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

Date: Mon, 5 Jun 2006 09:13:54 +1000 (EST)

Date: Mon, 5 Jun 2006 09:13:54 +1000 (EST)

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

Home page:

http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/

The abstracts for this week:

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Paper: cond-mat/0605648

Date: Fri, 26 May 2006 10:53:47 GMT (32kb)

Title: Motion of a vortex line near the boundary of a semi-infinite uniform

condensate

Authors: Peter Mason, Natalia G. Berloff and Alexander L. Fetter

Comments: submitted to Phys Rev A

Subj-class: Soft Condensed Matter

\\

We consider the motion of a vortex in an asymptotically homogeneous

condensate bounded by a solid wall where the wave function of the condensate

vanishes. For a vortex parallel to the wall, the motion is essentially

equivalent to that generated by an image vortex, but the depleted surface layer

induces an effective shift in the position of the image compared to the case of

a vortex pair in an otherwise uniform flow. Specifically, the velocity of the

vortex can be approximated by $U \approx (\hbar/2m)(y_0-\sqrt 2 \xi)^{-1}$,

where $y_0$ is the distance from the center of the vortex to the wall, $\xi$ is

the healing length of the condensate and $m$ is the mass of the boson.

\\ ( http://arXiv.org/abs/cond-mat/0605648 , 32kb)

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Paper: cond-mat/0605663

Date: Fri, 26 May 2006 19:11:05 GMT (120kb)

Title: Critical Casimir force in $^4$He films: confirmation of finite-size

scaling

Authors: A. Ganshin, S. Scheidemantel, R. Garcia and M. H. W. Chan

Comments: 4 pages, 3 figures, submitted to PRL

Subj-class: Soft Condensed Matter

\\

We present new capacitance measurements of critical Casimir force-induced

thinning of $^4$He films near the superfluid/normal transition, focused on the

region below $T_{\lambda}$ where the effect is the greatest. $^4$He films of

238, 285, and 340 \AA thickness are adsorbed on N-doped silicon substrates with

roughness $\approx 8 {\AA}$. The Casimir force scaling function $\vartheta $,

deduced from the thinning of these three films, collapses onto a single

universal curve, attaining a minimum $\vartheta = -1.30 \pm 0.03$ at

$x=td^{1/\nu}=-9.7\pm 0.8 {\AA}^{1/\nu}$. The collapse confirms the finite-size

scaling origin of the dip in the film thickness. Separately, we also confirm

the presence down to $2.13 K$ of the Goldstone/surface fluctuation force, which

makes the superfluid film $\sim 2 {\AA}$ thinner than the normal film.

\\ ( http://arXiv.org/abs/cond-mat/0605663 , 120kb)

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Paper: cond-mat/0603162

replaced with revised version Fri, 26 May 2006 05:55:17 GMT (152kb)

Title: Bose-Fermi mixtures in an optical lattice

Authors: K. Sengupta, N. Dupuis, and P. Majumdar

Comments: v2, minor change

Subj-class: Strongly Correlated Electrons

\\ ( http://arXiv.org/abs/cond-mat/0603162 , 152kb)

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Paper: cond-mat/0603643

replaced with revised version Fri, 26 May 2006 05:56:00 GMT (61kb)

Title: The 1D interacting anyon gas: low-energy properties and Haldane

exclusion statistics

Authors: M.T. Batchelor, X.-W. Guan and N. Oelkers

Comments: 4 pages, 2 figures, minor corrections, to appear in Phys. Rev. Lett

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0603643 , 61kb)

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Paper: physics/0605231

Date: Fri, 26 May 2006 05:55:59 GMT (24kb)

Title: Competition between Electromagnetically Induced Transparency and Raman

Processes

Authors: G. S. Agarwal, T. N. Dey, and Daniel J. Gauthier

Comments: 3.5 pages, 7 figures

Subj-class: Optics

\\

We present a theoretical formulation of competition among electromagnetically

induced transparency (EIT) and Raman processes. The latter become important

when the medium can no longer be considered to be dilute. Unlike the standard

formulation of EIT, we consider all fields applied and generated as interacting

with both the transitions of the $\Lambda$ scheme. We solve Maxwell equations

for the net generated field using a fast-Fourier-transform technique and obtain

predictions for the probe, control and Raman fields. We show how the intensity

of the probe field is depleted at higher atomic number densities due to the

build up of multiple Raman fields.

\\ ( http://arXiv.org/abs/physics/0605231 , 24kb)

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Paper: cond-mat/0605684

Date: Sun, 28 May 2006 10:36:44 GMT (278kb)

Title: Finite temperature effects in trapped Fermi gases with population

imbalance

Authors: Chih-Chun Chien, Qijin Chen, Yan He, and K. Levin

Comments: "No comments!"

