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

Date: Wed, 20 May 2009 16:57:48 +1000

Date: Wed, 20 May 2009 16:57:48 +1000

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

Dear subscribers,

Geoff Lee deserves the credit for preparing this email. There are 28 new

preprints and 9 replacements:

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arXiv:0903.2261

Date: Thu, 12 Mar 2009 20:18:32 GMT (76kb)

Title: Modified Macroscopic Quantum Tunneling of a BEC close to a Feshbach

Resonance

Authors: N.T. Zinner and M. Th{\o}gersen

Categories: cond-mat.other

Comments: 4 pages, 3 figures, Revtex4

\\

We consider the stability and macroscopic decay of an ultracold trapped

Bose-Einstein condensate near a Feshbach resonance. Several types of atomic

species and resonances are investigated. Using a modified Gross-Pitaevskii

equation that includes higher-order terms and a multi-channel model of Feshbach

resonances, we find regions around experimentally measured Feshbach resonances

where macroscopic tunneling of the condensate is either suppressed or enhanced

by higher-order interactions. However, to see the effect in realistic

experiments requires very narrow resonances or very small condensates with

particle number of order $10^2$.

\\ ( http://arxiv.org/abs/0903.2261 , 76kb)

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arXiv:0903.2263

Date: Thu, 12 Mar 2009 20:09:01 GMT (511kb)

Title: Shell-Model Monte Carlo Simulations of BCS-BEC Crossover in Few-Fermion

Systems

Authors: N.T. Zinner, K. M{\o}lmer, C. \"Ozen, D.J. Dean, K. Langanke

Categories: cond-mat.supr-con

Comments: 4 pages, 3 figures, Revtex4

\\

We study a trapped system of fermions with a zero-range two-body interaction

using the Shell-Model Monte Carlo method, providing {\em ab initio} results for

the low particle number limit where mean-field theory is not applicable. We

present results for the $N$-body energies as function of interaction strength,

particle number, and temperature. The subtle question of renormalization in a

finite model space is addressed and the convergence of our method and its

applicability across the BCS-BEC crossover is demonstrated. Comparison to N=2

analytics at zero and finite temperature, and to other calculations in the

literature for $N>2$ show very good agreement.

\\ ( http://arxiv.org/abs/0903.2263 , 511kb)

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arXiv:0903.2346

Date: Fri, 13 Mar 2009 10:22:58 GMT (55kb)

Title: Phase diagram of imbalanced fermions in optical lattices

Authors: Xiaoling Cui and Yupeng Wang

Categories: cond-mat.supr-con

Comments: 5 pages, 4 figures

\\

The zero temperature phase diagrams of imbalanced two species fermions in 3D

optical lattices are investigated to evaluate the validity of the Fermi-Hubbard

model. It is found that depending on the filling factor, s-wave scattering

strength and lattice potential, the system may fall into the normal($N$) phase,

magnetized superfluid($SF_M$) or phase separation of $N$ and $BCS$ state. By

tuning these parameters, the superfluidity could be favorable by enhanced

effective couplings or suppressed by the increased band gap. The phase profiles

for imbalanced fermions in the presence of a harmonic trap are also

investigated under LDA, which show some novel structures to those without the

optical lattice.

\\ ( http://arxiv.org/abs/0903.2346 , 55kb)

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arXiv:0903.2459

Date: Fri, 13 Mar 2009 19:11:12 GMT (91kb)

Title: Transport and Control in One-Dimensional Systems

Authors: L. F. Santos

Categories: cond-mat.stat-mech

Comments: 8 pages, 4 figures. Talk given at the workshop `Integrable Quantum

Systems and Solvable Statistical Mechanics Models', Montreal, July 2008.

Submitted to J. Math. Phys

\\

We study transport of local magnetization in a Heisenberg spin-1/2 chain at

zero temperature. The system is initially prepared in a highly excited pure

state far from equilibrium and its evolution is analyzed via exact

diagonalization. Integrable and non-integrable regimes are obtained by

adjusting the parameters of the Hamiltonian, which allows for the comparison of

transport behaviors in both limits. In the presence of nearest neighbor

interactions only, the transport behavior in the integrable clean system

contrasts with the chaotic chain with on-site defects, oscillations in the

first suggesting ballistic transport and a fast decay in the latter indicating

diffusive transport. The results for a non-integrable system with frustration

are less conclusive, similarities with the integrable chain being verified. We

also show how methods of quantum control may be applied to chaotic systems to

induce a desired transport behavior, such as that of an integrable system.

