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

Date: Tue, 24 Aug 2010 22:53:55 +1000

Date: Tue, 24 Aug 2010 22:53:55 +1000

Dear subscribers,

This week's selection was compiled by Mike Garrett, and contains 35 new

abstracts and 12 replacements.

------------------------------------------------------------------------------

\\

arXiv:0910.1749 (*cross-listing*)

Date: Fri, 9 Oct 2009 14:41:16 GMT (186kb)

Date (revised v2): Tue, 1 Dec 2009 14:25:44 GMT (186kb)

Date (revised v3): Fri, 14 May 2010 13:48:33 GMT (187kb)

Title: Fermionization dynamics of a strongly interacting 1D Bose gas after an

interaction quench

Authors: Dominik Muth, Bernd Schmidt, and Michael Fleischhauer

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

Comments: 10 pages, 4 figures

\\

We study the dynamics of a one-dimensional Bose gas after a sudden change of

the interaction strength from zero to a finite value using the numerical

time-evolving block decimation (TEBD) algorithm. It is shown that despite the

integrability of the system, local quantities such as the two-particle

correlation g^(2)(x, x) attain steady state values in a short characteristic

time inversely proportional to the Tonks parameter gamma and the square of the

density. The asymptotic values are very close to those of a finite temperature

grand canonical ensemble with a local temperature corresponding to initial

energy and density. Non-local density-density correlations on the other hand

approach a steady state on a much larger time scale determined by the finite

propagation velocity of oscillatory correlation waves.

\\ ( http://arxiv.org/abs/0910.1749 , 187kb)

------------------------------------------------------------------------------

\\

arXiv:1004.2408 (*cross-listing*)

Date: Wed, 14 Apr 2010 14:34:38 GMT (149kb)

Date (revised v2): Fri, 16 Apr 2010 00:45:25 GMT (177kb)

Date (revised v3): Wed, 30 Jun 2010 15:05:36 GMT (178kb)

Title: Preparation of stable excited states in an optical lattice via sudden

quantum quench

Authors: Li Wang, Yajiang Hao, and Shu Chen

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

Comments: 5 pages, 4 figures

Journal-ref: Phys. Rev. A 81, 063637 (2010)

DOI: 10.1103/PhysRevA.81.063637

\\

We study how stable excited many-body states of the Bose-Hubbard model,

including both the gas-like state for strongly attractive bosons and bound

cluster state for repulsive bosons, can be produced with cold bosonic atoms in

an one-dimensional optical lattice. Starting from the initial ground states of

strongly interacting bosonic systems, we can achieve stable excited states of

the systems with opposite interaction strength by suddenly switching the

interaction to the opposite limit. By exactly solving dynamics of the

Bose-Hubbard model, we demonstrate that the produced excited state can be a

very stable dynamic state. This allows the experimental study of excited state

properties of ultracold atoms system in optical lattices.

\\ ( http://arxiv.org/abs/1004.2408 , 178kb)

------------------------------------------------------------------------------

\\

arXiv:1004.4099 (*cross-listing*)

Date: Fri, 23 Apr 2010 11:19:48 GMT (198kb)

Title: Discretized vs. continuous models of p-wave interacting fermions in 1D

Authors: Dominik Muth, Michael Fleischhauer, and Bernd Schmidt

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

Comments: 7 pages, 5 figures

\\

We present a general mapping between continuous and lattice models of Bose-

and Fermi-gases in one dimension, interacting via local two-body interactions.

For s-wave interacting bosons we arrive at the Bose-Hubbard model in the weakly

interacting, low density regime. The dual problem of p-wave interacting

fermions is mapped to the spin-1/2 XXZ model close to the critical point in the

highly polarized regime. The mappings are shown to be optimal in the sense that

they produce the least error possible for a given discretization length. As an

application we examine the ground state of a interacting Fermi gas in a

harmonic trap, calculating numerically real-space and momentum-space

distributions as well as two-particle correlations. In the analytically known

limits the convergence of the results of the lattice model to the continuous

one is shown.

\\ ( http://arxiv.org/abs/1004.4099 , 198kb)

------------------------------------------------------------------------------

\\

arXiv:1005.1584 (*cross-listing*)

Date: Mon, 10 May 2010 15:22:32 GMT (15kb)

Date (revised v2): Fri, 25 Jun 2010 10:35:56 GMT (16kb)

Title: Diamagnetism of quantum gases with singular potentials

Authors: Philippe Briet (CPT), Horia D. Cornean (MATH. DEPT., AALBORG

UNIVERSITY), Baptiste Savoie (CPT)

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

\\

We consider a gas of quasi-free quantum particles confined to a finite box,

subjected to singular magnetic and electric fields. We prove in great

generality that the finite volume grand-canonical pressure is jointly analytic

in the chemical potential ant the intensity of the external magnetic field. We

also discuss the thermodynamic limit.

\\ ( http://arxiv.org/abs/1005.1584 , 16kb)

------------------------------------------------------------------------------

\\

arXiv:1006.4755 (*cross-listing*)

Date: Thu, 24 Jun 2010 11:29:37 GMT (750kb)

Title: Hydrodynamic nucleation of vortices and solitons in a resonantly excited

polariton superfluid

Authors: Simon Pigeon (MPQ), Iacopo Carusotto (CRS BEC-INFM), Cristiano Ciuti

(MPQ)

Categories: cond-mat.other physics.optics

Comments:

\\

We present a theoretical study of the hydrodynamic properties of a quantum

gas of exciton-polaritons in a semiconductor microcavity under a resonant laser

excitation. The effect of a spatially extended defect on the superfluid flow is

investigated as a function of the flow speed. The processes that are

responsible for the nucleation of vortices and solitons in the wake of the

defect are characterized, as well as the regimes where the superfluid flow

remains unperturbed. Specific features due to the non-equilibrium nature of the

polariton fluid are put in evidence.

