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

Date: Mon, 25 May 2009 08:41:26 +1000

Date: Mon, 25 May 2009 08:41:26 +1000

The following message was sent to the matts_arxiv list by Matthew Davis <mdavis_at_physics.uq.edu.au>

Dear subscribers,

We have Jacopo Sabbatini to thank for this week's message. There are 18 new

preprints and 6 replacements.

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arXiv:0904.0454

Date: Fri, 3 Apr 2009 14:28:39 GMT (3kb)

Title: Doublon-Holon binding in a half-filled band

Authors: Philip Phillips

Categories: cond-mat.str-el

Comments: This is a 1-page comment on S. Sakai, Y. Motome, and M. Imada, PRL,

vol. 102, 056404 (2009)

\\

The arguments presented in PRL. vol. 102, 056404 (2009) are discussed in the

context of the vast literature on spectral weight transfer in doped Mott

insulators. We show that the conclusions regarding spectral weight transfer in

PRL. vol. 102, 056404 (2009) are, where novel, internally inconsistent and

where correct, have been reached at least 18 years ago.

\\ ( http://arxiv.org/abs/0904.0454 , 3kb)

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arXiv:0904.0480

Date: Thu, 2 Apr 2009 22:17:06 GMT (87kb)

Title: Application of the Feshbach-resonance management to a tightly confined

Bose-Einstein condensate

Authors: Giovanni Filatrella, Boris A. Malomed and Luca Salasnich

Categories: cond-mat.quant-gas cond-mat.other

Comments: Physical Review A, in press

\\

We study suppression of the collapse and stabilization of matter-wave

solitons by means of time-periodic modulation of the effective nonlinearity,

using the nonpolynomial Schroedinger equation (NPSE) for BEC trapped in a tight

cigar-shaped potential. By means of systematic simulations, a stability region

is identified in the plane of the modulation amplitude and frequency. In the

low-frequency regime, solitons feature chaotic evolution, although they remain

robust objects.

\\ ( http://arxiv.org/abs/0904.0480 , 87kb)

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arXiv:0904.0569

Date: Fri, 3 Apr 2009 13:43:42 GMT (33kb)

Title: Multi-particle composites in density-imbalanced quantum fluids

Authors: Evgeni Burovski, Giuliano Orso, and Thierry Jolicoeur

Categories: cond-mat.quant-gas cond-mat.supr-con

Comments: 4+ pages, 1 figure

\\

We consider two-component one-dimensional quantum gases with density

imbalance. While generically such fluids are two-component Luttinger liquids,

we show that if the ratio of the densities is a rational number, p/q, and mass

asymmetry between components is sufficiently strong, one of the two eigenmodes

acquires a gap. The gapped phase corresponds to (algebraic) ordering of

(p+q)-particle composites. In particular, for attractive mixtures, this implies

that the superconducting correlations are destroyed. We illustrate our

predictions by numerical simulations of the fermionic Hubbard model with

hopping asymmetry.

\\ ( http://arxiv.org/abs/0904.0569 , 33kb)

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arXiv:0904.0310

Date: Thu, 2 Apr 2009 05:53:08 GMT (168kb)

Title: All-optical Imprinting of Geometric Phases onto Matter Waves

Authors: Qi Zhang, Jiangbin Gong, and C.H. Oh

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

Comments: 5 pages, 2 figures, to appear in Phys. Rev. A

\\

Traditional optical phase imprinting of matter waves is of a dynamical

nature. In this paper we show that both Abelian and non-Abelian geometric

phases can be optically imprinted onto matter waves, yielding a number of

interesting phenomena such as wavepacket re-directing and wavepacket splitting.

In addition to their fundamental interest, our results open up new

opportunities for robust optical control of matter waves.

\\ ( http://arxiv.org/abs/0904.0310 , 168kb)

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arXiv:0904.0749

Date: Mon, 6 Apr 2009 12:46:56 GMT (23kb)

Title: Bose systems in spatially random or time-varying potentials

Authors: V.I. Yukalov, E.P. Yukalova, and V.S. Bagnato

Categories: cond-mat.dis-nn cond-mat.mes-hall

Comments: latex file, 26 pages, 1 figure

Journal-ref: Laser Phys. 19 (2009) 686-699

\\

Bose systems, subject to the action of external random potentials, are

considered. For describing the system properties, under the action of spatially

random potentials of arbitrary strength, the stochastic mean-field

approximation is employed. When the strength of disorder increases, the

extended Bose-Einstein condensate fragments into spatially disconnected

regions, forming a granular condensate. Increasing the strength of disorder

even more transforms the granular condensate into the normal glass. The

influence of time-dependent external potentials is also discussed. Fast varying

temporal potentials, to some extent, imitate the action of spatially random

potentials. In particular, strong time-alternating potential can induce the

appearance of a nonequilibrium granular condensate.