\\ ( http://arxiv.org/abs/0903.2459 , 91kb)

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arXiv:0903.2401

Date: Fri, 13 Mar 2009 13:05:54 GMT (3080kb)

Title: Unpublished opening lecture for the course on the theory of relativity

in Argentina, 1925

Authors: Albert Einstein, Alejandro Gangui and Eduardo L. Ortiz

Categories: physics.hist-ph physics.soc-ph

Comments: Companion paper to arXiv:0903.2064 . Published version available at

http://www.universoeinstein.com.ar/einsteinargentina.htm. Translated by

Alejandro Gangui and Eduardo L. Ortiz

Journal-ref: Science in Context, Vol. 21, issue 3, pp. 451-459 (2008)

\\

Honorable Rector, Honorable Professors, and Students of this University: In

these times of political and economic struggle and nationalistic fragmentation,

it is a particular joy for me to see people assembling here to give their

attention exclusively to the highest values that are common to us all. I am

glad to be in this blessed land before a small circle of people who are

interested in topics of science to speak on those issues that, in essence, are

the subject of my own meditations.. [abridged].

\\ ( http://arxiv.org/abs/0903.2401 , 3080kb)

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arXiv:0903.2519

Date: Sat, 14 Mar 2009 01:02:26 GMT (146kb)

Title: High Precision Quantum Monte Carlo Study of the 2D Fermion Hubbard Model

Authors: C. N. Varney, C.-R. Lee, Z. J. Bai, S. Chiesa, M. Jarrell, and R. T.

Scalettar

Categories: cond-mat.str-el

Comments: 7 pages, 11 figures. Submitted to Phys. Rev. A

\\

We report large scale determinant Quantum Monte Carlo calculations of the

effective bandwidth, momentum-space Green's function, and magnetic correlations

of the square lattice fermion Hubbard Hamiltonian at half-filling. The sharp

Fermi surface of the non-interacting limit is significantly broadened by the

electronic correlations, but retains signatures of the approach to the edges of

the first Brillouin zone as the density increases. Finite size scaling of

simulations on large lattices allows us to extract the interaction dependence

of the antiferromagnetic order parameter, exhibiting its evolution from weak

coupling to the strong coupling Heisenberg limit. Our lattices provide improved

resolution of the Green's function in momentum space, allowing a more

quantitative comparison with time of flight optical lattice experiments.

\\ ( http://arxiv.org/abs/0903.2519 , 146kb)

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arXiv:0903.2534

Date: Sat, 14 Mar 2009 08:47:16 GMT (555kb)

Title: Vortex-Induced Phase Slip Dissipation in a Toroidal Bose-Einstein

Condensate Flowing Trough a Barrier

Authors: F. Piazza, L. A. Collins, and A. Smerzi

Categories: cond-mat.other

\\

We study superfluid dissipation due to phase slips for a BEC flowing through

a repulsive barrier inside a torus. The barrier is adiabatically raised across

the annulus while the condensate flows with a finite quantized angular

momentum. We find that, at a critical height, a vortex moves radially from the

inner region and reaches the barrier to eventually circulate around the

annulus. At a slightly higher barrier, an anti-vortex also enters into the

torus from the outward region. The vortex and anti-vortex decrease the total

angular momentum by leaving behind their respective paths a $2 \pi$ phase slip.

When they collide or orbit along the same loop, the condensate suffers a global

$2\pi$ phase slip, and the total angular momentum decreases by one quantum. The

analysis is based on numerical simulations of the Gross-Pitaevskii equation

both in two- and three-dimensions.

\\ ( http://arxiv.org/abs/0903.2534 , 555kb)

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arXiv:0903.2537

Date: Sat, 14 Mar 2009 09:48:14 GMT (79kb)

Title: Quantum Monte Carlo simulations for the Bose-Hubbard model with random

chemical potential; localized Bose-Einstein condensation without

superfluidity

Authors: Mitsuaki Tsukamoto, Makoto Tsubota

Categories: cond-mat.stat-mech

Comments: 4 pages, 7 figures

\\

The hardcore-Bose-Hubbard model with random chemical potential is

investigated using quantum Monte Carlo simulation. We consider two cases of

random distribution of the chemical potential: a uniformly random distribution

and a correlated distribution. The temperature dependences of the superfluid

density, the specific heat, and the correlation functions are calculated. If

the distribution of the randomness is correlated, there exists an intermediate

state, which can be thought of as a localized condensate state of bosons,

between the superfluid state and the normal state.

