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

Date: Mon, 25 May 2009 08:41:19 +1000

Date: Mon, 25 May 2009 08:41:19 +1000

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

Dear subscribers,

We again have Andy Ferris to thank for this week's update. There are 32 new

preprints and 14 replacements in this mailing.

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arXiv:0903.4713

Date: Thu, 26 Mar 2009 22:33:06 GMT (11kb)

Title: Effect of random on-site energies on the critical temperature of a

lattice Bose gas

Authors: Luca Dell'Anna, Stefano Fantoni, Pasquale Sodano, Andrea Trombettoni

Categories: cond-mat.stat-mech cond-mat.dis-nn

Comments: To appear in Laser Physics, issue on the LPHYS'08 conference

(Trondheim, 2008)

\\

We study the effect of random on-site energies on the critical temperature of

a non-interacting Bose gas on a lattice. In our derivation the on-site energies

are distributed according a Gaussian probability distribution function having

vanishing average and variance $v_o2$. By using the replicated action obtained

by averaging on the disorder, we perform a perturbative expansion for the Green

functions of the disordered system. We evaluate the shift of the chemical

potential induced by the disorder and we compute, for $v_o2 << 1$, the

critical temperature for condensation. We find that, for large filling,

disorder slightly enhances the critical temperature for condensation.

\\ ( http://arxiv.org/abs/0903.4713 , 11kb)

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arXiv:0903.4732

Date: Fri, 27 Mar 2009 05:31:16 GMT (577kb)

Title: Creation of Dirac monopoles in spinor Bose-Einstein condensates

Authors: Ville Pietil\"a and Mikko M\"ott\"onen

Categories: cond-mat.other

Comments: 5 pages + 4 pages of supplementary material

\\

We demonstrate theoretically that using standard external magnetic fields,

one can imprint point-like topological defects to the spin texture of a dilute

Bose-Einstein condensate. Symmetries of the condensate order parameter render

this topological defect to be accompanied with a vortex filament corresponding

to the Dirac string of a magnetic monopole. The vorticity in the condensate

coincides with the magnetic field of a magnetic monopole, providing an ideal

analogue to the monopole studied by Dirac.

\\ ( http://arxiv.org/abs/0903.4732 , 577kb)

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arXiv:0903.4784

Date: Fri, 27 Mar 2009 12:19:31 GMT (31kb)

Title: Suppression of selection among broken-symmetry states by

cross-correlated noises in double-well system

Authors: Iurii V. Gudyma, Artur Iu. Maksymov

Categories: cond-mat.stat-mech

Comments: 8 pages, 3 figures

\\

Suppression of selection among broken-symmetry states has been found in

double-well system resulting from two simultaneous correlated white noises, one

additive and the other multiplicative. Symmetry-asymmetry-symmetry transition

is re-entrant as a function of the additive noise intensity for small

multiplicative noise.

\\ ( http://arxiv.org/abs/0903.4784 , 31kb)

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arXiv:0903.4823

Date: Fri, 27 Mar 2009 17:51:53 GMT (1551kb)

Title: Quantum transport through a Tonks-Girardeau gas

Authors: Stefan Palzer, Christoph Zipkes, Carlo Sias, and Michael K\"ohl

Categories: cond-mat.mes-hall

\\

We investigate the propagation of spin impurity atoms through a strongly

interacting one-dimensional Bose gas. The initially well localized impurities

are accelerated by a constant force, very much analogous to electrons subject

to a bias voltage, and propagate as a one-dimensional guided atom laser pulse.

We follow the motion of the impurities in situ and characterize the interaction

induced dynamics. We observe a very complex non-equilibrium dynamics, including

the emergence of large density fluctuations in the remaining Bose gas, and

multiple scattering events leading to dissipation of the impurity's motion.

\\ ( http://arxiv.org/abs/0903.4823 , 1551kb)

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arXiv:0903.4837

Date: Fri, 27 Mar 2009 16:06:51 GMT (1233kb,D)

Title: Experimental demonstration of single-site addressability in a

two-dimensional optical lattice

Authors: Peter W\"urtz, Tim Langen, Tatjana Gericke, Andreas Koglbauer, Herwig

Ott

Categories: cond-mat.other

Comments: 4 pages, 5 figures

\\

We demonstrate single site addressability in a two-dimensional optical

lattice with 600 nm lattice spacing. After loading a Bose-Einstein condensate

in the lattice potential we use a focused electron beam to remove atoms from

selected sites. The patterned structure is subsequently imaged by means of

scanning electron microscopy. This technique allows us to create arbitrary

patterns of mesoscopic atomic ensembles. We find that the patterns are

remarkably stable against tunneling diffusion. Such micro-engineered quantum

gases are a versatile resource for applications in quantum simulation, quantum

optics and quantum information processing with neutral atoms.

