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

Date: Sun, 20 Sep 2009 10:16:46 +1000

Date: Sun, 20 Sep 2009 10:16:46 +1000

Dear subscribers,

Jacopo Sabbatini compiled this week's abstracts. There are 13 new preprints and

7 replacements.

------------------------------------------------------------------------------

\\

arXiv:0908.2026

Date: Fri, 14 Aug 2009 14:35:15 GMT (157kb)

Title: Strongly interacting trapped bosons yield fragmented transverse states

in the crossover to low dimension

Authors: Uwe R. Fischer and Philipp Bader

Categories: cond-mat.quant-gas

Comments: 5 pages of RevTex4, 3 figures

\\

We investigate trapped bosonic gases approaching the crossover to lower

dimension from the coherent (Bose-Einstein condensate) side, along the

transverse confining direction. Using a variational analysis, we derive the

fragmentation of the Bose-Einstein condensate into two mutually incoherent

macroscopically occupied field operator modes, upon increasing a dimensionless

interaction measure beyond a critical value.

\\ ( http://arxiv.org/abs/0908.2026 , 157kb)

------------------------------------------------------------------------------

\\

arXiv:0908.2071

Date: Fri, 14 Aug 2009 14:12:38 GMT (76kb,D)

Title: Search for broad Feshbach resonances in the 6Li-40K mixture

Authors: T.G. Tiecke, M.R. Goosen, A. Ludewig, S.D. Gensemer, S. Kraft,

S.J.J.M.F. Kokkelmans, and J.T.M. Walraven

Categories: cond-mat.quant-gas

Comments: 4 pages, 2 figures

\\

We explore the widths of interspecies Feshbach resonances in a mixture of the

fermionic quantum gases 6Li and 40K. Experimentally, we obtain the asymmetric

lineshape of the interspecies elastic cross section by measuring the

distillation rate of 6Li atoms from an optically-trapped 6Li-40K mixture as a

function of magnetic field. This provides us with the first experimental

determination of the width of a resonance in this mixture, Delta B=1.5(5) G,

being one of the broadest. We present an extended version of the Asymptotic

Bound-state Model (ABM) and show that this model offers a convenient method to

estimate the width and position of a large number of Feshbach resonances. Our

results offer good perspectives for the observation of universal crossover

physics in this mixture.

\\ ( http://arxiv.org/abs/0908.2071 , 76kb)

------------------------------------------------------------------------------

\\

arXiv:0908.2018

Date: Fri, 14 Aug 2009 06:43:18 GMT (324kb)

Title: Quantum interference in the time-of-flight distribution

Authors: Md. Manirul Ali and Hsi-Sheng Goan

Categories: quant-ph

Comments: 5 figures, Accepted by Journal of Physics A: Mathematical and

Theoretical

\\

We propose a scheme to experimentally observe matter-wave interference in the

time domain, specifically in the arrival-time or the time-of-flight (TOF)

distribution for atomic BEC Schrodinger-cat state represented by superposition

of macroscopically separated wave packets in space. This is in contrast to

interference in space at a fixed time observed in reported BEC experiments. We

predict and quantify the quantum interference in the TOF distribution

calculated from the modulus of the quantum probability current density (rather

than the TOF distributions obtained from a purely classical or semi-classical

treatment in many reported experiments). The interference and hence the

coherence in the quantum TOF signal disappears in the large-mass limit. Our

scheme has the potential to probe the validity of various other theoretical

approaches (Phys. Rep. 338, 353 (2000)) of calculating the quantum arrival time

distribution.

\\ ( http://arxiv.org/abs/0908.2018 , 324kb)

------------------------------------------------------------------------------

\\

arXiv:0908.2159

Date: Sat, 15 Aug 2009 04:25:43 GMT (25kb)

Title: Universal Four-Component Fermi Gas in One Dimension

Authors: Yusuke Nishida and Dam T. Son

Categories: cond-mat.quant-gas

Comments: 4 pages, 1 figure

Report-no: MIT-CTP 4055, INT-PUB-09-038

\\

A four-component Fermi gas in one dimension with a short-range four-body

interaction is shown to exhibit a one-dimensional analog of the BCS-BEC

crossover. Its low-energy physics is governed by a Tomonaga-Luttinger liquid

with three spin gaps. The spin gaps are exponentially small in the weak

coupling limit when it is due to the BCS-like pairing, while they are large in

the strong coupling ("BEC") limit because of the formation of tightly-bound

tetramers. We investigate the sound velocity and the gap spectrum in the

BCS-BEC crossover. Exact relationships valid in our system are also discussed.

