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

Date: Mon, 16 Apr 2007 10:08:44 +1000 (EST)

Date: Mon, 16 Apr 2007 10:08:44 +1000 (EST)

Hi everyone,

This week is relatively quiet with 16 new abstracts and 9 replacements. The one

to catch my eye was on the critical behaviour of the Bose gas from the ETH

Zurich group - published a couple of weeks ago but only just on the arXiv.

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arXiv:0704.0842

Date: Fri, 6 Apr 2007 05:08:44 GMT (103kb)

Title: Oscillation bands of condensates on a ring: Beyond the mean field theory

Authors: Chengguang Bao

Categories: cond-mat.other

Comments: 7 pages, 8 figures

\\

The Hamiltonian of a N-boson system confined on a ring with zero spin and

repulsive interaction is diagonalized. The excitation of a pair of

p-wave-particles rotating reversely appears to be a basic mode. The fluctuation

of many of these excited pairs provides a mechanism of oscillation, the states

can be thereby classified into oscillation bands. The particle correlation is

studied intuitively via the two-body densities. Bose-clustering originating

from the symmetrization of wave functions is found, which leads to the

appearance of 1-, 2-, and 3-cluster structures. The motion is divided into

being collective and relative, this leads to the establishment of a relation

between the very high vortex states and the low-lying states.

\\ ( http://arxiv.org/abs/0704.0842 , 103kb)

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arXiv:0704.0925

Date: Fri, 6 Apr 2007 19:48:17 GMT (576kb)

Title: Spinor Dynamics in an Antiferromagnetic Spin-1 Condensate

Authors: A.T. Black, E. Gomez, L.D. Turner, S. Jung, P.D. Lett

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

Comments: 5 pages, 2 figures

\\

We observe coherent spin oscillations in an antiferromagnetic spin-1

Bose-Einstein condensate of sodium. The variation of the spin oscillations with

magnetic field shows a clear signature of nonlinearity, in agreement with

theory, which also predicts anharmonic oscillations near a critical magnetic

field. Measurements of the magnetic phase diagram agree with predictions made

in the approximation of a single spatial mode. The oscillation period yields

the best measurement to date of the sodium spin-dependent interaction

coefficient, determining that the difference between the sodium spin-dependent

s-wave scattering lengths $a_{f=2}-a_{f=0}$ is $2.47\pm0.27$ Bohr radii.

\\ ( http://arxiv.org/abs/0704.0925 , 576kb)

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arXiv:0704.0855

Date: Fri, 6 Apr 2007 08:06:59 GMT (314kb)

Title: Loading, cooling and trapping of Strontium using intercombinaison line

Authors: Thierry Chaneliere (LAC), Ling Xiang He, Robin Kaiser (INLN), David

Wilkowski (INLN)

Categories: physics.atom-ph

Comments: Submited to PRA (06/04/2007)

Proxy: ccsd hal-00140366

\\

The intercombinaison line of strontium at 689nm is successfully used in laser

cooling to reach the photon recoil limit with Doppler cooling in a

magneto-optical traps (MOT). In this paper we present a systematic study of the

loading efficiency of such a MOT. Comparing the experimental results to a

simple model allow us to discuss the actual limitation of our apparatus. We

also study in detail the final MOT regime emphasizing the role of the gravity

on the position, size and temperature along the vertical and horizontal

directions. At large laser detuning, one finds an unusual situation where

cooling and trapping occur in the presence of a high bias magnetic field.

\\ ( http://arxiv.org/abs/0704.0855 , 314kb)

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arXiv:0704.0912

Date: Fri, 6 Apr 2007 18:23:55 GMT (510kb)

Title: Nuclear Spin Effects in Optical Lattice Clocks

Authors: Martin M. Boyd, Tanya Zelevinsky, Andrew D. Ludlow, Sebastian Blatt,

Thomas Zanon-Willette, Seth M. Foreman, and Jun Ye

Categories: physics.atom-ph

Comments: 13 pages, 12 figures, submitted to PRA

\\

We present a detailed experimental and theoretical study of the effect of

nuclear spin on the performance of optical lattice clocks. With a state-mixing

theory including spin-orbit and hyperfine interactions, we describe the origin

of the $^1S_0$-$^3P_0$ clock transition and the differential $g$-factor between

the two clock states for alkaline-earth(-like) atoms, using $^{87}$Sr as an

example. Clock frequency shifts due to magnetic and optical fields are

discussed with an emphasis on those relating to nuclear structure. An

experimental determination of the differential $g$-factor in $^{87}$Sr is

performed and is in good agreement with theory. The magnitude of the tensor

light shift on the clock states is also explored experimentally. State specific

measurements with controlled nuclear spin polarization are discussed as a

method to reduce the nuclear spin-related systematic effects to below

10$^{-17}$ in lattice clocks.

