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

Date: Thu, 06 Nov 2008 21:15:48 +1000

Date: Thu, 06 Nov 2008 21:15:48 +1000

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

Hello again,

This week there were 30 new preprints and 16 replacements:

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arXiv:0810.4363

Date: Fri, 24 Oct 2008 00:29:46 GMT (342kb)

Title: Testing of spin ordering Hamiltonian with ultracold atoms in optical

lattices

Authors: G. E. Akpojotor and W. Li

Categories: cond-mat.str-el

\\

Laser cooling and trapping are now widely used in atomic physics laboratory.

Interestingly, cold atoms in optical lattices are now used in advanced research

to mimic phenomena in condensed matter physics and also as a test laboratory

for the models of these phenomena. It follows then that it is now possible and

necessary to advance the atomic physics laboratory by including the use of

ultracold atoms in optical lattices for instructional contents of phenomena in

condensed matter physics. In this paper, we have proposed how to introduce into

the atomic physics laboratory the study of quantum magnetism with cold atoms in

a double well optical lattice. In particular, we demonstrates how to compare

the theoretical parameters of a spin Hamiltonian model with those extracted

from spin ordering experiment.

\\ ( http://arxiv.org/abs/0810.4363 , 342kb)

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arXiv:0810.4398

Date: Fri, 24 Oct 2008 08:35:01 GMT (685kb)

Title: Rapidly Rotating Atomic Gases

Authors: N. R. Cooper

Categories: cond-mat.mes-hall

Comments: Submitted for publication in Advances in Physics

\\

This article reviews developments in the theory of rapidly rotating

degenerate atomic gases. The main focus is on the equilibrium properties of a

single component atomic Bose gas, which (at least at rest) forms a

Bose-Einstein condensate. Rotation leads to the formation of quantized vortices

which order into a vortex array, in close analogy with the behaviour of

superfluid helium. Under conditions of rapid rotation, when the vortex density

becomes large, atomic Bose gases offer the possibility to explore the physics

of quantized vortices in novel parameter regimes. First, there is an

interesting regime in which the vortices become sufficiently dense that their

cores -- as set by the healing length -- start to overlap. In this regime, the

theoretical description simplifies, allowing a reduction to single particle

states in the lowest Landau level. Second, one can envisage entering a regime

of very high vortex density, when the number of vortices becomes comparable to

the number of particles in the gas. In this regime, theory predicts the

appearance of a series of strongly correlated phases, which can be viewed as

{\it bosonic} versions of fractional quantum Hall states. This article

describes the equilibrium properties of rapidly rotating atomic Bose gases in

both the mean-field and the strongly correlated regimes, and related

theoretical developments for Bose gases in lattices, for multi-component Bose

gases, and for atomic Fermi gases. The current experimental situation and

outlook for the future are discussed in the light of these theoretical

developments.

\\ ( http://arxiv.org/abs/0810.4398 , 685kb)

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arXiv:0810.4399

Date: Fri, 24 Oct 2008 08:41:30 GMT (54kb)

Title: Green's Function Approach to the Bose-Hubbard Model

Authors: Matthias Ohliger, Axel Pelster

Categories: cond-mat.stat-mech

\\

We use a diagrammatic hopping expansion to calculate finite-temperature Green

functions of the Bose-Hubbard model which describes bosons in an optical

lattice. This technique allows for a summation of subsets of diagrams, so the

divergence of the Green function leads to non-perturbative results for the

boundary between the superfluid and the Mott phase for finite temperatures.

Whereas the first-order calculation reproduces the seminal mean-field result,

the second order goes beyond and shifts the phase boundary in the immediate

vicinity of the critical parameters determined by the latest high-precision

Monte-Carlo simulations of the Bose-Hubbard model. In addition, our Green's

function approach allows for calculating the excitation spectrum at finite

temperature and for determining the effective masses of particles and holes.

\\ ( http://arxiv.org/abs/0810.4399 , 54kb)

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arXiv:0810.4403

Date: Fri, 24 Oct 2008 09:03:00 GMT (633kb)

Title: Topologically trapped vortex molecules in Bose-Einstein condensates

Authors: R. Geurts, M. V. Milo\v{s}evi\'c, F. M. Peeters

Categories: cond-mat.other

Comments: 5 pages, 4 figures

\\

In a numerical experiment based on Gross-Pitaevskii formalism, we demonstrate

unique topological quantum coherence in optically trapped Bose-Einstein

condensates (BECs). Exploring the fact that vortices in rotating BEC can be

pinned by a geometric arrangement of laser beams, we show the parameter range

in which vortex-antivortex molecules or multiquantum vortices are formed as a

consequence of the optically imposed symmetry. Being low-energy states, we

discuss the conditions for spontaneous nucleation of these unique molecules and

their direct experimental observation, and provoke the potential use of the

phase print of an antivortex or a multiquantum vortex when realized in

unconventional circumstances.

\\ ( http://arxiv.org/abs/0810.4403 , 633kb)

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arXiv:0810.4411

Date: Fri, 24 Oct 2008 09:11:47 GMT (188kb)

Title: Compression as a tool to detect Bose glass in cold atoms experiments

Authors: Dominique Delande and Jakub Zakrzewski

Categories: cond-mat.dis-nn cond-mat.other

Comments: 4pp. 4figs

\\

We suggest that measuring the variation of the radius of an atomic cloud when

the harmonic tap confinement is varied make it possible to monitor the

disappearance of the insulating Mott phase of an ultracold atomic gas trapped

in a disordered optical lattice. This paves the way for an unambiguous

identification of a Bose glass phase in the system.

