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

Date: Wed, 21 Oct 2009 19:22:27 +1000

Date: Wed, 21 Oct 2009 19:22:27 +1000

Dear subscribers,

This week was compiled by Simon Haine, and contains 30 new abstracts and 12

replacements.

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arXiv:0908.4200

Date: Fri, 28 Aug 2009 12:59:11 GMT (670kb)

Title: Adiabatic transport of Bose-Einstein condensate in double-well trap

Authors: V.O. Nesterenko, A.N. Novikov, A.Yu. Cherny, F.F. de Souza Cruz, and

E. Suraud

Categories: cond-mat.quant-gas cond-mat.other

Comments: 8 pages, 8 figures, submitted to J.Phys.B

\\

A complete irreversible adiabatic transport of Bose-Einstein condensate (BEC)

in a double-well trap is investigated within the mean field approximation. The

transfer is driven by time-dependent (Gaussian) coupling between the wells and

their relative detuning. The protocol successfully works in a wide range of

both repulsive and attractive BEC interaction. The nonlinear effects caused by

the interaction can be turned from detrimental into favorable for the

transport. The results are compared with familiar Landau-Zener scenarios using

the constant coupling. It is shown that the pulsed Gaussian coupling provides a

new transport regime where coupling edges are decisive and convenient switch of

the transport is possible.

\\ ( http://arxiv.org/abs/0908.4200 , 670kb)

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arXiv:0908.4147

Date: Fri, 28 Aug 2009 07:40:10 GMT (163kb)

Title: Experimental comparison of Raman and RF outcouplers for high flux atom

lasers

Authors: J. E. Debs, D. D\"oring, P. A. Altin, C. Figl, J. Dugu\'e, M.

Jeppesen, J. T. Schultz, N. P. Robins, J. D. Close

Categories: quant-ph physics.atom-ph

Comments: 8 Pages, 5 Figures, Submitted to PRA

\\

We study the properties of an atom laser beam derived from a Bose-Einstein

condensate using three different outcouplers, one based on multi-state radio

frequency transitions and two others based on Raman transitions capable of

imparting momentum to the beam. We first summarize the differences that arise

in such systems, and how they may impact on the use of an atom laser in

interferometry. Experimentally, we examine the formation of a bound state in

all three outcouplers, a phenomenon which limits the atom laser flux, and find

that a two-state Raman outcoupler is the preferred option for high flux, low

divergence atom laser beams.

\\ ( http://arxiv.org/abs/0908.4147 , 163kb)

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arXiv:0908.4313

Date: Sat, 29 Aug 2009 02:39:35 GMT (104kb)

Title: Aligned dipolar Bose-Einstein condensate in a double-well potential:

From cigar-shaped to pancake-shaped

Authors: M. Asad-uz-Zaman and D. Blume

Categories: cond-mat.quant-gas

Comments: 21 pages, 16 figures

\\

We consider a Bose-Einstein condensate (BEC), which is characterized by

long-range and anisotropic dipole-dipole interactions and vanishing s-wave

scattering length, in a double-well potential. The properties of this system

are investigated as functions of the height of the barrier that splits the

harmonic trap into two halves, the number of particles (or dipole-dipole

strength) and the aspect ratio $\lambda$, which is defined as the ratio between

the axial and longitudinal trapping frequencies $\omega_z$ and $\omega_{\rho}$.

The phase diagram is determined by analyzing the stationary mean-field

solutions. Three distinct regions are found: a region where the energetically

lowest lying stationary solution is symmetric, a region where the energetically

lowest lying stationary solution is located asymmetrically in one of the wells,

and a region where the system is mechanically unstable. For sufficiently large

aspect ratio $\lambda$ and sufficiently high barrier height, the system

consists of two connected quasi-two-dimensional sheets with density profiles

whose maxima are located either at $\rho=0$ or away from $\rho=0$. The

stability of the stationary solutions is investigated by analyzing the

Bogoliubov de Gennes excitation spectrum and the dynamical response to small

perturbations. These studies reveal unique oscillation frequencies and distinct

collapse mechanisms. The results derived within the mean-field framework are

complemented by an analysis based on a two-mode model.

\\ ( http://arxiv.org/abs/0908.4313 , 104kb)

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arXiv:0908.4513

Date: Mon, 31 Aug 2009 12:12:57 GMT (14kb)

Title: Quantum decay of dark solitons in one dimensional Bose systems

Authors: D.M. Gangardt, A. Kamenev

Categories: cond-mat.quant-gas cond-mat.stat-mech

Comments: 4 pages, 1 figure

\\

We study dissipative dynamics of a dark soliton at temperatures $T$ lower

than the chemical potential $\mu$ of the background Bose liquid. We show that,

unless the system is integrable, the Raman scattering of phonons leads to a

finite lifetime $\tau\sim (T/\mu)^{-4} $ of the dark soliton. This behavior is

qualitatively different from $\tau\sim (T/\mu)^{-1}$, obtained earlier in the

high temperature regime, and reflects regime of ``cold'' quantum phonons.

Coherence of such phonons manifests itself in long-range soliton-soliton

interactions mediated by the superradiation.