\\ ( http://arxiv.org/abs/0704.0912 , 510kb)

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arXiv:0704.1089

Date: Mon, 9 Apr 2007 10:07:44 GMT (12kb)

Title: Representative Ensembles in Statistical Mechanics

Authors: V.I. Yukalov

Categories: cond-mat.stat-mech

Comments: Latex file, 18 pages

Journal-ref: Int. J. Mod. Phys. B 21 (2007) 69-86

\\

The notion of representative statistical ensembles, correctly representing

statistical systems, is strictly formulated. This notion allows for a proper

description of statistical systems, avoiding inconsistencies in theory. As an

illustration, a Bose-condensed system is considered. It is shown that a

self-consistent treatment of the latter, using a representative ensemble,

always yields a conserving and gapless theory.

\\ ( http://arxiv.org/abs/0704.1089 , 12kb)

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arXiv:0704.1096

Date: Mon, 9 Apr 2007 11:29:32 GMT (14kb)

Title: Horizon formation in isotropically expanding Bose-Einstein condensates

Authors: Yasunari Kurita, Takao Morinari

Categories: cond-mat.other

Comments: 4 pages, 2 figures

Report-no: YITP-07-16, OCU-PHYS-264, AP-GR-40

\\

We propose a simple experiment to create a sonic horizon in isotropically

trapped cold atoms within currently available experimental techniques.

Numerical simulation of the Gross-Pitaevskii equation shows that the sonic

horizon should appear by making the condensate expand. The expansion is

triggered by changing the interaction which can be controlled by the Feshbach

resonance in real experiments. The sonic horizon is shown to be quasi-static

for sufficiently strong interaction. The characteristic temperature that is

associated with particle emission from the horizon, which corresponds to the

Hawking temperature in an ideal situation, is estimated to be 2nK.

\\ ( http://arxiv.org/abs/0704.1096 , 14kb)

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arXiv:0704.1037

Date: Sun, 8 Apr 2007 17:37:34 GMT (591kb)

Title: Controlled collisions of a single atom and ion guided by movable

trapping potentials

Authors: Z. Idziaszek, T. Calarco, P. Zoller

Categories: quant-ph

Comments: 16 pages, 16 figures

\\

We consider a system composed of a trapped atom and a trapped ion. The ion

charge induces in the atom an electric dipole moment, which attracts it with an

r^{-4} dependence at large distances. In the regime considered here, the

characteristic range of the atom-ion interaction is comparable or larger than

the characteristic size of the trapping potential, which excludes the

application of the contact pseudopotential. The short-range part of the

interaction is described in the framework of quantum-defect theory, by

introducing some short-range parameters, which can be related to the s-wave

scattering length. When the separation between traps is changed we observe

trap-induced shape resonances between molecular bound states and vibrational

states of the external trapping potential. Our analysis is extended to

quasi-one-dimensional geometries, when the scattering exhibit

confinement-induced resonances, similar to the ones studied before for

short-range interactions. For quasi-one-dimensional systems we investigate the

effects of coupling between the center of mass and relative motion, which

occurs for different trapping frequencies of atom and ion traps. Finally, we

show how the two types of resonances can be employed for quantum state control

and spectroscopy of atom-ion molecules.

\\ ( http://arxiv.org/abs/0704.1037 , 591kb)

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arXiv:0704.1283

Date: Tue, 10 Apr 2007 18:07:48 GMT (693kb)

Title: Scanning tunnelling microscopy for ultracold atoms

Authors: Corinna Kollath, Michael K\"ohl, Thierry Giamarchi

Categories: cond-mat.str-el

\\

We propose a novel experimental probe for cold atomic gases analogous to the

scanning tunnelling microscope (STM) in condensed matter. This probe uses the

coherent coupling of a single particle to the system. Depending on the

measurement sequence, our probe allows to either obtain the \emph{local}

density, with a resolution on the nanometer scale, or the single particle

correlation function in real time. We discuss applications of this scheme to

the various possible phases for a two dimensional Hubbard system of fermions in

an optical lattice.

