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

Date: Tue, 29 Jan 2008 20:25:26 +1000

Date: Tue, 29 Jan 2008 20:25:26 +1000

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

It has been a couple of busy weeks... 33 new preprints and 10 replacements this

week:

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arXiv:0801.2795

Date: Thu, 17 Jan 2008 23:43:20 GMT (26kb)

Title: Bose-Einstein condensation in magnetic systems under strong fields

Authors: D. Reyes, M. A. Continentino and A. Paduan-Filho

Categories: cond-mat.str-el

Comments: 4 pages, 1 figure. submitted to PRB

\\

At zero temperature and strong applied magnetic fields the ground sate of an

anisotropic antiferromagnet is a saturated paramagnet with fully aligned spins.

We study the quantum phase transition as the field is reduced below an upper

critical $H_{c2}$ and the system enters a XY-antiferromagnetic phase. Using a

bond operator representation we consider a model spin-1 Heisenberg

antiferromagnetic with single-ion anisotropy in hyper-cubic lattices under

strong magnetic fields. We show that the transition at $H_{c2}$ can be

interpreted as a Bose-Einstein condensation (BEC) of magnons. The theoretical

results are used to analyze our magnetization versus field data in the organic

compound $NiCl_2$-$4SC(NH_2)_2$ (DTN) at very low temperatures. This is the

ideal BEC system to study this transition since $H_{c2}$ is sufficiently low to

be reached with static magnetic fields (as opposed to pulsed fields). The

scaling of the magnetization as a function of field and temperature close to

$H_{c2}$ shows excellent agreement with the theoretical predictions. It allows

to obtain the quantum critical exponents and confirm the BEC nature of the

transition at $H_{c2}$.

\\ ( http://arxiv.org/abs/0801.2795 , 26kb)

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arXiv:0801.2798

Date: Fri, 18 Jan 2008 00:41:04 GMT (38kb)

Title: Heteronuclear fermionic superfluids with spin degrees of freedom

Authors: D. B. M. Dickerscheid, Y. Kawaguchi, M. Ueda

Categories: cond-mat.stat-mech

Comments: Submitted for publication in PRA

\\

We present a theory of spinor superfluidity in a two-species heteronuclear

ultracold fermionic atomic gas consisting of arbitrary half-integer spin and

one-half spin atoms. In particular, we focus on the magnetism of the superfluid

phase and determine the possible phases in the absence of a magnetic field. Our

work demonstrates similarities between heteronuclear fermionic superfluids and

spinor Bose-Einstein condensates at the mean-field level. Possible experimental

situations are discussed.

\\ ( http://arxiv.org/abs/0801.2798 , 38kb)

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arXiv:0801.2872

Date: Fri, 18 Jan 2008 12:28:40 GMT (289kb)

Title: Characterization of reconnecting vortices in superfluid helium

Authors: Gregory P. Bewley, Matthew S. Paoletti, Katepalli R. Sreenivasan, and

Daniel P. Lathrop

Categories: cond-mat.other cond-mat.supr-con

\\

When two vortices cross, each of them breaks into two parts and exchanges

part of itself for part of the other. This process, called vortex reconnection,

occurs in classical as well as superfluids, and in magnetized plasmas and

superconductors. We present the first experimental observations of reconnection

between quantized vortices in superfluid helium. We do so by imaging

micron-sized solid hydrogen particles trapped on quantized vortex cores (Bewley

GP, Lathrop DP, Sreenivasan KR, 2006, Nature, 441:588), and by inferring the

occurrence of reconnection from the motions of groups of recoiling particles.

We show the distance separating particles on the just-reconnected vortex lines

grows as a power law in time. The average value of the scaling exponent is

approximately 1/2, consistent with the scale-invariant evolution of the

vortices.

\\ ( http://arxiv.org/abs/0801.2872 , 289kb)

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arXiv:0801.2910

Date: Fri, 18 Jan 2008 15:34:23 GMT (151kb)

Title: Functional renormalization for Bose-Einstein Condensation

Authors: S. Floerchinger and C. Wetterich

Categories: cond-mat.supr-con

Comments: 21 pages, 16 figures

\\

We investigate Bose-Einstein condensation for interacting bosons at zero and

nonzero temperature. Functional renormalization provides us with a consistent

method to compute the effect of fluctuations beyond the Bogoliubov

approximation. For three dimensional dilute gases, we find an upper bound on

the scattering length a which is of the order of the microphysical scale -

typically the range of the Van der Waals interaction. In contrast to fermions

near the unitary bound, no strong interactions occur for bosons with

approximately pointlike interactions, thus explaining the high quantitative

reliability of perturbation theory for most quantities. For zero temperature we

compute the quantum phase diagram for bosonic quasiparticles with a general

dispersion relation, corresponding to an inverse microphysical propagator with

terms linear and quadratic in the frequency. We compute the temperature

dependence of the condensate and particle density n, and find for the critical

temperature T_c a deviation from the free theory, Delta T_c/T_c = 2.1 a

n^{1/3}. For the sound velocity at zero temperature we find very good agreement

with the Bogoliubov result, such that it may be used to determine the particle

density accurately.