\\ ( http://arxiv.org/abs/0903.2537 , 79kb)

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arXiv:0903.2552

Date: Sat, 14 Mar 2009 16:01:36 GMT (405kb)

Title: Quantum fluctuations of a Bose-Josephson junction in a

quasi-one-dimensional ring trap

Authors: N. Didier, A. Minguzzi, F.W.J. Hekking

Categories: cond-mat.mes-hall

Comments: 9 pages, 8 figures

\\

Using a Luttinger-liquid approach we study the quantum fluctuations of a

Bose-Josephson junction, consisting of a Bose gas confined to a quasi

one-dimensional ring trap which contains a localized repulsive potential

barrier. For an infinite barrier we study the one-particle and two-particle

static correlation functions. For the one-body density-matrix we obtain

different power-law decays depending on the location of the probe points with

respect to the position of the barrier. This quasi-long range order can be

experimentally probed in principle using an interference measurement. The

corresponding momentum distribution at small momenta is also shown to be

affected by the presence of the barrier and to display the universal power-law

behavior expected for an interacting 1D fluid. We also evaluate the particle

density profile, and by comparing with the exact results in the Tonks-Girardeau

limit we fix the nonuniversal parameters of the Luttinger-liquid theory. Once

the parameters are determined from one-body properties, we evaluate the

density-density correlation function, finding a remarkable agreement between

the Luttinger liquid predictions and the exact result in the Tonks-Girardeau

limit, even at the length scale of the Friedel-like oscillations which

characterize the behavior of the density-density correlation function at

intermediate distance. Finally, for a large but finite barrier we use the

one-body correlation function to estimate the effect of quantum fluctuations on

the renormalization of the barrier height, finding a reduction of the effective

Josephson coupling energy, which depends on the length of the ring and on the

interaction strength.

\\ ( http://arxiv.org/abs/0903.2552 , 405kb)

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arXiv:0903.2568

Date: Sat, 14 Mar 2009 18:44:35 GMT (1756kb)

Title: Collisional cooling of ultra-cold atom ensembles using Feshbach

resonances

Authors: L. Mathey, Eite Tiesinga, Paul S. Julienne, Charles W. Clark

Categories: cond-mat.other

Comments: 4 pages, 3 figures

\\

We propose a new type of cooling mechanism for ultra-cold fermionic atom

ensembles, which capitalizes on the energy dependence of inelastic collisions

in the presence of a Feshbach resonance. We first discuss the case of a single

magnetic resonance, and find that the final temperature and the cooling rate is

limited by the width of the resonance. A concrete example, based on a p-wave

resonance of $^{40}$K, is given. We then improve upon this setup by using both

a very sharp optical or radio-frequency induced resonance and a very broad

magnetic resonance and show that one can improve upon temperatures reached with

current technologies.

\\ ( http://arxiv.org/abs/0903.2568 , 1756kb)

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arXiv:0903.2707

Date: Mon, 16 Mar 2009 09:10:02 GMT (830kb)

Title: Non-Hermitian Generalization of the Bethe-Ansatz Excited States and

Dielectric Breakdown in the Hubbard Model out of Equilibrium

Authors: Takashi Oka and Hideo Aoki

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

Comments: 5 pages, 3 figures

\\

Many-body models exactly solvable in nonequilibrium situations will serve to

deepen the understanding of nonequilibrium physics. Here we explore this by

applying the Dykhne-Davis-Pechukas approach to the dielectric breakdown of Mott

insulators in strong electric fields, which relates, via an analytic

continuation, the quantum tunneling rate with the Bethe-ansatz solution for

excited states in the Hubbard model extended to a non-Hermitian case. This has

enabled us to (i) reveal that two apparently unrelated theories, one with a

many-body Landau-Zener tunneling and the other a non-Hermitian approach, are in

fact intimately related, and (ii) give a picture for the breakdown in the

thermodynamic limit.

\\ ( http://arxiv.org/abs/0903.2707 , 830kb)

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arXiv:0903.2723

Date: Mon, 16 Mar 2009 11:03:25 GMT (376kb)

Title: Exciton-polariton condensation in a natural two dimensional trap

Authors: D. Sanvitto, A. Amo, L. Vina, R. Andre, D. Solnyshkov and G. Malpuech

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

Comments: 10 pages, 3 figures

\\

Bose Einstein condensation of exciton-polaritons has recently been reported

in homogeneous structures only affected by random in-plane fluctuations. We

have taken advantage of the ubiquitous defects in semiconductor microcavities

to reveal the spontaneous dynamical condensation of polaritons in the quantised

levels of a trap. We observe condensation in several quantized states, taking

their snapshots in real and reciprocal space. We show also the effect of

particle interactions for high occupations numbers, revealed by a change in the

confined wave function toward the Thomas Fermi profile.

\\ ( http://arxiv.org/abs/0903.2723 , 376kb)

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arXiv:0903.2796

Date: Mon, 16 Mar 2009 16:29:02 GMT (63kb)

Title: Cooling atoms into entangled states

Authors: Giovanni Vacanti and Almut Beige

Categories: quant-ph

Comments: 16 pages, 6 figures

\\

We discuss the possibility to prepare highly entangled state by simply

cooling atoms into the ground state of an applied interaction Hamiltonian.

