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

Date: Mon, 6 Nov 2006 17:43:52 +1000 (EST)

Date: Mon, 6 Nov 2006 17:43:52 +1000 (EST)

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

Home page: http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/

A total of 28 new abstracts this week:

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Paper: cond-mat/0610749

Date: Thu, 26 Oct 2006 20:03:27 GMT (218kb)

Title: Dynamical collapse in a degenerate binary fermion mixture using a

hydrodynamic model

Authors: Sadhan K. Adhikari

Comments: 18 pages, 9 figures

Subj-class: Other

Journal-ref: New J. Phys 8 (2006) 258 (1-15)

\\

We use a time-dependent dynamical hydrodynamic model to study a collapse in a

degenerate fermion-fermion mixture (DFFM) of different atoms. Due to a strong

Pauli-blocking repulsion among identical spin-polarized fermions at short

distances there cannot be a collapse for repulsive interspecies fermion-fermion

interaction. However, there can be a collapse for a sufficiently attractive

interspecies fermion-fermion interaction in a DFFM of different atoms. Using a

variational analysis and numerical solution of the hydrodynamic model we study

different aspects of collapse in such a DFFM initiated by a jump in the

interspecies fermion-fermion interaction (scattering length) to a large

negative (attractive) value using a Feshbach resonance. Suggestion for

experiments of collapse in a DFFM of distinct atoms is made.

\\ ( http://arXiv.org/abs/cond-mat/0610749 , 218kb)

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Paper: cond-mat/0610766

Date: Fri, 27 Oct 2006 11:25:02 GMT (130kb)

Title: Cold Collision Frequency Shift in Two-Dimensional Atomic Hydrogen

Authors: J. Ahokas, J. Jarvinen, and S. Vasiliev

Comments: 4 pages, 3 figures

Subj-class: Other

\\

We report a measurement of the cold collision frequency shift in atomic

hydrogen gas adsorbed on the surface of superfluid 4He at T<=90 mK. Using

two-photon electron and nuclear magnetic resonance in 4.6 T field we separate

the resonance line shifts due to the dipolar and exchange interactions, both

proportional to surface density sigma. We find the clock shift Delta v_c =

-1.0(1)x10^-7 Hz cm^-2 x sigma, which is about 100 times smaller than the value

predicted by the mean field theory and known scattering lengths in the 3D case.

\\ ( http://arXiv.org/abs/cond-mat/0610766 , 130kb)

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Paper: cond-mat/0610767

Date: Fri, 27 Oct 2006 14:42:46 GMT (910kb)

Title: Universality in nonadiabatic behaviour of classical actions in nonlinear

models with separatrix crossings

Authors: A.P. Itin, S. Watanabe

Comments: 17 pages, 11 figures

Subj-class: Other

\\

We discuss dynamics of approximate adiabatic invariants in several nonlinear

models being related to physics of Bose-Einstein condensates (BEC). We show

that nonadiabatic dynamics in Feschbach resonance passage, nonlinear

Landau-Zener (NLZ) tunnelling, and BEC tunnelling oscillations in a double-well

can be considered within a unifying approach based on the theory of separatrix

crossings. The problems were considered previously within nonlinear two-state

models, and there are regimes of motion that was not discussed so far in the

context of nonadiabatic behaviour, that is when initial populations of either

mode of a two-mode system are not zero or very small. Here we consider a

two-mode model for coupled atom-molecular BEC, and a two-mode model for two

coupled (atomic) BECs as examples. The former model is able to describe process

of Feschbach resonance passage, while the latter is similar to NLZ model.

Self-trapping phenomenon and the associated \emph{geometric} jump in action can

lead to nonzero adiabatic tunnelling in NLZ models and non-zero remnant

population at adiabatic Feschbach resonance crossing. However, the most

complicated issue is \emph{dynamical} jumps in action at separatrix crossings

which were investigated previously in some problems of classical mechanics,

plasma physics and hydrodynamics, but have not got adequate treatment in

BEC-related models yet. We derive explicit formulas for the change in the

action in several models using a general method of classical adiabatic theory.

Extensive numerical calculations support the general theory and demonstrate its

universal character. We also discovered a qualitatively new nonlinear

phenomenon in a NLZ model which we propose to call {\em separated adiabatic

tunnelling}.

\\ ( http://arXiv.org/abs/cond-mat/0610767 , 910kb)

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Paper: cond-mat/0610773

Date: Fri, 27 Oct 2006 14:00:42 GMT (547kb)

Title: Dynamical properties of ultra-cold bosons in an optical lattice

Authors: S.D. Huber, E. Altman, H.P. B\"uchler, and G. Blatter

Comments: 13 pages, 5 figures

Subj-class: Other

\\

We study the excitation spectrum of strongly correlated lattice bosons for

the Mott-insulating phase and for the superfluid phase close to localization.