\\ ( http://arxiv.org/abs/0810.4411 , 188kb)

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arXiv:0810.4481

Date: Fri, 24 Oct 2008 15:10:03 GMT (388kb)

Title: Thermodynamical approaches to efficient sympathetic cooling in ultracold

Fermi-Bose atomic mixtures

Authors: Michael Brown-Hayes, Qun Wei, Carlo Presilla, Roberto Onofrio

Categories: cond-mat.supr-con cond-mat.stat-mech

Comments: 13 pages, 9 figures, higher quality figures in published version

Journal-ref: Phys. Rev. A 78, 013617 (2008)

\\

We discuss the cooling efficiency of ultracold Fermi-Bose mixtures in

species-selective traps using a thermodynamical approach. The dynamics of

evaporative cooling trajectories is analyzed in the specific case of

bichromatic optical dipole traps also taking into account the effect of partial

spatial overlap between the Fermi gas and the thermal component of the Bose

gas. We show that large trapping frequency ratios between the Fermi and the

Bose species allow for the achievement of a deeper Fermi degeneracy,

consolidating in a thermodynamic setting earlier arguments based on more

restrictive assumptions. In particular, we confirm that the minimum temperature

of the mixture is obtained at the crossover between boson and fermion heat

capacities, and that below such a temperature sympathetic cooling vanishes.

When the effect of partial overlap is taken into account, optimal sympathetic

cooing of the Fermi species may be achieved by properly tuning the relative

trapping strength of the two species in a time-dependent fashion.

Alternatively, the dimensionality of the trap in the final stage of cooling can

be changed by increasing the confinement strength, which also results in a

crossover of the heat capacities at deeper Fermi degeneracies. This technique

may be extended to Fermi-Bose degenerate mixtures in optical lattices.

\\ ( http://arxiv.org/abs/0810.4481 , 388kb)

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arXiv:0810.4500

Date: Fri, 24 Oct 2008 16:19:17 GMT (34kb)

Title: Cooling ultracold bosons in optical lattices by spectral transform

Authors: David L. Feder

Categories: cond-mat.stat-mech

Comments: 13+e pages, two embedded figures, revtex

\\

It is shown theoretically how to directly obtain the energy distribution of a

weakly interacting gas of bosons confined in an optical lattice in the

tight-binding limit. This is accomplished by adding a linear potential to a

suitably prepared lattice, and allowing the gas to evolve under the influence

of the total potential. After a prescribed time, a spectral transform is

effected where each (highly non-local) energy state is transformed into a

distinct site of the lattice, thus allowing the energy distribution to be

(non-destructively) imaged in real space. Evolving for twice the time returns

the atoms to their initial state. The results suggest efficient methods to both

measure the temperature in situ, as well as to cool atoms within the lattice:

after applying the spectral transform one simply needs to remove atoms from all

but a few lattice sites. Using exact numerical calculations, the effects of

interactions and errors in the application of the lattice are examined.

\\ ( http://arxiv.org/abs/0810.4500 , 34kb)

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arXiv:0810.4486

Date: Fri, 24 Oct 2008 15:34:34 GMT (149kb)

Title: Optical Lenses for Atomic Beams

Authors: Ole Steuernagel

Categories: quant-ph physics.optics

Comments: 10 figures

\\

Superpositions of paraxial laser beam modes to generate atom-optical lenses

based on the optical dipole force are investigated theoretically. Thin, wide,

parabolic, cylindrical and circular atom lenses with numerical apertures much

greater than those reported in the literature to date can be synthesized. This

superposition approach promises to make high quality atom beam imaging and

nano-deposition feasible.

\\ ( http://arxiv.org/abs/0810.4486 , 149kb)

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arXiv:0810.4455

Date: Fri, 24 Oct 2008 14:21:09 GMT (249kb)

Title: Collisional decoherence in trapped atom interferometer that use

non-degenerate sources

Authors: James A. Stickney, Matthew B. Squires, James Scoville, Paul Baker, and

Steven Miller

Categories: physics.atom-ph

Comments: (23 pages, 5 figures)

\\

The coherence time, and thus sensitivity, of trapped atom interferometers

that use non-degenerate gasses are limited by the collisions between the atoms.

An analytic model that describes the effects of collisions between atoms in an

interferometer is developed. It is then applied to an interferometer using a

harmonically trapped non-degenerate atomic gas that is manipulated with a

single set of standing wave laser pulses. The model is used to find the optimal

operating conditions of the interferometer and direct Monte-Carlo simulation of

the interferometer is used to verify the analytic model.