\\ ( http://arxiv.org/abs/0908.2159 , 25kb)

------------------------------------------------------------------------------

\\

arXiv:0908.2172

Date: Mon, 17 Aug 2009 07:04:34 GMT (1881kb)

Title: Vortex structures in rotating Bose-Einstein condensates

Authors: S. I. Matveenko, D. Kovrizhin, S. Ouvry, G. V. Shlyapnikov

Categories: cond-mat.quant-gas cond-mat.stat-mech

Comments: 15 pages, 9 figures

\\

We present an analytical solution for the vortex lattice in a rapidly

rotating trapped Bose-Einstein condensate (BEC) in the lowest Landau level and

discuss deviations from the Thomas-Fermi density profile. This solution is

exact in the limit of a large number of vortices and is obtained for the cases

of circularly symmetric and narrow channel geometries. The latter is realized

when the trapping frequencies in the plane perpendicular to the rotation axis

are different from each other and the rotation frequency is equal to the

smallest of them. This leads to the cancelation of the trapping potential in

the direction of the weaker confinement and makes the system infinitely

elongated in this direction. For this case we calculate the phase diagram as a

function of the interaction strength and rotation frequency and identify the

order of quantum phase transitions between the states with a different number

of vortex rows.

\\ ( http://arxiv.org/abs/0908.2172 , 1881kb)

------------------------------------------------------------------------------

\\

arXiv:0908.2323

Date: Mon, 17 Aug 2009 11:02:54 GMT (11kb)

Title: Particle fluctuations in nonuniform and trapped Bose gases

Authors: V.I. Yukalov

Categories: cond-mat.quant-gas cond-mat.stat-mech

Comments: Latex file, 16 pages

Journal-ref: Laser Phys. Lett. 6 (2009) 688-695

\\

The problem of particle fluctuations in arbitrary nonuniform systems with

Bose-Einstein condensate is considered. This includes the case of trapped Bose

atoms. It is shown that the correct description of particle fluctuations for

any nonuniform system of interacting atoms always results in thermodynamically

normal fluctuations.

\\ ( http://arxiv.org/abs/0908.2323 , 11kb)

------------------------------------------------------------------------------

\\

arXiv:0908.2478

Date: Tue, 18 Aug 2009 02:09:05 GMT (111kb)

Title: Quarter-filled supersolid and solid phases in the extended Bose-Hubbard

model

Authors: Kwai-Kong Ng, Y.C. Chen, Y.C. Tzeng

Categories: cond-mat.other

Comments: 6 pages, 9 figures

\\

We numerically study the ground state phase diagram of the two-dimensional

hard-core Bose-Hubbard model with nearest ($V_1$) and next nearest neighbor

($V_2$) repulsions. In particular, we focus on the quarter-filled phases where

one supersolid and two solid phases are observed. Using both canonical and

grand canonical quantum Monte Carlo (QMC) methods and a mean field calculation,

we confirm the existence of a \textit{commensurate} supersolid at quarter boson

filling. The nature of the commensurate supersolid will be discussed. Only one

kind of the supersolid phase is found energetically stable despite of the two

possible diagonal long range orderings for the solid phase. The competition

between the two solid phases manifests as a first order phase transition around

$2 V_2\sim V_1$. The change of order parameters as functions of the chemical

function is also presented.

\\ ( http://arxiv.org/abs/0908.2478 , 111kb)

------------------------------------------------------------------------------

\\

arXiv:0908.2485

Date: Tue, 18 Aug 2009 12:39:19 GMT (908kb)

Title: Time-dependent currents of 1D bosons in an optical lattice

Authors: Johannes Schachenmayer, Guido Pupillo and Andrew J. Daley

Categories: cond-mat.quant-gas

Comments: 18 pages, 10 figures, submitted to New J. Phys

\\

We analyse the time-dependence of currents in a 1D Bose gas in an optical

lattice. For a 1D system, the stability of currents induced by accelerating the

lattice exhibits a broad crossover as a function of the magnitude of the

acceleration, and the strength of the inter-particle interactions. This differs

markedly from mean-field results in higher dimensions. Using the infinite Time

Evolving Block Decimation algorithm, we characterise this crossover by making

quantitative predictions for the time-dependent behaviour of the currents and

their decay rate. We also compute the time-dependence of quasi-condensate

fractions which can be measured directly in experiments. We compare our results

to calculations based on phase-slip methods, finding agreement with the scaling

as the particle density increases, but with significant deviations near unit

filling.