\\ ( http://arxiv.org/abs/0801.2910 , 151kb)

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arXiv:0801.2928

Date: Fri, 18 Jan 2008 16:26:16 GMT (453kb)

Title: Cold atom dynamics in non-Abelian gauge fields

Authors: A. Jacob, P. Ohberg, G. Juzeliunas and L. Santos

Categories: cond-mat.other

Comments: 8 pages, 9 figures

Journal-ref: Appl. Phys. B 89, 439-445 (2007)

\\

The dynamics of ultracold neutral atoms subject to a non-Abelian gauge field

is investigated. In particular we analyze in detail a simple experimental

scheme to achieve a constant, but non-Abelian gauge field, and discuss in the

frame of this gauge field the non-Abelian Aharanov-Bohm effect. In the last

part of this paper, we discuss intrinsic non-Abelian effects in the dynamics of

cold atomic wavepackets.

\\ ( http://arxiv.org/abs/0801.2928 , 453kb)

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arXiv:0801.2935

Date: Fri, 18 Jan 2008 16:45:35 GMT (153kb)

Title: Landau levels of cold atoms in non-Abelian gauge fields

Authors: A. Jacob, P. Ohberg, G. Juzeliunas and L. Santos

Categories: cond-mat.other

Comments: 13 pages, 9 figures

\\

The Landau levels of cold atomic gases in non-Abelian gauge fields are

analyzed. In particular we identify effects on the energy spectrum and density

distribution which are purely due to the non-Abelian character of the fields.

We investigate in detail non-Abelian generalizations of both the Landau and the

symmetric gauge. Finally, we discuss how these non-Abelian Landau and symmetric

gauges may be generated by means of realistically feasible lasers in a tripod

scheme.

\\ ( http://arxiv.org/abs/0801.2935 , 153kb)

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arXiv:0801.2952

Date: Fri, 18 Jan 2008 18:33:23 GMT (964kb)

Title: Rotating trapped Bose-Einstein condensates

Authors: Alexander L. Fetter

Categories: cond-mat.stat-mech

Comments: 44 pages, 18 figures, submitted to Reviews of Modern Physics

\\

After reviewing the ideal Bose-Einstein gas in a box and in a harmonic trap,

I discuss the effect of interactions on the formation of a Bose-Einstein

condensate (BEC), along with the dynamics of small-amplitude perturbations (the

Bogoliubov equations). When the condensate rotates with angular velocity Omega,

one or several vortices nucleate, with many observable consequences. With more

rapid rotation, the vortices form a dense triangular array, and the collective

behavior of these vortices has additional experimental implications. For Omega

near the radial trap frequency omega_perp, the lowest-Landau-level

approximation becomes applicable, providing a simple picture of such rapidly

rotating condensates. Eventually, as Omega approaches omega_perp, the rotating

dilute gas is expected to undergo a quantum phase transition from a superfluid

to various highly correlated (nonsuperfluid) states analogous to those familiar

from the fractional quantum Hall effect for electrons in a strong perpendicular

magnetic field.

\\ ( http://arxiv.org/abs/0801.2952 , 964kb)

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arXiv:0801.2964

Date: Thu, 17 Jan 2008 22:31:18 GMT (430kb)

Title: Vortex Splitting in Subcritical Nonlinear Schrodinger Equation

Authors: Natalia G. Berloff

Categories: cond-mat.other physics.flu-dyn

Comments: Invited submission to the special issue on Vortex Rings, Journal of

Fluid Dynamics Research

\\

Vortices and axisymmetric vortex rings are considered in the framework of the

subcritical nonlinear Schrodinger equations. The higher order nonlinearity

present in such systems models many-body interactions in superfluid systems and

allows one to study the effects of negative pressure on vortex dynamics. We

find the critical pressure for which the straight-line vortex becomes unstable

to radial expansion of the core. The energy of the straight-line vortices and

energy, impulse and velocity of vortex rings are calculated. The effect of a

varying pressure on the vortex core is studied. It is shown that under the

action of the periodically varying pressure field a vortex ring may split into

many vortex rings and the conditions for which this happens are elucidated.

These processes are also relevant to experiments in Bose-Einstein condensates

where the strength and the sign of two-body interactions can be changed via

Feshbach resonance.

\\ ( http://arxiv.org/abs/0801.2964 , 430kb)

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arXiv:0801.2791

Date: Thu, 17 Jan 2008 23:18:13 GMT (277kb)

Title: Versatile two-dimensional potentials for ultra-cold atoms

Authors: S.K. Schnelle, E.D. van Ooijen, M.J. Davis, N.R. Heckenberg and H.

Rubinsztein-Dunlop

Categories: physics.atom-ph

Comments: 8 pages, 5 figures

\\

We propose and investigate a technique for generating smooth two-dimensional

potentials for ultra-cold atoms based on the rapid scanning of a far-detuned

laser beam using a two-dimensional acousto-optical modulator (AOM). We

demonstrate the implementation of a feed-forward mechanism for fast and

accurate control of the spatial intensity of the laser beam, resulting in

improved homogeneity for the atom trap. This technique could be used to

generate a smooth toroidal trap that would be useful for static and dynamic

experiments on superfluidity and persistent currents with ultra-cold atoms.

