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

Date: Tue, 26 Aug 2008 08:26:20 +1000

Date: Tue, 26 Aug 2008 08:26:20 +1000

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

Hi everyone,

A combination of illness and lectures have meant that I've fallen well behind.

In the last week of July there were 28 new preprints and 6 replacements.

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arXiv:0807.3989

Date: Fri, 25 Jul 2008 02:40:20 GMT (97kb)

Title: Localized gap soliton trains of Bose-Einstein condensates in an optical

lattice

Authors: D. L. Wang, X. H. Yan, W. M. Liu

Categories: cond-mat.other

Comments: 9 pages, 6 figures, accepted for publicaiton in PRE

\\

We develop a systematic analytical approach to study the linear and nonlinear

solitary excitations of quasi-one-dimensional Bose-Einstein condensates trapped

in an optical lattice. For the linear case, the Bloch wave in the $nth$ energy

band is a linear superposition of Mathieu's functions $ce_{n-1}$ and $se_n$;

and the Bloch wave in the $nth$ band gap is a linear superposition of $ce_n$

and $se_n$. For the nonlinear case, only solitons inside the band gaps are

likely to be generated and there are two types of solitons -- fundamental

solitons (which is a localized and stable state) and sub-fundamental solitons

(which is a lacalized but unstable state). In addition, we find that the

pinning position and the amplitude of the fundamental soliton in the lattice

can be controlled by adjusting both the lattice depth and spacing. Our

numerical results on fundamental solitons are in quantitative agreement with

those of the experimental observation [Phys. Rev. Lett. {\bf92}, 230401

(2004)]. Furthermore, we predict that a localized gap soliton train consisting

of several fundamental solitons can be realized by increasing the length of the

condensate in currently experimental conditions.

\\ ( http://arxiv.org/abs/0807.3989 , 97kb)

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arXiv:0807.4066

Date: Fri, 25 Jul 2008 11:29:14 GMT (26kb)

Title: Geometric potentials in quantum optics: A semi-classical interpretation

Authors: Marc Cheneau (LKB - Lhomond), Steffen Patrick Rath (LKB - Lhomond),

Tarik Yefsah (LKB - Lhomond), Kenneth John G\"unter (LKB - Lhomond),

Gediminas Juzeliunas, Jean Dalibard (LKB - Lhomond)

Categories: cond-mat.other

Comments: 6 pages 1 figure

\\

We propose a semi-classical interpretation of the geometric scalar and vector

potentials that arise due to Berry's phase when an atom moves slowly in a light

field. Starting from the full quantum Hamiltonian, we turn to a classical

description of the atomic centre-of-mass motion while still treating the

internal degrees of freedom as quantum variables. We show that the scalar

potential can be identified as the kinetic energy of an atomic micro-motion

caused by quantum fluctuations of the radiative force, and that the

Lorentz-type force appears as a result of the motion-induced perturbation of

the internal atomic state. For a specific configuration involving two

counter-propagating Gaussian laser beams, we relate the geometric forces to the

radiation pressure and dipole forces known from quantum optics. The simple

physical pictures provided by the present analysis may help for the design and

the implementation of novel geometric forces.

\\ ( http://arxiv.org/abs/0807.4066 , 26kb)

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arXiv:0807.4142

Date: Fri, 25 Jul 2008 16:50:26 GMT (50kb)

Title: Gutzwiller approach to the Bose-Hubbard model with random local

impurities

Authors: P. Buonsante, F. Massel, V. Penna and A. Vezzani

Categories: cond-mat.dis-nn

Comments: 12 pages, 5 figures

\\

Recently it has been suggested that fermions whose hopping amplitude is

quenched to extremely low values provide a convenient source of local disorder

of lattice bosonic systems realized in current experiment on ultracold atoms.

Here we investigate the phase diagram of such systems, which provide the

experimental realization of a Bose-Hubbard model whose local potentials are

randomly extracted from a binary distribution. We adopt a site-dependent

Gutzwiller description of the state of the system, and obtain results agreeing

with previous findings, as far as the compressibility of the system is

concerned. We discuss the expected peaks in the experimental excitation

spectrum of the system, related to the incompressible phases, and the

superfluid character of the {\it partially compressible phases} characterizing

the phase diagram of systems with binary disorder. In our investigation we make

use of several analytical results whose derivation is described in the

appendices, and whose validity is not limited to the system under concern.