\\ ( http://arxiv.org/abs/0903.4837 , 1233kb)

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arXiv:0903.4858

Date: Fri, 27 Mar 2009 17:26:13 GMT (452kb)

Title: Feshbach Resonances and Medium Effects in ultracold atomic Gases

Authors: G. M. Bruun

Categories: cond-mat.other

Comments: Presented at the 5th workshop on Critical Stability, Erice, Italy

13-17 October 2008. 8 pages, 3 figures

DOI: 10.1007/s00601-009-0040-9

\\

We develop an effective low energy theory for multi-channel scattering of

cold atomic alkali atoms with particular focus on Feshbach resonances. The

scattering matrix is expressed in terms of observables only and the theory

allows for the inclusion of many-body effects both in the open and in the

closed channels.

We then consider the frequency and damping of collective modes for Fermi

gases and demonstrate how medium effects significantly increase the scattering

rate determining the nature of the modes. Our results obtained with no fitting

parameters are shown to compare well with experimental data.

\\ ( http://arxiv.org/abs/0903.4858 , 452kb)

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arXiv:0903.4859

Date: Fri, 27 Mar 2009 17:27:21 GMT (145kb)

Title: Controlling Grey Solitons in a Trap

Authors: Ayan Khan, Rajneesh Atre and Prasanta K. Panigrahi

Categories: cond-mat.other

Comments: 4 Pages, 4 Figures

\\

It is pointed out that, the energy and velocity profiles of the recently

observed grey solitons match well with the Lieb mode of the Gross-Pitaevskii

equation. These nonlinear excitations are found to have strong coupling with

the trap at low momenta and hence can be effectively isolated from the

Bogoliubov sound modes, which responds weakly to harmonic confinement. This

strong coupling with the trap also makes the grey soliton amenable for control

and manipulation through both trap modulation and temporal variation of the two

body interaction.

\\ ( http://arxiv.org/abs/0903.4859 , 145kb)

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arXiv:0903.5016

Date: Sun, 29 Mar 2009 01:20:41 GMT (408kb)

Title: Pulsating and persistent vector solitons in a Bose-Einstein condensate

in a lattice upon phase separation instability

Authors: Uttam Shrestha, Juha Javanainen, and Janne Ruostekoski

Categories: cond-mat.other

Comments: submitted to PRL

\\

We study numerically the outcome of the phase separation instability of a

dual-species Bose-Einstein condensate in an optical lattice. When only one

excitation mode is unstable a bound pair of a bright and dark solitons

periodically appears and disappears, whereas for more than one unstable mode a

persistent soliton-antisoliton pair develops.

\\ ( http://arxiv.org/abs/0903.5016 , 408kb)

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arXiv:0903.5153

Date: Mon, 30 Mar 2009 08:57:38 GMT (46kb)

Title: Critical behavior and scaling in trapped systems

Authors: Massimo Campostrini and Ettore Vicari

Categories: cond-mat.stat-mech

Comments: 4 pages, 6 figs

\\

We study the scaling properties of critical particle systems confined by a

potential. Using renormalization-group arguments, we show that their critical

behavior can be cast in the form of a trap-size scaling, resembling finite-size

scaling theory, with a nontrivial trap critical exponent theta, which describes

how the correlation length scales with the trap size l, i.e., $\xi\sim

l^\theta$ at the critical point. theta depends on the universality class of the

transition, the power law of the confining potential, and on the way it is

coupled to the critical modes. We present numerical results for two-dimensional

lattice gas (Ising) models with various types of harmonic traps, which support

the trap-size scaling scenario.

\\ ( http://arxiv.org/abs/0903.5153 , 46kb)

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arXiv:0903.5226

Date: Mon, 30 Mar 2009 14:05:13 GMT (38kb)

Title: Fermion mediated long-range interactions of bosons in the 1D

Bose-Fermi-Hubbard model

Authors: Alexander Mering, Michael Fleischhauer

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

Comments: 4+epsilon pages

\\

The ground-state phase diagram of mixtures of spin polarized fermions and

bosons in a 1D periodic lattice is discussed in the limit of large fermion

hopping. Formally eliminating the fermions gives rise to a long-range

oscillatory interaction between bosons, which is the origin of charge density

waves (CDW). We derive a renormalized effective Hamiltonian for half filling of

fermions that allows an analytic description of the transition from the

insulating Mott-insulator (MI) and CDW phases to a superfluid (SF) phase for

bosons. For non-commensurate boson filling a spatial phase separation (PS)

between incompressible Mott and CDW regions occurs for small hopping

amplitudes. The phase diagram is calculated from the effective model, in

particular the CDW--SF transition is discussed. The analytic predictions agree

well with numerical simulations obtained with the density-matrix

renormalization group. Numerical evidence is given that CDW and SF are

separated by a region with exponentially decaying first-order correlations,

i.e. there is no supersolid phase.

