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

Date: Fri, 10 Sep 2010 10:57:41 +1000

Date: Fri, 10 Sep 2010 10:57:41 +1000

Dear subscribers,

This week's selection was compiled by Geoff Lee, and contains 31 new

abstracts and 18 replacements.

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arXiv:0910.5337 (*cross-listing*)

Date: Wed, 28 Oct 2009 10:51:07 GMT (242kb)

Date (revised v2): Thu, 15 Jul 2010 15:48:27 GMT (574kb)

Title: Fluctuations and stochastic processes in one-dimensional many-body

quantum systems

Authors: H.-P. Stimming, N. J. Mauser, J. Schmiedmayer, and I. E. Mazets

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

Comments: 4 pages (revtex4), 4 color figures. Text substantially rewritten, two

figures added

Journal-ref: Phys. Rev. Lett. 105, 015301 (2010)

DOI: 10.1103/PhysRevLett.105.015301

\\

We study the fluctuation properties of a one-dimensional many-body quantum

system composed of interacting bosons, and investigate the regimes where

quantum noise or, respectively, thermal excitations are dominant. For the

latter we develop a semiclassical description of the fluctuation properties

based on the Ornstein-Uhlenbeck stochastic process. As an illustration, we

analyze the phase correlation functions and the full statistical distributions

of the interference between two one-dimensional systems, either independent or

tunnel-coupled and compare with the Luttinger-liquid theory.

\\ ( http://arxiv.org/abs/0910.5337 , 574kb)

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arXiv:0912.4493 (*cross-listing*)

Date: Tue, 22 Dec 2009 19:17:24 GMT (229kb)

Date (revised v2): Thu, 15 Jul 2010 16:59:19 GMT (231kb)

Title: Thermalization in a quasi-1D ultracold bosonic gas

Authors: I. E. Mazets and J. Schmiedmayer

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

Comments: revtex4, 3 figures. Final version of the text, accepted for

publication (see journal ref.)

Journal-ref: New J. Phys. 12 (2010) 055023

DOI: 10.1088/1367-2630/12/5/055023

\\

We study the collisional processes that can lead to thermalization in

one-dimensional systems. For two body collisions excitations of transverse

modes are the prerequisite for energy exchange and thermalzation. At very low

temperatures excitations of transverse modes are exponentially suppressed,

thermalization by two body collisions stops and the system should become

integrable. In quantum mechanics virtual excitations of higher radial modes are

possible. These virtually excited radial modes give rise to effective

three-body velocity-changing collisions which lead to thermalization. We show

that these three-body elastic interactions are suppressed by pairwise quantum

correlations when approaching the strongly correlated regime. If the relative

momentum $k$ is small compared to the two-body coupling constant $c$ the

three-particle scattering state is suppressed by a factor of $(k/c)^{12}$,

which is proportional to $\gamma ^{12}$, that is to the square of the

three-body correlation function at zero distance in the limit of the

Lieb-Liniger parameter $\gamma \gg 1$. This demonstrates that in one

dimensional quantum systems it is not the freeze-out of two body collisions but

the strong quantum correlations which ensures absence of thermalization on

experimentally relevant time scales.

\\ ( http://arxiv.org/abs/0912.4493 , 231kb)

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arXiv:1007.1458

Date: Thu, 8 Jul 2010 20:00:35 GMT (295kb)

Title: Dimensional crossover of a boson gas in multilayers

Authors: P. Salas, F.J. Sevilla, M. Fortes, M. de Llano, A. Camacho, and M.A.

Sol\'is

Categories: cond-mat.quant-gas

Comments: Ten pages, nine figures

\\

We obtain the thermodynamic properties for a non-interacting Bose gas

constrained on multilayers modeled by a periodic Kronig-Penney delta potential

in one direction and allowed to be free in the other two directions. We report

Bose-Einstein condensation (BEC) critical temperatures, chemical potential,

internal energy, specific heat, and entropy for different values of a

dimensionless impenetrability $P\geqslant 0$ between layers. The BEC critical

temperature $T_{c}$ coincides with the ideal gas BEC critical temperature

$T_{0}$ when $P=0$ and rapidly goes to zero as $P$ increases to infinity for

any finite interlayer separation. The specific heat $C_{V}$ \textit{vs} $T$ for

finite $P$ and plane separation $a$ exhibits one minimum and one or two maxima

in addition to the BEC, for temperatures larger than $T_{c}$ which highlights

the effects due to particle confinement. Then we discuss a distinctive

dimensional crossover of the system through the specific heat behavior driven

by the magnitude of $P$. For $T<T_{c}$ the crossover is revealed by the change

in the slope of $\log C_{V}(T)$ and when $T>T_{c}$, it is evidenced by a broad

minimum in $C_{V}(T)$.

\\ ( http://arxiv.org/abs/1007.1458 , 295kb)

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arXiv:1007.1475

Date: Thu, 8 Jul 2010 21:41:36 GMT (276kb)

Title: Vortices and dynamics in trapped Bose-Einstein condensates

Authors: Alexander L. Fetter

Categories: cond-mat.quant-gas

Comments: Accepted for publication in Journal of Low Temperature Physics,

conference proceedings: Symposia on Superfluids under Rotation (Lammi,

Finland, April 2010)

\\

I review the basic physics of ultracold dilute trapped atomic gases, with

emphasis on Bose-Einstein condensation and quantized vortices. The hydrodynamic

form of the Gross-Pitaevskii equation (a nonlinear Schr{\"o}dinger equation)

illuminates the role of the density and the quantum-mechanical phase. One

unique feature of these experimental systems is the opportunity to study the

dynamics of vortices in real time, in contrast to typical experiments on

superfluid $^4$He. I discuss three specific examples (precession of single

vortices, motion of vortex dipoles, and Tkachenko oscillations of a vortex

array). Other unusual features include the study of quantum turbulence and the

behavior for rapid rotation, when the vortices form dense regular arrays.

