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

Date: Fri, 2 Feb 2007 20:00:36 +1000 (EST)

Date: Fri, 2 Feb 2007 20:00:36 +1000 (EST)

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

Hi all,

A special treat this week: the mailing is early. Although in principle I have

been on holiday this past week, next week I really will be away from work!

There are 24 new preprints this week:

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Paper: cond-mat/0701647

Date: Fri, 26 Jan 2007 12:57:36 GMT (667kb)

Title: Vortex instability, generation of new vortices, and onset of turbulence

in superfluid 3He-B

Authors: V.B. Eltsov, A.P. Finne, R. de Graaf, R. Hanninen, J. Kopu, M.

Krusius, and R.E. Solntsev

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

Subj-class: Soft Condensed Matter; Superconductivity

\\

Vortex dynamics in superfluid 3He-B is distinguished by an abrupt transition

to turbulence which is caused by a strongly temperature dependent mutual

friction dissipation. Above 0.6 Tc dynamic processes are vortex number

conserving. At lower temperatures a vortex moving in applied flow with respect

to the container walls may become unstable, create new vortices, and start

thereby turbulence. This single-vortex instability can be monitored in a

rotating long cylinder in the temperature regime where turbulence starts. By

comparing NMR measurements to numerical calculations, we study the expansion of

newly created vortices to rectilinear lines, while the instability generates

new vortices at a low rate ~ 1 vortex/s, before turbulence sets in.

\\ ( http://arXiv.org/abs/cond-mat/0701647 , 667kb)

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Paper: cond-mat/0701649

Date: Fri, 26 Jan 2007 13:53:57 GMT (33kb)

Title: Cold Attractive Spin Polarized Fermi Lattice Gases and the Doped

Positive U Hubbard Model

Authors: Adriana Moreo and D.J. Scalapino

Categories: cond-mat.str-el cond-mat.supr-con

Comments: 4 pages, 2 figures

Subj-class: Strongly Correlated Electrons; Superconductivity

\\

Experiments on polarized fermion gases performed by trapping ultracold atoms

in optical lattices, allow the study of an attractive Hubbard model for which

the strength of the on site interaction is tuned by means of a Feshbach

resonance. Using a well-known particle-hole transformation we discuss how

results obtained for this system can be reinterpreted in the context of a doped

repulsive Hubbard model. In particular we show that the

Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state corresponds to the striped state

of the two-dimensional doped positive U Hubbard model. We then use the results

of numerical studies of the striped state to relate the periodicity of the FFLO

state to the spin polarization. We also comment on the relationship of the

$d_{x^2-y^2}$ superconducting phase of the doped 2D repulsive Hubbard model to

a d-wave spin density wave state for the attractive case.

\\ ( http://arXiv.org/abs/cond-mat/0701649 , 33kb)

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Paper: cond-mat/0701668

Date: Fri, 26 Jan 2007 18:29:37 GMT (17kb)

Title: Bose-Einstein Condensate in a Harmonic Trap Decorated with Dirac Delta

Functions

Authors: Haydar Uncu, Devrim Tarhan, Ersan Demiralp, Ozgur E. Mustecaplioglu

Categories: cond-mat.other

Comments: 6 pages, 6 figures. submitted to Physical Review A

Subj-class: Other

\\

We study Bose-Einstein condensation in a harmonic trap with a dimple

potential. We specifically consider the case of a tight and deep dimple

potential and model it by using a Dirac delta function. This allows for

simpler, explicit numerical and analytical investigations of the system.

Calculating the atomic density, chemical potential, critical temperature and

the condensate fraction, the role of the relative depth of the dimple trap with

respect to the harmonic trap on large condensate formation at enhanced

temperatures is revealed clearly.

\\ ( http://arXiv.org/abs/cond-mat/0701668 , 18kb)

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Paper: quant-ph/0701185

Date: Thu, 25 Jan 2007 21:34:14 GMT (16kb)

Title: On the normal ordering of multi-mode boson operators

Authors: Toufik Mansour, Matthias Schork

Categories: quant-ph

\\

In this article combinatorial aspects of normal ordering annihilation and

creation operators of a multi-mode boson system are discussed. The modes are

assumed to be coupled since otherwise the problem of normal ordering is reduced

to the corresponding problem of the single-mode case. To describe the normal

ordering in the multi-mode case for each mode a colour is introduced and

coloured contractions are considered. A depiction for coloured contractions via

coloured linear representations is given. In analogy to the single-mode case

associated coloured Stirling numbers are defined as coefficients appearing in

the process of normal ordering powers of the number operators. Several

properties of these coloured Stirling numbers are discussed.