\\ ( http://arxiv.org/abs/0810.4455 , 249kb)

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arXiv:0810.4474

Date: Fri, 24 Oct 2008 14:40:05 GMT (171kb)

Title: Stochastic optimization of a cold atom experiment using a genetic

algorithm

Authors: Wolfgang Rohringer, Robert Buecker, Stephanie Manz, Thomas Betz,

Christian Koller, Martin Goebel, Aurelien Perrin, Joerg Schmiedmayer,

Thorsten Schumm

Categories: physics.atom-ph

Comments: 4 pages, 3 figures

\\

We employ an evolutionary algorithm to automatically optimize different

stages of a cold atom experiment without human intervention. This approach

closes the loop between computer based experimental control systems and

automatic real time analysis and can be applied to a wide range of experimental

situations. The genetic algorithm quickly and reliably converges to the most

performing parameter set independent of the starting population. Especially in

many-dimensional or connected parameter spaces the automatic optimization

outperforms a manual search.

\\ ( http://arxiv.org/abs/0810.4474 , 171kb)

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arXiv:0810.4729

Date: Sun, 26 Oct 2008 23:51:46 GMT (1484kb,D)

Title: Introduction to Quantum Noise, Measurement and Amplification

Authors: A. A. Clerk, M. H. Devoret, S. M. Girvin, F. Marquardt, R. J.

Schoelkopf

Categories: cond-mat.mes-hall

Comments: To be submitted to Reviews of Modern Physics; 102 pages

\\

The topic of quantum noise has become extremely timely due to the rise of

quantum information physics and the resulting interchange of ideas between the

condensed matter and AMO/quantum optics communities. This review gives a

pedagogical introduction to the physics of quantum noise and its connections to

quantum measurement and quantum amplification. After introducing quantum noise

spectra and methods for their detection, we describe the basics of weak

continuous measurements. Particular attention is given to treating the standard

quantum limit on linear amplifiers and position detectors using a general

linear-response framework. We show how this approach relates to the standard

Haus-Caves quantum limit for a bosonic amplifier known in quantum optics, and

illustrate its application for the case of electrical circuits, including

mesoscopic detectors and resonant cavity detectors.

\\ ( http://arxiv.org/abs/0810.4729 , 1484kb)

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arXiv:0810.4880

Date: Mon, 27 Oct 2008 17:24:39 GMT (28kb)

Title: Density and spin response function of a normal Fermi gas at unitarity

Authors: S. Stringari

Categories: cond-mat.stat-mech

Comments: 4 pages, 2 figures

\\

Using Landau theory of Fermi liquids we calculate the dynamic response of

both a polarized and unpolarized normal Fermi gas at zero temperature in the

strongly interacting regime of large scattering length. We show that at small

excitation energies the {\it in phase} (density) response is enhanced with

respect to the ideal gas prediction due to the increased compressibility.

Viceversa, the {\it out of phase} (spin) response is quenched as a consequence

of the tendency of the system to pair opposite spins. The long wavelength

behavior of the static structure factor is explicitly calculated. The results

are compared with the predictions in the collisional and superfluid regimes.

The emergence of a spin zero sound solution in the unpolarized normal phase is

explicitly discussed.

\\ ( http://arxiv.org/abs/0810.4880 , 28kb)

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arXiv:0810.4772

Date: Mon, 27 Oct 2008 10:00:38 GMT (308kb)

Title: Pairing in fermionic systems: A quantum information perspective

Authors: Christina V. Kraus, Michael M. Wolf, J. Ignacio Cirac, Geza Giedke

Categories: quant-ph

Comments: 23 pages, 4 figures

\\

The notion of "paired" fermions is central to important condensed matter

phenomena such as superconductivity and superfluidity. While the concept is

widely used and its physical meaning is clear there exists no systematic and

mathematical theory of pairing which would allow to unambiguously characterize

and systematically detect paired states. We propose a definition of pairing and

develop methods for its detection and quantification applicable to current

experimental setups. Pairing is shown to be a quantum correlation different

from entanglement, giving further understanding in the structure of highly

correlated quantum systems. In addition, we will show the resource character of

paired states for precision metrology, proving that the BCS states allow phase

measurements at the Heisenberg limit.

\\ ( http://arxiv.org/abs/0810.4772 , 308kb)

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arXiv:0810.4983

Date: Tue, 28 Oct 2008 06:59:27 GMT (236kb,D)

Title: Rotating Fermi gases in an anharmonic trap

Authors: Kiel Howe, Aristeu R. P. Lima, Axel Pelster

Categories: cond-mat.stat-mech

\\

Motivated by recent experiments on rotating Bose-Einstein condensates, we

investigate a rotating, polarized Fermi gas trapped in an anharmonic potential.

We apply a semiclassical expansion of the density of states in order to

determine how the thermodynamic properties depend on the rotation frequency.

The accuracy of the semiclassical approximation is tested and shown to be

sufficient for describing typical experiments. At zero temperature, rotating

the gas above a given frequency $\Omega_{\rm DO}$ leads to a `donut'-shaped

cloud which is analogous to the hole found in two-dimensional Bose-Einstein

condensates. The free expansion of the gas after suddenly turning off the trap

is considered and characterized by the time and rotation frequency dependence

of the aspect ratio. Temperature effects are also taken into account and both

low- and high-temperature expansions are presented for the relevant

thermodynamical quantities. In the high-temperature regime a virial theorem

approach is used to study the delicate interplay between rotation and

anharmonicity.