Subj-class: Strongly Correlated Electrons; Superconductivity

\\

We study the finite temperature $T$ behavior of trapped Fermi gases as they

undergo BCS-Bose Einstein condensation (BEC) crossover, in the presence of a

population imbalance. Our results, in qualitative agreement with recent

experiments, show how the superfluid phase transition is directly reflected in

the particle density profiles. We demonstrate that at $ T \neq 0$ and in the

near-BEC and unitary regimes, the polarization is excluded from the superfluid

core. Nevertheless a substantial polarization fraction is carried by a normal

region of the trap having strong pair correlations, which we associate with

noncondensed pairs or the ``pseudogap phase''.

\\ ( http://arXiv.org/abs/cond-mat/0605684 , 278kb)

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Paper: cond-mat/0605691

Date: Mon, 29 May 2006 06:59:10 GMT (125kb)

Title: Magnetic disorder and dynamical properties of a Bose-Einstein condensate

in atomic waveguides

Authors: Daw-Wei Wang

Comments: 15 pages and 9 figures. An extended work of Phys. Rev. Lett. 92,

076802 (2004)

Subj-class: Other; Disordered Systems and Neural Networks

\\

We systematically investigate the properties of the quenched disorder

potential in an atomic waveguide, and study its effects to the dynamics of

condensate in the strong disorder region. We show that even very small wire

shape fluctuations can cause strong disorder potential along the wire

direction, leading to the fragmentation phenomena as the condensate is close to

the wire surface. The generic disorder potential is Gaussian correlated random

potential with vanishing correlations in both short and long wavelength limits

and with a strong correlation weight at a finite length scale, set by the

atom-wire distance. When the condensate is fragmentized, we investigate the

coherent and incoherent dynamics of the condensate, and demonstrate that it can

undergo a crossover from a coherent condensate to an insulating Bose-glass

phase in strong disorder (or low density) regime. Our numerical results

obtained within the meanfield approximation are semi-quantitatively consistent

with the experimental results.

\\ ( http://arXiv.org/abs/cond-mat/0605691 , 125kb)

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Paper: cond-mat/0605695

Date: Mon, 29 May 2006 08:33:49 GMT (123kb)

Title: Quantum ratchet with cold atoms in a pair of pulsed optical lattices

Authors: Gabriel G. Carlo, Giuliano Benenti, Giulio Casati, Sandro Wimberger,

Oliver Morsch, Riccardo Mannella, Ennio Arimondo

Comments: 6 pages, 7 figures

Subj-class: Other

\\

We present a very simple model for a readily implementable ratchet system. It

consists of two series of spatially periodic kicks. By means of two parameters

all the symmetries that could prevent us from finding directed transport are

removed. A complete characterization of the behavior of the system is given and

its robustness is checked. We conclude that our model offers a clear-cut way to

implement directed transport in an atom optical experiment.

\\ ( http://arXiv.org/abs/cond-mat/0605695 , 123kb)

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Paper: cond-mat/0605699

Date: Mon, 29 May 2006 09:37:19 GMT (301kb)

Title: Theory of vortex-lattice melting in a one-dimensional optical lattice

Authors: Michiel Snoek and H.T.C. Stoof

Comments: 17 pages, 17 figures, submitted to Phys. Rev. A

Subj-class: Other

\\

We investigate quantum and temperature fluctuations of a vortex lattice in a

one-dimensional optical lattice. We discuss in particular the Bloch bands of

the Tkachenko modes and calculate the correlation function of the vortex

positions along the direction of the optical lattice. Because of the small

number of particles in the pancake Bose-Einstein condensates at every site of

the optical lattice, finite-size effects become very important. Moreover, the

fluctuations in the vortex positions are inhomogeneous due to the inhomogeneous

density. As a result, the melting of the lattice occurs from the outside

inwards. However, tunneling between neighboring pancakes substantially reduces

the inhomogeneity as well as the size of the fluctuations. On the other hand,

nonzero temperatures increase the size of the fluctuations dramatically. We

calculate the crossover temperature from quantum melting to classical melting.

We also investigate melting in the presence of a quartic radial potential,

where a liquid can form in the center instead of at the outer edge of the

pancake Bose-Einstein condensates.

\\ ( http://arXiv.org/abs/cond-mat/0605699 , 301kb)

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Paper: cond-mat/0605708

Date: Mon, 29 May 2006 15:49:43 GMT (953kb)

Title: Expansion dynamics of a dipolar Bose-Einstein condensate

Authors: S. Giovanazzi, P. Pedri, L. Santos, A. Griesmaier, M. Fattori, T.