\\ ( http://arxiv.org/abs/0908.2485 , 908kb)

------------------------------------------------------------------------------

\\

arXiv:0908.2551

Date: Tue, 18 Aug 2009 12:15:36 GMT (789kb,D)

Title: Finite temperature dynamics of a single vortex in a Bose-Einstein

condensate: Equilibrium precession and rotational symmetry breaking

Authors: T. M. Wright, A. S. Bradley, R. J. Ballagh,

Categories: cond-mat.quant-gas

Comments: 21 pages, 10 figures

\\

We consider a finite temperature Bose-Einstein condensate in a quasi-2D trap

containing a single precessing vortex. We find that such a configuration arises

naturally as an ergodic equilibrium of the projected Gross-Pitaevskii equation,

when constrained to a finite conserved angular momentum. In an isotropic

trapping potential the condensation of the classical field into an off-axis

vortex state breaks the rotational symmetry of the system. We present a

methodology to identify the condensate and the Goldstone mode associated with

the broken rotational symmetry in the classical-field model. We also examine

the variation in vortex trajectories and thermodynamic parameters of the field

as the energy of the microcanonical field simulation is varied.

\\ ( http://arxiv.org/abs/0908.2551 , 789kb)

------------------------------------------------------------------------------

\\

arXiv:0908.2781

Date: Wed, 19 Aug 2009 16:16:50 GMT (135kb)

Title: The spin evolution of spin-3 $^{52}$Cr Bose-Einstein condensate

Authors: Yanzhang He

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

Comments: 5 pages, 3 figures

\\

The spin evolution of a Bose-Einstein condensate starting from a mixture of

two or three groups of $^{52}$Cr (spin-3) atoms in an optical trap has been

studied theoretically. The initial state is so chosen that the system does not

distinguish up and down. In this choice, the deviation caused by the

single-mode approximation is reduced. Moreover, since the particle number is

given very small (N=20), the deviation caused by the neglect of the long-range

dipole force is also reduced. Making use of these two simplifications, a

theoretical calculation beyond the mean field theory is performed. The

numerical results are help to evaluate the unknown strength $g_0$.

\\ ( http://arxiv.org/abs/0908.2781 , 135kb)

------------------------------------------------------------------------------

\\

arXiv:0908.2792

Date: Wed, 19 Aug 2009 17:59:01 GMT (202kb)

Title: Dynamical quantum phase transition of a two-component Bose-Einstein

condensate in an optical lattice

Authors: Anssi Collin, Jani-Petri Martikainen, Jonas Larson

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

Comments: 8 pages, 8 figures

\\

We study dynamics of a two-component Bose-Einstein condensate where the two

components are coupled via an optical lattice. In particular, we focus on the

dynamics as one drives the system through a critical point of a first order

phase transition characterized by a jump in the internal populations. Solving

the time-dependent Gross-Pitaevskii equation, we analyze; breakdown of

adiabaticity, impact of non-linear atom-atom scattering, and the role of a

harmonic trapping potential. Our findings demonstrate that the phase transition

is resilient to both contact interaction between atoms and external trapping

confinement.

\\ ( http://arxiv.org/abs/0908.2792 , 202kb)

------------------------------------------------------------------------------

\\

arXiv:0908.2930

Date: Thu, 20 Aug 2009 14:23:37 GMT (112kb)

Title: The dynamics of coherence between coupled and decoupled one-dimensional

quasicondensates

Authors: R.G. Scott and D.A.W. Hutchinson

Categories: cond-mat.quant-gas

\\

We reproduce the sub-exponential decoherence of one-dimensional

quasicondensates observed in recent experiments. Counter-intuitively, the

quasicondensates may decohere even when stongly coupled, if the temperature is

large enough or the peak density is low enough to allow significant density

fluctuations. We also propose an experiment to investigate the growth of

coherence between two initially incoherent quasicondensates. We predict that

the coherence will rise on a much slower timescale, and the final coherence

again depends strongly on the density fluctuations.

