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

Date: Tue, 15 Aug 2006 02:11:30 +1000 (EST)

Date: Tue, 15 Aug 2006 02:11:30 +1000 (EST)

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

Hi everyone,

Well it turned out that I did take two weeks holiday, and hence this is a catch

up arXiv email: it is a summary of 11 days worth of mailings.

The abstracts:

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Paper: physics/0607248

Date: Thu, 27 Jul 2006 09:34:00 GMT (133kb)

Title: Photodetachment of cold OH- in a multipole ion trap

Authors: S. Trippel, J. Mikosch, R. Berhane, R. Otto, M. Weidemuller, and R.

Wester

Subj-class: Atomic Physics

\\

The absolute photodetachment cross section of OH- anions at a rotational and

translational temperature of 170K is determined by measuring the

detachment-induced decay rate of the anions in a multipole radio-frequency ion

trap. In comparison with previous results, the obtained cross section shows the

importance of the initial rotational state distribution. Using a tomography

scan of the photodetachment laser through the trapped ion cloud, the derived

cross section is model-independent and thus features a small systematic

uncertainty. The tomography also yields the column density of the OH- anions in

the 22-pole ion trap in good agreement with the expected trapping potential of

a large field free region bound by steep potential walls.

\\ ( http://arXiv.org/abs/physics/0607248 , 133kb)

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Paper: physics/0607254

Date: Thu, 27 Jul 2006 14:09:37 GMT (84kb)

Title: Strong relative intensity squeezing by 4-wave mixing in Rb vapor

Authors: C. F. McCormick, V. Boyer, E. Arimondo, P. D. Lett

Comments: Submitted to Optics Letters

Subj-class: Optics; Atomic Physics

\\

We have measured -3.5 dB (-8.1 dB corrected for losses) relative intensity

squeezing between the probe and conjugate beams generated by stimulated,

nondegenerate four-wave mixing in hot rubidium vapor. Unlike early observations

of squeezing in atomic vapors based on saturation of a two-level system, our

scheme uses a resonant nonlinearity based on ground-state coherences in a

three-level system. Since this scheme produces narrowband, squeezed light near

an atomic resonance it is of interest for experiments involving cold atoms or

atomic ensembles.

\\ ( http://arXiv.org/abs/physics/0607254 , 84kb)

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Paper: physics/0512015

replaced with revised version Thu, 27 Jul 2006 07:23:27 GMT (169kb)

Title: A ring trap for ultracold atoms

Authors: Olivier Morizot (LPL), Yves Colombe (LPL), Vincent Lorent (LPL),

H\'{e}l\`{e}ne Perrin (LPL), Barry M. Garraway (DPA, UNIVERSITY OF SUSSEX)

Comments: 4 figures, 10 pages ; the order of the sections has been changed ; to

appear in Phys. Rev. A

Proxy: ccsd ccsd-00015124

Subj-class: Atomic Physics

\\ ( http://arXiv.org/abs/physics/0512015 , 169kb)

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Paper: cond-mat/0607775

Date: Fri, 28 Jul 2006 19:50:46 GMT (375kb)

Title: Superfluid transition in a rotating resonantly-interacting Fermi gas

Authors: Martin Y. Veillette, Daniel E. Sheehy, Leo Radzihovsky and Victor

Gurarie (University Of Colorado)

Comments: 4 pages, 3 figures

Subj-class: Superconductivity

\\

We study a rotating atomic Fermi gas near a narrow s-wave Feshbach resonance

in a uniaxial harmonic trap with frequencies $\Omega_\perp$, $\Omega_z$. Our

primary prediction is the upper-critical angular velocity, $\omega_{c2}

(\delta,T)$, as a function of temperature $T$ and resonance detuning $\delta$,

ranging across the BEC-BCS crossover. The rotation-driven suppression of

superfluidity at $\omega_{c2}$ is quite distinct in the BCS and BEC regimes,

with the former controlled by Cooper-pair depairing and the latter by the

dilution of bosonic molecules. At low $T$ and $\Omega_z\ll\Omega_\perp$, in the

BCS and crossover regimes of $0 \lesssim \delta \lesssim \delta_c$,

$\omega_{c2}$ is implicitly given by $\hbar \sqrt{\omega_{c2}^2

+\Omega_\perp^2}\approx 2\Delta \sqrt{\hbar \Omega_\perp/\epsilon_F}$,

vanishing as $\omega_{c2} \sim\Omega_\perp(1-\delta/\delta_c)^{1/2}$ near

$\delta_c\approx 2\epsilon_{F} + \frac\gamma 2\epsilon_{F}

\ln(\epsilon_F/\hbar\Omega_\perp)$ (with $\Delta$ the BCS gap and $\gamma$

resonance width), and extending bulk result $\hbar\omega_{c2} \approx

2\Delta^2/\epsilon_{F}$ to a finite number of atoms in a trap. In the BEC

regime of $\delta < 0$ we find $\omega_{c2} \to\Omega^-_\perp$, where molecular

superfluidity can only be destroyed by large quantum fluctuations associated

with comparable boson and vortex densities.

\\ ( http://arXiv.org/abs/cond-mat/0607775 , 375kb)

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Paper: cond-mat/0607776

Date: Fri, 28 Jul 2006 19:53:26 GMT (72kb)

Title: The potential energy of a $^{40}$K Fermi gas in the BCS-BEC crossover

Authors: J. T. Stewart, J. P. Gaebler, C. A. Regal, and D. S. Jin

Subj-class: Other

\\

We present a measurement of the potential energy of an ultracold trapped gas

of $^{40}$K atoms in the BCS-BEC crossover and investigate the temperature

dependence of this energy at unitarity. In particular we study the ratio of the

potential energy of the gas at unitarity to that of a non-interacting gas, and

in the T=0 limit we extract the universal many-body parameter $\beta$. We find

$\beta = -0.54^{+0.05}_{-0.12}$; this value is consistent with previous

measurements using $^{6}$Li atoms and also with recent theory and Monte Carlo

calculations. This result demonstrates the universality of ultracold Fermi

gases in the strongly interacting regime.

\\ ( http://arXiv.org/abs/cond-mat/0607776 , 72kb)

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Paper: cond-mat/0603574

replaced with revised version Fri, 28 Jul 2006 02:12:55 GMT (273kb)

Title: Asymmetric double-well potential for single atom interferometry

Authors: A. I. Sidorov, B. J. Dalton, S. M. Whitlock, and F. Scharnberg

Comments: 9 pages, 6 figures

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0603574 , 273kb)

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Paper: cond-mat/0603859

replaced with revised version Fri, 28 Jul 2006 10:33:55 GMT (67kb)

Title: Ground state cooling of atoms in optical lattices

Authors: M. Popp, J. J. Garcia-Ripoll, K. G. H. Vollbrecht, J. I. Cirac

Comments: 12 pages, 7 figures

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0603859 , 67kb)

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Paper: quant-ph/0607200

Date: Fri, 28 Jul 2006 07:49:07 GMT (159kb)

Title: New uncertainty relations for tomographic entropy: Application to

squeezed states and solitons

Authors: Sergio De Nicola, Renato Fedele, Margarita A. Man'ko, Vladimir I.