\\ ( http://arXiv.org/abs/quant-ph/0701185 , 16kb)

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Paper: cond-mat/0701691

Date: Sun, 28 Jan 2007 17:20:18 GMT (141kb)

Title: Nature of Intermediate States between Superfluid and Mott insulator for

Interacting Bosons in One-dimension with a Harmonic Trapping Potential

Authors: Shijie Hu, Yuchuan Wen, Xiaoqun Wang, Yue Yu

Categories: cond-mat.str-el

Comments: 4 pages, 5 figures

Subj-class: Strongly Correlated Electrons

\\

Successive quantum transitions in an intermediate regime are shown to exist

between the superfluid and Mott insulating states for interacting bosonic atoms

in one dimension with a trapping potential. These transitions, which are caused

by the interplay of the trapping potential with the competition between the

kinetic energy and the interaction, reveal novel many-body effects as reflected

by low-lying excitation behavior, unconventional long-range correlations and an

even-odd alternating squeezing process of superfluid bosons into the Mott

insulating state. These features, most likely being generic for all dimensions

when a trapping potential is involved, are relevant for both experimental

observations and physical interpretation of the Mott insulator transition.

\\ ( http://arXiv.org/abs/cond-mat/0701691 , 141kb)

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Paper: cond-mat/0701692

Date: Sun, 28 Jan 2007 17:37:06 GMT (65kb)

Title: Spinodal decomposition in polarised Fermi superfluids

Authors: A. Lamacraft, F. M. Marchetti

Categories: cond-mat.supr-con

Comments: 5 pages, 3 eps figures

Subj-class: Superconductivity

\\

We discuss the dynamics of phase separation through the process of spinodal

decomposition in a Fermi superfluid with population imbalance. We discuss this

instability first in terms of a phenomenological Landau theory. Working within

the mean-field description at zero temperature, we then find the spinodal

region in the phase diagram of polarisation versus interaction strength, and

the spectrum of unstable modes in this region. After a quench, the spinodal

decomposition starts from the Sarma state, which is a minimum of the free

energy with respect to the order parameter at fixed density and polarisation

and a maximum at fixed chemical potentials. The possibility of observing

non-trivial domain structures in current experiments with trapped atomic gases

is discussed.

\\ ( http://arXiv.org/abs/cond-mat/0701692 , 65kb)

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Paper: cond-mat/0701695

Date: Mon, 29 Jan 2007 00:36:28 GMT (46kb)

Title: Extension of the Thomas-Fermi approximation for trapped Bose-Einstein

condensates with an arbitrary number of atoms

Authors: A. Mu\~{n}oz Mateo and V. Delgado (Univ. La Laguna)

Categories: cond-mat.other

Comments: 5 pages, 3 figures. Final version published in Phys. Rev. A

Subj-class: Other

Journal-ref: Phys. Rev. A 74, 065602 (2006)

DOI: 10.1103/PhysRevA.74.065602

\\

By incorporating the zero-point energy contribution we derive simple and

accurate extensions of the usual Thomas-Fermi (TF) expressions for the

ground-state properties of trapped Bose-Einstein condensates that remain valid

for an arbitrary number of atoms in the mean-field regime. Specifically, we

obtain approximate analytical expressions for the ground-state properties of

spherical, cigar-shaped, and disk-shaped condensates that reduce to the correct

analytical formulas in both the TF and the perturbative regimes, and remain

valid and accurate in between these two limiting cases. Mean-field quasi-1D and

-2D condensates appear as simple particular cases of our formulation. The

validity of our results is corroborated by an independent numerical computation

based on the 3D Gross-Pitaevskii equation.

\\ ( http://arXiv.org/abs/cond-mat/0701695 , 46kb)

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Paper: quant-ph/0701204

Date: Mon, 29 Jan 2007 01:36:30 GMT (15kb)

Title: Signatures for generalized macroscopic superpositions

Authors: E. G. Cavalcanti and M. D. Reid

Categories: quant-ph

Comments: 4 pages, 2 figures, some changes made

Journal-ref: Phys. Rev. Lett. 97, 170405 (2006)

DOI: 10.1103/PhysRevLett.97.170405

\\

We develop criteria sufficient to enable detection of macroscopic coherence

where there are not just two macroscopically distinct outcomes for a pointer

measurement, but rather a spread of outcomes over a macroscopic range. The

criteria provide a means to distinguish a macroscopic quantum description from

a microscopic one based on mixtures of microscopic superpositions of

pointer-measurement eigenstates. The criteria are applied to Gaussian-squeezed

and spin-entangled states.