\\ ( http://arxiv.org/abs/0903.5226 , 38kb)

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arXiv:0903.5265

Date: Mon, 30 Mar 2009 17:05:16 GMT (723kb)

Title: Antiferromagnetic Order of Repulsively Interacting Fermions on Optical

lattices

Authors: Tobias Gottwald, Peter van Dongen

Categories: cond-mat.quant-gas

Comments: 4 pages, 3 figures

\\

The N\'eel state in fermionic mixtures of two pseudospin species in an

optical lattice is analyzed at low temperatures. Experimentally it remains a

challenge to demonstrate antiferromagnetic correlations in ultracold fermionic

quantum gases. We find that, while in balanced systems the N\'eel order

parameter can point in any spatial direction, in imbalanced mixtures

antiferromagnetism is strictly perpendicular to the quantization axis (i.e.,

the z-axis). Since, experimentally, one always has to assume some minimal

imbalance this should have important consequences for ongoing experiments.

\\ ( http://arxiv.org/abs/0903.5265 , 723kb)

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arXiv:0903.5019

Date: Sun, 29 Mar 2009 03:38:16 GMT (91kb)

Title: Nonlinear Phenomenology from Quantum Mechanics: Soliton in a Lattice

Authors: Juha Javanainen and Uttam Shrestha

Categories: quant-ph

Comments: 4 pages, 2 figures

Journal-ref: Phys. Rev. Lett. 101, 170405 (2008)

\\

We study a soliton in an optical lattice holding bosonic atoms quantum

mechanically using both an exact numerical solution and quantum Monte Carlo

simulations. The computation of the state is combined with an explicit account

of the measurements of the numbers of the atoms at the lattice sites. In

particular, importance sampling in the quantum Monte Carlo method arguably

produces faithful simulations of individual experiments. Even though the

quantum state is invariant under lattice translations, an experiment may show a

noisy version of the localized classical soliton.

\\ ( http://arxiv.org/abs/0903.5019 , 91kb)

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arXiv:0903.5181

Date: Mon, 30 Mar 2009 11:08:32 GMT (27kb)

Title: Numerical and Analytical Approach to the Quantum Dynamics of Two Coupled

Spins in Bosonic Baths

Authors: Alessandro Sergi, Ilya Sinayskiy, Francesco Petruccione

Categories: quant-ph

\\

The quantum dynamics of a spin chain interacting with multiple bosonic baths

is described in a mixed Wigner-Heisenberg representation. The formalism is

illustrated by simulating the time evolution of the reduced density matrix of

two coupled spins, where each spin is also coupled to its own bath of harmonic

oscillators. In order to prove the validity of the approach, an analytical

solution in the Born-Markov approximation is found. The agreement between the

two methods is shown.

\\ ( http://arxiv.org/abs/0903.5181 , 27kb)

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arXiv:0903.5029

Date: Sun, 29 Mar 2009 08:46:01 GMT (744kb)

Title: Time-of-Flight Signatures of Bosons in a Double Well

Authors: Analabha Roy, Linda E. Reichl

Categories: physics.atom-ph

Comments: 6 Figures

\\

We present analytical and numerical treatments for evaluating the

time-of-flight momentum distribution for the stationary states of a two-boson

system trapped in a quartic double-well potential, paying particular attention

to the Tonks and noninteracting regimes. We find that the time-of-flight

distributions can serve as a valuable tool in profiling the states of this

system, which will be useful in understanding the chaotic dynamics of coherent

quantum controlled excitations of trapped bosons.

\\ ( http://arxiv.org/abs/0903.5029 , 744kb)

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arXiv:0903.5324

Date: Tue, 31 Mar 2009 00:02:19 GMT (25kb)

Title: Evaporative depolarization and spin transport in an ultracold trapped

Fermi gas

Authors: Meera M. Parish and David A. Huse

Categories: cond-mat.quant-gas

Comments: 6 pages, 3 figures

\\

We consider a partially spin-polarized atomic Fermi gas in a

high-aspect-ratio trap, with a flux of predominantly spin-up atoms exiting the

center of the trap. We argue that such a scenario can be produced by

evaporative cooling, and we find that it can result in a substantially

non-equilibrium polarization pattern for typical experimental parameters. We

offer this as a possible explanation for the quantitative discrepancies in

recent experiments on spin-imbalanced unitary Fermi gases.