Man'ko

Comments: 18 pages, 2 figures, to be published in European Physical Journal B

\\

Using the tomographic probability distribution (symplectic tomogram)

describing the quantum state (instead of the wave function or density matrix)

and properties of recently introduced tomographic entropy associated with the

probability distribution, the new uncertainty relation for the tomographic

entropy is obtained. Examples of the entropic uncertainty relation for squeezed

states and solitons of the Bose--Einstein condensate are considered.

\\ ( http://arXiv.org/abs/quant-ph/0607200 , 159kb)

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Paper: quant-ph/0607201

Date: Fri, 28 Jul 2006 08:55:06 GMT (5kb)

Title: Second Quantization and Bogoliubov Approximation

Authors: Bayram Kurucay

\\

Recent experiments with trapped alkali atoms have drawn enormous interest to

the theoretical studies concerning Bose-Einstein condensation. The purpose of

this paper is to review one of the approaches to study bosonic matter at zero

temperature, namely the Bogoliubov approximation. Review of a necessary tool,

the second quantization, will also be made.

\\ ( http://arXiv.org/abs/quant-ph/0607201 , 5kb)

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Paper: cond-mat/0607781

Date: Fri, 28 Jul 2006 22:31:20 GMT (796kb)

Title: Quantized Vortex States of Strongly Interacting Bosons in a Rotating

Optical Lattice

Authors: Rajiv Bhat, B.M.Peden, B.T.Seaman, M.Kramer, L.D.Carr and M.J.Holland

Comments: 12 Pages, 13 Figures, Version 1

Subj-class: Statistical Mechanics

\\

Bose gases in rotating optical lattices combine two important topics in

quantum physics: superfluid rotation and strong correlations. In this paper, we

examine square two-dimensional systems at zero temperature comprised of

strongly repulsive bosons with filling factors of less than one atom per

lattice site. The entry of vortices into the system is characterized by jumps

of 2 pi in the phase winding of the condensate wavefunction. A lattice of size

L X L can have at most L-1 quantized vortices in the lowest Bloch band. In

contrast to homogeneous systems, angular momentum is not a good quantum number

since the continuous rotational symmetry is broken by the lattice. Instead, a

quasi-angular momentum captures the discrete rotational symmetry of the system.

Energy level crossings indicative of quantum phase transitions are observed

when the quasi-angular momentum of the ground-state changes.

\\ ( http://arXiv.org/abs/cond-mat/0607781 , 796kb)

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Paper: cond-mat/0607782

Date: Fri, 28 Jul 2006 23:35:32 GMT (22kb)

Title: BCS-BEC Crossover in the Strongly Correlated Regime of ultra-cold Fermi

gases

Authors: S. G. Bhongale and S. J. J. M. F. Kokkelmans

Comments: 4 pages, 4 figures

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

\\

We study BCS-BEC crossover in the strongly correlated regime of two component

rotating Fermi gases. We predict that the strong correlations induced by

rotation will have the effect of modifying the crossover region relative to the

non-rotating situation. We show via the two particle correlation function that

the crossover smoothly connects the s-wave paired fermionic fractional quantum

Hall state to the bosonic Laughlin state.

\\ ( http://arXiv.org/abs/cond-mat/0607782 , 22kb)

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Paper: cond-mat/0607803

Date: Mon, 31 Jul 2006 15:41:12 GMT (286kb)

Title: BEC-BCS crossover, phase transitions and phase separation in polarized

resonantly-paired superfluids

Authors: Daniel E. Sheehy, Leo Radzihovsky (University of Colorado)

Comments: 76 RevTeX pages, 54 figures

Subj-class: Superconductivity

\\

We study resonantly-paired s-wave superfluidity in a degenerate gas of two

species (hyperfine states labeled by $\uparrow,\downarrow$) of fermionic atoms

when the numbers $N_{\uparrow}$ and $N_{\downarrow}$ of the two species are

{\it unequal}, i.e., the system is "polarized". We find that the continuous

crossover from the Bose-Einstein condensate (BEC) limit of tightly-bound

diatomic molecules to the Bardeen-Cooper-Schrieffer (BCS) limit of weakly

correlated Cooper pairs, studied extensively at equal populations, is

interrupted by a variety of distinct phenomena under an imposed population

difference $\Delta N \equiv N_\uparrow - N_\downarrow$. Our findings are

summarized by a `` polarization\rq\rq ($\Delta N$) versus Feshbach-resonance

detuning ($\delta$) zero-temperature phase diagram, which exhibits regions of

phase separation, a periodic FFLO superfluid, a polarized normal Fermi gas and

a polarized molecular superfluid consisting of a molecular condensate and a

fully polarized Fermi gas. We describe numerous experimental signatures of such

phases and the transitions between them, in particular focusing on their

spatial structure in the inhomogeneous environment of an atomic trap.

\\ ( http://arXiv.org/abs/cond-mat/0607803 , 286kb)

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Paper: cond-mat/0607821

Date: Mon, 31 Jul 2006 14:45:40 GMT (17kb)

Title: The unitary gas in an isotropic harmonic trap: symmetry properties and

applications

Authors: F\'{e}lix Werner (LKB - Lhomond), Yvan Castin (LKB - Lhomond)

Proxy: ccsd ccsd-00088162

Subj-class: Other

\\

We consider N atoms trapped in an isotropic harmonic potential, with s-wave

interactions of infinite scattering length. In the zero-range limit, we obtain

several exact analytical results: mapping between the trapped problem and the

free-space zero-energy problem, separability in hyperspherical coordinates,

SO(2,1) hidden symmetry, and relations between the moments of the trapping

potential energy and the moments of the total energy.

\\ ( http://arXiv.org/abs/cond-mat/0607821 , 17kb)

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Paper: cond-mat/0607828

Date: Mon, 31 Jul 2006 15:40:48 GMT (193kb)

Title: Partially incoherent gap solitons in Bose-Einstein condensates

Authors: I. M. Merhasin, Boris A. Malomed and Y. B. Band

Comments: 8 pages, 9 figures. Physical Review A, in press

Subj-class: Other

\\

We construct families of incoherent matter-wave solitons in a repulsive

degenerate Bose gas trapped in an optical lattice (OL), i.e., gap solitons, and

investigate their stability at zero and finite temperature, using the

Hartree-Fock-Bogoliubov equations. The gap solitons are composed of a coherent

condensate, and normal and anomalous densities of incoherent vapor co-trapped

with the condensate. Both intragap and intergap solitons are constructed, with

chemical potentials of the components falling in one or different bandgaps in

the OL-induced spectrum. Solitons change gradually with temperature. Families

of intragap solitons are completely stable (both in direct simulations, and in

terms of eigenvalues of perturbation modes), while the intergap family may have

a very small unstable eigenvalue (nevertheless, they feature no instability in

direct simulations). Stable higher-order (multi-humped) solitons, and bound

complexes of fundamental solitons are found too.