\\ ( http://arxiv.org/abs/1006.4755 , 750kb)

------------------------------------------------------------------------------

\\

arXiv:1006.4798 (*cross-listing*)

Date: Thu, 24 Jun 2010 14:18:09 GMT (2440kb,D)

Title: Variational calculations on multilayer stacks of dipolar Bose-Einstein

condensates

Authors: Andrej Junginger, J\"org Main, G\"unter Wunner

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

Comments: 9 pages, 9 figures

\\

We investigate a multilayer stack of dipolar Bose-Einstein condensates in

terms of a simple Gaussian variational ansatz and demonstrate that this

arrangement is characterized by the existence several stationary states. Using

a Hamiltonian picture we show that in an excited stack there is a coupled

motion of the individual condensates by which they exchange energy. We find

that for high excitations the interaction between the single condensates can

induce the collapse of one of them. We furthermore demonstrate that one

collapse in the stack can force other collapses, too. We discuss the

possibility of experimentally observing the coupled motion and the relevance of

the variational results found to full numerical investigations.

\\ ( http://arxiv.org/abs/1006.4798 , 2440kb)

------------------------------------------------------------------------------

\\

arXiv:1006.4950 (*cross-listing*)

Date: Fri, 25 Jun 2010 09:58:07 GMT (79kb,D)

Title: Mean-field regime of trapped dipolar Bose-Einstein condensates in one

and two dimensions

Authors: Yongyong Cai, Matthias Rosenkranz, Zhen Lei and Weizhu Bao

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

Comments: 9 pages, 5 figures

\\

We derive rigorous one- and two-dimensional mean-field equations for cigar-

and pancake-shaped dipolar Bose-Einstein condensates. We show how the dipolar

interaction modifies the contact interaction of the strongly confined atoms

with arbitrary polarization. In addition, our equations introduce a nonlocal

potential, which is anisotropic for pancake-shaped condensates. We propose to

observe this anisotropy via measurement of the condensate aspect ratio. We also

derive analytically approximate density profiles from our equations. Both the

numerical solutions of our reduced mean-field equations and the analytical

density profiles agree well with numerical solutions of the full

Gross-Pitaevskii equation while being more efficient to compute.

\\ ( http://arxiv.org/abs/1006.4950 , 79kb)

------------------------------------------------------------------------------

\\

arXiv:1006.4965

Date: Fri, 25 Jun 2010 11:30:49 GMT (210kb)

Title: Polarized superfluid state in a three-dimensional fermionic optical

lattice

Authors: A. Koga, J. Bauer, P.Werner, and Th. Pruschke

Categories: cond-mat.quant-gas

Comments: 6 pages, 2 figures

\\

We study ultracold fermionic atoms trapped in a three dimensional optical

lattice by combining the real-space dynamical mean-field approach with

continuous-time quantum Monte Carlo simulations. For a spin-unpolarized system

we show results the density and pair potential profile in the trap for a range

of temperatures. We discuss how a polarized superfluid state is spatially

realized in the spin-polarized system with harmonic confinement at low

temperatures and present the local particle density, local magnetization, and

pair potential.

\\ ( http://arxiv.org/abs/1006.4965 , 210kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5002

Date: Fri, 25 Jun 2010 14:03:39 GMT (78kb)

Title: Are unequal-mass Fermi gases with infinite scattering length universal?

Authors: D. Blume and K. M. Daily

Categories: cond-mat.quant-gas

Comments: 4 pages, 2 figures

\\

We treat small trapped unequal-mass two-component Fermi gases at unitarity

within a non-perturbative microscopic framework and investigate the system

properties as functions of the mass ratio $\kappa$, and the numbers $N_{1}$ and

$N_2$ of heavy and light fermions. While equal-mass Fermi gases with infinitely

large interspecies $s$-wave scattering length $a_s$ are universal, we find that

unequal mass Fermi gases are, for sufficiently large $\kappa$ and in the regime

where Efimov physics is absent, not universal. In particular, the

$(N_1,N_2)=(2,1)$ and $(3,1)$ systems exhibit three-body (3b) and four-body

(4b) resonances at $\kappa = 12.314(2)$ and $10.4(2)$, respectively, as well as

surprisingly large finite-range (FR) effects.

\\ ( http://arxiv.org/abs/1006.5002 , 78kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5148

Date: Sat, 26 Jun 2010 14:49:38 GMT (1176kb,D)

Title: Spin-Orbit Coupled Spinor Bose-Einstein Condensates

Authors: Chunji Wang, Chao Gao, Chao-Ming Jian and Hui Zhai

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

Comments: 4 pages, 4 figures

\\

An effective spin-orbit coupling can be generated in cold atom system by

engineering atom-light interactions. In this letter we study spin-$1/2$ and

spin-$1$ Bose-Einstein condensates with spin-orbit coupling. We find that a

uniform condensate is always unstable and the condensate wave function will

develop non-trivial structures. From numerical simulation we have identified

two different phases. In one phase there is a regular array of vortices

aligning through the center of condensate. In this phase, time-reversal

symmetry is broken and the ground state is two-fold degenerate. In the other

phase the condensate wave function forms a standing wave. The transition

between them is driven by interactions between bosons. We also provide an

analytical understanding of this result and determines the transition point

between these two phases.

\\ ( http://arxiv.org/abs/1006.5148 , 1176kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5167 (*cross-listing*)

Date: Sat, 26 Jun 2010 21:27:55 GMT (192kb)

Title: Demonstration of double EIT using coupled harmonic oscillators and RLC

circuits

Authors: Joshua Harden, Amitabh Joshi, and Juan D. Serna

Categories: quant-ph physics.class-ph physics.ed-ph

Comments: REVTeX, 9 pages, 10 figures

\\

Single and double electromagnetically induced transparency in a medium (EIT),

consisting of four-level atoms in the inverted-Y configuration, are discussed

by using mechanical and electrical analogies. A spring-mass system subject to

damping and driven by an external force is used to represent mechanically the

four-level atom. The equations of motion of this system are solved

analytically, and the revealed single and double EIT studied numerically. On

the other hand, three coupled RLC circuits are used, as the electrical analog,

to explore and demonstrate experimentally single and double EIT. The simplicity

of these two models makes this experiment appropriate for undergraduate

students and easy to incorporate into a college physics laboratory.

