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

Date: Sat, 22 Dec 2007 07:03:22 +1000

Date: Sat, 22 Dec 2007 07:03:22 +1000

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

Hi everyone,

I'm very pleased to have achieved my goal and have this week's mailing ready

early: it's been a long time since that happened! The next mailing will be

early in the new year.

This week sees 28 new preprints and 10 replacements. Merry Christmas to everybody!

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arXiv:0712.2250

Date: Thu, 13 Dec 2007 23:16:50 GMT (367kb)

Title: Bose-Einstein Condensation in Magnetic Insulators

Authors: T. Giamarchi, Ch. R\"uegg, O. Tchernyshyov

Categories: cond-mat.str-el

Comments: 17 pages, 3 figures

\\

The elementary excitations in antiferromagnets are magnons, quasiparticles

with integer spin and Bose statistics. In an experiment their density is

controlled efficiently by an applied magnetic field and can be made finite to

cause the formation of a Bose-Einstein condensate (BEC). Studies of magnon

condensation in a growing number of magnetic materials provide a unique window

into an exciting world of quantum phase transitions (QPT) and exotic quantum

states.

\\ ( http://arxiv.org/abs/0712.2250 , 367kb)

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arXiv:0712.2256

Date: Fri, 14 Dec 2007 17:19:16 GMT (192kb)

Title: New type of Bose-Einstein condensation of cold atoms with effective

spin-orbit interactions

Authors: Tudor Stanescu and Victor Galitski

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

Comments: 4 pages, 2 color figures

\\

We consider a many-body system of multi-level Bose-atoms moving in the

presence of spatially modulated laser fields. The light field couples three

hyperfine ground states of an atom to an excited level, leading to the

appearance of a pair of degenerate dark states. The effective many-body

Hamiltonian describes a system of pseudo-spin-1/2 bosons with emergent

spin-orbit interactions, which couple the momentum and the internal pseudo-spin

degree of freedom. The corresponding band structure is generally anisotropic

and contains two minima at finite momenta. At low temperatures, the many-body

system condenses into the double-degenerate single-particle ground states,

leading to a new type of Bose-Einstein condensate. We obtain the corresponding

many-body wave-function describing a condensate of "left-" and "right-moving"

bosons. We also show that by fine-tuning the parameters of the laser field, one

can obtain a bosonic version of the spin-orbit coupled Rashba model. In this

symmetric case, the degeneracy of the ground state is very large, which may

lead to phases with non-trivial topological properties. The predicted states

can be observed experimentally via time-of-flight imaging, which will show

characteristic double-peak or ring-like structures in momentum distribution.

\\ ( http://arxiv.org/abs/0712.2256 , 192kb)

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arXiv:0712.2380

Date: Fri, 14 Dec 2007 16:01:09 GMT (16kb)

Title: A variational Jastrow coupled-cluster theory of quantum many-body

systems

Authors: Y. Xian

Categories: cond-mat.str-el

\\

We study many-body correlations in the ground states of a general quantum

system of bosons or fermions by including an additional Jastrow function in our

ecently proposed variational coupled-cluster method. Our approach combines the

dvantages of state-dependent correlations in the coupled-cluster theory and of

strong, short-ranged correlations of the Jastrow function. We apply a

generalized linked-cluster expansion for the Jastrow wavefunction and provide

detailed analysis for practical evaluation of Hamiltonian expectation value as

an energy functional of the Jastrow function and the bare density-distribution

functions introduced and calculated in our earlier publications; a simple,

first-order energy functional is derived and detailed formulas for higher-order

contributions are provided. Our energy functional does not suffer the

divergence as in most coupled-cluster calculations when applying to

Hamiltonians with hardcore potentials. We also discuss relations between our

energy functional and the energy functionals from other theories.

\\ ( http://arxiv.org/abs/0712.2380 , 16kb)

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arXiv:0712.2443

Date: Fri, 14 Dec 2007 20:16:31 GMT (44kb)

Title: The model of interacting spatial permutations and its relation to the

Bose gas

Authors: Daniel Ueltschi

Categories: cond-mat.stat-mech

Comments: 13 pages

\\

The model of spatial permutations is related to the Feynman-Kac

representation of the Bose gas. The transition to infinite cycles corresponds

to Bose-Einstein condensation. We review the general setting and some results,

and we derive a multi-body interaction between permutation jumps, that is due

to the original interactions between quantum particles.