\\ ( http://arxiv.org/abs/0704.1283 , 693kb)

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arXiv:0704.1292

Date: Tue, 10 Apr 2007 19:06:32 GMT (444kb)

Title: Excitation of the dissipationless Higgs mode in a fermionic condensate

Authors: R. A. Barankov, L. S. Levitov

Categories: cond-mat.supr-con cond-mat.mes-hall

Comments: 4 pages, 4 figures

\\

The amplitude mode of a fermionic superfluid, analogous to the Higgs Boson,

becomes undamped in the strong coupling regime when its frequency is pushed

inside the BCS energy gap. We argue that this is the case in cold gases due to

the energy dispersion and nonlocality of the pairing interaction, and propose

to use the Feshbach resonance regime for parametric excitation of this mode.

The results presented for the BCS pairing dynamics indicate that even weak

dispersion suppresses dephasing and gives rise to persistent oscillations. The

frequency of oscillations extracted from our simulation of the BCS dynamics

agrees with the prediction of the many-body theory.

\\ ( http://arxiv.org/abs/0704.1292 , 444kb)

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arXiv:0704.1377

Date: Wed, 11 Apr 2007 09:05:29 GMT (723kb)

Title: Kibble-Zurek mechanism in a quenched ferromagnetic Bose-Einstein

condensate

Authors: Hiroki Saito, Yuki Kawaguchi, and Masahito Ueda

Categories: cond-mat.other

Comments: 11 pages, 7 figures

\\

The spin vortices are shown to be created through the Kibble-Zurek (KZ)

mechanism in a quantum phase transition of a spin-1 ferromagnetic Bose-Einstein

condensate, when the applied magnetic field is quenched below a critical value.

It is shown that the magnetic correlation functions have finite correlation

lengths, and magnetizations at widely separated positions grow in random

directions, resulting in spin vortices. We numerically confirm the scaling law

that the winding number of spin vortices is proportional to the square root of

the length of the closed path, and for slow quench, proportional to $\tau_{\rm

Q}^{-1/6}$ with $\tau_{\rm Q}$ being the quench time. The relation between the

spin conservation and the KZ mechanism is discussed.

\\ ( http://arxiv.org/abs/0704.1377 , 723kb)

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arXiv:0704.1389

Date: Wed, 11 Apr 2007 10:18:22 GMT (125kb)

Title: Gutzwiller description of non-magnetic Mott insulators: a dimer lattice

model

Authors: Michele Fabrizio (SISSA and ICTP, Trieste, Italy)

Categories: cond-mat.str-el

Comments: 15 pages, 9 figures

\\

We introduce a novel extension of the Gutzwiller variational wavefunction

able to deal with insulators that escape any mean-field like description, as

for instance non-magnetic insulators. As an application, we study the Mott

transition from a paramagnetic metal into a non-magnetic Peierls, or

valence-bond, Mott insulator. We analyze this model by means of our Gutzwiller

wavefunction analytically in the limit of large coordination lattices, where we

find that: (1) the Mott transition is first order; (2) the Peierls gap is large

in the Mott insulator, although it is mainly contributed by the electron

repulsion; (3) singlet-superconductivity arises around the transition.

\\ ( http://arxiv.org/abs/0704.1389 , 125kb)

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arXiv:0704.1413

Date: Wed, 11 Apr 2007 14:14:28 GMT (351kb)

Title: Preparation and detection of magnetic quantum phases in optical

superlattices

Authors: A. M. Rey, V. Gritsev, I. Bloch, E. Demler and M.D. Lukin

Categories: cond-mat.other

Comments: 10 pages, 2 Figures

\\

We describe a novel approach to prepare, detect and characterize magnetic

quantum phases in ultra-cold spinor atoms loaded in optical superlattices. Our

technique makes use of singlet-triplet spin manipulations in an array of

isolated double well potentials in analogy to recently demonstrated quantum

control in semiconductor quantum dots. We also discuss the many-body

singlet-triplet spin dynamics arising from coherent coupling between nearest

neighbor double wells and derive an effective description for such system. We

use it to study the generation of complex magnetic states by adiabatic and

non-equilibrium dynamics.