\\ ( http://arxiv.org/abs/1006.5167 , 192kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5179

Date: Sun, 27 Jun 2010 02:22:14 GMT (35kb)

Title: Competition between paramagnetism and diamagnetism in charged Fermi

gases

Authors: Xiaoling Jian, Jihong Qin, Qiang Gu

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

Comments: 4 pages, 3 figures

\\

The charged Fermi gas with a small Lande-factor $g$ is expected to be

diamagnetic, while that with a larger $g$ could be paramagnetic. We calculate

the critical value of the $g$-factor which separates the dia- and para-magnetic

regions. In the weak-field limit, $g_{c}$ has the same value both at high and

low temperatures, $g_{c}=1/\sqrt{12}$. Nevertheless, $g_{c}$ increases with the

temperature reducing in finite magnetic fields. We also compare the $g_{c}$

value of Fermi gases with those of Boltzmann and Bose gases, supposing the

particle has three Zeeman levels $\sigma=\pm1, 0$, and find that $g_{c}$ of

Bose and Fermi gases is larger and smaller than that of Boltzmann gases,

respectively.

\\ ( http://arxiv.org/abs/1006.5179 , 35kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5186

Date: Sun, 27 Jun 2010 08:21:14 GMT (14kb)

Title: Heavy-Light Few Fermion Clusters at Unitarity

Authors: S. Gandolfi and J. Carlson

Categories: cond-mat.quant-gas nucl-th

Comments: 4 pages, 2 figures

Report-no: LA-UR 10-04320

\\

We examine the physics of two, three, and four heavy fermions interacting

with a single light fermion via short-range interactions. Four-particle bosonic

Efimov states have proven important experimentally and also been the subject of

significant theoretical effort. Similar fermionic systems are just now being

investigated. We find that with some simple interactions the four- and

five-particle states collapse to the interaction range at smaller mass ratios

than the three-body state, and also before larger clusters can collapse. These

states and their excitations can be studied in cold atom experiments, providing

unique insights into the role of few-body systems in many-body physics.

\\ ( http://arxiv.org/abs/1006.5186 , 14kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5228

Date: Sun, 27 Jun 2010 18:02:00 GMT (117kb)

Title: Glide and Superclimb of Dislocations in Solid $^4$He

Authors: D. Aleinikava, E. Dedits, A.B. Kuklov

Categories: cond-mat.other

Comments: Updated version submitted to JLTP as QFS2010 proceedings; 11 pages, 6

figures

\\

Glide and climb of quantum dislocations under finite external stress,

variation of chemical potential and bias (geometrical slanting) in Peierls

potential are studied by Monte Carlo simulations of the effective string model.

We treat on unified ground quantum effects at finite temperatures $T$. Climb at

low $T$ is assisted by superflow along dislocation core -- {\it superclimb}.

Above some critical stress avalanche-type creation of kinks is found. It is

characterized by hysteretic behavior at low $T$. At finite biases gliding

dislocation remains rough even at lowest $T$ -- the behavior opposite to

non-slanted dislocations. In contrast to glide, superclimb is characterized by

quantum smooth state at low temperatures even for finite bias. In some

intermediate $T$-range giant values of the compressibility as well as

non-Luttinger type behavior of the core superfluid are observed.

\\ ( http://arxiv.org/abs/1006.5228 , 117kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5270 (*cross-listing*)

Date: Mon, 28 Jun 2010 06:25:27 GMT (42kb)

Title: Cyclotron dynamics of cold atoms in 2D optical lattices

Authors: Andrey R. Kolovsky

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

Comments: EPL-style, 8 pages, 4 figures

\\

We propose a simple setup for introducing an artificial magnetic field for

neutral atoms in 2D optical lattices. This setup is based on the phenomenon of

photon-assistent tunneling and involves a low-frequency periodic driving of the

optical lattice. We also address the problem of detecting this effective

magnetic field. In particular, we discuss interference patterns of the atomic

wave function and study the center of mass wave-packet dynamics, which shows

some features of cyclotron dynamics of a classical charged particle.

\\ ( http://arxiv.org/abs/1006.5270 , 42kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5290

Date: Mon, 28 Jun 2010 08:47:59 GMT (195kb)

Title: Features of interaction of microwaves with HeII

Authors: Valery Khodusov and A.S. Naumovets

Categories: cond-mat.other

Comments: 8 pages

\\

Based on interrelation between the thermodynamic and electromechanical

phenomena in superfluid helium, the explanation of experimentally found

features of microwave interaction in the frequency range of 40-200 GHz is

given. Due to fast roton-roton and roton-phonon interactions resonant

excitation on frequency correspond to minimal roton energy relaxes and forms a

wide pedestal. Alongside these fast processes, there are also slower processes

of rotons' scattering by microwave photons taking place, which lead to

additional absorption of energy of resonant microwaves and to the appearance of

a narrow resonant peak on the background of a wide pedestal. The theoretical

explanation of the influence which streams exert on resonant absorption of

microwaves is given. The critical velocity of stream at which absorption of

microwaves was replaced by their radiation is found.

\\ ( http://arxiv.org/abs/1006.5290 , 195kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5312 (*cross-listing*)

Date: Mon, 28 Jun 2010 10:42:53 GMT (34kb)

Title: Dynamics of pair correlations in the attractive Lieb-Liniger gas

Authors: Dominik Muth and Michael Fleischhauer

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

Comments: 4 pages, 4 figures

\\

We investigate the dynamics of a 1D Bose gas after a quench from the

Tonks-Girardeau regime to the regime of strong attractive interactions applying

analytical techniques and exact numerical simulations. After the quench the

system is found to be predominantly in an excited gas-like state, the so-called

super-Tonks gas, however with a small coherent admixture of two-particle bound

states. Despite its small amplitude, the latter component leads to a rather

pronounced oscillation of the local density-density correlation with a

frequency corresponding to the binding energy of the pair, making two-particle

bound states observable in an experiment. Contributions from bound states with

larger particle numbers are found to be negligible.