\\ ( http://arxiv.org/abs/0908.4513 , 14kb)

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arXiv:0908.4568

Date: Mon, 31 Aug 2009 16:13:17 GMT (321kb)

Title: Creating p-wave superfluids and topological excitations in optical

lattices

Authors: P. Massignan, A. Sanpera, M. Lewenstein

Categories: cond-mat.quant-gas

Comments: 4 pages, 4 figures

\\

We propose various optical lattice setups as viable routes towards the

realization of a stable p-wave superfluid. We analyze the vortex excitations on

the lattice with a self-consistent Bogolubov-de Gennes calculation, showing

that the topological zero-energy Majorana mode known to exist in the continuum

survives in the experimentally relevant conditions of finite lattices and

external trapping. Lattice effects are strongest at half-filling: here the

linearity of the low-lying spectrum is lost, and the Majorana mode acquires a

d-wave symmetry, becoming supersolid. When the vortex rotates in the same

direction as the chirality, supersolidity is attained through a quantum phase

transition, over which the Majorana mode changes parity and spreads over the

whole lattice.

\\ ( http://arxiv.org/abs/0908.4568 , 321kb)

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arXiv:0908.4458

Date: Mon, 31 Aug 2009 05:23:02 GMT (256kb)

Title: An exactly solvable phase transition model: generalized statistics and

generalized Bose-Einstein condensation

Authors: Wu-Sheng Dai and Mi Xie

Categories: cond-mat.stat-mech cond-mat.quant-gas

Comments: 17 pages, 2 figures

Journal-ref: J. Stat. Mech. (2009) P07034

\\

In this paper, we present an exactly solvable phase transition model in which

the phase transition is purely statistically derived. The phase transition in

this model is a generalized Bose-Einstein condensation. The exact expression of

the thermodynamic quantity which can simultaneously describe both gas phase and

condensed phase is solved with the help of the homogeneous Riemann-Hilbert

problem, so one can judge whether there exists a phase transition and determine

the phase transition point mathematically rigorously. A generalized statistics

in which the maximum occupation numbers of different quantum states can take on

different values is introduced, as a generalization of Bose-Einstein and

Fermi-Dirac statistics.

\\ ( http://arxiv.org/abs/0908.4458 , 256kb)

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arXiv:0908.4583

Date: Mon, 31 Aug 2009 17:11:36 GMT (286kb)

Title: Collective Motion of Polarized Dipolar Fermi Gases in the Hydrodynamic

Regime

Authors: Aristeu R. P. Lima, Axel Pelster

Categories: cond-mat.quant-gas

\\

Recently, a seminal STIRAP experiment allowed the creation of 40K87Rb

molecules in the rovibrational ground state [K.-K. Ni et al., Science 322, 231

(2008)]. In order to describe such a polarized dipolar Fermi gas in the

hydrodynamic regime, we work out a variational time-dependent Hartree-Fock

approach. With this we calculate dynamical properties of such a system as, for

instance, the frequencies of the low-lying excitations and the time-of-flight

expansion. We find remarkable effects of a strong dipole-dipole interaction

such as anisotropic breathing oscillations in momentum space and a suppression

of the aspect-ratio inversion after release of the harmonic trap.

\\ ( http://arxiv.org/abs/0908.4583 , 286kb)

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arXiv:0908.4589

Date: Mon, 31 Aug 2009 18:00:26 GMT (65kb)

Title: Dynamical mean-field theory for light fermion--heavy boson mixtures on

optical lattices

Authors: M. Iskin and J. K. Freericks

Categories: cond-mat.quant-gas cond-mat.str-el

Comments: 10 pages with 4 figures

\\

We theoretically analyze Fermi-Bose mixtures consisting of light fermions and

heavy bosons that are loaded into optical lattices (ignoring the trapping

potential). To describe such mixtures, we consider the Fermi-Bose version of

the Falicov-Kimball model on a periodic lattice. This model can be exactly

mapped onto the spinless Fermi-Fermi Falicov-Kimball model at zero temperature

for all parameter space as long as the mixture is thermodynamically stable. We

employ dynamical mean-field theory to investigate the evolution of the

Fermi-Bose Falicov-Kimball model at higher temperatures. We calculate spectral

moment sum rules for the retarded Green's function and self-energy, and use

them to benchmark the accuracy of our numerical calculations, as well as to

reduce the computational cost by exactly including the tails of infinite

summations or products. We show how the occupancy of the bosons,

single-particle many-body density of states for the fermions, momentum

distribution, and the average kinetic energy evolve with temperature. We end by

briefly discussing how to experimentally realize the Fermi-Bose Falicov-Kimball

model in ultracold atomic systems.

\\ ( http://arxiv.org/abs/0908.4589 , 65kb)

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arXiv:0908.4337

Date: Sat, 29 Aug 2009 17:07:26 GMT (535kb)

Title: Deterministic generation of non-classical states of light using photon

blockade

Authors: Andrei Faraon, Arka Majumdar and Jelena Vuckovic

Categories: quant-ph

\\

The generation of non-classical states of light via photon blockade with

time-modulated input is analyzed. We show that improved single photon

statistics can be obtained by adequately choosing the parameters of the driving

laser pulses. An alternative method, where the system is driven via a

continuous wave laser and the frequency of the dipole is controlled (e.g.

electrically) at very fast timescales is presented.