Ultimately, the system is predicted to make a quantum phase transition to

various highly correlated many-body states (analogous to bosonic quantum Hall

states) that are not superfluid and do not have condensate wave functions. At

present, this transition remains elusive. Conceivably, laser-induced synthetic

vector potentials can serve to reach this intriguing phase transition.

\\ ( http://arxiv.org/abs/1007.1475 , 276kb)

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arXiv:1007.1480

Date: Thu, 8 Jul 2010 22:13:46 GMT (1561kb,D)

Title: Dysprosium magneto-optical traps

Authors: Seo Ho Youn, Mingwu Lu, Ushnish Ray, and Benjamin L. Lev

Categories: physics.atom-ph quant-ph

Comments: 13 pages, 12 figures, follow up material to Phys. Rev. Lett. 104,

063001 (2010)

\\

Magneto-optical traps (MOTs) of highly magnetic lanthanides open the door to

explorations of novel phases of strongly correlated matter such as lattice

supersolids and quantum liquid crystals. We recently reported the first MOTs of

the five high abundance isotopes of the most magnetic atom, dysprosium.

Described here are details of the experimental technique employed for

repumper-free Dy MOTs containing up to half a billion atoms. Extensive

characterization of the MOTs' properties---population, temperature, loading,

metastable decay dynamics, trap dynamics---is provided.

\\ ( http://arxiv.org/abs/1007.1480 , 1561kb)

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arXiv:1007.1506

Date: Fri, 9 Jul 2010 03:54:20 GMT (39kb)

Title: Induced interaction in a spin-polarized Fermi gas

Authors: Zeng-Qiang Yu and Lan Yin

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

Comments: 6 pages, 2 figures

Journal-ref: Phys. Rev. A 82, 013605 (2010)

DOI: 10.1103/Phys.Rev.A82.013605

\\

We study the effect of the induced interaction on the superfluidtransition

temperature of a spin-polarized Fermi gas. In the BCS limit, the polarization

is very small in the superfluid state, and the effect of the induced

interaction is almost the same as in the spin-balanced case. The temperature Tt

and the polarization Pt of the tricritical point are both reduced from

mean-field results by a factor about 2.22. This reduction is also significant

beyond the BCS limit. In the unitary limit, we find (Pt,Tt/TF)=(0.42,0.16), in

comparison with mean-field and experimental results.

\\ ( http://arxiv.org/abs/1007.1506 , 39kb)

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arXiv:1007.1534

Date: Fri, 9 Jul 2010 09:03:00 GMT (105kb)

Title: Stability of attractive bosonic cloud with van der Waals interaction

Authors: Anindya Biswas, Tapan Kumar Das, Luca Salasnich and Barnali

Chakrabarti

Categories: cond-mat.quant-gas

Comments: 9 pages, 5 figures

\\

We investigate the structure and stability of Bose-Einstein condensate of

$^{7}$Li atoms with realistic van der Waals interaction by using the potential

harmonic expansion method. Besides the known low-density metastable solution

with contact delta function interaction, we find a stable branch at a higher

density which corresponds to the formation of an atomic cluster. Comparison

with the results of non-local effective interaction is also presented. We

analyze the effect of trap size on the transition between the two branches of

solutions. We also compute the loss rate of a Bose condensate due to two- and

three-body collisions.

\\ ( http://arxiv.org/abs/1007.1534 , 105kb)

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arXiv:1007.1657 (*cross-listing*)

Date: Fri, 9 Jul 2010 19:47:47 GMT (102kb,D)

Title: Driving quantized vortices with quantum vacuum fluctuations

Authors: Fran\c{c}ois Impens, Ana M. Contreras-Reyes, Paulo A. Maia Neto, Diego

A. R. Dalvit, Romain Gu\'erout, Astrid Lambrecht, Serge Reynaud

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

Comments: 4 pages, 2 figures

\\

We propose to use a rotating corrugated material plate in order to stir,

through the Casimir-Polder interaction, quantized vortices in an harmonically

trapped Bose-Einstein condensate. The emergence of such vortices within the

condensate appears as a genuine signature of non-trivial geometry effects on

the electromagnetic vacuum fluctuations which fully exploits the superfluid

nature of the sample. We calculate the exact non-perturbative Casimir-Polder

potential, valid to all orders of the corrugation amplitude, felt by the atoms

in front of the grating and show that the resulting quantum vacuum torque is

strong enough to provide a contactless transfer of angular momentum to the

condensate and generate quantized vortices under realistic experimental

conditions at separation distances around 3 microns.

\\ ( http://arxiv.org/abs/1007.1657 , 102kb)

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arXiv:1007.1796 (*cross-listing*)

Date: Sun, 11 Jul 2010 19:55:41 GMT (9kb)

Title: Localization of Multi-Dimensional Wigner Distributions

Authors: Elliott H. Lieb and Yaron Ostrover

Categories: math-ph math.MP quant-ph

Comments: seven pages, latex

MSC-class: 81S30, 81P15, 81P16

\\

A well known result of P. Flandrin states that a Gaussian uniquely maximizes

the integral of the Wigner distribution over every centered disc in the phase

plane. While there is no difficulty in generalizing this result to

higher-dimensional poly-discs, the generalization to balls is less obvious. In

this note we provide such a generalization.