Different from previous proposals for state preparation via cooling [B. Kraus

et al., Phys. Rev. A 78, 042397 (2008) and F. Verstraete et al.,

arXiv:0804.1888], we do not require the existence of an exact dark state which

is the only stationary state of the system. Instead, our scheme is analog to

laser sideband cooling. Laser fields are applied such that the target state is

highly detuned, while all other qubit states are in resonance. After presenting

the general theory, we discuss concrete applications with one and two qubits.

\\ ( http://arxiv.org/abs/0903.2796 , 63kb)

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arXiv:0903.2261 (*cross-listing*)

Date: Thu, 12 Mar 2009 20:18:32 GMT (76kb)

Title: Modified Macroscopic Quantum Tunneling of a BEC close to a Feshbach

Resonance

Authors: N.T. Zinner and M. Th{\o}gersen

Categories: cond-mat.other quant-ph

Comments: 4 pages, 3 figures, Revtex4

\\

We consider the stability and macroscopic decay of an ultracold trapped

Bose-Einstein condensate near a Feshbach resonance. Several types of atomic

species and resonances are investigated. Using a modified Gross-Pitaevskii

equation that includes higher-order terms and a multi-channel model of Feshbach

resonances, we find regions around experimentally measured Feshbach resonances

where macroscopic tunneling of the condensate is either suppressed or enhanced

by higher-order interactions. However, to see the effect in realistic

experiments requires very narrow resonances or very small condensates with

particle number of order $10^2$.

\\ ( http://arxiv.org/abs/0903.2261 , 76kb)

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arXiv:0903.2745

Date: Mon, 16 Mar 2009 12:55:39 GMT (135kb)

Title: All-optical runaway evaporation to Bose-Einstein condensation

Authors: Jean-Francois Cl\'ement (LCFIO), Jean-Philippe Brantut (LCFIO), Martin

Robert De Saint Vincent (LCFIO), Robert A. Nyman (LCFIO), A. Aspect (LCFIO),

Thomas Bourdel (LCFIO), Philippe Bouyer (LCFIO)

Categories: physics.atom-ph

\\

We demonstrate runaway evaporative cooling directly with a tightly confining

optical dipole trap and achieve fast production of condensates of 1.5x10^5 87Rb

atoms. Our scheme is characterized by an independent control of the optical

trap confinement and depth, permitting forced evaporative cooling without

reducing the trap stiffness. Although our configuration is particularly well

suited to the case of 87Rb atoms in a 1565nm optical trap, where an efficient

initial loading is possible, our scheme is general and should allow all-optical

evaporative cooling at constant stiffness for most species.

\\ ( http://arxiv.org/abs/0903.2745 , 135kb)

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arXiv:0903.2991

Date: Tue, 17 Mar 2009 15:54:18 GMT (3015kb)

Title: Density, phase and coherence properties of a low dimensional

Bose-Einstein systems moving in a disordered potential

Authors: Chaitanya Joshi, Sankalpa Ghosh (Physics Department, I. I. T. Delhi)

Categories: cond-mat.mes-hall cond-mat.dis-nn

Comments: 12 pages, 15 figures, EPJB style, accepted for publication in the

topical issue of EPJB on "Novel Quantum phases and Mesoscopic physics in

Quantum gases"

\\

We present a detailed numerical study of the dynamics of a disordered

one-dimensional Bose-Einstein condensates in position and momentum space. We

particularly focus on the region where non-linearity and disorder

simultaneously effect the time propagation of the condensate as well as the

possible interference between various parts of the matter wave. We report

oscillation between spatially extended and localized behavior for the

propagating condensate which dies down with increasing non-linearity. We also

report intriguing behavior of the phase fluctuation and the coherence

properties of the matter wave. We also briefly compare these behavior with that

of a two-dimensional condensate. We mention the relevance of our results to the

related experiments on Anderson localization and indicate the possibility of

future experiments

\\ ( http://arxiv.org/abs/0903.2991 , 3015kb)

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arXiv:0903.3006

Date: Tue, 17 Mar 2009 17:07:01 GMT (22kb)

Title: Theory of Radio Frequency Spectroscopy of Polarized Fermi Gases

Authors: William Schneider, Vijay B. Shenoy, Mohit Randeria

Categories: cond-mat.other

Comments: 4 page, 3 figures

\\

We present two exact results for singular features in the radio frequency

intensity $I(\omega)$ for ultracold Fermi gases. First, in the absence of final

state interactions, $I(\omega)$ has a universal high frequency tail $

C\omega^{-3/2}$ for \emph{all} many-body states, where $C$ is Tan's contact.