\\ ( http://arxiv.org/abs/0810.4983 , 236kb)

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arXiv:0810.5046

Date: Tue, 28 Oct 2008 14:54:47 GMT (70kb)

Title: Superfluid Bose-Fermi mixture from weak-coupling to unitarity

Authors: S. K. Adhikari and Luca Salasnich

Categories: cond-mat.other

Comments: 11 pages

\\

We investigate the zero-temperature properties of a superfluid Bose-Fermi

mixture by introducing a set of coupled Galilei-invariant nonlinear

Schr\"odinger equations valid from weak-coupling to unitarity. The Bose

dynamics is described by a Gross-Pitaevskii-type equation including

beyond-mean-field corrections possessing the correct weak-coupling and

unitarity limits. The dynamics of the two-component Fermi superfluid is

described by a density-functional equation including beyond-mean-field terms

with correct weak-coupling and unitarity limits. The present set of equations

is equivalent to the equations of generalized superfluid hydrodynamics, which

take into account also surface effects. The equations describe the mixture

properly as the Bose-Bose repulsive (positive) and Fermi-Fermi attractive

(negative) scattering lengths are varied from zero to infinity in the presence

of a Bose-Fermi interaction. The present model is tested numerically as the

Bose-Bose and Fermi-Fermi scattering lengths are varied over wide ranges

covering the weak-coupling to unitarity transition.

\\ ( http://arxiv.org/abs/0810.5046 , 70kb)

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arXiv:0810.5065

Date: Tue, 28 Oct 2008 16:01:42 GMT (26kb)

Title: Trapped fermion mixtures with unequal masses: a Bogoliubov-de Gennes

approach

Authors: M. Iskin and C. J. Williams

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

Comments: 4+ pages and 3 figures

\\

We use the Bogoliubov-de Gennes formalism to analyze the ground state phases

of harmonically trapped two-species fermion mixtures with unequal masses. In

the weakly attracting limit and around unitarity, we find that the superfluid

order parameter is spatially modulated around the trap center, and that its

global maximum occurs at a finite distance away from the trap center where the

mixture is locally unpolarized. As the attraction strength increases towards

the molecular limit, the spatial modulations gradually disappear while the

Bardeen-Cooper-Schrieffer (BCS) type nonmodulated superfluid region expands

until the entire mixture becomes locally unpolarized.

\\ ( http://arxiv.org/abs/0810.5065 , 26kb)

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arXiv:0810.5081

Date: Tue, 28 Oct 2008 16:54:22 GMT (26kb)

Title: Magnetic and Superfluid Transitions in the d=1 Spin-1 Boson Hubbard

Model

Authors: G.G. Batrouni, V.G. Rousseau, and R.T. Scalettar

Categories: cond-mat.other

\\

The interplay between magnetism and metal-insulator transitions is

fundamental to the rich physics of the single band fermion Hubbard model (FHM).

Recent progress in experiments on trapped ultra-cold atoms have made possible

the exploration of similar effects in the boson Hubbard model (BHM). This paper

reports Quantum Monte Carlo (QMC) simulations of the spin-1 BHM in the ground

state. In the case of antiferromagnetic interactions, which favor singlet

formation within the Mott insulator lobes, we present exact numerical evidence

that the superfluid-insulator phase transition is first (second) order

depending on whether the Mott lobe is even (odd). In the ferromagnetic case,

the transitions are all continuous. We obtain the phase diagram in the case of

attractive spin interactions and demonstrate the existence of the ferromagnetic

superfluid. We also compare the QMC phase diagram with a third order

perturbation calculation.

\\ ( http://arxiv.org/abs/0810.5081 , 26kb)

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arXiv:0810.4874 (*cross-listing*)

Date: Mon, 27 Oct 2008 17:44:21 GMT (27kb)

Title: On the Mathematical Theory of Superfluidity

Authors: Geoffrey L. Sewell and Walter F. Wreszinski

Categories: math-ph cond-mat.stat-mech math.MP

Comments: To be published in J. Phys. A

\\

We provide a general operator algebraic formulation of superfluidity in Bose

systems, with the aim of investigating the relationships of this phenomenon

both to off-diagonal long range order (ODLRO) and to a mathematically precise

version of Landau's picture of elementary excitations. Our principal resulta

are that ODLRO leads both to rotational superfluidity and to Goldstone

excitations, while the neo-Landau picture accounts for the translational

superfluidity of flow along a pipe. The latter picture is realised by the

Lieb-Liniger-Girardeau model. Open problems are briefly discussed.

\\ ( http://arxiv.org/abs/0810.4874 , 27kb)

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arXiv:0810.4974

Date: Tue, 28 Oct 2008 03:36:16 GMT (941kb)

Title: Reality, locality and all that: "experimental metaphysics" and the

quantum foundations

Authors: Eric G. Cavalcanti

Categories: quant-ph

Comments: PhD thesis, The University of Queensland. Awarded May 2008

\\

In recent decades there has been a resurge of interest in the foundations of

quantum theory, partly motivated by new experimental techniques, partly by the

emerging field of quantum information science. Old questions, asked since the

seminal article by Einstein, Podolsky and Rosen (EPR), are being revisited. The

work of John Bell has changed the direction of investigation by recognising

that those fundamental philosophical questions can have, after all, input from

experiment. Abner Shimony has aptly termed this new field of enquiry

"experimental metaphysics". The objective of this Thesis is to contribute to

that body of research, by formalising old concepts, proposing new ones, and

finding new results in well-studied areas. Without losing from sight that the

appeal of experimental metaphysics comes from the adjective, every major result

is followed by clear experimental proposals for quantum-atom optical setups.

