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

Date: Thu, 05 Nov 2009 20:48:07 +1000

Date: Thu, 05 Nov 2009 20:48:07 +1000

Dear subscribers,

This week's email was collated by Mike Garrett. There are 32 new preprints and

17 replacements.

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arXiv:0909.3357

Date: Fri, 18 Sep 2009 06:03:31 GMT (104kb)

Title: Reentrance of Bose-Einstein condensation in spinor atomic gases in

magnetic field

Authors: Chengjun Tao, Zhirong Jiao, and Qiang Gu

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

Comments: 6 pages, 6 figures

\\

We calculate the Bose-Einstein condensation (BEC) temperature of spin-1

atomic bosons in external magnetic field, taking into account the influence of

the quadratic Zeeman effect. In case that the quadratic Zeeman coefficient is

positive, the BEC temperature exhibits a nontrivial dependance on the magnetic

field and a magnetic-field-induced reentrant phenomenon of BEC is observed.

This phenomenon could be well understood by the competition between the linear

and quadratic Zeeman effects. Reentrance of BEC in a trapped spinor Bose gas is

also discussed.

\\ ( http://arxiv.org/abs/0909.3357 , 104kb)

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arXiv:0909.3455

Date: Fri, 18 Sep 2009 14:55:58 GMT (304kb,D)

Title: Sound propagation in a Bose-Einstein condensate at finite temperatures

Authors: R. Meppelink, S.B. Koller, and P. van der Straten

Categories: cond-mat.quant-gas

\\

We study the propagation of a density wave in a magnetically trapped

Bose-Einstein condensate at finite temperatures. The thermal cloud is in the

hydrodynamic regime and the system is therefore described by the two-fluid

model. A phase-contrast imaging technique is used to image the cloud of atoms

and allows us to observe small density excitations. The propagation of the

density wave in the condensate is used to determine the speed of sound as a

function of the temperature. We find the speed of sound to be in good agreement

with calculations based on the Landau two-fluid model.

\\ ( http://arxiv.org/abs/0909.3455 , 304kb)

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arXiv:0909.3501

Date: Fri, 18 Sep 2009 18:51:10 GMT (386kb)

Title: Metastable states and macroscopic quantum tunneling in a cold atom

Josephson ring

Authors: Dmitry Solenov, Dmitry Mozyrsky

Categories: cond-mat.quant-gas

Comments: 4 pages, 2 figures

\\

We study macroscopic properties of a system of weakly interacting neutral

bosons confined in a ring-shaped potential with a Josephson junction. We derive

an effective low energy action for this system and evaluate its properties. In

particular we find that the system possesses a set of metastable

current-carrying states and evaluate the rates of transitions between these

states due to macroscopic quantum tunneling. Finally we discuss signatures of

different metastable states in the time-of-flight images and argue that the

effect is observable within currently available experimental technique.

\\ ( http://arxiv.org/abs/0909.3501 , 386kb)

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arXiv:0909.3322

Date: Thu, 17 Sep 2009 21:32:10 GMT (1024kb)

Title: Analytic Approximation of the Tavis-Cummings Ground State via Projected

States

Authors: Octavio Castanos, Eduardo Nahmad-Achar, Ramon Lopez-Pena, and Jorge G.

Hirsch

Categories: quant-ph

Comments: 22 pages, 13 figures, accepted for publication in Physics Scripta

\\

We show that an excellent approximation to the exact quantum solution of the

ground state of the Tavis-Cummings model is obtained by means of a

semi-classical projected state. This state has an analytical form in terms of

the model parameters and, in contrast to the exact quantum state, it allows for

an analytical calculation of the expectation values of field and matter

observables, entanglement entropy between field and matter, squeezing

parameter, and population probability distributions. The fidelity between this

projected state and the exact quantum ground state is very close to 1, except

for the region of classical phase transitions. We compare the analytical

results with those of the exact solution obtained through the direct

Hamiltonian diagonalization as a function of the atomic separation energy and

the matter-field coupling.

\\ ( http://arxiv.org/abs/0909.3322 , 1024kb)

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arXiv:0909.3430

Date: Fri, 18 Sep 2009 13:18:22 GMT (619kb)

Title: Towards Bose-Einstein condensation of excitons in an asymmetric

multi-quantum state magnetic lattice

Authors: A. Abdelrahman, M. Vasiliev, K. Alameh, P. Hannaford, Byoung S. Ham,

and Yong-Tak Lee

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

Comments: Conference Paper: NUSOD 2009

\\

An asymmetric multi-quantum state magnetic lattice is proposed to host

excitons formed in a quantum degenerate gas of ultracold fermionic atoms to

simulate Bose-Einstein condensation (BEC) of excitons. A Quasi-two dimensional

degenerate gas of excitons can be collected in the in-plane asymmetric magnetic

bands created at the surface of the proposed magnetic lattice, where the

ultracold fermions simulate separately direct and indirect confined

electronhole pairs (spin up fermions-spin down fermions) rising to the

statistically degenerate Bose gas and eventually through controlled tunnelling

to BEC of excitons. The confinement of the coupled magnetic quantum well

(CMQWs) system may significantly improve the condition for long lived exciton

BEC. The exciton BEC, formed in CMQWs can be regarded as a suitable host for

the multi-qubits (multipartite) systems to be used in quantum information

processors.