\\ ( http://arXiv.org/abs/cond-mat/0607828 , 193kb)

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Paper: cond-mat/0607831

Date: Mon, 31 Jul 2006 17:15:48 GMT (473kb)

Title: Correlations in a BEC collision: First-principles quantum dynamics with

150,000 atoms

Authors: P. Deuar and P. D. Drummond

Comments: 4 pages, 4 figures

Subj-class: Other

\\

The quantum dynamics of colliding Bose-Einstein condensates with 150,000

atoms are simulated directly from the Hamiltonian using the stochastic

positive-P method. Two-body correlations between the scattered atoms and their

velocity distribution are found for experimentally accessible parameters.

Hanbury-Brown-Twiss or thermal-like correlations are seen for co-propagating

atoms, while number correlations for counter-propagating atoms are even

stronger than thermal correlations at short times. The coherent phase-grains

grow in size as the collision progresses with the onset of growth coinciding

with the beginning of stimulated scattering. These results demonstrate that

exponentially complex calculations involving over 10^{1,000,000} quantum states

are feasible using existing computers. The method is versatile and usable for a

range of cold atom systems.

\\ ( http://arXiv.org/abs/cond-mat/0607831 , 473kb)

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Paper: cond-mat/0607834

Date: Mon, 31 Jul 2006 18:24:35 GMT (219kb)

Title: Polarized fermions in the unitarity limit

Authors: Gautam Rupak, Thomas Schaefer, Andrei Kryjevski

Comments: 5 pages, 5 figures, LaTeX2e

Subj-class: Other

\\

We consider a polarized Fermi gas in the unitarity limit. Results are

calculated analytically up to next-to-leading order in an expansion about d=4

spatial dimensions. We find a first order transition from superfluid to normal

phase. The critical chemical potential asymmetry for this phase transition is

delta_mu_c= 2/(mu epsilon)*(1-0.467\epsilon), where epsilon=4-d is the

expansion parameter and 'mu' is the average chemical potential of the two

fermion species. Stability of the superfluid phase in the presence of

supercurrents is also studied.

\\ ( http://arXiv.org/abs/cond-mat/0607834 , 219kb)

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Paper: cond-mat/0607835

Date: Mon, 31 Jul 2006 18:59:06 GMT (260kb)

Title: Fermi gas near unitarity around four and two spatial dimensions

Authors: Yusuke Nishida and Dam Thanh Son

Comments: 20 pages, 15 figures, revtex4

Report-no: INT-PUB 06-10, TKYNT-06-10

Subj-class: Other

\\

We construct systematic expansions around four and two spatial dimensions for

a Fermi gas near the unitarity limit. Near four spatial dimensions such a Fermi

gas can be understood as a weakly-interacting system of fermionic and bosonic

degrees of freedom. To the leading and next-to-leading orders in the expansion

over epsilon=4-d, with d being the dimensionality of space, we calculate the

thermodynamic quantities and the fermion quasiparticle spectrum as functions of

the binding energy of the two-body state. Then the phase structure of the

polarized Fermi gas near the unitarity regime is studied from the epsilon

expansion. We found that at unitarity there is a first-order phase transition

from the unpolarized superfluid state to a completely polarized normal state.

On the BEC side of the unitarity point, in a certain range of the two-body

binding energy we find a gapless superfluid phase and a superfluid phase with

spatially varying condensate which occupy a region in the phase diagram between

the gapped superfluid phase and the normal phase. We also show that the unitary

Fermi gas near two spatial dimensions reduces to a weakly-interacting Fermi gas

and calculate the thermodynamic quantities and the fermion quasiparticle

spectrum in the expansion over \bar\epsilon=d-2.

\\ ( http://arXiv.org/abs/cond-mat/0607835 , 260kb)

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Paper: cond-mat/0607706

replaced with revised version Mon, 31 Jul 2006 17:17:33 GMT (139kb)

Title: Transistor-Like Behavior of a Bose-Einstein Condensate in a Triple Well

Potential

Authors: James A. Stickney, Dana Z. Anderson, and Alex A. Zozulya

Comments: 12 pages, 12 figures

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0607706 , 139kb)

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Paper: quant-ph/0607218

Date: Sun, 30 Jul 2006 17:52:26 GMT (300kb)

Title: Quantum coherence and population trapping in three-photon processes

Authors: Caroline Champenois (PIIM), Giovanna Morigi (GRUP D'OPTICA), Juergen

Eschner (ICFO)

Proxy: ccsd ccsd-00088084

\\

The spectroscopic properties of a single, tightly trapped atom are studied,

when the electronic levels are coupled by three laser fields in an $N$-shaped

configuration of levels, whereby a $\Lambda$-type level system is weakly

coupled to a metastable state. We show that depending on the laser frequencies

the response can be tuned from coherent population trapping at two-photon

resonance to novel behaviour at three photon resonance, where the metastable

state can get almost unit occupation in a wide range of parameters. For certain

parameter regimes the system switches spontaneously between dissipative and

coherent dynamics over long time scales.

\\ ( http://arXiv.org/abs/quant-ph/0607218 , 300kb)

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Paper: physics/0607294

Date: Mon, 31 Jul 2006 16:45:18 GMT (811kb)

Title: Precision preparation of strings of trapped neutral atoms

Authors: Y. Miroshnychenko, W. Alt, I. Dotsenko, L. F\"orster, M. Khudaverdyan,

A. Rauschenbeutel and D. Meschede

Comments: 25 pages, 18 figures

Subj-class: Atomic Physics

\\

We have recently demonstrated the creation of regular strings of neutral

caesium atoms in a standing wave optical dipole trap using optical tweezers [Y.

Miroshnychenko et al., Nature, in press (2006)]. The rearrangement is realized

atom-by-atom, extracting an atom and re-inserting it at the desired position

with sub-micrometer resolution. We describe our experimental setup and present

detailed measurements as well as simple analytical models for the resolution of

the extraction process, for the precision of the insertion, and for heating

processes. We compare two different methods of insertion, one of which permits

the placement of two atoms into one optical micropotential. The theoretical

models largely explain our experimental results and allow us to identify the

main limiting factors for the precision and efficiency of the manipulations.

Strategies for future improvements are discussed.

\\ ( http://arXiv.org/abs/physics/0607294 , 811kb)

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Paper: physics/0604140

replaced with revised version Mon, 31 Jul 2006 09:58:29 GMT (292kb)

Title: Theoretical model for ultracold molecule formation via adaptive feedback

control

Authors: Ulrich Poschinger, Wenzel Salzmann, Roland Wester, Matthias

Weidemueller, Christiane P. Koch, Ronnie Kosloff

Subj-class: Atomic Physics

\\ ( http://arXiv.org/abs/physics/0604140 , 292kb)

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Paper: cond-mat/0608012

Date: Tue, 1 Aug 2006 06:29:30 GMT (138kb)

Title: Pfaffian-like ground state for 3-body-hard-core bosons in 1D lattices

Authors: B. Paredes, T. Keilmann, J. I. Cirac

Subj-class: Other

\\

We propose a Pfaffian-like Ansatz for the ground state of bosons subject to

3-body infinite repulsive interactions in a 1D lattice. Our Ansatz consists of

the symmetrization over all possible ways of distributing the particles in two

identical Tonks-Girardeau gases. We support the quality of our Ansatz with

numerical calculations and propose an experimental scheme based on mixtures of

bosonic atoms and molecules in 1D optical lattices in which this Pfaffian-like

state could be realized. Our findings may open the way for the creation of

non-abelian anyons in 1D systems.

