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

Date: Sun, 7 Oct 2007 00:55:00 +1000 (EST)

Date: Sun, 7 Oct 2007 00:55:00 +1000 (EST)

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

Hi everyone,

This week I have chosen a massive 37 new preprints, and 6 replacements. You've

been busy bees in September it seems.

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arXiv:0709.0964

Date: Thu, 6 Sep 2007 22:20:41 GMT (991kb)

Title: Computing quantum phase transitions

Authors: Thomas Vojta

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

Comments: 99 pages, 15 figures, submitted to Reviews in Computational Chemistry

\\

This article first gives a concise introduction to quantum phase transitions,

emphasizing similarities with and differences to classical thermal transitions.

After pointing out the computational challenges posed by quantum phase

transitions, a number of successful computational approaches is discussed. The

focus is on classical and quantum Monte Carlo methods, with the former being

based on the quantum-to classical mapping while the latter directly attack the

quantum problem. These methods are illustrated by several examples of quantum

phase transitions in clean and disordered systems.

\\ ( http://arxiv.org/abs/0709.0964 , 991kb)

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arXiv:0709.0985

Date: Fri, 7 Sep 2007 02:41:29 GMT (335kb,D)

Title: Matterwave Transport Without Transit

Authors: M. Rab, J. H. Cole, N. G. Parker, A. D. Greentree, L. C. L. Hollenberg

and A. M. Martin

Categories: cond-mat.other

Comments: 6 pages, 4 figures

\\

Classically it is impossible to have transport without transit, i.e., if the

points one, two and three lie sequentially along a path then an object moving

from one to three must, at some point in time, be located at two. However, for

a quantum particle in a three-well system it is possible to transport the

particle between wells one and three such that the probability of finding it at

any time in the classically accessible state in well two is negligible. We

consider theoretically the analogous scenario for a Bose-Einstein condensate

confined within a three well system. In particular, we predict the adiabatic

transportation of an interacting Bose-Einstein condensate of 2000 Li atoms from

well one to well three without transiting the allowed intermediate region. To

an observer of this macroscopic quantum effect it would appear that, over a

timescale of the order of one second, the condensate had transported, but not

transited, a macroscopic distance of 20 microns between wells one and three.

\\ ( http://arxiv.org/abs/0709.0985 , 335kb)

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arXiv:0709.1017

Date: Fri, 7 Sep 2007 08:14:25 GMT (167kb)

Title: A multibeam atom laser: coherent atom beam splitting from a single far

detuned laser

Authors: J. Dugu\'e, G. Dennis, M. Jeppesen, M. T. Johnsson, C. Figl, N. P.

Robins and J. D. Close

Categories: cond-mat.other

\\

We report the experimental realisation of a multibeam atom laser. A single

continuous atom laser is outcoupled from a Bose-Einstein condensate (BEC) via

an optical Raman transition. The atom laser is subsequently split into up to

five atomic beams with slightly different momenta, resulting in multiple,

nearly co-propagating, coherent beams which could be of use in interferometric

experiments. The splitting process itself is a novel realization of Bragg

diffraction, driven by each of the optical Raman laser beams independently.

This presents a significantly simpler implementation of an atomic beam

splitter, one of the main elements of coherent atom optics.

\\ ( http://arxiv.org/abs/0709.1017 , 167kb)

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arXiv:0709.1042

Date: Fri, 7 Sep 2007 10:33:26 GMT (570kb)

Title: Quantized vortices in atomic Bose-Einstein condensates

Authors: Kenichi Kasamatsu, Makoto Tsubota

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

Comments: 49 pages, 12 figures, review article

\\

In this review, we give an overview of the experimental and theoretical

advances in the physics of quantized vortices in dilute atomic-gas

Bose--Einstein condensates in a trapping potential, especially focusing on

experimental research activities and their theoretical interpretations. Making

good use of the atom optical technique, the experiments have revealed many

novel structural and dynamic properties of quantized vortices by directly

visualizing vortex cores from an image of the density profiles. These results

lead to a deep understanding of superfluid hydrodynamics of such systems.

Typically, vortices are stabilized by a rotating potential created by a laser

beam, magnetic field, and thermal gas. Finite size effects and inhomogeneity of

the system, originating from the confinement by the trapping potential, yield

unique vortex dynamics coupled with the collective excitations of the

condensate. Measuring the frequencies of the collective modes is an accurate

tool for clarifying the character of the vortex state. The topics included in

this review are the mechanism of vortex formation, equilibrium properties, and

dynamics of a single vortex and those of a vortex lattice in a rapidly rotating

condensate.

\\ ( http://arxiv.org/abs/0709.1042 , 570kb)

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arXiv:0709.1120

Date: Fri, 7 Sep 2007 17:09:58 GMT (16kb)

Title: Quasi-one-dimensional polarized Fermi superfluids

Authors: Meera M. Parish, Stefan K. Baur, Erich J. Mueller, David A. Huse

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

Comments: 4 pages, 2 figures

\\

We calculate the zero temperature phase diagram of a polarized two-component

Fermi gas in an array of weakly-coupled parallel one-dimensional (1D) 'tubes'

produced by a two-dimensional optical lattice. Increasing the lattice strength

drives a crossover from three-dimensional (3D) to 1D behavior, stabilizing the

Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) modulated superfluid phase. We argue

that the most promising regime for observing the FFLO phase is in the quasi-1D

regime, where the atomic motion is largely one-dimensional but there is weak

tunneling in the other directions that stabilizes long range order. In the FFLO

phase, we describe a phase transition where the quasiparticle spectrum changes

from gapless near the 3D regime to gapped in quasi-1D.