\\ ( http://arxiv.org/abs/0908.2930 , 112kb)

------------------------------------------------------------------------------

\\

arXiv:0908.2976

Date: Thu, 20 Aug 2009 18:42:44 GMT (1445kb,D)

Title: Classical versus quantum dynamics of the atomic Josephson junction

Authors: G.J. Krahn and D.H.J. O'Dell

Categories: cond-mat.quant-gas

Comments: 31 pages, 14 figures

\\

We compare the classical (mean-field) dynamics with the quantum dynamics of

atomic Bose-Einstein condensates in double-well potentials. The quantum

dynamics are computed using a simple scheme based upon the Raman-Nath

equations. Two different methods for exciting a non-equilbrium state are

considered: an asymmetry between the wells which is suddenly removed, and a

periodic time oscillating asymmetry. The first method generates wave packets

that lead to collapses and revivals of the expectation values of the

macroscopic variables, and we calculate the time scale for these revivals. The

second method permits the excitation of a single energy eigenstate of the

many-particle system, including Schroedinger cat states. We also discuss a band

theory interpretation of the energy level structure of an asymmetric

double-well, thereby identifying analogies to Bloch oscillations and Bragg

resonances. Both the Bloch and Bragg dynamics are purely quantum and are not

contained in the mean-field treatment.

\\ ( http://arxiv.org/abs/0908.2976 , 1445kb)

------------------------------------------------------------------------------

The replacements:

------------------------------------------------------------------------------

\\

arXiv:0904.4815

replaced with revised version Mon, 17 Aug 2009 07:18:18 GMT (756kb)

Title: Hopping modulation in a one-dimensional Fermi-Hubbard Hamiltonian

Authors: F. Massel, M. J. Leskinen, P. Torma

Categories: cond-mat.quant-gas

Comments: 4 pages, 5 figures; minor changes in the text, updated references;

Journal-ref: Phys. Rev. Lett. 103, 066404 (2009)

\\ ( http://arxiv.org/abs/0904.4815 , 756kb)

------------------------------------------------------------------------------

\\

arXiv:0906.4359

replaced with revised version Sun, 16 Aug 2009 18:02:57 GMT (891kb)

Title: Systematic reduction of sign errors in many-body problems:

generalization of self-healing diffusion Monte Carlo to excited states

Authors: Fernando A. Reboredo

Categories: cond-mat.str-el cond-mat.quant-gas

Comments: New version with two new figures. Several formulas of intermediate

steps in the analytical derivations have been added. The review reports and

replies with a summary of changes are included in the source pdf files with

nicer figures are also included in the source

\\ ( http://arxiv.org/abs/0906.4359 , 891kb)

------------------------------------------------------------------------------

\\

arXiv:0908.0608

replaced with revised version Sat, 15 Aug 2009 09:47:58 GMT (137kb)

Title: Ground state of a tightly bound composite dimer immersed in a Fermi Sea

Authors: Christophe Mora (LPA), Fr\'ed\'eric Chevy (LKB - Lhomond)

Categories: cond-mat.quant-gas

Comments: 11 pages; 3 figures

\\ ( http://arxiv.org/abs/0908.0608 , 137kb)

------------------------------------------------------------------------------

\\

arXiv:0805.4447

replaced with revised version Sun, 16 Aug 2009 21:39:46 GMT (202kb)

Title: Sign of tunnel coupling in barrier-separated Bose-Einstein condensates

and stability of double-ring systems

Authors: Joachim Brand, Tania J. Haigh, and Ulrich Z\"ulicke

Categories: quant-ph

Comments: 4 pages, comment on Phys. Rev. Lett. 98, 050401 (2007)

[arXiv:quant-ph/0609133v2]

\\ ( http://arxiv.org/abs/0805.4447 , 202kb)

------------------------------------------------------------------------------

\\

arXiv:0901.0694

replaced with revised version Mon, 17 Aug 2009 12:32:38 GMT (76kb)

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 , 76kb)

------------------------------------------------------------------------------

\\

arXiv:0904.0115

replaced with revised version Mon, 17 Aug 2009 11:52:39 GMT (71kb)

Title: Dynamics of an inhomogeneous quantum phase transition

Authors: Jacek Dziarmaga and Marek M. Rams

Categories: quant-ph cond-mat.mes-hall cond-mat.quant-gas cond-mat.stat-mech

cond-mat.str-el

Comments: 7 pages, 4 figures; longer version with improved presentation;

\\ ( http://arxiv.org/abs/0904.0115 , 71kb)

------------------------------------------------------------------------------

\\

arXiv:0906.0962

replaced with revised version Mon, 17 Aug 2009 02:56:40 GMT (114kb)

Title: Quantum-limited metrology and Bose-Einstein condensates

Authors: Sergio Boixo, Animesh Datta, Matthew J. Davis, Anil Shaji, Alexandre

B. Tacla and Carlton M. Caves

Categories: quant-ph

Comments: 32 pages, 1 figure

\\ ( http://arxiv.org/abs/0906.0962 , 114kb)

------------------------------------------------------------------------------

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

*
This archive was generated by hypermail 2.2.0
: Thu Sep 24 2009 - 15:47:52 EST
*