\\ ( http://arxiv.org/abs/0904.0749 , 23kb)

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arXiv:0904.0905

Date: Mon, 6 Apr 2009 12:25:55 GMT (77kb)

Title: Process chain approach to the Bose-Hubbard model: Ground-state

properties and phase diagram

Authors: Niklas Teichmann, Dennis Hinrichs, Martin Holthaus, Andre Eckardt

Categories: cond-mat.other

Comments: 15 pages, 20 figures

\\

We carry out a perturbative analysis, of high order in the tunneling

parameter, of the ground state of the homogeneous Bose-Hubbard model in the

Mott insulator phase. This is made possible by a diagrammatic process chain

approach, derived from Kato's representation of the many-body perturbation

series, which can be implemented numerically in a straightforward manner. We

compute ground-state energies, atom-atom correlation functions, density-density

correlations, and occupation number fluctuations, for one-, two-, and

three-dimensional lattices with arbitrary integer filling. A phenomenological

scaling behavior is found which renders the data almost independent of the

filling factor. In addition, the process chain approach is employed for

calculating the boundary between the Mott insulator phase and the superfluid

phase with high accuracy. We also consider systems with dimensionalities d>3,

thus monitoring the approach to the mean-field limit. The versatility of the

method suggests further applications to other systems which are less well

understood.

\\ ( http://arxiv.org/abs/0904.0905 , 77kb)

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arXiv:0904.0935

Date: Mon, 6 Apr 2009 14:45:41 GMT (951kb)

Title: Collisions of Ultracold Trapped Cesium Feshbach Molecules

Authors: F. Ferlaino, S. Knoop, M. Berninger, M. Mark, H.-C. Naegerl, and R.

Grimm

Categories: cond-mat.quant-gas cond-mat.other

Comments: To appear in Laser Physics, special issue in memoriam Prof. Vladilen

S. Letokhov

\\

We study collisions in an optically trapped, pure sample of ultracold Cs$_2$

molecules in various internal states. The molecular gas is created by Feshbach

association from a near-degenerate atomic gas, with adjustable temperatures in

the nanokelvin range. We identify several narrow loss resonances, which point

to the coupling to more complex molecular states and may be interpreted as

Feshbach resonances in dimer-dimer interactions. Moreover, in some molecular

states we observe a surprising temperature dependence in collisional loss. This

shows that the situation cannot be understood in terms of the usual simple

threshold behavior for inelastic two-body collisions. We interpret this

observation as further evidence for a more complex molecular structure beyond

the well-understood dimer physics.

\\ ( http://arxiv.org/abs/0904.0935 , 951kb)

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arXiv:0904.0976

Date: Mon, 6 Apr 2009 18:13:20 GMT (89kb)

Title: Dynamical phase transition in correlated fermionic lattice systems

Authors: Martin Eckstein, Marcus Kollar, Philipp Werner

Categories: cond-mat.str-el

Comments: 4 pages, 3 figures

\\

We use non-equilibrium dynamical mean-field theory to demonstrate the

existence of a critical interaction in the real-time dynamics of the Hubbard

model after an interaction quench. The critical point is characterized by fast

thermalization and separates weak-coupling and strong-coupling regimes in which

the relaxation is delayed due to prethermalization on intermediate timescales.

This dynamical phase transition should be observable in experiments on trapped

fermionic atoms.

\\ ( http://arxiv.org/abs/0904.0976 , 89kb)

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arXiv:0810.1720

Date: Thu, 9 Oct 2008 18:59:30 GMT (68kb)

Title: Momentum-space interferometry with trapped ultracold atoms

Authors: A. Ruschhaupt, A. del Campo, J. G. Muga

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

Comments: 8 pages

Journal-ref: Phys. Rev. A 79, 023616 (2009)

\\

Quantum interferometers are generally set so that phase differences between

paths in coordinate space combine constructive or destructively. Indeed, the

interfering paths can also meet in momentum space leading to momentum-space

fringes. We propose and analyze a method to produce interference in momentum

space by phase-imprinting part of a trapped atomic cloud with a detuned laser.

For one-particle wave functions analytical expressions are found for the fringe

width and shift versus the phase imprinted. The effects of unsharpness or

displacement of the phase jump are also studied, as well as many-body effects

to determine the potential applicability of momentum-space interferometry.