Within a Schwinger-boson mean-field approach we find two gapped modes in the

Mott insulator and the combination of a sound mode (Goldstone) and a gapped

(Higgs) mode in the superfluid. To make our findings comparable with

experimental results, we calculate the dynamic structure factor as well as the

linear response to the optical lattice modulation introduced by Stoeferle et

al. [Phys. Rev. Lett. 92, 130403 (2004)]. We find that the puzzling finite

frequency absorption observed in the superfluid phase could be explained via

the excitation of the gapped (Higgs) mode. We check the consistency of our

results with an adapted f-sum-rule and propose an extension of the experimental

technique by Stoeferle et al. to further verify our findings.

\\ ( http://arXiv.org/abs/cond-mat/0610773 , 547kb)

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Paper (*cross-listing*): nucl-th/0610105

Date: Thu, 26 Oct 2006 13:46:12 GMT (32kb)

Title: Universal Properties of the Four-Body System with Large Scattering

Length

Authors: H.-W. Hammer (Bonn U.), L. Platter (Ohio U.)

Comments: 14 pages, 4 ps figures

Report-no: HISKP-TH-06/31

Subj-class: Nuclear Theory; Other

\\

Few-body systems with large scattering length have universal properties that

do not depend on the details of their interactions at short distances. We study

the universal bound state properties of the four-boson system with large

scattering length in an effective quantum mechanics approach. We compute the

four-body binding energies using the Yakubovsky equations for positive and

negative scattering length. Moreover, we study the correlation between three-

and four-body energies and present a generalized Efimov plot for the four-body

system. These results are useful for understanding the cluster structure of

nuclei and for the creation of weakly-bound tetramers with cold atoms close to

a Feshbach resonance.

\\ ( http://arXiv.org/abs/nucl-th/0610105 , 32kb)

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Paper: physics/0610253

Date: Fri, 27 Oct 2006 12:02:14 GMT (233kb)

Title: All-optical atomic magnetometers based on nonlinear magneto-optical

rotation with amplitude modulated light

Authors: S. Pustelny, A. Wojciechowski, M. Kotyrba, K. Sycza, J. Zachorowski,

W. Gawlik, A. Cingoz, N. Leefer, J. M. Higbie, E. Corsinib, M. P. Ledbetter,

S. M. Rochester, A. O. Sushkov, and D. Budker

Comments: 8 pages, 6 figures, Submitted to Proc. of SPIE, Proceedings of XIVth

International School on Quantum Electronics, Sunny Beach, Bulgaria 2006

Subj-class: Atomic Physics; Optics

\\

We demonstrate a magnetometric technique based on nonlinear magneto-optical

rotation using amplitude modulated light. The magnetometers can be operated in

either open-loop (typical nonlinear magneto-optical rotation with

amplitude-modulated light) or closed-loop (self-oscillating) modes. The latter

mode is particularly well suited for conditions where the magnetic field is

changing by large amounts over a relatively short timescale.

\\ ( http://arXiv.org/abs/physics/0610253 , 233kb)

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Paper: cond-mat/0610797

Date: Sat, 28 Oct 2006 18:49:26 GMT (50kb)

Title: Theory of Critical Temperature Adiabatic Change for Ideal Gas

Bose-Einstein Condensation in Optical Lattices

Authors: G.A. Muradyan and A.Zh. Muradyan

Subj-class: Other; Statistical Mechanics

\\

We present a scheme of analytical calculations determining the critical

temperature and the number of condensed atoms of ideal gas Bose-Einstein

condensation in external potentials with 1D, 2D or 3D periodicity. In

particular we show that the width of the lowest energy band appears as the main

parameter determining the critical temperature of condensation. Is obtained a

very simple, proportional to 1/3 degree, regularity for this dependence. The

fundamental role of tunneling in physics of condensate establishment is

underscored.

\\ ( http://arXiv.org/abs/cond-mat/0610797 , 50kb)

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Paper: cond-mat/0610798

Date: Sat, 28 Oct 2006 19:00:47 GMT (278kb)

Title: Large-N expansion for unitary superfluid Fermi gases

Authors: M. Y. Veillette, D. E. Sheehy, and L. Radzihovsky

Comments: 13 pages

Subj-class: Other

\\

We analyze strongly interacting Fermi gases in the unitary regime by

considering the generalization to an arbitrary number N of spin-1/2 fermion

flavors with Sp(2N) symmetry. For N=\infty this problem is exactly solved by

the BCS-BEC mean-field theory, with corrections small in the parameter 1/N. The

large-N expansion provides a systematic way to determine corrections to

mean-field predictions, allowing the calculation of a variety of thermodynamic

quantities at (and in the proximity to) unitarity, including the energy, the

pairing gap, and upper-critical polarization (in the case of a polarized gas)

for the normal to superfluid instability. For the physical case of N=1, among

other quantities, we predict in the unitarity regime, the energy of the gas to

be \xi=0.28 times that for the non-interacting gas and the pairing gap to be

0.52 times the Fermi energy.

