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

Date: Thu, 28 Oct 2010 22:05:43 +1000

Date: Thu, 28 Oct 2010 22:05:43 +1000

Dear subscribers,

This week's selection was compiled by Jacopo Sabbatini, and contains 36 new

abstracts and 15 replacements.

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arXiv:1009.0555

Date: Thu, 2 Sep 2010 22:26:42 GMT (848kb)

Title: Anderson localization in Bose-Einstein condensates

Authors: Giovanni Modugno

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

Comments: 15 pages review, to appear in Reports on Progress in Physics

\\

The understanding of disordered quantum systems is still far from being

complete, despite many decades of research on a variety of physical systems. In

this review we discuss how Bose-Einstein condensates of ultracold atoms in

disordered potentials have opened a new window for studying fundamental

phenomena related to disorder. In particular, we point our attention to recent

experimental studies on Anderson localization and on the interplay of disorder

and weak interactions. These realize a very promising starting point for a

deeper understanding of the complex behaviour of interacting, disordered

systems.

\\ ( http://arxiv.org/abs/1009.0555 , 848kb)

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arXiv:1009.0587

Date: Fri, 3 Sep 2010 05:18:14 GMT (512kb,D)

Title: Feedback control of an interacting Bose-Einstein condensate using

phase-contrast imaging

Authors: Stuart S. Szigeti, Michael R. Hush, Andre R. R. Carvalho and Joseph J.

Hope

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

Comments: 12 pages, 5 figures

\\

The linewidth of an atom laser is limited by density fluctuations in the

Bose-Einstein condensate (BEC) from which the atom laser beam is outcoupled. In

this paper we show that a stable spatial mode for an interacting BEC can be

generated using a realistic control scheme that includes the effects of the

measurement backaction. This model extends the feedback theory, based on a

phase-contrast imaging setup, presented in \cite{Szigeti:2009}. In particular,

it is applicable to a BEC with large interatomic interactions and solves the

problem of inadequacy of the mean-field (coherent state) approximation by

utilising a fixed number state approximation. Our numerical analysis shows the

control to be more effective for a condensate with a large nonlinearity.

\\ ( http://arxiv.org/abs/1009.0587 , 512kb)

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arXiv:1009.0640 (*cross-listing*)

Date: Fri, 3 Sep 2010 11:57:34 GMT (151kb,D)

Title: Atomic Fock states by gradual trap reduction: from sudden to adiabatic

limits

Authors: D.Sokolovski, M.Pons, A.del Campo and J.G.Muga

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

\\

We investigate the possibility to form high fidelity atomic Fock states by

gradual reduction of a quasi one dimensional trap containing spin polarized

fermions or strongly interacting bosons in the Tonk-Girardeau regime. Making

the trap shallower and simultaneously squeezing it can lead to the preparation

of an ideal atomic Fock state as one approaches either the sudden or the

adiabatic limits. Nonetheless, the fidelity of the resulting state is shown to

exhibit a non-monotonic behaviour with the time scale in which the trapping

potential is changed.

\\ ( http://arxiv.org/abs/1009.0640 , 151kb)

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arXiv:1009.0653 (*cross-listing*)

Date: Fri, 3 Sep 2010 13:09:43 GMT (435kb)

Title: Non-Linear Dynamics of Continuously Measured Bose-Einstein Condensates

in One-Dimensional Harmonic Traps

Authors: T.Yu. Ivanova, M.S. Samoylova, D.A. Ivanov

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

Comments: 8 pages, 5 figures

\\

Continuous center-of-mass position measurements performed on an interacting

harmonically trapped Bose-gas are considered. Using both semi-analytical

mean-field approach and completely quantum numerical technique based on

positive P-representation, it is demonstrated that the atomic delocalization

due to the measurement back action is smaller for a strongly interacting gas.

The numerically calculated second-order correlation functions demonstrate

appearance of atomic bunching as a result of the center-of-mass measurement.

Though being rather small the bunching is present also for strongly interacting

gas which is in contrast with the case of unperturbed gas. The performed

analysis allows to speculate that for relatively strong interactions the size

of atomic bunches can become smaller than the initial cloud size resulting in a

sort of squeezing effect.

\\ ( http://arxiv.org/abs/1009.0653 , 435kb)

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arXiv:1009.0675

Date: Fri, 3 Sep 2010 14:04:27 GMT (623kb)

Title: Polaronic slowing of fermionic impurities in lattice Bose-Fermi mixtures

Authors: Antonio Privitera and Walter Hofstetter

Categories: cond-mat.quant-gas

Comments: 13 pages, 5 figures

\\

We generalize the application of small polaron theory to ultracold gases of

Ref. [\onlinecite{jaksch_njp1}] to the case of Bose-Fermi mixtures, where both

components are loaded into an optical lattice. In a suitable range of

parameters, the mixture can be described within a Bogoliubov approach in the

presence of fermionic (dynamic) impurities and an effective description in

terms of polarons applies. In the dilute limit of the slow impurity regime, the

hopping of fermionic particles is exponentially renormalized due to polaron

formation, regardless of the sign of the Bose-Fermi interaction. This should

lead to clear experimental signatures of polaronic effects, once the regime of

interest is reached. The validity of our approach is analyzed in the light of

currently available experiments. We provide results for the hopping

renormalization factor for different values of temperature, density and

Bose-Fermi interaction for three-dimensional $^{87}\rm{Rb}-^{40}\rm{K}$

mixtures in optical lattice.