\\ ( http://arXiv.org/abs/quant-ph/0701204 , 15kb)

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Paper: quant-ph/0701207

Date: Mon, 29 Jan 2007 10:47:59 GMT (861kb)

Title: Roughness suppression in an AC atom chip

Authors: Jean-Baptiste Trebbia (LCFIO), Carlos Leonardo Garrido (LCFIO), Alzar

Ronald Cornelussen (LCFIO), Christopher Westbrook (LCFIO), Isabelle Bouchoule

(LCFIO)

Categories: quant-ph

Proxy: ccsd hal-00127098

Journal-ref: Physical review letters (29/01/2007) 4

\\

We present a method to suppress the potential roughness of a wire-based,

magnetic atom guide: modulating the wire current at a few tens of kHz, the

potential roughness, which is proportional to the wire current, averages to

zero. Using ultra-cold $^{87}{\rm Rb}$ clouds, we show experimentally that

modulation reduces the roughness by at least of a factor five without

measurable heating or atom loss. This roughness suppression results in a

dramatic reduction of the damping of center of mass oscillations.

\\ ( http://arXiv.org/abs/quant-ph/0701207 , 861kb)

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Paper: quant-ph/0701215

Date: Mon, 29 Jan 2007 18:12:52 GMT (940kb)

Title: 'Designer atoms' for quantum metrology

Authors: C. F. Roos, M. Chwalla, K. Kim, M. Riebe, and R. Blatt

Categories: quant-ph

Journal-ref: Nature 443, 316 (2006)

DOI: 10.1038/nature05101

\\

Entanglement is recognized as a key resource for quantum computation and

quantum cryptography. For quantum metrology, the use of entangled states has

been discussed and demonstrated as a means of improving the signal-to-noise

ratio. In addition, entangled states have been used in experiments for

efficient quantum state detection and for the measurement of scattering

lengths. In quantum information processing, manipulation of individual quantum

bits allows for the tailored design of specific states that are insensitive to

the detrimental influences of an environment. Such 'decoherence-free subspaces'

protect quantum information and yield significantly enhanced coherence times.

Here we use a decoherence-free subspace with specifically designed entangled

states to demonstrate precision spectroscopy of a pair of trapped Ca+ ions; we

obtain the electric quadrupole moment, which is of use for frequency standard

applications. We find that entangled states are not only useful for enhancing

the signal-to-noise ratio in frequency measurements - a suitably designed pair

of atoms also allows clock measurements in the presence of strong technical

noise. Our technique makes explicit use of non-locality as an entanglement

property and provides an approach for 'designed' quantum metrology.

\\ ( http://arXiv.org/abs/quant-ph/0701215 , 940kb)

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Paper: physics/0701311

Date: Sat, 27 Jan 2007 16:40:11 GMT (951kb)

Title: A quantitative analysis of measures of quality in science

Authors: S. Lehmann, A. D. Jackson, and B. E. Lautrup

Categories: physics.soc-ph physics.data-an

Comments: 11 pages, 8 figures, 4 tables

Subj-class: Physics and Society; Data Analysis, Statistics and Probability

\\

Condensing the work of any academic scientist into a one-dimensional measure

of scientific quality is a difficult problem. Here, we employ Bayesian

statistics to analyze several different measures of quality. Specifically, we

determine each measure's ability to discriminate between scientific authors.

Using scaling arguments, we demonstrate that the best of these measures require

approximately 50 papers to draw conclusions regarding long term scientific

performance with usefully small statistical uncertainties. Further, the

approach described here permits the value-free (i.e., statistical) comparison

of scientists working in distinct areas of science.