\\ ( http://arXiv.org/abs/cond-mat/0610798 , 278kb)

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Paper: cond-mat/0610804

Date: Sun, 29 Oct 2006 08:26:12 GMT (34kb)

Title: Intensity correlations and mesoscopic fluctuations of diffusing photons

in cold atoms

Authors: O. Assaf and E. Akkermans

Comments: 4 pages, 2 figures

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\

We study the angular correlation function of speckle patterns that result

from multiple scattering of photons by cold atomic clouds. We show that this

correlation function becomes larger than the value given by Rayleigh law for

classical scatterers. These large intensity fluctuations constitute a new

mesoscopic interference effect specific to atom-photon interactions, that could

not be observed in other systems such as weakly disordered metals. We provide a

complete description of this behavior and expressions that allow for a

quantitative comparison with experiments.

\\ ( http://arXiv.org/abs/cond-mat/0610804 , 34kb)

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Paper: cond-mat/0610830

Date: Mon, 30 Oct 2006 12:19:19 GMT (16kb)

Title: Superfluidity of a Bose gas in the presence of a random potential

Authors: M. Ogren, G. M. Kavoulakis (LTH, Lund)

Comments: 4 pages, RevTex, 3 figures

Subj-class: Other

\\

We examine bosonic atoms that are confined in a toroidal,

quasi-one-dimensional trap, subjected to a random potential. The resulting

inhomogeneous atomic density is smoothened for sufficiently strong, repulsive

interatomic interactions. The gas supports persistent currents, which become

more fragile due to the disorder. Strong disorder requires correspondingly

strong interactions in order for the currents to be (meta)stable.

\\ ( http://arXiv.org/abs/cond-mat/0610830 , 16kb)

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Paper: cond-mat/0610844

Date: Mon, 30 Oct 2006 20:30:41 GMT (87kb)

Title: A Cold Atomic Fermi Gas with a Spatially Modulated Interaction

Authors: Hao Fu, Alberto G. Rojo

Comments: 10 pages, 3 figures

Subj-class: Superconductivity; Other

\\

We study an ultra-cold atomic Fermi Gas with the atom-atom interaction

modulated periodically in space. A novel ground state with cooper pairs

occupying non-zero center of mass momenta is found. Such a state is closely

related to the state proposed by Fulde, Ferrell, Larkin, and Ovchinnikov(FFLO).

The resultant single particle excitations with momenta along the direction of

the modulation shows multiple-gap structures. Such a system can be realized in

experiment with a spatially modulated Feshbach resonance. Experimental

signatures of such a state are discussed.

\\ ( http://arXiv.org/abs/cond-mat/0610844 , 46kb)

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Paper: cond-mat/0610848

Date: Mon, 30 Oct 2006 18:47:34 GMT (63kb)

Title: Renormalized mean-field theory for a two-component Fermi gas with s-wave

interactions

Authors: Javier von Stecher, Chris H. Greene

Comments: 11 pages, 9 figures, 2 tables

Subj-class: Superconductivity

\\

A method is introduced to renormalize the zero-range interaction for use in

mean-field and many-body theory, starting from two-body calculations. The

density-renormalized delta-function interaction is then applied using

mean-field theory to a two-component fermion gas, and compared with diffusion

Monte Carlo simulations and conventional mean-field calculations. In the

unitarity limit, the equation of state exhibits the expected behavior

$\mu\propto\rho^{2/3}$, with a parameter $\beta= -0.492$, which is consistent

with recent experiments \cite{partridge2006pap, bourdel2004esb, kinast2005hcs,

Stewart06}.

\\ ( http://arXiv.org/abs/cond-mat/0610848 , 63kb)

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Paper: quant-ph/0610244

Date: Mon, 30 Oct 2006 07:28:01 GMT (519kb)

Title: Emergent quantum phases in a heteronuclear molecular Bose--Einstein

condensate model

Authors: Melissa Duncan, Angela Foerster, Jon Links, Eduardo Mattei, Norman

Oelkers, Arlei Prestes Tonel

Comments: 23 pages, 10 figures

\\

We study a three-mode Hamiltonian modelling a heteronuclear molecular

Bose--Einstein condensate. Two modes are associated with two distinguishable

atomic constituents, which can combine to form a molecule represented by the

third mode. Beginning with a semi-classical analogue of the model, we conduct

an analysis to determine the phase space fixed points of the system.

Bifurcations of the fixed points naturally separate the coupling parameter

space into different regions. Two distinct scenarios are found, dependent on

whether the imbalance between the number operators for the atomic modes is zero

or non-zero. This result suggests the ground-state properties of the model

exhibit an unusual sensitivity on the atomic imbalance. We then test this

finding for the quantum mechanical model. Specifically we use Bethe ansatz

methods, ground-state expectation values, the character of the quantum

dynamics, and ground-state wavefunction overlaps to clarify the nature of the

ground-state phases. The character of the transition is smoothed due to quantum

fluctuations, but we may nonetheless identify the emergence of a quantum phase

boundary in the limit of zero atomic imbalance.