\\ ( http://arxiv.org/abs/0903.5324 , 25kb)

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arXiv:0903.5343

Date: Tue, 31 Mar 2009 15:40:09 GMT (317kb)

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

\\

We study ferromagnetism in a repulsively interacting two-component Fermi gas

in a harmonic trap at zero net magnetization. Within a local density

approximation, the two components phase-separate beyond a critical interaction

strength, with one species having a higher density at the trap center. The mean

field release energy depends on the interaction strength and contains a sharp

signature of this transition. To go beyond the local density approximation, we

derive an energy functional which includes a term that depends on the local

magnetization gradient and acts as a `surface tension'. Using this energy

functional, we numerically study the energetics of some candidate spin textures

which may be stabilized in a harmonic trapping potential. We find that a

hedgehog state has a lower energy than an `in-out' domain wall state in an

isotropic trap. Upon inclusion of trap anisotropy we find that the hedgehog

magnetization profile gets distorted due to the surface tension term, this

distortion being more apparent for small atom numbers. We estimate that the

magnetic dipole interaction does not play a significant role in this system. We

consider implications for experiments on trapped two-component Fermi systems

such as Li-6 and K-40 gases.

\\ ( http://arxiv.org/abs/0903.5343 , 317kb)

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arXiv:0903.5366

Date: Tue, 31 Mar 2009 04:59:32 GMT (843kb)

Title: Virial expansion for a strongly correlated Fermi gas

Authors: Xia-Ji Liu, Hui Hu and Peter D. Drummond

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

Comments: 4 pages,4 figures

\\

Using a high temperature virial expansion, we present a controllable study of

the thermodynamics of strongly correlated Fermi gases near the BEC-BCS

crossover region. We propose a practical way to determine the expansion

coefficients for both harmonically trapped and homogeneous cases, and calculate

the third order coefficient $b_{3}(T)$ at finite temperatures $T$. At

resonance, a $T$-independent coefficient

$b_{3,\infty}^{\hom}\approx-0.29095295$ is determined in free space. These

results are compared with a recent thermodynamic measurement of $^{6}$Li atoms,

at temperatures below the degeneracy temperature, and with Monte Carlo

simulations.

\\ ( http://arxiv.org/abs/0903.5366 , 843kb)

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arXiv:0903.5371

Date: Tue, 31 Mar 2009 05:46:16 GMT (883kb)

Title: Ultracold Atomic Gases: Novel States of Matter

Authors: L. Mathey, S.-W. Tsai, and A. H. Castro Neto

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

Comments: 43 pages, 17 figures. To appear in the Encyclopedia of Complexity and

Systems Science, Dr. R. A. Meyers (Ed.) (Springer Heidelberg, 2009)

\\

Article to appear in the Encyclopedia of Complexity and Systems Science, Dr.

R. A. Meyers (Ed.) (Springer Heidelberg, 2009).

\\ ( http://arxiv.org/abs/0903.5371 , 883kb)

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arXiv:0903.5459

Date: Tue, 31 Mar 2009 13:25:37 GMT (605kb)

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

\\

We discuss a problem of a nonadiabatic Bose Josephson junction. We use

non-equilibrium field theoretical methods to account for excitations above the

condensates, which are induced by the nonadibaticity. We show how the coherent

tunneling between the condensates, known from mean-field calculations, gets

drastically modified by the non-equilibrium effects. We also estimate a

time-scale, at which the condensate dynamics switches from slow Josephson

oscillations to fast Rabi oscillations between the descrete quasi-particle

levels. We analyze in detail how this time scale depends on the parameters of

our system.

\\ ( http://arxiv.org/abs/0903.5459 , 605kb)

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arXiv:0903.5190

Date: Mon, 30 Mar 2009 11:42:31 GMT (832kb)

Title: Threshold of a random laser based on Raman gain in cold atoms

Authors: William Guerin (INLN), Nicolas Mercadier (INLN), Davide Brivio (INLN),

Robin Kaiser (INLN)

Categories: physics.optics cond-mat.dis-nn physics.atom-ph

\\

We address the problem of achieving a random laser with a cloud of cold

atoms, in which gain and scattering are provided by the same atoms. In this

system, the elastic scattering cross-section is related to the complex atomic

polarizability. As a consequence, the random laser threshold is expressed as a

function of this polarizability, which can be fully determined by spectroscopic

measurements. We apply this idea to experimentally evaluate the threshold of a

random laser based on Raman gain between non-degenerate Zeeman states and find

a critical optical thickness on the order of 200, which is within reach of

state-of-the-art cold-atom experiments.