\\ ( http://arXiv.org/abs/cond-mat/0608012 , 138kb)

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Paper: cond-mat/0602622

replaced with revised version Tue, 1 Aug 2006 14:55:11 GMT (68kb)

Title: Anderson localization of elementary excitations in a one dimensional

Bose-Einstein condensate

Authors: Nicolas Bilas and Nicolas Pavloff Comments: 11 pages, 6 figures. Final

printed version

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0602622 , 68kb)

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Paper: cond-mat/0608053

Date: Wed, 2 Aug 2006 16:56:14 GMT (38kb)

Title: Global singularity-free solution of the Iordanskii force problem

Authors: Markus Flaig and Uwe R. Fischer

Comments: 7 pages of RevTex4, 1 figure

Subj-class: Other

\\

We present a derivation of the transverse force acting on a hydrodynamic

vortex in the presence of an incoming sound wave from a global solution of the

scattering problem, using the method of matched asymptotic expansions. The

solution presented includes a detailed treatment of the interaction of the

incident wave with the vortex core, and is free from the singularities in the

momentum exchange between vortex and sound wave which have led to contradictory

results for the value of the transverse force in the literature.

\\ ( http://arXiv.org/abs/cond-mat/0608053 , 38kb)

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Paper: cond-mat/0605039

replaced with revised version Wed, 2 Aug 2006 17:41:04 GMT (61kb)

Title: Intermediate temperature superfluidity in an atomic Fermi gas with

population imbalance

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

Comments: 4 pages, 4 EPS figures, clarified the discussions about stability

conditions, added a new inset to Fig.3

Subj-class: Strongly Correlated Electrons; Superconductivity

\\ ( http://arXiv.org/abs/cond-mat/0605039 , 61kb)

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Paper: quant-ph/0309149

replaced with revised version Wed, 2 Aug 2006 13:59:30 GMT (159kb)

Title: Directed motion for delta-kicked atoms with broken symmetries:

comparison between theory and experiment

Authors: P. H. Jones, M. Goonasekera, D. R. Meacher, T. Jonckheere, T. S.

Monteiro

Comments: 5 pages, 5 figures Now includes experimental data on time evolution

and comparison with theory

\\ ( http://arXiv.org/abs/quant-ph/0309149 , 159kb)

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Paper: physics/0608021

Date: Wed, 2 Aug 2006 14:08:19 GMT (235kb)

Title: From Optical Lattice Clocks to the Measurement of Forces in the Casimir

Regime

Authors: Peter Wolf (LNE-SYRTE, BIPM), Pierre Lemonde (LNE-SYRTE), Astrid

Lambrecht (LKB - Jussieu), Sebastien Bize (LNE-SYRTE), Arnaud Landragin

(LNE-SYRTE), Andre Clairon (LNE-SYRTE)

Comments: 10 pages, to be published in the Proceedings of the 2006 IEEE

Frequency Control Symposium

Proxy: ccsd ccsd-00088469

Subj-class: Atomic Physics

\\

We propose a novel experiment based on atoms trapped close to a macroscopic

surface, to study the interactions between the atoms and the surface at very

small separations (0.6 to 10 $\mu$m). In this range the dominant potential is

the QED interaction (Casimir-Polder and Van der Waals) between the surface and

the atom. Additionally, several theoretical models suggest the possibility of

Yukawa type potentials with sub-mm range, arising from new physics related to

gravity. We propose a set-up very similar to neutral atom optical lattice

clocks, but with the atoms trapped in lattice sites close to the reflecting

mirror. A sequence of pulses of the probe laser at different frequencies is

then used to create an interferometer with a coherent superposition between

atomic states at different distances from the mirror. Assuming state of the art

measurements, we expect that such an experiment would improve the best existing

measurements of the atom-wall QED interaction by ≥2 orders of magnitude,

whilst gaining up to 4 orders of magnitude on the best present limits on new

interactions in the range between 100 nm and 100 $\mu$m.

\\ ( http://arXiv.org/abs/physics/0608021 , 235kb)

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Paper: cond-mat/0608091

Date: Thu, 3 Aug 2006 15:37:09 GMT (35kb)

Title: Modulation spectroscopy with ultracold fermions in an optical lattice

Authors: C. Kollath, A. Iucci, I. McCulloch, and T. Giamarchi Subj-class:

Superconductivity

\\

We propose an experimental setup of ultracold fermions in an optical lattice

to determine the pairing gap in a superfluid state and the spin ordering in a

Mott-insulating state. The idea is to apply a periodic modulation of the

lattice potential and to use the thereby induced double occupancy to probe the

system.

We show by full time-dependent calculation using the adaptive time dependent

density-matrix renormalization group method that the position of the peak in

the spectrum of the induced double occupancy gives the pairing energy in a

superfluid and the interaction energy in a Mott-insulator, respectively. In the

Mott-insulator we relate the spectral weight of the peak to the spin ordering

at finite temperature using perturbative calculations.

\\ ( http://arXiv.org/abs/cond-mat/0608091 , 35kb)

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Paper: cond-mat/0603721

replaced with revised version Thu, 3 Aug 2006 15:54:43 GMT (52kb)

Title: Spectroscopy of ultracold atoms by periodic lattice modulations

Authors: C. Kollath, A. Iucci, T. Giamarchi, W. Hofstetter, U. Schollwoeck

Subj-class: Other

Journal-ref: Phys. Rev. Lett. 97, 050402 (2006)

DOI: 10.1103/PhysRevLett.97.050402

\\ ( http://arXiv.org/abs/cond-mat/0603721 , 52kb)

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Paper: physics/0608024

Date: Wed, 2 Aug 2006 20:58:45 GMT (415kb)

Title: Analysis of a Magnetically Trapped Atom Clock

Authors: D. Kadio and Y.B. Band Comments: 11 pages, 6 figures. Accepted for

publication in Phys. Rev. A

Subj-class: Atomic Physics

\\

We consider optimization of a rubidium atom clock that uses magnetically

trapped Bose condensed atoms in a highly elongated trap, and determine the

optimal conditions for minimum Allan variance of the clock using microwave

Ramsey fringe spectroscopy. Elimination of magnetic field shifts and

collisional shifts are considered. The effects of spin-dipolar relaxation are

addressed in the optimization of the clock. We find that a modulational

instability results in phase separation and symmetry breaking of the

two-component condensate composed of the ground and excited hyperfine clock

levels, and this mechanism limits the clock accuracy.