\\ ( http://arxiv.org/abs/1006.5312 , 34kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5314 (*cross-listing*)

Date: Mon, 28 Jun 2010 11:03:36 GMT (65kb)

Title: Photoassociation of a cold atom-molecule pair: long-range

quadrupole-quadrupole interactions

Authors: M. Lepers, O. Dulieu, and V. Kokoouline

Categories: quant-ph physics.atom-ph physics.chem-ph

Comments: 5 figures

\\

The general formalism of the multipolar expansion of electrostatic

interactions is applied to the calculation the potential energy between an

excited atom and a ground state diatomic molecule at large separations. Both

partners exhibit a permanent quadrupole moment, so that their mutual

quadrupole-quadrupole long-range interaction is attractive enough to bind

trimers. Numerical results are given for an excited Cs(6P) atom and a ground

state Cs2 molecule. The prospects for achieving photoassociation of a cold

atom/dimer pair is thus discussed and found promising. The formalism can be

easily generalized to the long-range interaction between molecules to

investigate the formation of cold tetramers.

\\ ( http://arxiv.org/abs/1006.5314 , 65kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5319

Date: Mon, 28 Jun 2010 11:19:48 GMT (155kb)

Title: Equestion of Two-Fluid Hydrodynamics of Superfluid Helium with the

Account of Electric Fields

Authors: V.D. Khodusov, A.S. Naumovets

Categories: cond-mat.other

Comments: 5 pages

\\

System of two-fluid hydrodynamics of superfluid helium with the account of

electric field is obtained. These equations are obtained in kinetic approach

using quasi-equilibrium distribution function of quasi-particles, which vanishs

collision integral of quasi-particles, and contains dependence on electric

field by means of phenomenological parameter {\alpha}. Using experimental data

at temperature range of 1,4 - 2 K, where basic role plays roton hydrodynamics,

the value of phenomenological parameter, is obtained.

\\ ( http://arxiv.org/abs/1006.5319 , 155kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5519

Date: Tue, 29 Jun 2010 07:37:44 GMT (2133kb)

Title: Nonlinear Scattering of a Bose-Einstein Condensate on a Rectangular

Barrier

Authors: Lincoln D. Carr, Rachel R. Miller, and Daniel R. Bolton

Categories: cond-mat.quant-gas nlin.PS

Comments: 14 pages, 15 figures

\\

We consider the nonlinear scattering and transmission of an atom laser, or

Bose-Einstein condensate (BEC) on a finite rectangular potential barrier. The

nonlinearity inherent in this problem leads to several new physical features

beyond the well-known picture from single-particle quantum mechanics. We find

numerical evidence for a denumerably infinite string of bifurcations in the

transmission resonances as a function of nonlinearity and chemical potential,

when the potential barrier is wide compared to the wavelength of oscillations

in the condensate. Near the bifurcations, we observe extended regions of

near-perfect resonance, in which the barrier is effectively invisible to the

BEC. Unlike in the linear case, it is mainly the barrier width, not the height,

that controls the transmission behavior. We show that the potential barrier can

be used to create and localize a dark soliton or dark soliton train from a

phonon-like standing wave.

\\ ( http://arxiv.org/abs/1006.5519 , 2133kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5540

Date: Tue, 29 Jun 2010 08:35:40 GMT (215kb)

Title: Dynamic Structure Factor of Normal Fermi Gas from Collisionless to

Hydrodynamic Regime

Authors: Shohei Watabe, and Tetsuro Nikuni

Categories: cond-mat.quant-gas

Comments: 19 pages, 9 figures

\\

The dynamic structure factor of a normal Fermi gas is investigated by using

the moment method for the Boltzmann equation. We determine the spectral

function at finite temperatures over the full range of crossover from the

collisionless regime to the hydrodynamic regime. We find that the Brillouin

peak in the dynamic structure factor exhibits a smooth crossover from zero to

first sound as functions of temperature and interaction strength. The dynamic

structure factor obtained using the moment method also exhibits a definite

Rayleigh peak ($/omega /sim 0$), which is a characteristic of the hydrodynamic

regime. We compare the dynamic structure factor obtained by the moment method

with that obtained from the hydrodynamic equations.

\\ ( http://arxiv.org/abs/1006.5540 , 215kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5618

Date: Tue, 29 Jun 2010 13:58:59 GMT (780kb)

Title: Efficient Two-dimensional Subrecoil Raman Cooling of Atoms in a Tripod

Configuration

Authors: Vladimir S. Ivanov, Yuri V. Rozhdestvensky, and Kalle-Antti Suominen

Categories: physics.atom-ph

Comments: 11 pages, 3 figures

\\

We present an efficient method for subrecoil cooling of neutral atoms by

applying Raman cooling in 2D to a four-level tripod-system. The atoms can be

cooled simultaneously in two directions using only three laser beams. We

describe the cooling process with a simple model showing that the momentum

distribution can be rapidly narrowed to velocity spread down to

$0.1v_\text{rec}$, corresponding to effective temperature equal to

$0.01T_\text{rec}$. This method opens new possibilities for cooling of neutral

atoms.

