the fluxes and of the long distance density-density correlations

are obtained, with and without an initial temperature. In realistic conditions,

we show that the condensate temperature dominates the fluxes, and thus hides

the presence of the spontaneous emission (the Hawking effect). We also explain

why the temperature amplifies the long distance correlations which are

intrinsic to this effect. This confirms that the correlations pattern offers a

neat signature of the Hawking effect. Optimal conditions to observe the pattern

are discussed.

\\ ( http://arxiv.org/abs/0905.3634 , 362kb)

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arXiv:0905.3660

Date: Fri, 22 May 2009 10:56:15 GMT (328kb)

Title: Collapse instability of solitons in the nonpolynomial Schr\"{o}dinger

equation with dipole-dipole interactions

Authors: G. Gligoric, A. Maluckov, Lj. Hadzievski, and B. A. Malomed

Categories: cond-mat.quant-gas

Comments: 6 figures

\\

A model of the Bose-Einstein condensate (BEC) of dipolar atoms, confined in a

combination of a cigar-shaped trap and optical lattice acting in the axial

direction, is studied in the framework of the one-dimensional (1D)

nonpolynomial Schr\"{o}dinger equation (NPSE) with additional terms describing

long-range dipole-dipole (DD) interactions. The NPSE makes it possible to

describe the collapse of localized modes, which was experimentally observed in

the self-attractive BEC confined in tight traps, in the framework of the 1D

description. We study the influence of the DD interactions on the dynamics of

bright solitons, especially as concerns their collapse-induced instability.

Both attractive and repulsive contact and DD interactions are considered. The

results are summarized in the form of stability/collapse diagrams in a

respective parametric space. In particular, it is shown that the attractive DD

interactions may prevent the collapse instability in the condensate with

attractive contact interactions.

\\ ( http://arxiv.org/abs/0905.3660 , 328kb)

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arXiv:0905.3541

Date: Thu, 21 May 2009 18:20:05 GMT (152kb)

Title: Dispersive propagation of ultraslow light in an atomic Bose-Einstein

condensate

Authors: Devrim Tarhan, Seckin Sefi, and Ozgur E. Mustecaplioglu

Categories: physics.optics cond-mat.quant-gas quant-ph

Comments: 14 pages, 3 figures

\\

One dimensional propagation of ultraslow optical pulses in an atomic

Bose-Einstein condensate taking into account the dispersion and the spatial

inhomogeneity is investigated. Analytical and semi-analytical solutions of the

dispersive inhomogeneous wave equation modeling the ultraslow pulse propagation

are developed and compared against the standard wave equation solvers based

upon Cranck-Nicholson and pseudo-spectral methods. The role of curvature of the

trapping potential of the condensate on the amount of dispersion of the

ultraslow pulse is pointed out.

\\ ( http://arxiv.org/abs/0905.3541 , 152kb)

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arXiv:0905.3384

Date: Wed, 20 May 2009 20:00:28 GMT (452kb)

Title: Representation of quantum dynamics of interacting systems through

classical trajectories

Authors: Anatoli Polkovnikov

Categories: cond-mat.stat-mech cond-mat.quant-gas hep-th quant-ph

Comments: 82 pages (single column), 17 figures

\\

We formulate representation of quantum dynamics of many-particle interacting

systems through classical trajectories as a perturbative expansion in quantum

fluctuations around the classical limit. We explicitly consider three different

classical limits in the coordinate-momentum representation (corpuscular

classical limit), coherent state representation (wave classical limit), and the

classical limit for spin systems. We describe how one recovers truncated Wigner

approximation (TWA) in the leading order in quantum fluctuations around each of

these limits. Further quantum corrections can be found either in the form of

non-linear response of observables to infinitesimal quantum jumps or

equivalently in terms of stochastic quantum jumps with non-positive weight. We

discuss how one can find both equal and non-equal time correlation functions

within this approach and which correlation functions have casual

representation. Our approach is closely related to phase space methods based on

Weyl quantization, coherent state phase space methods, and Keldysh diagrammatic

technique. We show how both new results and earlier concepts naturally emerge

from combining path-integral approach and the Heisenberg representation. We

illustrate this approach with various examples including sine-Gordon model,

one- and two-dimensional Bose Hubbard model, Dicke model and others.

\\ ( http://arxiv.org/abs/0905.3384 , 452kb)

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arXiv:0905.3894

Date: Sun, 24 May 2009 12:14:26 GMT (399kb)

Title: Anomalous scaling of fermions and order parameter fluctuations at

quantum criticality

Authors: P. Strack, S. Takei, and W. Metzner

Categories: cond-mat.str-el cond-mat.stat-mech

Comments: 8 pages, 9 figures, submitted to Phys. Rev. B

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We analyze the quantum phase transition between a semimetal and a superfluid

in a model of attractively interacting fermions with a linear dispersion. The

quantum critical properties of this model cannot be treated by the Hertz-Millis

approach since integrating out the fermions leads to a singular Landau-Ginzburg

order parameter functional. We therefore derive and solve coupled

renormalization group equations for the fermionic degrees of freedom and the

bosonic order parameter fluctuations. In two spatial dimensions, fermions and

bosons acquire anomalous scaling dimensions at the quantum critical point,

associated with non-Fermi liquid behavior and non-Gaussian order parameter

fluctuations.