\\ ( http://arxiv.org/abs/0712.2443 , 44kb)

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arXiv:0712.2093 (*cross-listing*)

Date: Thu, 13 Dec 2007 04:28:36 GMT (94kb)

Title: Effective Lagrangian of unitary Fermi gas from $\varepsilon$ expansion

Authors: Andrei Kryjevski

Categories: nucl-th cond-mat.other

Comments: 17 pages, 4 figures

\\

Using $\varepsilon$ expansion technique proposed in \cite{Nishida:2006br} we

derive an effective Lagrangian (Ginzburg-Landau-like functional) of the

degenerate unitary Fermi gas to the next-to-leading (NLO) order in

$\varepsilon.$ It is demonstrated that for many realistic situations it is

sufficient to retain leading order (LO) terms in the derivative expansion. The

functional is used to study vortex structure in the symmetric gas, and

interface between normal and superfluid phases in the polarized gas. The

resulting surface free energy is about four times larger than the value

previously quoted in the literature.

\\ ( http://arxiv.org/abs/0712.2093 , 94kb)

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arXiv:0712.2400

Date: Fri, 14 Dec 2007 18:50:12 GMT (345kb)

Title: Continuous variable versus EIT-based quantum memories

Authors: Z. Kurucz and M. Fleischhauer

Categories: quant-ph

Comments: 12 pages, 4 figures

\\

We discuss a general model of a quantum memory for a single light mode in a

collective mode of atomic oscillators. The model includes interaction

Hamiltonians that are of second order in the canonical position and momentum

operators of the light- and atomic oscillator modes. We also consider the

possibility of measurement and feedback. We identify an interaction Hamiltonian

that leads to an ideal mapping by pure unitary evolution and compare several

schemes which realize this mapping using a common continuous-variable

description. In particular we discuss schemes based on the off-resonant Faraday

effect supplemented by measurement and feedback and proper preparation of the

atoms in a squeezed state and schemes based on off-resonant Raman coupling as

well as electromagnetically induced transparency (EIT).

\\ ( http://arxiv.org/abs/0712.2400 , 345kb)

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arXiv:0712.2493

Date: Sat, 15 Dec 2007 04:21:56 GMT (85kb)

Title: Evaluation of the Permutational Structure of the Canonical Ensemble

Partition Function

Authors: Ryan Springall, Manolo Per and Ian K. Snook

Categories: cond-mat.stat-mech

Comments: 6 Figures, 8 pages

Journal-ref: Phys. Rev. E 75, 031124 (2007)

\\

Proposed is an alternative method for permutational sampling in quantum gases

using the path integral formulation of statistical mechanics. It is shown that

in principle we are able to use two operators which enable us to construct a

Markov chain through a graph of the irreducible representation of the symmetric

group. As an illustration of this method, a test calculation of four particles

in a harmonic trap is performed.

\\ ( http://arxiv.org/abs/0712.2493 , 85kb)

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arXiv:0712.2495

Date: Sat, 15 Dec 2007 05:50:15 GMT (88kb)

Title: On the Quantum Instability of Attractive Bose Systems

Authors: George E. Cragg and Arthur K. Kerman

Categories: cond-mat.other

Comments: 59 pages, 6 figures

\\

We explore the zero-temperature behavior of an assembly of bosons interacting

through a zero-range, attractive potential. Because the two-body interaction

admits a bound state, the many-body model is best described by a Hamiltonian

that includes the coupling between atomic and molecular components. Due to the

positive scattering length, the low-density collection is expected to remain

stable against collapse despite the attraction between particles. Through a

variational many-body analysis, we find that the usual solution is obtained

only if the chemical potential is allowed to be complex valued. Expanding in

small oscillations reveals that the imaginary part of the chemical potential

signifies a coherent decay of the quantum state into collective phonon

excitations of a collapsing lower state.