\\ ( http://arxiv.org/abs/1007.1796 , 9kb)

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arXiv:1007.1847

Date: Mon, 12 Jul 2010 08:55:31 GMT (1377kb)

Title: Unifying treatment of nonequilibrium and unstable dynamics of cold

bosonic atom system with time-dependent order parameter in Thermo Filed

Dynamics

Authors: Y. Nakamura and Y. Yamanaka

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

Comments: 10 pages, 6 figures

\\

The coupled equations which describe the temporal evolution of the

Bose-Einstein condensed system are derived in the framework of nonequilibrium

Thermo Field Dynamics. The key element is that they are not the naive

assemblages of presumable equations, but are the self-consistent ones derived

by appropriate renormalization conditions. While the order parameter is

time-dependent, an explicit quasiparticle picture is constructed by a

time-dependent expansion. Our formulation is valid even for the system with a

unstable condensate, and describes the condensate decay caused by the Landau

instability as well as by the dynamical one.

\\ ( http://arxiv.org/abs/1007.1847 , 1377kb)

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arXiv:1007.1853

Date: Mon, 12 Jul 2010 09:44:30 GMT (31kb,D)

Title: Comment on "Feshbach-Einstein Condensates" by V. G. Rousseau and P. J.

H. Denteneer

Authors: Mar\'ia Eckholt, Tommaso Roscilde

Categories: cond-mat.quant-gas

Comments: 1+epsilon page, 1 figure

\\

In a recent paper (Phys. Rev. Lett. 102, 015301 (2009), arXiv:0810.3763)

Rousseau and Denteneer claim that an unconventional "super-Mott" (SM) phase is

realized by bosons trapped in an optical lattice close to a Feshbach resonance

with a molecular state. The supposed SM phase, observed via quantum Monte Carlo

(QMC) simulations of an atom-molecule Bose-Hubbard model, is an incompressible

phase developing spontaneous atomic/molecular supercurrents which are perfectly

anticorrelated. Here we show that the identification of this phase is based on

a misinterpretation of the estimators of superfluidity in QMC, which break down

in the presence of coherent atom/molecule conversion. Our conclusion is that

the supposed SM phase is in fact a fully normal insulator.

\\ ( http://arxiv.org/abs/1007.1853 , 31kb)

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arXiv:1007.1884

Date: Mon, 12 Jul 2010 12:28:01 GMT (85kb)

Title: Feedback Cooling of a Single Neutral Atom

Authors: Markus Koch, Christian Sames, Alexander Kubanek, Matthias Apel,

Maximilian Balbach, Alexei Ourjoumtsev, Pepijn W.H. Pinkse and Gerhard Rempe

Categories: quant-ph

Comments: 4 pages, 4 figures

\\

We demonstrate feedback cooling of the motion of a single rubidium atom

trapped in a high-finesse optical resonator to a temperature of about 160 \mu

K. Time-dependent transmission and intensity-correlation measurements prove the

reduction of the atomic position uncertainty. The feedback increases the 1/e

storage time into the one second regime, 30 times longer than without feedback.

Feedback cooling therefore rivals state-of-the-art laser cooling, but with the

advantages that it requires less optical access and exhibits less optical

pumping.

\\ ( http://arxiv.org/abs/1007.1884 , 85kb)

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arXiv:1007.1892 (*cross-listing*)

Date: Mon, 12 Jul 2010 12:48:01 GMT (19kb)

Title: The ground state of the polar alkali-Strontium molecules: potential

energy curve and permanent dipole moment

Authors: Romain Gu\'erout (LKB - Jussieu), Mireille Aymar (LAC), Olivier Dulieu

(LAC)

Categories: physics.atm-clus quant-ph

\\

In this study, we investigate the structure of the polar alkali-Strontium

diatomic molecules as possible candidates for the realization of samples of new

species of ultracold polar molecules. Using a quantum chemistry approach based

on Effective Core Potentials and Core Polarization Potentials, we model these

systems as effective three valence electron systems, allowing for calculation

of electronic properties with Full Configuration Interaction. The potential

curve and the permanent dipole moment of the $^2\Sigma^+$ ground state are

determined as functions of the internuclear distances for LiSr, NaSr, KSr,

RbSr, and CsSr molecules. These molecules are found to exhibit a significant

permanent dipole moment, though smaller than those of the alkali-Rb molecules.

\\ ( http://arxiv.org/abs/1007.1892 , 19kb)

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arXiv:1007.1898

Date: Mon, 12 Jul 2010 13:24:08 GMT (3858kb)

Title: Vibrational stabilization of ultracold KRb molecules. A comparative

study

Authors: Mamadou Ndong and Christiane P. Koch

Categories: physics.atom-ph

Comments: 11 pages, 10 figures, 17 graphs

\\

The transfer of weakly bound KRb molecules from levels just below the

dissociation threshold into the vibrational ground state with shaped laser

pulses is studied. Optimal control theory is employed to calculate the pulses.

The complexity of modelling the molecular structure is successively increased

in order to study the effects of the long-range behavior of the excited state

potential, resonant spin-orbit coupling and singlet-triplet mixing.

\\ ( http://arxiv.org/abs/1007.1898 , 3858kb)

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arXiv:1007.1899

Date: Mon, 12 Jul 2010 13:29:53 GMT (201kb)

Title: Quantum imaging of spin states in optical lattices

Authors: James Douglas and Keith Burnett

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

\\

We investigate imaging of the spatial spin distribution of atoms in optical

lattices using non-resonant light scattering. We demonstrate how scattering

spatially correlated light from the atoms can result in spin state images with

enhanced spatial resolution. Furthermore, we show how using spatially

correlated light can lead to direct measurement of the spatial correlations of

the atomic spin distribution.