\\ ( http://arxiv.org/abs/0709.1120 , 16kb)

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arXiv:0709.1293

Date: Mon, 10 Sep 2007 01:17:15 GMT (49kb,D)

Title: Quantum corrections to the properties of an ideal Bose gas at T<T_C

Authors: E. Kovalchuk and R. Kobes

Categories: cond-mat.other

Comments: 12 pages, 13 figures, uses revtex4

\\

We consider a homogeneous equilibrium non-ideal Bose gas at nonzero

temperature below the critical temperature $T_C$ in the framework of finite

temperature field theory. Quantum corrections up to the second order are

calculated, and are shown to be important in consideration of quantities such

as the specific heat and critical exponent.

\\ ( http://arxiv.org/abs/0709.1293 , 49kb)

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arXiv:0709.1311

Date: Mon, 10 Sep 2007 05:17:09 GMT (5kb)

Title: Higher order terms in the condensate fraction of a homogeneous and

dilute Bose gas

Authors: Sang-Hoon Kim

Categories: cond-mat.stat-mech

Comments: 4 pages, 0 figure

\\

The condensate fraction of a homogeneous and dilute Bose gas is expanded as a

power series of $\sqrt{n a^3}$ as $N_0/N = 1 -c_1 (n a^3)^{1/2} -c_2 (n a^3) -

\hdots.$ The coefficient $c_1$ is well-known as $8/3 \sqrt{\pi}$, but the

others are unknown yet. We analytically obtained the coefficient $c_2$ as

$3(\pi - 8/3)$ using a double canonical transformation method.

\\ ( http://arxiv.org/abs/0709.1311 , 5kb)

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arXiv:0709.1325

Date: Mon, 10 Sep 2007 08:42:23 GMT (38kb)

Title: Dynamics of interacting particle systems: stochastic process and field

theory

Authors: Alexandre lefevre and Giulio Biroli

Categories: cond-mat.stat-mech

Comments: Article for the special issue of J Stat Mech on "Dynamics of Non

Equilibrium Systems"

Journal-ref: J. Stat. Mech. (2007) P07024

DOI: 10.1088/1742-5468/2007/07/P07024

\\

We present an approach to the dynamics of interacting particle systems, which

allows to derive path integral formulas from purely stochastic considerations.

We show that the resulting field theory is a dual version of the standard

theory of Doi and Peliti. This clarify both the origin of the Cole-Hopf map

between the two approaches and the occurence of imaginary noises in effective

Langevin equations for reaction-diffusion systems. The advantage of our

approach is that it focuses directly on the density field. We show some

applications, in particular on the Zero Range Process, hydrodynamic limits and

large deviation functional.

\\ ( http://arxiv.org/abs/0709.1325 , 38kb)

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arXiv:0709.1362

Date: Mon, 10 Sep 2007 12:06:44 GMT (162kb)

Title: Quantum-field dynamics of expanding and contracting Bose-Einstein

condensates

Authors: S. Wuester, B.J. Dabrowska-Wuester, S.M. Scott, J.D. Close and C.M.

Savage

Categories: cond-mat.other

Comments: 9 pages, 4 figures

\\

We analyze the dynamics of quantum statistics in a harmonically trapped

Bose-Einstein condensate, whose two-body interaction strength is controlled via

a Feshbach resonance. From an initially non-interacting coherent state, the

quantum field undergoes Kerr squeezing, which can be qualitatively described

with a single mode model. To render the effect experimentally accessible, we

propose a homodyne scheme, based on two hyperfine components, which converts

the quadrature squeezing into number squeezing. The scheme is numerically

demonstrated using a two-component Hartree-Fock-Bogoliubov formalism.

\\ ( http://arxiv.org/abs/0709.1362 , 162kb)

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arXiv:0709.1444

Date: Mon, 10 Sep 2007 16:38:31 GMT (64kb)

Title: Fermi-Bose transformation for the time-dependent Lieb-Liniger gas

Authors: H. Buljan, R. Pezer, T. Gasenzer

Categories: cond-mat.other

Comments: 4 pages, 1 figure

\\

An approach to calculate the exact time-evolution of a Lieb-Liniger (LL) gas

of locally interacting bosons in one spatial dimension is presented. The

many-body wave function is constructed by transforming a fully antisymmetric

(fermionic) time-dependent wave function which obeys the Schr\" odinger

equation for a free gas. This transformation employs a differential operator

which depends on the strength of the interaction and the number of particles.

The solution thus generalizes Girardeau's Fermi-Bose mapping, valid for

"impenetrable-core" bosons, to any interaction strength. The scheme is used to

exactly calculate the free expansion of a LL gas with localized initial density

distribution.