\\ ( http://arxiv.org/abs/0909.3430 , 619kb)

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arXiv:0909.3433

Date: Fri, 18 Sep 2009 13:30:41 GMT (543kb)

Title: Multipartite Entanglement in a Discrete Magnetic Bands Magnetic Lattice

Authors: A. Abdelrahman, P. Hannaford, M. Vasiliev and K. Alameh

Categories: quant-ph

Comments: Conference Paper:Asia Communications and Photonics Conference and

Exhibition (ACP)

\\

Using magneto-optical materials, an asymmetric multi-quantum state magnetic

lattice is proposed to host an entangled multipartite system formed by using a

quantum degenerate gas of ultracold atoms in a Bose Einstein Condensate (BEC).

The discrete magnetic bands magnetic lattice is devised to locate a

controllable long-range entanglement of a many harmonic oscillator system well

separated in space. The confinement of the coupled magnetic quantum well (CMQW)

system may significantly improve the condition for the long-range entanglement

of the multipartite (multi-qubits) to be used in quantum information

processors.

\\ ( http://arxiv.org/abs/0909.3433 , 543kb)

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arXiv:0909.3439

Date: Fri, 18 Sep 2009 13:53:02 GMT (30kb)

Title: Optimized Dynamical Decoupling for Power Law Noise Spectra

Authors: S. Pasini and G.S. Uhrig

Categories: quant-ph

Comments: 9 pages, 5 figures

\\

We analyze the suppression of decoherence by means of dynamical decoupling in

the pure-dephasing spin-boson model for baths with power law spectra. The

sequence of ideal $\pi$ pulses is optimized according to the power of the bath.

We expand the decoherence function and separate the cancelling divergences from

the relevant terms. The proposed sequence is chosen to be the one minimizing

the decoherence function. By construction, it provides the best performance. We

analytically derive the conditions that must be satisfied. The resulting

equations are solved numerically. The solutions are very close to the

Carr-Purcell-Meiboom-Gill (CPMG) sequence for a soft cutoff of the bath while

they approach the Uhrig dynamical-decoupling (UDD) sequence as the cutoff

becomes harder.

\\ ( http://arxiv.org/abs/0909.3439 , 30kb)

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arXiv:0909.3543

Date: Fri, 18 Sep 2009 22:37:58 GMT (737kb,D)

Title: Pure Mott phases in confined ultra-cold atomic systems

Authors: V.G. Rousseau, G.G. Batrouni, D.E. Sheehy, J. Moreno, and M. Jarrell

Categories: cond-mat.quant-gas

Comments: 4 Pages, 6 figures

\\

We propose a novel scheme for confining atoms to optical lattices by

engineering a spatially-inhomogeneous hopping matrix element in the

Hubbard-model (HM) description, a situation we term off-diagonal confinement

(ODC). We show, via an exact numerical solution of the boson HM with ODC, that

this scheme possesses distinct advantages over the conventional method of

confining atoms using an additional trapping potential, including the presence

of incompressible Mott phases at commensurate filling and a phase diagram that

is similar to the uniform HM. The experimental implementation of ODC will thus

allow a more faithful realization of correlated phases of interest in cold atom

experiments.

\\ ( http://arxiv.org/abs/0909.3543 , 737kb)

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arXiv:0909.3563

Date: Mon, 21 Sep 2009 11:08:56 GMT (429kb)

Title: Study of Kosterlitz-Thouless transition of Bose systems governed by a

random potential using quantum Monte Carlo simulations

Authors: Hiroki Kuroyanagi, Mitsuaki Tsukamoto and Makoto Tsubota

Categories: cond-mat.stat-mech

Comments: 6 pages, 11 figures

\\

We study the effects of a random potential on Kosterlitz-Thouless (KT)

transitions in two-dimensional Bose systems by means of quantum Monte Carlo

simulation. We use the Bose-Hubbard model imposed on the hard-core limit. The

potential differs among different sites, whose distribution is assumed to obey

a Gaussian distribution. Calculating the superfluid density, the specific heat

and the correlation functions leads to a superfluid-disordered phase diagram.

As the potential becomes more random, the KT transition temperature reduces,

but the superfluid phase survives for broad values of the randomness. Our work

is related to recent experiments as $^4$He in porous materials and disordered

cold atomic gases.

\\ ( http://arxiv.org/abs/0909.3563 , 429kb)

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arXiv:0909.3693

Date: Mon, 21 Sep 2009 06:09:15 GMT (49kb)

Title: Density matrix renormalization group for bosonic quantum Hall effect

Authors: D. L. Kovrizhin

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

Comments: 8 pages, 7 figures

\\

We developed a new Density Matrix Renormalization Group technique to study

quantum Hall fractions of fast rotating bosons. In this paper we present a

discussion of the method together with the results which we obtain in three

distinct cases of the narrow channel, cylinder and spherical geometries. In the

narrow channel case, which is relevant to anisotropic confining traps in the

limit of extremely fast rotation, we find a series of zero-temperature phase

transitions in the strongly interacting regime as a function of the interaction

strength between bosons. We compute energies and density profiles for different

filling fractions on a cylinder and compare the convergence rates of the method

in the cylinder and a sphere geometries.

\\ ( http://arxiv.org/abs/0909.3693 , 49kb)

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arXiv:0909.3762

Date: Mon, 21 Sep 2009 13:09:45 GMT (163kb)

Title: Hierarchical theory of quantum dissipation: Partial fraction

decomposition scheme

Authors: Jian Xu, Rui-Xue Xu, Meng Luo, and YiJing Yan

Categories: cond-mat.stat-mech

Comments: 8 pages, 3 figures

\\

We propose a partial fraction decomposition scheme to the construction of

hierarchical equations of motion theory for bosonic quantum dissipation

systems. The expansion of Bose--Einstein function in this scheme shows similar

properties as it applies for Fermi function. The performance of the resulting

quantum dissipation theory is exemplified with spin--boson systems. In all

cases we have tested the new theory performs much better, about an order of

magnitude faster, than the best available conventional theory based on

Matsubara spectral decomposition scheme.