\\ ( http://arxiv.org/abs/0801.2791 , 277kb)

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arXiv:0801.2943

Date: Fri, 18 Jan 2008 17:26:10 GMT (962kb,D)

Title: Trapping molecules on a chip in traveling potential wells

Authors: Samuel A. Meek, Hendrick L. Bethlem, Horst Conrad, Gerard Meijer

Categories: physics.atom-ph

Comments: 4 pages, 3 figures

\\

A microstructured array of over 1200 electrodes on a substrate has been

configured to generate an array of local minima of electric field strength with

a periodicity of $120 \mu$m about $25 \mu$m above the substrate. By applying

sinusoidally varying potentials to the electrodes, these minima can be made to

move smoothly along the array. Polar molecules in low field seeking quantum

states can be trapped in these traveling potential wells. This is

experimentally demonstrated by transporting metastable CO molecules in 30 mK

deep wells that move at constant velocities above the substrate.

\\ ( http://arxiv.org/abs/0801.2943 , 962kb)

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arXiv:0801.3127

Date: Mon, 21 Jan 2008 05:37:43 GMT (16kb)

Title: Phase Diagram of Cold Polarized Fermi Gas in Two Dimensions

Authors: Lianyi He and Pengfei Zhuang

Categories: cond-mat.supr-con

Comments: 4 pages, 1 figure

\\

The superfluid phase diagrams and bound states in a two-dimensional cold

polarized Fermi gas are systematically and analytically studied. Phase

separation is the energetically favored ground state at finite polarization for

all coupling, and there is no stable gapless phase at strong coupling. Phase

separation appears explicitly in both coupling-Zeeman field and

coupling-polarization planes, and there exist a lower and an upper critical

Zeeman field, in contrast to the well-known result in the weak coupling limit.

The di-fermion bound states can survive in highly polarized normal state even

at weak coupling limit.

\\ ( http://arxiv.org/abs/0801.3127 , 16kb)

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arXiv:0801.3137

Date: Mon, 21 Jan 2008 07:10:52 GMT (11kb)

Title: Analysis on Condition for Emergence of Complex Eigenvalues in the

Bogoliubov-de Gennes Equations

Authors: Y.Nakamura, M.Mine, M.Okumura, and Y.Yamanaka

Categories: cond-mat.other

Comments: 6pages

\\

The condition for the appearance of dynamical instability of the

Bose-condensed system, characterized by the emergence of complex eigenvalues in

the Bogoliubov-de Gennes equations, is studied analytically. We perturbatively

expand both the Gross-Pitaevskii and Bogoliubov-de Gennes equations with

respect to the coupling constant. It is concluded that the degeneracy between a

positive-norm eigenmode and a negative-norm one is essential for the emergence

of complex modes. Based on the conclusion, we justify the two-mode

approximation applied in our previous work [E. Fukuyama \textit{et al}., Phys.

Rev. A {\bf 76}, 043608 (2007)], in which we analytically studied the condition

for the existence of complex modes when the condensate has a highly quantized

vortex.

\\ ( http://arxiv.org/abs/0801.3137 , 11kb)

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arXiv:0801.3154

Date: Mon, 21 Jan 2008 16:53:52 GMT (357kb)

Title: Number squeezing, quantum fluctuations and oscillations in mesoscopic

Bose Josephson junctions

Authors: G. Ferrini, A. Minguzzi, F.W.J. Hekking (UJF-CNRS Grenoble)

Categories: cond-mat.mes-hall

Comments: 4 pages, 3 figures

\\

Starting from a quantum two-mode Bose-Hubbard Hamiltonian we determine the

ground state properties, momentum distribution and dynamical evolution for a

Bose Josephson junction realized by an ultracold Bose gas in a double-well

trap. Varying the well asymmetry we identify Mott-like regions of parameters

where number fluctuations are suppressed and the interference fringes in the

momentum distribution are strongly reduced. We also show how Schroedinger cat

states, realized from an initially phase coherent state by a sudden rise of the

barrier among the two wells, will give rise to a destructive interference in

the time-dependent momentum distribution.

\\ ( http://arxiv.org/abs/0801.3154 , 357kb)

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arXiv:0801.3168

Date: Mon, 21 Jan 2008 10:45:13 GMT (32kb)

Title: Representative statistical ensembles for Bose systems with broken gauge

symmetry

Authors: V.I. Yukalov

Categories: cond-mat.stat-mech

Comments: 43 pages, Latex file

Journal-ref: Ann. Phys. 323 (2008) 461-499

\\

Bose-condensed systems with broken global gauge symmetry are considered. The

description of these systems, as has been shown by Hohenberg and Martin,

possesses an internal inconsistency, resulting in either nonconserving theories

or yielding an unphysical gap in the spectrum. The general notion of

representative statistical ensembles is formulated for arbitrary statistical

systems, equilibrium or not. The principal idea of this notion is the necessity

of taking into account all imposed conditions that uniquely define the given

statistical system. Employing such a representative ensemble for Bose-condensed

systems removes all paradoxes, yielding a completely self-consistent theory,

both conserving and gapless in any approximation. This is illustrated for an

equilibrium uniform Bose system.