\\ ( http://arXiv.org/abs/quant-ph/0610244 , 519kb)

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Paper: quant-ph/0610251

Date: Mon, 30 Oct 2006 15:15:36 GMT (3kb)

Title: Reply to Comment on 'Spin Decoherence in Superconducting Atom Chips'

Authors: Bo-Sture K. Skagerstam, Ulrich Hohenester, Asier Eiguren, and Per

Kristian Rekdal

Comments: 1 page

\\

This is a reply to the Comment on 'Spin Decoherence in Superconducting Atom

Chips' [arXiv:quant-ph/0610095 (2006)].

\\ ( http://arXiv.org/abs/quant-ph/0610251 , 3kb)

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Paper: physics/0610261

Date: Sat, 28 Oct 2006 12:17:41 GMT (29kb)

Title: Low-energy three-body dynamics in binary quantum gases

Authors: O. I. Kartavtsev, A. V. Malykh

Comments: 16 pages

Subj-class: Atomic Physics

\\

The universal three-body dynamics in ultra-cold binary Fermi and Fermi-Bose

mixtures is studied. Two identical fermions of the mass $m$ and a particle of

the mass $m_1$ with the zero-range two-body interaction in the states of the

total angular momentum L=1 are considered. Using the boundary condition model

for the s-wave interaction of different particles, both eigenvalue and

scattering problems are treated by solving hyper-radial equations, whose terms

are derived analytically. The dependencies of the three-body binding energies

on the mass ratio $m/m_1$ for the positive two-body scattering length are

calculated; it is shown that the ground and excited states arise at $m/m_1 \ge

\lambda_1 \approx 8.17260$ and $m/m_1 \ge \lambda_2 \approx 12.91743$,

respectively. For $m/m_1 \alt \lambda_1$ and $m/m_1 \alt \lambda_2$, the

relevant bound states turn to narrow resonances, whose positions and widths are

calculated. The 2 + 1 elastic scattering and the three-body recombination near

the three-body threshold are studied and it is shown that a two-hump structure

in the mass-ratio dependencies of the cross sections is connected with arising

of the bound states.

\\ ( http://arXiv.org/abs/physics/0610261 , 29kb)

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Paper: cond-mat/0610862

Date: Tue, 31 Oct 2006 07:57:30 GMT (546kb)

Title: Topological defect formation in quenched ferromagnetic Bose-Einstein

condensates

Authors: Hiroki Saito, Yuki Kawaguchi, and Masahito Ueda

Comments: 10 pages, 11 figures

Subj-class: Other

\\

We study the dynamics of the quantum phase transition of a ferromagnetic

spin-1 Bose-Einstein condensate from the polar phase to the broken-axisymmetry

phase by changing magnetic field, and find the spontaneous formation of spinor

domain walls followed by the creation of polar-core spin vortices. We also find

that the spin textures depend very sensitively on the initial noise

distribution, and that an anisotropic and colored initial noise is needed to

reproduce the Berkeley experiment [Sadler et al., Nature 443, 312 (2006)]. The

dynamics of vortex nucleation and the number of created vortices depend also on

the manner in which the magnetic field is changed. We point out an analogy

between the formation of spin vortices from domain walls in a spinor BEC and

that of vortex-antivortex pairs from dark solitons in a scalar BEC.

\\ ( http://arXiv.org/abs/cond-mat/0610862 , 546kb)

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Paper: cond-mat/0610881

Date: Tue, 31 Oct 2006 13:59:21 GMT (186kb)

Title: Dark solitons in external potentials

Authors: Dmitry E. Pelinovsky and Panayotis G. Kevrekidis

Comments: 39 pages, 10 figures

Subj-class: Other

\\

We consider the persistence and stability of dark solitons in the

Gross-Pitaevskii (GP) equation with a small decaying potential. We show that

families of black solitons with zero speed originate from extremal points of an

appropriately defined effective potential and persist for sufficiently small

strength of the potential. We prove that families at the maximum points are

generally unstable with exactly one real positive eigenvalue, while families at

the minimum points are generally unstable with exactly two complex-conjugated

eigenvalues with positive real part. This mechanism of destabilization of the

black soliton is confirmed in numerical approximations of eigenvalues of the

linearized GP equation and full numerical simulations of the nonlinear GP

equation with cubic nonlinearity. We illustrate the monotonic instability

associated with the real eigenvalues and the oscillatory instability associated

with the complex eigenvalues and compare the numerical results of evolution of

a dark soliton with the predictions of Newton's particle law for its position.