\\ ( http://arxiv.org/abs/0909.3762 , 163kb)

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arXiv:0909.3775

Date: Mon, 21 Sep 2009 14:01:50 GMT (196kb)

Title: Statistics of a Free Single Quantum Particle at a Finite Temperature

Authors: Jian-Ping Peng

Categories: cond-mat.stat-mech

Comments: 9 pages, 2figures

\\

We present a model to study the statistics of a single structureless quantum

particle freely moving in a space at a finite temperature. It is shown that the

quantum particle feels the temperature and can exchange energy with its

environment in the form of heat transfer. The underlying mechanism is

diffraction at the edge of the wave front of its matter wave. Within the

framework of modern quantum and statistical mechanics, analytical expressions

are obtained for an exact description of the whole irreversible process.

\\ ( http://arxiv.org/abs/0909.3775 , 196kb)

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arXiv:0909.3799

Date: Mon, 21 Sep 2009 15:13:33 GMT (9kb)

Title: Motion of a Vortex Filament in Superfluid 4He: Effects of Friction Force

in the Hall-Vinen Phenomenological Model

Authors: Bhimsen K. Shivamoggi

Categories: cond-mat.other

\\

Motion of a vortex filament in superfluid 4He is considered by using the

Hall-Vinen phenomenological model for the scattering process between the vortex

and thermal excitations in liquid 4He. Hall-Vinen equations are formulated

first in the intrinsic geometric parameter space to obtain insights (like the

fundamental importance of one aspect of the friction term, associated with the

friction coefficient alpha, in the Hall-Vinen notation, as well as a proper

rationale for the previous neglect of the other aspect of the friction term,

associated with the friction coefficient alpha^prime) into the underlying

physical features as well as highlight difficulties in making further progress

on this route. A reformulation of the Hall-Vinen equation in the extrinsic

vortex filament coordinate space is then shown to provide a useful alternative

approach in this regard. Though the friction term associated with alpha, for

very small alpha, has little capacity to make significant contribution to the

vortex motion in a quantitative way it appears to be able to change the vortex

motion aspects in a quantitative way.

\\ ( http://arxiv.org/abs/0909.3799 , 9kb)

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arXiv:0909.3819

Date: Mon, 21 Sep 2009 17:13:21 GMT (1757kb,D)

Title: Delocalization to self-trapping transition of a Bose fluid confined in a

double well potential. An analysis via one- and two-body correlation

properties

Authors: S. F. Caballero Benitez, V. Romero-Rochin, and R. Paredes

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

Comments: 16 pages, 9 figures

\\

We revisit the coherent or delocalized to self-trapping transition in an

interacting bosonic quantum fluid confined in a double well potential, in the

context of full quantum calculations. We show that an $N$-particle Bose-Hubbard

fluid reaches an stationary state through the two-body interactions. These

stationary states are either delocalized or self-trapped in one of the wells,

the former appearing as coherent oscillations in the mean-field approximation.

By studying one- and two-body properties in the energy eigenstates and in a set

of coherent states, we show that the delocalized to self-trapped transition

occurs as a function of the energy of the fluid, provided the interparticle

interaction is above a critical or threshold value. We argue that this is a

type of symmetry-breaking continuous phase transition.

\\ ( http://arxiv.org/abs/0909.3819 , 1757kb)

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arXiv:0909.3825

Date: Mon, 21 Sep 2009 17:55:30 GMT (197kb)

Title: Clock shifts of optical transitions in ultracold atomic gases

Authors: Zhenhua Yu, C.J. Pethick

Categories: cond-mat.quant-gas

Comments: 4 pages, 1 figure, NORDITA-2009-58

\\

We calculate the shift, due to interatomic interactions, of an optical

transition in an atomic Fermi gas trapped in an optical lattice, as in recent

experiments of Campbell {\it et al.}, Science {\bf 324}, 360 (2009). Using a

pseudospin formalism to describe the density matrix of the internal two states

of the optical transition, we derive a Bloch equation which incorporates both

the spatial inhomogeneity of the probe laser field and the interatomic

interactions. Expressions are given for the frequency shift as a function of

the pulse duration, detuning of the probe laser, and the spatial dependence of

the electric field of the probe beam. In the low temperature semiclassical

regime, we find that the magnitude of the shift is proportional to the

temperature.

\\ ( http://arxiv.org/abs/0909.3825 , 197kb)

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arXiv:0909.3644

Date: Sun, 20 Sep 2009 17:14:41 GMT (699kb)

Title: Hyperfine structure in the microwave spectra of ultracold polar

molecules

Authors: Hong Ran, J. Aldegunde, Jeremy M. Hutson

Categories: physics.chem-ph quant-ph

\\

We investigate the microwave spectra of ultracold alkali metal dimers in

magnetic, electric and combined fields, taking account of the hyperfine

structure due to the nuclear spins. We consider the molecules 41K87Rb and

7Li133Cs, which are the targets of current experiments and demonstrate two

extremes of large and small nuclear quadrupole coupling. We calculate the

frequencies and intensities of transitions that may be used to transfer

ultracold molecules between hyperfine states in a magnetic field, employing

different polarizations of microwave radiation. In an electric field, the

hyperfine levels display narrow avoided crossings at specific fields that we

explain in terms of molecular alignment. The hyperfine splittings that arise in

electric fields may hinder individual addressing in schemes to use ultracold

molecules in quantum computation, but the structure of the spectra is

suppressed in combined fields.