\\ ( http://arxiv.org/abs/0905.3894 , 399kb)

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arXiv:0905.4005

Date: Mon, 25 May 2009 19:30:54 GMT (522kb)

Title: Superfluid--Mott Insulator Transition of Light in the Jaynes-Cummings

Lattice

Authors: Jens Koch, Karyn Le Hur

Categories: cond-mat.other

Comments: 13 pages, 5 figures

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Regular arrays of electromagnetic resonators, in turn coupled coherently to

individual quantum two-level systems, exhibit a quantum phase transition of

polaritons from a superfluid phase to a Mott-insulating phase. The critical

behavior of such a Jaynes-Cummings lattice thus resembles the physics of the

Bose-Hubbard model. We explore this analogy by elaborating on the mean-field

theory of the phase transition, and by presenting several useful mappings which

pinpoint both similarities and differences of the two models. We show that a

field-theory approach can be applied to prove the existence of multicritical

curves analogous to the multicritical points of the Bose-Hubbard model, and we

provide analytical expressions for the position of these curves.

\\ ( http://arxiv.org/abs/0905.4005 , 522kb)

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arXiv:0905.3974

Date: Mon, 25 May 2009 09:00:16 GMT (829kb)

Title: Efimov states in atom-molecular collisions

Authors: M.A. Efremov, L. Plimak, B. Berg, M.Yu. Ivanov and W.P. Schleich

Categories: quant-ph

Comments: 4 pages, 2 figures

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We analyse scattering of a heavy atom off a weakly bound molecule comprising

an identical heavy and a light atom in the Born-Oppenheimer approximation. We

focus on the situation where the heavy atoms are bosons, which was realized in

several experiments. The elastic and inelastic cross sections for the

atom-molecular scattering exhibit a series of resonances corresponding to

three-body Efimov states. Resonances in elastic collisions are accessible

experimentally through thermalization rates, and thus constitute an alternative

way of observing Efimov states.

\\ ( http://arxiv.org/abs/0905.3974 , 829kb)

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arXiv:0905.4238

Date: Tue, 26 May 2009 16:50:06 GMT (65kb)

Title: Random Number Generators: A Survival Guide for Large Scale Simulations

Authors: Stephan Mertens

Categories: cond-mat.stat-mech physics.comp-ph

Comments: Lecture at the summer school "Modern Computation Science", 16-28

August 2009, Oldenburg (Germany), see http://www.mcs.uni-oldenburg.de/

\\

Monte Carlo simulations are an important tool in statistical physics, complex

systems science, and many other fields. An increasing number of these

simulations is run on parallel systems ranging from multicore desktop computers

to supercomputers with thousands of CPUs. This raises the issue of generating

large amounts of random numbers in a parallel application. In this lecture we

will learn just enough of the theory of pseudo random number generation to make

wise decisions on how to choose and how to use random number generators when it

comes to large scale, parallel simulations.

\\ ( http://arxiv.org/abs/0905.4238 , 65kb)

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arXiv:0905.4254

Date: Tue, 26 May 2009 17:41:29 GMT (10kb)

Title: Fluctuation-dissipation theorem and harmonic oscillators

Authors: Vincenzo Branchina, Marco Di Liberto, Ivano Lodato

Categories: cond-mat.stat-mech

Comments: 11 pages, no figures

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The question of the "physical meaning" and "origin" of the Bose-Einstein (BE)

factor in the fluctuation-dissipation theorem (FDT) is often raised and this

term is sometimes interpreted as originating from a real harmonic oscillator

composition of the physical system. Such an interpretation, however, is not

really founded. Inspired by the famous work of Caldeira and Leggett, we have

been able to show that, whenever linear response theory is applicable, which is

the main hypothesis under which the FDT is established, any generic bosonic

and/or fermionic system at temperature $T$ can be mapped onto a fictitious

system of harmonic oscillators so that the suscettivity and the mean square of

the fluctuating observable of the real system coincide with the corresponding

quantities of the fictitious one. We claim that it is in this sense, and only

in this sense, that the BE factor can be interpreted in terms of harmonic

oscillators, no other physical meaning can be superimposed to it. At the best

of our knowledge, this is the first time that such a mapping is explicitly

worked out.

\\ ( http://arxiv.org/abs/0905.4254 , 10kb)

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arXiv:0905.4649

Date: Thu, 28 May 2009 13:38:09 GMT (325kb)

Title: Frequency matching in light storage spectroscopy of atomic Raman

transitions

Authors: Leon Karpa, Gor Nikoghosyan, Frank Vewinger, Michael Fleischhauer,

Martin Weitz

Categories: physics.atom-ph physics.optics

Comments: 9 pages, 4 figures. submitted for publication

\\

We investigate the storage of light in an atomic sample with a lambda-type

coupling scheme driven by optical fields at variable two-photon detuning. In

the presence of electromagnetically induced transparency (EIT), light is stored

and retrieved from the sample by dynamically varying the group velocity. It is

found that for any two-photon detuning of the input light pulse within the EIT

transparency window, the carrier frequency of the retrieved light pulse matches

the two-photon resonance frequency with the atomic ground state transition and

the control field. This effect which is not based on spectral filtering is

investigated both theoretically and experimentally. It can be used for

high-speed precision measurements of the two-photon resonance as employed e.g.

in optical magnetometry.

\\ ( http://arxiv.org/abs/0905.4649 , 325kb)

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The replacements:

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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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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 Fri Jul 10 2009 - 16:01:01 EST

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