\\ ( http://arxiv.org/abs/0712.2495 , 88kb)

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arXiv:0712.2571

Date: Sun, 16 Dec 2007 13:56:41 GMT (810kb,D)

Title: Integer quantum Hall effect in constant non-Abelian "magnetic" fields

Authors: N. Goldman, A. Kubasiak and M. Lewenstein

Categories: cond-mat.mes-hall

Comments: 4 pages, 4 figures

\\

We study a fundamental problem regarding the physics of fermionic atoms in a

constant non-Abelian U(2) "magnetic" field. The energy spectrum reveals a

robust band structure and exhibits large bandgaps. We characterize the integer

quantum Hall effect and the quantized Hall conductivity in such systems by

calculating the Chern numbers associated to the non-Abelian Berry's curvature.

We eventually describe this phenomenon through a striking fractal phase

diagram.

\\ ( http://arxiv.org/abs/0712.2571 , 810kb)

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arXiv:0712.2741

Date: Thu, 13 Dec 2007 20:24:52 GMT (1285kb,D)

Title: Bosons in one-dimensional incommensurate superlattices

Authors: Tommaso Roscilde

Categories: cond-mat.dis-nn cond-mat.str-el

Comments: 22 pages, 28 figures

\\

We investigate numerically the zero-temperature physics of the

one-dimensional Bose-Hubbard model in an incommensurate cosine potential,

recently realized in experiments with cold bosons in optical superlattices L.

Fallani et al., Phys. Rev. Lett. 98, 130404, (2007)]. An incommensurate cosine

potential has intermediate properties between a truly periodic and a fully

random potential, displaying a characteristic length scale (the quasi-period)

which is shown to set a finite lower bound to the excitation energy of the

system at special incommensurate fillings. This leads to the emergence of

gapped incommensurate band-insulator (IBI) phases along with gapless Bose-glass

(BG) phases for strong quasi-periodic potential, both for hardcore and softcore

bosons. Enriching the spatial features of the potential by the addition of a

second incommensurate component appears to remove the IBI regions, stabilizing

a continuous BG phase over an extended parameter range. Moreover we discuss the

validity of the local-density approximation in presence of a parabolic trap,

clarifying the notion of a local BG phase in a trapped system; we investigate

the behavior of first- and second-order coherence upon increasing the strength

of the quasi-periodic potential; and we discuss the ab-initio derivation of the

Bose-Hubbard Hamiltonian with quasi-periodic potential starting from the

microscopic Hamiltonian of bosons in an incommensurate superlattice.

\\ ( http://arxiv.org/abs/0712.2741 , 1285kb)

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arXiv:0712.2486

Date: Sat, 15 Dec 2007 01:01:36 GMT (760kb,D)

Title: Entangling identical bosons in optical tweezers via exchange interaction

Authors: Nathan S. Babcock, Rene Stock, Mark G. Raizen, Barry C. Sanders

Categories: quant-ph

Comments: 9 pages, 3 figures

\\

We first devise a scheme to perform a universal entangling gate via

controlled collisions between pairs of atomic qubits trapped with optical

tweezers. Second, we present a modification to this scheme to allow the

preparation of atomic Bell pairs via selective excitation, suitable for quantum

information processing applications that do not require universality. Both

these schemes are enabled by the inherent symmetries of identical composite

particles, as originally proposed by Hayes et al. Our scheme provides a

technique for producing weighted graph states, entangled resources for quantum

communication, and a promising approach to performing a "loophole free" Bell

test in a single laboratory.

\\ ( http://arxiv.org/abs/0712.2486 , 760kb)

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arXiv:0712.2563

Date: Sun, 16 Dec 2007 10:17:47 GMT (480kb)

Title: Atom--photon momentum entanglement with quantum interference

Authors: Rui Guo and Hong Guo

Categories: quant-ph

Comments: 4 pages, 4 figures

\\

With quantum interference of two-path spontaneous emissions, we propose a

novel scheme to coherently control the atom--photon momentum entanglement

through atomic internal coherence. A novel phenomenon called ``momentum phase

entanglement'' is reported, and we found, under certain conditions, that more

controllable entangled state can be produced with super--high degree of

entanglement.