\\ ( http://arxiv.org/abs/0909.3644 , 699kb)

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arXiv:0909.3851

Date: Mon, 21 Sep 2009 20:01:03 GMT (393kb)

Title: Coreless vorticity in multicomponent Bose and Fermi superfluids

Authors: G. Catelani, E. A. Yuzbashyan

Categories: cond-mat.quant-gas

Comments: 7 pages, 4 figures

\\

We consider quantized vortices in two-component Bose-Einstein condensates and

three-component Fermi gases with attractive interactions. In these systems, the

vortex core can be either empty (normal in the fermion case) or filled with

another superfluid. We determine critical values of the parameters -- chemical

potentials, scattering lengths and, for Fermi gases, temperature -- at which a

phase transition between the two types of vortices occurs. Population imbalance

can lead to superfluid core (coreless) vorticity in multicomponent superfluids

which otherwise support only usual vortices. For multicomponent Fermi gases, we

construct the phase diagram including regions of coreless vorticity. We extend

our results to trapped bosons and fermions using an appropriate local

approximation, which goes beyond the usual Thomas-Fermi approximation for

trapped bosons.

\\ ( http://arxiv.org/abs/0909.3851 , 393kb)

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arXiv:0909.3920

Date: Tue, 22 Sep 2009 06:53:35 GMT (10kb)

Title: Gross-Pitaevskii Equation for a System of Randomly Interacting Cold

Bosons

Authors: J. van Baardewijk

Categories: cond-mat.dis-nn cond-mat.stat-mech

Comments: 6 pages

\\

Random interaction models have been successful in describing the amorphous

properties of solids such as spin-glasses and structural glasses. This

modelling approach is applied to a system of zero-spin cold bosons moving in an

amorphous environment. The bosons are given to interact according to a

non-random hard-core interaction. Additionally the bosons are subjected to a

random interaction potential similar to that used for glasses. The approach is

to apply a combination of replica methods and field theoretic techniques

developed for superfluid Bose systems. This leads to an equation for the

low-temperature Bose-Einstein condensate which is derived in the Hartree-Fock

approximation. The equation is similar to the Gross-Pitaevskii equation, but

the hard-core coupling constant is renormalised by the presence of the random

interactions in a position dependent way. The amorphous contribution contains

the replica diagonal and off-diagonal Green's functions, for which the Dyson

equations are formulated.

\\ ( http://arxiv.org/abs/0909.3920 , 10kb)

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arXiv:0909.3937

Date: Tue, 22 Sep 2009 10:09:28 GMT (100kb)

Title: Gauge-Away Effect in Cold Gases on Optical Lattices

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

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

Comments: 4 pages, 2 figures, revtex style

\\

It is shown that a simple modification of the geometry in which Raman lasers

are applied to a cold gas in an optical lattice results in transforming the

emerging effective electromagnetic field into a pure gauge. This contrived

gauge-away effect can be observed experimentally by measuring the

Mott-Insulator to Superfluid critical point. The underlying mechanism for this

phenomenon is the ability to engineer the transfer of the transverse component

of the gauge potential into its longitudinal one.

\\ ( http://arxiv.org/abs/0909.3937 , 100kb)

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arXiv:0909.3996

Date: Tue, 22 Sep 2009 13:49:25 GMT (346kb)

Title: Supersymmetric Response of Bose-Fermi Mixture to Photoassociation

Authors: T. Shi, Yue Yu, and C. P. Sun

Categories: cond-mat.other

Comments: 5 pages, 3 figures

\\

We study supersymmetric (SUSY) responses to a photoassociation process in a

mixture of Bose molecules $b$ and Fermi atoms $f$ which turn to mutual

superpartners for a set of proper parameters. We consider the molecule $b$ to

be a bound state of the atom $f$ and another Fermi atom $F$ with different

species. The $b$-$f$ mixture and a free $F$ atom gas are loaded in an optical

lattice. The SUSY nature of the mixture can be signaled in the response to a

photon induced atom-molecule transition: While two new types of fermionic

excitations, an individual $b$ particle-$f$ hole pair continuum and the

Goldstino-like collective mode, are concomitant for a generic $b$-$f$ mixture,

the former is completely suppressed in the SUSY $b$-$f$ mixture and the

zero-momentum mode of the latter approaches to an exact eigenstate. This SUSY

response can be detected by means of the spectroscopy method, e.g., the

photoassociation spectrum which displays the molecular formation rate of $%

Ff\to b$.

\\ ( http://arxiv.org/abs/0909.3996 , 346kb)

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arXiv:0909.4056

Date: Tue, 22 Sep 2009 18:01:37 GMT (258kb,D)

Title: Weakly Bound Cluster States of Efimov Character

Authors: Javier von Stecher

Categories: cond-mat.quant-gas

Comments: 4+ pages, 3 figures

\\

We study the behavior of weakly bound clusters and their relation to the

well-known three-body Efimov states. We propose a model Hamiltonian that allows

the independent control of two- and three-body physics. To test the validity of

the model potential, we reproduce predictions of three- and four-body universal

states. Then we extend our study to larger cluster systems by combining

numerical techniques such as correlated-Gaussian and diffusion Monte Carlo

methods. We identify a series of universal cluster states that can be

qualitatively interpreted as adding one particle at a time to an Efimov trimer.

Experimental signatures of these cluster states are discussed.