\\ ( http://arxiv.org/abs/0807.4142 , 50kb)

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arXiv:0807.4100

Date: Fri, 25 Jul 2008 13:40:08 GMT (432kb)

Title: Magneto optical trapping of Barium

Authors: S. De, U. Dammalapati, K. Jungmann, L. Willmann

Categories: physics.atom-ph

Comments: 4 pages, 5 figures

\\

First laser cooling and trapping of the heavy alkaline earth element barium

has been achieved based on the strong 6s$^2$ $^1$S$_0$ - 6s6p $^1$P$_1$

transition for the main cooling. Due to the large branching into metastable

D-states several additional laser driven transitions are required to provide a

closed cooling cycle. A total efficiency of $0.4(1) \cdot 10^{-2}$ for slowing

a thermal atomic beam and capturing atoms into a magneto optical trap was

obtained. Trapping lifetimes of more than 1.5 s were observed. This lifetime is

shortened at high laser intensities by photo ionization losses. The developed

techniques will allow to extend significantly the number of elements that can

be optically cooled and trapped.

\\ ( http://arxiv.org/abs/0807.4100 , 432kb)

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arXiv:0807.4022 (*cross-listing*)

Date: Fri, 25 Jul 2008 08:29:56 GMT (1380kb,D)

Title: Stark deceleration of OH radicals in low-field-seeking and

high-field-seeking quantum states

Authors: Kirstin Wohlfart, Frank Filsinger, Fabian Gr\"atz, Jochen K\"upper,

Gerard Meijer

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

Comments: 8 pages, 9 figures

\\

The Stark deceleration of OH radicals in both low-field-seeking and

high-field-seeking levels of the rovibronic ${}^2\Pi_{3/2},v=0,J=3/2$ ground

state is demonstrated using a single experimental setup. Applying

alternating-gradient focusing, OH radicals in their low-field-seeking

${}^2\Pi_{3/2},v=0,J=3/2,f$ state have been decelerated from 345 m/s to 239

m/s, removing 50 % of the kinetic energy using only 27 deceleration stages. The

alternating-gradient decelerator allows to independently control longitudinal

and transverse manipulation of the molecules. Optimized high-voltage switching

sequences for the alternating-gradient deceleration are applied, in order to

adjust the dynamic focusing strength in every deceleration stage to the

changing velocity over the deceleration process. In addition we have also

decelerated OH radicals in their high-field-seeking ${}^2\Pi_{3/2},v=0,J=3/2,e$

state from 355 m/s to 316 m/s. For the states involved, a real crossing of

hyperfine levels occurs at 640 V/cm, which is examined by varying a bias

voltage applied to the electrodes.

\\ ( http://arxiv.org/abs/0807.4022 , 1380kb)

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arXiv:0807.4185

Date: Fri, 25 Jul 2008 20:39:00 GMT (11kb)

Title: Critical properties of 1D spin-gapped fermions at the onset of

magnetization

Authors: T. Vekua, S.I. Matveenko, and G.V. Shlyapnikov

Categories: cond-mat.str-el

Comments: 4 revtex pages

\\

We develop an effective field theory for finding critical properties of 1D

spin gapped fermions at the onset of magnetization. It is shown how the

spin-charge interaction leads to a linear critical behavior and finite

susceptibility for a wide range of models. We also discuss possible

manifestations of spin-charge coupling in cold atomic gases.

\\ ( http://arxiv.org/abs/0807.4185 , 11kb)

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arXiv:0807.4245

Date: Sat, 26 Jul 2008 21:27:11 GMT (78kb)

Title: Dirac-point engineering and topological phase transitions in honeycomb

optical lattices

Authors: B. Wunsch, F. Guinea, F. Sols

Categories: cond-mat.mes-hall

Comments: 10 pages, 5 figures

\\

We study the electronic structure and the phase diagram of non-interacting

fermions confined to hexagonal optical lattices. In the first part, we compare

the properties of Dirac points arising in the eigenspectrum of either honeycomb

or triangular lattices. Numerical results are complemented by analytical

equations for weak and strong confinements. In the second part we discuss the

phase diagram and the evolution of Dirac points in honeycomb lattices applying

a tight-binding description with arbitrary nearest-neighbor hoppings. With

increasing asymmetry between the hoppings the Dirac points approach each other.