\\ ( http://arxiv.org/abs/0709.1444 , 64kb)

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arXiv:0709.1335

Date: Mon, 10 Sep 2007 09:40:43 GMT (391kb)

Title: Interference of Spontaneous Emission of Light from Two Atomic Ensembles

Authors: M. Afzelius, M. U. Staudt, H. de. Riedmatten, C. Simon, S. R.

Hastings-Simon, R. Ricken, H. Suche, W. Sohler and N. Gisin

Categories: quant-ph

Comments: submitted to New Journal of Physics

\\

We demonstrate interference of spontaneous emission of light from two distant

solid-state atomic ensembles, when both ensembles are coherently excited by a

common laser source. Owing to a strong collective enhancement of the

spontaneous emission, the atoms behave as ideal two-level quantum systems and

no which-path information is left in the atomic ensembles after emission of a

photon. This allows us to observe a high fringe visibility of 95%. Our

experiment clearly demonstrates the coherent nature of spontaneous emission.

\\ ( http://arxiv.org/abs/0709.1335 , 391kb)

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arXiv:0709.1342

Date: Mon, 10 Sep 2007 10:44:31 GMT (569kb)

Title: Electro-optic control of atom-light interactions using Rydberg

dark-state polaritons

Authors: M. G. Bason, A. K. Mohapatra, K. J. Weatherill and C. S. Adams

Categories: quant-ph

Comments: 4 pages. 5 figures

\\

We demonstrate a multiphoton Rydberg dark resonance where a Lambda-system is

coupled to a Rydberg state. This N-type level scheme combines the ability to

slow and store light pulses associated with long lived ground state

superpositions, with the strongly interacting character of Rydberg states. For

the nd_{5/2} Rydberg state in 87Rb (with n=26 or 44) and a beam size of 1 mm we

observe a resonance linewidth of less than 100 kHz in a room temperature atomic

ensemble limited by transit-time broadening. The resonance is switchable with

an electric field of order 1 V/cm. We show that, even when photons with

different wavevectors are involved, the resonance can be Doppler-free.

Applications in electro-optic switching and photonic phase gates are discussed.

\\ ( http://arxiv.org/abs/0709.1342 , 569kb)

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arXiv:0709.1352

Date: Mon, 10 Sep 2007 11:36:23 GMT (561kb)

Title: Quantum Phase Transitions of Light in the Dicke-Bose-Hubbard model

Authors: Soi-Chan Lei and Ray-Kuang Lee

Categories: quant-ph

\\

We extend the idea of quantum phase transitions of light in atom-photon

system with Dicke-Bose-Hubbard model for arbitrary number of two-level atoms.

The formulations of eigenenergies, effective Rabi frequencies, and critical

chemical potentials for two atoms are derived. With a self-consistent method,

we obtain a complete phase diagram for two two-level atoms on resonance, which

indicates the transition from Mott insulator to superfluidity and with a mean

excitations diagram for confirmation. We illustrate the generality of the

method by constructing the dressed-state basis for arbitrary number of

two-level atoms. In addition, we show that the Mott insulator lobes in the

phase diagrams will smash out with the increase of atom numbers. The results of

this work provide a step for studying the effects with combinations of

Dicke-like and Hubbard-like models to simulate strongly correlated electron

systems using photons.

\\ ( http://arxiv.org/abs/0709.1352 , 561kb)

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arXiv:0709.1424

Date: Mon, 10 Sep 2007 15:40:42 GMT (61kb)

Title: Gauss sum factorization with cold atoms

Authors: M. Gilowski, T. Wendrich, T. M\"uller, Ch. Jentsch, W. Ertmer, E. M.

Rasel, and W. P. Schleich

Categories: quant-ph

Comments: 4 pages, 5 figures

\\

We report the first implementation of a Gauss sum factorization algorithm by

an internal state Ramsey interferometer using cold atoms. A sequence of

appropriately designed light pulses interacts with an ensemble of cold rubidium

atoms. The final population in the involved atomic levels determines a Gauss

sum. With this technique we factor the number N=263193.

\\ ( http://arxiv.org/abs/0709.1424 , 61kb)

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arXiv:0709.1511

Date: Tue, 11 Sep 2007 00:15:05 GMT (564kb)

Title: Competition between attractive and repulsive interactions in

two-component Bose-Einstein condensates trapped in an optical lattice

Authors: Michal Matuszewski, Boris A. Malomed, Marek Trippenbach

Categories: cond-mat.other

\\

We consider effects of inter-species attraction on two-component gap solitons

(GSs) in the binary BEC with intra-species repulsion, trapped in the

one-dimensional optical lattice (OL). Systematic simulations of the coupled

Gross-Pitaevskii equations (GPEs) corroborate an assumption that, because the

effective mass of GSs is negative, the inter-species attraction may

\emph{split} the two-component soliton. Two critical values, $\kappa_{1} $ and

$\kappa_{2}$, of the OL strength ($\kappa $) are identified. Two-species GSs

with fully overlapping wave functions are stable in strong lattices ($\kappa

*>\kappa_{1}$). In an intermediate region, $\kappa_{1}>\kappa >\kappa_{2}$, the
*

soliton splits into a double-humped state with separated components. Finally,

in weak lattices ($\kappa <\kappa_{2}$%), the splitting generates a pair of

freely moving single-species GSs. We present and explain the dependence of

$\kappa_{1}$ and $\kappa_{2}$ on thenumber of atoms (total norm), and on the

relative strength of the competing inter-species attraction and intra-species

repulsion. The splitting of asymmetric solitons, with unequal norms of the two

species, is briefly considered too. It is found and explained that the

splitting threshold grows with the increase of the asymmetry.