\\ ( http://arXiv.org/abs/cond-mat/0610881 , 186kb)

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Paper: cond-mat/0611010

Date: Wed, 1 Nov 2006 09:53:06 GMT (15kb)

Title: Mixtures of fermionic atoms in an optical lattice

Authors: K. Ziegler

Subj-class: Disordered Systems and Neural Networks; Statistical Mechanics

\\

A mixture of light and heavy spin-polarized fermionic atoms in an optical

lattice is considered. Tunneling of the heavy atoms is neglected such that they

are only subject to thermal fluctuations. This results in a complex interplay

between light and heavy atoms caused by quantum tunneling of the light atoms.

The distribution of the heavy atoms is studied. It can be described by an

Ising-like distribution with a first-order transition from homogeneous to

staggered order. The latter is caused by an effective nonlocal interaction due

to quantum tunneling of the light atoms. A second-order transition is also

possible between an ordered and a disordered phase of the heavy atoms.

\\ ( http://arXiv.org/abs/cond-mat/0611010 , 15kb)

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Paper: cond-mat/0611017

Date: Wed, 1 Nov 2006 16:18:19 GMT (51kb)

Title: Quantum quenches in a spinor condensate

Authors: Austen Lamacraft

Subj-class: Statistical Mechanics

\\

We discuss the ordering of a spin-1 condensate when quenched from its

paramagnetic phase to its ferromagnetic phase by reducing magnetic field. We

first elucidate the nature of the equilibrium quantum phase transition, which

has a multicritical point when the magnetization in the direction of the field

vanishes. Quenching through this transition reveals XY ordering either at a

specific wavevector, or the `light-cone' correlations familiar from

relativistic theories, depending on the endpoint of the quench. The creation of

vortices through growth of the magnetization fluctuations is also discussed.

The long time dynamics again depends on the endpoint, conserving the order

parameter in zero field, but not at finite field, with differing exponents for

the coarsening of magnetic order. The results are discussed in the light of a

recent experiment by Sadler et al.

\\ ( http://arXiv.org/abs/cond-mat/0611017 , 51kb)

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Paper: cond-mat/0611022

Date: Wed, 1 Nov 2006 20:56:55 GMT (427kb)

Title: Resonantly-paired fermionic superfluids

Authors: V. Gurarie, L. Radzihovsky

Comments: 71 pgs, 28 eps figures

Subj-class: Superconductivity

\\

We present a theory of a degenerate atomic Fermi gas, interacting through a

narrow Feshbach resonance, whose position and therefore strength can be tuned

experimentally, as demonstrated recently in ultracold trapped atomic gases. The

distinguishing feature of the theory is that its accuracy is controlled by a

dimensionless parameter proportional to the ratio of the width of the resonance

to Fermi energy. The theory is therefore quantitatively accurate for a narrow

Feshbach resonance. In the case of a narrow s-wave resonance, our analysis

leads to a quantitative description of the crossover between a weakly-paired

BCS superconductor of overlapping Cooper pairs and a strongly-paired molecular

Bose-Einstein condensate of diatomic molecules. In the case of pairing via a

p-wave resonance, that we show is always narrow for a sufficiently low density,

we predict a detuning-temperature phase diagram, that in the course of a

BCS-BEC crossover can exhibit a host of thermodynamically-distinct phases

separated by quantum and classical phase transitions. For an intermediate

strength of the dipolar anisotropy, the system exhibits a p_x + i p_y paired

superfluidity that undergoes a topological phase transition between a

weakly-coupled gapless ground state at large positive detuning and a

strongly-paired fully-gapped molecular superfluid for a negative detuning. In

two dimensions the former state is characterized by a Pfaffian ground state

exhibiting topological order and non-Abelian vortex excitations familiar from

fractional quantum Hall systems.

\\ ( http://arXiv.org/abs/cond-mat/0611022 , 427kb)

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Paper: quant-ph/0611005

Date: Tue, 31 Oct 2006 23:21:06 GMT (500kb)

Title: Quantum correlation in the photoassociation of a heteronuclear molecular

Bose-Einstein Condensate

Authors: Lu Zhou, Weiping Zhang, Hong Y. Ling, Han Pu

Comments: 9 pages, 11 figures

\\

We study a atomic-molecular model for interspecies photoassociation. A

general Hamiltonian which takes into account the s-wave scattering interactions

are considered. By approximating the quantum Hamiltonian by a classical

Hamiltonian, the fixed points of the system are found. The stability analysis

is performed and we found that the population imbalance between the two atomic

species will play an important role in the modulational instability of the

system. It is found that effecient photoassociation could be achieved in wider

experimental parameter region with population imbalance. The dynamics of the

system is predicted with mean-field theory as well as with quantum solution.

The difference between them are found and analyzed. In addition, we give a

brief discussion on the role of the quantum statistical properties of the

initial atomic condensate state on the dynamics of the system. The time

evolution of the correlation between atoms of different species are calculated

with different initial states and we found that the two species can be kept

anti-correlated under appropriate conditions. We also numerically show that

quantum statistical properties of the matter wave field changes due to the

nonlinear interaction.