\\ ( http://arxiv.org/abs/0704.1413 , 351kb)

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arXiv:0704.1439

Date: Wed, 11 Apr 2007 15:45:24 GMT

Title: Critical Behavior of a Trapped Interacting Bose Gas

Authors: Tobias Donner, Stephan Ritter, Thomas Bourdel, Anton \"Ottl, Michael

K\"ohl, Tilman Esslinger

Categories: cond-mat.stat-mech

Comments: 4 pages, 3 figures, accepted version; published document available at

http://www.quantumoptics.ethz.ch/publications.html

Journal-ref: Science 315, 1556 (2007)

DOI: 10.1126/science.1138807

\\

The phase transition of Bose-Einstein condensation is studied in the critical

regime, when fluctuations extend far beyond the length scale of thermal de

Broglie waves. Using matter-wave interference we measure the correlation length

of these critical fluctuations as a function of temperature. The diverging

behavior of the correlation length above the critical temperature is observed,

from which we determine the critical exponent of the correlation length for a

trapped, weakly interacting Bose gas to be $\nu=0.67\pm 0.13$. This measurement

has direct implications for the understanding of second order phase

transitions.

\\ ( http://arxiv.org/abs/0704.1439 , )

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arXiv:0704.1539

Date: Thu, 12 Apr 2007 07:57:21 GMT (15kb)

Title: A New Monte Carlo Method and Its Implications for Generalized Cluster

Algorithms

Authors: C. H. Mak and Arun K. Sharma

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

Comments: 4 pages, 2 figures. Phys. Rev. Lett. (in press)

\\

We describe a novel switching algorithm based on a ``reverse'' Monte Carlo

method, in which the potential is stochastically modified before the system

configuration is moved. This new algorithm facilitates a generalized

formulation of cluster-type Monte Carlo methods, and the generalization makes

it possible to derive cluster algorithms for systems with both discrete and

continuous degrees of freedom. The roughening transition in the sine-Gordon

model has been studied with this method, and high-accuracy simulations for

system sizes up to $1024^2$ were carried out to examine the logarithmic

divergence of the surface roughness above the transition temperature, revealing

clear evidence for universal scaling of the Kosterlitz-Thouless type.

\\ ( http://arxiv.org/abs/0704.1539 , 15kb)

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arXiv:0704.1642

Date: Thu, 12 Apr 2007 18:49:58 GMT (51kb)

Title: Collective excitations of hard-core Bosons at half filling on square and

triangular lattices: Development of roton minima and collapse of roton gap

Authors: Tyler Bryant and Rajiv R. P. Singh

Categories: cond-mat.str-el

Comments: 10 pages, 7 figures

\\

We study ground state properties and excitation spectra for hard-core Bosons

on square and triangular lattices, at half filling, using series expansion

methods. Nearest-neighbor repulsion between the Bosons leads to the development

of short-range density order at the antiferromagnetic wavevector, and

simultaneously a roton minima in the density excitation spectra. On the

square-lattice, the model maps on to the well studied XXZ model, and the roton

gap collapses to zero precisely at the Heisenberg symmetry point, leading to

the well known spectra for the Heisenberg antiferromagnet. On the

triangular-lattice, the collapse of the roton gap signals the onset of the

supersolid phase. Our results suggest that the transition from the superfluid

to the supersolid phase maybe weakly first order. We also find several features

in the density of states, including two-peaks and a sharp discontinuity, which

maybe observable in experimental realization of such systems.

\\ ( http://arxiv.org/abs/0704.1642 , 51kb)

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arXiv:0704.1644

Date: Thu, 12 Apr 2007 18:55:27 GMT (164kb)

Title: Circulating Current States in Bilayer Fermionic and Bosonic Systems

Authors: Alexei Kolezhuk

Categories: cond-mat.other

Comments: 4 pages, 3 figures

\\

It is shown that fermionic polar molecules or atoms in a bilayer optical

lattice can undergo the transition to a state with circulating currents, which

spontaneously breaks the time reversal symmetry. Estimates of relevant

temperature scales are given and experimental signatures of the circulating

current phase are identified. Related phenomena in bosonic and spin systems

with ring exchange are discussed.