\\ ( http://arxiv.org/abs/0709.1511 , 564kb)

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arXiv:0709.1542

Date: Tue, 11 Sep 2007 08:17:21 GMT (121kb)

Title: Coherent particle oscillations between two Bose-Einstein condensates

mediated by a single localized impurity atom

Authors: Uwe R. Fischer, Christian Iniotakis, Anna Posazhennikova

Categories: cond-mat.other

Comments: 4 pages of RevTex4, 4 figures

\\

We study an atomic quantum dot representing a single hyperfine ``impurity''

atom which is coherently coupled to two well-separated Bose-Einstein

condensates. It is demonstrated that the quantum dot by itself can induce

coherent oscillations of the particle imbalance between the condensates even

when the conventional tunneling between the two condensates can be completely

neglected. In the limit of noninteracting condensates, we provide an

approximate analytical solution to the coupled nonlinear equations of motion

which is in excellent agreement with the full numerical treatment.

\\ ( http://arxiv.org/abs/0709.1542 , 121kb)

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arXiv:0709.1617

Date: Tue, 11 Sep 2007 13:19:05 GMT (12kb)

Title: Frequency and damping of the Scissors Mode of a Fermi gas

Authors: G. M. Bruun and H. Smith

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

Comments: 3 pages, 2 figures

\\

We calculate the frequency and damping of the scissors mode in a classical

gas as a function of temperature and coupling strength. Our results show good

agreement with the main features observed in recent measurements of the

scissors mode in an ultracold gas of $^6$Li atoms. The comparison between

theory and experiment involves no fitting parameters and thus allows an

identification of non-classical effects at and near the unitarity limit.

\\ ( http://arxiv.org/abs/0709.1617 , 12kb)

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arXiv:0709.1669

Date: Tue, 11 Sep 2007 16:12:00 GMT (492kb)

Title: Mott transition of fermionic atoms in a three-dimensional optical trap

Authors: R. W. Helmes, T. A. Costi and A. Rosch

Categories: cond-mat.str-el

Comments: 4 pages and 5 figures

\\

We study theoretically the Mott metal-insulator transition for a system of

fermionic atoms confined in a three-dimensional optical lattice and a harmonic

trap. We describe an inhomogeneous system of several thousand sites using an

adaptation of dynamical mean field theory solved efficiently with the numerical

renormalization group method. Above a critical value of the on-site

interaction, a Mott-insulating phase appears in the system. We investigate

signatures of the Mott phase in the density profile and in time-of-flight

experiments.

\\ ( http://arxiv.org/abs/0709.1669 , 492kb)

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arXiv:0709.1690

Date: Tue, 11 Sep 2007 17:52:10 GMT (58kb)

Title: Equilibrium and dynamics of a trapped superfluid Fermi gas with unequal

masses

Authors: G. Orso, L.P. Pitaevskii and S. Stringari

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

Comments: 4 pages, 2 figures

\\

Interacting Fermi gases with equal populations but unequal masses are

investigated at zero temperature using local density approximation and the

hydrodynamic theory of superfluids in the presence of harmonic trapping.

We derive the conditions of energetic stability of the superfluid

configuration with respect to phase separation and the frequencies of the

collective oscillations in terms of the mass ratio and the trapping frequencies

of the two components. We discuss the behavior of the gas after the trapping

potential of a single component is switched off and show that, near a Feshbach

resonance, the released component can still remain trapped due to many-body

interaction effects. Explicit predictions are presented for a mixture of $^6$Li

and $^{40}$K with resonant interaction.

\\ ( http://arxiv.org/abs/0709.1690 , 58kb)

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arXiv:0709.1533

Date: Tue, 11 Sep 2007 07:04:13 GMT (331kb)

Title: Bright continuous-variable entanglement from the quantum optical dimer

Authors: M.J. Mallon, M.D. Reid and M.K. Olsen

Categories: quant-ph

Comments: 19 pages, 13 figures, theoretical

\\

We show theoretically that two evanescently coupled $\chi^{(2)}$ second

harmonic generators inside a Fabry-Perot cavity provide a tunable source of

quadrature squeezed light, Einstein-Podolsky-Rosen correlations and quantum

entanglement. Unlike systems using coupled downconverters, second harmonic

generation has no oscillation threshhold, so that the entangled fields become

macroscopically occupied as soon as the pumping fields are turned on. This

system also gives two frequencies at which the entangled fields can have

macroscopic intensity. We show how the entanglement properties can be

controlled by adjusting the pumping, the coupling strengths and the cavity

detunings.