Second, in a \emph{normal} Fermi liquid at T=0, $I(\omega)$ has a jump

discontinuity of $Z/(1 - m/m^{*})$, where $Z$ is the quasiparticle weight and

$m^*/m$ the mass renormalization. We then describe various approximations for

$I(\omega)$ in polarized normal gases. We show why an approximation that is

exact in the $n_\dn=0$ limit, fails qualitatively for $n_{\dn} > 0$: there is

no universal tail and sum rules are violated. The simple ladder approximation

is qualitatively correct for very small $n_{\dn}$, but not quantitatively.

\\ ( http://arxiv.org/abs/0903.3006 , 22kb)

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arXiv:0903.3030

Date: Tue, 17 Mar 2009 19:35:34 GMT (19kb)

Title: Critical Behaviour in Trapped Strongly Interacting Fermi Gases

Authors: E. Taylor

Categories: cond-mat.stat-mech

Comments: 6 pages, 2 figures

\\

We investigate the width of the Ginzburg critical region and experimental

signatures of critical behaviour in strongly interacting trapped Fermi gases

close to unitarity, where the s-wave scattering length diverges. Despite the

fact that the width of the critical region is of the order unity, evidence of

critical behaviour in the thermodynamics of trapped gases is strongly

suppressed by their inhomogeneity. The specific heat of a harmonically confined

gas, for instance, is linear in the reduced temperature $\varepsilon = 1-T/T_c$

close to $T_c$. Using higher-order power-law potentials to confine the gas,

critical behaviour becomes more apparent and a lambda curve should be visible

in the specific heat.

\\ ( http://arxiv.org/abs/0903.3030 , 19kb)

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arXiv:0903.2953

Date: Tue, 17 Mar 2009 12:14:21 GMT (946kb)

Title: Tapered optical fibers as tools for probing magneto-optical trap

characteristics

Authors: M.J. Morrissey, K. Deasy, Y. Wu, S. Chakrabarti and S. Nic Chormaic

Categories: quant-ph

Comments: 21 pages, 5 figures

\\

We present a novel technique for measuring the characteristics of a

magneto-optical trap for cold atoms by monitoring the spontaneous emission from

trapped atoms coupled into the guided mode of a tapered optical nanofiber. We

show that the nanofiber is highly sensitive to very small numbers of atoms

close to its surface. The size and shape of the MOT, determined by translating

the cold atom cloud across the tapered fiber, is in excellent agreement with

measurements obtained using the conventional method of fluorescence imaging

using a CCD camera. The coupling of atomic fluorescence into the tapered fiber

also allows us to monitor the loading and lifetime of the trap. The results are

compared to those achieved by focusing the MOT fluorescence onto a photodiode

and it was seen that the tapered fiber gives slightly longer loading and

lifetime measurements due to the sensitivity of the fiber, even when very few

atoms are present.

\\ ( http://arxiv.org/abs/0903.2953 , 946kb)

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arXiv:0903.2942

Date: Tue, 17 Mar 2009 11:07:21 GMT (850kb)

Title: Influence of a Feshbach resonance on the photoassociation of LiCs

Authors: J. Deiglmayr, P. Pellegrini, A. Grochola, M. Repp, R. C\^ot\'e, O.

Dulieu, R. Wester and M. Weidem\"uller

Categories: physics.atom-ph

Comments: Submitted to New Journal of Physics, Special Issue on Cold and

Ultracold molecules. 16 pages, 8 figures

\\

We analyse the formation of ultracold 7Li133Cs molecules in the rovibrational

ground state through photoassociation into the B1Pi state, which has recently

been reported [J. Deiglmayr et al., Phys. Rev. Lett. 101, 133004 (2008)].

Absolute rate constants for photoassociation at large detunings from the atomic

asymptote are determined and are found to be surprisingly large. The

photoassociation process is modeled using a full coupled-channel calculation

for the continuum state, taking all relevant hyperfine states into account. The

enhancement of the photoassociation rate is found to be caused by an `echo' of

the triplet component in the singlet component of the scattering wave function

at the inner turning point of the lowest triplet a3Sigma+ potential. This

perturbation can be ascribed to the existence of a broad Feshbach resonance at

low scattering energies. Our results elucidate the important role of couplings

in the scattering wave function for the formation of deeply bound ground state

molecules via photoassociation.