Koch, J. Stuhler, T. Pfau

Comments: 12 pages. Submitted to PRA

Subj-class: Other

\\

Our recent measurements on the expansion of a chromium dipolar condensate

after release from an optical trapping potential are in good agreement with an

exact solution of the hydrodynamic equations for dipolar Bose gases. We report

here the theoretical method used to interpret the measurement data as well as

more details of the experiment and its analysis. The theory reported here is a

tool for the investigation of different dynamical situations in time-dependent

harmonic traps.

\\ ( http://arXiv.org/abs/cond-mat/0605708 , 953kb)

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Paper: cond-mat/0605711

Date: Mon, 29 May 2006 18:39:37 GMT (61kb)

Title: Fragmentation of Bose-Einstein Condensates

Authors: Erich J. Mueller (Cornell), Tin-Lun Ho (OSU), Masahito Ueda (Tokyo

Institute of Technology) and Gordon Baym (UIUC)

Comments: 16 pages, 1 figure, revtex4

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\

We present the theory of bosonic systems with multiple condensates, unifying

disparate models which are found in the literature, and discuss how

degeneracies, interactions, and symmetries conspire to give rise to this

unusual behavior. We show that as degeneracies multiply, so do the types of

fragmentation, eventually leading to strongly correlated states with no trace

of condensation.

\\ ( http://arXiv.org/abs/cond-mat/0605711 , 61kb)

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Paper: cond-mat/0510301

replaced with revised version Sun, 28 May 2006 10:17:21 GMT (478kb)

Title: Phase Separation of a Fast Rotating Boson-Fermion Mixture in the

Lowest-Landau-Level Regime

Authors: Rina Kanamoto, Makoto Tsubota

Subj-class: Mesoscopic Systems and Quantum Hall Effect; Other

Journal-ref: Phys. Rev. Lett. 96, 200405 (2006)

\\ ( http://arXiv.org/abs/cond-mat/0510301 , 478kb)

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Paper: cond-mat/0601289

replaced with revised version Sat, 27 May 2006 09:06:24 GMT (7kb)

Title: Force on a moving point impurity due to quantum fluctuations in a

Bose-Einstein condensate

Authors: D. C. Roberts

Comments: v2: corrected notation and other minor changes

Subj-class: Statistical Mechanics; Other

\\ ( http://arXiv.org/abs/cond-mat/0601289 , 7kb)

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Paper: cond-mat/0602346

replaced with revised version Mon, 29 May 2006 17:26:12 GMT (610kb)

Title: Population and Phase Coherence during the Growth of an Elongated

Bose-Einstein Condensate

Authors: Mathilde Hugbart (LCFIO), Jocelyn A. Retter (LCFIO), Andres Var\`{o}n

(LCFIO), Philippe Bouyer (LCFIO), Alain Aspect (LCFIO), Matthew J. Davis (ARC

QUANTUM OPTICS)

Proxy: ccsd ccsd-00018350

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0602346 , 610kb)

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Paper: cond-mat/0603498

replaced with revised version Mon, 29 May 2006 05:51:42 GMT (682kb)

Title: Pairing in a three component Fermi gas

Authors: T. Paananen, J.-P. Martikainen, and P. Torma

Comments: 10 pages, 3 figures

Subj-class: Superconductivity

Journal-ref: Phys. Rev. A 73, 053606 (2006)

\\ ( http://arXiv.org/abs/cond-mat/0603498 , 682kb)

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Paper: quant-ph/0605231

Date: Sat, 27 May 2006 13:34:01 GMT (135kb)

Title: A single cold atom as efficient stationary source of EPR-entangled light

Authors: David Vitali, Giovanna Morigi, J\"urgen Eschner

Comments: 13 pages, 5 figures

\\

The Stokes and anti-Stokes components of the spectrum of resonance

fluorescence of a single trapped atom, which originate from the mechanical

coupling between the scattered photons and the quantized motion of the atomic

center of mass, exhibit quantum correlations which are of two-mode-squeezing

type. We study and demonstrate the build-up of such correlations in a specific

setup, which is experimentally accessible, and where the atom acts as efficient

and continuous source of EPR-entangled, two-mode squeezed light.

\\ ( http://arXiv.org/abs/quant-ph/0605231 , 135kb)

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Paper: quant-ph/0605234

Date: Mon, 29 May 2006 07:00:43 GMT (209kb)

Title: Integration of fiber coupled high-Q silicon nitride microdisks with

magnetostatic atom chips

Authors: Paul E. Barclay, Kartik Srinivasan, Oskar Painter, Benjamin Lev, Hideo

Mabuchi

\\

Micron scale silicon nitride (SiNx) microdisk optical resonators fabricated

on a silicon wafer are demonstrated with Q = 3.6 x 10^6 (finesse = 5 x 10^4)

and an effective mode volume of 15 (\lambda / n)^3 at wavelengths \lambda ~ 852

nm resonant with the D2 transition manifold of cesium. A dilute hydrofluoric

wet etch is shown to provide sensitive tuning of the microdisk optical

resonances, and robust mounting of a fiber taper provides efficient fiber optic

coupling to the SiNx microdisk cavities while allowing unfettered optical

access for laser cooling and trapping of atoms. Initial measurement of a hybrid

atom-cavity chip indicates that cesium adsorption on the surface of the SiNx

microdisks results in significant red-detuning of the disk resonances. A

technique for parallel integration of multiple (10) microdisks with a single

optical fiber taper is also demonstrated.