\\ ( http://arXiv.org/abs/physics/0701311 , 951kb)

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Paper: cond-mat/0701739

Date: Tue, 30 Jan 2007 10:19:07 GMT (30kb)

Title: Accurate determination of the superfluid-insulator transition in the

one-dimensional Bose-Hubbard model

Authors: Jakub Zakrzewski and Dominique Delande

Categories: cond-mat.stat-mech cond-mat.other

Comments: 4pp. 3figs

Subj-class: Statistical Mechanics; Other

\\

The quantum phase transition point between the insulator and the superfluid

phase at unit filling factor of the infinite one-dimensional Bose-Hubbard model

is numerically computed with a high accuracy, better than current state of the

art calculations. The method uses the infinite system version of the time

evolving block decimation algorithm, here tested in a challenging case.

\\ ( http://arXiv.org/abs/cond-mat/0701739 , 30kb)

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Paper: cond-mat/0701744

Date: Tue, 30 Jan 2007 12:02:18 GMT (169kb)

Title: Universal thermodynamics of strongly interacting Fermi gases

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

Categories: cond-mat.str-el cond-mat.supr-con

Comments: 5 pages + 3 figures, submitted for publication

Subj-class: Strongly Correlated Electrons; Superconductivity

\\

Strongly interacting Fermi gases are of great current interest. Not only are

fermions the most common particles in the universe, but they are also thought

to have a universal thermodynamic behavior for strong interactions

\cite{heiselberg,carlson,ho}. Recent experiments on ultra-cold Fermi gases

provide an unprecedented opportunity to test universality in the laboratory

\cite{hara,thomas,partridge,stewart,luo}. In principle this allows - for

example - the interior properties of hot, dense neutron stars to be

investigated on earth. Here we carry out a detailed test of this prediction. We

analyze results from three ultra-cold fermion experiments involving two

completely distinct atomic species in different kinds of atomic trap

environments \cite{partridge,stewart,luo}. The data is compared with the

predictions of a recent strong interaction theory \cite{hldepl,hldpra}.

Excellent agreement is obtained, with no adjustable parameters. By

extrapolating to zero temperature, we show that the experimental measurements

yield a many-body parameter} $\mathbf{\beta\simeq-0.59\pm.07}$,

\textbf{describing the universal energy of strongly interacting Fermi gases.

\\ ( http://arXiv.org/abs/cond-mat/0701744 , 169kb)

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Paper: cond-mat/0701751

Date: Tue, 30 Jan 2007 14:29:41 GMT (380kb)

Title: Excitonic condensation under spin-orbit coupling and BEC-BCS crossover

Authors: Tu\u{g}rul Hakio\u{g}lu and Mehmet \c{S}ahin

Categories: cond-mat.str-el cond-mat.mes-hall

Comments: Accepted for publication by Physical Review Letters

Subj-class: Strongly Correlated Electrons; Mesoscopic Systems and Quantum Hall

Effect

\\

The condensation of electron-hole (e-h) pairs is studied at zero temperature

and in the presence of a weak spin-orbit coupling (SOC) in the inversion-layer

quantum wells. Under realistic conditions, a perturbative SOC can have

observable effects in the order parameter of the experimentally

long-searched-for excitonic condensate. Firstly, the fermion exchange symmetry

is absent for the e-h pairs indicating a counterexample to the known

classification schemes of fermion pairing. With the lack of fermion exchange,

the condensate spin has no definite parity. Additionally, the excitonic SOC

breaks the rotational symmetry yielding a complex order parameter in an

unconventional way, i.e. the phase pattern of the order parameter is a function

of the condensate density. This is manifested through finite off diagonal

components of the static spin susceptibility, suggesting a new experimental

method to confirm an excitonic condensate.

\\ ( http://arXiv.org/abs/cond-mat/0701751 , 380kb)

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Paper: cond-mat/0701752

Date: Tue, 30 Jan 2007 14:48:38 GMT (194kb)

Title: Self-bound droplet of Bose and Fermi atoms in one dimension: Collective

properties in mean-field and Tonks-Girardeau regimes

Authors: Luca Salasnich, Sadhan K. Adhikari, and Flavio Toigo

Categories: cond-mat.other cond-mat.stat-mech

Comments: 9 pages, 5 figures, to be published in Phys. Rev. A

Subj-class: Other; Statistical Mechanics

\\

We investigate a dilute mixture of bosons and spin-polarized fermions in

one-dimension. With an attractive Bose-Fermi scattering length the ground-state

is a self-bound droplet, i.e. a Bose-Fermi bright soliton where the Bose and

Fermi clouds are superimposed. We find that the quantum fluctuations stabilize

the Bose-Fermi soliton such that the one-dimensional bright soliton exists for

any finite attractive Bose-Fermi scattering length. We study density profile

and collective excitations of the atomic bright soliton showing that they

depend on the bosonic regime involved: mean-field or Tonks-Girardeau.