At a critical asymmetry the Dirac points merge to open an energy gap, thus

changing the topology of the eigenspectrum. We analyze the trajectory of the

Dirac points and study the density of states in the different phases.

Manifestations of the phase transition in the temperature dependence of the

specific heat and in the structure factor are discussed.

\\ ( http://arxiv.org/abs/0807.4245 , 78kb)

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arXiv:0807.4434

Date: Mon, 28 Jul 2008 12:39:06 GMT (120kb)

Title: Phase separation in imbalanced fermion superfluids beyond mean-field

Authors: J. Tempere, S.N. Klimin, J.T. Devreese

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

Comments: 10 pages, 3 figures

\\

The density distributions of the two components of a trapped, ultracold Fermi

gas with population imbalance reveal the effect of imbalance on superfluid

pairing. We develop a path-integral derivation of the density, that takes into

account both fluctuations beyond mean-field and effects of nonzero temperature.

The calculated density profiles compare favorably to the measured density

profiles, and illustrate the necessity to incorporate both quantum fluctuations

and finite temperature effects. The temperature dependence of the density

profiles, especially near the superfluid-normal interface, allows determining

the temperature of the superfluid core in current experiments.

\\ ( http://arxiv.org/abs/0807.4434 , 120kb)

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arXiv:0807.4504

Date: Mon, 28 Jul 2008 17:32:34 GMT (979kb)

Title: Role of interactions in 87Rb-40K Bose-Fermi mixtures in a 3d optical

lattice

Authors: Th. Best, S. Will, U. Schneider, L. Hackermueller, D.-S. Luehmann, D.

van Oosten, and I. Bloch

Categories: cond-mat.other

Comments: 5 pages, 4 figures

\\

We investigate the effect of interspecies interaction on a degenerate mixture

of bosonic 87Rb and fermionic 40K atoms in a three-dimensional optical lattice

potential. Using a Feshbach resonance, the 87Rb-40K interaction is tuned over a

wide range. Through an analysis of the 87Rb momentum distribution, we find a

pronounced asymmetry between strong repulsion and strong attraction. In the

latter case, the Bose-Hubbard parameters are renormalized due to self-trapping,

leading to a marked shift in the superfluid to Mott insulator transition with

increasing Bose-Fermi interaction.

\\ ( http://arxiv.org/abs/0807.4504 , 979kb)

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arXiv:0807.4335

Date: Sun, 27 Jul 2008 23:19:41 GMT (125kb)

Title: Rubidium resonant squeezed light from a diode-pumped optical-parametric

oscillator

Authors: A. Predojevi\'c, Z. Zhai, J.M. Caballero, M.W. Mitchell

Categories: quant-ph

Comments: 6 pages 4 figures

\\

We demonstrate a diode-laser-pumped system for generation of quadrature

squeezing and polarization squeezing. Due to their excess phase noise, diode

lasers are challenging to use in phase-sensitive quantum optics experiments

such as quadrature squeezing. The system we present overcomes the phase noise

of the diode laser through a combination of active stabilization and

appropriate delays in the local oscillator beam. The generated light is

resonant to the rubidium D1 transition at 795nm and thus can be readily used

for quantum memory experiments.

\\ ( http://arxiv.org/abs/0807.4335 , 125kb)

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arXiv:0807.4437

Date: Mon, 28 Jul 2008 12:44:48 GMT (229kb)

Title: Detection of hidden entanglement by photon anti-bunching

Authors: Alessandro Fedrizzi, Thomas Herbst, Markus Aspelmeyer, Marco Barbieri,

Thomas Jennewein, Anton Zeilinger

Categories: quant-ph

Comments: 5 pages, 3 figures

\\

Two-photon anti-bunching at a beamsplitter is only possible if the photons

are entangled in one specific state, anti-symmetric in the modes. Thus,

detection of anti-bunching is a direct indication of entanglement in a variable

which might not be directly accessible in an experiment, since the total state

of two photons must be symmetric. We demonstrate this explicitly quantitatively

in the case of frequency entanglement of two photons with continuous frequency

detunings. The principle of detecting hidden entanglement via anti-bunching at

a beamsplitter may facilitate the observation of entanglement in other systems,

like atomic ensembles or BECs. The analogue in fermionic systems would be to

observe bunching.