\\ ( http://arXiv.org/abs/quant-ph/0605234 , 313kb)

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Paper: quant-ph/0605237

Date: Mon, 29 May 2006 08:25:32 GMT (157kb)

Title: Estimation of fluctuating magnetic fields by an atomic magnetometer

Authors: Vivi Petersen and Klaus Molmer

Comments: 8 pages, 6 figures

\\

We present a theoretical analysis of the ability of atomic magnetometers to

estimate a fluctuating magnetic field. Our analysis makes use of a Gaussian

state description of the atoms and the probing field, and it presents the

estimator of the field and a measure of its uncertainty which coincides in the

appropriate limit with the achievements for a static field. We show by

simulations that the estimator for the current value of the field

systematically lags behind the actual value of the field, and we suggest a more

complete theory, where measurement results at any time are used to update and

improve both the estimate of the current value and the estimate of past values

of the B-field.

\\ ( http://arXiv.org/abs/quant-ph/0605237 , 157kb)

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Paper: quant-ph/0605238

Date: Mon, 29 May 2006 09:25:53 GMT (2kb)

Title: Erratum : Squeezing and entanglement delay using slow light

Authors: G. Hetet, A. Peng, M. T. Johnsson, M. T. L. Hsu, O. Gloeckl, P. K.

Lam, H .A. Bachor, and J. J. Hope

Comments: 1 page, no figure

\\

An inconsistency was found in the equations used to calculate the variance of

the quadrature fluctuations of a field propagating through a medium

demonstrating electromagnetically induced transparency (EIT). The decoherence

term used in our original paper introduces inconsistency under weak probe

approximation. In this erratum we give the Bloch equations with the correct

dephasing terms. The conclusions of the original paper remain the same. Both

entanglement and squeezing can be delayed and preserved using EIT without

adding noise when the decoherence rate is small.

\\ ( http://arXiv.org/abs/quant-ph/0605238 , 2kb)

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Paper: quant-ph/0605244

Date: Mon, 29 May 2006 16:27:04 GMT (11kb)

Title: Stochastic One-Way Quantum Computing with Ultracold Atoms in Optical

Lattices

Authors: Michael C. Garrett and David L. Feder

Comments: 4 pages, 2 figures, REVTeX, Qcircuit.tex included

\\

The cluster state, the highly entangled multipartite initial state required

for one-way quantum computing, can be generated from a gas of ultracold atoms

confined in a 2D optical lattice. In practice, a systematic phase error is

expected, resulting in imperfect cluster states. We present a solution to this

problem, wherein the teleportation protocol is necessarily stochastic if the

value of the phase error is not known.

\\ ( http://arXiv.org/abs/quant-ph/0605244 , 11kb)

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Paper: quant-ph/0605245

Date: Mon, 29 May 2006 17:46:19 GMT (66kb)

Title: Manipulating Single Neutral Atoms in Optical Lattices

Authors: Chuanwei Zhang, S. L. Rolston, and S. Das Sarma

Comments: 5 pages, 3 figures

\\

We analyze a scheme to manipulate quantum states of neutral atoms at

individual sites of optical lattices using focused laser beams. Spatial

distributions of focused laser intensities induce position-dependent energy

shifts of hyperfine states, which, combined with microwave radiation, allow

selective manipulation of quantum states of individual target atoms. We show

that various errors in the manipulation process are suppressed below $% 10^{-4}

$ with properly chosen microwave pulse sequences and laser parameters. A

similar idea is also applied to measure quantum states of single atoms in

optical lattices.

\\ ( http://arXiv.org/abs/quant-ph/0605245 , 66kb)

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Paper: cond-mat/0605736

Date: Tue, 30 May 2006 15:02:45 GMT (152kb)

Title: Long Distance Transport of Ultracold Atoms using a 1D optical lattice

Authors: Stefan Schmid, Gregor Thalhammer, Klaus Winkler, Florian Lang, and

Johannes Hecker Denschlag

Comments: 15 pages, 8 figures

Subj-class: Other

\\

We study the horizontal transport of ultracold atoms over macroscopic

distances of up to 20 cm with a moving 1D optical lattice. By using an optical

Bessel beam to form the optical lattice, we can achieve almost homogeneous

trapping conditions over the full transport length, which is necessary to hold

the atoms against gravity for such a wide range. Fast transport velocities of

up to 6 m/s (corresponding to about 1100 photon recoils) and accelerations of

up to 2600 m/s^2 are reached. Even at high velocities the momentum of the atoms

is precisely defined with an uncertainty of less than one photon recoil. This

allows for construction of an atom catapult with high kinetic energy

resolution, which might have applications in novel collision experiments.