\\ ( http://arxiv.org/abs/1006.5618 , 780kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5642 (*cross-listing*)

Date: Tue, 29 Jun 2010 14:56:05 GMT (282kb,D)

Title: Sympathetic cooling of rovibrationally state-selected molecular ions

Authors: Xin Tong, Alexander H. Winney, Stefan Willitsch

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

\\

We present a new method for the generation of rotationally and vibrationally

state-selected, translationally cold molecular ions in ion traps. Our technique

is based on the state-selective threshold photoionization of neutral molecules

followed by sympathetic cooling of the resulting ions with laser-cooled calcium

ions. Using N$_2^+$ ions as a test system, we achieve > 90 % selectivity in the

preparation of the ground rovibrational level and state lifetimes on the order

of 15 minutes limited by collisions with background-gas molecules. The

technique can be employed to produce a wide range of apolar and polar molecular

ions in the ground and excited rovibrational states. Our approach opens up new

perspectives for cold quantum-controlled ion-molecule-collision studies,

frequency-metrology experiments with state-selected molecular ions and

molecular-ion qubits.

\\ ( http://arxiv.org/abs/1006.5642 , 282kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5664

Date: Tue, 29 Jun 2010 16:16:17 GMT (183kb)

Title: Topological matter with collective encoding and Rydberg blockade

Authors: Anne E. B. Nielsen and Klaus M{\o}lmer

Categories: quant-ph

Comments: 8 pages, 3 figures

\\

We propose to use a permutation symmetric sample of multi-level atoms to

simulate the properties of topologically ordered states. The Rydberg blockade

interaction is used to prepare states of the sample which are equivalent to

resonating valence bond states, Laughlin states, and string-net condensates and

to create and study the properties of their quasi-particle-like fundamental

excitations.

\\ ( http://arxiv.org/abs/1006.5664 , 183kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5805

Date: Wed, 30 Jun 2010 08:39:26 GMT (25kb)

Title: Effective Hamiltonian study of excitations in a boson- fermion mixture

with attraction between components

Authors: A.M. Belemuk, V.N. Ryzhov

Categories: cond-mat.quant-gas

Comments: 9 pages, 5 figures

\\

An effective Hamiltonian for the Bose subsystem in the mixture of ultracold

atomic clouds of bosons and fermions with mutual attractive interaction is used

for investigating collective excitation spectrum. The ground state and mode

frequencies of the $^{87}$Rb and $^{40}$K mixture are analyzed quantitatively

at zero temperature. We find analytically solutions of the hydrodynamics

equations in the Thomas- Fermi approximation. We discuss the relation between

the onset of collapse and collective modes softening and the dependence of

collective oscillations on scattering length and number of boson atoms.

\\ ( http://arxiv.org/abs/1006.5805 , 25kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5825

Date: Wed, 30 Jun 2010 10:03:30 GMT (73kb)

Title: A refined Bogoliubov-Huang approach to helium II thermodynamics

Authors: Jan Ma\'ckowiak, Dawid Borycki

Categories: cond-mat.stat-mech

Comments: 19 pages, 7 figures

\\

The thermodynamics of a free Bose gas with effective temperature scale

$\tilde{T}$ and hard-sphere Bose gas with the $\tilde{T}$ scale are studied.

$\tilde{T}$ arises as the temperature experienced by a single particle in a

quantum gas with 2-body harmonic oscillator interaction $V_\textrm{osc}$, which

at low temperatures is expected to simulate, almost correctly, the attractive

part of the interatomic potential $V_\textrm{He}$ between $^{4}\textrm{He}$

atoms. The repulsive part of $V_\textrm{He}$ is simulated by a hard-sphere (HS)

potential. The resulting system of HS bosons, with the $\tilde{T}$ temperature

scale (HSET), yields good agreement of heat capacity $C_V(T)$ with the

$T<T_\lambda$ branch of experimental $C_V(T)$ $\lambda$-graph observed in

$^{4}\textrm{He}$ and the theoretical BEC transition temperature equals

$T_\lambda=2.17\,\textrm{K}$. Other thermal properties of HSET agree

qualitatively with those of $^{4}\textrm{He}$, but improve those of the free

Bose gas.

\\ ( http://arxiv.org/abs/1006.5825 , 73kb)

------------------------------------------------------------------------------

\\

arXiv:1006.5839

Date: Wed, 30 Jun 2010 12:17:03 GMT (1086kb)

Title: Topological Excitations in Spinor Bose-Einstein Condensates

Authors: Yuki Kawaguchi, Michikazu Kobayashi, Muneto Nitta, Masahito Ueda

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

Comments: Proceedings of the workshop "New Frontiers in QCD 2010"

\\

A rich variety of order parameter manifolds of multicomponent Bose-Einstein

condensates (BECs) admit various kinds of topological excitations, such as

fractional vortices, monopoles, skyrmions, and knots. In this paper, we discuss

two topological excitations in spinor BECs: non-Abelian vortices and knots.

Unlike conventional vortices, non-Abelian vortices neither reconnect themselves

nor pass through each other, but create a rung between them in a topologically

stable manner. We discuss the collision dynamics of non-Abelian vortices in the

cyclic phase of a spin-2 BEC. In the latter part, we show that a knot, which is

a unique topological object characterized by a linking number or a Hopf

invariant [$\pi_3 (S^2)=Z$], can be created using a conventional quadrupole

magnetic field in a cold atomic system.

\\ ( http://arxiv.org/abs/1006.5839 , 1086kb)

------------------------------------------------------------------------------

\\

arXiv:1007.0012

Date: Wed, 30 Jun 2010 20:02:27 GMT (740kb)

Title: Fermi-Hubbard physics with atoms in an optical lattice

Authors: Tilman Esslinger

Categories: cond-mat.quant-gas

Comments: Posted with permission from the Annual Review of of Condensed Matter

Physics Volume 1 \c{opyright} 2010 by Annual Reviews,

http://www.annualreviews.org

\\

The Fermi-Hubbard model is a key concept in condensed matter physics and

provides crucial insights into electronic and magnetic properties of materials.