\\ ( http://arxiv.org/abs/1009.0675 , 623kb)

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arXiv:1009.0759 (*cross-listing*)

Date: Fri, 3 Sep 2010 20:03:31 GMT (136kb)

Title: Momentum-space engineering of gaseous Bose-Einstein condensates

Authors: Mark Edwards, Brandon Benton, Jeffrey Heward, Charles W. Clark

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

Comments: 13 pages, 4 figures

\\

We show how the momentum distribution of gaseous Bose-Einstein condensates

can be shaped by applying a sequence of standing--wave laser pulses. We present

a theory of the effect of such a pulse sequence on the condensate wave function

in momentum space. We generalize the previous result to the case of N pulses of

arbitrary intensity separated by arbitrary intervals and show how these

parameters can be engineered to produce a desired final momentum distribution.

We find that several momentum distributions, important in atom interferometry

applications, can be engineered with high fidelity with two or three pulses.

\\ ( http://arxiv.org/abs/1009.0759 , 136kb)

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arXiv:1009.0791

Date: Sat, 4 Sep 2010 00:16:27 GMT (416kb)

Title: Isentropic Curves at Magnetic Phase Transitions

Authors: J.D. Cone, A. Zujev and R.T. Scalettar

Categories: cond-mat.quant-gas

\\

Experiments on cold atom systems in which a lattice potential is ramped up on

a confined cloud have raised intriguing questions about how the temperature

varies along isentropic curves, and how these curves intersect features in the

phase diagram. In this paper, we study the isentropic curves of two models of

magnetic phase transitions- the classical Blume-Capel Model (BCM) and the Fermi

Hubbard Model (FHM). Both Mean Field Theory (MFT) and Monte Carlo (MC) methods

are used. The isentropic curves of the BCM generally run parallel to the phase

boundary in the Ising regime of low vacancy density, but intersect the phase

boundary when the magnetic transition is mainly driven by a proliferation of

vacancies. Adiabatic heating occurs in moving away from the phase boundary. The

isentropes of the half-filled FHM have a relatively simple structure, running

parallel to the temperature axis in the paramagnetic phase, and then curving

upwards as the antiferromagnetic transition occurs. However, in the doped case,

where two magnetic phase boundaries are crossed, the isentrope topology is

considerably more complex.

\\ ( http://arxiv.org/abs/1009.0791 , 416kb)

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arXiv:1009.0823

Date: Sat, 4 Sep 2010 10:56:58 GMT (829kb,D)

Title: Cascade of vortex loops initiated by a single reconnection of quantum

vortices

Authors: Miron Kursa, Konrad Bajer and Tomasz Lipniacki

Categories: cond-mat.other physics.flu-dyn

Comments: 9 pages, 5 figures, submitted to APS (preprint)

MSC-class: 76A25

\\

We demonstrate that a single reconnection of two quantum vortices can lead to

creation of a cascade of vortex rings. Our analysis, motivated by the

analytical solution in LIA, involves high-resolution Biot-Savart and

Gross-Pitaevskii simulations. The latter showed that the rings cascade starts

on the atomic scale, with rings diameters orders of magnitude smaller than the

characteristic line spacing in the tangle. So created vortex rings may

penetrate the tangle and annihilate on the boundaries. This provides an

efficient mechanism of the vortex tangle decay in very low temperatures.

\\ ( http://arxiv.org/abs/1009.0823 , 829kb)

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arXiv:1009.0926

Date: Sun, 5 Sep 2010 16:03:54 GMT (159kb)

Title: Study of Efimov physics in two nuclear-spin sublevels of 7Li

Authors: Noam Gross, Zav Shotan, Olga Machtey, Servaas Kokkelmans and Lev

Khaykovich

Categories: cond-mat.quant-gas

Comments: 15 pages, 7 figures

\\

Efimov physics in two nuclear-spin sublevels of bosonic lithium is studied

and it is shown that the positions and widths of recombination minima and

Efimov resonances are identical for both states within the experimental errors

which indicates that the short-range physics is nuclear-spin independent. We

also find that the Efimov features are universally related across Feshbach

resonances. These results crucially depend on careful mapping between the

scattering length and the applied magnetic field which we achieve by

characterization of the two broad Feshbach resonances in the different states

by means of rf-spectroscopy of weakly bound molecules. By fitting the binding

energies numerically with a coupled channels calculation we precisely determine

the absolute positions of the Feshbach resonances and the values of the singlet

and triplet scattering lengths.

\\ ( http://arxiv.org/abs/1009.0926 , 159kb)

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arXiv:1009.0951

Date: Sun, 5 Sep 2010 21:13:46 GMT (174kb)

Title: Breakdown of universality in few-boson systems

Authors: A. Deltuva and R. Lazauskas

Categories: physics.atom-ph nucl-th

Journal-ref: Phys. Rev. A 82, 012705 (2010)

DOI: 10.1103/PhysRevA.82.012705

\\

We develop a series of resonant short-range two-boson potentials reproducing

the same two-body low-energy observables and apply them in three- and four-body

calculations. We demonstrate that the universal behavior predicted by effective

field theory may be strongly violated and analyze the conditions for this

phenomenon.

\\ ( http://arxiv.org/abs/1009.0951 , 174kb)

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arXiv:1009.0975

Date: Mon, 6 Sep 2010 07:14:07 GMT (641kb)

Title: Breathing Oscillations in Bose - Fermi Mixing Gases with Yb atoms in the

Largely Prolate Deformed Traps

Authors: Tomoyuki Maruyama, Hiroyuki Yabu

Categories: cond-mat.quant-gas

Comments: 27 pages, 12 figures

\\

We study the breathing oscillations in bose-fermi mixtures with Yb isotopes

in the largely prolate deformed trap, which are realized by Kyoto group. We

choose the three combinations of the Yb isotopes, Yb170-Yb171, Yb170-Yb173 and

Yb174-Yb173, whose boson-fermion interactions are weakly repulsive, strongly

attractive and strongly repulsive. The collective oscillations in the deformed

trap are calculated in the dynamical time-development approach, which is

formulated with the time-dependent Gross-Pitaevskii and the Vlasov equations.