\\ ( http://arxiv.org/abs/0903.2942 , 850kb)

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arXiv:0903.3185

Date: Wed, 18 Mar 2009 15:32:34 GMT (1552kb)

Title: Ab-initio determination of Bose-Hubbard parameters for two ultracold

atoms in an optical lattice

Authors: Philipp Schneider, Sergey Grishkevich, and Alejandro Saenz

Categories: quant-ph

Comments: 13 pages, 11 figures

\\

We calculate numerically the exact energy spectrum of the six dimensional

problem of two interacting Bosons in a three-well optical lattice. The

particles interact via a full Born-Oppenheimer potential which can be adapted

to model the behavior of the s-wave scattering length at Feshbach resonances.

By adjusting the parameters of the corresponding Bose-Hubbard (BH) Hamiltonian

the deviation between the numerical energy spectrum and the BH spectrum is

minimized. This defines the optimal BH parameter set which we compare to the

standard parameters of the BH model. The range of validity of the BH model with

these parameter sets is examined, and an improved analytical prediction of the

interaction parameter is introduced. Furthermore, the extended BH model and

implications due to the energy dependence of the scattering length and

couplings to higher Bloch bands at a Feshbach resonance are discussed.

\\ ( http://arxiv.org/abs/0903.3185 , 1552kb)

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arXiv:0903.3147

Date: Wed, 18 Mar 2009 12:12:25 GMT (100kb)

Title: Autoionization of an ultracold Rydberg gas through resonant dipole

coupling

Authors: T. Amthor, J. Denskat, C. Giese, N. N. Bezuglov, A. Ekers, L.

Cederbaum, M. Weidem\"uller

Categories: physics.atom-ph

\\

We investigate a possible mechanism for the autoionization of ultracold

Rydberg gases, based on the resonant coupling of Rydberg pair states to the

ionization continuum. Unlike an atomic collision where the wave functions begin

to overlap, the mechanism considered here involves only the long-range dipole

interaction and is in principle possible in a static system. It is related to

the process of intermolecular Coulombic decay (ICD). In addition, we include

the interaction-induced motion of the atoms and the effect of multi-particle

systems in this work. We find that the probability for this ionization

mechanism can be increased in many-particle systems featuring attractive or

repulsive van der Waals interactions. However, the rates for ionization through

resonant dipole coupling are very low. It is thus unlikely that this process

contributes to the autoionization of Rydberg gases in the form presented here,

but it may still act as a trigger for secondary ionization processes. As our

picture involves only binary interactions, it remains to be investigated if

collective effects of an ensemble of atoms can significantly influence the

ionization probability. Nevertheless our calculations may serve as a starting

point for the investigation of more complex systems, such as the coupling of

many pair states proposed in [Tanner et al., PRL 100, 043002 (2008)].

\\ ( http://arxiv.org/abs/0903.3147 , 100kb)

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arXiv:0903.3202

Date: Wed, 18 Mar 2009 16:59:35 GMT (100kb)

Title: Collisions of bosonic ultracold polar molecules in microwave traps

Authors: Alexander V. Avdeenkov

Categories: physics.atom-ph

Comments: accepted for publication in New J. Phys. (special issue on ultracold

molecules)

\\

The collisions between linear polar molecules, trapped in a microwave field

with circular polarization, are theoretically analyzed. The microwave trap

suggested by DeMille \cite{DeMille} seems to be rather advantageous in

comparison with other traps. Here we have demonstrated that the microwave trap

can provide a successful evaporative cooling for polar molecules in a rather

broad range of frequencies of the AC-field. We suggested that not only ground

state polar molecules but also molecules in some other states can be safely

trapped.

But the state in which molecules can be safely loaded and trapped depends on

the frequency of the AC-field.

\\ ( http://arxiv.org/abs/0903.3202 , 100kb)

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arXiv:0903.3194

Date: Wed, 18 Mar 2009 16:09:09 GMT (172kb)

Title: 60 years of Broken Symmetries in Quantum Physics (From the Bogoliubov

Theory of Superfluidity to the Standard Model)

Authors: D. V. Shirkov

Categories: physics.hist-ph cond-mat.supr-con hep-ph hep-th

Comments: 18 pages, 4 figures, to appear in Physics -- Uspekhi

\\

A retrospective historical overview of the phenomenon of spontaneous symmetry

breaking (SSB) in quantum theory, the issue that has been implemented in

particle physics in the form of the Higgs mechanism. The main items are:

-- The Bogoliubov's microscopical theory of superfluidity (1946);

-- The BCS-Bogoliubov theory of superconductivity (1957);

-- Superconductivity as a superfluidity of Cooper pairs (Bogoliubov - 1958);

-- Transfer of the SSB into the QFT models (early 60s);

-- The Higgs model triumph in the electro-weak theory (early 80s).

The role of the Higgs mechanism and its status in the current Standard Model

is also touched upon.