\\ ( http://arxiv.org/abs/0709.1533 , 331kb)

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arXiv:0709.1763

Date: Wed, 12 Sep 2007 06:59:30 GMT (76kb)

Title: Trions, pairing and phase transitions in one-dimensional strongly

attractive three-component ultracold fermions

Authors: X.W. Guan, M.T. Batchelor, C. Lee and H.-Q. Zhou

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

Comments: 5 pages, 3 figures

\\

We investigate the nature of trions, pairing and quantum phase transitions in

one-dimensional three-component ultracold fermions. Exact results for the

ground state energy, phase diagrams, critical fields and magnetization are

obtained analytically from the Bethe ansatz solution. At zero temperature,

unequally spaced Zeeman splitting triggers exotic phases of trions, bound

pairs, a normal Fermi liquid and four mixtures of these states. In contrast,

for equally spaced Zeeman splitting, a critical field $H_{c1}$ is required to

break the trionic phase. A fully-polarized normal Fermi liquid occurs when the

field is greater than the upper critical value $H_{c2}$. A mixture of trions

and unpaired fermions occurs for $H_{c1}<H<H_{c2}$.

\\ ( http://arxiv.org/abs/0709.1763 , 76kb)

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arXiv:0709.1825

Date: Wed, 12 Sep 2007 12:15:52 GMT (406kb)

Title: Cold Atoms and Molecules in Self-Assembled Dipolar Lattices

Authors: G. Pupillo, A. Griessner, A. Micheli, M. Ortner, D.-W. Wang, and P.

Zoller

Categories: cond-mat.other

Comments: 4 pages, 3 figures

\\

We study the realization of lattice models, where cold atoms and molecules

move as extra particles in a dipolar crystal of trapped polar molecules. The

crystal is a self-assembled floating mesoscopic lattice structure with quantum

dynamics given by phonons. We show that within an experimentally accessible

parameter regime extended Hubbard models with tunable long-range

phonon-mediated interactions describe the effective dynamics of dressed

particles.

\\ ( http://arxiv.org/abs/0709.1825 , 406kb)

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arXiv:0709.1899

Date: Wed, 12 Sep 2007 15:32:52 GMT (58kb)

Title: Yang-Yang thermodynamics on an atom chip

Authors: A.H. van Amerongen, J.J.P. van Es, P. Wicke, K.V. Kheruntsyan, N.J.

van Druten

Categories: cond-mat.other

\\

We investigate the behavior of a weakly interacting nearly one-dimensional

(1D) trapped Bose gas at finite temperature. We perform in situ measurements of

spatial density profiles and show that they are very well described by a model

based on exact solutions obtained using the Yang-Yang thermodynamic formalism,

in a regime where other, approximate theoretical approaches fail. We

demonstrate Bose gas focusing as a means to gain experimental access to the

axial momentum distribution of the gas, and find good agreement with the in

situ results.

\\ ( http://arxiv.org/abs/0709.1899 , 58kb)

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arXiv:0709.1938

Date: Wed, 12 Sep 2007 18:18:30 GMT (294kb)

Title: Partial delocalization of two-component condensates in optical lattices

Authors: H. A. Cruz, V. A. Brazhnyi, V. V. Konotop

Categories: cond-mat.other

Comments: 8 pages, 5 figures

\\

We study management of localized modes in two-component (spinor)

Bose-Einstein condensates embedded in optical lattices by changing interspecies

interactions. By numerical integration of the coupled Gross-Pitaevskii

equations, we find three different regimes of the delocalizing transition: i)

the partial delocalization when the chemical potential of one of the components

collapses with a gap edge and the respective component transforms into a Bloch

state, while the other component remains localized; ii) the partial

delocalization as consequence of instability of one of the components; and iii)

the situation where the vector soliton reaches limits of the existence domain.

It is shown that there exists a critical value for interspecies scattering

length, below which solutions can be manipulated and above which one of the

components is irreversibly destroyed.

\\ ( http://arxiv.org/abs/0709.1938 , 294kb)

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arXiv:0709.1785

Date: Wed, 12 Sep 2007 10:05:00 GMT (504kb)

Title: Storage and Retrieval of a Squeezed Vacuum

Authors: Kazuhito Honda, Daisuke Akamatsu, Manabu Arikawa, Yoshihiko Yokoi,

Keiichirou Akiba, Satoshi Nagatsuka, Takahito Tanimura, Akira Furusawa, Mikio

Kozuma

Categories: quant-ph

\\

Quantum entanglement plays a central role for implementing quantum

information processing. Deterministic control of quantum entanglement has been

realized using a squeezed vacuum state. However, since photons are hard to

localize, coherent transfer of quantum squeezing between information carrying

photons and spatially localized atoms has long been desired. This coherent

transfer is equivalent to the storage and retrieval of quantum entanglement and

is one of the most important building blocks for implementing the intricate

tasks of quantum information processing. Here, for the first time, we

successfully demonstrate the storage and retrieval of a squeezed vacuum state

with electromagnetically induced transparency using a cold ensemble of Rb atoms

as a memory medium. These results will lead to the deterministic manipulation

of quantum fluctuations of atoms as well as the generation of highly

non-classical atomic states.