\\ ( http://arxiv.org/abs/0807.4437 , 229kb)

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arXiv:0807.4440

Date: Mon, 28 Jul 2008 13:09:45 GMT (330kb)

Title: Unusual decoherence in qubit measurements with a Bose-Einstein

condensate

Authors: D. Sokolovski and S.A. Gurvitz

Categories: quant-ph

Comments: 4 pages

\\

We consider an electrostatic qubit located near a Bose-Einstein condensate

(BEC) of noninteracting bosons in a double-well potential, which is used for

qubit measurements. Tracing out the BEC variables we obtain a simple analytical

expression for the qubit's density-matrix. The qubit's evolution exhibits a

slow ($\propto1/\sqrt{t}$) damping of the qubit's coherence term, in contrast

to the exponential damping produced by most classical detectors. The

decoherence is, in general, incomplete and strongly depends on the initial

state of the qubit. In the special case of a static qubit the suppression of

the coherence term is shown to be Gaussian in time.

\\ ( http://arxiv.org/abs/0807.4440 , 330kb)

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arXiv:0807.4397

Date: Mon, 28 Jul 2008 10:35:07 GMT (73kb)

Title: High-Precision Measurement of the Laser-Trapping Frequencies for

$^{209,210,211}$Fr Atoms

Authors: S. Sanguinetti, R. Calabrese, L. Corradi, A. Dainelli, A. Khanbekyan,

E. Mariotti, C. de Mauro, P. Minguzzi, L. Moi, G. Stancari, L. Tomassetti, S.

Veronesi

Categories: physics.atom-ph

Comments: 4 pages, 2 figures, 1 table

\\

We present the accurate measurement of the frequency of the $7S-7P$

laser-trapping transition for three francium isotopes. Our approach is based on

an interferometric comparison to deduce the unknown laser frequency from a

secondary laser frequency-standard. After careful investigation of systematics,

with samples of about 100 atoms the final accuracy reaches 8 MHz, an order of

magnitude better than the best previous measurement for $^{210}$Fr, and opens

the way to improved tests of the theoretical computation of Fr atomic

structure.

\\ ( http://arxiv.org/abs/0807.4397 , 73kb)

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arXiv:0807.4534

Date: Mon, 28 Jul 2008 20:02:01 GMT (43kb)

Title: Unconventional quantum phases of lattice bosonic mixtures

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

Categories: cond-mat.other

Comments: 7 pages, 3 figures

\\

We discuss strongly interacting one-dimensional boson-boson mixtures and

study their quantum phase diagrams as the interspecies repulsion is increased.

In particular, we analyze the low-energy quantum emulsion metastable states

occurring at large values of the interspecies interaction, which are expected

to prevent the system from reaching its true ground state. A significant

decrease in the visibility of the atomic clouds is predicted as well, and

related to the trapping of the system in the spontaneously disordered quantum

emulsion states.

\\ ( http://arxiv.org/abs/0807.4534 , 43kb)

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arXiv:0807.4563

Date: Tue, 29 Jul 2008 00:43:32 GMT (781kb)

Title: Three-body Interactions in one Dimension

Authors: B. Capogrosso-Sansone, S. Wessel, H.P. B\u"chler, P. Zoller, and G.

Pupillo

Categories: cond-mat.other

Comments: 4 pages, 4 figures

\\

We determine the phase-diagram of an ensemble of hard-core lattice bosons

interacting via repulsive three-body interactions in one dimension by analytic

methods and extensive quantum Monte-Carlo simulations. Such three-body

interactions can be derived from a microscopic theory for polar molecules

trapped in an optical lattice. Depending on the strength of the interactions

and the particle density, we find superfluid and solid phases, the latter

appearing at an unconventional filling of the lattice and displaying a novel

coexistence of charge-density-wave and bond orders.

\\ ( http://arxiv.org/abs/0807.4563 , 781kb)

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arXiv:0807.4627

Date: Tue, 29 Jul 2008 10:41:00 GMT (9kb)

Title: The absence of fragmentation in Bose-Einstein condensates

Authors: A. D. Jackson, G. M. Kavoulakis, M. Magiropoulos

Categories: cond-mat.other

Comments: 4 pages

\\

A Bose-Einstein condensate produced by a Hamiltonian which is rotationally or

translationally symmetric is fragmented as a direct result of these symmetries.