\\ ( http://arxiv.org/abs/0908.4303 , 535kb)

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arXiv:0908.4337

Date: Sat, 29 Aug 2009 17:07:26 GMT (1494kb)

Title: Some entanglement features of three-atoms Tavis-Cummings model:

Cooperative case

Authors: M. Youssef, A.-S. F. Obada and N. Metwally

Categories: quant-ph

Comments: 14 pages, 7 figures

\\

In this paper we consider a system of identical three two-level atoms

interacting at resonance with a single-mode of the quantized field in a

lossless cavity. The initial cavity field is prepared in the coherent state

while the atoms are taken initially to be either in the uppermost excited state

"$|eee>$" or The $\textmd{GHZ}$-state or the $\textmd{W}$-state. For this

system we investigate different kinds of atomic inversion and entanglement,

which arise between the different parts of the system due to the interaction.

Also the relationship, between entanglement and some other nonclassical effects

in the statistical properties, such as collapses and revivals in the atomic

inversion where superharmonic effects appear, is discussed. The $Q$-functions

for different cases are discussed. Most remarkably it is found that the

$\textmd{GHZ}$-state is more robust against energy losses, showing almost

coherent trapping and Schr\"odinger-cat states can not be produced from such

state. Also the entanglement of $\textmd{GHZ}$-state is more robust than the

$\textmd{W}$-state. Another interesting feature found is that the state which

has no pairwise entanglement initially will have a much improvement of such

pairwise entanglement through the evolution. Sudden death and sudden revival of

atoms-pairwise entanglement are produced with the $\textmd{W}$-state.

\\ ( http://arxiv.org/abs/0908.4337 , 1494kb)

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arXiv:0908.4348

Date: Sat, 29 Aug 2009 17:07:26 GMT (314kb)

Title: Relational Blockworld Interpretation of Quantum Field Theory

Authors: W.M. Stuckey, Timothy McDevitt and Michael Silberstein

Categories: quant-ph

Comments: 38 pages text, 8 figures

\\

We propose a new interpretation of quantum field theory (QFT) based on our

interpretation of non-relativistic quantum mechanics called Relational

Blockworld. In our interpretation, QFT is the continuous approximation of a

more fundamental, discrete theory whereby the transition amplitude Z is not

viewed as a sum over all paths in configuration space, but is a mathematical

machine for measuring the symmetry of the differential operator and source

vector of the discrete action in determining the relative locations of

individual detector clicks. We propose that the differential operator and

source vector of the underlying discrete theory are related via a

self-consistency criterion (SCC) based on a discrete counterpart to the

identity that underwrites divergence-free sources in classical field theory,

i.e., the boundary of a boundary is zero. Thereby Z is constructed from the

SCC, rather than classical field theory, and QFT is the continuous

approximation using trajectories, rather than individual detector clicks, as

the fundamental entities. In order to illustrate this interpretation, we

construct a candidate for the SCC using a discrete path integral formalism over

graphs. In this specific approach, the SCC is a tautology, based on the

boundary of a boundary is zero, that ensures the source vector is

divergence-free and resides in the row space of the differential operator.

Accordingly, the differential operator will necessarily have an eigenvector

with eigenvalue zero, so the SCC is the origin of gauge invariance. Using this

formalism, we obtain the two-source transition amplitude over a

(1+1)-dimensional graph with N vertices fundamental to the scalar Gaussian

theory.

\\ ( http://arxiv.org/abs/0908.4348 , 314kb)

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arXiv:0908.4473

Date: Mon, 31 Aug 2009 08:21:21 GMT (169kb)

Title: Unequal intensity splitting can reduce back action in interferometers

Authors: Ole Steuernagel

Categories: quant-ph

Comments: 3 pages, 2 figures

\\

Typical two-path interferometers are intensity-balanced because this

maximizes the visibility of their interference patterns. Unbalancing the

interferometer can be advised when back action on the object whose position is

monitored is to be reduced. Variations of the intensity splitting ratios in

two-path interferometers are analyzed in order to determine optimal

interferometric performance while minimizing back action: it turns out that

homodyning-like schemes perform best.

\\ ( http://arxiv.org/abs/0908.4473 , 169kb)

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arXiv:0908.4475

Date: Mon, 31 Aug 2009 08:26:26 GMT (773kb)

Title: Multi-barrier resonant tunneling for the one-dimensional nonlinear

Schr\"odinger Equation

Authors: K Rapedius and H J Korsch

Categories: quant-ph

Comments: 22 pages, 11 figures

\\

For the stationary one-dimensional nonlinear Schr\"odinger equation (or

Gross-Pitaevskii equation) nonlinear resonant transmission through a finite

number of equidistant identical barriers is studied using a (semi-) analytical

approach. In addition to the occurrence of bistable transmission peaks known

from nonlinear resonant transmission through a single quantum well

(respectively a double barrier) complicated (looped) structures are observed in

the transmission coefficient which can be identified as the result of symmetry

breaking similar to the emergence of self-trapping states in double well

potentials. Furthermore it is shown that these results are well reproduced by a

nonlinear oscillator model based on a small number of resonance eigenfunctions

of the corresponding linear system.