\\ ( http://arxiv.org/abs/0709.1785 , 504kb)

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arXiv:0709.1810

Date: Wed, 12 Sep 2007 11:38:49 GMT (319kb)

Title: Shaping the waveform of entangled photons

Authors: Alejandra Valencia, Alessandro Cer\`e, Xiaojuan Shi, Gabriel

Molina-Terriza, and Juan P. Torres

Categories: quant-ph

Comments: 5 Pages, 4 Figures

\\

We demonstrate experimentally the tunable control of the joint spectrum, i.e.

waveform and degree of frequency correlations, of paired photons generated in

spontaneous parametric downconversion. This control is mediated by the spatial

shape of the pump beam in a type-I noncollinear configuration. We discuss the

applicability of this technique to other sources of frequency entangled

photons, such as electromagnetically induced Raman transitions.

\\ ( http://arxiv.org/abs/0709.1810 , 319kb)

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arXiv:0709.1703 (*cross-listing*)

Date: Tue, 11 Sep 2007 19:14:08 GMT (17kb)

Title: Existence, uniqueness and approximation of stochastic Schrodinger

equation: the diffusive case

Authors: Clement Pellegrini (ICJ)

Categories: math.PR quant-ph

Proxy: ccsd hal-00171129

\\

Recent developments in quantum physics make heavy use of so-called ``quantum

trajectories''. Mathematically, this theory gives rise to ``stochastic

Schr\"odinger equations'', that is, pertubations of Schrodinger-type equations

under the form of stochastic differential equations. But such equations are in

general not of the usual type as considered in the litterature. They pose a

serious problem in terms of: justifying the existence and uniqueness of a

solution, justifying the physical pertinence of the equations. In this article

we concentrate on a particular case: the diffusive case, for a two-level

system. We prove existence and uniqueness of the associated stochastic

Schrodinger equation. We physically justify the equations by proving that they

are continuous time limit of a concrete physical procedure for obtainig quantum

trajectory.

\\ ( http://arxiv.org/abs/0709.1703 , 17kb)

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arXiv:0709.1900

Date: Wed, 12 Sep 2007 15:19:28 GMT (41kb)

Title: Quantum Chaos and Regularity in Ultracold Fermi Gases

Authors: M. Puig von Friesen, M. Ogren and S. Aberg

Categories: physics.atom-ph

Comments: 4 pages, 5 figures

\\

Quantum fluctuation of the energy is studied for an ultracold gas of

interacting fermions trapped in a three-dimensional potential. Periodic-orbit

theory is explored, and energy fluctuations are studied versus particle number

for generic regular and chaotic systems, as well for a system defined by a

harmonic confinement potential. Temperature effects on the energy fluctuations

are investigated.

\\ ( http://arxiv.org/abs/0709.1900 , 41kb)

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arXiv:0709.1906

Date: Wed, 12 Sep 2007 15:28:40 GMT (71kb)

Title: Factorization of Numbers with the temporal Talbot effect: Optical

implementation by a sequence of shaped ultrashort pulses

Authors: Damien Bigourd (LCAR), B\'eatrice Chatel (LCAR), Wolfgang P. Schleich,

Bertrand Girard (LCAR)

Categories: physics.optics

Proxy: ccsd hal-00171664

\\

We report on the successful operation of an analogue computer designed to

factor numbers. Our device relies solely on the interference of classical light

and brings together the field of ultrashort laser pulses with number theory.

Indeed, the frequency component of the electric field corresponding to a

sequence of appropriately shaped femtosecond pulses is determined by a Gauss

sum which allows us to find the factors of a number.

\\ ( http://arxiv.org/abs/0709.1906 , 71kb)

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\\

arXiv:0709.2004

Date: Thu, 13 Sep 2007 14:56:57 GMT (893kb)

Title: Bright Solitary-Matter-Wave Collisions in a Harmonic Trap: Regimes of

Soliton-like Behaviour

Authors: A. D. Martin, C. S. Adams and S. A. Gardiner

Categories: cond-mat.other

Comments: 17 pages, 10 figures

\\

Systems of solitary-waves in the 1D Gross-Pitaevskii equation, which models a

trapped atomic Bose-Einstein condensate, are investigated theoretically. To

analyse the soliton-like nature of these solitary-waves, a particle analogy for

the solitary-waves is formulated. Exact soliton solutions exist in the absence

of an external trapping potential, which behave in a particle-like manner, and

we find the particle analogy we employ to be a good model also when a harmonic

trapping potential is present. In the case of two solitons, the particle model

is integrable, and the dynamics are completely regular. The extension to three

particles supports chaotic regimes. The agreement between the particle model

and the wave dynamics remains good even in chaotic regimes. In the case of a

system of two solitary waves of equal norm, the solitons are shown to retain

their phase difference for repeated collisions. This implies that soliton-like

regimes may be found in 3D geometries where solitary waves can be made to

repeatedly collide out of phase, stabilising the condensate against collapse.