\\ ( http://arxiv.org/abs/0903.5190 , 832kb)

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arXiv:0904.0050

Date: Wed, 1 Apr 2009 02:29:36 GMT (29kb,D)

Title: Rigorous Upper Bound on the Critical Temperature of Dilute Bose Gases

Authors: Robert Seiringer, Daniel Ueltschi

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

Comments: 10 pages, 2 figures

\\

We prove exponential decay of the off-diagonal correlation function in the

two-dimensional homogeneous Bose gas when a2 \rho is small and the temperature

T satisfies T > 4 \pi \rho / \ln |\ln(a2\rho). Here, a is the scattering

length of the repulsive interaction potential and \rho is the density. To

leading order in a2 \rho, this bound agrees with the expected critical

temperature for superfluidity. In the three-dimensional Bose gas, exponential

decay is proved when \Delta T_c / T_c0 > 5 \sqrt{a \rho^{1/3}}, where T_c0 is

the critical temperature of the ideal gas. While this condition is not expected

to be sharp, it gives a rigorous upper bound on the critical temperature for

Bose-Einstein condensation.

\\ ( http://arxiv.org/abs/0904.0050 , 29kb)

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arXiv:0904.0053

Date: Wed, 1 Apr 2009 10:18:46 GMT (169kb)

Title: Comparative study of the finite-temperature thermodynamics of a unitary

Fermi gas

Authors: Fang Qin, Ji-sheng Chen

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

Comments: 7 pages; accepted for publication in Phys. Rev. A

\\

We study the finite-temperature thermodynamics of a unitary Fermi gas. The

chemical potential, energy density and entropy are given analytically with the

quasi-linear approximation. The ground state energy agrees with previous

theoretical and experimental results. Recently, the generalized exclusion

statistics is applied to the discussion of the finite-temperature unitary Fermi

gas thermodynamics. A concrete comparison between the two different approaches

is performed. Emphasis is made on the behavior of the entropy per particle. In

physics, the slope of entropy gives the information for the effective fermion

mass $m^*/m$ in the low temperature strong degenerate region. Compared with

$m^*/m \approx 0.70<1$ given in terms of the generalized exclusion statistics,

our quasi-linear approximation determines $m^*/m\approx 1.11>1$.

\\ ( http://arxiv.org/abs/0904.0053 , 169kb)

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arXiv:0904.0086

Date: Wed, 1 Apr 2009 08:16:52 GMT (860kb)

Title: Excited spin states and phase separation in spinor Bose-Einstein

condensates

Authors: Michal Matuszewski, Tristram J. Alexander, Yuri S. Kivshar

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

\\

We analyze the structure of spin-1 Bose-Einstein condensates in the presence

of a homogenous magnetic field. We classify the homogenous stationary states

and study their existence, bifurcations, and energy spectra. We reveal that the

phase separation can occur in the ground state of polar condensates, while the

spin components of the ferromagnetic condensates are always miscible and no

phase separation occurs. Our theoretical model, confirmed by numerical

simulations, explains that this phenomenon takes place when the energy of the

lowest homogenous state is a concave function of the magnetization. In

particular, we predict that phase separation can be observed in a $^{23}$Na

condensate confined in a highly elongated harmonic trap. Finally, we discuss

the phenomena of dynamical instability and spin domain formation.

\\ ( http://arxiv.org/abs/0904.0086 , 860kb)

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arXiv:0904.0155

Date: Wed, 1 Apr 2009 13:24:03 GMT (1778kb)

Title: Effect of interactions on the diffusive expansion of a Bose-Einstein

condensate in a 3D random potential

Authors: N. Cherroret and S. E. Skipetrov

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

Comments: 15 pages, 4 figures

\\

We theoretically study the influence of weak interactions on the diffusive

expansion of a Bose-Einstein condensate in a three-dimensional random

potential. For this purpose we develop a perturbative approach and calculate

analytically the first-order nonlinear correction to the ensemble-averaged

atomic density as a function of position and time. We find that interactions

renormalize the typical diffusion coefficient of the condensate. The magnitude

of the nonlinear correction is controlled by a single dimensionless parameter

that includes both interaction and disorder strengths.

\\ ( http://arxiv.org/abs/0904.0155 , 1778kb)

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arXiv:0807.1945 (*cross-listing*)

Date: Sat, 12 Jul 2008 00:49:29 GMT (485kb,D)

Date (revised v2): Fri, 6 Mar 2009 23:34:41 GMT (459kb,D)

Date (revised v3): Fri, 27 Mar 2009 21:36:45 GMT (459kb,D)

Title: Dynamics of Quantum Vorticity in a Random Potential

Authors: Bennett Link

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

Comments: Physical Review Letters, final version

\\

I study the dynamics of a superfluid vortex in a random potential, as in the

inner crust of a neutron star. Below a critical flow velocity of the ambient

superfluid, a vortex is effectively immobilized by lattice forces even in the

limit of zero dissipation. Low-velocity, translatory motion is not dynamically

possible, a result with important implications for understanding neutron star

precession and the dynamical properties of superfluid nuclear matter.