\\ ( http://arxiv.org/abs/0903.3194 , 172kb)

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arXiv:0903.3282

Date: Thu, 19 Mar 2009 08:39:09 GMT (374kb)

Title: Direct observation of number squeezing in an optical lattice

Authors: A. Itah, H. Veksler, O. Lahav, A. Blumkin, C. Moreno, C. Gordon and J.

Steinhauer

Categories: cond-mat.other

\\

We present an in-situ study of an optical lattice with tunneling and single

lattice site resolution. This system provides an important step for realizing a

quantum computer. The real-space images show the fluctuations of the atom

number in each site. The sub-Poissonian distribution results from the approach

to the Mott insulator state, combined with the dynamics of density-dependent

losses, which result from the high densities of optical lattice experiments.

These losses are clear from the shape of the lattice profile. Furthermore, we

find that the lattice is not in the ground state despite the momentum

distribution which shows the reciprocal lattice. These effects may well be

relevant for other optical lattice experiments, past and future. The lattice

beams are derived from a microlens array, resulting in lattice beams which are

perfectly stable relative to one another.

\\ ( http://arxiv.org/abs/0903.3282 , 374kb)

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arXiv:0903.3284

Date: Thu, 19 Mar 2009 08:23:33 GMT (1232kb)

Title: Light-pulse atom interferometry in microgravity

Authors: Guillaume Stern (LCFIO, SYRTE), Baptiste Battelier (LCFIO), R\'emi

Geiger (LCFIO), Gael Varoquaux (LCFIO), Andr\'e Villing (LCFIO), Fr\'ed\'eric

Moron (LCFIO), Olivier Carra (ONERA), Nassim Zahzam (ONERA), Yannick Bidel

(ONERA), Oualid Chaibi (SYRTE), Frank Pereira Dos Santos (SYRTE), Alexandre

Bresson (ONERA), Arnaud Landragin (SYRTE), Philippe Bouyer (LCFIO)

Categories: cond-mat.other

\\

We describe the operation of a light pulse interferometer using cold 87Rb

atoms in reduced gravity. Using a series of two Raman transitions induced by

light pulses, we have obtained Ramsey fringes in the low gravity environment

achieved during parabolic flights. With our compact apparatus, we have operated

in a regime which is not accessible on ground. In the much lower gravity

environment and lower vibration level of a satellite, our cold atom

interferometer could measure accelerations with a sensitivity orders of

magnitude better than the best ground based accelerometers and close to proven

spaced-based ones.

\\ ( http://arxiv.org/abs/0903.3284 , 1232kb)

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\\

arXiv:0903.3345

Date: Thu, 19 Mar 2009 15:11:13 GMT (45kb)

Title: Time-resolved measurement of Landau-Zener tunneling in periodic

potentials

Authors: A. Zenesini and H. Lignier and G. Tayebirad and J. Radogostowicz and

D. Ciampini and R. Mannella and S. Wimberger and O. Morsch and E. Arimondo

Categories: cond-mat.other

Comments: 5 pages, 3 figures

\\

We report time-resolved measurements of Landau-Zener tunneling of

Bose-Einstein condensates in accelerated optical lattices, clearly resolving

the step-like time dependence of the band populations. Using different

experimental protocols we were able to measure the tunneling probability both

in the adiabatic and in the diabatic bases of the system. We also

experimentally determine the contribution of the momentum width of the Bose

condensates to the width of the tunneling steps and discuss the implications

for measuring the jump time in the Landau-Zener problem.

\\ ( http://arxiv.org/abs/0903.3345 , 45kb)

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\\

arXiv:0903.3348

Date: Thu, 19 Mar 2009 15:24:04 GMT (1633kb)

Title: Universal Four-Boson States in Ultracold Molecular Gases: Resonant

Effects in Dimer-Dimer Collisions

Authors: J. P. D'Incao, J. von Stecher, and Chris H. Greene

Categories: physics.atom-ph

Comments: 4.1 pages, 3 figures

\\

We study the manifestations of universal four-body physics in ultracold

dimer-dimer collisions.

We show that resonant features associated with three-body Efimov physics and

dimer-dimer scattering lengths are universally related. The emergence of

universal four-boson states allows for the tunability of the dimer-dimer

interaction, thus enabling the future study of ultracold molecular gases with

both attractive and repulsive interactions. Moreover, our study of the

interconversion between dimers and Efimov trimers shows that $B_{2}+B_{2}\to

B_{3}+B$ rearrangement reactions can provide an efficient trimer formation

mechanism. Our analysis of the temperature dependence of this reaction provides

an interpretation of the available experimental data and sheds light on the

possible experimental realization of rearrangement processes in ultracold

gases.