We analyze the results in the time-development approach with the intrinsic

oscillation modes of the deformed system, which are obtained using the scaling

method, and show that the damping and forced-oscillation effects of the

intrinsic modes give time-variation of oscillations, especially, in the fermion

transverse mode.

\\ ( http://arxiv.org/abs/1009.0975 , 641kb)

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arXiv:1009.0995

Date: Mon, 6 Sep 2010 09:14:10 GMT (11kb)

Title: Squeezing Inequalities and Entanglement for Identical Particles

Authors: F. Benatti, R. Floreanini, U. Marzolino

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

Comments: 13 pages, LaTex

\\

By identifying non-local effects in systems of identical Bosonic qubits

through correlations of their commuting observables, we show that entanglement

is not necessary to violate certain squeezing inequalities that hold for

distinguishable qubits and that spin squeezing may not be necessary to achieve

sub-shot noise accuracies in ultra-cold atom interferometry.

\\ ( http://arxiv.org/abs/1009.0995 , 11kb)

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arXiv:1009.1072

Date: Mon, 6 Sep 2010 14:36:02 GMT (433kb,D)

Title: Supersolid phases of dipolar bosons in optical lattices with a staggered

flux

Authors: O. Tieleman, A. Lazarides, and C. Morais Smith

Categories: cond-mat.quant-gas

Comments: 10+ pages

\\

We present the theoretical mean-field zero-temperature phase diagram of a

Bose-Einstein condensate (BEC) with dipolar interactions loaded into an optical

lattice with a staggered flux. Apart from uniform superfluid, checkerboard

supersolid and striped supersolid phases, we identify several supersolid phases

with staggered vortices, which can be seen as combinations of supersolid phases

found in earlier work on dipolar BECs and a staggered-vortex phase found for

bosons in optical lattices with staggered flux. By allowing for different

phases and densities on each of the four sites of the elementary plaquette,

more complex phase patterns are found.

\\ ( http://arxiv.org/abs/1009.1072 , 433kb)

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arXiv:1009.1073 (*cross-listing*)

Date: Mon, 6 Sep 2010 14:43:09 GMT (505kb)

Title: Stochastic quantum dynamics in 1D and lattice systems

Authors: J. Ruostekoski and A. D. Martin

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

Comments: Chapter in "Non-Equilibrium Quantum Gases at Finite Temperatures",

ed. M. Davis, S. Gardiner, N. Nygaard, N. Proukakis, and M. Szymanska (World

Scientific, 2010)

\\

We show that stochastic phase-space methods within the truncated Wigner

approximation can be used to solve non-equilibrium dynamics of bosonic atoms in

1d traps. We consider systems both with and without an optical lattice and

address different approximations in stochastic synthesization of quantum

statistical correlations of the initial atomic field operator. We also present

a numerically efficient projection method for analyzing correlation functions

of the simulation results. Physical examples demonstrate non-equilibrium

quantum dynamics of solitons and atom number squeezing in optical lattices in

which case we, e.g., numerically track the soliton coordinates and calculate

quantum mechanical expectation values and uncertainties for the position of the

soliton.

\\ ( http://arxiv.org/abs/1009.1073 , 505kb)

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arXiv:1009.1295 (*cross-listing*)

Date: Tue, 7 Sep 2010 13:59:58 GMT (32kb)

Title: Efimov physics in bosonic atom-trimer scattering

Authors: A. Deltuva

Categories: physics.atm-clus cond-mat.quant-gas nucl-th

Comments: 4 pages, 4 figures, 3 tables

\\

Bosonic atom-trimer scattering is studied in the unitary limit using

momentum-space equations for four-particle transition operators. The impact of

the Efimov effect on the atom-trimer scattering observables is explored and a

number of universal relations is established. Positions and widths of tetramer

resonances are determined.

\\ ( http://arxiv.org/abs/1009.1295 , 32kb)

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arXiv:1009.1313

Date: Tue, 7 Sep 2010 14:46:10 GMT (33kb)

Title: Bose-Hubbard model with occupation dependent parameters

Authors: Omjyoti Dutta, Andre Eckardt, Philipp Hauke, Boris Malomed, and Maciej

Lewenstein

Categories: cond-mat.quant-gas

Comments: 14 pages, 4 figures

\\

We study the ground-state properties of ultracold bosons in an optical

lattice in the regime of strong interactions. The system is described by a

non-standard Bose-Hubbard model with both occupation-dependent tunneling and

on-site interaction parameters. We find that for sufficiently strong coupling,

the system features a phase-transition from a Mott insulator with one particle

per site to a superfluid of spatially extended particle pairs living on top of

the Mott background. Increasing the interaction further, a superfluid of

particle pairs localized on a single site (rather than being extended) on top

of the Mott background appears. This happens at the same time when the

Mott-insulator phase with 2 particles per site is destroyed completely by

particle-hole fluctuations for arbitrary small tunneling. In another regime,

characterized by weak interaction, but high occupation numbers, we observe a

dynamical instability in the superfluid excitation spectrum. The new ground

state is a superfluid, forming a 2D slab, localized along one spatial direction

that is spontaneously chosen.