\\ ( http://arXiv.org/abs/physics/0608024 , 415kb)

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Paper: cond-mat/0603334

replaced with revised version Fri, 4 Aug 2006 08:25:51 GMT (33kb)

Title: Phases of Bosons or Fermions in confined optical lattices

Authors: H. Heiselberg

Comments: Revised and extended. To appear in PRA

Subj-class: Superconductivity

\\ ( http://arXiv.org/abs/cond-mat/0603334 , 33kb)

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Paper: cond-mat/0604671

replaced with revised version Fri, 4 Aug 2006 08:48:40 GMT (678kb)

Title: Theory of Ultracold Superstrings

Authors: Michiel Snoek, S. Vandoren, and H.T.C. Stoof

Comments: 16 pages, 9 figures, important factor 2 corrected, accepted for

publication in PRA

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0604671 , 678kb)

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Paper: cond-mat/0606243

replaced with revised version Fri, 4 Aug 2006 12:08:47 GMT (304kb)

Title: A 'Wheel' and 'Axle' description of the Bogoliubov-Anderson phonon in

the BEC/BCS crossover

Authors: Da-Shin Lee, Chi-Yong Lin and Ray J. Rivers

Comments: Four pages, 2 figures. The new version contains additional references

and comments, but is unchanged in all other regards

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0606243 , 304kb)

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Paper: physics/0604026

replaced with revised version Fri, 4 Aug 2006 00:18:22 GMT (576kb)

Title: Electromagnetically Induced Transparency in 6Li

Authors: J. Fuchs, G. J. Duffy, W. J. Rowlands and A. M. Akulshin

Comments: 12 pages, 9 figures

Subj-class: Atomic Physics

\\ ( http://arXiv.org/abs/physics/0604026 , 576kb)

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Paper: cond-mat/0608135

Date: Sat, 5 Aug 2006 05:18:20 GMT (388kb)

Title: Disruption of reflecting Bose-Einstein condensates due to quantum noise

and modulational instability

Authors: R.G. Scott, D.A.W. Hutchinson and C.W. Gardiner

Comments: 5 figures

Subj-class: Other

\\

We perform fully three-dimensional simulations, using the truncated Wigner

method, to investigate the reflection of Bose-Einstein condensates from abrupt

potential barriers. We show that the inter-atomic interactions can produce a

modulational instability in a cigar-shaped cloud with a high atom density at

low approach velocities, disrupting its internal structure, damping the

center-of-mass motion and generating vortices. Furthermore, by incorporating

quantum noise we show that scattering halos form at high approach velocities,

causing an associated condensate depletion. We compare our results to recent

experimental observations.

\\ ( http://arXiv.org/abs/cond-mat/0608135 , 388kb)

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Paper: cond-mat/0608154

Date: Mon, 7 Aug 2006 07:46:32 GMT (16kb)

Title: Pairing and Superfluid Properties of Dilute Fermion Gases at Unitarity

Authors: Vamsi K. Akkineni, D.M. Ceperley, Nandini Trivedi

Comments: 4 pages, 4 figures, To be submitted to PRL

Subj-class: Statistical Mechanics; Superconductivity

\\

We study the system of a dilute gas of fermions in 3-dimensions, with

attractive interactions tuned to the unitarity point, using the

non-perturbative Restricted Path Integral Monte Carlo (R-PIMC) method. The

pairing and superfluid properties of this system are calculated at finite

temperature. The total energy at very low temperature from our results agrees

closely with that of previous ground-state Quantum Monte Carlo calculations. We

identify the temperature $T^\ast\approx 0.70\epsilon_F$ below which pairing

correlations develop, and estimate the critical temperature for the superfluid

transition $T_c\approx 0.25\epsilon_F$ from a finite size scaling analysis of

the superfluid density.

\\ ( http://arXiv.org/abs/cond-mat/0608154 , 16kb)

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Paper: cond-mat/0608171

Date: Mon, 7 Aug 2006 16:23:56 GMT (67kb)

Title: Comparing contact and dipolar interaction in a Bose-Einstein condensate

Authors: Axel Griesmaier, J\"urgen Stuhler, Tobias Koch, Marco Fattori, Tilman

Pfau, and Stefano Giovanazzi Subj-class: Other

\\

We have measured the relative strength $\epsilon_dd$ of the magnetic

dipole-dipole interaction compared to the contact interaction in a chromium

Bose-Einstein condensate. We analyze the asymptotic velocities of expansion of

a dipolar chromium BEC with different orientations of the atomic magnetic

dipole moments. By comparing them with numerical solutions of the hydrodynamic

equations for dipolar condensates, we are able to determine $\epsilon_dd =

0.159\pm0.034$ with high accuracy. Since the absolute strength of the

dipole-dipole interaction is known exactly, the relative strength of the

dipoledipole interaction can be used to determine the s-wave scattering length

$a = 5.08\pm1.06\cdot10^-9 m = 96\pm20 a0$ of 52Cr. This is fully consistent

with our previous measurements on the basis of Feshbach resonances.

\\ ( http://arXiv.org/abs/cond-mat/0608171 , 67kb)

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Paper: cond-mat/0608172

Date: Mon, 7 Aug 2006 17:50:36 GMT (38kb)

Title: Comment on "Superfluid stability in the BEC-BCS crossover" by C.-H. Pao,

S.-T. Wu, and S.-K.-Yip

Authors: Daniel E. Sheehy and Leo Radzihovsky (University of Colorado)

Comments: 4 pages, 2 figures, submitted to Physical Review B

Subj-class: Superconductivity

\\

We point out an error in recent work by Pao et al [Phys. Rev.B {\bf 73},

132506 (2006)], that stems from their use of a necessary but not sufficient

condition [positive compressibility (magnetic susceptibility) and superfluid

stiffness] for the stability of the ground state of a polarized Fermi gas. As a

result, for a range of detunings their proposed ground-state solution is a

local maximum rather than a minimum of the ground state energy, which thereby

invalidates their proposed phase diagram for resonantly interacting fermions

under an imposed population difference.