\\ ( http://arxiv.org/abs/0810.4974 , 941kb)

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arXiv:0810.5061

Date: Tue, 28 Oct 2008 15:55:05 GMT (428kb)

Title: Velocity distribution measurements in atomic beams generated using laser

induced back-ablation

Authors: A. Denning, A. Booth, S. Lee, M. Ammonson, and S. D. Bergeson

Categories: physics.atom-ph

Comments: 4 pages, 3 figures

\\

We present measurements of the velocity distribution of calcium atoms in an

atomic beam generated using a dual-stage laser back-ablation apparatus.

Distributions are measured using a velocity selective Doppler time-of-flight

technique. They are Boltzmann-like with rms velocities corresponding to

temperatures above the melting point for calcium. Contrary to a recent report

in the literature, this method does not generate a sub-thermal atomic beam.

\\ ( http://arxiv.org/abs/0810.5061 , 428kb)

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arXiv:0810.5153

Date: Tue, 28 Oct 2008 22:21:19 GMT (2334kb,D)

Title: Atomic three-body loss as a dynamical three-body interaction

Authors: A. J. Daley, J. M. Taylor, S. Diehl, M. Baranov, P. Zoller

Categories: cond-mat.other

Comments: 4 pages, 4 figures

\\

We discuss how large three-body loss of atoms in an optical lattice can give

rise to effective hard-core three-body interactions. For bosons, in addition to

the usual atomic superfluid, a dimer superfluid can then be observed for

attractive two-body interactions. The non-equilibrium dynamics of preparation

and stability of these phases are studied in 1D by combining time-dependent

Density Matrix Renormalisation Group techniques with a quantum trajectories

method.

\\ ( http://arxiv.org/abs/0810.5153 , 2334kb)

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arXiv:0810.5196

Date: Wed, 29 Oct 2008 05:11:09 GMT (156kb)

Title: Dynamics and modulation of ring dark soliton in 2D Bose-Einstein

condensates with tunable interaction

Authors: Xing-Hua Hu, Xiao-Fei Zhang, Dun Zhao, Hong-Gang Luo, and W. M. Liu

Categories: cond-mat.other

Comments: 6 pages, 4 figures

\\

We investigate the dynamics and modulation of ring dark soliton in 2D

Bose-Einstein condensates with tunable interaction both analytically and

numerically. The analytic solutions of ring dark soliton are derived by using a

new transformation method. For shallow ring dark soliton, it is stable when the

ring is slightly distorted, while for large deformation of the ring, vortex

pairs appear and they demonstrate novel dynamical behaviors: the vortex pairs

will transform into dark lumplike solitons and revert to ring dark soliton

periodically. Moreover, our results show that the dynamical evolution of the

ring dark soliton can be dramatically affected by Feshbach resonance, and the

lifetime of the ring dark soliton can be largely extended which offers a useful

method for observing the ring dark soliton in future experiments.

\\ ( http://arxiv.org/abs/0810.5196 , 156kb)

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arXiv:0810.5211

Date: Wed, 29 Oct 2008 07:54:14 GMT (94kb,D)

Title: Photonic Hall effect in cold atomic clouds

Authors: Beno\^it Gr\'emaud, Dominique Delande, Olivier Sigwarth, Christian

Miniatura

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

Comments: 4 pages 4 figures

\\

On the basis of exact numerical simulations and analytical calculations, we

describe qualitatively and quantitatively the interference processes at the

origin of the photonic Hall effect for resonant Rayleigh (point-dipole)

scatterers in a magnetic field. For resonant incoming light, the induced giant

magneto-optical effects result in relative Hall currents in the percent range,

three orders of magnitude larger than with classical scatterers. This suggests

that the observation of the photonic Hall effect in cold atomic vapors is

within experimental reach.

\\ ( http://arxiv.org/abs/0810.5211 , 94kb)

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arXiv:0810.5275

Date: Wed, 29 Oct 2008 13:28:27 GMT (327kb)

Title: Vortex-lattice pinning in two-component Bose-Einstein condensates

Authors: M. P. Mink, C. Morais Smith, and R. A. Duine

Categories: cond-mat.mes-hall

\\

We investigate the vortex-lattice structure for single- and two-component

Bose-Einstein condensates in the presence of an optical lattice, which acts as

a pinning potential for the vortices. The problem is considered in the

mean-field quantum-Hall regime, which is reached when the rotation frequency

$\Omega$ of the condensate in a radially symmetric trap approaches the (radial)

trapping frequency $\omega$ and the interactions between the atoms are weak. We

determine the vortex-lattice phase diagram as a function of optical-lattice

strength and geometry. In the limit of strong pinning the vortices are always

pinned at the maxima of the optical-lattice potential, similar to the

slow-rotation case. At intermediate pinning strength, however, due to the

competition between interactions and pinning energy, a structure arises for the

two-component case where the vortices are pinned on lines of minimal potential.