\\ ( http://arxiv.org/abs/1009.1313 , 33kb)

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arXiv:1009.1358 (*cross-listing*)

Date: Tue, 7 Sep 2010 18:52:26 GMT (2171kb,D)

Title: Combined quantum state preparation and laser cooling of a continuous

beam of cold atoms

Authors: Gianni Di Domenico, Laurent Devenoges, Claire Dumas, Pierre Thomann

Categories: physics.atom-ph quant-ph

\\

We use two-laser optical pumping on a continuous atomic fountain in order to

prepare cold cesium atoms in the same quantum ground state. A first laser

excites the F=4 ground state to pump the atoms toward F=3 while a second

pi-polarized laser excites the F=3 -> F'=3 transition of the D2 line to produce

Zeeman pumping toward m=0. To avoid trap states, we implement the first laser

in a 2D optical lattice geometry, thereby creating polarization gradients. This

configuration has the advantage of simultaneously producing Sisyphus cooling

when the optical lattice laser is tuned between the F=4 -> F'=4 and F=4 -> F'=5

transitions of the D2 line, which is important to remove the heat produced by

optical pumping. Detuning the frequency of the second pi-polarized laser

reveals the action of a new mechanism improving both laser cooling and state

preparation efficiency. A physical interpretation of this mechanism is

discussed.

\\ ( http://arxiv.org/abs/1009.1358 , 2171kb)

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arXiv:1009.1366 (*cross-listing*)

Date: Tue, 7 Sep 2010 19:03:17 GMT (10kb)

Title: Mapping between Hamiltonians with attractive and repulsive potentials on

a lattice

Authors: Yogesh N. Joglekar

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

Comments: 6 pages, 1 figure

\\

Through a simple and exact analytical derivation, we show that for a particle

on a lattice, there is a one-to-one correspondence between the spectra in the

presence of an attractive potential $\hat{V}$ and its repulsive counterpart

$-\hat{V}$. For a Hermitian potential, this result implies that the number of

localized states is the same in both, attractive and repulsive, cases although

these states occur above (below) the band-continnum for the repulsive

(attractive) case. For a $\mP\mT$-symmetric potential that is odd under parity,

our result implies that in the $\mP\mT$-unbroken phase, the energy eigenvalues

are symmetric around zero, and that the corresponding eigenfunctions are

closely related to each other.

\\ ( http://arxiv.org/abs/1009.1366 , 10kb)

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arXiv:1009.1389

Date: Tue, 7 Sep 2010 20:03:16 GMT (668kb)

Title: Bogoliubov theory of interacting bosons on a lattice in a synthetic

magnetic field

Authors: Stephen Powell, Ryan Barnett, Rajdeep Sensarma, Sankar Das Sarma

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

Comments: 22 pages, 7 figures

\\

We consider theoretically the problem of an artificial gauge potential

applied to a cold atomic system of interacting neutral bosons in a

tight-binding optical lattice. Using the Bose-Hubbard model, we show that an

effective magnetic field leads to superfluid phases with simultaneous spatial

order, which we analyze using Bogoliubov theory. This gives a consistent

expansion in terms of quantum and thermal fluctuations, in which the lowest

order gives a Gross-Pitaevskii equation determining the condensate

configuration. We apply an analysis based on the magnetic symmetry group to

show how the spatial structure of this configuration depends on commensuration

between the magnetic field and the lattice. Higher orders describe the

quasiparticle excitations, whose spectrum combines the intricacy the Hofstadter

butterfly with the characteristic features of the superfluid phase. We use the

depletion of the condensate to determine the range of validity of our

approximations and also to find an estimate for the onset of the Mott insulator

phase. Our theory provides concrete experimental predictions, for both

time-of-flight imagery and Bragg spectroscopy.

\\ ( http://arxiv.org/abs/1009.1389 , 668kb)

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arXiv:1009.1398

Date: Tue, 7 Sep 2010 20:29:24 GMT (124kb)

Title: Three-sublattice ordering of the SU(3) Heisenberg model of three-flavor

fermions on the square and cubic lattices

Authors: Tamas A. Toth, Andreas M. Laeuchli, Frederic Mila, and Karlo Penc

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

Comments: 4 pages, 3 figures

\\

Combining a semi-classical analysis with exact diagonalizations, we show that

the ground state of the SU(3) Heisenberg model on the square lattice develops

three-sublattice long-range order. This surprising pattern for a bipartite

lattice with only nearest-neighbor interactions is shown to be the consequence

of a subtle quantum order-by-disorder mechanism. By contrast, thermal

fluctuations favor two-sublattice configurations via entropic selection. These

results are shown to extend to the cubic lattice, and experimental implications

for the Mott-insulating states of three-flavor fermionic atoms in optical

lattices are discussed.

\\ ( http://arxiv.org/abs/1009.1398 , 124kb)

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arXiv:1009.1409

Date: Tue, 7 Sep 2010 21:31:03 GMT (174kb)

Title: Itinerant ferromagnetism in a Fermi gas with contact interaction:

Magnetic properties in a dilute Hubbard model

Authors: Chia-Chen Chang, Shiwei Zhang, David M. Ceperley

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

Comments: 4+ pages, 4 figures

\\

Ground state properties of the repulsive Hubbard model on a cubic lattice are

investigated by means of the auxiliary-field quantum Monte Carlo method. We

focus on low-density systems with varying on-site interaction $U/t$, as a model

relevant to recent experiments on itinerant ferromagnetism in a dilute Fermi

gas with contact interaction. Twist-average boundary conditions are used to

eliminate open-shell effects and large lattice sizes are studied to reduce

finite-size effects. The sign problem is controlled by a generalized

constrained path approximation. We find no ferromagnetic phase transition in

this model. The ground-state correlations are consistent with those of a

paramagnetic Fermi liquid.