A corresponding mean-field unfragmented state, with an identical energy to

leading order in the number of particles, can generally be constructed. As a

consequence, vanishingly weak symmetry-breaking perturbations destabilize the

fragmented state, which would thus be extremely difficult to realize

experimentally, and lead to an unfragmented condensate.

\\ ( http://arxiv.org/abs/0807.4627 , 9kb)

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arXiv:0807.4632

Date: Tue, 29 Jul 2008 18:47:48 GMT (138kb)

Title: Quantum Thermodynamics of Non-Ideal Gases

Authors: Antonin Coutant and S. G. Rajeev

Categories: cond-mat.stat-mech

\\

We show that when the thermal wavelength is comparable to the spatial size of

a system, thermodynamic observables like Pressure and Volume have quantum

fluctuations that cannot be ignored. They are now represented by operators;

conventional (classical) thermodynamics is no longer applicable. We continue

the work in earlier papers where quantization rules for thermodynamics were

developed by analogy with optics and mechanics, by working out explicitly the

quantum theory of van der Waals gases. We find a wave equation satisfied by the

thermodynamic wave function as well as solutions ({\em coherent states}) that

are centered at the classical equations of state. The probability of departure

from the classical theory is dependent on a parameter $\sigma$ which is a

property of the gas molecule.

\\ ( http://arxiv.org/abs/0807.4632 , 138kb)

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arXiv:0807.4724

Date: Tue, 29 Jul 2008 19:52:12 GMT (1480kb)

Title: On the dark nature of exciton Bose-Einstein condensate

Authors: Monique Combescot, Michael N. Leuenberger

Categories: cond-mat.str-el

Comments: 6 pages, 6 figures

\\

We show that for the very same reason that excitons are bright, i.e. coupled

to photons, they have a higher energy than dark excitons, even for electrons

spatially separated from holes, such as in a double quantum well. Indeed, the

same channel which produces the finite electron-hole effective overlap

responsible for the absorption and emission of photon allows for Coulomb

interband exchange processes, which are nothing but a sequence of virtual

recombination and creation of one electron-hole pair. Consequently, this

additional repulsive electron-hole Coulomb exchange interaction exists for

bright excitons, but not for dark excitons. If we now remember that dark

excitons with spins $\pm 2$ are formed in a natural way through carrier

exchange between two opposite spin bright excitons, we are led to predict that

in a double quantum well sample with one trap -- a configuration appropriate to

get high density -- exciton Bose-Einstein condensation should appear when

cooling down the sample as a dark spot made of $(\pm 2)$ excitons at the center

of the trap.

\\ ( http://arxiv.org/abs/0807.4724 , 1480kb)

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arXiv:0807.4440 (*cross-listing*)

Date: Mon, 28 Jul 2008 13:09:45 GMT (330kb)

Title: Unusual decoherence in qubit measurements with a Bose-Einstein

condensate

Authors: D. Sokolovski and S.A. Gurvitz

Categories: quant-ph cond-mat.mes-hall

Comments: 4 pages

\\

We consider an electrostatic qubit located near a Bose-Einstein condensate

(BEC) of noninteracting bosons in a double-well potential, which is used for

qubit measurements. Tracing out the BEC variables we obtain a simple analytical

expression for the qubit's density-matrix. The qubit's evolution exhibits a

slow ($\propto1/\sqrt{t}$) damping of the qubit's coherence term, in contrast

to the exponential damping produced by most classical detectors. The

decoherence is, in general, incomplete and strongly depends on the initial

state of the qubit. In the special case of a static qubit the suppression of

the coherence term is shown to be Gaussian in time.