\\ ( http://arxiv.org/abs/0810.5275 , 327kb)

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arXiv:0810.5448

Date: Thu, 30 Oct 2008 08:52:53 GMT (902kb)

Title: Supersolid phases of hardcore bosons on the square lattice: Correlated

hopping, next-nearest neighbor hopping and frustration

Authors: F. Mila, J. Dorier, and K.P. Schmidt

Categories: cond-mat.str-el

Comments: 20 pages, 15 figures, to be published in the proceedings of YKIS2007

conference as a special issue of Prog. Theor. Phys. Suppl

\\

We discuss the appearance of supersolid phases for interacting hardcore

bosons on the square lattice when, in addition to the standard nearest neighbor

hopping and repulsion, correlated or next-nearest neighbor hopping is present.

Having in mind dimer-based quantum magnets in a field described by effective

bosonic models of this kind, we put special emphasis on a comparison between

the different cases of relative signs of the kinetic processes, which

correspond to unfrustrated or frustrated magnetic models. In the unfrustrated

case, we compare Quantum Monte Carlo simulations with a mean-field (classical)

approach, which is shown to give qualitatively correct results. Using this

classical approach for the frustrated case, we find that the phase diagram is

generically richer than in the unfrustrated case. We also investigate in detail

the differences between standard next-nearest neighbour and correlated hopping

over the diagonal, with the conclusion that both cases are similar if

checkerboard order is present at half-filling, while a supersolid phase can be

stabilized without any adjacent solid phase only in the case of correlated

hopping.

\\ ( http://arxiv.org/abs/0810.5448 , 902kb)

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arXiv:0810.5503

Date: Thu, 30 Oct 2008 15:10:57 GMT (439kb)

Title: Determination of atomic scattering lengths from measurements of

molecular binding energies near Feshbach resonances

Authors: A. D. Lange, K. Pilch, A. Prantner, F. Ferlaino, B. Engeser, H.-C.

Naegerl, R. Grimm, and C. Chin

Categories: cond-mat.other

Comments: 6 pages, 4 figures

\\

We present an analytic model to calculate the atomic scattering length near a

Feshbach resonance from data on the molecular binding energy. Our approach

considers finite-range square-well potentials and can be applied near broad,

narrow, or even overlapping Feshbach resonances. We test our model on Cs$_2$

Feshbach molecules. We measure the binding energy using magnetic-field

modulation spectroscopy in a range where one broad and two narrow Feshbach

resonances overlap. From the data we accurately determine the Cs atomic

scattering length and the positions and widths of two particular resonances.

\\ ( http://arxiv.org/abs/0810.5503 , 439kb)

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arXiv:0810.5521

Date: Thu, 30 Oct 2008 19:08:50 GMT (1412kb,D)

Title: Reconnection Dynamics for Quantized Vortices

Authors: M. S. Paoletti, Michael E. Fisher, and D. P. Lathrop

Categories: cond-mat.stat-mech cond-mat.supr-con

Comments: 12 pages, 13 figures, submitted to Physica D special topics: Fluid

Science and Turbulence

\\

By analyzing trajectories of solid hydrogen tracers in superfluid $^4$He, we

identify tens of thousands of individual reconnection events between quantized

vortices. We characterize the dynamics by the minimum separation distance

$\delta(t)$ between the two reconnecting vortices both before and after the

events. Applying dimensional arguments, this separation has been predicted to

behave asymptotically as $\delta(t) \approx A(\kappa |t-t_0|)^{1/2}$, where

$\kappa=h/m$ is the quantum of circulation. The major finding of the

experiments and their analysis is strong support for this asymptotic form with

$\kappa$ as the dominant controlling feature, although there are significant

event to event fluctuations. At the three-parameter level the dynamics may be

about equally well-fit by two modified expressions: (a) an arbitrary power-law

expression of the form $\delta(t)=B|t-t_0|^{\alpha}$ and (b) a

correction-factor expression $\delta(t)=A(\kappa|t-t_0|)^{1/2}(1+c|t-t_0|)$. In

light of possible physical interpretations we regard the correction-factor

expression (b), which attributes the observed deviations from the predicted

asymptotic form to fluctuations in the local environment and in boundary

conditions, as best describing our experimental data. The observed dynamics

appear statistically time-reversible, which suggests that an effective

equilibrium has been established in quantum turbulence on the time scales

investigated. We discuss the impact of reconnection on velocity statistics in

quantum turbulence and, as regards classical turbulence, we argue that forms

analogous to (b) could well provide an alternative interpretation of the

observed deviations from Kolmogorov scaling exponents of the longitudinal

structure functions.

\\ ( http://arxiv.org/abs/0810.5521 , 1412kb)

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\\

arXiv:0810.5420

Date: Thu, 30 Oct 2008 15:10:47 GMT (699kb)

Title: The effect of dipole-dipole interaction for two atoms with different

couplings in non-Markovian environment

Authors: Yang Li, Jiang Zhou, and Hong Guo

Categories: quant-ph

Comments: 6 pages, 2 figures

\\

Using the nonperturbative method, we study the exact entanglement dynamics of

two two-level dipole-dipole interacting atoms coupled to a common non-Markovian

reservoir with different coupling strengths. Besides analyzing the conditions

for the existence of steady state, we find, though the dipole-dipole

interaction could destroy the stationary entanglement, that relatively strong

dipole-dipole interaction does suppress the disentanglement in the initial

period of time. These results are helpful for the practical engineering of the

entanglement in the future.