\\ ( http://arxiv.org/abs/0807.1945 , 459kb)

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arXiv:0904.0115

Date: Wed, 1 Apr 2009 09:59:09 GMT (49kb)

Title: Dynamics of an inhomogeneous quantum phase transition

Authors: Jacek Dziarmaga and Marek M. Rams

Categories: quant-ph

Comments: 4 pages, 3 figures

\\

We argue that in a second order quantum phase transition driven by an

inhomogeneous quench density of quasiparticle excitations is dramatically

suppressed when velocity at which a critical point propagates across a system

falls below a threshold velocity given by a ratio of the Kibble-Zurek

correlation length to the inverse energy gap at freeze-out. We support this

general prediction by an analytic solution in the particular case of the

quantum Ising chain.

\\ ( http://arxiv.org/abs/0904.0115 , 49kb)

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arXiv:0904.0150

Date: Wed, 1 Apr 2009 13:51:58 GMT (12kb)

Title: Hidden symmetry and nonlinear paraxial atom optics

Authors: F. Impens

Categories: quant-ph

Comments: 5 pages. Submitted to Phys. Rev. A

\\

We exploit a hidden symmetry of the nonlinear wave equation to analyse the

propagation of paraxial and uniform atom-laser beams in time-independent,

quadratic and cylindrical potentials varying smoothly along the propagation

axis. The quality factor and the paraxial ABCD formalism are generalized to

account exactly for mean-field interaction effects in such beams.

\\ ( http://arxiv.org/abs/0904.0150 , 12kb)

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arXiv:0904.0234

Date: Wed, 1 Apr 2009 18:25:35 GMT (34kb)

Title: The impact of magnetic properties on atom-wall interaction

Authors: G. Bimonte, G. L. Klimchitskaya, and V. M. Mostepanenko

Categories: quant-ph

Comments: 14 pages, 2 figures; accepted for publication in Phys. Rev. A

\\

The Lifshitz-type formulas for the free energy and Casimir-Polder force

acting between an atom possessing a permanent magnetic moment and a wall made

of different materials are derived. Simple model allowing analytic results is

considered where the atomic magnetic susceptibility is frequency-independent

and wall is made of ideal metal. Numerical computations of the Casimir-Polder

force are performed for H atom interacting with walls made of ideal metal,

nonmagnetic (Au) and ferromagnetic (Fe) metals and of ferromagnetic dielectric.

It is shown that for the first three wall materials the inclusion of the

magnetic moment of an atom decreases and for the fourth material increases the

magnitude of the Casimir-Polder force.

\\ ( http://arxiv.org/abs/0904.0234 , 34kb)

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arXiv:0904.0238

Date: Wed, 1 Apr 2009 19:32:16 GMT (86kb)

Title: Bragg spectroscopy for measuring Casimir-Polder interactions with

Bose-Einstein condensates above corrugated surfaces

Authors: Gustavo A. Moreno, Diego A. R. Dalvit, Esteban Calzetta

Categories: quant-ph

Comments: 4 pages, 3 figures

\\

We propose a method to probe dispersive atom-surface interactions by

measuring via two-photon Bragg spectroscopy the dynamic structure factor of a

Bose-Einstein condensate above corrugated surfaces. We show that this method

enables high resolution measurements of Casimir-Polder forces with present-day

technology.

\\ ( http://arxiv.org/abs/0904.0238 , 86kb)

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arXiv:0904.0225

Date: Wed, 1 Apr 2009 17:24:02 GMT (2968kb)

Title: Demonstrating coherent control in 85Rb2 using ultrafast laser pulses: a

theoretical outline of two experiments

Authors: Hugo E. L. Martay, David J. McCabe, Duncan G. England, Melissa E.

Friedman, Jovana Petrovic, and Ian A. Walmsley

Categories: physics.atom-ph physics.chem-ph

Comments: 8 pages, 9 figures, submitted to PRA

\\

Calculations relating to two experiments that demonstrate coherent control of

preformed rubidium-85 molecules in a magneto-optical trap using ultrafast laser

pulses are presented. In the first experiment, it is shown that pre-associated

molecules in an incoherent mixture of states can be made to oscillate

coherently using a single ultrafast pulse. A novel mechanism that can transfer

molecular population to more deeply bound vibrational levels is used in the

second. Optimal parameters of the control pulse are presented for the

application of the mechanism to molecules in a magneto-optical trap. The

calculations make use of an experimental determination of the initial state of

molecules photoassociated by the trapping lasers in the magneto-optical trap

and use shaped pulses consistent with a standard ultrafast laser system.