\\ ( http://arXiv.org/abs/quant-ph/0611005 , 500kb)

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Paper: physics/0611003

Date: Wed, 1 Nov 2006 01:04:59 GMT (109kb)

Title: Probing Ultracold Collisional Dynamics with Frequency-Chirped Pulses

Authors: M.J. Wright, J.A. Pechkis, J.L. Carini, and P.L. Gould

Comments: Accepted by PRA

Subj-class: Atomic Physics

\\

We report on the dynamics of ultracold collisions induced by near-resonant

frequency-chirped light. A series of identical chirped pulses, separated by a

variable delay, is applied to an ultracold sample of 85Rb, and the rate of

inelastic trap-loss collisions is measured. For small detunings of the chirped

light below the atomic resonance, we observe that the rate of collisions

induced by a given pulse can be increased by the presence of an earlier pulse.

We attribute this to the enhancement of short-range collisional flux by the

long-range excitation of atom pairs to an attractive molecular potential. For

larger detunings and short delays, we find that a leading pulse can suppress

the rate of collisions caused by a following pulse. This is due to a depletion

of short-range atom pairs by the earlier pulse. Comparison of our data to

classical Monte-Carlo simulations of the collisions yields reasonable

agreement.

\\ ( http://arXiv.org/abs/physics/0611003 , 109kb)

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Paper: cond-mat/0611028

Date: Wed, 1 Nov 2006 19:48:32 GMT (166kb)

Title: Modification of scattering lengths via magnetic dipole-dipole

interactions

Authors: I.E. Mazets and G. Kurizki

Comments: revtex, 4 pages, 3 figures

Subj-class: Statistical Mechanics; Atomic Physics

\\

We propose a new mechanism for tuning an atomic s-wave scattering length. The

effect is caused by virtual transitions between different Zeeman sublevels via

magnetic dipole-dipole interactions. These transitions give rise to an

effective potential, which, in contrast to standard magnetic interactions, has

an isotropic component and thus affects s-wave collisions. Our numerical

analysis shows that for chromium-50 the scattering length can be modified up to

15 %.

\\ ( http://arXiv.org/abs/cond-mat/0611028 , 166kb)

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Paper: cond-mat/0611043

Date: Thu, 2 Nov 2006 07:40:48 GMT (111kb)

Title: Bose-Einstein condensates and quantum non-locality

Authors: Franck Lalo\"{e} (LKB - Lhomond)

Comments: contribution to the workshop "Beyond que quantum", at the Lorentz

Institute (Leiden, Netherlands) in may 2006

Proxy: ccsd hal-00110808

Subj-class: Other

\\

The EPR argument points to the existence of additional variables that are

necessary to complete standard quantum theory. It was dismissed by Bohr because

it attributes physical reality to isolated microscopic systems, independently

of the macroscopic measurement apparatus. Here, we transpose the EPR argument

to macroscopic systems, assuming that they are in spatially extended Fock spin

states and subject to spin measurements in remote regions of space. Bohr's

refutation of the EPR argument does not seem to apply in this case, since the

difference of scale between the microscopic measured system and the macroscopic

measuring apparatus can no longer be invoked.

\\ ( http://arXiv.org/abs/cond-mat/0611043 , 111kb)

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Paper: cond-mat/0611047

Date: Thu, 2 Nov 2006 09:32:27 GMT (33kb)

Title: Collisional decay of 87Rb Feshbach molecules at 1005.8 G

Authors: N. Syassen, T. Volz, S. Teichmann, S. D\"urr, G. Rempe

Subj-class: Statistical Mechanics

\\

We present measurements of the loss-rate coefficients K_am and K_mm caused by

inelastic atom-molecule and molecule-molecule collisions. A thermal cloud of

atomic 87Rb is prepared in an optical dipole trap. A magnetic field is ramped

across the Feshbach resonance at 1007.4 G. This associates atom pairs to

molecules. A measurement of the molecule loss at 1005.8 G yields K_am=2 10^-10

cm^3/s. Additionally, the atoms can be removed with blast light. In this case,

the measured molecule loss yields K_mm=3 10^-10 cm^3/s.

\\ ( http://arXiv.org/abs/cond-mat/0611047 , 33kb)

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Paper: cond-mat/0611054

Date: Thu, 2 Nov 2006 18:12:27 GMT (439kb)

Title: Formation of molecules and entangled atomic pairs from atomic BEC due to

Feshbach resonance

Authors: Vladimir A. Yurovsky (Tel Aviv University)

Comments: 34 pages, 15 figures

Subj-class: Soft Condensed Matter

\\

Bose-Einstein condensate (BEC) is considered under conditions of Feshbach

resonance in two-atom collisions due to a coupling of atomic pair and resonant

molecular states. The association of condensate atoms can form a molecular BEC,

and the molecules can dissociate to pairs of entangled atoms in two-mode

squeezed states. Both entanglement and squeezing can be applied to quantum

measurements and information processing.