\\ ( http://arxiv.org/abs/0903.3348 , 1633kb)

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The replacements:

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\\

arXiv:cond-mat/0610116

replaced with revised version Fri, 13 Mar 2009 14:43:48 GMT (18kb)

Title: Resonant Dimer Relaxation in Cold Atoms with a Large Scattering Length

Authors: Eric Braaten (Ohio State U.), H.-W. Hammer (Bonn U.)

Categories: cond-mat.other nucl-th

Comments: 4 pages, 2 eps figures, normalization error in figures corrected,

equations unchanged

Report-no: HISKP-TH-06-26

Journal-ref: Phys.Rev.A75:052710,2007

DOI: 10.1103/PhysRevA.75.052710

\\ ( http://arxiv.org/abs/cond-mat/0610116 , 18kb)

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\\

arXiv:0903.2242

replaced with revised version Fri, 13 Mar 2009 11:41:19 GMT (552kb,D)

Title: Quantum Noise Interference and Back-action Cooling in Cavity

Nanomechanics

Authors: Florian Elste, S. M. Girvin, A. A. Clerk

Categories: cond-mat.mes-hall

Comments: 4+ pages, 2 figures. Error in second last paragraph corrected

\\ ( http://arxiv.org/abs/0903.2242 , 552kb)

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\\

arXiv:0711.1772

replaced with revised version Mon, 16 Mar 2009 10:49:40 GMT (337kb)

Title: Bloch oscillations of atoms in an optical multiphoton potential

Authors: Tobias Salger, Gunnar Ritt, Carsten Geckeler, Sebastian Kling, Martin

Weitz

Categories: cond-mat.other

Comments: 5 figures

Journal-ref: Phys. Rev. A 79, 011605(R) (2009)

DOI: 10.1103/PhysRevA.79.011605

\\ ( http://arxiv.org/abs/0711.1772 , 337kb)

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\\

arXiv:0811.3623

replaced with revised version Mon, 16 Mar 2009 15:04:08 GMT (201kb)

Title: Superfluid-density of the ultra-cold Fermi gas in optical lattices

Authors: T. Paananen

Categories: cond-mat.other

Comments: 20 pages, 7 figures

\\ ( http://arxiv.org/abs/0811.3623 , 201kb)

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\\

arXiv:0806.1211

replaced with revised version Tue, 17 Mar 2009 11:20:36 GMT (508kb)

Title: Universal dephasing in a chiral 1D interacting fermion system

Authors: Clemens Neuenhahn, Florian Marquardt

Categories: cond-mat.mes-hall

Comments: 5 pages, 3 figures; minor changes, version as published;

Journal-ref: Physical Review Letters 102, 046806 (2009)

DOI: 10.1103/PhysRevLett.102.046806

\\ ( http://arxiv.org/abs/0806.1211 , 508kb)

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\\

arXiv:0903.1647

replaced with revised version Mon, 16 Mar 2009 22:19:03 GMT (21kb)

Title: Stability of low-dimensional multicomponent Bose gases

Authors: Alexei Kolezhuk

Categories: cond-mat.other cond-mat.str-el

Comments: 4 pages, 2 figures; (v2) shortened, references corrected

\\ ( http://arxiv.org/abs/0903.1647 , 21kb)

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\\

arXiv:0712.0880

replaced with revised version Wed, 18 Mar 2009 06:59:58 GMT (100kb)

Title: Loss of Superfluidity in Bose-Einstein Condensate in an Optical lattice

with Two- and Three-Body Interactions

Authors: Priyam Das, Manan Vyas and Prasanta K. Panigrahi

Categories: cond-mat.other

Comments: 4 pages, 1 figure

\\ ( http://arxiv.org/abs/0712.0880 , 100kb)

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\\

arXiv:0810.3088

replaced with revised version Wed, 18 Mar 2009 11:45:40 GMT (150kb)

Title: Spacetime analogue of Bose-Einstein condensates: Bogoliubov-de Gennes

formulation

Authors: Yasunari Kurita, Michikazu Kobayashi, Takao Morinari, Makoto Tsubota,

Hideki Ishihara

Categories: cond-mat.other gr-qc

Comments: 8 pages, 6 figures

Report-no: OCU-PHYS-305, AP-GR-62, YITP-08-77

\\ ( http://arxiv.org/abs/0810.3088 , 150kb)

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\\

arXiv:0811.2436

replaced with revised version Thu, 19 Mar 2009 11:16:03 GMT (249kb)

Title: Stationary waves in a supersonic flow of a two-component Bose gas

Authors: L.Yu. Kravchenko, D.V. Fil

Categories: cond-mat.other

Comments: 12 pages, 8 figures

\\ ( http://arxiv.org/abs/0811.2436 , 249kb)

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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 =========================================================================Received on Thu May 21 2009 - 15:50:53 EST

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