\\ ( http://arxiv.org/abs/0801.3168 , 32kb)

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arXiv:0801.3252

Date: Mon, 21 Jan 2008 19:42:02 GMT (313kb)

Title: Adiabatic melting of two-component Mott-insulator states

Authors: M. Rodriguez, S. R. Clark and D. Jaksch

Categories: cond-mat.mes-hall

Comments: 10 pages, 9 figures

\\

We analyze the outcome of a Mott insulator to superfluid transition for a

two-component Bose gas with two atoms per site in an optical lattice in the

limit of slow ramping down the lattice potential. This manipulation of the

initial Mott insulating state transforms local correlations between hyperfine

states of atom pairs into multiparticle correlations extending over the whole

system. We show how to create macroscopic twin Fock states in this way an that,

in general, the obtained superfluid states are highly depleted even for initial

ground Mott insulator states.

\\ ( http://arxiv.org/abs/0801.3252 , 313kb)

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arXiv:0801.3158

Date: Mon, 21 Jan 2008 10:15:26 GMT (157kb)

Title: Precision measurements with polar molecules: the role of the black body

radiation

Authors: Nicolas Vanhaecke (LAC), Olivier Dulieu (LAC)

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

Proxy: ccsd hal-00208102

Journal-ref: Molecular Physics 105, 11-12 (2007) 1723-1731

DOI: 10.1080/00268970701466261

\\

In the perspective of the outstanding developments of high-precision

measurements of fundamental constants using polar molecules related to ultimate

checks of fundamental theories, we investigate the possibly counterproductive

role of black-body radiation on a series of diatomic molecules which would be

trapped and observed for long durations. We show that the absorption of

black-body radiation at room temperature may indeed limit the lifetime of

trapped molecules prepared in a well-defined quantum state. Several examples

are treated, corresponding to pure rotational absorption, pure vibrational

absorption or both. We also investigate the role of a black-body

radiation-induced energy shift on molecular levels and how it could affect

high-precision frequency measurements.

\\ ( http://arxiv.org/abs/0801.3158 , 157kb)

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arXiv:0801.3255

Date: Mon, 21 Jan 2008 20:18:44 GMT (181kb,D)

Title: A simple integrated single-atom detector

Authors: Marco Wilzbach, Dennis Heine, S\"onke Groth, Xiyuan Liu, Bj\"orn

Hessmo, J\"org Schmiedmayer

Categories: physics.atom-ph physics.optics

Comments: 4 pages, 3 figures

\\

We experimentally implement an integrated detector capable to detect single

atoms with an efficiency of 56% and a signal-to-noise ratio of 275. We

magnetically guide cold atoms through the focus of a tapered lensed fiber,

mounted on the surface of an atom chip, where they are optically excited and

emit bursts of fluorescent photons. Some of these photons are collected by

another chip-mounted fiber and counted by a photon counter. Simple improvements

will allow atom counting with close to unit efficiency.

\\ ( http://arxiv.org/abs/0801.3255 , 181kb)

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arXiv:0801.3307

Date: Tue, 22 Jan 2008 05:15:06 GMT (190kb)

Title: Solitons in two-dimensional Bose-Einstein condensates

Authors: Shunji Tsuchiya, Franco Dalfovo, Lev P. Pitaevskii

Categories: cond-mat.supr-con cond-mat.other

Comments: 4 pages, 4 figures

\\

The excitations of a two-dimensional (2D) Bose-Einstein condensate in the

presence of a soliton are studied by solving the Kadomtsev-Petviashvili

equation which is valid when the velocity of the soliton approaches the speed

of sound. The excitation spectrum is found to contain states which are

localized near the soliton and have a dispersion law similar to the one of the

stable branch of transverse oscillations of a 1D gray soliton in a 2D

condensate. By using the stabilization method we show that these localized

excitations behave as resonant states coupled to the continuum of free

excitations of the condensate.

\\ ( http://arxiv.org/abs/0801.3307 , 190kb)

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arXiv:0801.3424

Date: Tue, 22 Jan 2008 17:27:14 GMT (89kb)

Title: Critical temperature of interacting Bose gases in two and three

dimensions

Authors: S. Pilati, S. Giorgini, N. Prokof'ev

Categories: cond-mat.other

Comments: 4 pages, 5 figures

\\

We calculate the superfluid transition temperature of homogeneous interacting

Bose gases in three and two spatial dimensions using large-scale Path Integral

Monte Carlo simulations (with up to $N=105$ particles). In 3D we investigate

the limits of the universal critical behavior in terms of the scattering length

alone by using different models for the interatomic potential. We find that

this type of universality sets in at small values of the gas parameter $na3

\lesssim 10^{-4}$. This value is different from the estimate $na3 \lesssim

10^{-6}$ for the validity of the asymptotic expansion in the limit of vanishing

$na3$. In 2D we study the Berezinskii-Kosterlitz-Thouless transition of a gas

with hard-core interactions. For this system we find good agreement with the

classical lattice $|\psi|^4$ model up to very large densities. We also explain

the origin of the existing discrepancy between previous studies of the same

problem.