\\ ( http://arXiv.org/abs/cond-mat/0701752 , 194kb)

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Paper: cond-mat/0701756

Date: Tue, 30 Jan 2007 16:09:58 GMT (297kb)

Title: From Feshbach-Resonance Managed Bose-Einstein Condensates to Anisotropic

Universes: Some Applications of the Ermakov-Pinney equation with

Time-Dependent Nonlinearity

Authors: G. Herring, P.G. Kevrekidis, F. Williams, T. Christodoulakis and D.J.

Frantzeskakis

Categories: cond-mat.other

Comments: 9 pages, 4 figures

Subj-class: Other

\\

In this work we revisit the topic of two-dimensional Bose-Einstein

condensates under the influence of time-dependent magnetic confinement and

time-dependent scattering length. A moment approach reduces the examination of

moments of the wavefunction (in particular, of its width) to an Ermakov-Pinney

(EP) ordinary differential equation (ODE). We use the well-known structure of

the solutions of this nonlinear ODE to ``engineer'' trapping and interatomic

interaction conditions that lead to condensates dispersing, breathing or even

collapsing. The advantage of the approach is that it is fully tractable

analytically, in excellent agreement with our numerical observations. As an

aside, we also discuss how similar time-dependent EP equations may arise in the

description of anisotropic scalar field cosmologies.

\\ ( http://arXiv.org/abs/cond-mat/0701756 , 297kb)

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Paper: cond-mat/0701758

Date: Tue, 30 Jan 2007 16:22:22 GMT (198kb)

Title: Shiva diagrams for composite-boson many-body effects : How they work

Authors: M. Combescot and O. Betbeder-Matibet

Categories: cond-mat.stat-mech

Comments: To be published in Eur. Phys. J. B

Subj-class: Statistical Mechanics

\\

The purpose of this paper is to show how the diagrammatic expansion in

fermion exchanges of scalar products of $N$-composite-boson (``coboson'')

states can be obtained in a practical way. The hard algebra on which this

expansion is based, will be given in an independent publication.

Due to the composite nature of the particles, the scalar products of

$N$-coboson states do not reduce to a set of Kronecker symbols, as for

elementary bosons, but contain subtle exchange terms between two or more

cobosons. These terms originate from Pauli exclusion between the fermionic

components of the particles. While our many-body theory for composite bosons

leads to write these scalar products as complicated sums of products of ``Pauli

scatterings'' between \emph{two} cobosons, they in fact correspond to fermion

exchanges between any number P of quantum particles, with $2 \leq P\leq N$.

These $P$-body exchanges are nicely represented by the so-called ``Shiva

diagrams'', which are topologically different from Feynman diagrams, due to the

intrinsic many-body nature of Pauli exclusion from which they originate. These

Shiva diagrams in fact constitute the novel part of our composite-exciton

many-body theory which was up to now missing to get its full diagrammatic

representation. Using them, we can now ``see'' through diagrams the physics of

any quantity in which enters $N$ interacting excitons -- or more generally $N$

composite bosons --, with fermion exchanges included in an \emph{exact} -- and

transparent -- way.

\\ ( http://arXiv.org/abs/cond-mat/0701758 , 198kb)

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Paper (*cross-listing*): hep-th/0308095

Date: Thu, 14 Aug 2003 00:45:51 GMT (2kb)

Title: Boson-Fermion Transmutation and the Statistics of Anyons

Authors: Wung-Hong Huang

Categories: hep-th cond-mat.mes-hall cond-mat.stat-mech

Subj-class: High Energy Physics - Theory; Statistical Mechanics; Mesoscopic

Systems and Quantum Hall Effect

Journal-ref: Phys.Rev. E51 (1995) 3729

\\

It is shown that, by allowing a transmutation between a boson and a fermion,

the system with both bosons and fermions will have the statistical distribution

function of an anyon.