\\ ( http://arxiv.org/abs/0904.0225 , 2968kb)

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arXiv:0904.0244 (*cross-listing*)

Date: Wed, 1 Apr 2009 19:23:15 GMT (239kb,D)

Title: A pump-probe study of the photoassociation of rubidium molecules

Authors: David J. McCabe, Duncan G. England, Hugo E. L. Martay, Melissa E.

Friedman, Jovana Petrovic, Emiliya Dimova, B\'eatrice Chatel and Ian A.

Walmsley

Categories: physics.chem-ph physics.atom-ph physics.optics

Comments: 9 pages, 7 figures

\\

An experimental pump-probe study of the excited-state dynamics of ultracold

rubidium molecules is presented together with numerical simulations of the

process. The formation of loosely bound excited-state dimers by

photoassociation is observed as a first step towards a fully coherent pump-dump

approach to the stabilization of Rb$_2$ into its lowest ground vibrational

states. A spectroscopic study of the initial state of the colliding atom pairs

prior to the photoassociation process is performed.

\\ ( http://arxiv.org/abs/0904.0244 , 239kb)

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\\

arXiv:0904.0412

Date: Thu, 2 Apr 2009 16:00:21 GMT (1120kb,D)

Title: Probing interaction-induced ferromagnetism in optical superlattices

Authors: J. von Stecher, E. Demler, M. D. Lukin, A. M. Rey

Categories: cond-mat.quant-gas

Comments: 4+ pages, 4 figures

\\

We propose a controllable method for observing interaction induced

ferromagnetism in ultracold fermionic atoms loaded in optical superlattices. We

first discuss how to probe and control Nagaoka ferromagnetism in an array of

isolated plaquettes (four lattice sites arranged in a square). Next, we show

that introducing a weak interplaquette coupling destroys the ferromagnetic

correlations. To overcome this instability we propose to mediate long-range

ferromagnetic correlations among the plaquettes via double-exchange processes.

Conditions for experimental realization and techniques to detect such states

are discussed.

\\ ( http://arxiv.org/abs/0904.0412 , 1120kb)

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The replacements:

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\\

arXiv:cond-mat/0607433

replaced with revised version Sun, 29 Mar 2009 23:01:20 GMT (175kb,D)

Title: Coherent Collective Excitations in a Superfluid: Spontaneously Broken

Symmetries and Fluctuations-Dissipation

Authors: S.J. Han

Categories: cond-mat.other

Comments: 84 pages, 1 figure, (1) The Bose-Einstein condensation is discussed

in both a degenerate Bose gas and an imperfect Bose gas to show how the

pair-interaction affects the nature of phase-transition, (2) The

Onsager-Feynman quantization of circulation in He II is discussed with the

identifiable cause with Planck's quantum condition

\\ ( http://arxiv.org/abs/cond-mat/0607433 , 175kb)

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\\

arXiv:0811.2030 (*cross-listing*)

replaced with revised version Mon, 30 Mar 2009 07:28:53 GMT (517kb)

Title: A comparative study of dynamical simulation methods for the dissociation

of molecular Bose-Einstein condensates

Authors: S. L. W. Midgley, S. Wuester, M. K. Olsen, M. J. Davis and K. V.

Kheruntsyan

Categories: quant-ph cond-mat.other

Comments: 11 pages, 7 figures, corrected typos, minor content changes

\\ ( http://arxiv.org/abs/0811.2030 , 517kb)

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arXiv:0903.4058

replaced with revised version Sun, 29 Mar 2009 04:10:05 GMT (55kb)

Title: Interaction Effects on Wannier Functions of a Bose-Einstein Condensate

in an Optical Lattice and Implications for Bose-Hubbard Model

Authors: Z. X. Liang, B. B. Hu, and Biao Wu

Categories: cond-mat.str-el

Comments: 4 pages, 3 figures

\\ ( http://arxiv.org/abs/0903.4058 , 55kb)

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\\

arXiv:0902.2058

replaced with revised version Thu, 2 Apr 2009 14:13:42 GMT (2457kb)

Title: Multi-resonant spinor dynamics in a Bose-Einstein condensate

Authors: Carsten Klempt, Oliver Topic, Gebremedhn Gebreyesus, Manuel Scherer,

Thorsten Henninger, Philipp Hyllus, Wolfgang Ertmer, Luis Santos, and Jan

Arlt

Categories: quant-ph cond-mat.other

Comments: 5 pages, 4 figures

\\ ( http://arxiv.org/abs/0902.2058 , 2457kb)

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\\

arXiv:0809.1468

replaced with revised version Tue, 31 Mar 2009 16:07:44 GMT (566kb)

Title: Bose-Einstein condensation in an optical lattice: A perturbation

approach

Authors: C. Trallero-Giner, V. Lopez-Richard, Ming-Chiang Chung, Andreas

Buchleitner

Categories: cond-mat.other

\\ ( http://arxiv.org/abs/0809.1468 , 566kb)