\\ ( http://arxiv.org/abs/0801.3424 , 89kb)

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arXiv:0801.3428

Date: Tue, 22 Jan 2008 17:49:28 GMT (476kb)

Title: Nonlinear dynamics of Bose-condensed gases by means of a low- to

high-density variational approach

Authors: Alexandru I. Nicolin and R. Carretero-Gonzalez

Categories: cond-mat.other

Comments: 11 pages, 12 figures, submitted to Phys. Rev. A, January 2008

\\

We propose a versatile variational method to investigate the spatio-temporal

dynamics of one-dimensional magnetically-trapped Bose-condensed gases. To this

end we employ a \emph{q}-Gaussian trial wave-function that interpolates between

the low- and the high-density limit of the ground state of a Bose-condensed

gas. Our main result consists of reducing the Gross-Pitaevskii equation, a

nonlinear partial differential equation describing the T=0 dynamics of the

condensate, to a set of only three equations: \emph{two coupled nonlinear

ordinary differential equations} describing the phase and the curvature of the

wave-function and \emph{a separate algebraic equation} yielding the generalized

width. Our equations recover those of the usual Gaussian variational approach

(in the low-density regime), and the hydrodynamic equations that describe the

high-density regime. Finally, we show a detailed comparison between the

numerical results of our equations and those of the original Gross-Pitaevskii

equation.

\\ ( http://arxiv.org/abs/0801.3428 , 476kb)

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arXiv:0801.3437

Date: Tue, 22 Jan 2008 18:35:15 GMT (398kb)

Title: Damped Bloch Oscillations of Bose-Einstein Condensates in Disordered

Potential Gradients

Authors: S. Drenkelforth, G. Kleine B\"uning, J. Will, T. Schulte, N. Murray,

W. Ertmer, L. Santos, and J.J. Arlt

Categories: cond-mat.other

Comments: 13 pages, 9 figures

\\

We investigate both experimentally and theoretically disorder induced damping

of Bloch oscillations of Bose-Einstein condensates in optical lattices. The

spatially inhomogeneous force responsible for the damping is realised by a

combination of a disordered optical and a magnetic gradient potential. We show

that the inhomogeneity of this force results in a broadening of the

quasimomentum spectrum, which in turn causes damping of the centre-of-mass

oscillation. We quantitatively compare the obtained damping rates to the

simulations using the Gross-Pitaevskii equation. Our results are relevant for

high precision experiments on very small forces, which require the observation

of a large number of oscillation cycles.

\\ ( http://arxiv.org/abs/0801.3437 , 398kb)

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arXiv:0801.3320

Date: Tue, 22 Jan 2008 08:01:11 GMT (10kb)

Title: Noise induced current in a double-well trap

Authors: S. Anderloni, F. Benatti and R. Floreanini

Categories: quant-ph

Comments: 10 pages, LaTeX

\\

We study the behavior of cold atoms trapped in optical double well potentials

in presence of noise, either generated by an external environment or by the

trap itself. We show that quite in general the noise can induce a current

between the two wells even when tunneling between the two wells is highly

suppressed (Mott insulator phase). An engineered environment could provide a

test ground for the behavior of such a current.

\\ ( http://arxiv.org/abs/0801.3320 , 10kb)

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arXiv:0801.3351

Date: Tue, 22 Jan 2008 11:48:15 GMT (493kb,D)

Title: Multi-layer atom chips for versatile atom micro manipulation

Authors: Martin Trinker, S\"onke Groth, Stefan Haslinger, Stephanie Manz,

Thomas Betz, Israel Bar-Joseph, Thorsten Schumm, J\"org Schmiedmayer

Categories: physics.atom-ph physics.ins-det

Comments: 4 pages, 5 figures

\\

We employ a combination of optical UV- and electron-beam-lithography to

create an atom chip combining sub-micron wire structures with larger

conventional wires on a single substrate. The new multi-layer fabrication

enables crossed wire configurations, greatly enhancing the flexibility in

designing potentials for ultra cold quantum gases and Bose-Einstein

condensates. Large current densities of >6 x 107 A/cm2 and high voltages of

up to 65 V across 0.3 micron gaps are supported by even the smallest wire

structures. We experimentally demonstrate the flexibility of the next

generation atom chip by producing Bose-Einstein condensates in magnetic traps

created by a combination of wires involving all different fabrication methods

and structure sizes.

\\ ( http://arxiv.org/abs/0801.3351 , 493kb)

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arXiv:0801.3362

Date: Tue, 22 Jan 2008 13:37:14 GMT (989kb,D)

Title: AC electric trapping of neutral atoms

Authors: Sophie Schlunk, Adela Marian, Wieland Schoellkopf, Gerard Meijer

Categories: physics.atom-ph

Comments: 10 pages, 13 figures

\\

We study the dynamic behavior of ultracold neutral atoms in a macroscopic ac

electric trap. Confinement in such a trap is achieved by switching between two

saddle-point configurations of the electric field. The gradual formation of a

stably trapped cloud is observed and the trap performance is studied versus

switching frequency and asymmetry of the switching cycle. Additionally, the

electric field in the trap is mapped out by imaging the atom cloud while the

fields are still on. Finally, the phase space acceptance of the trap is probed

by introducing a modified switching cycle. The experimental results are

reproduced using full three-dimensional trajectory calculations.