\\ ( http://arxiv.org/abs/1007.1899 , 201kb)

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arXiv:1007.2015

Date: Tue, 13 Jul 2010 00:43:41 GMT (1211kb)

Title: The Design and Validation of the Quantum Mechanics Conceptual Survey

Authors: S. B. McKagan, K. K. Perkins, C. E. Wieman

Categories: physics.ed-ph

Comments: Submitted to Physical Review Special Topics: Physics Education

Research

\\

The Quantum Mechanics Conceptual Survey (QMCS) is a 12-question survey of

students' conceptual understanding of quantum mechanics. It is intended to be

used to measure the relative effectiveness of different instructional methods

in modern physics courses. In this paper we describe the design and validation

of the survey, a process that included observations of students, a review of

previous literature and textbooks and syllabi, faculty and student interviews,

and statistical analysis. We also discuss issues in the development of specific

questions, which may be useful both for instructors who wish to use the QMCS in

their classes and for researchers who wish to conduct further research of

student understanding of quantum mechanics. The QMCS has been most thoroughly

tested in, and is most appropriate for assessment of (as a posttest only),

sophomore-level modern physics courses. We also describe testing with students

in junior quantum courses and graduate quantum courses, from which we conclude

that the QMCS may be appropriate for assessing junior quantum courses, but is

not appropriate for assessing graduate courses. One surprising result of our

faculty interviews is a lack of faculty consensus on what topics should be

taught in modern physics, which has made designing a test that is valued by a

majority of physics faculty more difficult than expected.

\\ ( http://arxiv.org/abs/1007.2015 , 1211kb)

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arXiv:1007.2027

Date: Tue, 13 Jul 2010 03:30:10 GMT (789kb)

Title: Spin textures in condensates with large dipole moments

Authors: J. A. M. Huhtam\"aki, M. Takahashi, T. P. Simula, T. Mizushima, and K.

Machida

Categories: cond-mat.quant-gas

Comments: 9 pages, 6 figures

Journal-ref: Phys. Rev. A 81, 063623 (2010)

DOI: 10.1103/PhysRevA.81.063623

\\

We have solved numerically the ground states of a Bose-Einstein condensate in

the presence of dipolar interparticle forces using a semiclassical approach.

Our motivation is to model, in particular, the spontaneous spin textures

emerging in quantum gases with large dipole moments, such as 52Cr or Dy

condensates, or ultracold gases consisting of polar molecules. For a

pancake-shaped harmonic (optical) potential, we present the ground state phase

diagram spanned by the strength of the nonlinear coupling and dipolar

interactions. In an elongated harmonic potential, we observe a novel helical

spin texture. The textures calculated according to the semiclassical model in

the absence of external polarizing fields are predominantly analogous to

previously reported results for a ferromagnetic F = 1 spinor Bose-Einstein

condensate, suggesting that the spin textures arising from the dipolar forces

are largely independent of the value of the quantum number F or the origin of

the dipolar interactions.

\\ ( http://arxiv.org/abs/1007.2027 , 789kb)

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arXiv:1007.2056

Date: Tue, 13 Jul 2010 09:32:49 GMT (1584kb)

Title: Topology-induced phase transitions in quantum spin Hall lattices

Authors: D. Bercioux, N. Goldman, D.F. Urban

Categories: cond-mat.mes-hall cond-mat.quant-gas

\\

Physical phenomena driven by topological properties, such as the quantum Hall

effect, have the appealing feature to be robust with respect to external

perturbations. Lately, a new class of materials has emerged manifesting their

topological properties at room temperature and without the need of external

magnetic fields. These topological insulators are band insulators with large

spin-orbit interactions and exhibit the quantum spin-Hall (QSH) effect. Here we

investigate the transition between QSH and normal insulating phases under

topology deformations of a two-dimensional lattice. We demonstrate that the QSH

phase present in the honeycomb lattice looses its robustness as the occupancy

of extra lattice sites is allowed. Furthermore, we propose a method for

verifying our predictions with fermionic cold atoms in optical lattices. In

this context, the spin-orbit interaction is engineered via an appropriate

synthetic gauge field.

\\ ( http://arxiv.org/abs/1007.2056 , 1584kb)

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arXiv:1007.2136

Date: Tue, 13 Jul 2010 16:37:16 GMT (595kb)

Title: Improved detection of small atom numbers through image processing

Authors: C. F. Ockeloen, A. F. Tauschinsky, R. J. C. Spreeuw, and S. Whitlock

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

Comments: 4 pages, 3 figures

\\

We demonstrate improved detection of small trapped atomic ensembles through

advanced post-processing and optimal analysis of absorption images. A fringe

removal algorithm reduces imaging noise to the fundamental photon-shot-noise

level and proves beneficial even in the absence of fringes. A

maximum-likelihood estimator is then derived for optimal atom-number estimation

and is applied to real experimental data to measure the population differences

and intrinsic atom shot-noise between spatially separated ensembles each

comprising between 10 and 2000 atoms. The combined techniques improve our

signal-to-noise by a factor of 3, to a minimum resolvable population difference

of 17 atoms, close to our ultimate detection limit.

\\ ( http://arxiv.org/abs/1007.2136 , 595kb)

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arXiv:1007.2189 (*cross-listing*)

Date: Tue, 13 Jul 2010 20:05:09 GMT (372kb)

Title: Two-stage melting of solids in strongly interacting Rydberg atoms

Authors: Hendrik Weimer, Hans Peter B\"uchler

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

Comments: 4 pages, 3 figures

\\

We analyze the ground state properties of a one-dimensional cold atomic

system in a lattice, where Rydberg excitations are created by an external laser

drive. In the classical limit, the ground state is characterized by a complete

devil's staircase for the commensurate solid structures of Rydberg excitations.