\\ ( http://arXiv.org/abs/cond-mat/0605736 , 152kb)

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Paper: cond-mat/0605743

Date: Tue, 30 May 2006 18:30:58 GMT (21kb)

Title: Cyclic Lattice Feshbach Resonances

Authors: Fei Zhou (PITP, Ubc)

Comments: 4 pages, 2 figures included

Subj-class: Other

\\

In this Letter we illustrate the possible cyclic fermion pairing states

across Feshbach resonances in optical lattices. In cyclic fermion pairing, the

pairing amplitude exhibits an oscillatory behavior as the detuning varies. We

estimate the quasi-particle gaps in different regimes of the resonances.

\\ ( http://arXiv.org/abs/cond-mat/0605743 , 21kb)

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Paper: cond-mat/0605744

Date: Tue, 30 May 2006 18:51:49 GMT (60kb)

Title: Finite temperature phase diagram of a polarised Fermi condensate

Authors: M. M. Parish, F. M. Marchetti, A. Lamacraft and B. D. Simons

Comments: 5 pages, 4 figures

Subj-class: Other

\\

The two-component Fermi gas is the simplest fermion system displaying

superfluidity, and as such finds applications ranging from the theory of

superconductivity to QCD. Ultracold atomic gases provide an exceptionally clean

realization of this system, where the interatomic interaction and the atom

species population are both independent, tuneable parameters. This allows one

to investigate the Fermi gas with imbalanced spin populations, which had

previously been experimentally elusive, and this prospect has stimulated much

theoretical activity. Here we show that the finite temperature phase diagram

contains a region of phase separation between the superfluid and normal states

that touches the boundary of second-order superfluid transitions at a

tricritical point, reminiscent of the phase diagram of $^3$He-$^4$He mixtures.

A variation of interaction strength then results in a line of tricritical

points that terminates at zero temperature on the molecular Bose-Einstein

condensate (BEC) side. On this basis, we argue that tricritical points will

play an important role in the recent experiments on polarised atomic Fermi

gases.

\\ ( http://arXiv.org/abs/cond-mat/0605744 , 60kb)

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Paper (*cross-listing*): nucl-th/0605071

Date: Fri, 26 May 2006 13:59:25 GMT (13kb)

Date (revised v2): Mon, 29 May 2006 10:33:24 GMT (13kb)

Title: Cold asymmetrical fermion superfluids in nonperturbative renormalisation

group

Authors: Boris Krippa

Comments: 11 pages, 2 figures, revtex

Subj-class: Nuclear Theory; Superconductivity

\\

The application of the nonperturbative renormalisation group approach to a

system with two fermion species is studied. Assuming a simple ansatz for the

effective action with effective bosons, describing pairing effects we derive a

set of approximate flow equations for the effective coupling including boson

and fermionic fluctuations. The case of two fermions with different masses but

coinciding Fermi surfaces is considered.

The phase transition to a phase with broken symmetry is found at a critical

value of the running scale. The large mass difference is found to disfavour the

formation of pairs.

The mean-field results are recovered if the effects of boson loops are

omitted. While the boson fluctuation effects were found to be negligible for

large values of $p_{F} a$ they become increasingly important with decreasing

$p_{F} a$ thus making the mean field description less accurate.

\\ ( http://arXiv.org/abs/nucl-th/0605071 , 13kb)

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Paper: cond-mat/0601650

replaced with revised version Tue, 30 May 2006 19:30:14 GMT (31kb)

Title: Dynamics of the Bose-Hubbard model: transition from Mott insulator to

superfluid

Authors: Fernando M. Cucchietti, Bogdan Damski, Jacek Dziarmaga, and Wojciech

H. Zurek

Comments: 6+ pages, the significantly extended version of the former submission

Report-no: LAUR-06-0477

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0601650 , 31kb)

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Paper: cond-mat/0604095

replaced with revised version Tue, 30 May 2006 10:37:04 GMT (151kb)

Title: Tuning the Mott transition in a Bose-Einstein condensate by multi-photon

absorption

Authors: C.E. Creffield and T.S. Monteiro

Comments: Minor changes, this version to be published in Phys. Rev. Lett

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0604095 , 151kb)