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\\

arXiv:0902.4119

replaced with revised version Tue, 31 Mar 2009 10:54:09 GMT (34kb)

Title: Multiple condensed phases in attractively interacting Bose systems

Authors: M. M\"annel, K. Morawetz, P. Lipavsk\'y

Categories: cond-mat.stat-mech nucl-th

\\ ( http://arxiv.org/abs/0902.4119 , 34kb)

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\\

arXiv:0807.2002

replaced with revised version Wed, 1 Apr 2009 19:50:15 GMT (162kb)

Title: Effective one-dimensional dynamics of elongated Bose-Einstein

condensates

Authors: A. Mu\~noz Mateo and V. Delgado (Univ. La Laguna)

Categories: cond-mat.other

Comments: Final version published in Annals of Physics; 10 pages, 5 figures

Journal-ref: Annals of Physics 324, 709 (2009)

DOI: 10.1016/j.aop.2008.10.002

\\ ( http://arxiv.org/abs/0807.2002 , 162kb)

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\\

arXiv:0809.3239

replaced with revised version Wed, 1 Apr 2009 18:38:52 GMT (28kb)

Title: Discerning Incompressible and Compressible Phases of Cold Atoms in

Optical Lattices

Authors: V.W. Scarola, L. Pollet, J. Oitmaa, M. Troyer

Categories: cond-mat.other quant-ph

Journal-ref: Phys. Rev. Lett. 102, 135302 (2009)

\\ ( http://arxiv.org/abs/0809.3239 , 28kb)

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\\

arXiv:0903.4858

replaced with revised version Wed, 1 Apr 2009 06:59:43 GMT (452kb)

Title: Feshbach Resonances and Medium Effects in ultracold atomic Gases

Authors: G. M. Bruun

Categories: cond-mat.other

Comments: Presented at the 5th workshop on Critical Stability, Erice, Italy

13-17 October 2008. 8 pages, 3 figures. Figure caption corrected

DOI: 10.1007/s00601-009-0040-9

\\ ( http://arxiv.org/abs/0903.4858 , 452kb)

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\\

arXiv:0903.4549

replaced with revised version Wed, 1 Apr 2009 15:38:33 GMT (871kb)

Title: Photoassociation and coherent transient dynamics in the interaction of

ultracold rubidium atoms with shaped femtosecond pulses - I. Experiment

Authors: Wenzel Salzmann, Terry Mullins, Simone G\"otz, Magnus Albert, Judith

Eng, Roland Wester, and Matthias Weidem\"uller, Fabian Weise, Andrea Merli,

Stefan M. Weber, Franziska Sauer, Ludger W\"oste, and Albrecht Lindinger

Categories: physics.atom-ph physics.chem-ph

\\ ( http://arxiv.org/abs/0903.4549 , 871kb)

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\\

arXiv:0806.0814

replaced with revised version Thu, 2 Apr 2009 14:50:13 GMT (617kb)

Title: Observation of vortex formation in an oscillating trapped Bose-Einstein

condensate

Authors: E. A. L. Henn, J. A. Seman, E. R. F. Ramos, M. Caracanhas, P.

Castilho, E. P. Olimpio, G. Roati, D. V. Magalh\~aes, K. M. F. Magalh\~aes,

V.S. Bagnato

Categories: cond-mat.other cond-mat.mes-hall

Comments: 1 figure added, text modified, accepted for publication Phys. Rev. A

\\ ( http://arxiv.org/abs/0806.0814 , 617kb)

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\\

arXiv:0806.1773

replaced with revised version Thu, 2 Apr 2009 09:50:49 GMT (60kb)

Title: Exact solution for infinitely strongly interacting Fermi gases in tight

waveguides

Authors: Liming Guan, Shu Chen, Yupeng Wang, Zhong-Qi Ma

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

Comments: 4 pages, 3 figures, version accepted for publication in Phys. Rev.

Lett

\\ ( http://arxiv.org/abs/0806.1773 , 60kb)

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\\

arXiv:0902.2058

replaced with revised version Thu, 2 Apr 2009 14:13:42 GMT (2457kb)

Title: Multi-resonant spinor dynamics in a Bose-Einstein condensate

Authors: Carsten Klempt, Oliver Topic, Gebremedhn Gebreyesus, Manuel Scherer,

Thorsten Henninger, Philipp Hyllus, Wolfgang Ertmer, Luis Santos, and Jan

Arlt

Categories: quant-ph cond-mat.other

Comments: 5 pages, 4 figures

\\ ( http://arxiv.org/abs/0902.2058 , 2457kb)

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\\

arXiv:0903.5343

replaced with revised version Thu, 2 Apr 2009 16:07:24 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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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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