\\ ( http://arxiv.org/abs/0807.4440 , 330kb)

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arXiv:0807.4781

Date: Wed, 30 Jul 2008 08:50:46 GMT (84kb)

Title: Towards Landau parameters of strongly interacting fermions with a

nonlinear transformation

Authors: Ji-sheng Chen

Categories: cond-mat.stat-mech

Comments: 4 pages, 2 figures

\\

A nonlinear transformation approach is formulated for the correlated fermions

thermodynamics through a medium dependent potential. With an auxiliary implicit

variable-effective chemical potential, the grand partition function is made of

coupled parametric equations. With the Sommerfeld lemma, the low temperature

expansions are performed for the adiabatic compressibility (sound speed) and

specific heat. The expressions for the Landau parameters $F_0^s$ and $F_1^s$

are obtained. As an universal constant, the effective fermion mass is

$m^*={10/9}m$. The study shows that there is a knee peak at $T^*\approx 0.21

T_f$ for the ratio of specific heat at unitarity to that of ideal Fermi gas.

This unusual behavior results from the competitive particle number density and

temperature fluctuations.

\\ ( http://arxiv.org/abs/0807.4781 , 84kb)

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arXiv:0807.4905

Date: Wed, 30 Jul 2008 18:31:34 GMT (185kb)

Title: Vortex Molecules in Spinor Condensates

Authors: Ari M. Turner and Eugene Demler

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

Comments: 28 pages, 12 figures

\\

Condensates of atoms with spins can have vortices of several types; these are

related to the symmetry group of the atoms' ground state. We discuss how, when

a condensate is placed in a small magnetic field that breaks the spin symmetry,

these vortices may form bound states. Using symmetry classification of

vortex-charge and rough estimates for vortex interactions, one can show that

some configurations that are stable at zero temperature can decay at finite

temperatures by crossing over energy barriers. Our focus is cyclic spin 2

condensates, which have tetrahedral symmetry.

\\ ( http://arxiv.org/abs/0807.4905 , 185kb)

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arXiv:0807.4762

Date: Tue, 29 Jul 2008 23:51:13 GMT (393kb)

Title: Backaction noise produced via cavity-aided nondemolition measurement of

an atomic clock state

Authors: Igor Teper, Geert Vrijsen, Jongmin Lee, and Mark A. Kasevich

Categories: quant-ph

Comments: 4.1 pages, 3 figures

\\

We use a quantum nondemolition measurement to probe the collective pseudospin

of an atomic ensemble in a high-finesse optical cavity. We analyze the

backaction antisqueezing produced by the measurement process to show that our

protocol can create conditional spin squeezing in the atomic ensemble.

\\ ( http://arxiv.org/abs/0807.4762 , 393kb)

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arXiv:0807.4980

Date: Thu, 31 Jul 2008 05:00:26 GMT (71kb)

Title: Dynamical pattern formation during growth of a dual-species

Bose-Einstein condensate

Authors: Shai Ronen, John L. Bohn, Laura E. Halmo, and Mark Edwards

Categories: cond-mat.other

\\

We simulate the growth of a dual species Bose-Einstein condensate using a

Gross-Pitaevskii equation with an additional gain term giving rise to the

growth. Such growth occurs during simultaneous evaporative cooling of a mixture

of two gases. The ground state of a dual condensate is normally either a

miscible mixture, or an immiscible phase with two spatially separated

components. In a cigar trap the ground state typically consists of one

component in the center, and the other component flanking it. Our simulations

show that when the condensates are formed in a cigar trap and the mixture is

phase separated, then the final state upon the end of the growth is generally

far from the true ground state of the system. Instead it consists of multiple,

interleaved bubbles of the two species. Such a pattern was observed recently in

an experiment by Wieman's group at JILA, and our simulations are in good

qualitative agreement with the experiment. We explain the pattern formation as

due to the onset of modulation instability during growth, and study the

dependence of the final state pattern on various parameters of the system.

\\ ( http://arxiv.org/abs/0807.4980 , 71kb)

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arXiv:0807.4990

Date: Thu, 31 Jul 2008 06:27:41 GMT (103kb)