\\ ( http://arxiv.org/abs/0810.5420 , 699kb)

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\\

arXiv:0810.5427

Date: Thu, 30 Oct 2008 07:17:00 GMT (344kb)

Title: Investigation of cold Rb Rydberg atoms in a magneto-optical trap

Authors: D.B.Tretyakov, I.I.Beterov, V.M.Entin, I.I.Ryabtsev, and P.L.Chapovsky

Categories: physics.atom-ph

Comments: 9 pages, 6 figures. To appear in JETP, 2009

\\

We present our results on the experiments with cold Rb Rydberg atoms in a

magneto-optical trap (MOT). Characteristic features of our experiment were the

excitation of Rydberg atoms in a small volume within the cold atom cloud and

sorting of the measured signals and spectra over the number of registered

Rydberg atoms. We have measured the effective lifetime of the Rydberg state

37P, as well as its polarizability in a weak electric field. The results are in

good agreement with the theoretical calculations. We have shown that

localization of the small excitation volume around the zero-magnetic-field

point makes possible to increase the spectral resolution and to obtain narrow

microwave resonances in Rydberg atoms without switching off the MOT quadrupole

magnetic field. We have measured the dependence of the amplitude of the

dipole-dipole interaction resonances on the number of Rydberg atoms, which has

a linear character and agrees with the theory for weak dipole-dipole

interaction.

\\ ( http://arxiv.org/abs/0810.5427 , 344kb)

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\\

arXiv:0810.5504

Date: Thu, 30 Oct 2008 15:13:07 GMT (395kb)

Title: Gap solitons on a ring

Authors: Yaroslav V. Kartashov, Boris A. Malomed, Victor A. Vysloukh, Lluis

Torner

Categories: physics.optics

Comments: 13 pages, 4 figures, to appear in Optics Letters

\\

We introduce a new species of gap solitons (GSs) supported by an azimuthally

modulated guiding ring in defocusing cubic media. The periodicity in the

azimuthal direction strongly modifies properties and existence domains of GSs.

In addition to the fundamental solitons, we report even and twisted bound

states. The former type is found to be stable, while the twisted states are

always unstable in defocusing media.

\\ ( http://arxiv.org/abs/0810.5504 , 395kb)

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The replacements:

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\\

arXiv:0805.1408

replaced with revised version Fri, 24 Oct 2008 07:07:41 GMT (392kb,D)

Title: Solids and supersolids of three-body interacting polar molecules in an

optical lattice

Authors: Kai P. Schmidt, Julien Dorier, Andreas Laeuchli

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

Comments: 4+ pages, 4 figures, published version

Journal-ref: Phys. Rev. Lett. 101, 150405 (2008)

DOI: 10.1103/PhysRevLett.101.150405

\\ ( http://arxiv.org/abs/0805.1408 , 392kb)

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\\

arXiv:0807.2426

replaced with revised version Fri, 24 Oct 2008 14:07:31 GMT (323kb)

Title: Finite temperature coherence of the ideal Bose gas in an optical lattice

Authors: G.A. Muradyan and J.R. Anglin

Categories: cond-mat.stat-mech

\\ ( http://arxiv.org/abs/0807.2426 , 323kb)

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\\

arXiv:0806.0663

replaced with revised version Fri, 24 Oct 2008 01:35:13 GMT (390kb)

Title: Controlling atomic vapor density in paraffin-coated cells using

light-induced atomic desorption

Authors: T. Karaulanov, M. T. Graf, D. English, S. M. Rochester, Y. Rosen, K.

Tsigutkin, D. Budker, E. B. Alexandrov, M. V. Balabas, D. F. Jackson Kimball,

F. A. Narducci, S. Pustelny, V. V. Yashchuk

Categories: physics.atom-ph

Comments: 10 pages, 11 figures

\\ ( http://arxiv.org/abs/0806.0663 , 390kb)

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\\

arXiv:0806.3780

replaced with revised version Mon, 27 Oct 2008 11:25:14 GMT (170kb)

Title: Cold Fermionic Atoms in Two-Dimensional Traps -- Pairing versus Hund's

Rule

Authors: M. Rontani, J. Armstrong, Y. Yu, S. {\AA}berg, S. M. Reimann

Categories: cond-mat.mes-hall

Comments: RevTeX 4.0, 5 pages, 5 colour postscript figures

\\ ( http://arxiv.org/abs/0806.3780 , 170kb)

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\\

arXiv:0809.0706

replaced with revised version Mon, 27 Oct 2008 19:08:22 GMT (941kb)

Title: Effective Action Approach for Quantum Phase Transitions in Bosonic

Lattices

Authors: Barry Bradlyn, Francisco Ednilson A. dos Santos, Axel Pelster

Categories: cond-mat.stat-mech

Comments: Phys. Rev. A (in press)

\\ ( http://arxiv.org/abs/0809.0706 , 941kb)

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\\

arXiv:0809.1487

replaced with revised version Sat, 25 Oct 2008 08:29:33 GMT (2871kb,D)

\\

arXiv:0806.4192

replaced with revised version Mon, 27 Oct 2008 23:16:49 GMT (74kb)

Title: Theory of spin nematic to spin-Peierls quantum phase transition in

ultracold spin-1 atoms in optical lattices

Authors: Christoph M. Puetter, Michael J. Lawler, Hae-Young Kee

Categories: cond-mat.str-el

Comments: 7 pages, 4 figures

Journal-ref: Phys. Rev. B 78, 165121 (2008)

\\ ( http://arxiv.org/abs/0806.4192 , 74kb)

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Title: Dynamics and statistical mechanics of ultra-cold Bose gases using

c-field techniques

Authors: P. B. Blakie, A. S. Bradley, M. J. Davis, R. J. Ballagh, and C. W.