Using perturbation theory and a mapping onto an effective low energy

Hamiltonian, we find a transition of these commensurate solids into a floating

solid with algebraic correlations. For stronger quantum fluctuations the

floating solid eventually melts within a second quantum phase transition and

the ground state becomes paramagnetic.

\\ ( http://arxiv.org/abs/1007.2189 , 372kb)

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arXiv:1007.2245

Date: Wed, 14 Jul 2010 03:29:45 GMT (37kb)

Title: Particle-hole symmetric localization in optical lattices using time

modulated random on-site potentials

Authors: Yue Zou, Ryan Barnett, Gil Refael

Categories: cond-mat.quant-gas cond-mat.dis-nn

Comments: 7 pages, 5 figures

\\

The random hopping models exhibit many fascinating features, such as

diverging localization length and density of states as energy approaches the

bandcenter, due to its particle-hole symmetry. Nevertheless, such models are

yet to be realized experimentally because the particle-hole symmetry is easily

destroyed by diagonal disorder. Here we propose that a pure random hopping

model can be effectively realized in ultracold atoms by modulating a disordered

onsite potential in particular frequency ranges. This idea is motivated by the

recent development of the phenomena called "dynamical localization" or

"coherent destruction of tunneling". Investigating the application of this idea

in one dimension, we find that if the oscillation frequency of the disorder

potential is gradually increased from zero to infinity, one can tune a

non-interacting system from an Anderson insulator to a random hopping model

with diverging localization length at the band center, and eventually to a

uniform-hopping tight-binding model.

\\ ( http://arxiv.org/abs/1007.2245 , 37kb)

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arXiv:1007.2329 (*cross-listing*)

Date: Wed, 14 Jul 2010 13:41:50 GMT (117kb)

Title: Dynamics of bisolitonic matter waves in a Bose-Einstein condensate

subjected to an atomic beam splitter and gravity

Authors: Alain Moise Dikande, Isaiah Ndifon Ngek and Joseph Ebobenow

Categories: nlin.PS cond-mat.quant-gas physics.atom-ph physics.optics

Comments: 10 pages, 26 figures, to appear in Modern Physics Letters B (Accepted

12 July, 2010)

\\

A theoretical scheme for an experimental implementation involving bisolitonic

matter waves from an attractive Bose-Einstein condensate, is considered within

the framework of a non-perturbative approach to the associate Gross-Pitaevskii

equation. The model consists of a single condensate subjected to an expulsive

harmonic potential creating a double-condensate structure, and a gravitational

potential that induces atomic exchanges between the two overlapping post

condensates. Using a non-isospectral scattering transform method, exact

expressions for the bright-matter-wave bisolitons are found in terms of

double-lump envelopes with the co-propagating pulses displaying more or less

pronounced differences in their widths and tails depending on the mass of atoms

composing the condensate.

\\ ( http://arxiv.org/abs/1007.2329 , 117kb)

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arXiv:1007.2342 (*cross-listing*)

Date: Wed, 14 Jul 2010 14:18:02 GMT (1713kb)

Title: Spontaneous breaking of spatial and spin symmetry in spinor condensates

Authors: M. Scherer, B. L\"ucke, G. Gebreyesus, O. Topic, F. Deuretzbacher, W.

Ertmer, L. Santos, J.J. Arlt, C. Klempt

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

Comments: 5 pages, 4 figures

\\

Parametric amplification of quantum fluctuations constitutes a fundamental

mechanism for spontaneous symmetry breaking. In our experiments, a spinor

condensate acts as a parametric amplifier of spin modes, resulting in a twofold

spontaneous breaking of spatial and spin symmetry in the amplified clouds. Our

experiments permit a precise analysis of the amplification in specific spatial

Bessel-like modes, allowing for the detailed understanding of the double

symmetry breaking. On resonances that create vortex-antivortex superpositions,

we show that the cylindrical spatial symmetry is spontaneously broken, but

phase squeezing prevents spin-symmetry breaking. If, however, nondegenerate

spin modes contribute to the amplification, quantum interferences lead to

spin-dependent density profiles and hence spontaneously-formed patterns in the

longitudinal magnetization.

\\ ( http://arxiv.org/abs/1007.2342 , 1713kb)

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arXiv:1007.2344 (*cross-listing*)

Date: Wed, 14 Jul 2010 14:27:04 GMT (2266kb,D)

Title: Emerging Bosons with Three-Body Interactions from Spin-1 Atoms in

Optical Lattices

Authors: Leonardo Mazza and Matteo Rizzi and Maciej Lewenstein and J.Ignacio

Cirac

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

Comments: 17 pages, 13 figures

\\

We study two many-body systems of bosons interacting via an infinite

three-body contact repulsion in a lattice: a pairs quasi-condensate induced by

correlated hopping and the discrete version of the Pfaffian wavefunction. We

propose to experimentally realise systems characterized by such interaction by

means of a proper spin-1 lattice Hamiltonian: spin degrees of freedom are

locally mapped into occupation numbers of emerging bosons, in a fashion similar

to spin-1/2 and hardcore bosons. Such a system can be realized with ultracold

spin-1 atoms in a Mott Insulator with filling-factor one. The high versatility

of these setups allows us to engineer spin-hopping operators breaking the SU(2)

symmetry, as needed to approximate interesting bosonic Hamiltonians with

three-body hardcore constraint. For this purpose we combine bichromatic

spin-independent superlattices and Raman transitions to induce a different

hopping rate for each spin orientation. Finally, we illustrate how our setup

could be used to experimentally realize the first setup, i.e. the transition to

a pairs quasi-condensed phase of the emerging bosons. We also report on a route

towards the realization of a discrete bosonic Pfaffian wavefunction and list

some open problems to reach this goal.