\\ ( http://arXiv.org/abs/hep-th/0308095 , 2kb)

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Paper: cond-mat/0701761

Date: Tue, 30 Jan 2007 21:00:30 GMT (37kb)

Title: Competition between Vortex Unbinding and Tunneling in an Optical Lattice

Authors: M. A. Cazalilla, A. Iucci, and T. Giamarchi

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

Comments: 4+ pages, 1 figure

Subj-class: Statistical Mechanics; Strongly Correlated Electrons

\\

We study a system of two-dimensional Bose gases trapped in minima of a deep

one-dimensional optical lattice potential. Increasing the tunneling amplitude

between adjacent gases drives a deconfinement transition to a phase where

coherence is established between neighboring two-dimensional gases. We compute

the signature of this transition in the interference pattern of the system as

well as in its rotational response, which provides a direct measurement of the

superfluidity in the system.

\\ ( http://arXiv.org/abs/cond-mat/0701761 , 37kb)

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Paper: cond-mat/0701764

Date: Wed, 31 Jan 2007 02:28:02 GMT (53kb)

Title: Ground-state properties of trapped Bose-Einstein condensates. Extension

of the Thomas-Fermi approximation

Authors: A. Mu\~{n}oz Mateo and V. Delgado (Univ. La Laguna)

Categories: cond-mat.other

Comments: 8 pages, 6 figures. This paper generalizes our previous work

cond-mat/0701695

Subj-class: Other

\\

We derive general approximate formulas that provide with remarkable accuracy

the ground-state properties of any mean-field scalar Bose-Einstein condensate

with short-range repulsive interatomic interactions, confined in arbitrary

cylindrically symmetric harmonic traps. Our formulation is even applicable for

condensates containing a multiply quantized axisymmetric vortex. We have

checked the validity of our formulas by numerically solving the 3D

Gross-Pitaevskii equation.

\\ ( http://arXiv.org/abs/cond-mat/0701764 , 53kb)

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Paper: cond-mat/0701786

Date: Wed, 31 Jan 2007 20:36:49 GMT (69kb)

Title: Thermodynamics of a Trapped Unitary Fermi Gas

Authors: Aurel Bulgac, Joaquin E. Drut, Piotr Magierski

Categories: cond-mat.stat-mech

Comments: 4 pages, 4 figures

Subj-class: Statistical Mechanics

\\

We present the first model-independent comparison of recent measurements of

the entropy and of the critical temperature of a unitary Fermi gas, performed

by the Duke group, with the most complete results currently available from

finite temperature Monte Carlo calculations. The measurement of the critical

temperature in a cold fermionic atomic cloud is consistent with a value

$T_c=0.23(2)epsilon_F$ in the bulk, as predicted by the present authors in

their Monte Carlo calculations.

\\ ( http://arXiv.org/abs/cond-mat/0701786 , 69kb)

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Paper: quant-ph/0701221

Date: Mon, 29 Jan 2007 21:08:12 GMT (455kb)

Title: Entanglement in continuous variable systems: Recent advances and current

perspectives

Authors: Gerardo Adesso (University of Salerno), Fabrizio Illuminati

(University of Salerno)

Categories: quant-ph cond-mat.stat-mech hep-th math-ph math.MP physics.optics

Comments: 61 pages, 7 figures, 3 tables

Subj-class: Quantum Physics; Mathematical Physics; Statistical Mechanics;

Optics

\\

We review the theory of continuous-variable entanglement with special

emphasis on foundational aspects, conceptual structures, and mathematical

methods. Much attention is devoted to the discussion of separability criteria

and entanglement properties of Gaussian states, for their great practical

relevance in applications to quantum optics and quantum information, as well as

for the very clean framework that they allow for the study of the structure of

nonlocal correlations. We give a self-contained introduction to phase-space and

symplectic methods in the study of Gaussian states of infinite-dimensional

bosonic systems. We review the most important results on the separability and

distillability of Gaussian states and discuss the main properties of bipartite

entanglement. These include the extremal entanglement, minimal and maximal, of

two-mode mixed Gaussian states, the ordering of two-mode Gaussian states

according to different measures of entanglement, the unitary (reversible)

localization, and the scaling of bipartite entanglement in multimode Gaussian

states. We then discuss recent advances in the understanding of entanglement

sharing in multimode Gaussian states, including the proof of the monogamy

inequality of distributed entanglement for all Gaussian states, and its

consequences for the characterization of multipartite entanglement. We finally

review recent advances and discuss possible perspectives on the qualification

and quantification of entanglement in non Gaussian states, a field of research

that is to a large extent yet to be explored.