Gardiner

Categories: cond-mat.stat-mech cond-mat.other physics.atom-ph quant-ph

Comments: 110 pages, 32 figures. Updated to address referee comments. To appear

in Advances in Physics

\\ ( http://arxiv.org/abs/0809.1487 , 2871kb)

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\\

arXiv:0809.1259

replaced with revised version Mon, 27 Oct 2008 19:41:16 GMT (984kb)

Title: Robustness of Heisenberg-limited interferometry with balanced Fock

states

Authors: D. Meiser and M. J. Holland

Categories: quant-ph

Comments: 13 pages, 6 figures; high-resolution version can be obtained from

authors

\\ ( http://arxiv.org/abs/0809.1259 , 984kb)

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\\

arXiv:0808.1703

replaced with revised version Mon, 27 Oct 2008 20:27:30 GMT (1055kb)

Title: Raman Coupling of Zeeman Sublevels in an Alkali Bose Condensate

Authors: K. C. Wright, L. S. Leslie, and N. P. Bigelow

Categories: cond-mat.other

Comments: 12 pages, 16 figures--updated references, small changes to captions,

text

\\ ( http://arxiv.org/abs/0808.1703 , 1055kb)

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\\

arXiv:0809.1820

replaced with revised version Tue, 28 Oct 2008 18:19:39 GMT (51kb)

Title: Extended Thomas-Fermi Density Functional for the Unitary Fermi Gas

Authors: Luca Salasnich and Flavio Toigo

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

Comments: 7 pages, 3 figures, 1 table; corrected some typos; to be published in

Phys. Rev. A

\\ ( http://arxiv.org/abs/0809.1820 , 51kb)

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\\

arXiv:0802.1142

replaced with revised version Tue, 28 Oct 2008 14:47:05 GMT (549kb)

Title: Beyond mean-field dynamics of small Bose-Hubbard systems based on the

number-conserving phase space approach

Authors: F. Trimborn, D. Witthaut, and H. J. Korsch

Categories: quant-ph

Comments: Significantly enhanced and revised version (20 pages, 20 figures)

\\ ( http://arxiv.org/abs/0802.1142 , 549kb)

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\\

arXiv:0803.1116

replaced with revised version Wed, 29 Oct 2008 16:28:46 GMT (99kb)

Title: Vacancy supersolid of hard-core bosons on the square lattice

Authors: Long Dang, Massimo Boninsegni and Lode Pollet

Categories: cond-mat.stat-mech

Comments: Replaced with published version

Journal-ref: Phys. Rev. B 78, 132512 (2008)

\\ ( http://arxiv.org/abs/0803.1116 , 99kb)

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\\

arXiv:0802.0833

replaced with revised version Wed, 29 Oct 2008 07:13:03 GMT (415kb)

Title: The inherent fluctuations of the pulsed atom laser in F=2 manifold of

87Rb atoms

Authors: Lin Xia, Fan Yang, Xiaoji Zhou and Xuzong Chen

Categories: physics.atom-ph

Comments: 5 pages, 6 figures

\\ ( http://arxiv.org/abs/0802.0833 , 415kb)

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\\

arXiv:0810.4499 (*cross-listing*)

replaced with revised version Wed, 29 Oct 2008 16:44:08 GMT (698kb)

Title: Coupled Mode Equations and Gap Solitons for the 2D Gross-Pitaevsky

equation with a non-separable periodic potential

Authors: Tom\'a\v{s} Dohnal and Hannes Uecker

Categories: nlin.PS math.AP physics.optics

\\ ( http://arxiv.org/abs/0810.4499 , 698kb)

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\\

arXiv:0808.3719

replaced with revised version Thu, 30 Oct 2008 14:21:38 GMT (43kb)

Title: Radial quadrupole and scissors modes in trapped Fermi gases across the

BCS phase transition

Authors: Michael Urban

Categories: cond-mat.other

Comments: 6 pages, v2: extended description of the theoretical method

\\ ( http://arxiv.org/abs/0808.3719 , 43kb)

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\\

arXiv:0809.0449

replaced with revised version Wed, 29 Oct 2008 21:36:03 GMT (185kb)

Title: Point processes in arbitrary dimension from fermionic gases, random

matrix theory, and number theory

Authors: Salvatore Torquato, A. Scardicchio and Chase E Zachary

Categories: cond-mat.stat-mech math-ph math.MP

Comments: 40 pages, 11 figures, 1 table, iopart; corrected mislabeled section

numbers and minor typographical issues; minor text changes

\\ ( http://arxiv.org/abs/0809.0449 , 185kb)

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Till next time,

Matt.

-- ========================================================================= Dr M. J. Davis, Senior Lecturer in Physics School of Physical Sciences, email: mdavis_at_physics.uq.edu.au University of Queensland, ph : +61 7 334 69824 Brisbane, QLD 4072, fax : +61 7 336 51242 Australia. http://www.physics.uq.edu.au/people/mdavis/ ========================================================================= Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland =========================================================================Received on Mon Nov 10 2008 - 13:55:15 EST

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