\\ ( http://arxiv.org/abs/0801.3362 , 989kb)

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arXiv:0801.3465

Date: Tue, 22 Jan 2008 21:44:51 GMT (50kb)

Title: Mixtures of strongly interacting ultracold bosonic atoms in optical

lattices

Authors: P. Buonsante, S.M. Giamapaolo, F. Illuminati, V. Penna and A. Vezzani

Categories: cond-mat.other

Comments: 5 pages, 3 figures

\\

We investigate the properties of a strongly interacting heteronuclear

boson-boson mixture loaded in a realistic optical lattice. In particular, we

numerically reproduce the apparently surprising results of a recent experiment,

providing a simple explanation. Also, we consider the quantum emulsion states

recently studied on ideal homogeneous systems, and discuss their robustness to

the inhomogeneity introduced by the harmonic trapping typical of standard

experimental realizations.

\\ ( http://arxiv.org/abs/0801.3465 , 50kb)

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arXiv:0801.3571

Date: Wed, 23 Jan 2008 13:17:27 GMT (139kb)

Title: Lowest Landau Level vortex structure of a Bose-Einstein condensate

rotating in a harmonic plus quartic trap

Authors: X. Blanc, N. Rougerie

Categories: cond-mat.stat-mech

Comments: 8 pages, 4 figures

\\

We investigate the vortex patterns appearing in a two-dimensional annular

Bose-Einstein condensate rotating in a quadratic plus quartic confining

potential. We show that in the limit of small anharmonicity the

Gross-Pitaevskii energy can be minimized amongst the Lowest Landau Level wave

functions and use this particular form to get theoretical results in the spirit

of [A. Aftalion X. Blanc F. Nier, Phys. Rev. A 73, 011601(R) (2006)]. In

particular, we show that the vortex pattern is infinite but not uniform. We

also compute numerically the complete vortex structure: it is an Abrikosov

lattice strongly distorted near the edges of the condensate with multiply

quantized vortices appearing at the center of the trap.

\\ ( http://arxiv.org/abs/0801.3571 , 139kb)

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arXiv:0801.3631

Date: Wed, 23 Jan 2008 17:46:26 GMT (126kb)

Title: Anderson localization of a Bose-Einstein condensate in a 3D random

potential

Authors: S.E. Skipetrov, A. Minguzzi, B.A. van Tiggelen, B. Shapiro

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

Comments: 4 pages, 2 figures

\\

We study the effect of Anderson localization on the expansion of a

Bose-Einstein condensate, released from a harmonic trap, in a 3D random

potential. We use scaling arguments and the self-consistent theory of

localization to show that the long-time behavior of the condensate density is

controlled by a single parameter equal to the ratio of the mobility edge and

the chemical potential of the condensate. We find that the two critical

exponents of the localization transition determine the evolution of the

condensate density in time and space.

\\ ( http://arxiv.org/abs/0801.3631 , 126kb)

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arXiv:0801.3398 (*cross-listing*)

Date: Tue, 22 Jan 2008 17:01:19 GMT (54kb)

Title: Stability analysis of $\pi$-kinks in a 0-$\pi$ Josephson junction

Authors: G. Derks, A. Doelman, S.A. van Gils, H. Susanto

Categories: nlin.PS cond-mat.supr-con

Comments: figures are not included due to file size limit

Journal-ref: SIAM J. Appl. Dyn. Syst. 6, 99-141 (2007)

\\

We consider a spatially non-autonomous discrete sine-Gordon equation with

constant forcing and its continuum limit(s) to model a 0-$\pi$ Josephson

junction with an applied bias current. The continuum limits correspond to the

strong coupling limit of the discrete system. The non-autonomous character is

due to the presence of a discontinuity point, namely a jump of $\pi$ in the

sine-Gordon phase. The continuum models admits static solitary waves which are

called $\pi$-kinks and are attached to the discontinuity point. For small

forcing, there are three types of $\pi$-kinks. We show that one of the kinks is

stable and the others are unstable. There is a critical value of the forcing

beyond all static $\pi$-kinks fail to exist. Up to this value, the

(in)stability of the $\pi$-kinks can be established analytically in the strong

coupling limits. Applying a forcing above the critical value causes the

nucleation of $2\pi$-kinks and -antikinks. Besides a $\pi$-kink, the unforced

system also admits a static $3\pi$-kink. This state is unstable in the

continuum models. By combining analytical and numerical methods in the discrete

model, it is shown that the stable $\pi$-kink remains stable, and that the

unstable $\pi$-kinks cannot be stabilized by decreasing the coupling. The

$3\pi$-kink does become stable in the discrete model when the coupling is

sufficiently weak.