\\ ( http://arxiv.org/abs/1007.2344 , 2266kb)

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arXiv:1007.2408

Date: Wed, 14 Jul 2010 19:59:13 GMT (328kb,D)

Title: Nonlinear interference in a mean-field quantum model

Authors: Gilbert Reinisch and Vidar Gudmundsson

Categories: cond-mat.mes-hall cond-mat.quant-gas

Comments: RevTeX (pdfLaTeX), 7 pages with 5 png-figures included

\\

Using similar nonlinear stationary mean-field models for Bose-Einstein

Condensation of cold atoms and interacting electrons in a Quantum Dot, we

propose to describe the original many-particle ground state as a one-particle

statistical mixed state of the nonlinear eigenstates whose weights are provided

by the eigenstate non-orthogonality. We search for physical grounds in the

interpretation of our two main results, namely, quantum-classical nonlinear

transition and interference between nonlinear eigenstates.

\\ ( http://arxiv.org/abs/1007.2408 , 328kb)

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arXiv:1007.2416

Date: Wed, 14 Jul 2010 20:02:08 GMT (727kb)

Title: Quantum localization without disorder in interacting Bose-Einstein

condensates

Authors: Roberto Franzosi, Salvatore M. Giampaolo, Fabrizio Illuminati

Categories: cond-mat.quant-gas

Comments: 4 pages, 4 figures

\\

We discuss the possibility of exponential quantum localization in systems of

ultracold bosonic atoms with repulsive interactions in open optical lattices

without disorder. We show that exponential localization occur in the maximally

excited state of the lowest energy band. We establish the conditions under

which the presence of the upper energy bands can be neglected, determine the

successive stages and the quantum phase boundaries at which localization

occurs, and discuss how to detect it experimentally by visibility measurements.

The discussed mechanism is a bona fide type of quantum localization, solely due

to the interplay between nonlinearity and a bounded energy spectrum. In

particular, it does not require the presence of random disorder or other local

sources of noise, in striking contrast with Anderson localization.

\\ ( http://arxiv.org/abs/1007.2416 , 727kb)

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\\

arXiv:1007.2544 (*cross-listing*)

Date: Thu, 15 Jul 2010 12:43:05 GMT (73kb)

Title: The three-site Bose-Hubbard model subject to atom losses: the boson-pair

dissipation channel and failure of the mean-field approach

Authors: V. S. Shchesnovich and D. S. Mogilevtsev

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

Comments: 9 pages; 3 figures in color; submitted to PRA

\\

We employ the perturbation series expansion for derivation of the reduced

master equations for the three-site Bose-Hubbard model subject to strong atom

losses from the central site. The model describes a condensate trapped in a

triple-well potential subject to externally controlled removal of atoms. We

find that the $\pi$-phase state of the coherent superposition between the side

wells decays via two dissipation channels, the single-boson channel (similar to

the externally applied dissipation) and the boson-pair channel. The quantum

derivation is compared to the classical adiabatic elimination within the

mean-field approximation. We find that the boson-pair dissipation channel is

not captured by the mean-field model, whereas the single-boson channel is

described by it. Moreover, there is a matching condition between the zero-point

energy bias of the side wells and the nonlinear interaction parameter which

separates the regions where either the single-boson or the boson-pair

dissipation channel dominate. Our results indicate that the $M$-site

Bose-Hubbard models, for $M>2$, subject to atom losses may require an analysis

which goes beyond the usual mean-field approximation for correct description of

their dissipative features. This is an important result in view of the recent

experimental works on the single site addressability of condensates trapped in

optical lattices.

\\ ( http://arxiv.org/abs/1007.2544 , 73kb)

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\\

arXiv:1007.2568 (*cross-listing*)

Date: Thu, 15 Jul 2010 14:19:06 GMT (37kb)

Title: Atomic number fluctuations in a mixture of two spinor condensates

Authors: Jie Zhang, Z. F. Xu, L. You and Yunbo Zhang

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

Comments: 5 pages, 2 figures, in press PRA

\\

We study particle number fluctuations in the quantum ground states of a

mixture of two spin-1 atomic condensates when the interspecies spin-exchange

coupling interaction $c_{12}\beta$ is adjusted. The two spin-1 condensates

forming the mixture are respectively ferromagnetic and polar in the absence of

an external magnetic (B-) field. We categorize all possible ground states using

the angular momentum algebra and compute their characteristic atom number

fluctuations, focusing especially on the the AA phase (when $ c_{12}\beta >0$),

where the ground state becomes fragmented and atomic number fluctuations

exhibit drastically different features from a single stand alone spin-1 polar

condensate. Our results are further supported by numerical simulations of the

full quantum many-body system.

\\ ( http://arxiv.org/abs/1007.2568 , 37kb)

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\\

arXiv:1007.2591 (*cross-listing*)

Date: Thu, 15 Jul 2010 15:43:54 GMT (588kb)

Title: Probing magnetic order in ultracold lattice gases

Authors: G. De Chiara, O. Romero-Isart and A. Sanpera

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

\\

The simulation of quantum magnetism with ultracold lattice gases is one of

the next challenges in the field of ultracold atoms. We propose a method to

measure directly the order parameter of non trivial antiferromagnetic quantum

phases in a non demolishing way. This atom-light interface gives access to

spatially resolved spin correlations. Such probing scheme allows one to

univocally characterize strongly correlated magnetic systems simulated with

ultracold atoms in optical lattices. As a proof of principle, we apply our

method to detect the complete phase diagram of the rotational invariant spin-1

chain.