\\ ( http://arxiv.org/abs/0908.4475 , 773kb)

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arXiv:0908.4444

Date: Tue, 1 Sep 2009 14:40:27 GMT (348kb)

Title: Upper Limit on the Magnetic Dipole Contribution to the 5p-8p Transition

in Rb by Use of Ultracold Atom Spectroscopy

Authors: R. Pires, M. Ascoli, E. E. Eyler, P. L. Gould, and A. Derevianko

Categories: physics.atom-ph

Comments: 7 pages, 4 figures, 3 tables

\\

We report on hyperfine-resolved spectroscopic measurements of the

electric-dipole forbidden 5$p_{3/2} \to 8p_{1/2}$ transition in a sample of

ultracold $^{87}$Rb atoms. The hyperfine selection rules enable the weak

magnetic-dipole (M1) contribution to the transition strength to be

distinguished from the much stronger electric-quadrupole (E2) contribution. An

upper limit on the M1 transition strength is determined that is about 50 times

smaller than an earlier experimental determination. We also calculate the

expected value of the M1 matrix element and find that it is less than the upper

limit extracted from the experiment.

\\ ( http://arxiv.org/abs/0908.4444 , 348kb)

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arXiv:0909.0195

Date: Tue, 1 Sep 2009 14:40:27 GMT (696kb)

Title: Interaction-induced dynamical phase locking of Bose-Einstein condensates

Authors: Erez Boukobza, Doron Cohen, and Amichay Vardi

Categories: cond-mat.quant-gas

Comments: 4 pages, 5 figures

\\

We show that interactions result in the emergence of a {\it definite}

relative-phase between two initially incoherent Bose-Einstein condensates. The

many-realization interference fringe visibility is universal at

$g_{12}^{(1)}\sim1/3$ throughout the Josephson interaction regime, as evident

from a semiclassical picture. Other types of incoherent preparation yield

qualitatively different coherence dynamics.

\\ ( http://arxiv.org/abs/0909.0195 , 696kb)

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arXiv:0909.0102

Date: Tue, 1 Sep 2009 19:55:51 GMT (117kb)

Title: Double diffraction in an atomic gravimeter

Authors: Nicola Malossi (SYRTE), Quentin Bodart (SYRTE), S\'ebastien Merlet

(SYRTE), Arnaud Landragin (SYRTE), Franck Pereira Dos Santos (SYRTE)

Categories: physics.atom-ph

\\

We demonstrate the realization of a new scheme for cold atom gravimetry based

on the use of double diffraction beamsplitters recently demonstrated in

\cite{Leveque}, where the use of two retro-reflected Raman beams allows

symmetric diffraction in $\pm \hbar k_{eff}$ momenta. Though in principle

restricted to the case of zero Doppler shift, for which the two pairs of Raman

beams are simultaneously resonant, we demonstrate that such diffraction pulses

can remain efficient on atoms with non zero velocity, such as in a gravimeter,

when modulating the frequency of one of the two Raman laser sources. We use

such pulses to realize an interferometer insensitive to laser phase noise and

some of the dominant systematics. This reduces the technical requirements and

would allow the realization of a simple atomic gravimeter. We demonstrate a

sensitivity of $1.2\times10^{-7}g$ per shot.

\\ ( http://arxiv.org/abs/0909.0102 , 117kb)

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arXiv:0909.0249

Date: Tue, 1 Sep 2009 19:55:51 GMT (1051kb)

Title: Large spin relaxation rates in trapped submerged-shell atoms

Authors: Colin B. Connolly, Yat Shan Au, S. Charles Doret, Wolfgang Ketterle,

John M. Doyle

Categories: physics.atom-ph

Comments: 10 pages, 3 figures

\\

Spin relaxation due to atom-atom collisions is measured for magnetically

trapped erbium and thulium atoms at a temperature near 500 mK. The rate

constants for Er-Er and Tm-Tm collisions are 3.0 times 10^-10 cm^3 s^-1 and 1.1

times 10^-10 cm^3 s^-1, respectively, 2-3 orders of magnitude larger than those

observed for highly magnetic S-state atoms. This is strong evidence for an

additional, dominant, spin relaxation mechanism, electrostatic anisotropy, in

collisions between these "submerged-shell" L > 0 atoms. These large spin

relaxation rates imply that evaporative cooling of these atoms in a magnetic

trap will be highly inefficient.

\\ ( http://arxiv.org/abs/0909.0249 , 1051kb)

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arXiv:0909.0416

Date: Wed, 2 Sep 2009 15:31:28 GMT (3637kb)

Title: Functional renormalization and ultracold quantum gases

Authors: S. Floerchinger

Categories: cond-mat.quant-gas

Comments: doctoral thesis, 187 pages, 60 figures

\\

The method of functional renormalization is applied to the theoretical

investigation of ultracold quantum gases. Flow equations are derived for a Bose

gas with approximately pointlike interaction, for a Fermi gas with two

(hyperfine) spin components in the Bardeen-Cooper-Schrieffer (BCS) to

Bose-Einstein condensation (BEC) crossover and for a Fermi gas with three

components. The solution of the flow equations determine the properties of

these systems both in the few-body regime and in thermal equilibrium.

For the Bose gas this covers the quantum phase diagram, the condensate and

superfluid fraction, the critical temperature, the correlation length, the

specific heat or sound propagation. The properties are discussed both for three

and two spatial dimensions. The discussion of the Fermi gas in the BCS-BEC

crossover concentrates on the effect of particle-hole fluctuations but

addresses the complete phase diagram. For the three component fermions, the

flow equations in the few-body regime show a limit-cycle scaling and the Efimov

tower of three-body bound states. Applied to the case of Lithium they explain

recently observed three-body loss features. Extending the calculations by

continuity to nonzero density, it is found that a new trion phase separates a

BCS and a BEC phase for three component fermions close to a common resonance.