\\ ( http://arxiv.org/abs/0709.2004 , 893kb)

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\\

arXiv:0709.2094

Date: Thu, 13 Sep 2007 15:28:57 GMT (75kb,D)

Title: Quantum spin dynamics of squeezed Luttinger liquids in two-component

atomic gases

Authors: Artur Widera, Stefan Trotzky, Patrick Cheinet, Simon F\"olling,

Fabrice Gerbier, Immanuel Bloch, Vladimir Gritsev, Mikhail D. Lukin and

Eugene Demler

Categories: cond-mat.other

Comments: 4 pages, 3 figures

\\

We report on the observation of the phase dynamics of interacting

one-dimensional ultracold bosonic gases with two internal degrees of freedom.

By controlling the non-linear atomic interactions close to a Feshbach resonance

we are able to induce a phase diffusive many-body spin dynamics. We monitor

this dynamical evolution by Ramsey interferometry, supplemented by a novel,

many-body echo technique. We find that the time evolution of the system is well

described by a Luttinger liquid initially prepared in a multimode squeezed

state. Our approach allows us to probe the non-equilibrium evolution of

one-dimensional many-body quantum systems.

\\ ( http://arxiv.org/abs/0709.2094 , 75kb)

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\\

arXiv:0709.2100

Date: Thu, 13 Sep 2007 15:20:09 GMT (92kb,D)

Title: Real Time Evolution in Quantum Many-Body Systems With Unitary

Perturbation Theory

Authors: A. Hackl and S. Kehrein

Categories: cond-mat.str-el

Comments: 4 pages, 3 figures

\\

We develop a new analytical method for solving real time evolution problems

of quantum many-body systems. Our approach is a direct generalization of the

well-known canonical perturbation theory for classical systems. Similar to

canonical perturbation theory, secular terms are avoided in a systematic

expansion and one obtains stable long-time behavior. These general ideas are

illustrated by applying them to the spin-boson model and studying its

non-equilibrium spin dynamics.

\\ ( http://arxiv.org/abs/0709.2100 , 92kb)

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\\

arXiv:0709.1986

Date: Thu, 13 Sep 2007 03:50:11 GMT (18kb)

Title: Quantum walk and quantum phase transition in optical lattice

Authors: C. M. Chandrashekar and Raymond Laflamme

Categories: quant-ph

Comments: 4 pages, 5 figures

\\

We show that the quantum walk and its properties can be exploited to

redistribute the ultra-cold atoms in optical lattice into desired density

profile and quadratically speed up the the process of quantum phase transition.

We show this by evolving the density profile with every step of quantum walk by

numerical integration, where the correlation during the evolution can be

theoretically studied. We also discuss, how this can be implemented in the

realistic physical situations.

\\ ( http://arxiv.org/abs/0709.1986 , 18kb)

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\\

arXiv:0709.2011

Date: Thu, 13 Sep 2007 15:09:10 GMT (187kb)

Title: Highly non-Gaussian states created via cross-Kerr nonlinearity

Authors: Tomas Tyc and Natalia Korolkova

Categories: quant-ph

Comments: 12 pages, 7 figures

\\

We propose a feasible scheme for generation of strongly non-Gaussian states

using the cross-Kerr nonlinearity. The resultant states are highly

non-classical states of electromagnetic field and exhibit negativity of their

Wigner function, sub-Poissonian photon statistics, and amplitude squeezing.

Furthermore, the Wigner function has a distinctly pronounced ``banana'' or

``crescent'' shape specific for the Kerr-type interactions, which so far was

not demonstrated experimentally. We show that creating and detecting such

states should be possible with the present technology using electromagnetically

induced transparency in a four-level atomic system in N-configuration.

\\ ( http://arxiv.org/abs/0709.2011 , 187kb)

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\\

arXiv:0709.2095

Date: Thu, 13 Sep 2007 15:04:28 GMT (719kb)

Title: Probing quantum vacuum geometrical effects with cold atoms

Authors: Diego A. R. Dalvit, Paulo A. Maia Neto, Astrid Lambrecht, Serge

Reynaud

Categories: quant-ph

Comments: 4 pages, 3 figures

\\

The lateral Casimir-Polder force between an atom and a corrugated surface

should allow one to study experimentally non trivial geometrical effects in

quantum vacuum. Here, we derive the theoretical expression of this force in a

scattering approach that accounts for the optical properties of the corrugated

surface. We show that large corrections to the ``proximity force

approximation'' could be measured using present-day technology with a

Bose-Einstein condensate used as a vacuum field sensor.

\\ ( http://arxiv.org/abs/0709.2095 , 719kb)

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\\

arXiv:0709.2132

Date: Thu, 13 Sep 2007 17:13:33 GMT (177kb)

Title: Dynamics of vortices in weakly interacting Bose-Einstein condensates

Authors: Alexander Klein, Dieter Jaksch, Yanzhi Zhang and Weizhu Bao

Categories: quant-ph

Comments: 8 pages, 7 figures, accepted for publication in Phys. Rev. A

\\

We study the dynamics of vortices in ideal and weakly interacting

Bose-Einstein condensates using a Ritz minimization method to solve the

two-dimensional Gross-Pitaevskii equation. For different initial vortex

configurations we calculate the trajectories of the vortices. We find

conditions under which a vortex-antivortex pair annihilates and is created

again. For the case of three vortices we show that at certain times two

additional vortices may be created, which move through the condensate and

annihilate each other again. For a non-interacting condensate this process is

periodic, whereas for small interactions the essential features persist, but

the periodicity is lost. The results are compared to exact numerical solutions

of the Gross-Pitaevskii equation confirming our analytical findings.