Title: Imbalanced superfluid state in an annular disk

Authors: Fei Ye, Yan Chen, Z. D. Wang and F. C. Zhang

Categories: cond-mat.supr-con

Comments: 8 pages, 10 figures

\\

The imbalanced superfluid state with an s-wave pairing of spin-1/2 fermions

in an annular disk is numerically studied by solving the Bogoliubov-de-Gennes

equation at zero temperature. Annular disks with narrow radial width and the

one-dimensional ring are considered, where the superfluid order parameter

modulates only along the circumferential direction. The calculations are

carried out for two distinct types of systems. The first case may be relevant

to heavy fermion superconductors, where the electrons spins interact with an

external magnetic field via the Zeeman term and the system is studied in a

grand canonical ensemble. The second case may be relevant to cold fermion

atoms, where the number of fermions of each spin is fixed, and the system is

studied in a canonical ensemble. In the first case, as the magnetic field

increases, the system is transformed from a uniform superfluid state to the

Fulde-Ferrel-Larkin-Ovchinnikov state with sinusoidally modulated pairing order

parameter, and then to a spin polarized normal state. In the second case, the

ground state of the spin imbalanced system depends on the pairing strength. For

weak pairing interactions, the ground state exhibits a periodic domain wall

lattice pattern with a localized spin distribution for low spin imbalance, and

a sinusoidally modulated pattern with extended spin distribution for high spin

imbalance. For strong pairing interactions, the phase separation between

superfluid state and polarized normal state is found to be more preferable,

while the increase of spin imbalance simply extends the spatial region of the

normal state. The condition for the occurrence of Sarma state is also discussed

in this ring disk geometry.

\\ ( http://arxiv.org/abs/0807.4990 , 103kb)

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arXiv:0807.5005

Date: Thu, 31 Jul 2008 08:03:45 GMT (14kb)

Title: Asymptotic localization of stationary states in the nonlinear

Schroedinger equation

Authors: Shmuel Fishman, Alexander Iomin, and Kirone Mallick

Categories: cond-mat.stat-mech

\\

The mapping of the Nonlinear Schroedinger Equation with a random potential on

the Fokker-Planck equation is used to calculate the localization length of its

stationary states. The asymptotic growth rates of the moments of the wave

function and its derivative for the linear Schroedinger Equation in a random

potential are computed analytically and resummation is used to obtain the

corresponding growth rate for the nonlinear Schroedinger equation and the

localization length of the stationary states.

\\ ( http://arxiv.org/abs/0807.5005 , 14kb)

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arXiv:0807.5062

Date: Thu, 31 Jul 2008 13:46:29 GMT (51kb)

Title: Atom-atom correlations from condensate collisions

Authors: Magnus Ogren and K. V. Kheruntsyan

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

Comments: 4 pages, 1 figure

\\

We analyze atom-atom correlations in the s-wave scattering halo of two

colliding condensates. By developing a simple perturbative approach we obtain

explicit analytic results for the collinear (CL) and back-to-back (BB)

correlations corresponding to realistic density profiles of the colliding

condensates with interactions. The results in the short time limit are in

agreement with the first-principles simulations using the positive-P

representation and provide analytic insights to the experimental observations

of Perrin et al., Phys. Rev. Lett. 99, 150405 (2007). For long collision

durations, we predict that the BB correlation becomes broader than the CL

correlation.

\\ ( http://arxiv.org/abs/0807.5062 , 51kb)

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arXiv:0807.5110

Date: Thu, 31 Jul 2008 16:43:56 GMT (17kb)

Title: Thomas-Fermi versus one- and two-dimensional regimes of a trapped

dipolar Bose-Einstein condensate

Authors: N.G. Parker and D.H.J. O'Dell

Categories: cond-mat.other

Comments: 5 pages, 2 figures

\\

We derive the criteria for the Thomas-Fermi regime of a dipolar Bose-Einstein

condensate in cigar, pancake and spherical geometries. This also naturally

gives the criteria for the mean-field one- and two-dimensional regimes. Our

predictions, including the Thomas-Fermi density profiles, are shown to be in

excellent agreement with numerical solutions. Importantly, the anisotropy of

the interactions has a profound effect on the Thomas-Fermi/low-dimensional

criteria.