More formal is the derivation of a new exact flow equation for scale

dependent composite operators. This equation allows for example a better

treatment of bound states.

\\ ( http://arxiv.org/abs/0909.0416 , 3637kb)

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arXiv:0909.0489

Date: Wed, 2 Sep 2009 18:24:16 GMT (1515kb)

Title: Spin-dependent inelastic collisions in spin-2 Bose-Einstein condensates

Authors: Satoshi Tojo, Taro Hayashi, Tatsuyoshi Tanabe, Takuya Hirano, Yuki

Kawaguchi, Hiroki Saito, and Masahito Ueda

Categories: cond-mat.quant-gas

Comments: 7 pages, 5 figures

\\

We studied spin-dependent two-body inelastic collisions in F=2 87Rb

Bose-Einstein condensates both experimentally and theoretically. The 87Rb

condensates were confined in an optical trap and selectively prepared in

various spin states in the F=2 manifold at a magnetic field of 3.0 G. Measured

atom loss rates are found to depend on spin states of colliding atoms. We

measured two fundamental loss coefficients for two-body inelastic collisions

with the total spin of 0 and 2; the coefficients determine loss rates for all

the spin pairs. The experimental results for mixtures of all the spin

combinations are in good agreement with numerical solutions of the

Gross-Pitaevskii equations that include the effect of a magnetic field

gradient.

\\ ( http://arxiv.org/abs/0909.0489 , 1515kb)

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arXiv:0909.0491

Date: Wed, 2 Sep 2009 19:18:46 GMT (2783kb)

Title: Light scattering for thermometry of fermionic atoms in an optical

lattice

Authors: J. Ruostekoski, C. J. Foot, and A. B. Deb

Categories: cond-mat.quant-gas

Comments: submitted to PRL in January 2009

\\

We propose a method for measuring the temperature of fermionic atoms in an

optical lattice potential from the intensity of the scattered light in the

far-field diffraction pattern. We consider a single-component gas in a

tightly-confined two-dimensional lattice, illuminated by far off-resonant light

driving a cycling transition. Our calculations show that thermal correlations

of the fermionic atoms generate fluctuations in the intensity of the

diffraction pattern of light scattered from the atomic lattice array and that

this signal can be accurately detected above the shot noise using a lens to

collect photons scattered in a forward direction (with the diffraction maxima

blocked). The sensitivity of the thermometer is enhanced by an additional

harmonic trapping potential.

\\ ( http://arxiv.org/abs/0909.0491 , 2783kb)

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arXiv:0909.0311

Date: Wed, 2 Sep 2009 03:42:46 GMT (150kb)

Title: Revival-collapse phenomenon in the quadrature squeezing of the

multiphoton intensity-dependent Jaynes-Cummings model

Authors: Faisal A A El-Orany

Categories: quant-ph

Comments: 14 pages, 6 figures

Journal-ref: J. Mod. Opt. 53 (2006) 1699-1714

\\

For multiphoton intensity-dependent Jaynes-Cummings model (JCM), which is

described by two-level atom interacting with a radiation field, we prove that

there is a relationship between the atomic inversion and the quadrature

squeezing. We give the required condition to obtain best information from this

relation. Also we show that this relation is only sensitive to large values of

the detuning parameter. Furthermore, we discuss briefly such relation for the

off-resonance standard JCM.

\\ ( http://arxiv.org/abs/0909.0311 , 150kb)

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arXiv:0909.0728

Date: Thu, 3 Sep 2009 19:56:49 GMT (213kb,D)

Title: Simulating and detecting artificial magnetic fields in trapped atoms

Authors: Matthias Rosenkranz, Alexander Klein, Dieter Jaksch

Categories: cond-mat.quant-gas cond-mat.other

Comments: 14 pages, 9 figures

\\

A Bose-Einstein condensate exhibiting a nontrivial phase induces an

artificial magnetic field in immersed impurity atoms trapped in a stationary,

ring-shaped optical lattice. We present an effective Hamiltonian for the

impurities for two condensate setups: the condensate in a rotating ring and in

an excited rotational state in a stationary ring. We use Bogoliubov theory to

derive analytical formulas for the induced artificial magnetic field and the

hopping amplitude in the limit of low condensate temperature where the impurity

dynamics is coherent. As methods for observing the artificial magnetic field we

discuss time of flight imaging and mass current measurements. Moreover, we

compare the analytical results of the effective model to numerical results of a

corresponding two-species Bose-Hubbard model. We also study numerically the

clustering properties of the impurities and the quantum chaotic behavior of the

two-species Bose-Hubbard model.