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Paper (*cross-listing*): math-ph/0412056

replaced with revised version Tue, 30 May 2006 14:16:19 GMT (8kb)

Title: Equivalence of Bose-Einstein condensation and symmetry breaking

Authors: Andras Suto

Comments: An error in my summary of previous results (the definition of F') is

corrected. The correction is to be done also in the PRL

Subj-class: Mathematical Physics; Statistical Mechanics

Journal-ref: Phys.Rev.Lett. 94 (2005) 080402

DOI: 10.1103/PhysRevLett.94.080402

\\ ( http://arXiv.org/abs/math-ph/0412056 , 8kb)

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Paper (*cross-listing*): quant-ph/0601083

replaced with revised version Tue, 30 May 2006 08:18:09 GMT (179kb)

Title: Simulating high-temperature superconductivity model Hamiltonians with

atoms in optical lattices

Authors: Alexander Klein and Dieter Jaksch

Comments: 9 pages, 4 figures; title, abstract and introduction changed, more

examples included; accepted for publication in Phys. Rev. A

Subj-class: Quantum Physics; Other

Journal-ref: Phys. Rev. A 73, 053613 (2006)

DOI: 10.1103/PhysRevA.73.053613

\\ ( http://arXiv.org/abs/quant-ph/0601083 , 179kb)

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Paper: cond-mat/0605751

Date: Wed, 31 May 2006 18:16:45 GMT (236kb)

Title: Universal phase diagram of a strongly interacting Fermi gas with

unbalanced spin populations

Authors: Fr\'{e}d\'{e}ric Chevy (LKB - Lhomond)

Comments: 4 pages, 2 figures

Proxy: ccsd ccsd-00077712

Subj-class: Statistical Mechanics

\\

We present a theoretical interpretation of a recent experiment presented in

ref. \cite{Zwierlein06} on the density profile of Fermi gases with unbalanced

spin populations. We show that in the regime of strong interaction, the

boundaries of the three phases observed in \cite{Zwierlein06} can be

characterized by two dimensionless numbers $\eta\_\alpha$ and $\eta\_\beta$.

Using a combination of a variational treatment and a study of the experimental

results, we infer rather precise bounds for these two parameters.

\\ ( http://arXiv.org/abs/cond-mat/0605751 , 236kb)

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Paper: cond-mat/0605754

Date: Wed, 31 May 2006 16:51:13 GMT (21kb)

Title: Spin polarizability of a trapped superfluid Fermi gas

Authors: A. Recati, I. Carusotto, C. Lobo and S. Stringari

Subj-class: Soft Condensed Matter; Other

\\

The polarization produced by the relative displacement of the potentials

trapping two spin species of a dilute Fermi gas with $N_\ua=N_\da$ is

calculated at unitarity by assuming phase separation between the superfluid and

a spin polarized phase at zero temperature. Due to the energy cost associated

with pair breaking, the dipole magnetic polarizability vanishes in the linear

limit and exhibits important deviations from the ideal gas behaviour even for

displacements of the order of the size of the atomic cloud. The magnetic

behaviour in the presence of different trapping frequencies for the two spin

species is also discussed.

\\ ( http://arXiv.org/abs/cond-mat/0605754 , 21kb)

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Paper: cond-mat/0605755

Date: Wed, 31 May 2006 18:25:46 GMT (63kb)

Title: Disorder-Induced Shift of Condensation Temperature for Dilute Trapped

Bose Gases

Authors: Matthias Timmer, Axel Pelster, and Robert Graham

Comments: Author information under

http://www.theo-phys.uni-essen.de/tp/ags/pelster_dir

Subj-class: Disordered Systems and Neural Networks

\\

We determine the leading shift of the Bose-Einstein condensation temperature

for an ultracold dilute atomic gas in a harmonic trap due to weak disorder by

treating both a Gaussian and a Lorentzian spatial correlation for the quenched

disorder potential. Increasing the correlation length from values much smaller

than the geometric mean of the trap scale and the mean particle distance to

much larger values leads first to an increase of the positive shift to a

maximum at this critical length scale and then to a decrease.

\\ ( http://arXiv.org/abs/cond-mat/0605755 , 63kb)

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Paper: quant-ph/0605252

Date: Wed, 31 May 2006 19:07:32 GMT (814kb)

Title: Photoassociation adiabatic passage of ultracold Rb atoms to form

ultracold Rb_2 molecules

Authors: Evgeny A. Shapiro, Moshe Shapiro, Avi Pe'er, and Jun Ye

Comments: RevTex, 23 pages, 9 figures

\\

We theoretically explore photoassociation by Adiabatic Passage of two

colliding cold ^{85}Rb atoms in an atomic trap to form an ultracold Rb_2

molecule in its ground ro-vibrational level. We consider the incoherent thermal

nature of the scattering process in a trap and show that coherent manipulations

of the atomic ensemble, such as adiabatic passage, are feasible if performed

within the coherence time window dictated by the temperature, which is

relatively long for cold atoms. By repeating the coherent process many times

efficient association of the thermal cloud can be achieved. We show that a

sequence of ~2*10^7 pulses of moderate intensities, each lasting ~750 ns, can

efficiently photoassociate an entire atomic ensemble at temperature of 100 \muK

and density of 10^{11} atoms/cm^3. Use of multiple pathways and multiple pulse

sequences makes it easier to populate the target vibrational state.