\\ ( http://arxiv.org/abs/0810.1720 , 68kb)

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arXiv:0904.0995

Date: Mon, 6 Apr 2009 23:50:51 GMT (817kb)

Title: Drag force on an impurity below the superfluid critical velocity in a

quasi-one-dimensional Bose-Einstein condensate

Authors: Andrew G. Sykes, Matthew J. Davis, and David C. Roberts

Categories: cond-mat.quant-gas

Comments: 7 pages (including supplementary material)

\\

The existence of frictionless flow below a critical velocity for obstacles

moving in a superfluid is well established in the context of the mean-field

Gross-Pitaevskii theory. We calculate the next order correction due to quantum

and thermal fluctuations and find a non-zero force acting on a delta-function

impurity moving through a quasi-one-dimensional Bose-Einstein condensate at all

subcritical velocities and at all temperatures. The force occurs due to an

imbalance in the Doppler shifts of reflected quantum fluctuations from either

side of the impurity. Our calculation is based on a consistent extension of

Bogoliubov theory to second order in the interaction strength, and finds new

analytical solutions to the Bogoliubov-de Gennes equations for a gray soliton.

Our results raise questions regarding the quantum dynamics in the formation of

persistent currents in superfluids.

\\ ( http://arxiv.org/abs/0904.0995 , 817kb)

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arXiv:0904.1160

Date: Tue, 7 Apr 2009 14:53:59 GMT (514kb)

Title: Spin dynamics and structure formation in a spin-1 condensate in a

magnetic field

Authors: Jordi Mur-Petit (UCL)

Categories: cond-mat.quant-gas

Comments: 8 pages, 5 figures

\\

We study the dynamics of a trapped spin-1 condensate in a magnetic field.

First, we analyze the homogeneous system, for which the dynamics can be

understood in terms of orbits in phase space, and we solve analytically for the

dynamical evolution of the populations of the various Zeeman components of the

homogeneous system. This result is then applied via a Local Density

Approximation to trapped quasi-1D condensates. Our analysis of the trapped

system in a magnetic field shows that both mean-field and Zeeman regimes are

simultaneously present, and argue that the border between these two regions is

where spin domains and phase defects are generated. We finally propose a method

to experimentally tune the position of this border.

\\ ( http://arxiv.org/abs/0904.1160 , 514kb)

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arXiv:0904.1199

Date: Tue, 7 Apr 2009 20:22:24 GMT (1561kb)

Title: Theory of domain formation in inhomogeneous ferromagnetic dipolar

condensates

Authors: Jay D. Sau, S. R. Leslie, D. M. Stamper-Kurn, Marvin L. Cohen

Categories: cond-mat.quant-gas

Comments: 26 pages, 8 figures

\\

Recent experimental studies of $^{87}$Rb spinor Bose Einstein condensates

have shown the existence of a magnetic field driven quantum phase transition

accompanied by structure formation on the ferromagnetic side of the transition.

In this theoretical study we examine the dynamics of the unstable modes

following the transition taking into account the effects of the trap,

non-linearities, finite temperature and dipole-dipole interactions. Starting

from an initial state which includes quantum fluctuations, we attempt to make

quantitative comparisons with recent experimental data on this system and

estimate the contribution of quantum zero-point fluctuations to the domain

formation. Finally, using the strong anisotropy of the trap, we propose ways to

observe directly the effects of dipole-dipole interactions on the spinor

condensate dynamics.

\\ ( http://arxiv.org/abs/0904.1199 , 1561kb)

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arXiv:0904.1333

Date: Wed, 8 Apr 2009 14:11:01 GMT (2129kb)

Title: Spectral Functions and rf Response of Ultracold Fermionic Atoms

Authors: R. Haussmann, M. Punk, and W. Zwerger

Categories: cond-mat.quant-gas

Comments: 15 pages, 5 figures, revtex 4

\\

We present a calculation of the spectral functions and the associated rf

response of ultracold fermionic atoms near a Feshbach resonance. The single

particle spectra are peaked at energies that can be modelled by a modified BCS

dispersion. Even at very low temperatures, however, their width is comparable

to their energy and thus the standard BCS description of fermionic superfluids

by well-defined Bogoliubov quasiparticles does not apply. The structure of the

broad excitation spectrum of the unitary gas at infinite scattering length

agrees with recent momentum-resolved rf spectra near the critical temperature.

A detailed comparison is made with momentum integrated, locally resolved rf

spectra of the unitary gas at arbitrary temperatures and shows very good

agreement between theory and experiment. The pair size defined from the width

of these spectra is found to coincide with that obtained from the leading

gradient corrections to the effective field theory of the superfluid.