\\ ( http://arxiv.org/abs/0709.2132 , 177kb)

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\\

arXiv:0709.2143

Date: Thu, 13 Sep 2007 18:42:21 GMT (127kb)

Title: Optimized Double-well quantum interferometry with Gaussian

squeezed-states

Authors: Y. P. Huang and M. G. Moore

Categories: quant-ph

\\

A Mach-Zehnder interferometer with a Gaussian number-squeezed input state can

exhibit beyond standard-quantum-limit (SQL) phase resolution over a large range

of measured phase-shifts in $(-\pi/2,\pi/2)$. For a single measurement, the

smallest achievable phase uncertainty is $1.63 \tan^{1/3}|\theta|/N^{2/3}$ for

nonzero phase $\theta$. Due to the explicit $\theta$ dependence, the

uncertainty converges quickly to Heisenberg scaling $\sim 1/N$ with only a few

additional adaptive measurements. In contrast, previously studied input states

degrade to worse than SQL for nonzero phases, and are not amenable to multiple

adaptive measurement schemes. Our optimized scheme can be readily implemented

in a double-well Bose-Einstein condensate system.

\\ ( http://arxiv.org/abs/0709.2143 , 127kb)

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The replacements:

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\\

arXiv:cond-mat/0703322

replaced with revised version Mon, 10 Sep 2007 12:53:29 GMT (355kb)

Title: Heteronuclear molecules in an optical lattice: Theory and experiment

Authors: Frank Deuretzbacher, Kim Plassmeier, Daniela Pfannkuche, F\'elix

Werner, Christian Ospelkaus, Silke Ospelkaus, Klaus Sengstock, Kai Bongs

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

Comments: 10 pages, 7 figures

\\ ( http://arxiv.org/abs/cond-mat/0703322 , 355kb)

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\\

arXiv:0707.2625

replaced with revised version Mon, 10 Sep 2007 09:00:27 GMT (33kb)

Title: Radio Frequency Spectroscopy of Trapped Fermi Gases with Population

Imbalance

Authors: Yan He, Chih-Chun Chien, Qijin Chen, and K. Levin

Categories: cond-mat.str-el cond-mat.supr-con

Comments: 4 page, 3 figures, submitted to PRA Rapid

\\ ( http://arxiv.org/abs/0707.2625 , 33kb)

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\\

arXiv:0706.1840

replaced with revised version Tue, 11 Sep 2007 09:06:09 GMT (301kb)

Title: Vortex pump for dilute Bose-Einstein condensates

Authors: Mikko Mottonen, Ville Pietila, Sami M. M. Virtanen

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

Comments: 4 pages, 3 figures

\\ ( http://arxiv.org/abs/0706.1840 , 301kb)

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\\

arXiv:0709.0362

replaced with revised version Tue, 11 Sep 2007 07:12:49 GMT (230kb)

Title: Non-perturbative renormalization-group approach to zero-temperature Bose

systems

Authors: N. Dupuis and K. Sengupta

Categories: cond-mat.other hep-th

Comments: v1) 6 pages, 8 figures; v2) added references

\\ ( http://arxiv.org/abs/0709.0362 , 230kb)

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\\

arXiv:0705.1634 (*cross-listing*)

replaced with revised version Wed, 12 Sep 2007 15:17:53 GMT (142kb)

Title: Relativistic BCS-BEC Crossover at Finite Temperature and Its Application

to Color Superconductivity

Authors: Lianyi He and Pengfei Zhuang

Categories: hep-ph astro-ph cond-mat.supr-con nucl-th

Comments: 13 pages, 7 figures. V2: comparision with other theories and new

results on color superconductivity are added. V3: version published in PRD

Journal-ref: Phys. Rev. D 76, 056003 (2007)

DOI: 10.1103/PhysRevD.76.056003

\\ ( http://arxiv.org/abs/0705.1634 , 142kb)

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\\

arXiv:0707.0383

replaced with revised version Wed, 12 Sep 2007 16:52:14 GMT (208kb)

Title: Pair condensation of bosonic atoms induced by optical lattices

Authors: Maria Eckholt, Juan Jose Garcia-Ripoll

Categories: cond-mat.other quant-ph

Comments: Improved readability

Report-no: NSF-KITP-07-155

\\ ( http://arxiv.org/abs/0707.0383 , 208kb)

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Till next time,

Matt.

-- ========================================================================= Dr M. J. Davis, Senior Lecturer in Physics School of Physical Sciences, email: mdavis_at_physics.uq.edu.au University of Queensland, ph : +61 7 334 69824 Brisbane, QLD 4072, fax : +61 7 336 51242 Australia. http://www.physics.uq.edu.au/people/mdavis/ ========================================================================= Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland =========================================================================Received on Sun Oct 07 2007 - 00:55:00 EST

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