\\ ( http://arxiv.org/abs/0801.3398 , 54kb)

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\\

arXiv:0801.3538

Date: Wed, 23 Jan 2008 09:54:35 GMT (183kb,D)

Title: Bose-Einstein condensation on a superconducting atom chip

Authors: C. Roux, A. Emmert, A. Lupascu, T.Nirrengarten, G. Nogues, M. Brune,

J.-M. Raimond and S. Haroche

Categories: physics.atom-ph

Comments: 4 pages, 4 figures. Accepted for publication in Europhysics Letters

\\

We have produced a Bose-Einstein condensate (BEC) on an atom chip using only

superconducting wires in a cryogenic environment. We observe the onset of

condensation for 104 atoms at a temperature of 100 nK. This result opens the

way for studies of atom losses and decoherence in a BEC interacting with a

superconducting surface. Studies of dipole-blockade with long-lived Rydberg

atoms in a small and dense atomic sample are underway.

\\ ( http://arxiv.org/abs/0801.3538 , 183kb)

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\\

arXiv:0801.3688

Date: Thu, 24 Jan 2008 15:15:03 GMT (110kb)

Title: One-Dimensional Bose Gases with N-Body Attractive Interactions

Authors: E. Fersino, G. Mussardo, and A. Trombettoni

Categories: cond-mat.stat-mech

Comments: 12 pages, 8 Postscript figures

\\

We study the ground state properties of a one-dimensional Bose gas with

N-body attractive contact interactions. By using the explicit form of the

bright soliton solution of a generalized nonlinear Schroedinger equation, we

compute the chemical potential and the ground state energy. For N=3, a

localized soliton wave-function exists only for a critical value of the

interaction strength: in this case the ground state has an infinite degeneracy

that can be parameterized by the chemical potential. The stabilization of the

bright soliton solution by an external harmonic trap is also discussed, and a

comparison with the effect of N-body attractive contact interactions in higher

dimensions is presented.

\\ ( http://arxiv.org/abs/0801.3688 , 110kb)

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\\

arXiv:0801.3694

Date: Thu, 24 Jan 2008 01:19:42 GMT (84kb)

Title: How to make a bilayer exciton condensate flow

Authors: Jung-Jung Su and A.H. MacDonald

Categories: cond-mat.mes-hall cond-mat.supr-con

Comments: 10 pages, 3 figures

\\

Bose condensation is responsible for many of the most spectacular effects in

physics because it can promote quantum behavior from the microscopic to the

macroscopic world. Bose condensates can be distinguished by the condensing

object; electron-electron Cooper-pairs are responsible for superconductivity,

Helium atoms for superfluidity, and ultracold alkali atoms in vapors for

coherent matter waves. Electron-hole pair (exciton) condensation has maintained

special interest because it has been difficult to realize experimentally, and

because exciton phase coherence is never perfectly spontaneous. Although ideal

condensates can support an exciton supercurrent, it has not been clear how such

a current could be induced or detected, or how its experimental manifestation

would be altered by the phase-fixing exciton creation and annhilation processes

which are inevitably present. In this article we explain how to induce an

exciton supercurrent in separately contacted bilayer condensates, and predict

electrical effects which enable unambiguous detection.

\\ ( http://arxiv.org/abs/0801.3694 , 84kb)

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\\

arXiv:0801.3795

Date: Thu, 24 Jan 2008 16:36:44 GMT (37kb)

Title: Trapped p-wave superfluids: a local density approach

Authors: M. Iskin and C. J. Williams

Categories: cond-mat.supr-con cond-mat.other

Comments: 4 pages and 4 figures, to be submitted to PRA

\\

The local density approximation is used to study the ground state superfluid

properties of harmonically trapped p-wave Fermi gases as a function of

fermion-fermion attraction strength. While the density distribution is bimodal

on the weakly attracting BCS side, it becomes unimodal with increasing

attraction and saturates towards the BEC side. This non-monotonic evolution is

related to the topological gapless to gapped phase transition, and may be

observed via radio-frequency spectroscopy since quasi-particle transfer current

requires a finite threshold only on the BEC side.

\\ ( http://arxiv.org/abs/0801.3795 , 37kb)

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\\

arXiv:0801.3842

Date: Thu, 24 Jan 2008 20:51:54 GMT (94kb)

Title: Long-living Bloch oscillations of matter waves in optical lattices

Authors: M. Salerno, V. V. Konotop, Yu. V. Bludov

Categories: cond-mat.other

Comments: Submitted to Phys. Rev. Lett

\\

It is shown that by properly designing the spatial dependence of the

nonlinearity it is possible to induce long-living Bloch oscillations of a

localized wavepacket in a periodic potential. The results are supported both by

analytical and numerical investigations and are interpreted in terms of matter

wave dynamics displaying dozens of oscillation periods without any visible

distortion of the wave packet.

\\ ( http://arxiv.org/abs/0801.3842 , 94kb)

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The replacements:

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\\

arXiv:0706.0212

replaced with revised version Thu, 17 Jan 2008 21:50:55 GMT (113kb)

Title: Breakdown of the adiabatic limit in low dimensional gapless systems

Authors: Anatoli Polkovnikov and Vladimir Gritsev

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

Comments: 11 pages, 5 figures, to appear in Nature Physics (originally

submitted version)

\\ ( http://arxiv.org/abs/0706.0212 , 113kb)

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\\

arXiv:cond-mat/0611490

replaced with revised version Mon, 21 Jan 2008 13:22:26 GMT (175kb)

Title: Static Properties of Trapped Bose Gases at Finite Temperature: I.