\\ ( http://arxiv.org/abs/0904.1333 , 2129kb)

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arXiv:0904.1348

Date: Wed, 8 Apr 2009 14:10:21 GMT (41kb)

Title: Quantum Phase Transitions in a Dimerized Bose-Hubbard Model: A DMRG

Study

Authors: Anasuya Kundu and Swapan K Pat

Categories: cond-mat.quant-gas

Comments: 5 pages, 4 figures

Journal-ref: Europhysics Letters 85, 43001 (2009)

\\

We investigate the phase diagram of a dimerized Bose-Hubbard model, using

density matrix renormalization group technique. We find a new phase, which is

the coexistence of superfluid and bond-wave phases, due to the effect of

dimerization. Experimentally dimerization in optical lattice can be realized by

using two counter propagating laser beams of different wavelengths. Apart from

the conventional superfluid to Mott insulator transition, we find a new quantum

phase transition: from superfluid-bond-wave to Mott insulator-bond wave phase.

Our study suggests a rich phase diagram which can be easily probed.

\\ ( http://arxiv.org/abs/0904.1348 , 41kb)

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arXiv:0901.3345 (*cross-listing*)

Date: Wed, 21 Jan 2009 20:50:35 GMT (470kb)

Title: Quantum dynamics of instability-induced pulsations of a Bose-Einstein

condensate in an optical lattice

Authors: Uttam Shrestha, Juha Javanainen, and Janne Ruostekoski

Categories: cond-mat.other quant-ph

\\

We study the dynamics of a Bose-Einstein condensate in a one-dimensional

optical lattice in the limit of weak atom-atom interactions, including an

approximate model for quantum fluctuations. A pulsating dynamical instability

in which atoms periodically collect together and subsequently disperse back

into the initial homogeneous state may occur in the time evolution. We take

into account the quantum fluctuations within the truncated Wigner

approximation. We observe that the quasiperiodic behavior still persists for a

single realization that represents a typical experimental outcome, but ensemble

averages show various manifestations of quantum fluctuations. Quantum effects

become more prominent when the effective interaction strength is increased.

\\ ( http://arxiv.org/abs/0901.3345 , 470kb)

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arXiv:0904.1532

Date: Thu, 9 Apr 2009 13:50:26 GMT (875kb)

Title: In-situ Observation of Incompressible Mott-Insulating Domains of

Ultracold Atomic Gases

Authors: Nathan Gemelke, Xibo Zhang, Chen-Lung Hung, Cheng Chin

Categories: cond-mat.quant-gas

\\

We present a direct measurement of the density profile of a two-dimensional

Mott Insulator formed by ultracold atoms in an optical lattice. High resolution

absorption imaging is used to probe the "wedding-cake" structure of a trapped

gas as it crosses the boundary from a unit-filled Mott insulating phase to the

superfluid phase at finite temperature. Detailed analysis of images yields

measurements of temperature and local compressibility; for the latter we

observe a strong suppression deep in the Mott-insulating phase, which is

recovered for the superfluid and normal phases. Furthermore, we measure

spatially resolved fluctuations in the local density, showing a suppression of

fluctuations in the insulator. Results are consistent with the

fluctuation-dissipation theorem for insulator, superfluid and normal gas.

\\ ( http://arxiv.org/abs/0904.1532 , 875kb)

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arXiv:0904.1552

Date: Thu, 9 Apr 2009 15:46:57 GMT (366kb)

Title: Pair-supersolid phase in a bilayer system of dipolar lattice bosons

Authors: C. Trefzger, C. Menotti, and M. Lewenstein

Categories: cond-mat.other

Comments: 4 pages, 4 figures

\\

The competition between tunneling and interactions in bosonic lattice models

generates a whole variety of different quantum phases. While, in the presence

of a single species interacting via on-site interaction, the phase diagram

presents only superfluid or Mott insulating phases, for long-range interactions

or multiple species, exotic phases such as supersolid (SS) or pair-superfluid

(PSF) appear. In this work, we show for the first time that the co-existence of

effective multiple species and long-range interactions leads to the formation

of a novel pair-supersolid (PSS) phase, namely a supersolid of composites. We

propose a possible implementation with dipolar bosons in a bilayer

two-dimensional optical lattice.