\\ ( http://arXiv.org/abs/cond-mat/0608172 , 38kb)

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Paper: cond-mat/0604500

replaced with revised version Fri, 4 Aug 2006 21:46:27 GMT (88kb)

Title: Epsilon expansion for a Fermi gas at infinite scattering length Authors:

Yusuke Nishida and Dam Thanh Son

Comments: 4 pages, 4 figures, revtex4; version to appear in Phys. Rev. Lett

Report-no: INT-PUB 06-08, TKYNT-06-06

Subj-class: Other

Journal-ref: Phys. Rev. Lett. 97, 050403 (2006)

DOI: 10.1103/PhysRevLett.97.050403

\\ ( http://arXiv.org/abs/cond-mat/0604500 , 88kb)

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Paper: cond-mat/0606353

replaced with revised version Mon, 7 Aug 2006 04:54:37 GMT (222kb)

Title: Generalized exclusion statistics and degenerate signature of strongly

interacting anyons

Authors: M T Batchelor and X W Guan

Comments: 7 pages, 3 figures, expanded version

Subj-class: Statistical Mechanics; Strongly Correlated Electrons

\\ ( http://arXiv.org/abs/cond-mat/0606353 , 222kb)

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Paper: physics/0608074

Date: Mon, 7 Aug 2006 16:26:41 GMT (63kb)

Title: Measurement of the Temperature Dependence of the Casimir-Polder Force

Authors: J.M. Obrecht, R.J. Wild, M. Antezza, L.P. Pitaevskii, S. Stringari,

E.A. Cornell

Comments: 4 pages, 4 figures, submitted to Physical Review Letters

Subj-class: Atomic Physics

\\

We report on the first measurement of a temperature dependence of the

Casimir-Polder force. This measurement was obtained by positioning a nearly

pure 87-Rb Bose-Einstein condensate a few microns from a dielectric substrate

and exciting its dipole oscillation. Changes in the collective oscillation

frequency of the magnetically trapped atoms result from spatial variations in

the surface-atom force. In our experiment, the dielectric substrate is heated

up to 605 K, while the surrounding environment is kept near room temperature

(310 K). The effect of the Casimir-Polder force is measured to be nearly three

times larger for a 605 K substrate than for a room-temperature substrate,

showing a clear temperature dependence in agreement with theory.

\\ ( http://arXiv.org/abs/physics/0608074 , 63kb)

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Paper: physics/0608058

Date: Sat, 5 Aug 2006 06:19:58 GMT (521kb)

Title: Cinema, Fermi Problems, & General Education

Authors: C.J. Efthimiou, R. Llewellyn

Comments: 15 pages

Subj-class: Physics Education; Physics and Society; Popular Physics

\\

During the past several years the authors have developed a new approach to

the teaching of Physical Science, a general education course typically found in

the curricula of nearly every college and university. This approach, called

`Physics in Films', uses scenes from popular movies to illustrate physical

principles and has excited student interest and improved student performance.

The analyses of many of the scenes in `Physics in Films' are a direct

application of Fermi calculations -- estimates and approximations designed to

make solutions of complex and seemingly intractable problems understandable to

the student non-specialist. The intent of this paper is to provide instructors

with examples they can use to develop skill in recognizing Fermi problems and

making Fermi calculations in their own courses.

\\ ( http://arXiv.org/abs/physics/0608058 , 521kb)

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Paper: physics/0608060

Date: Sat, 5 Aug 2006 10:27:45 GMT (412kb)

Title: Matter-wave soliton control in optical lattices with topological

dislocations

Authors: Yaroslav V. Kartashov, Lluis Torner

Comments: 15 pages, 4 figures, to appear in Physical Review A

Subj-class: Optics

\\

We address the concept of guiding and transporting matter-wave solitons along

the channels of optical lattices made by interference patterns of beams

containing topological wavefront dislocations. The local lattice distortions

that occur around the dislocations cause solitons to move along reconfigurable

paths, a phenomenon that may be used for controlled all-optical manipulation of

Bose-Einstein condensates. Multiple dislocations form traps that can capture

and hold moving solitons. \\ ( http://arXiv.org/abs/physics/0608060 , 412kb)

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Paper: physics/0407064

replaced with revised version Mon, 7 Aug 2006 07:02:52 GMT (849kb)

Title: First observation of feshbach resonances at very low magnetic field in a

133Cs fountain

Authors: H. Marion (SYRTE), S. Bize (SYRTE), L. Cacciapuoti (SYRTE), D. Chambon

(SYRTE), F. Pereira Dos Santos (SYRTE), G. Santarelli (SYRTE), P. Wolf

(SYRTE), A. Clairon (SYRTE), A. Luiten (UWA), M. Tobar (UWA), S. Kokkelmans

(LKB - Lhomond), C. Salomon (LKB - Lhomond)

Comments: 7 pages

Proxy: ccsd ccsd-00002196

Subj-class: Atomic Physics; Other

\\ ( http://arXiv.org/abs/physics/0407064 , 849kb)

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\\

Paper: cond-mat/0603469

replaced with revised version Tue, 8 Aug 2006 05:09:36 GMT (167kb)

Title: Dissociation dynamics of resonantly coupled bose-fermi mixtures in an

optical lattice

Authors: Takahiko Miyakawa and Pierre Meystre

Comments: 10 pages, 10 figures

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0603469 , 167kb)

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Paper: physics/0608083

Date: Mon, 7 Aug 2006 23:52:58 GMT (301kb)

Title: Atom interferometry in a moving guide

Authors: Saijun Wu, Edward J. Su, Mara Prentiss

Comments: 16 pages, 4 figures

Subj-class: Atomic Physics; Optics

\\

We demonstrate a current-controlled magnetic guide that can transport atoms

in the direction perpendicular to the waveguide. We have combined this with a

light pulse Talbot-Lau interferometer that splits and recombines atom

wavepackets along the free propagation direction of the waveguide, resulting in

an interferometric path that encloses area and thus can be used to sense

rotation.

\\ ( http://arXiv.org/abs/physics/0608083 , 301kb)

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Paper: physics/0608088

Date: Tue, 8 Aug 2006 09:41:32 GMT (584kb)

Title: Pulsed evaporative cooling in a radio-frequency trap

Authors: Carlos L. Garrido Alzar (1), H\'el\`ene Perrin (1), Barry M. Garraway

(2), Vincent Lorent (1) ((1) Laboratoire de Physique des Laser,

CNRS-Universit\'e Paris 13, Villetaneuse, France, (2) Department of Physics

and Astronomy, University of Sussex, Brighton, United Kingdom) Comments: 11

pages, 11 figures

Subj-class: Atomic Physics

\\

A theoretical investigation of forced evaporative cooling in radio-frequency

(rf) adiabatic potentials is presented. Supposing the atoms to be trapped by a

rf field RF1, the cooling procedure is developed around a second RF2

radio-frequency source. This second rf field forces the spin state dressed by

RF1 to adiabatically follow a time-evolving quantization axis. The evaporation

is then possible by quenching the adiabatic following spin dynamics. Our

results show that when the frequencies of RF1 and RF2 are comparable,

counter-intuitive evaporation zones appear making this process more efficient.

On the other hand, because of beating between the two rf signals, a pulsed

evaporative cooling scheme seems to be the optimal strategy to reduce the

temperature of the rf-trapped atoms.