\\ ( http://arXiv.org/abs/quant-ph/0605252 , 814kb)

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Paper: cond-mat/0506809

replaced with revised version Wed, 31 May 2006 17:55:38 GMT (109kb)

Title: d-wave resonating valence bond states of fermionic atoms in optical

lattices

Authors: Simon Trebst, Ulrich Schollwoeck, Matthias Troyer, Peter Zoller

Comments: 4+ pages, 5 figures

Subj-class: Strongly Correlated Electrons; Superconductivity

\\ ( http://arXiv.org/abs/cond-mat/0506809 , 109kb)

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Paper: cond-mat/0606015

Date: Thu, 1 Jun 2006 16:52:34 GMT (360kb)

Title: Experimental study of the transport of coherent interacting matter-waves

in a 1D random potential induced by laser speckle

Authors: David Cl\'{e}ment (LCFIO), Andr\`{e}s F. Var\`{o}n (LCFIO), Jocelyn A.

Retter (LCFIO), Laurent Sanchez-Palencia (LCFIO), Alain Aspect (LCFIO),

Philippe Bouyer (LCFIO)

Proxy: ccsd ccsd-00077779

Subj-class: Other

\\

We present a detailed analysis of the 1D expansion of a coherent interacting

matterwave (a Bose-Einstein condensate) in the presence of disorder. A 1D

random potential is created via laser speckle patterns. It is carefully

calibrated and the self-averaging properties of our experimental system are

discussed. We observe the suppression of the transport of the BEC in the random

potential. We discuss the scenario of disorder-induced trapping taking into

account the radial extension in our experimental 3D BEC and we compare our

experimental results with the theoretical predictions.

\\ ( http://arXiv.org/abs/cond-mat/0606015 , 360kb)

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Paper: cond-mat/0606029

Date: Thu, 1 Jun 2006 10:15:49 GMT (23kb)

Title: Effect of Dynamics on Finite Systems in Thermal Equilibrium

Authors: Shyamal Biswas

Comments: 4 pages, 2 figures

Subj-class: Statistical Mechanics

\\

We show quantitatively the role of the dynamics of the constituent particles

of a finite sized system in equilibrium with a heat bath. In thermodynamical

systems the dynamics of its constituent particles play no role in determining

the probability of its state under the condition of equilibrium. But the

dynamics is important at very low temperature when thermal de Broglie wave

length of its constituent particles become comparable to the system size. In

that case we show that specific heat of the system can be negative. There is a

discontinuity of specific heat at a constant temperature below which there is

no effect of thermal interaction on the system. We quantitatively discuss the

thermodynamic limit in particular for the case of Bose Einstein condensation.

\\ ( http://arXiv.org/abs/cond-mat/0606029 , 23kb)

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Paper (*cross-listing*): hep-th/0605259

Date: Thu, 25 May 2006 22:51:59 GMT (23kb)

Title: Symmetry Aspects in Nonrelativistic Multi-Scalar Field Models and

Application to a Coupled Two-Species Dilute Bose Gas

Authors: Rudnei O Ramos and Marcus B Pinto

Comments: 8 pages, 1 eps figure, IOP style. Based on a talk given by R. O.

Ramos at the QFEXT05 workshop, Barcelona, Spain, September 5-9, 2005

Subj-class: High Energy Physics - Theory; Soft Condensed Matter

Journal-ref: J.Phys. A39 (2006) 6687-6693

\\

We discuss unusual aspects of symmetry that can happen due to entropic

effects in the context of multi-scalar field theories at finite temperature. We

present their consequences, in special, for the case of nonrelativistic models

of hard core spheres. We show that for nonrelativistic models phenomena like

inverse symmetry breaking and symmetry non-restoration cannot take place, but a

reentrant phase at high temperatures is shown to be possible for some region of

parameters. We then develop a model of interest in studies of Bose-Einstein

condensation in dilute atomic gases and discuss about its phase transition

patterns. In this application to a Bose-Einstein condensation model, however,

no reentrant phases are found.