\\ ( http://arXiv.org/abs/quant-ph/0701221 , 455kb)

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Paper: cond-mat/0702002

Date: Wed, 31 Jan 2007 22:30:10 GMT (855kb)

Title: Mixtures of Bose gases under rotation

Authors: S. Bargi, J. Christensson, G. M. Kavoulakis, and S. M. Reimann (LTH,

Lund)

Categories: cond-mat.mes-hall

Comments: 4 pages, RevTex, 6 figures

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\

We examine the rotational properties of a mixture of two Bose gases.

Considering the limit of weak interactions between the atoms, we investigate

the behavior of the system under a fixed angular momentum. We demonstrate a

number of exact results in this many-body system.

\\ ( http://arXiv.org/abs/cond-mat/0702002 , 855kb)

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Paper: cond-mat/0702004

Date: Thu, 1 Feb 2007 11:06:41 GMT (421kb)

Title: Negative magnetic susceptibility and nonequivalent ensembles for the

mean-field $\phi^4$ spin model

Authors: A. Campa, S. Ruffo, H. Touchette

Categories: cond-mat.stat-mech

Comments: 14 pages, 4 figures, 2 appendices, REVTeX4

Subj-class: Statistical Mechanics

\\

We calculate the thermodynamic entropy of the mean-field $\phi^4$ spin model

in the microcanonical ensemble as a function of the energy and magnetization of

the model. The entropy and its derivative are obtained from the theory of large

deviations, as well as from Rugh's microcanonical formalism, which is

implemented by computing averages of suitable observables in microcanonical

molecular dynamics simulations. Our main finding is that the entropy is a

concave function of the energy for all values of the magnetization, but is

nonconcave as a function of the magnetization for some values of the energy.

This last property implies that the magnetic susceptibility of the model can be

negative when calculated microcanonically for fixed values of the energy and

magnetization. This provides a magnetization analog of negative heat

capacities, which are well-known to be associated in general with the

nonequivalence of the microcanonical and canonical ensembles. Here, the two

ensembles that are nonequivalent are the microcanonical ensemble in which the

energy and magnetization are held fixed and the canonical ensemble in which the

energy and magnetization are fixed only on average by fixing the temperature

and magnetic field.

\\ ( http://arXiv.org/abs/cond-mat/0702004 , 421kb)

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Paper: quant-ph/0702002

Date: Wed, 31 Jan 2007 22:10:46 GMT (300kb)

Title: Preparation and probing of the ground state coherence in Rubidium

Authors: Martin Oberst, Frank Vewinger, A. I. Lvovsky

Categories: quant-ph

\\

We demonstrate the preparation and probing of the coherence between the

hyperfine ground states |5S_{1/2}, F=1> and |5S_{1/2}, F=2> of the Rubidium 87

isotope. The effect of various coherence control techniques, i.e. fractional

Stimulated Raman Adiabatic Passage and Coherent Population Return on the

coherence are investigated. These techniques are implemented using nearly

degenerate pump and Stokes lasers at 795nm (Rubidium D1 transition) which

couple the two hyperfine ground states via the excited state |5P_{1/2}, F=1>

through a resonant two-photon process, in which a coherent superposition of the

two hyperfine ground states is established. The medium is probed by an

additional weak laser, which generates a four-wave mixing signal proportional

to the ground state coherence, and allows us to monitor its evolution in time.

The experimental data are compared with numerical simulations.

\\ ( http://arXiv.org/abs/quant-ph/0702002 , 300kb)

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The replacements:

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Paper: cond-mat/0701506

replaced with revised version Fri, 26 Jan 2007 06:15:15 GMT (15kb)

Title: Fractional Spin Hall Effect in Bosonic Atomic Gas

Authors: Xiong-Jun Liu, Xin Liu, L. C. Kwek and C. H. Oh

Categories: cond-mat.mes-hall

Comments: 5 pages, 1 figure

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\ ( http://arXiv.org/abs/cond-mat/0701506 , 15kb)

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Paper: quant-ph/0605231

replaced with revised version Fri, 26 Jan 2007 13:34:24 GMT (137kb)

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

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

Comments: 13 pages, 5 figures

Journal-ref: Phys. Rev. A 74, 053814 (2006)

\\ ( http://arXiv.org/abs/quant-ph/0605231 , 137kb)

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Paper: cond-mat/0609219

replaced with revised version Mon, 29 Jan 2007 12:14:29 GMT (46kb)