\\ ( http://arXiv.org/abs/physics/0608088 , 584kb)

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Paper: physics/0604139

replaced with revised version Tue, 8 Aug 2006 13:51:44 GMT (118kb)

Title: Efficient formation of strongly bound ultracold cesium molecules by

photoassociation with tunneling

Authors: Mihaela Vatasescu, Claude M. Dion, and Olivier Dulieu

Comments: 15 pages with 7 figures

Subj-class: Atomic Physics; Chemical Physics

\\ ( http://arXiv.org/abs/physics/0604139 , 118kb)

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\\

Paper: cond-mat/0608216

Date: Wed, 9 Aug 2006 14:18:41 GMT (10kb)

Title: Non-uniform vortex lattices in inhomogeneous rotating Bose-Einstein

condensates

Authors: Gordon Baym, C. J. Pethick, S. Andrew Gifford, Gentaro Watanabe

Comments: 6 pages, no figures

Report-no: NORDITA-2006-20

Subj-class: Statistical Mechanics

\\

We derive a general framework, in terms of elastic theory, for describing the

distortion of the vortex lattice in a rotating Bose-Einstein condensate at

arbitrary rotation speed and determining the dependence of the distortion on

the density inhomogeneity of the system. In the rapidly rotating limit, we

derive the energetics in terms of Landau levels, including excitation to higher

levels; the distortion depends on the excitation of higher levels as well as on

the density gradient. As we show, the dominant effect of higher Landau levels

in a distorted lattice in equilibrium is simply to renormalize the frequency

entering the lowest Landau level condensate wave function -- from the

transverse trap frequency, $\omega$, to the rotational frequency, $\Omega$, of

the system. Finally, we show how the equilibrium lattice distortion emerges

from elastohydrodynamic theory for inhomogeneous systems.

\\ ( http://arXiv.org/abs/cond-mat/0608216 , 10kb)

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Paper: cond-mat/0607412

replaced with revised version Wed, 9 Aug 2006 14:46:49 GMT (6kb)

Title: Bose-Einstein Condensation and Casimir Effect of Trapped Ideal Bose Gas

in between two Slabs

Authors: Shyamal Biswas

Comments: 4 pages

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0607412 , 6kb)

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Paper: quant-ph/0603054

replaced with revised version Wed, 9 Aug 2006 15:33:42 GMT (183kb)

Title: Elastic vs. inelastic coherent backscattering of laser light by cold

atoms: a master equation treatment

Authors: Vyacheslav Shatokhin, Cord A. M\"uller, Andreas Buchleitner

Comments: 14 pages, 6 figures

Journal-ref: PRA 73, 063813 (2006)

\\ ( http://arXiv.org/abs/quant-ph/0603054 , 183kb)

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Paper: cond-mat/0608233

Date: Wed, 9 Aug 2006 22:37:21 GMT (422kb)

Title: Critical Rotating Frequency for Superfluid Fermionic Gases across

Feshbach Resonance

Authors: Hui Zhai and Tin-Lun Ho

Comments: 4 pages, 2 figures

Subj-class: Superconductivity

\\

We present a method to determine the critical rotational frequencies for

superfluidity of both uniform and trapped Fermi gases across wide Feshbach

resonance. It is found that as one approaches the resonance from the BCS side,

beyond a critical scattering length, pairing is so robust that superfluidity

cannot be destroyed by rotation. Moreover, the critical frequency has a

sequence of jumps revealing the appearance of Landau levels, which are

particularly prominent for systems up to a few thousand particles. For

rotational frequency below an "ultimate" critical frequency, defined to be the

lowest frequency at which the center of the cloud goes normal, a trapped gas

has a superfluid core surrounded by a normal gas, as seen in recent

experiments.

\\ ( http://arXiv.org/abs/cond-mat/0608233 , 422kb)

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Paper: cond-mat/0608246

Date: Thu, 10 Aug 2006 17:39:04 GMT (52kb)

Title: Quantum phase transition in a two-dimensional system of dipoles

Authors: G.E. Astrakharchik, J. Boronat, I.L. Kurbakov, Yu.E. Lozovik

Comments: 4 figures

Subj-class: Superconductivity

\\

The ground-state phase diagram of a two-dimensional Bose system with

dipole-dipole interactions is studied by means of quantum Monte Carlo

technique. Our calculation predicts a quantum phase transition from gas to

solid phase when the density increases. In the gas phase the condensate

fraction is calculated as a function of the density. Using Feynman

approximation, the collective excitation branch is studied and appearance of a

roton minimum is observed. Results of the static structure factor at both sides

of the gas-solid phase are also presented. The Lindeman ratio at the transition

point comes to be $\gamma = 0.230(6)$. The condensate fraction in the gas phase

is estimated as a function of the density.

\\ ( http://arXiv.org/abs/cond-mat/0608246 , 52kb)

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Paper: cond-mat/0608247

Date: Thu, 10 Aug 2006 16:14:44 GMT (276kb)

Title: Fluctuation statistics of mesoscopic Bose-Einstein condensate:

reconciling the master equation with the partition function to revisit the

Uhlenbeck-Einstein dilemma

Authors: Andrew N. Jordan, C. H. Raymond Ooi, Anatoly A. Svidzinsky

Comments: 13 pages, 6 figures

Subj-class: Other; Statistical Mechanics

\\

The atom fluctuations statistics of an ideal, mesoscopic, Bose-Einstein

condensate is investigated from several different perspectives. By generalizing

the grand canonical analysis (applied to the canonical ensemble problem), we

obtain a self-consistent equation for the mean condensate particle number that

coincides with the microscopic result calculated from the laser master equation

approach. For the case of a harmonic trap, we obtain an analytic expression for

the condensate particle number that is very accurate at all temperatures, when

compared with numerical canonical ensemble results. Applying a similar

generalized grand canonical treatment to the variance, we obtain an accurate

result only below the critical temperature. Analytic results are found for all

higher moments of the fluctuation distribution by employing the stochastic path

integral formalism, with excellent accuracy. We further discuss a hybrid

treatment, which weds the master equation/stochastic path integral analysis

with the results obtained based on canonical ensemble quasiparticle formalism

[V. V. Kocharovsky et al., Phys. Rev. A 61, 053606 (2000)], producing

essentially perfect agreement with numerical simulation at all temperatures.

\\ ( http://arXiv.org/abs/cond-mat/0608247 , 276kb)

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Paper: quant-ph/0608089

Date: Thu, 10 Aug 2006 07:34:34 GMT (189kb)

Title: Efficient coherent internal state transfer in trapped ions using

Stimulated Raman Adiabatic Passage

Authors: Jens L. S{\o}rensen, Ditte M{\o}ller, Theis Iversen, Jakob B. Thomsen,

Frank Jensen, Peter Staanum, Dirk Voigt, Michael Drewsen

Comments: 4 pages, 3 figures

\\

We demonstrate experimentally how the process of Stimulated Raman Adiabatic

Passage (STIRAP) can be utilized for efficient coherent internal state transfer

in single trapped and laser-cooled $^{40}$Ca$^+$ ions. The transfer from the

D$_{3/2}$ to the D$_{5/2}$ state, is detected by a fluorescence measurement

revealing the population not transfered to the D$_{5/2}$ state. A coherent

population transfer efficiency at the level of 95 % in a setup allowing for the

internal state detection of individual ions in a string has been obtained.