The processes in the atom-molecule quantum gas are analyzed using two

theoretical approaches. The mean-field one takes into account deactivating

collisions of resonant molecules with other atoms and molecules, neglecting

quantum fluctuations. This method allows analysis of inhomogeneous systems,

such as expanding BEC. The non-mean-field approach -- the parametric

approximation -- takes into account both deactivation and quantum fluctuations.

This method allows determination of optimal conditions for formation of

molecular BEC and describes Bose-enhanced dissociation of molecular BEC, as

well as entanglement and squeezing of the non-condensate atoms.

\\ ( http://arXiv.org/abs/cond-mat/0611054 , 439kb)

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\\

Paper: cond-mat/0611058

Date: Thu, 2 Nov 2006 14:51:55 GMT (53kb)

Title: LOFF and breached pairing with cold atoms

Authors: Amruta Mishra and Hiranmaya Mishra

Comments: 18 pages including 10 figures

Subj-class: Superconductivity

\\

We investigate here the Cooper pairing of fermionic atoms with mismatched

fermi surfaces using a variational construct for the ground state. We determine

the state for different values of the mismatch of chemical potential for weak

as well as strong coupling regimes including the BCS BEC cross over region. We

consider both homogeneous and inhomogeneous Cooper pairing. We also show that

LOFF phase is stable in the weak coupling regime and that the LOFF window is

maximum near the strong coupling regime on the BEC side of the Feshbach

resonance.

\\ ( http://arXiv.org/abs/cond-mat/0611058 , 53kb)

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\\

Paper: cond-mat/0611059

Date: Thu, 2 Nov 2006 14:59:14 GMT (50kb)

Title: Mean-field phase diagram for Bose-Hubbard Hamiltonians with random

hopping

Authors: P. Buonsante, F. Massel, V. Penna, A. Vezzani

Comments: 7 pages, 6 figures. Submitted to Laser Physics

Subj-class: Statistical Mechanics; Other

\\

The zero-temperature phase diagram for ultracold Bosons in a random 1D

potential is obtained through a site-decoupling mean-field scheme performed

over a Bose-Hubbard (BH) Hamiltonian whose hopping term is considered as a

random variable. As for the model with random on-site potential, the presence

of disorder leads to the appearance of a Bose-glass phase. The different phases

-i.e. Mott insulator, superfluid, Bose-glass- are characterized in terms of

condensate fraction and superfluid fraction. Furthermore, the boundary of the

Mott lobes are related to an off-diagonal Anderson model featuring the same

disorder distribution as the original BH Hamiltonian.

\\ ( http://arXiv.org/abs/cond-mat/0611059 , 50kb)

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\\

Paper: physics/0611014

Date: Wed, 1 Nov 2006 21:22:51 GMT (753kb)

Title: Synchronous Optical Pumping of Quantum Revival Beats for Atomic

Magnetometery

Authors: S. J. Seltzer, P. J. Meares, M. V. Romalis

Comments: 4 pages

Subj-class: Atomic Physics

\\

We observe quantum beats with periodic revivals due to non-linear spacing of

Zeeman levels in the ground state of potassium atoms and demonstrate their

synchronous optical pumping by double modulation of the pumping light at the

Larmor frequency and the revival frequency. We show that synchronous pumping

increases the degree of spin polarization by a factor of 4. As a practical

example, we explore the application of this double-modulation technique to

atomic magnetometers operating in the geomagnetic field range and find that it

can increase the sensitivity and reduce magnetic field orientation-dependent

measurement errors endemic to alkali-metal magnetometers.

\\ ( http://arXiv.org/abs/physics/0611014 , 753kb)

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The replacements:

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Paper: cond-mat/0602549

replaced with revised version Fri, 27 Oct 2006 13:39:22 GMT (38kb)

Title: Four-boson scale near a Feshbach resonance

Authors: M. T. Yamashita, Lauro Tomio, A. Delfino and T. Frederico

Subj-class: Soft Condensed Matter; Atomic Physics

Journal-ref: Europhys. Lett. 75, 555 (2006)

\\ ( http://arXiv.org/abs/cond-mat/0602549 , 38kb)

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\\\

Paper: cond-mat/0604063

replaced with revised version Fri, 27 Oct 2006 16:00:21 GMT (347kb)

Title: Disorder contra Mermin-Wagner-Hohenberg effect: From classical spin

systems to ultracold atomic gases

Authors: Jan Wehr (University of Arizona, ICFO), Armand Niederberger (ICFO),

Laurent Sanchez-Palencia (LCFIO), Maciej Lewenstein (ICFO)

Comments: significantly expanded version; 8 pages, 3 figures

Proxy: ccsd ccsd-00022177

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0604063 , 347kb)

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\\

Paper: cond-mat/0609052

replaced with revised version Fri, 27 Oct 2006 09:22:11 GMT (22kb)