\\ ( http://arxiv.org/abs/0807.5110 , 17kb)

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arXiv:0807.5064

Date: Thu, 31 Jul 2008 13:47:29 GMT (280kb)

Title: A millisecond quantum memory for scalable quantum networks

Authors: Bo Zhao, Yu-Ao Chen, Xiao-Hui Bao, Thorsten Strassel, Chih-Sung Chuu,

Xian-Min Jin, J\"org Schmiedmayer, Zhen-Sheng Yuan, Shuai Chen, Jian-Wei Pan

Categories: quant-ph

Comments: 11pages, 4 figures, submitted for publication

\\

Scalable quantum information processing critically depends on the capability

of storage of a quantum state. In particular, a long-lived storable and

retrievable quantum memory for single excitations is of crucial importance to

the atomic-ensemble-based long-distance quantum communication. Although atomic

memories for classical lights and continuous variables have been demonstrated

with milliseconds storage time, there is no equal advance in the development of

quantum memory for single excitations, where only around 10 $\mu$s storage time

was achieved. Here we report our experimental investigations on extending the

storage time of quantum memory for single excitations. We isolate and identify

distinct mechanisms for the decoherence of spin wave (SW) in atomic ensemble

quantum memories. By exploiting the magnetic field insensitive state, ``clock

state", and generating a long-wavelength SW to suppress the dephasing, we

succeed in extending the storage time of the quantum memory to 1 ms. Our result

represents a substantial progress towards long-distance quantum communication

and enables a realistic avenue for large-scale quantum information processing.

\\ ( http://arxiv.org/abs/0807.5064 , 280kb)

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The replacements:

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arXiv:0804.4419

replaced with revised version Thu, 24 Jul 2008 22:34:25 GMT (1263kb)

Title: One-dimensional extended Hubbard model in the atomic limit

Authors: F. Mancini and F. P. Mancini

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

Comments: 28 pages;added references and corrected typos. This paper is an

extended version of Phys. Rev. E 77, 061120 (2008)

Journal-ref: Phys. Rev. E 77, 061120 (2008)

DOI: 10.1103/PhysRevE.77.061120

\\ ( http://arxiv.org/abs/0804.4419 , 1263kb)

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arXiv:0801.1103

replaced with revised version Mon, 28 Jul 2008 15:47:30 GMT (203kb)

Title: Berry Phase Effect on Exciton Transport and Bose Einstein Condensate

Authors: Wang Yao, Qian Niu

Categories: cond-mat.mes-hall

Comments: to appear in Phys. Rev. Lett

\\ ( http://arxiv.org/abs/0801.1103 , 203kb)

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arXiv:0803.1280 (*cross-listing*)

replaced with revised version Mon, 28 Jul 2008 17:37:50 GMT (726kb)

Title: The ground state energy at unitarity

Authors: Dean Lee (North Carolina State University)

Categories: nucl-th cond-mat.other hep-lat

Comments: 31 pages, 10 figures, version to appear in Phys. Rev. C

\\ ( http://arxiv.org/abs/0803.1280 , 726kb)

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arXiv:0807.0251

replaced with revised version Mon, 28 Jul 2008 20:42:06 GMT (1001kb,D)

Title: Symmetry-conserving vortex clusters in small rotating clouds of

ultracold bosons

Authors: Igor Romanovsky, Constantine Yannouleas, Uzi Landman

Categories: cond-mat.mes-hall cond-mat.other nucl-th physics.atm-clus

Comments: Revtex 4 with 4 color figures. Published version. Ref. [25]

(experimental) was added. For related papers, see

http://www.prism.gatech.edu/~ph274cy/

Journal-ref: Phys. Rev. A 78, 011606(R) (2008)

DOI: 10.1103/PhysRevA.78.011606

\\ ( http://arxiv.org/abs/0807.0251 , 1001kb)

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arXiv:0804.1429

replaced with revised version Wed, 30 Jul 2008 17:26:57 GMT (142kb)

Title: Temperature and final state effects in radio frequency spectroscopy

experiments on atomic Fermi gases

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

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

Comments: 4 pages, 4 figures

\\ ( http://arxiv.org/abs/0804.1429 , 142kb)

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arXiv:0711.0968

replaced with revised version Wed, 30 Jul 2008 20:38:59 GMT (73kb)

Title: Quantum Monte Carlo study of the visibility of one-dimensional

Bose-Fermi mixtures

Authors: C. N. Varney, V. G. Rousseau, R. T. Scalettar

Categories: cond-mat.other

Comments: 4 pages, 6 figures

Journal-ref: Phys. Rev. A 77, 041608(R) (2008)

DOI: 10.1103/PhysRevA.77.041608

\\ ( http://arxiv.org/abs/0711.0968 , 73kb)

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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 Tue Aug 26 2008 - 09:40:05 EST

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