\\ ( http://arxiv.org/abs/0909.0728 , 213kb)

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arXiv:0909.0536

Date: Wed, 2 Sep 2009 22:00:08 GMT (149kb)

Title: Variational ansatz for the nonlinear Landau-Zener problem for cold atom

association

Authors: A. Ishkhanyan, B. Joulakian, and K.-A. Suominen

Categories: cond-mat.quant-gas

\\

We present a rigorous analysis of the Landau-Zener linear-in-time term

crossing problem for quadratic-nonlinear systems relevant to the coherent

association of ultracold atoms in degenerate quantum gases. Our treatment is

based on an exact third-order nonlinear differential equation for the molecular

state probability. Applying a variational two-term ansatz we construct a simple

approximation that accurately describes the whole time dynamics of coupled

atom-molecular system for any set of involved parameters. Assuring an absolute

error less than for the final transition probability, the resultant solution

improves, by several orders of magnitude, the accuracy of the previous

approximations by A. Ishkhanyan et al. developed separately for the weak

coupling [J. Phys. A 38, 3505 (2005)] and strong interaction [J. Phys. A 39,

14887 (2006)] limits. In addition, the constructed approximation covers the

whole moderate coupling regime providing for this intermediate regime the same

accuracy as for the two mentioned limits. The obtained results reveal a

remarkable observation that for the strong coupling limit the resonance

crossing is mostly governed by the nonlinearity while the coherent

atom-molecular oscillations coming up soon after the resonance has been crossed

are basically of linear nature. This observation is supposed to be of general

character due to the basic attributes of the resonance crossing processes in

the nonlinear quantum systems of the discussed type of involved quadratic

nonlinearity.

\\ ( http://arxiv.org/abs/0909.0536 , 149kb)

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arXiv:0909.0565

Date: Thu, 3 Sep 2009 03:37:26 GMT (693kb)

Title: Magnetic Crystallization of a Ferromagnetic Bose-Einstein Condensate

Authors: Yuki Kawaguchi, Hiroki Saito, Kazue Kudo, and Masahito Ueda

Categories: cond-mat.quant-gas

Comments: 4pages, 4 figures

\\

We use mean-field theory to show that magnetic crystallization emerges in a

spin-1 ferromagnetic Bose-Einstein condensate with magnetic dipole-dipole

interaction. The periodicity of the checkerboard pattern is about three times

as large as that observed by the Berkeley group [Phys. Rev. Lett. {\bf 100},

170403 (2008)], and the pattern eventually dissolves. The stationary spin

configuration of the system is determined by the interplay between the dipole

interaction and the quadratic Zeeman effect.

\\ ( http://arxiv.org/abs/0909.0565 , 693kb)

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arXiv:0909.0652

Date: Thu, 3 Sep 2009 13:47:04 GMT (229kb)

Title: Spinor BECs in a double-well: population transfer and Josephson

oscillations

Authors: B. Julia-Diaz, M. Mele-Messeguer, M. Guilleumas, A. Polls

Categories: cond-mat.other cond-mat.quant-gas

\\

The dynamics of an F=1 spinor condensate in a two-well potential is studied

within the framework of the Gross-Pitaevskii equation. We derive two-mode

equations relating the population imbalances, the phase differences among the

condensates at each side of the barrier and the time evolution of the different

Zeeman populations for the case of small population imbalances. The case of

zero total magnetization is scrutinized in this limit demonstrating the ability

of a two mode analysis to describe to a large extent the dynamics observed in

the Gross-Pitaevskii equations. It is also demonstrated that the time evolution

of the different total populations fully decouples from the Josephson tunneling

phenomena. All the relevant time scales are clearly identified with microscopic

properties of the atom-atom interactions.

\\ ( http://arxiv.org/abs/0909.0652 , 229kb)

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arXiv:0909.0678

Date: Thu, 3 Sep 2009 15:05:19 GMT (1436kb,D)

Title: Microwave Control of Atomic Motion in Optical Lattices

Authors: Leonid F\"orster, Micha{\l} Karski, Jai-Min Choi, Andreas Steffen,

Wolfgang Alt, Dieter Meschede, Artur Widera, Enrique Montano, Jae Hoon Lee,

Worawarong Rakreungdet and Poul S. Jessen

Categories: quant-ph physics.atom-ph

Comments: 4 pages, 5 figures

\\

We control the quantum mechanical motion of neutral atoms in an optical

lattice by driving microwave transitions between spin states whose trapping

potentials are spatially offset. Control of this offset with nanometer

precision allows for adjustment of the coupling strength between different

motional states, analogous to an adjustable effective Lamb-Dicke factor. This

is used both for efficient one-dimensional sideband cooling of individual atoms

to a vibrational ground state population of 97%, and to drive coherent Rabi

oscillation between arbitrary pairs of vibrational states. We further show that

microwaves can drive well resolved transitions between motional states in

maximally offset, shallow lattices, and thus in principle allow for coherent

control of long range quantum transport.

\\ ( http://arxiv.org/abs/0909.0678 , 1436kb)

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\\

arXiv:0909.0705

Date: Thu, 3 Sep 2009 16:27:14 GMT (18kb)

Title: Rabi Interferometry and Sensitive Measurement of the Casimir-Polder

Force with Ultra-Cold Gases

Authors: Jan Chwede\'nczuk, Luca Pezz\'e, Francesco Piazza and Augusto Smerzi

Categories: quant-ph

\\

We show that Rabi oscillations of a degenerate fermionic or bosonic gas

trapped in a double-well potential can be exploited for the interferometric

measurement of external forces at micrometer length scales. The Rabi

interferometer is less sensitive, but easier to implement, than the

Mach-Zehnder since it does not require dynamical beam-splitting/recombination

processes. As an application we propose a measurement of the Casimir-Polder

force acting between the atoms and a dielectric surface. We find that even if

the interferometer is fed with a coherent state of relatively small number of

atoms, and in the presence of realistic experimental noise, the force can be

measured with a sensitivity sufficient to discriminate between thermal and

zero-temperature regimes of the Casimir-Polder potential. Higher sensitivities

can be reached with spin squeezed states.