\\ ( http://arXiv.org/abs/quant-ph/0608089 , 189kb)

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\\

Paper: cond-mat/0608250

Date: Thu, 10 Aug 2006 20:06:59 GMT (28kb)

Title: Quantum fluids of self-assembled chains of polar molecules

Authors: Daw-Wei Wang, Mikhail D. Lukin, and Eugene Demler

Comments: 5 pages and 3 figures

Subj-class: Other; Soft Condensed Matter

\\

We study polar molecules in a stack of strongly confined pancake traps. When

dipolar moments point perpendicular to the planes of the traps and are

sufficiently strong, the system is stable against collapse but attractive

interaction between molecules in different layers leads to the formation of

extended chains of molecules, analogously to the chaining phenomenon in

classical rheological electro- and magnetofluids. We analyze properties of the

resulting quantum liquid of dipolar chains and show that only the longest

chains undergo Bose-Einstein condensation with a strongly reduced condensation

temperature. We discuss several experimental methods for studying chains of

dipolar molecules.

\\ ( http://arXiv.org/abs/cond-mat/0608250 , 28kb)

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Paper: cond-mat/0608255

Date: Fri, 11 Aug 2006 18:59:50 GMT (261kb)

Title: FFLO Vortex Lattice States in Cold Fermionic-Atom Systems

Authors: Y.-P. Shim, R. A. Duine, and A. H. MacDonald

Comments: 10 pages, 9 figures

Subj-class: Statistical Mechanics

\\

Condensation of atom pairs with finite total momentum is expected in a

portion of the phase diagram of a two-component fermionic cold-atom system.

This unusual condensate can be identified by detecting the exotic higher Landau

level (HLL) vortex lattice states it can form when rotated. With this

motivation, we have solved the linearized gap equations of a polarized cold

atom system in a Landau level basis to predict experimental circumstances under

which HLL vortex lattice states occur.

\\ ( http://arXiv.org/abs/cond-mat/0608255 , 261kb)

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Paper: cond-mat/0608258

Date: Fri, 11 Aug 2006 04:08:43 GMT (151kb)

Title: Vortex Properties of a Resonant Superfluid

Authors: Meng Gao, Hongyu Wu, Lan Yin

Comments: 13 pages, 10 figures

Subj-class: Other

Journal-ref: Phys. Rev. A 74, 023604 (2006)

\\

The properties of a vortex in a rotating superfluid Fermi gas are studied in

the unitary limit. A phenomenological approach based on Ginzburg-Landau theory

is developed for this purpose. The density profiles, including those of the

normal fluid and superfluid, are obtained at various temperatures and rotation

frequencies. The superfluid and normal fluid densities can be identified from

the angular momentum density. The total free energy and angular momentum of the

vortex are also obtained.

\\ ( http://arXiv.org/abs/cond-mat/0608258 , 151kb)

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Paper: cond-mat/0608262

Date: Fri, 11 Aug 2006 11:52:55 GMT (123kb)

Title: Quantum Phase Transition in Ultracold 87Rb Atom Gas with Radiant Field

Authors: Gang Chen, J.-Q. Liang, W.-M. Liu

Comments: 3 figures

Subj-class: Strongly Correlated Electrons

\\

A second-order quantum phase transition in two-species Bose-Einstein

condensates of 87Rb atoms coupled by a quantized radiant field is revealed

explicitly in terms of the energy spectrum which is obtained in the

thermodynamic limit and is controllable by the coupling parameter between the

atom and field. The scaling behavior of the collective excitation modes at the

critical transition point is seen to be in the same universality class as that

of the Dicke model. It is also demonstrated that the quantum phase transition

is realizable below the critical temperature of BEC and can be detected

experimentally by measuring the abrupt change of atom population imbalance.

\\ ( http://arXiv.org/abs/cond-mat/0608262 , 123kb)

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Paper: cond-mat/0608265

Date: Fri, 11 Aug 2006 12:51:53 GMT (14kb)

Title: 1/N-Expansion and the Dilute Bose Gas Beyond Mean-field Theory

Authors: Jens O. Andersen

Comments: 6 pages, 3 figs

Subj-class: Other

\\

We consider the nonrelativistic interacting Bose gas at zero and finite

temperature. Using the 1/N-expansion, we derive expressions for the free energy

density and the number density to next-to-leading order in 1/N. Outside the

critical region and at weak coupling, our calculations reduce to the well-known

mean-field results for the dilute Bose gas. We also rederive the

nonperturbative critical density for Bose condensation which was first

calculated by Baym, Blaizot, Holzmann, Lal\"oe, and Vautherin.

\\ ( http://arXiv.org/abs/cond-mat/0608265 , 14kb)

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Paper: cond-mat/0608282

Date: Fri, 11 Aug 2006 18:59:01 GMT (395kb)

Title: Thermodynamics of the BCS-BEC crossover

Authors: R. Haussmann, W. Rantner, S. Cerrito and W. Zwerger

Comments: 27 pages, 16 figures, submitted to PRA

Subj-class: Statistical Mechanics

\\

We present a self-consistent and conserving theory for the thermodynamics of

the BCS-BEC crossover, both in the normal and superfluid phase. It is based on

the variational many-body formalism developed by Luttinger and Ward and by

DeDominicis and Martin. Truncating the exact functional for the entropy to that

obtained within a ladder approximation, the resulting self-consistent integral

equations for the normal and anomalous Green functions are solved numerically

for arbitrary coupling. The critical temperature, the equation of state and the

entropy are determined as a function of the dimensionless parameter $1/k_Fa$,

which controls the crossover from the BCS-regime of extended pairs to the

BEC-regime of tightly bound molecules. The tightly bound pairs turn out to be

described by a Popov-type approximation for a dilute, repulsive Bose-gas. The

superfluid transition in our approximation is weakly first order, in contrast

to the expected continuous transition. In spite of this problem, our results

compare well with a recent numerically exact solution of the problem at the

unitarity point.

The results allow to determine the temperature dependence of the cloud size

in a harmonic trap and the temperatures reached in an isentropic ramp of the

magnetic field across a Feshbach resonance, as studied experimentally.

\\ ( http://arXiv.org/abs/cond-mat/0608282 , 395kb)

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Paper: quant-ph/0608099

Date: Fri, 11 Aug 2006 11:58:26 GMT (38kb)

Title: Uniform semiclassical approximations of the nonlinear Schroedinger

equation by a Painleve mapping

Authors: D. Witthaut and H. J. Korsch

\\

A useful semiclassical method to calculate eigenfunctions of the Schroedinger

equation is the mapping to a well-known ordinary differential equation, as for

example Airy's equation. In this paper we generalize the mapping procedure to

the nonlinear Schroedinger equation or Gross-Pitaevskii equation describing the

macroscopic wave function of a Bose-Einstein condensate. The nonlinear

Schroedinger equation is mapped to the second Painleve equation, which is one

of the best-known differential equations with a cubic nonlinearity. A

quantization condition is derived from the connection formulae of these

functions. Comparison with numerically exact results for a harmonic trap

demonstrates the benefit of the mapping method. Finally we discuss the

influence of a shallow periodic potential on bright soliton solutions by a

mapping to a constant potential.

\\ ( http://arXiv.org/abs/quant-ph/0608099 , 38kb)

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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 Tue Aug 15 2006 - 02:11:30 EST

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