\\ ( http://arxiv.org/abs/1009.1409 , 174kb)

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arXiv:1009.1420

Date: Tue, 7 Sep 2010 23:01:03 GMT (36kb)

Title: Supersolidity in electron-hole bilayers with a large density imbalance

Authors: Meera M. Parish, Francesca M. Marchetti, Peter B. Littlewood

Categories: cond-mat.str-el

Comments: 4+ pages, 3 figures

\\

We consider an electron-hole bilayer in the limit of extreme density

imbalance, where we have a single particle in one layer interacting

attractively with a Fermi liquid in the other parallel layer. Using an

appropriate variational wave function for the dressed exciton, we provide

strong evidence for the existence of the Fulde-Ferrell-Larkin-Ovchninnikov

(FFLO) phase in electron-hole bilayers with a large density imbalance.

Furthermore, within this unusual limit of FFLO, we find that a dilute gas of

minority particles forms excitons that condense into a two-dimensional

"supersolid".

\\ ( http://arxiv.org/abs/1009.1420 , 36kb)

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arXiv:1009.1465

Date: Wed, 8 Sep 2010 07:35:08 GMT (1109kb)

Title: Phase diagram of spin-1/2 bosons in one-dimensional optical lattice

Authors: L. de Forges de Parny, M. Traynard, F. H\'ebert, V.G. Rousseau, R.T.

Scalettar, and G.G. Batrouni

Categories: cond-mat.stat-mech

\\

Systems of two coupled bosonic species are studied using Mean Field Theory

and Quantum Monte Carlo. The phase diagram is characterized both based on the

mobility of the particles (Mott insulating or superfluid) and whether or not

the system is magnetic (different populations for the two species). The phase

diagram is shown to be population balanced for negative spin-dependent

interactions, regardless of whether it is insulating or superfluid. For

positive spin-dependent interactions, the superfluid phase is always polarized,

the two populations are imbalanced. On the other hand, the Mott insulating

phase with even commensurate filling has balanced populations while the odd

commensurate filling Mott phase has balanced populations at very strong

interaction and polarizes as the interaction gets weaker while still in the

Mott phase.

\\ ( http://arxiv.org/abs/1009.1465 , 1109kb)

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arXiv:1009.1471

Date: Wed, 8 Sep 2010 08:02:06 GMT (310kb)

Title: Internal Josephson Oscillations for Distinct Momenta Bose-Einstein

Condensates

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

Categories: cond-mat.quant-gas

Comments: 4 pages, 3 figures

\\

The internal Josephson oscillations between an atomic Bose-Einstein

condensate (BEC) and a molecular one are studied for atoms in a square optical

lattice subjected to a staggered gauge field. The system is described by a

Bose-Hubbard model with complex and anisotropic hopping parameters, which are

different for each species, atoms and molecules. When the flux per plaquette

for each species is small, the system oscillates between two conventional

zero-momentum condensates. However, there is a regime of parameters where

Josephson oscillations between a vortex-carrying atomic condensate (finite

momentum BEC) and a conventional zero-momentum molecular condensate may be

realized. The experimental observation of the oscillations between these

qualitatively distinct BEC's is possible with state of the art Ramsey

interference techniques.

\\ ( http://arxiv.org/abs/1009.1471 , 310kb)

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arXiv:1009.1482

Date: Wed, 8 Sep 2010 08:55:41 GMT (941kb)

Title: Two-boson Correlations in Various One-dimensional Traps

Authors: Anna Okopinska, Przemyslaw Koscik

Categories: quant-ph

Comments: 5 pages, 3 figures

Journal-ref: Few-Body System,Volume 45, Numbers 2-4, 223-226 2009

\\

A one-dimensional system of two trapped bosons which interact through a

contact potential is studied using the optimized configuration interaction

method. The rapid convergence of the method is demonstrated for trapping

potentials of convex and non-convex shapes. The energy spectra, as well as

natural orbitals and their occupation numbers are determined in function of the

inter-boson interaction strength. Entanglement characteristics are discussed in

dependence on the shape of the confining potential.

\\ ( http://arxiv.org/abs/1009.1482 , 941kb)

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arXiv:1009.1511

Date: Wed, 8 Sep 2010 12:10:08 GMT (91kb)

Title: The second critical point for the Perfect Bose gas in

quasi-one-dimensional traps

Authors: Mathieu Beau (CPT), Valentin A. Zagrebnov (CPT)

Categories: cond-mat.quant-gas

\\

We present a new model of quasi-one-dimensional trap with some unknown

physical predictions about a second transition, including about a change in

fractions of condensed coherence lengths due to the existence of a second

critical temperature Tm < Tc. If this physical model is acceptable, we want to

challenge experimental physicists in this regard.

\\ ( http://arxiv.org/abs/1009.1511 , 91kb)

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arXiv:1009.1552 (*cross-listing*)

Date: Wed, 8 Sep 2010 14:44:33 GMT (58kb)

Title: Simulation of gauge transformations on systems of ultracold atoms

Authors: O. Boada, A. Celi and J.I. Latorre

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

Comments: 14 pages, 6 figures

\\

We show that gauge transformations can be simulated on systems of ultracold

atoms. We discuss observables that are invariant under these gauge

transformations and compute them using a tensor network ansatz that escapes the

phase problem. We determine that the Mott-insulator-to-superfluid critical

point is monotonically shifted as the induced magnetic flux increases. This

result is stable against the inclusion of a small amount of entanglement in the

variational ansatz.