\\ ( http://arxiv.org/abs/0704.1644 , 164kb)

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arXiv:quant-ph/0609208

replaced with revised version Fri, 6 Apr 2007 08:44:12 GMT (222kb)

Title: Continuous transfer and laser guiding between two cold atom traps

Authors: Emiliya Dimova (LAC), Olivier Morizot (LPL), Guillaume Stern (LAC),

Carlos L. Garrido Alzar (LPL), Andrea Fioretti (LAC), Vincent Lorent (LPL),

Daniel Comparat (LAC), H{\'e}l{\`e}ne Perrin (LPL), Pierre Pillet (LAC)

Categories: quant-ph

Comments: 10 pages, 8 figures

Journal-ref: European physical Journal D 42 (2007) 299-308

DOI: 10.1140/epjd/e2007-00022-0

\\ ( http://arxiv.org/abs/quant-ph/0609208 , 222kb)

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arXiv:cond-mat/0608477

replaced with revised version Sat, 7 Apr 2007 20:24:23 GMT (48kb)

Title: Next-to-next-to-leading-order epsilon expansion for a Fermi gas at

infinite scattering length

Authors: Peter Arnold, Joaquin E. Drut, and Dam Thanh Son

Categories: cond-mat.other nucl-th

Comments: 28 pages, 14 figures

Report-no: INT PUB 06-12

Journal-ref: Phys.Rev. A75 (2007) 043605

DOI: 10.1103/PhysRevA.75.043605

\\ ( http://arxiv.org/abs/cond-mat/0608477 , 48kb)

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arXiv:cond-mat/0610079

replaced with revised version Mon, 9 Apr 2007 13:11:09 GMT (319kb)

Title: Adiabatic Phase Diagram of an Ultracold Atomic Fermi Gas with a Feshbach

Resonance

Authors: S. Watabe, T. Nikuni, N. Nygaard, J. E. Williams, and C. W. Clark

Categories: cond-mat.other

Comments: 13 pages, 8 figures. In press, "Journal of the Physical Society of

Japan", Vol.76, No.6

\\ ( http://arxiv.org/abs/cond-mat/0610079 , 319kb)

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arXiv:cond-mat/0610610

replaced with revised version Sun, 8 Apr 2007 13:57:38 GMT (304kb)

Title: Asymmetric Fermion Superfluid with Inter- and Intra-Species Pairings

Authors: Xuguang Huang, Xuewen Hao and Pengfei Zhuang

Categories: cond-mat.supr-con hep-ph

Comments: 4 pages, 4 figures

\\ ( http://arxiv.org/abs/cond-mat/0610610 , 304kb)

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arXiv:cond-mat/0701321

replaced with revised version Fri, 6 Apr 2007 21:38:18 GMT (14kb)

Title: Ultraslow optical waveguiding in an atomic Bose-Einstein condensate

Authors: Devrim Tarhan, Nazmi Postacioglu, Ozgur E. Mustecaplioglu

Categories: cond-mat.other quant-ph

Comments: 9 pages, 3 figures

Journal-ref: Opt. Lett. 32(9), 1038-1040 (2007)

\\ ( http://arxiv.org/abs/cond-mat/0701321 , 14kb)

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arXiv:0704.0289

replaced with revised version Tue, 10 Apr 2007 17:25:34 GMT (292kb)

Title: Kosterlitz-Thouless Crossover on a Two-Dimensional Lattice of

Josephson-Coupled Bose-Einstein Condensates

Authors: V. Schweikhard, S. Tung, and E. A. Cornell

Categories: cond-mat.mes-hall

Comments: corrected wording errors in introduction paragraph

\\ ( http://arxiv.org/abs/0704.0289 , 292kb)

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arXiv:cond-mat/0701751

replaced with revised version Tue, 10 Apr 2007 09:11:10 GMT (571kb)

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

\\ ( http://arxiv.org/abs/cond-mat/0701751 , 571kb)

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arXiv:quant-ph/0612214

replaced with revised version Wed, 11 Apr 2007 01:54:11 GMT (500kb)

Title: Manipulation of the quantum state by Majorana transition in spinor

Bose-Einstein condensates

Authors: Lin Xia, Xu Xu, Fan Yang, Wei Xiong, Juntao Li, Qianli Ma, Xiaoji

Zhou, Hong Guo and Xuzong Chen

Categories: quant-ph cond-mat.other

Comments: 5 pages, 5 figures

\\ ( http://arxiv.org/abs/quant-ph/0612214 , 500kb)

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arXiv:0704.1413

replaced with revised version Thu, 12 Apr 2007 18:10:12 GMT (351kb)

Title: Preparation and detection of magnetic quantum phases in optical

superlattices

Authors: A. M. Rey, V. Gritsev, I. Bloch, E. Demler and M.D. Lukin

Categories: cond-mat.other

Comments: 5 pages, 2 Figures, reference added

\\ ( http://arxiv.org/abs/0704.1413 , 351kb)

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Till next week,

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 Apr 16 2007 - 10:08:44 EST

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