\\ ( http://arxiv.org/abs/0909.4056 , 258kb)

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arXiv:0909.3958

Date: Tue, 22 Sep 2009 11:06:31 GMT (213kb)

Title: Geomeric phases in Quantum Mechanics

Authors: Y.Ben-Aryeh

Categories: quant-ph

Comments: 31 pages

\\

Various phenomena related to geometric phases in quantum mechanics are

reviewed and explained by analyzing some examples.The concepts of 'parallelism'

,'connections' and 'curvatures' are applied to Aharonov-Bohm (AB) effect, to

U(1)phase rotation, to SU(2) phase rotation and to holonomic quantum

computation (HQC). The connections in Schrodinger equations are treated by two

alternative approaches. Implementation of HQC is demonstrated by the use of

'dark states' including detailed calculations with the connections, for

implementing the quantum gates. 'Anyons' are related to the symmetries of the

wave functions,in a two-dimensional space, and the use of this concept is

demonstrated by analyzing an example taken from the field of Quantum Hall

effects.

\\ ( http://arxiv.org/abs/0909.3958 , 213kb)

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arXiv:0909.4072

Date: Tue, 22 Sep 2009 20:59:52 GMT (2369kb)

Title: Vortex Synchronization in Bose-Einstein Condensates: A Time-Dependent

Gross-Pitaevskii Equation Approach

Authors: Ryan Barnett, Edward Chen, and Gil Refael

Categories: cond-mat.quant-gas

Comments: 6.1 pages, 3 figures

\\

In this work we consider vortex lattices in rotating Bose-Einstein

Condensates composed of two species of bosons having different masses.

Previously [1] it was claimed that the vortices of the two species form bound

pairs and the two vortex lattices lock. Remarkably, the two condensates and the

external drive all rotate at different speeds due to the disparity of the

masses of the constituent bosons. In this paper we study the system by solving

the full two-component Gross-Pitaevskii equations numerically. Using this

approach we verify the stability of the putative locked state which is found to

exist within a disk centered on the axis of rotation and which depends on the

mass ratio of the two bosons. We also show that an analytic estimate of this

locking radius based on a two-body force calculation agrees well with the

numerical results.

\\ ( http://arxiv.org/abs/0909.4072 , 2369kb)

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arXiv:0909.4096

Date: Tue, 22 Sep 2009 21:08:04 GMT (162kb)

Title: Superfluid-insulator transition of disordered bosons in one-dimension

Authors: Ehud Altman, Yariv Kafri, Anatoli Polkovnikov, Gil Refael

Categories: cond-mat.dis-nn cond-mat.supr-con

Comments: 16 pages

\\

We study the superfluid-insulator transition in a one dimensional system of

interacting bosons, modeled as a disordered Josephson array, using a strong

randomness real space renormalization group technique. Unlike perturbative

methods, this approach does not suffer from run-away flows and allows us to

study the complete phase diagram. We show that the superfluid insulator

transition is always Kosterlitz- Thouless like in the way that length and time

scales diverge at the critical point. Interestingly however, we find that the

transition at strong disorder occurs at a non universal value of the Luttinger

parameter, which depends on the disorder strength. This result places the

transition in a universality class different from the weak disorder transition

first analyzed by Giamarchi and Schulz [Europhys. Lett. {\bf 3}, 1287 (1987)].

While the details of the disorder potential are unimportant at the critical

point, the type of disorder does influence the properties of the insulating

phases. We find three classes of insulators which arise for different classes

of disorder potential. For disorder only in the charging energies and Josephson

coupling constants, at integer filling we find an incompressible but gapless

Mott glass phase. If both integer and half integer filling factors are allowed

then the corresponding phase is a random singlet insulator, which has a

divergent compressibility. Finally in a generic disorder potential the

insulator is a Bose glass with a finite compressibility.

\\ ( http://arxiv.org/abs/0909.4096 , 162kb)

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arXiv:0909.4168

Date: Wed, 23 Sep 2009 10:13:28 GMT (11kb)

Title: Delayed response of a fermion-pair condensate to a modulation of the

interaction strength

Authors: J. Plata

Categories: cond-mat.quant-gas

Comments: 6 pages

Journal-ref: Europhysics Letters 87 (2009) 50001

\\

The effect of a sinusoidal modulation of the interaction strength on a

fermion-pair condensate is analytically studied. The system is described by a

generalization of the coupled fermion-boson model that incorporates a

time-dependent intermode coupling induced via a magnetic Feshbach resonance.

Nontrivial effects are shown to emerge depending on the relative magnitude of

the modulation period and the relaxation time of the condensate. Specifically,

a nonadiabatic modulation drives the system out of thermal equilibrium: the

external field induces a variation of the quasiparticle energies, and, in turn,

a disequilibrium of the associated populations. The subsequent relaxation

process is studied and an analytical description of the gap dynamics is

obtained. Recent experimental findings are explained: the delay observed in the

response to the applied field is understood as a temperature effect linked to

the condensate relaxation time.

\\ ( http://arxiv.org/abs/0909.4168 , 11kb)

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arXiv:0909.4219

Date: Wed, 23 Sep 2009 14:32:27 GMT (333kb)

Title: Effective magnetic fields for stationary light

Authors: J. Otterbach, J. Ruseckas, R. G. Unanyan, G. Juzeliunas, M.