\\ ( http://arxiv.org/abs/1009.1552 , 58kb)

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arXiv:1009.1574

Date: Wed, 8 Sep 2010 16:02:27 GMT (1253kb)

Title: Theoretical confirmation of Feynman's hypothesis on the creation of

circular vortices in Bose-Einstein condensates: III

Authors: E. Infeld, A. Senatorski and A. A. Skorupski

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

Comments: 10 pages, 7 figures

\\

In two preceding papers (Infeld and Senatorski 2003 J. Phys.: Condens. Matter

15 5865, and Senatorski and Infeld 2004 J. Phys.: Condens. Matter 16 6589) we

confirmed Feynman's hypothesis on how circular vortices can be created from

oppositely polarized pairs of linear vortices (first paper), and then gave

examples of the creation of several different circular vortices from one linear

pair (second paper). Here in part III, we give two classes of examples of how

the vortices can interact. The first confirms the intuition that the

reconnection processes which join two interacting vortex lines into one,

practically do not occur. The second shows that new circular vortices can also

be created from pairs of oppositely polarized coaxial circular vortices. This

seems to contradict the results for such pairs given in Koplik and Levine 1996

Phys. Rev. Lett. 76 4745.

\\ ( http://arxiv.org/abs/1009.1574 , 1253kb)

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\\

arXiv:1009.1599 (*cross-listing*)

Date: Wed, 8 Sep 2010 17:55:06 GMT (398kb)

Title: Persistent currents in Bose gases confined in annular traps

Authors: S. Bargi, F. Malet, G. M. Kavoulakis, S. M. Reimann

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

Comments: 6 pages, 4 figures

\\

We examine the problem of stability of persistent currents in a mixture of

two Bose gases trapped in an annular potential. We evaluate the critical

coupling for metastability in the transition from quasi-one to two-dimensional

motion. We also evaluate the critical coupling for metastability in a mixture

of two species as function of the population imbalance. The stability of the

currents is shown to be sensitive to the deviation from one-dimensional motion.

\\ ( http://arxiv.org/abs/1009.1599 , 398kb)

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\\

arXiv:1009.1646

Date: Wed, 8 Sep 2010 20:34:03 GMT (280kb,D)

Title: Do Quenched Spinor Condensates Thermalize?

Authors: Ryan Barnett, Anatoli Polkovnikov, and Mukund Vengalattore

Categories: cond-mat.quant-gas

Comments: 4 pages, 3 figures

\\

Motivated by recent experiments, we consider the dynamics of spin-one spinor

condensates after a quantum quench from the polar to ferromagnetic state from

varying the quadratic Zeeman field, $q$. We apply the Truncated Wigner

Approximation (TWA) to the spinor system with all spatial and spin degrees of

freedom. For short times, we find full agreement with the linearized Bogoliubov

analysis. For longer times, where the Bogoliubov theory fails, we find that the

system reaches a quasi-steady state. We compute the Bogoliubov spectrum about

the ferromagnetic state with finite $q$ and show that the resulting finite

temperature correlation functions grossly disagree with the full TWA results,

thus indicating that the system does not thermalize even over very long time

scales. We attribute this to the presence of topological defects (i.e. spin

vortices) which prevent the relaxation to the ground state over experimentally

relevant time scales.

\\ ( http://arxiv.org/abs/1009.1646 , 280kb)

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\\

arXiv:1009.1671

Date: Thu, 9 Sep 2010 02:08:49 GMT (1280kb)

Title: Hydrodynamic equation of a spinor dipolar Bose-Einstein condensate

Authors: Kazue Kudo and Yuki Kawaguchi

Categories: cond-mat.quant-gas

Comments: 13 pages, 5 figures

\\

We introduce equations of motion for spin dynamics in a ferromagnetic

Bose-Einstein condensate with magnetic dipole-dipole interaction, written using

a vector expressing the superfluid velocity and a complex scalar describing the

magnetization. This simple hydrodynamical description affords a straightforward

approach by which to investigate the spin dynamics of the condensate. To

demonstrate the advantages of the description, we illustrate dynamical

instability and magnetic fluctuation preference, which are expressed in

analytical forms.

\\ ( http://arxiv.org/abs/1009.1671 , 1280kb)

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\\

arXiv:1009.1696

Date: Thu, 9 Sep 2010 07:35:56 GMT (1318kb)

Title: Equilibrium Properties of Trapped Dipolar Gases at Finite Temperatures

Authors: Yuki Endo, Takahiko Miyakawa and Tetsuro Nikuni

Categories: cond-mat.other

Comments: 14 pages, 14 figures

\\

We study the equilibrium properties of dipolar Bose and Fermi gases at finite

temperatures. We recently developed a variational ansatz for the phase-space

distribution function of a dipolar Fermi gas at finite temperatures. We extend

the variational formalism to a Bose gas and discuss the effect of dipolar

interactions with different statistics on the thermal equilibrium, with

particular emphasis on the deformation in momentum space. We examine the

stability of the system by varying the temperature, trap aspect ratio and the

dipole moment. In addition, we discuss how deformation in both real and

momentum space can be observed in the high-temperature regime, which is

relevant for the current experiments at JILA [Ni et al. Science 322, 231

(2008)] and at University of Tokyo [Aikawa et al. New. J. Phys. 11, 055035

(2009)].

\\ ( http://arxiv.org/abs/1009.1696 , 1318kb)

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\\

arXiv:1009.1701

Date: Thu, 9 Sep 2010 07:50:28 GMT (333kb)

Title: Bose-Einstein condensation of 86Sr

Authors: Simon Stellmer, Meng Khoon Tey, Rudolf Grimm, Florian Schreck

Categories: cond-mat.quant-gas

Comments: 4 pages, 3 figures

\\

We report on the attainment of Bose-Einstein condensation of 86Sr. This

isotope has a scattering length of about +800 a0 and thus suffers from fast

three-body losses. To avoid detrimental atom loss, evaporative cooling is

performed at low densities around 3x10^12 cm^-3 in a large volume optical

dipole trap. We obtain almost pure condensates of 5x10^3 atoms.