Title: Ground-state Competition of Two-Component Bosons in Optical Lattice near

a Feshbach Resonance

Authors: Liping Guo, Yunbo Zhang, Shu Chen

Categories: cond-mat.other

Comments: Final version in PRA

Subj-class: Other

Journal-ref: Phys. Rev. A75, 013622(6) (2007)

DOI: 10.1103/PhysRevA.75.013622

\\ ( http://arXiv.org/abs/cond-mat/0609219 , 46kb)

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Paper: cond-mat/0610623

replaced with revised version Mon, 29 Jan 2007 15:22:48 GMT (31kb)

Title: A number-conserving approach to a minimal self-consistent treatment of

condensate and non-condensate dynamics in a degenerate Bose gas

Authors: S. A. Gardiner and S.A. Morgan

Categories: cond-mat.other

Comments: 20 pages, revised in response to referee's comments. Submitted to

Phys. Rev. A

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0610623 , 31kb)

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Paper: cond-mat/0611450

replaced with revised version Mon, 29 Jan 2007 09:49:52 GMT (16kb)

Title: Bethe Ansatz for 1D interacting anyons

Authors: M.T. Batchelor, X.-W. Guan and J.-S. He

Categories: cond-mat.stat-mech

Comments: 22 pages, two references added, small improvements to text

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0611450 , 16kb)

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Paper: cond-mat/0612670

replaced with revised version Mon, 29 Jan 2007 06:35:16 GMT (28kb)

Title: Anderson Localization of Expanding Bose-Einstein Condensates in Random

Potentials

Authors: Laurent Sanchez-Palencia (LCFIO), David Cl\'{e}ment (LCFIO), Pierre

Lugan (LCFIO), Philippe Bouyer (LCFIO), Georgy V. Shlyapnikov (LPTMS), Alain

Aspect (LCFIO)

Categories: cond-mat.other

Comments: 4 pages, 2 figures; misprint corrected

Proxy: ccsd hal-00122278

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0612670 , 28kb)

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Paper: cond-mat/0603106

replaced with revised version Thu, 1 Feb 2007 14:43:45 GMT (101kb)

Title: Partially suppressed long-range order in the Bose-Einstein condensation

of polaritons

Authors: Davide Sarchi, Vincenzo Savona

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

Subj-class: Materials Science; Mesoscopic Systems and Quantum Hall Effect;

Other

\\ ( http://arXiv.org/abs/cond-mat/0603106 , 101kb)

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Paper: cond-mat/0606216

replaced with revised version Thu, 1 Feb 2007 16:38:34 GMT (462kb)

Title: The Mott insulator transition in two dimensions

Authors: I. B. Spielman, W. D. Phillips, and J. V. Porto

Categories: cond-mat.other

Comments: Expanded version of text accepted for publication in PRL. Changes:

significant textual improvement, and corrected numerical transcription errors

relevant to Figs 1. and 4

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0606216 , 462kb)

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Paper: cond-mat/0606471

replaced with revised version Thu, 1 Feb 2007 08:53:07 GMT (45kb)

Title: Studies of bosons in optical lattices in a harmonic potential

Authors: R. Ramakumar, A. N. Das, and S. Sil

Categories: cond-mat.stat-mech cond-mat.other

Comments: Revised version, References updated, a new section on Fermions added,

14 pages, 16 figures

Subj-class: Statistical Mechanics; Other

\\ ( http://arXiv.org/abs/cond-mat/0606471 , 45kb)

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Paper: cond-mat/0701751

replaced with revised version Thu, 1 Feb 2007 15:44:30 GMT (380kb)

Title: Excitonic condensation under spin-orbit coupling and BEC-BCS crossover

Authors: Tu\u{g}rul Hakio\u{g}lu and Mehmet \c{S}ahin

Categories: cond-mat.str-el cond-mat.mes-hall

Comments: Accepted for publication by Physical Review Letters

Subj-class: Strongly Correlated Electrons; Mesoscopic Systems and Quantum Hall

Effect

\\ ( http://arXiv.org/abs/cond-mat/0701751 , 380kb)

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Till next time,

Matt.

-- ========================================================================= Dr M. J. Davis, Senior Lecturer in Physics School of Physical Sciences, email: mdavis_at_physics.uq.edu.au University of Queensland, ph : +61 7 334 69824 Brisbane, QLD 4072, fax : +61 7 336 51242 Australia. http://www.physics.uq.edu.au/people/mdavis/ ========================================================================= Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland =========================================================================Received on Fri Feb 02 2007 - 20:00:36 EST

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