\\ ( http://arxiv.org/abs/0909.0705 , 18kb)

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Some obscure but interesting ones:

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\\

arXiv:0908.4464 (*cross-listing*)

Date: Mon, 31 Aug 2009 06:27:46 GMT (1898kb)

Title: The eel-like robot

Authors: Fr\'ed\'eric Boyer (IRCCyN), Damien Chablat (IRCCyN), Philippe Lemoine

(IRCCyN), Philippe Wenger (IRCCyN)

Categories: cs.RO physics.class-ph

Journal-ref: ASME Design Engineering Technical Conferences, San Diego : United

States (2009)

\\

The aim of this project is to design, study and build an "eel-like robot"

prototype able to swim in three dimensions. The study is based on the analysis

of eel swimming and results in the realization of a prototype with 12

vertebrae, a skin and a head with two fins. To reach these objectives, a

multidisciplinary group of teams and laboratories has been formed in the

framework of two French projects.

\\ ( http://arxiv.org/abs/0908.4464 , 1898kb)

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\\

arXiv:0909.0084

Date: Tue, 1 Sep 2009 04:07:41 GMT (377kb)

Title: Revisiting Pollock's Drip Paintings

Authors: Katherine Jones-Smith, Harsh Mathur

Categories: physics.soc-ph

Comments: Appeared in Nature Nov.2006. Previously unavailable on arxiv. Figures

here are low resolution version

Journal-ref: Nature 444, E9-E10 (30 November 2006)

\\

We investigate the contentions that Jackson Pollock's drip paintings are

fractals produced by the artist's Levy distributed motion and that fractal

analysis may be used to authenticate works of uncertain provenance[1-5]. We

find that the paintings exhibit fractal characteristics over too small a range

to be usefully considered as fractal; their limited fractal characteristics are

easily generated without Levy motion, both by freehand drawing and gaussian

random motion. Several problems must therefore be addressed before fractal

analysis can be used to authenticate paintings.

\\ ( http://arxiv.org/abs/0909.0084 , 377kb)

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\\

arXiv:0908.4349 (*cross-listing*)

Date: Sat, 29 Aug 2009 17:28:06 GMT (197kb)

Title: Scientific Understanding and the Risk from Extreme Space Weather

Authors: Mike Hapgood

Categories: physics.space-ph physics.plasm-ph physics.soc-ph

Comments: Submitted to Advances in Space Research

\\

Like all natural hazards, space weather exhibits occasional extreme events

over timescales of decades to centuries. Historical events provoked much

interest but had little economic impact. However, the widespread adoption of

advanced technological infrastructures over the past fifty years gives these

events the potential to disrupt those infrastructures - and thus create

profound economic and societal impact. However, like all extreme hazards, such

events are rare, so we have limited data on which to build our understanding of

the events. Many other natural hazards (e.g. flash floods) are highly

localised, so statistically significant datasets can be assembled by combining

data from independent instances of the hazard recorded over a few decades. But

we have a single instance of space weather so we would have to make

observations for many centuries in order to build a statistically significant

dataset. Instead we must exploit our knowledge of solar-terrestrial physics to

find other ways to assess these risks. We discuss three alternative approaches:

(a) use of proxy data, (b) studies of other solar systems, and (c) use of

physics-based modelling. The proxy data approach is well-established as a

technique for assessing the long-term risk from radiation storms, but does not

yet provide any means to assess the risk from severe geomagnetic storms. This

latter risk is more suited to the other approaches. We need to develop and

expand techniques to monitoring key space weather features in other solar

systems. To make progress in modelling severe space weather, we need to focus

on the physics that controls severe geomagnetic storms, e.g. how can dayside

and tail reconnection be modulated to expand the region of open flux to envelop

mid-latitudes?

\\ ( http://arxiv.org/abs/0908.4349 , 197kb)

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The replacements:

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arXiv:0709.3740

replaced with revised version Fri, 28 Aug 2009 19:03:01 GMT (1273kb)

Title: Staggered-Vortex Superfluid of Ultracold Bosons in an Optical Lattice

Authors: Lih-King Lim, C. Morais Smith, Andreas Hemmerich

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

Comments: 4 pages, 4 figures

Journal-ref: Phys. Rev. Lett. 100, 130402 (2008)

\\ ( http://arxiv.org/abs/0709.3740 , 1273kb)

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\\

arXiv:0804.2600

replaced with revised version Fri, 28 Aug 2009 17:53:58 GMT (407kb)

Title: Correlation Effects in Ultracold Two-Dimensional Bose Gases

Authors: Lih-King Lim, C. Morais Smith, and H. T. C. Stoof

Categories: cond-mat.stat-mech

Comments: 11 pages, 12 figures

Journal-ref: Phys. Rev. A 78, 013634 (2008)

\\ ( http://arxiv.org/abs/0804.2600 , 407kb)