\\ ( http://arxiv.org/abs/1009.1701 , 333kb)

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\\

arXiv:1009.1740

Date: Thu, 9 Sep 2010 11:24:21 GMT (4360kb)

Title: Crossover between Kelvin-Helmholtz and counter-superflow instabilities

in two-component Bose-Einstein condensates

Authors: Naoya Suzuki, Hiromitsu Takeuchi, Kenichi Kasamatsu, Makoto Tsubota,

Hiroki Saito

Categories: cond-mat.quant-gas

Comments: 10 pages, 9 figures

\\

Dynamical instabilities at the interface between two Bose--Einstein

condensates that are moving relative to each other are investigated using

mean-field and Bogoliubov analyses. Kelvin--Helmholtz instability is dominant

when the interface thickness is much smaller than the wavelength of the

unstable interface mode, whereas the counter-superflow instability becomes

dominant in the opposite case. These instabilities emerge not only in an

immiscible system but also in a miscible system where an interface is produced

by external potential. Dynamics caused by these instabilities are numerically

demonstrated in rotating trapped condensates.

\\ ( http://arxiv.org/abs/1009.1740 , 4360kb)

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\\

arXiv:1009.1776

Date: Thu, 9 Sep 2010 13:33:09 GMT (5708kb)

Title: Multi-band and nonlinear hopping corrections to the 1D Bose-Fermi

Hubbard model

Authors: Alexander Mering and Michael Fleischhauer

Categories: cond-mat.quant-gas

Comments: 10 pages, 4 figures, submitted to PRA

\\

Recent experiments revealed the importance of higher-band effects for the

Mott insulator -- superfluid transition of ultracold bosonic atoms or mixtures

of bosons and fermions in deep optical lattices [Best \emph{et al.}, PRL

\textbf{102}, 030408 (2009); Will \emph{et al.}, Nature \textbf{465}, 197

(2010)]. In the present work, we derive an effective lowest-band Hamiltonian in

1D that generalizes the standard Bose-Fermi-Hubbard model, taking these effects

into account within an adiabatic elimination scheme of virtual transitions to

higher bands. It also accounts for nonlinear corrections of the tunneling

amplitudes mediated by interspecies interactions within the first band only. It

is shown that a correct description of the lattice states in terms of the

bare-lattice Wannier functions rather than approximations such as harmonic

oscillator states is essential. In contrast to self-consistent treatments of

effective lattice wavefunctions, the present approach shows a reduction of the

superfluid phase for both attractive and repulsive interactions between bosons

and fermions.

\\ ( http://arxiv.org/abs/1009.1776 , 5708kb)

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\\

arXiv:1009.1787

Date: Thu, 9 Sep 2010 14:09:30 GMT (44kb)

Title: On the thermodynamics of classical micro-canonical systems

Authors: Maarten Baeten and Jan Naudts

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

\\

We study the configurational probability distribution of a mono-atomic gas

with a finite number of particles N in the micro-canonical ensemble. We give

two arguments why the thermodynamic entropy of the configurational subsystem

involves Renyi's entropy function rather than that of Tsallis. The first

argument is that the temperature of the configurational subsystem is equal to

that of the kinetic subsystem. The second argument is that the instability of

the pendulum, which occurs for energies close to the rotation threshold, is

correctly reproduced.

\\ ( http://arxiv.org/abs/1009.1787 , 44kb)

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The replacements:

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\\

arXiv:1007.4038 (*cross-listing*)

replaced with revised version Thu, 2 Sep 2010 22:40:30 GMT (4194kb)

Title: Robust Mesoscopic Superposition of Strongly Correlated Ultracold Atoms

Authors: David W. Hallwood, Thomas Ernst, Joachim Brand

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

Comments: 4 pages, 3 figures

\\ ( http://arxiv.org/abs/1007.4038 , 4194kb)

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\\

arXiv:1008.4732

replaced with revised version Fri, 3 Sep 2010 07:16:11 GMT (1141kb,D)

Title: Phase separation of binary condensates in harmonic and lattice

potentials

Authors: S. Gautam and D. Angom

Categories: cond-mat.quant-gas

Comments: 12 pages, 9 figures, typos removed, title changed

\\ ( http://arxiv.org/abs/1008.4732 , 1141kb)

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\\

arXiv:1007.2891

replaced with revised version Fri, 3 Sep 2010 12:09:31 GMT (766kb)

Title: Rotons in a hybrid Bose-Fermi system

Authors: I.A. Shelykh, T. Taylor and A.V. Kavokin

Categories: cond-mat.quant-gas

Comments: Revised version with parameters of realistic GaAs double quantum

well, accepted for publication in Phys. Rev. Lett

\\ ( http://arxiv.org/abs/1007.2891 , 766kb)

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\\

arXiv:1004.0304

replaced with revised version Mon, 6 Sep 2010 08:13:45 GMT (39kb)

Title: Bose-Fermi-Hubbard model at finite temperature

Authors: T S Mysakovych

Categories: cond-mat.other

Journal-ref: J. Phys.: Condens. Matter 22 (2010) 355601

\\ ( http://arxiv.org/abs/1004.0304 , 39kb)

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\\

arXiv:1005.1138

replaced with revised version Mon, 6 Sep 2010 08:50:24 GMT (683kb,D)