\\ ( http://arxiv.org/abs/1007.2591 , 588kb)

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\\

arXiv:1007.2625

Date: Thu, 15 Jul 2010 18:10:27 GMT (29kb)

Title: Observation of Universal Temperature Scaling in the Quantum Viscosity of

a Unitary Fermi Gas

Authors: C. Cao, E. Elliott, J. Joseph, H. Wu, J. Petricka, T. Schaefer, and J.

E.Thomas

Categories: cond-mat.quant-gas

Comments: 4 pages, 2 figures

\\

A Fermi gas of atoms tuned near a Feshbach resonance should obey universal

hydrodynamics, where the shear viscosity and other transport coefficients are

universal functions of the density and temperature. At temperatures well above

the superfluid transition, the viscosity has a universal quantum scale

$p_T^3/\hbar^2$, where $p_T$ is the thermal momentum. We observe the expansion

of a unitary Fermi gas in this regime and show that the slowing of the dynamics

with increasing temperature $T$ is explained by a shear viscosity that scales

precisely as $T^{3/2}$. These results are important for measurement of the

shear viscosity just above the critical temperature, where the ratio of the

shear viscosity to the entropy density is expected to exhibit a minimum that

can be compared to a recent conjecture regarding perfect normal fluids.

\\ ( http://arxiv.org/abs/1007.2625 , 29kb)

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\\

arXiv:1007.2638

Date: Thu, 15 Jul 2010 19:47:34 GMT (782kb)

Title: Collisional-inhomogeneity-induced generation of matter-wave dark

solitons

Authors: C. Wang, P.G. Kevrekidis, T.P. Horikis and D.J. Frantzeskakis

Categories: cond-mat.quant-gas nlin.PS

Comments: 8 pages, 5 Figures, Physics Letters A (in press)

\\

We propose an experimentally relevant protocol for the controlled generation

of matter-wave dark solitons in atomic Bose-Einstein condensates (BECs). In

particular, using direct numerical simulations, we show that by switching-on a

spatially inhomogeneous (step-like) change of the s-wave scattering length, it

is possible to generate a controllable number of dark solitons in a

quasi-one-dimensional BEC. A similar phenomenology is also found in the

two-dimensional setting of "disk-shaped" BECs but, as the solitons are subject

to the snaking instability, they decay into vortex structures. A detailed

investigation of how the parameters involved affect the emergence and evolution

of solitons and vortices is provided.

\\ ( http://arxiv.org/abs/1007.2638 , 782kb)

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The replacements:

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arXiv:0905.3384 (*cross-listing*)

replaced with revised version Fri, 9 Jul 2010 06:27:20 GMT (462kb)

Title: Phase space representation of quantum dynamics

Authors: Anatoli Polkovnikov

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

Comments: 92 pages, typos corrected, published version

Journal-ref: Annals of Phys. 325, 1790 (2010)

DOI: 10.1016/j.aop.2010.02.006

\\ ( http://arxiv.org/abs/0905.3384 , 462kb)

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\\

arXiv:1006.3008

replaced with revised version Fri, 9 Jul 2010 13:17:49 GMT (132kb)

Title: Comparing cavity and ordinary laser cooling

Authors: Tony Blake, Andreas Kurcz, and Almut Beige

Categories: quant-ph

Comments: 11 pages, 8 figures, substantially revised version, submitted to

Journal of Modern Optics (Special Issue on New cooling mechanisms for atoms

and molecules)

\\ ( http://arxiv.org/abs/1006.3008 , 132kb)

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\\

arXiv:1003.1403

replaced with revised version Fri, 9 Jul 2010 19:57:03 GMT (360kb)

Title: Quantum chaos and thermalization in gapped systems

Authors: Marcos Rigol and Lea F. Santos

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

Comments: 8 pages, 8 figures, as published

Journal-ref: Phys. Rev. A 82, 011604(R) (2010)

DOI: 10.1103/PhysRevA.82.011604

\\ ( http://arxiv.org/abs/1003.1403 , 360kb)

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\\

arXiv:0912.3559 (*cross-listing*)

replaced with revised version Fri, 9 Jul 2010 20:00:06 GMT (2189kb,D)

Title: Topological states in two-dimensional optical lattices

Authors: Tudor D. Stanescu, Victor Galitski and S. Das Sarma

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

Comments: 29 pages, 34 figures (references and new section added; published

version)

Journal-ref: Phys. Rev. A 82, 013608 (2010)

DOI: 10.1103/PhysRevA.82.013608

\\ ( http://arxiv.org/abs/0912.3559 , 2189kb)

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\\

arXiv:1004.4134

replaced with revised version Mon, 12 Jul 2010 14:33:08 GMT (231kb)

Title: Oscillating solitons in a three component BEC

Authors: Piotr Szankowski, Eryk Infeld, Marek Trippenbach, George Rowlands

Categories: cond-mat.quant-gas

Comments: 5 pages, 4 figures

\\ ( http://arxiv.org/abs/1004.4134 , 231kb)

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\\

arXiv:0906.4584

replaced with revised version Mon, 12 Jul 2010 23:22:51 GMT (222kb)

Title: Phases of a bilayer Fermi gas

Authors: Yusuke Nishida

Categories: cond-mat.quant-gas nucl-th

Comments: 5 pages, 5 figures; (v2) stability of trimer is emphasized; (v3)

published version

Report-no: MIT-CTP 4048

Journal-ref: Phys. Rev. A 82, 011605(R) (2010)

DOI: 10.1103/PhysRevA.82.011605

\\ ( http://arxiv.org/abs/0906.4584 , 222kb)

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\\

arXiv:1006.0181 (*cross-listing*)

replaced with revised version Tue, 13 Jul 2010 10:04:50 GMT (197kb,D)