Yet, the intricate nature of Fermi systems poses a barrier to answer important

questions concerning d-wave superconductivity and quantum magnetism. Recently,

it has become possible to experimentally realize the Fermi-Hubbard model using

a fermionic quantum gas loaded into an optical lattice. In this atomic approach

to the Fermi-Hubbard model the Hamiltonian is a direct result of the optical

lattice potential created by interfering laser fields and short-ranged

ultracold collisions. It provides a route to simulate the physics of the

Hamiltonian and to address open questions and novel challenges of the

underlying many-body system. This review gives an overview of the current

efforts in understanding and realizing experiments with fermionic atoms in

optical lattices and discusses key experiments in the metallic,

band-insulating, superfluid and Mott-insulating regimes.

\\ ( http://arxiv.org/abs/1007.0012 , 740kb)

------------------------------------------------------------------------------

\\

arXiv:1007.0049 (*cross-listing*)

Date: Wed, 30 Jun 2010 23:49:59 GMT (12kb)

Title: Classical phase-space approach for coherent matter waves

Authors: Fran\c{c}ois Impens and David Gu\'ery-Odelin

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

Comments: 5 pages, no figures. Final version

Journal-ref: Phys. Rev. A 81, 065602 (2010)

\\

We investigate a classical phase-space approach of matter-wave propagation

based on the Truncated Wigner Equation (TWE). We show that such description is

suitable for ideal matter waves in quadratic time-dependent confinement as well

as for harmonically trapped Bose Einstein condensates in the Thomas-Fermi

regime. In arbitrary interacting regimes, the TWE combined with the moment

method yields the low-energy spectrum of a condensate as predicted by

independent variational methods. TWE also gives the right breathing mode

frequency for long-ranged interactions decaying as $1/r^2$ in 3D and for a

contact potential in 2D. Quantum signatures, beyond the TWE, may only be found

in the condensate dynamics beyond the regimes of classical phase-space

propagation identified here.

\\ ( http://arxiv.org/abs/1007.0049 , 12kb)

------------------------------------------------------------------------------

\\

arXiv:1007.0059 (*cross-listing*)

Date: Thu, 1 Jul 2010 02:31:41 GMT (1373kb,D)

Title: Suppression of collisional shifts in a strongly interacting lattice

clock

Authors: Matthew D. Swallows, Michael Bishof, Yige Lin, Sebastian Blatt,

Michael J. Martin, Ana Maria Rey, and Jun Ye

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

Comments: 15 pages, 5 figures

\\

Atomic clocks based on neutral atoms confined in optical lattices provide a

unique opportunity for precise studies of quantum many-body systems. The 87Sr

optical lattice clock at JILA has reached an overall fractional frequency

uncertainty of 1x10^-16 [1, 2]. This uncertainty is dominated by two

contributions: atomic collisions and frequency shifts due to room-temperature

blackbody radiation. The density-dependent frequency shift arises from

collisions between fermionic atoms that are subject to slightly inhomogeneous

optical excitation [3, 4]. Several theories of the underlying frequency shift

mechanism have been proposed [5-7]. A three-dimensional optical lattice clock,

where each lattice site contains at most one atom, has been reported [8], and

its collisional shift has been characterized with an uncertainty of 7x10^-16.

Here we present a different and seemingly paradoxical solution to the problem:

by strongly confining atoms in an array of quasi-one-dimensional potentials

formed by a two-dimensional optical lattice, we dramatically increase the

strength of atomic interactions. Instead of an increased collisional shift, we

find that shifts are suppressed in lattice sites containing N > 1 atoms. Strong

interactions introduce an energy gap into the system, and evolution into a

many-body state in which collisions can occur is suppressed. We demonstrate the

effectiveness of this approach by reducing the density-dependent frequency

shift of the JILA lattice clock to the level of 10^-17, reducing the frequency

shift and its uncertainty by more than a factor of ten [1]. This result

demonstrates precise control of interactions in a quantum many-body system,

removing an important obstacle to building optical atomic clocks with large

ensembles of neutral atoms.

\\ ( http://arxiv.org/abs/1007.0059 , 1373kb)

------------------------------------------------------------------------------

\\

arXiv:1007.0073

Date: Thu, 1 Jul 2010 06:04:37 GMT (15kb)

Title: Particle creation in Bose--Einstein condensates: Theoretical formulation

based on conserving gapless mean field theory

Authors: Yasunari Kurita, Michikazu Kobayashi, Hideki Ishihara, Makoto Tsubota

Categories: cond-mat.quant-gas gr-qc

Comments: 9 pages

\\

We formulate particle creation phenomena in Bose--Einstein condensates in

terms of conserving gapless mean field theory for weakly interacting Bose

gases. The particle creation spectrum is calculated by rediagonalizing the

Bogoliubov--de Gennes (BdG) Hamiltonian in mean field theory. The conservation

implies that quasiparticle creation is accompanied by quantum backreaction to

the condensates. Particle creation in this mean field theory is found to be

equivalent to that in quantum field theory (QFT) in curved spacetime. An

expression is obtained for an effective metric affected by quantum

backreaction. The formula for the particle creation spectrum obtained in terms

of QFT in curved spacetime is shown to be the same as that given by

rediagonalizing the BdG Hamiltonian.

\\ ( http://arxiv.org/abs/1007.0073 , 15kb)

------------------------------------------------------------------------------

\\

arXiv:1007.0100 (*cross-listing*)

Date: Thu, 1 Jul 2010 08:30:33 GMT (103kb)

Title: Decoherence effects in Bose-Einstein condensate interferometry. I

General Theory

Authors: B. J. Dalton

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

Comments: Full version of paper, including all Appendices. Journal version only

includes Appendix A

\\

The present paper outlines a basic theoretical treatment of decoherence and

dephasing effects in interferometry based on single component BEC in double

potential wells, where two condensate modes may be involved. Results for both

two mode condensates and the simpler single mode condensate case are presented.