Fleischhauer

Categories: quant-ph

\\

We describe a method to create effective gauge potentials for

stationary-light polaritons in two or three spatial dimensions. When stationary

light is created in the interaction with a uniformly rotating ensemble of

coherently driven double $\Lambda$ atoms, the equation of motion is that of a

massive Schr\"odinger particle in an effective magnetic field. In addition a

repulsive scalar potential emerges which can however be compensated by a

space-dependent detuning. Since the effective interaction area for the

polaritons can be made large, degenerate Landau levels can be created with

degeneracy well above 100. This opens the possibility to study the bosonic

analogue of the fractional quantum Hall effect for interacting stationary-light

polaritons.

\\ ( http://arxiv.org/abs/0909.4219 , 333kb)

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arXiv:0909.4406

Date: Thu, 24 Sep 2009 10:34:19 GMT (598kb)

Title: Two-channel model of photoassociation in the vicinity of a Feshbach

resonance

Authors: Philipp-Immanuel Schneider and Alejandro Saenz

Categories: cond-mat.quant-gas

Comments: 4 pages, 2 figures

\\

We derive the two-channel (TC) description of the photoassociation (PA)

process in the presence of a magnetic Feshbach resonance and compare to full

coupled multi-channel calculations for the scattering of $^{6}$Li-$^{87}$Rb.

Previously derived results [P. Pellegrini et al., Phys. Rev. Lett. 101, 053201

(2008)] are corrected. The PA process is shown to be fully described by two

parameters: the maximal transition rate and the point of vanishing transition

rate. The TC approximation reproduces excellently the PA transition rates of

the full multi-channel calculation and reveals, e.g., that the enhancement of

the rate at a resonance is directly connected to the position of vanishing

rate. For the description of two independent resonances it was found that only

three parameters completely characterize the PA process.

\\ ( http://arxiv.org/abs/0909.4406 , 598kb)

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arXiv:0909.4429

Date: Thu, 24 Sep 2009 12:38:40 GMT (2899kb,D)

Title: Phase contrast imaging of Bose condensed clouds

Authors: R. Meppelink, R. A. Rozendaal, S. B. Koller, J. M. Vogels and P. van

der Straten

Categories: cond-mat.quant-gas

Comments: 12 pages, submitted to Physical Review A

\\

Phase contrast imaging is used to observe Bose-Einstein condensates (BECs) at

finite temperature in situ. The imaging technique is used to accurately derive

the absolute phase shift of a probe laser beam due to both the condensate and

the thermal cloud. The accuracy of the method is enhanced by using the

periodicity of the intensity signal as a function of the accumulated phase. The

measured density profiles can be described using a two relevant parameter fit,

in which only the chemical potential and the temperature are to be determined.

This allows us to directly compare the measured density profiles to different

mean-field models in which the interaction between the condensed and thermal

atoms is taken into account to various degrees.

\\ ( http://arxiv.org/abs/0909.4429 , 2899kb)

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arXiv:0909.4451

Date: Thu, 24 Sep 2009 11:01:04 GMT (3414kb)

Title: Particles-vortex interactions and flow visualization in He4

Authors: Yuri A. Sergeev and Carlo F. Barenghi

Categories: cond-mat.other

Comments: To appear in the J Low Temperature Physics

\\

Recent experiments have demonstrated a remarkable progress in implementing

and use of the Particle Image Velocimetry (PIV) and particle tracking

techniques for the study of turbulence in He4. However, an interpretation of

the experimental data in the superfluid phase requires understanding how the

motion of tracer particles is affected by the two components, the viscous

normal fluid and the inviscid superfluid. Of a particular importance is the

problem of particle interactions with quantized vortex lines which may not only

strongly affect the particle motion, but, under certain conditions, may even

trap particles on quantized vortex cores. The article reviews recent

theoretical, numerical, and experimental results in this rapidly developing

area of research, putting critically together recent results, and solving

apparent inconsistencies. Also discussed is a closely related technique of

detection of quantized vortices negative ion bubbles in He4.

\\ ( http://arxiv.org/abs/0909.4451 , 3414kb)

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arXiv:0909.4506

Date: Thu, 24 Sep 2009 16:42:11 GMT (5651kb)

Title: Quantum control and measurement of atomic spins in polarization

spectroscopy

Authors: Ivan H. Deutsch, Poul S. Jessen

Categories: quant-ph

\\

Quantum control and measurement are two sides of the same coin. To affect a

dynamical map, well-designed time-dependent control fields must be applied to

the system of interest. To read out the quantum state, information about the

system must be transferred to a probe field. We study a particular example of

this dual action in the context of quantum control and measurement of atomic

spins through the light-shift interaction with an off-resonant optical probe.

By introducing an irreducible tensor decomposition, we identify the coupling of

the Stokes vector of the light field with moments of the atomic spin state.

This shows how polarization spectroscopy can be used for continuous weak

measurement of atomic observables that evolve as a function of time.

Simultaneously, the state-dependent light shift induced by the probe field can

drive nonlinear dynamics of the spin, and can be used to generate arbitrary

unitary transformations on the atoms. We revisit the derivation of the master

equation in order to give a unified description of spin dynamics in the

presence of both nonlinear dynamics and photon scattering. Based on this

formalism, we review applications to quantum control, including the design of

state-to-state mappings, and quantum-state reconstruction via continuous weak

measurement on a dynamically controlled ensemble.

\\ ( http://arxiv.org/abs/0909.4506 , 5651kb)

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arXiv:0909.4347

Date: Thu, 24 Sep 2009 02:01:44 GMT (418kb)

Title: Resonant Coupling in the Heteronuclear Alkali Dimers for Direct

Photoassociative Formation of X(0,0) Ultracold Molecules

Authors: W.C. Stwalley, J. RayMajumder, M. Bellos, R. Carollo, M. Recore, M.