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\\

arXiv:0905.1281

replaced with revised version Fri, 28 Aug 2009 17:40:26 GMT (2517kb)

Title: Strongly Interacting Two-Dimensional Dirac Fermions

Authors: Lih-King Lim, Achilleas Lazarides, Andreas Hemmerich, and C. Morais

Smith

Categories: cond-mat.quant-gas cond-mat.supr-con

Comments: 4 pages, 3 figures

\\ ( http://arxiv.org/abs/0905.1281 , 2517kb)

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\\

arXiv:0902.2275

replaced with revised version Mon, 31 Aug 2009 11:31:34 GMT (443kb,D)

Title: Angular FFLO State in Cold Fermion Gases in Toroidal Trap

Authors: Youichi Yanase

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

Comments: Some discussions are added

\\ ( http://arxiv.org/abs/0902.2275 , 443kb)

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\\

arXiv:0908.3356

replaced with revised version Sun, 30 Aug 2009 11:42:49 GMT (1539kb)

Title: Quantum Information Approach to Rotating Bose-Einstein Condensate

Authors: Zhao Liu, Hongli Guo, Shu Chen and Heng Fan

Categories: cond-mat.quant-gas quant-ph

Comments: 4 pages, 6 figures, minimal changes are made

\\ ( http://arxiv.org/abs/0908.3356 , 1539kb)

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\\

arXiv:0904.0995

replaced with revised version Mon, 31 Aug 2009 02:06:35 GMT (1019kb)

Title: Drag force on an impurity below the superfluid critical velocity in a

quasi-one-dimensional Bose-Einstein condensate

Authors: Andrew G. Sykes, Matthew J. Davis, and David C. Roberts

Categories: cond-mat.quant-gas

Comments: 7 pages (including supplementary material)

Journal-ref: Phys. Rev. Lett. 103, 085302 (2009)

\\ ( http://arxiv.org/abs/0904.0995 , 1019kb)

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\\

arXiv:0904.2881

replaced with revised version Sat, 29 Aug 2009 17:48:50 GMT (1947kb)

Title: A supercritical superfluid and vortex unbinding following a quantum

quench

Authors: L. Mathey, A. Polkovnikov

Categories: cond-mat.quant-gas

Comments: 4 pages, 5 figures

\\ ( http://arxiv.org/abs/0904.2881 , 1947kb)

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\\

arXiv:0904.3738

replaced with revised version Mon, 31 Aug 2009 11:10:57 GMT (476kb)

Title: p-Wave Resonant Bose Gas: A Finite-Momentum Spinor Superfluid

Authors: Leo Radzihovsky, Sungsoo Choi

Categories: cond-mat.quant-gas cond-mat.other

Comments: updated version published in PRL, with minor typos corrected

Journal-ref: Phys. Rev. Lett. 103, 095302 (2009)

\\ ( http://arxiv.org/abs/0904.3738 , 476kb)

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\\

arXiv:0905.3420

replaced with revised version Mon, 31 Aug 2009 07:08:07 GMT (286kb)

Title: Photon wave function and zitterbewegung

Authors: Zhi-Yong Wang, Cai-Dong Xiong, Qi Qiu

Categories: quant-ph

Comments: 26 pages, no figure

\\ ( http://arxiv.org/abs/0905.3420 , 286kb)

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\\

arXiv:0908.0248

replaced with revised version Wed, 2 Sep 2009 07:59:51 GMT (147kb)

Title: Bose-Einstein condensation of alkaline earth atoms: $^{40}${Ca}

Authors: Sebastian Kraft, Felix Vogt, Oliver Appel, Fritz Riehle, and Uwe Sterr

Categories: cond-mat.quant-gas physics.atom-ph

\\ ( http://arxiv.org/abs/0908.0248 , 147kb)

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\\

arXiv:0810.1965

replaced with revised version Thu, 3 Sep 2009 17:54:37 GMT (183kb)

Title: Coherent Atom-Molecule Oscillations in a Bose-Fermi Mixture

Authors: M. L. Olsen, J. D. Perreault, T. D. Cumby, and D. S. Jin

Categories: cond-mat.other

Comments: 5 pages, 4 figures

Journal-ref: Phys. Rev. A 80, 030701(R) (2009)

\\ ( http://arxiv.org/abs/0810.1965 , 183kb)

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\\

arXiv:gr-qc/0506108 (*cross-listing*)

replaced with revised version Thu, 3 Sep 2009 09:31:20 GMT (18kb)

Title: Dark energy from quantum wave function collapse of dark matter

Authors: A. S. Majumdar, D. Home, S. Sinha

Categories: gr-qc quant-ph

Comments: 5 pages in Elsevier style to match with version published in Phys.

Lett. B

Journal-ref: Phys. Lett. B 679 (2009) 167

\\ ( http://arxiv.org/abs/gr-qc/0506108 , 18kb)

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Till next time,

Matt.

-- ========================================================================= Dr M. J. Davis, Associate Professor in Physics School of Mathematics and Physics, ph : +61 7 334 69824 The University of Queensland, fax : +61 7 336 51242 Brisbane, QLD 4072, mdavis_at_physics.uq.edu.au Australia. 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 ========================================================================= _______________________________________________ Matts-arxiv mailing list Matts-arxiv_at_lists.sps.uq.edu.auReceived on Fri Nov 20 2009 - 18:54:59 EST

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