A hybrid phase space distribution functional method is used where the

condensate modes are described via a truncated Wigner representation, and the

basically unoccupied non-condensate modes are described via a positive P

representation. The Hamiltonian for the system is described in terms of quantum

field operators for the condensate and non-condensate modes. The functional

Fokker-Planck equation for the double phase space distribution functional is

derived. Equivalent Ito stochastic equations for the condensate and

non-condensate fields that replace the field operators are obtained, and

stochastic averages of products of these fields give the quantum correlation

functions used to interpret interferometry experiments. The stochastic field

equations are the sum of a deterministic term obtained from the drift vector in

the functional Fokker-Planck equation, and a noise field whose stochastic

properties are determined from the diffusion matrix in the functional

Fokker-Planck equation. The noise field stochastic properties are similar to

those for Gaussian-Markov processes in that the stochastic averages of odd

numbers of noise fields are zero and those for even numbers of noise field

terms are sums of products of stochastic averages associated with pairs of

noise fields. However each pair is represented by an element of the diffusion

matrix rather than products of the noise fields themselves. The treatment

starts from a generalised mean field theory for two condensate mode. The

generalized mean field theory solutions are needed for calculations using the

Ito stochastic field equations.

\\ ( http://arxiv.org/abs/1007.0100 , 103kb)

------------------------------------------------------------------------------

\\

arXiv:1007.0116

Date: Thu, 1 Jul 2010 10:04:58 GMT (2302kb)

Title: Cavity QED with an ultracold ensemble on a chip: observing strong

magnetic coupling at finite temperatures

Authors: Kathrin Henschel, Helmut Ritsch, Johannes Majer and J\"org

Schmiedmayer

Categories: quant-ph

Comments: 20 pages, 18 figures

\\

We study the nonlinear dynamics of an ensemble of cold trapped atoms with a

hyperfine transition magnetically coupled to a resonant microwave cavity mode.

Despite the minute single atom coupling one obtains strong coupling between

collective hyperfine qubits and microwave photons enabling coherent transfer of

an excitation between the long lived atomic qubit state and the mode. Evidence

of strong coupling can be obtained from the cavity transmission spectrum even

at finite thermal photon number. The system allows to study further prominent

collective phenomena as superradiant decay of an inverted ensemble or building

a narrowband stripline micromaser locked to an atomic hyperfine transition.

\\ ( http://arxiv.org/abs/1007.0116 , 2302kb)

------------------------------------------------------------------------------

\\

arXiv:1007.0153 (*cross-listing*)

Date: Thu, 1 Jul 2010 12:53:54 GMT (379kb)

Title: Simulating pasta phases by molecular dynamics and cold atoms ---

Formation in supernovae and superfluid neutrons in neutron stars

Authors: Gentaro Watanabe

Categories: nucl-th astro-ph.SR cond-mat.quant-gas

Comments: 6 pages, 2 figures, to appear in Proceedings of the workshop "New

Frontiers in QCD 2010" (NFQCD2010)

\\

In dense stars such as collapsing cores of supernovae and neutron stars,

nuclear "pasta" such as rod-like and slab-like nuclei are speculated to exist.

However, whether or not they are actually formed in supernova cores is still

unclear. Here we solve this problem by demonstrating that a lattice of rod-like

nuclei is formed from a bcc lattice by compression. We also find that the

formation process is triggered by an attractive force between nearest neighbor

nuclei, which starts to act when their density profile overlaps, rather than

the fission instability. We also discuss the connection between pasta phases in

neutron star crusts and ultracold Fermi gases.

\\ ( http://arxiv.org/abs/1007.0153 , 379kb)

------------------------------------------------------------------------------

\\

arXiv:1007.0161

Date: Thu, 1 Jul 2010 13:24:58 GMT (1073kb)

Title: Properties of Vacancy Formation in He-4 hcp Crystals at Zero Temperature

and Fixed Pressure

Authors: Y. Lutsyshyn, C. Cazorla, G. E. Astrakharchik, and J. Boronat

Categories: cond-mat.other

\\

Equation of state of He-4 hcp crystals with vacancies is determined at zero

temperature using the diffusion Monte Carlo technique, an exact ground state

zero-temperature method. This allows us to extract the formation enthalpy and

isobaric formation energy of a single vacancy in otherwise perfect helium

solid. Results were obtained for pressures up to 160 bar. The isobaric

formation energy is found to reach a minimum near 57 bar where it is equal to

$10.5\pm 1.2$ K. At the same pressure, the vacancy formation volume exhibits a

maximum and reaches the volume of the unit cell. This pressure coincides with

the pressure interval over which a peak in the supersolid fraction of He-4 was

observed in a recent experiment.

\\ ( http://arxiv.org/abs/1007.0161 , 1073kb)

------------------------------------------------------------------------------

The replacements:

------------------------------------------------------------------------------

\\

arXiv:quant-ph/0601212

replaced with revised version Fri, 25 Jun 2010 05:43:26 GMT (344kb)

Title: Thermodynamics analogue for self-trapped spinning-stationary Madelung

fluid

Authors: Agung Budiyono

Categories: quant-ph

Comments: changed content, Revtex 17 pages

\\ ( http://arxiv.org/abs/quant-ph/0601212 , 344kb)

------------------------------------------------------------------------------

\\

arXiv:0910.5948

replaced with revised version Fri, 25 Jun 2010 07:07:59 GMT (248kb)

Title: Hyper-Ramsey Spectroscopy of Optical Clock Transitions

Authors: V. I. Yudin, A. V. Taichenachev, C. W. Oates, Z. W. Barber, N. D.