Mastroianni

Categories: physics.atom-ph

Comments: 20 pages, 12 figures, Submitted to Journal of Physical Chemistry A

\\

Promising pathways for photoassociative formation of ultracold heteronuclear

alkali metal dimers in their lowest rovibronic levels (denoted X(0,0)) are

examined using high quality ab initio calculations of potential energy curves

currently available. A promising pathway for KRb, involving the resonant

coupling of the $2 ^1\Pi$ and $1 ^1\Pi $ states just below the lowest excited

asymptote (K($4s$)+Rb($5p_{1/2}$)), is found to occur also for RbCs and less

promisingly for KCs as well. The resonant coupling of the $3 ^1 \Sigma ^+ $ and

$1 ^1\Pi $ states, also just below the lowest excited asymptote, is found to be

promising for LiNa, LiK, LiRb, and less promising for LiCs and KCs. Direct

photoassociation to the $1 ^1\Pi $ state near dissociation appears promising in

the final dimers, NaK, NaRb, and NaCs, although detuning more than 100

cm$^{-1}$ below the lowest excited asymptote may be required.

\\ ( http://arxiv.org/abs/0909.4347 , 418kb)

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arXiv:0909.4448

Date: Thu, 24 Sep 2009 14:07:37 GMT (1453kb)

Title: Mimicking multi-channel scattering with single-channel approaches

Authors: Sergey Grishkevich, Philipp-Immanuel Schneider, Yulian V. Vanne and

Alejandro Saenz

Categories: physics.atom-ph physics.atm-clus

Comments: 15 pages, 10 figures

\\

The collision of two atoms is an intrinsic multi-channel (MC) problem as

becomes especially obvious in the presence of Feshbach resonances. Due to its

complexity, however, single-channel (SC) approximations, which reproduce the

long-range behavior of the open channel, are often applied in calculations. In

this work the complete MC problem is solved numerically for the magnetic

Feshbach resonances (MFRs) in collisions between generic ultracold 6Li and 87Rb

atoms in the ground state and in the presence of a static magnetic field B. The

obtained MC solutions are used to test various existing as well as presently

developed SC approaches. It was found that many aspects even at short

internuclear distances are qualitatively well reflected. This can be used to

investigate molecular processes in the presence of an external trap or in

many-body systems that can be feasibly treated only within the framework of the

SC approximation. The applicability of various SC approximations is tested for

a transition to the absolute vibrational ground state around an MFR. The

conformance of the SC approaches is explained by the two-channel approximation

for the MFR.

\\ ( http://arxiv.org/abs/0909.4448 , 1453kb)

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The replacements:

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arXiv:0803.3888

replaced with revised version Fri, 18 Sep 2009 10:05:44 GMT (54kb)

Title: The effects of next to nearest neighbor hopping on Bose-Einstein

condensation in cubic lattices

Authors: G. K. Chaudhary and R. Ramakumar

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

Comments: revised version, 10 pages with figures, intro and conclusions

modified, more results added, references added

\\ ( http://arxiv.org/abs/0803.3888 , 54kb)

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arXiv:0812.0246

replaced with revised version Fri, 18 Sep 2009 09:44:45 GMT (167kb)

Title: Bose-Einstein condensate in a quartic potential: Static and Dynamic

properties

Authors: G. K. Chaudhary, Amit K Chattopadhyay, R. Ramakumar

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

Comments: revised version, content reorganized, 15 pages including figures,

references added

\\ ( http://arxiv.org/abs/0812.0246 , 167kb)

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arXiv:0812.3403

replaced with revised version Thu, 17 Sep 2009 22:51:32 GMT (115kb)

Title: A geometrical approach to the dynamics of spinor condensates I:

Hydrodynamics

Authors: Ryan Barnett, Daniel Podolsky, Gil Refael

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

Comments: 12 pages. First paper in two-part series

Journal-ref: Phys. Rev. B 80, 024420 (2009)

\\ ( http://arxiv.org/abs/0812.3403 , 115kb)

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arXiv:0903.1863

replaced with revised version Thu, 17 Sep 2009 22:53:52 GMT (93kb)

Title: A geometrical approach to the dynamics of spinor condensates II:

Collective modes

Authors: Ryan Barnett, Daniel Podolsky, Gil Refael

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

Comments: 13 Pages. Sequel to arXiv:0812.3403

Journal-ref: Phys. Rev. B 80, 024420 (2009)

\\ ( http://arxiv.org/abs/0903.1863 , 93kb)

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arXiv:0907.0098

replaced with revised version Fri, 18 Sep 2009 10:25:35 GMT (356kb)

Title: Anderson localization of a weakly interacting one dimensional Bose gas

Authors: T. Paul, M. Albert, P. Schlagheck, P. Leboeuf, N. Pavloff

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

Comments: 20 pages, 13 figures

Journal-ref: Phys. Rev. A 80, 033615 (2009)

DOI: 10.1103/PhysRevA.80.033615

\\ ( http://arxiv.org/abs/0907.0098 , 356kb)

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arXiv:0709.2636

replaced with revised version Fri, 18 Sep 2009 08:50:01 GMT (658kb)

Title: Controlled deflection of cold atomic clouds and of Bose-Einstein

condensates

Authors: Naceur Gaaloul (PPM, LSAMA), Laurence Pruvost (LAC), Mourad Telmini

(LSAMA), Eric Charron (PPM)

Categories: quant-ph

Journal-ref: European Physical Journal D 53, 3 (2009) 343

DOI: 10.1140/epjd/e2009-00130-9

\\ ( http://arxiv.org/abs/0709.2636 , 658kb)