Thomas- Fermi Limit

Authors: M. Benarous and H. Chachou Samet

Categories: cond-mat.stat-mech

Comments: 11 pages, 9 figures, revised version

\\ ( http://arxiv.org/abs/cond-mat/0611490 , 175kb)

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\\

arXiv:0712.1265

replaced with revised version Mon, 21 Jan 2008 19:26:46 GMT (214kb)

Title: The trapped two-dimensional Bose gas: from Bose-Einstein condensation to

Berezinskii-Kosterlitz-Thouless physics

Authors: Zoran Hadzibabic (LKB - Lhomond), Peter Kr\"uger (LKB - Lhomond), Marc

Cheneau (LKB - Lhomond), Steffen Patrick Rath (LKB - Lhomond), Jean Dalibard

(LKB - Lhomond)

Categories: cond-mat.other

Comments: 21 pages, 6 figures

Proxy: ccsd hal-00194992

\\ ( http://arxiv.org/abs/0712.1265 , 214kb)

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\\

arXiv:0705.1256

replaced with revised version Mon, 21 Jan 2008 16:36:39 GMT (344kb)

Title: Memory-built-in quantum teleportation with photonic and atomic qubits

Authors: Yu-Ao Chen, Shuai Chen, Zhen-Sheng Yuan, Bo Zhao, Chih-Sung Chuu,

Joerg Schmiedmayer and Jian-Wei Pan

Categories: quant-ph

Comments: 19 pages 3 figures 1 table

DOI: 10.1038/nphys832

\\ ( http://arxiv.org/abs/0705.1256 , 344kb)

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\\

arXiv:0705.2426

replaced with revised version Tue, 22 Jan 2008 21:48:00 GMT (33kb)

Title: Vortex Lattice Locking in Rotating Two-Component Bose-Einstein

Condensates

Authors: Ryan Barnett, Gil Refael, Mason A. Porter, Hans Peter Buchler

Categories: cond-mat.str-el cond-mat.mes-hall nlin.PS physics.atom-ph

Comments: 4.2 pages

\\ ( http://arxiv.org/abs/0705.2426 , 33kb)

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\\

arXiv:0711.0653

replaced with revised version Wed, 23 Jan 2008 16:59:54 GMT (334kb)

Title: Destroying superfluidity by rotating a Fermi gas at unitarity

Authors: I. Bausmerth, A. Recati, S. Stringari

Categories: cond-mat.soft cond-mat.supr-con

Comments: 5 pages, 4 figures; comments added; 2 figures changed according to

new results; inset Fig.2 corrected; accepted for publication in Phys. Rev.

Lett

\\ ( http://arxiv.org/abs/0711.0653 , 334kb)

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\\

arXiv:0711.2598

replaced with revised version Wed, 23 Jan 2008 18:33:12 GMT (412kb)

Title: Magnetic trapping of a cold Rb-Cs atomic mixture

Authors: M. L. Harris, P. Tierney, S. L. Cornish

Categories: cond-mat.other

Comments: 16 pages, 5 figures Added references, corrected typos, minor changes

to figures and text

\\ ( http://arxiv.org/abs/0711.2598 , 412kb)

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\\

arXiv:0801.2795

replaced with revised version Wed, 23 Jan 2008 19:37:35 GMT (27kb)

Title: Bose-Einstein condensation in antiferromagnets close to the saturation

field

Authors: D. Reyes, M. A. Continentino and A. Paduan-Filho

Categories: cond-mat.str-el

Comments: 4 pages, 1 figure. Accepted for publication in PRB,

\\ ( http://arxiv.org/abs/0801.2795 , 27kb)

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\\

arXiv:0710.1984

replaced with revised version Thu, 24 Jan 2008 10:49:24 GMT (229kb)

Title: Density Modulations in an Elongated BEC Released from a Disordered

Potential: What Can We Learn ?

Authors: David Cl\'ement (LCFIO), Philippe Bouyer (LCFIO), Alain Aspect

(LCFIO), Laurent Sanchez-Palencia (LCFIO)

Categories: cond-mat.other quant-ph

Proxy: ccsd hal-00178074

\\ ( http://arxiv.org/abs/0710.1984 , 229kb)

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\\

arXiv:0710.4402

replaced with revised version Wed, 23 Jan 2008 21:24:11 GMT (174kb)

Title: Control of Optical Dynamic Memory Capacity of an Atomic Bose-Einstein

Condensate

Authors: Devrim Tarhan, Alphan Sennaroglu, Ozgur E. Mustecaplioglu

Categories: quant-ph cond-mat.other

Comments: 4 figures, 11 pages

\\ ( http://arxiv.org/abs/0710.4402 , 174kb)

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Till next time,

Matt.

-- ========================================================================= Dr M. J. Davis, Senior Lecturer in Physics School of Physical Sciences, email: mdavis_at_physics.uq.edu.au University of Queensland, ph : +61 7 334 69824 Brisbane, QLD 4072, fax : +61 7 336 51242 Australia. http://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 Feb 01 2008 - 10:16:26 EST

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