Lemke, A. D. Ludlow, U. Sterr, Ch. Lisdat, and F. Riehle

Categories: physics.atom-ph physics.optics

Comments: 5 pages, 4 figures

\\ ( http://arxiv.org/abs/0910.5948 , 248kb)

------------------------------------------------------------------------------

\\

arXiv:0912.0355

replaced with revised version Sun, 27 Jun 2010 08:26:23 GMT (810kb,D)

Title: Bogoliubov Theory and Lee-Huang-Yang Corrections in Spin-1 and Spin-2

Bose-Einstein Condensates in the Presence of the Quadratic Zeeman Effect

Authors: Shun Uchino, Michikazu Kobayashi, and Masahito Ueda

Categories: cond-mat.quant-gas nucl-th

Comments: v3: 62 pages, 18 figures

Journal-ref: Phys. Rev. A 81, 063632 (2010)

DOI: 10.1103/PhysRevA.81.063632

\\ ( http://arxiv.org/abs/0912.0355 , 810kb)

------------------------------------------------------------------------------

\\

arXiv:1001.3200

replaced with revised version Mon, 28 Jun 2010 03:22:38 GMT (478kb,D)

Title: Universal behavior of pair correlations in a strongly interacting Fermi

gas

Authors: E. D. Kuhnle, H. Hu, X.-J. Liu, P. Dyke, M. Mark, P. D. Drummond, P.

Hannaford, and C. J. Vale

Categories: cond-mat.quant-gas

Comments: Manuscript revised, 4 pages, 3 figures

\\ ( http://arxiv.org/abs/1001.3200 , 478kb)

------------------------------------------------------------------------------

\\

arXiv:1006.4734

replaced with revised version Mon, 28 Jun 2010 14:20:26 GMT (1652kb)

Title: Groundstate and Collective Modes of a Spin-Polarized Dipolar

Bose-Einstein Condensate in a Harmonic Trap

Authors: I. Sapina, T. Dahm and N. Schopohl

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

Comments: Changes to previous version: Fig. 7 and Fig. 8 re-plotted in

compatible pdf-format and one reference added (Ref. [7])

\\ ( http://arxiv.org/abs/1006.4734 , 1652kb)

------------------------------------------------------------------------------

\\

arXiv:1004.5241

replaced with revised version Mon, 28 Jun 2010 14:45:16 GMT (60kb)

Title: Numerical solution of the Boltzmann equation for the collective modes of

trapped Fermi gases

Authors: T.Lepers, D.Davesne, S.Chiacchiera and M.Urban

Categories: cond-mat.quant-gas nucl-th

Comments: 13 pages, 8 figures, accepted for publication in Phys. Rev. A

\\ ( http://arxiv.org/abs/1004.5241 , 60kb)

------------------------------------------------------------------------------

\\

arXiv:1005.0357

replaced with revised version Mon, 28 Jun 2010 16:05:15 GMT (513kb)

Title: Comparison between two mobile absolute gravimeters: optical versus

atomic interferometers

Authors: S. Merlet, Q. Bodart, N. Malossi, A. Landragin, F. Pereira Dos Santos,

O. Gitlein, L. Timmen

Categories: physics.atom-ph physics.geo-ph

Journal-ref: Metrologia 47 (2010) L9-L11

DOI: 10.1088/0026-1394/47/4/L01

\\ ( http://arxiv.org/abs/1005.0357 , 513kb)

------------------------------------------------------------------------------

\\

arXiv:1006.3893

replaced with revised version Mon, 28 Jun 2010 21:10:10 GMT (256kb)

Title: The Nonlinear Dirac Equation in Bose-Einstein Condensates: Relativistic

Linear Stability Equations, Nonlinear Localized Modes, and Cherenkov

Radiation

Authors: L. H. Haddad and L. D. Carr

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

Comments: 5 pages, 2 figures

\\ ( http://arxiv.org/abs/1006.3893 , 256kb)

------------------------------------------------------------------------------

\\

arXiv:0912.1589

replaced with revised version Tue, 29 Jun 2010 12:17:16 GMT (460kb,D)

Title: Resonant Superfluidity in an Optical Lattice

Authors: I. Titvinidze, M. Snoek and W. Hofstetter

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

Comments: 19 pages, 3 figures

Journal-ref: New J. Phys. 12 (2010) 065030

DOI: 10.1088/1367-2630/12/6/065030

\\ ( http://arxiv.org/abs/0912.1589 , 460kb)

------------------------------------------------------------------------------

\\

arXiv:1004.0701

replaced with revised version Tue, 29 Jun 2010 21:39:35 GMT (137kb)

Title: Interacting Hofstadter spectrum of atoms in an artificial gauge field

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

Categories: cond-mat.quant-gas

Comments: 4+ pages, 2 figures; v2: published version

Journal-ref: Phys. Rev. Lett. 104, 255303 (2010)

DOI: 10.1103/PhysRevLett.104.255303

\\ ( http://arxiv.org/abs/1004.0701 , 137kb)

------------------------------------------------------------------------------

\\

arXiv:1005.5050

replaced with revised version Thu, 1 Jul 2010 14:57:20 GMT (847kb)

Title: Nonequivalence of ensembles in the Curie-Weiss anisotropic quantum

Heisenberg model

Authors: Michael Kastner

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

Comments: 23 pages, 3 figures

Journal-ref: J. Stat. Mech. (2010) P07006

DOI: 10.1088/1742-5468/2010/07/P07006

\\ ( http://arxiv.org/abs/1005.5050 , 847kb)

------------------------------------------------------------------------------

\\

arXiv:1001.4167

replaced with revised version Thu, 1 Jul 2010 17:24:40 GMT (478kb)

Title: Unconventional magnetism in imbalanced Fermi systems with magnetic

dipolar interactions

Authors: Benjamin M. Fregoso and Eduardo Fradkin

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

Comments: 10 pages, 6 figures(2 subfigures); 4 appendices. Version published in

Physical Review B

Journal-ref: Phys. Rev. B 81, 214443 (2010) [9 pages]

DOI: 10.1103/PhysRevB.81.214443

\\ ( http://arxiv.org/abs/1001.4167 , 478kb)

------------------------------------------------------------------------------

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 Wed Sep 01 2010 - 11:01:37 EST

*
This archive was generated by hypermail 2.2.0
: Wed Sep 01 2010 - 11:01:48 EST
*