Title: Manipulation of coherent atom waves using accelerated two-dimensional

optical lattices

Authors: Wei-Chih Ting, Dian-Jiun Han, and Shin-Tza Wu

Categories: cond-mat.quant-gas

Comments: Figures with low resolution; high quality ones can be supplied on

request

Journal-ref: New J Phys, 12, 083059 (2010)

DOI: 10.1088/1367-2630/12/8/083059

\\ ( http://arxiv.org/abs/1005.1138 , 683kb)

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\\

arXiv:1008.3406 (*cross-listing*)

replaced with revised version Mon, 6 Sep 2010 11:23:07 GMT (700kb,D)

Title: Quantum phase diagram of the integrable p_x+ip_y fermionic superfluid

Authors: Stefan M.A. Rombouts, Jorge Dukelsky, Gerardo Ortiz

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

Comments: 12 figures

\\ ( http://arxiv.org/abs/1008.3406 , 700kb)

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\\

arXiv:1001.1803

replaced with revised version Mon, 6 Sep 2010 19:13:20 GMT (44kb)

Title: Decoherence and damping in ideal gases

Authors: Janos Polonyi

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

Comments: final version, to appear in Europhysical Letter

\\ ( http://arxiv.org/abs/1001.1803 , 44kb)

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\\

arXiv:1006.2241

replaced with revised version Wed, 8 Sep 2010 15:05:26 GMT (151kb,D)

Title: Radio Frequency Association of Efimov Trimers

Authors: Thomas Lompe, Timo B. Ottenstein, Friedhelm Serwane, Andre N. Wenz,

Gerhard Z\"urn and Selim Jochim

Categories: cond-mat.quant-gas

Comments: 15 pages, 6 figures

\\ ( http://arxiv.org/abs/1006.2241 , 151kb)

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\\

arXiv:1004.5400

replaced with revised version Wed, 8 Sep 2010 15:33:09 GMT (123kb)

Title: Klein tunneling and Dirac potentials in trapped ions

Authors: J. Casanova, J. J. Garcia-Ripoll, R. Gerritsma, C. F. Roos, and E.

Solano

Categories: quant-ph cond-mat.mes-hall cond-mat.quant-gas hep-th

Comments: 4 pages, 3 figures, minor changes

Journal-ref: Phys. Rev. A. 82, 020101(R) (2010)

\\ ( http://arxiv.org/abs/1004.5400 , 123kb)

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\\

arXiv:1008.0598

replaced with revised version Wed, 8 Sep 2010 17:14:30 GMT (47kb)

Title: Magnetic phases of spin-3/2 fermions on a spatially anisotropic square

lattice

Authors: A. K. Kolezhuk and T. Vekua

Categories: cond-mat.quant-gas

Comments: 10 Revtex pages, 5 figures; (v2) corrected the last paragraph in

Appendix B and some typos

\\ ( http://arxiv.org/abs/1008.0598 , 47kb)

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\\

arXiv:1007.5380

replaced with revised version Wed, 8 Sep 2010 19:25:16 GMT (754kb)

Title: Phase-space description of the magneto-optical trap

Authors: Rudy Romain (PhLAM), Daniel Hennequin (PhLAM), Philippe Verkerk

(PhLAM)

Categories: physics.atom-ph

\\ ( http://arxiv.org/abs/1007.5380 , 754kb)

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\\

arXiv:0901.4778

replaced with revised version Thu, 9 Sep 2010 16:42:56 GMT (1212kb)

Title: Dynamics of quantum phase transitions in Dicke and Lipkin-Meshkov-Glick

models

Authors: A.P. Itin, P. T\"orm\"a

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

Comments: 21 pages, 33 figures; Comments to ver.3: major revision, added

Lipkin-Meshkov-Glick model and Dicke model with counterrotating terms

\\ ( http://arxiv.org/abs/0901.4778 , 1212kb)

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\\

arXiv:1004.0510

replaced with revised version Thu, 9 Sep 2010 17:35:18 GMT (43kb)

Title: Dynamical mean field solution of the Bose-Hubbard model

Authors: Peter Anders, Emanuel Gull, Lode Pollet, Matthias Troyer, Philipp

Werner

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

Comments: 10 pages, 3 figures. includes supplementary material

Journal-ref: Phys. Rev. Lett. 105, 096402 (2010)

\\ ( http://arxiv.org/abs/1004.0510 , 43kb)

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\\

arXiv:0912.2943 (*cross-listing*)

replaced with revised version Thu, 9 Sep 2010 18:38:29 GMT (1452kb)

Title: Interaction of a propagating guided matter wave with a localized

potential

Authors: Giovanni Luca Gattobigio (LCAR), Antoine Couvert (LCAR), Bertrand

Georgeot (LPT), David Gu\'ery-Odelin (LCAR)

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

Journal-ref: New Journal of Physics 12 (2010) 085013

DOI: 10.1088/1367-2630/12/8/085013

\\ ( http://arxiv.org/abs/0912.2943 , 1452kb)

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\\

arXiv:1005.0992

replaced with revised version Thu, 9 Sep 2010 18:55:15 GMT (58kb)

Title: Time-Dependent Mean Field Theory for Quench Dynamics in correlated

electron systems

Authors: Marco Schir\'o, Michele Fabrizio

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

Comments: 4 pages, 2 figures, published version

Journal-ref: Phys. Rev. Lett. 105, 076401 (2010)

DOI: 10.1103/PhysRevLett.105.076401

\\ ( http://arxiv.org/abs/1005.0992 , 58kb)

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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 Thu Nov 04 2010 - 10:05:09 EST

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