\\ ( http://arxiv.org/abs/0904.1552 , 366kb)

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arXiv:0904.1569

Date: Thu, 9 Apr 2009 17:01:21 GMT (6964kb)

Title: Induced interaction and crystallization of self-localized impurity

fields in a Bose-Einstein condensate

Authors: Sergio Rica and David C. Roberts

Categories: cond-mat.quant-gas

Comments: 16 pages, 9 figures, (33 fig. files including subfigures)

\\

We model the behavior of N classical impurity fields immersed in a larger

Bose-Einstein condensate by N+1 coupled nonlinear Schr\"odinger equations in 1,

2, and 3 space dimensions. We discuss the stability of the uniform miscible

system and show the importance of surface tension for self localization of the

impurity fields. We derive analytically the attractive tail of

impurity-impurity interaction due to mediation by the underlying condensate.

Assuming all impurity fields interact with the same strength, we explore

numerically the resulting phase diagram, which contains four phases: I) all

fields are miscible; II) the impurity fields are miscible with each other but

phase separate from the condensate as a single bubble; III) the localized

impurity fields stay miscible with the condensate, but not with each other; and

IV) the impurity fields phase separate from the condensate and each other,

forming a crystalline structure within a bubble. Finally, we argue that the

crystalline phases maintain their superfluid behavior, i.e. they possess a

nonclassical rotational inertia, which, combined with lattice order, is a

characteristic of supersolidity.

\\ ( http://arxiv.org/abs/0904.1569 , 6964kb)

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The replacements:

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arXiv:0901.0694

replaced with revised version Fri, 3 Apr 2009 16:35:18 GMT (203kb)

Title: Independent Control of Scattering Lengths in Multicomponent Quantum

Gases

Authors: Peng Zhang, Pascal Naidon and Masahito Ueda

Categories: physics.atom-ph cond-mat.other quant-ph

Comments: 4pages, 3figures

\\ ( http://arxiv.org/abs/0901.0694 , 203kb)

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arXiv:0903.5343

replaced with revised version Fri, 3 Apr 2009 02:05:24 GMT (315kb)

Title: Repulsive Fermi gas in a harmonic trap: Ferromagnetism and spin textures

Authors: L. J. LeBlanc, J. H. Thywissen, A. A. Burkov, A. Paramekanti

Categories: cond-mat.quant-gas

Comments: 9 pages, 4 figures (minor typos in text+fig corrected)

\\ ( http://arxiv.org/abs/0903.5343 , 315kb)

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arXiv:0903.5459

replaced with revised version Sat, 4 Apr 2009 18:03:02 GMT (607kb)

Title: Nonequilibrium Josephson oscillations in Bose-Einstein condensates

without dissipation

Authors: Mauricio Trujillo Martinez, Anna Posazhennikova, and Johann Kroha

Categories: cond-mat.quant-gas cond-mat.other

Comments: 4 pages, 4 figures

\\ ( http://arxiv.org/abs/0903.5459 , 607kb)

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arXiv:0810.1733

replaced with revised version Tue, 7 Apr 2009 08:43:33 GMT (1045kb)

Title: Generalized Dynamical Mean-Field Theory for Bose-Fermi Mixtures in

Optical Lattices

Authors: I. Titvinidze, M. Snoek, and W. Hofstetter

Categories: cond-mat.other

Comments: 12+ pages 6 figures

Journal-ref: Phys. Rev. B 79, 144506 (2008)

DOI: 10.1103/PhysRevB.79.144506

\\ ( http://arxiv.org/abs/0810.1733 , 1045kb)

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arXiv:0810.5503

replaced with revised version Thu, 9 Apr 2009 11:55:54 GMT (431kb)

Title: Determination of atomic scattering lengths from measurements of

molecular binding energies near Feshbach resonances

Authors: A. D. Lange, K. Pilch, A. Prantner, F. Ferlaino, B. Engeser, H.-C.

Naegerl, R. Grimm, and C. Chin

Categories: cond-mat.other cond-mat.quant-gas physics.atom-ph

Comments: 6 pages, 4 figures

Journal-ref: Phys. Rev. A 79, 013622 (2009)

\\ ( http://arxiv.org/abs/0810.5503 , 431kb)

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arXiv:0903.1276

replaced with revised version Thu, 9 Apr 2009 11:38:58 GMT (1126kb)

Title: Evidence for Universal Four-Body States Tied to an Efimov Trimer

Authors: F. Ferlaino, S. Knoop, M. Berninger, W. Harm, J. P. D'Incao, H.-C.

N\"agerl, and R. Grimm

Categories: cond-mat.other cond-mat.quant-gas physics.atom-ph quant-ph

Comments: 4 pages, 4 figures

Journal-ref: Phys. Rev. Lett. 102, 140401 (2009)

\\ ( http://arxiv.org/abs/0903.1276 , 1126kb)

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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 =========================================================================Received on Fri May 29 2009 - 08:38:24 EST

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