Title: Quantum Field Theoretical Description of Unstable Behavior of Trapped

Bose-Einstein Condensates with Complex Eigenvalues of Bogoliubov-de Gennes

Equations

Authors: M. Mine, M. Okumura, T. Sunaga, Y. Yamanaka

Comments: 29 pages

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0609052 , 22kb)

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\\

Paper: cond-mat/0610274

replaced with revised version Thu, 26 Oct 2006 20:33:48 GMT (58kb)

Title: Single-plane-wave Larkin-Ovchinnikov-Fulde-Ferrell state in

BCS--Bose-Einstein condensation crossover

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

Comments: 4 pages, 3 figures, some discussions are revised

Subj-class: Strongly Correlated Electrons; Superconductivity

\\ ( http://arXiv.org/abs/cond-mat/0610274 , 58kb)

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\\

Paper: cond-mat/0503264

replaced with revised version Mon, 30 Oct 2006 04:36:27 GMT (73kb)

Title: Finite Temperature Excitations of a trapped Bose gas by Feynman-Kac path

integral approach

Authors: S. Datta

Comments: 35pages,16figures

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0503264 , 73kb)

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\\

Paper: cond-mat/0604273

replaced with revised version Mon, 30 Oct 2006 15:10:43 GMT (267kb)

Title: Topological constraints on magnetostatic traps

Authors: R. Gerritsma and R. J. C. Spreeuw

Comments: 7 pages, 5 figures

Subj-class: Other

Journal-ref: Phys. Rev. A 74, 043405 (2006)

\\ ( http://arXiv.org/abs/cond-mat/0604273 , 267kb)

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\\

Paper: cond-mat/0605056

replaced with revised version Tue, 31 Oct 2006 09:23:18 GMT (758kb)

Title: Dressed molecules in an optical lattice

Authors: K. B. Gubbels, D. B. M. Dickerscheid, and H. T. C. Stoof

Comments: 20 pages, 4 figures

Subj-class: Statistical Mechanics

Journal-ref: New Journal of Physics 8, 151 (2006)

\\ ( http://arXiv.org/abs/cond-mat/0605056 , 758kb)

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\\

Paper: cond-mat/0606757

replaced with revised version Tue, 31 Oct 2006 11:17:47 GMT (114kb)

Title: Control of the interaction in a Fermi-Bose mixture

Authors: M. Zaccanti, C. D'Errico, F. Ferlaino, G.Roati, M. Inguscio, G.

Modugno

Comments: 5 Pages

Subj-class: Other

Journal-ref: PRA 74, 041605(R) (2006)

\\ ( http://arXiv.org/abs/cond-mat/0606757 , 114kb)

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\\

Paper: cond-mat/0609036

replaced with revised version Tue, 31 Oct 2006 05:58:20 GMT (148kb)

Title: Screening effect and delocalization of interacting Bose-Einstein

condensates in random potentials

Authors: Laurent Sanchez-Palencia (LCFIO)

Comments: To appear in Phs. Rev. A; minor changes

Proxy: ccsd ccsd-00090760

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0609036 , 148kb)

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\\

Paper: cond-mat/0610844

replaced with revised version Tue, 31 Oct 2006 02:55:33 GMT (47kb)

Title: A Cold Atomic Fermi Gas with a Spatially Modulated Interaction

Authors: Hao Fu, Alberto G. Rojo

Comments: 11 pages, 3 figures, replaced with eps figures

Subj-class: Superconductivity; Other

\\ ( http://arXiv.org/abs/cond-mat/0610844 , 47kb)

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\\

Paper: quant-ph/0609077

replaced with revised version Tue, 31 Oct 2006 17:31:43 GMT (37kb)

Title: An investigation into why macroscopic systems behave classically

Authors: David W. Hallwood, Keith Burnett, Jacob Dunningham

Comments: 23 preprint pages, 12 figures

\\ ( http://arXiv.org/abs/quant-ph/0609077 , 37kb)

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\\

Paper: cond-mat/0610703

replaced with revised version Wed, 1 Nov 2006 17:39:48 GMT (185kb)

Title: Scattering of two-dimensional solitons in dipolar Bose-Einstein

condensates

Authors: R. Nath, P. Pedri and L. Santos

Comments: 4 pages, 5 eps figures, minor changes

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0610703 , 185kb)

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\\

Paper: cond-mat/0610536

replaced with revised version Thu, 2 Nov 2006 12:09:20 GMT (22kb)

Title: Bose-Einstein condensation of magnons in ferromagnets with easy-plane

anisotropy and in antiferromagnets with weakly coupled ferromagnetic plains

or chains

Authors: A. V. Syromyatnikov

Comments: 5 pages, 1 figure, submitted to PRB, some misprints have been

corrected

Subj-class: Strongly Correlated Electrons

\\ ( http://arXiv.org/abs/cond-mat/0610536 , 22kb)

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Till next week,

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 Mon Nov 06 2006 - 17:43:52 EST

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