\\ ( http://arXiv.org/abs/hep-th/0605259 , 23kb)

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Paper: cond-mat/0601681

replaced with revised version Wed, 31 May 2006 20:40:21 GMT (226kb)

Title: Exact Study of the 1D Boson Hubbard Model with a Superlattice Potential

Authors: V.G. Rousseau, D.P. Arovas, M. Rigol, F. H\'ebert, G.G. Batrouni, R.T.

Scalettar

Comments: 13 pages, 23 figures

Subj-class: Other; Strongly Correlated Electrons

Journal-ref: Physical Review B 73, 174516 (2006)

DOI: 10.1103/PhysRevB.73.174516

\\ ( http://arXiv.org/abs/cond-mat/0601681 , 226kb)

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Paper: cond-mat/0602048

replaced with revised version Thu, 1 Jun 2006 13:51:20 GMT (188kb)

Title: Coherent transport of cold atoms in angle-tuned optical lattices

Authors: Roberto Franzosi, Matteo Cristiani, Carlo Sias, Ennio Arimondo

Comments: 8 pages, 5 figures, one section added, in press in Phys. Rev. A

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0602048 , 188kb)

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Paper: cond-mat/0603113

replaced with revised version Wed, 31 May 2006 23:27:28 GMT (27kb)

Title: Stability analysis for $n$-component Bose-Einstein condensate

Authors: David C. Roberts and Masahito Ueda

Comments: v2: added reference

Subj-class: Other; Statistical Mechanics

Journal-ref: Phys. Rev. A 73, 053611 (2006)

\\ ( http://arXiv.org/abs/cond-mat/0603113 , 27kb)

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Paper: quant-ph/0606003

Date: Wed, 31 May 2006 21:13:06 GMT (21kb)

Title: Indirect decoherence in optical lattices and cold gases

Authors: Daniel Braun

Comments: 12 pages, 1 figure

\\

The interaction of two--level atoms with a common heat bath leads to an

effective interaction between the atoms, such that with time the internal

degrees of the atoms become correlated or even entangled. If part of the atoms

remain unobserved this creates additional indirect decoherence for the selected

atoms, on top of the direct decoherence due to the interaction with the heat

bath. I show that indirect decoherence can drastically increase and even

dominate the decoherence for sufficiently large times. I investigate indirect

decoherence through thermal black body radiation quantitatively for atoms

trapped at regular positions in an optical lattice as well as for atoms at

random positions in a cold gas, and show how indirect coherence can be

controlled or even suppressed through experimentally accessible parameters.

\\ ( http://arXiv.org/abs/quant-ph/0606003 , 21kb)

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Paper: quant-ph/0606013

Date: Thu, 1 Jun 2006 15:11:31 GMT (306kb)

Title: Collective coherent population trapping in a thermal field

Authors: M. Macovei, Z. Ficek, C. H. Keitel

Comments: Accepted for publication in Phys. Rev. A

\\

We analyzed the efficiency of coherent population trapping (CPT) in a

superposition of the ground states of three-level atoms under the influence of

the decoherence process induced by a broadband thermal field. We showed that in

a single atom there is no perfect CPT when the atomic transitions are affected

by the thermal field. The perfect CPT may occur when only one of the two atomic

transitions is affected by the thermal field. In the case when both atomic

transitions are affected by the thermal field, we demonstrated that regardless

of the intensity of the thermal field the destructive effect on the CPT can be

circumvented by the collective behavior of the atoms. An analytic expression

was obtained for the populations of the upper atomic levels which can be

considered as a measure of the level of thermal decoherence. The results show

that the collective interaction between the atoms can significantly enhance the

population trapping in that the population of the upper state decreases with

increased number of atoms. The physical origin of this feature was explained by

the semiclassical dressed atom model of the system. We introduced the concept

of multiatom collective coherent population trapping by demonstrating the

existence of collective (entangled) states whose storage capacity is larger

than that of the equivalent states of independent atoms.

\\ ( http://arXiv.org/abs/quant-ph/0606013 , 306kb)

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Paper: quant-ph/0606018

Date: Thu, 1 Jun 2006 18:34:43 GMT (366kb)

Title: Transfer of trapped atoms between two optical tweezer potentials

Authors: Matthias Schulz, Herbert Crepaz, Ferdinand Schmidt-Kaler, Juergen

Eschner, Rainer Blatt

\\

Trapped, laser-cooled rubidium atoms are transferred between two strongly

focused, horizontal, orthogonally intersecting laser beams. The transfer

efficiency is studied as a function of the vertical distance between the beam

axes. Optimum transfer is found when the distance equals the beam waist radius.

Numerical simulations reproduce well the experimental results.

\\ ( http://arXiv.org/abs/quant-ph/0606018 , 366kb)

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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/ ========================================================================= 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 Mon Jun 05 2006 - 09:13:54 EST

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