Title: The two faces of quantum sound

Authors: C. Barcelo, L.J. Garay, G. Jannes

Categories: gr-qc cond-mat.quant-gas

Comments: 12 pages, 4 figures; v2: 1 reference added, discussion expanded

(secs. V.C-D,VI), some other minor changes, this version accepted for

publication in PRD

\\ ( http://arxiv.org/abs/1006.0181 , 197kb)

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\\

arXiv:1007.0840 (*cross-listing*)

replaced with revised version Tue, 13 Jul 2010 11:01:43 GMT (1083kb)

Title: Entanglement Spectrum Identifying Transition from Vortex Liquid to

Vortex Lattice

Authors: Zhao Liu, Hong-Li Guo, Vlatko Vedral and Heng Fan

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

Comments: 4 pages, 5 figures, comments are welcome

\\ ( http://arxiv.org/abs/1007.0840 , 1083kb)

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\\

arXiv:1007.1743

replaced with revised version Tue, 13 Jul 2010 13:29:58 GMT (696kb)

Title: Dynamical instability of a spin spiral in an interacting Fermi gas as a

probe of the Stoner transition

Authors: G.J. Conduit and Ehud Altman

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

\\ ( http://arxiv.org/abs/1007.1743 , 696kb)

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\\

arXiv:1003.2757

replaced with revised version Wed, 14 Jul 2010 01:29:09 GMT (639kb)

Title: Spontaneous inhomogeneous phases in ultracold dipolar Fermi gases

Authors: Kai Sun and Congjun Wu and S. Das Sarma

Categories: cond-mat.quant-gas

Comments: 6 pages, 3 figures, new references added

\\ ( http://arxiv.org/abs/1003.2757 , 639kb)

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\\

arXiv:1005.4076

replaced with revised version Wed, 14 Jul 2010 10:27:33 GMT (188kb)

Title: Observation of a two-dimensional Fermi gas of atoms

Authors: Kirill Martiyanov, Vasiliy Makhalov, Andrey Turlapov

Categories: cond-mat.quant-gas

\\ ( http://arxiv.org/abs/1005.4076 , 188kb)

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\\

arXiv:1001.1918

replaced with revised version Wed, 14 Jul 2010 11:05:53 GMT (22kb)

Title: Controlled hole doping of a Mott insulator of ultracold fermionic atoms

Authors: Andre Eckardt and Maciej Lewenstein

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

Comments: 4-5 pages, accepted for publication as a Rapid Communication in

Physical Review A

\\ ( http://arxiv.org/abs/1001.1918 , 22kb)

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\\

arXiv:1007.0922 (*cross-listing*)

replaced with revised version Wed, 14 Jul 2010 15:13:24 GMT (1760kb,D)

Title: Atom-light crystallization of BECs in multimode cavities: Nonequilibrium

classical and quantum phase transitions, emergent lattices, supersolidity,

and frustration

Authors: Sarang Gopalakrishnan, Benjamin L. Lev, Paul M. Goldbart

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

Comments: 34 pages, 13 figures; follow up to Nat. Phys. 5, 845 (2009)

\\ ( http://arxiv.org/abs/1007.0922 , 1760kb)

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\\

arXiv:0910.1803

replaced with revised version Wed, 14 Jul 2010 16:15:25 GMT (424kb,D)

Title: Pi-phases in balanced fermionic superfluids on spin-dependent optical

lattices

Authors: I. Zapata and B. Wunsch and N. T. Zinner and E. Demler

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

Comments: 4.2 pages, 4 figures, revised version, accepted by PRL

\\ ( http://arxiv.org/abs/0910.1803 , 424kb)

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\\

arXiv:1005.0428

replaced with revised version Thu, 15 Jul 2010 13:17:13 GMT (2318kb)

Title: An Artificial Frustrated System: Cold Atoms in 2D Triangular Optical

Lattice

Authors: Yao-Hua Chen, Wei Wu, Hong-Shuai Tao, and Wu-Ming Liu

Categories: cond-mat.quant-gas

\\ ( http://arxiv.org/abs/1005.0428 , 2318kb)

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\\

arXiv:1003.4887

replaced with revised version Thu, 15 Jul 2010 13:42:56 GMT (32kb)

Title: Identification of the critical temperature from non-equilibrium

time-dependent quantities

Authors: Eugenio Lippiello and Alessandro Sarracino

Categories: cond-mat.stat-mech

Comments: 6 pages, 10 figures

Journal-ref: EPL 90 (2010) 60001

\\ ( http://arxiv.org/abs/1003.4887 , 32kb)

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\\

arXiv:1003.4790 (*cross-listing*)

replaced with revised version Thu, 15 Jul 2010 14:13:07 GMT (83kb)

Title: Hard-core Bose-Fermi mixture in one-dimensional split traps

Authors: Xiaolong L\"u, Xiangguo Yin, Yunbo Zhang

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

Comments: 6 pages, 4 figures, PRA in press

Journal-ref: Phys. Rev. A 81, 043607 (2010)

DOI: 10.1103/PhysRevA.81.043607

\\ ( http://arxiv.org/abs/1003.4790 , 83kb)

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\\

arXiv:1004.3060

replaced with revised version Thu, 15 Jul 2010 15:56:45 GMT (1484kb)

Title: Controlling the transverse instability of dark solitons and nucleation

of vortices by a potential barrier

Authors: Manjun Ma, R. Carretero-Gonzalez, P. G. Kevrekidis, D. J.

Frantzeskakis, and B. A. Malomed

Categories: cond-mat.quant-gas nlin.PS

Comments: 10 pages, 7 figures. To appear on Phys. Rev. A, 2010

\\ ( http://arxiv.org/abs/1004.3060 , 1484kb)

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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 Wed Oct 20 2010 - 09:28:33 EST

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