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arXiv:0807.4990

replaced with revised version Mon, 21 Sep 2009 02:09:58 GMT (104kb)

Title: Imbalanced superfluid state in an annular disk

Authors: Fei Ye, Yan Chen, Z. D. Wang and F. C. Zhang

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

Comments: 8 pages, 10 figures. Final version with references added and

discussion on Sarma state removed

Journal-ref: J. Phys.: Condens. Matter 21 (2009) 355701

\\ ( http://arxiv.org/abs/0807.4990 , 104kb)

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arXiv:0905.3312

replaced with revised version Mon, 21 Sep 2009 16:50:22 GMT (18kb)

Title: Correlation dynamics of strongly-correlated bosons in time-dependent

optical lattices

Authors: Karen Rodriguez, Arturo Arg\"uelles and Luis Santos

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

Comments: 4 pages, 4 figures

\\ ( http://arxiv.org/abs/0905.3312 , 18kb)

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arXiv:0906.4455

replaced with revised version Sun, 20 Sep 2009 07:55:37 GMT (65kb)

Title: Feynman path-integral treatment of the BEC-impurity polaron

Authors: J. Tempere, W. Casteels, M.K. Oberthaler, E. Timmermans, J.T. Devreese

Categories: cond-mat.quant-gas

Comments: 13 pages, 3 figures

\\ ( http://arxiv.org/abs/0906.4455 , 65kb)

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arXiv:0809.4652

replaced with revised version Tue, 22 Sep 2009 06:22:09 GMT (214kb)

Title: 7616: Critical number of ideal Bose gas confined in a cubic box

Authors: Jeong-Hyuck Park and Sang-Woo Kim

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

Comments: 1+20 pages; 3 figures (2 color and 1 B/W), title changed, major

expansion

\\ ( http://arxiv.org/abs/0809.4652 , 214kb)

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arXiv:0906.5426

replaced with revised version Tue, 22 Sep 2009 06:47:24 GMT (81kb)

Title: Effect of realistic interatomic interactions and two-body correlation on

the heat capacity of a trapped BEC

Authors: Anindya Biswas

Categories: cond-mat.quant-gas

Comments: 15 pages, 5 figures

\\ ( http://arxiv.org/abs/0906.5426 , 81kb)

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arXiv:0908.2172

replaced with revised version Tue, 22 Sep 2009 17:34:09 GMT (2065kb)

Title: Vortex structures in rotating Bose-Einstein condensates

Authors: S. I. Matveenko, D. Kovrizhin, S. Ouvry, G. V. Shlyapnikov

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

Comments: 17 pages, 12 figures, with additions

\\ ( http://arxiv.org/abs/0908.2172 , 2065kb)

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arXiv:0901.3738

replaced with revised version Tue, 22 Sep 2009 14:22:30 GMT (171kb,D)

Title: Quantum jumps and spin dynamics of interacting atoms in a strongly

coupled atom-cavity system

Authors: M. Khudaverdyan, W. Alt, T. Kampschulte, S. Reick, A. Thobe, A. Widera

and D. Meschede

Categories: quant-ph

Comments: 4 pages, 4 figures, published version

Journal-ref: Phys. Rev. Lett. 103, 123006 (2009)

DOI: 10.1103/PhysRevLett.103.123006

\\ ( http://arxiv.org/abs/0901.3738 , 171kb)

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arXiv:0908.4568

replaced with revised version Wed, 23 Sep 2009 12:35:54 GMT (587kb)

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

lattices

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

Categories: cond-mat.quant-gas

Comments: 4 pages, 4 figures; substantial changes in both text and figures

\\ ( http://arxiv.org/abs/0908.4568 , 587kb)

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arXiv:0909.3996

replaced with revised version Wed, 23 Sep 2009 03:41:37 GMT (346kb)

Title: Supersymmetric Response of Bose-Fermi Mixture to Photoassociation

Authors: T. Shi, Yue Yu, and C. P. Sun

Categories: cond-mat.other

Comments: 5 pages, 3 figures

\\ ( http://arxiv.org/abs/0909.3996 , 346kb)

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arXiv:0808.3380

replaced with revised version Tue, 22 Sep 2009 22:20:03 GMT (271kb)

Title: Space-time sensors using multiple-wave atom levitation

Authors: F. Impens and Ch. J. Bord\'e

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

Comments: 5 pages, 4 figures.Final version

Journal-ref: Phys. Rev. A 80, R031602 (2009) (Rapid. Comm.)

\\ ( http://arxiv.org/abs/0808.3380 , 271kb)

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arXiv:0906.2904

replaced with revised version Thu, 24 Sep 2009 14:54:06 GMT (1387kb)

Title: Laser Cooling by Collisional Redistribution of Radiation

Authors: Ulrich Vogl and Martin Weitz

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

Comments: 4 figures

Journal-ref: Nature 461, 70 (2009)

\\ ( http://arxiv.org/abs/0906.2904 , 1387kb)

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Till next time,

Matt.

-- ========================================================================= Dr M. J. Davis, Associate Professor in Physics School of Mathematics and Physics, ph : +61 7 334 69824 The University of Queensland, fax : +61 7 336 51242 Brisbane, QLD 4072, mdavis_at_physics.uq.edu.au Australia. www.physics.uq.edu.au/people/mdavis/ ========================================================================= Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland ========================================================================= _______________________________________________ Matts-arxiv mailing list Matts-arxiv_at_lists.sps.uq.edu.auReceived on Fri Nov 20 2009 - 18:56:28 EST

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