\\ ( http://arxiv.org/abs/0712.2563 , 480kb)

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arXiv:0712.2565

Date: Sun, 16 Dec 2007 11:06:47 GMT (221kb)

Title: Event-based computer simulation model of Aspect-type experiments

strictly satisfying Einstein's locality conditions

Authors: Hans De Raedt, Koen De Raedt, Kristel Michielsen, Koenraad Keimpema,

and Seiji Miyashita

Categories: quant-ph

Journal-ref: J. Phys. Soc. Jpn. 76, 104005 (2007)

DOI: 10.1143/JPSJ.76.104005

\\

Inspired by Einstein-Podolsky-Rosen-Bohm experiments with photons, we

construct an event-based simulation model in which every essential element in

the ideal experiment has a counterpart. The model satisfies Einstein's criteria

of local causality and does not rely on concepts of quantum and probability

theory. We consider experiments in which the averages correspond to those of a

singlet and product state of a system of two $S=1/2$ particles. The data is

analyzed according to the experimental procedure, employing a time window to

identify pairs. We study how the time window and the passage time of the

photons, which depends on the relative angle between their polarization and the

polarizer's direction, influences the correlations, demonstrating that the

properties of the optical elements in the observation stations affect the

correlations although the stations are separated spatially and temporarily. We

show that the model can reproduce results which are considered to be

intrinsically quantum mechanical.

\\ ( http://arxiv.org/abs/0712.2565 , 221kb)

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arXiv:0712.2574

Date: Sun, 16 Dec 2007 14:21:50 GMT (361kb)

Title: Event-by-event simulation of quantum phenomena

Authors: H. De Raedt

Categories: quant-ph

Comments: V Brazilian Meeting on Simulational Physics, Ouro Preto, 2007

\\

In this talk, I discuss recent progress in the development of simulation

algorithms that do not rely on any concept of quantum theory but are

nevertheless capable of reproducing the averages computed from quantum theory

through an event-by-event simulation. The simulation approach is illustrated by

applications to single-photon Mach-Zehnder interferometer experiments and

Einstein-Podolsky-Rosen-Bohm experiments with photons.

\\ ( http://arxiv.org/abs/0712.2574 , 361kb)

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arXiv:0712.2704

Date: Mon, 17 Dec 2007 12:25:23 GMT (11kb)

Title: On Bargmann Representations of Wigner Function

Authors: Fernando Parisio

Categories: quant-ph

Comments: accepted for publication in J. Phys. A: Math. and Theor

\\

By using the localized character of canonical coherent states, we give a

straightforward derivation of the Bargmann integral representation of Wigner

function (W). A non-integral representation is presented in terms of a

quadratic form V*FV, where F is a self-adjoint matrix whose entries are

tabulated functions and V is a vector depending in a simple recursive way on

the derivatives of the Bargmann function. Such a representation may be of use

in numerical computations. We discuss a relation involving the geometry of

Wigner function and the spacial uncertainty of the coherent state basis we use

to represent it.

\\ ( http://arxiv.org/abs/0712.2704 , 11kb)

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arXiv:0706.0757 (*cross-listing*)

Date: Wed, 6 Jun 2007 15:15:10 GMT (673kb)

Title: Fractional Quantum Hall Effect in Optical Lattices

Authors: Mohammad Hafezi, Anders S. Sorensen, Eugene Demler, Mikhail D. Lukin

Categories: cond-mat.mes-hall quant-ph

Comments: 18 pages, 12 figures

Journal-ref: Phys. Rev. A 76, 023613 (2007)

DOI: 10.1103/PhysRevA.76.023613

\\

We analyze a recently proposed method to create fractional quantum Hall (FQH)

states of atoms confined in optical lattices [A. S{\o}rensen {\it et al.},

Phys. Rev. Lett. {\bf 94} 086803 (2005)]. Extending the previous work, we

investigate conditions under which the FQH effect can be achieved for bosons on

a lattice with an effective magnetic field and finite onsite interaction.

Furthermore, we characterize the ground state in such systems by calculating

Chern numbers which can provide direct signatures of topological order and

explore regimes where the characterization in terms of wavefunction overlap

fails. We also discuss various issues which are relevant for the practical

realization of such FQH states with ultracold atoms in an optical lattice,

including the presence of the long-range dipole interaction which can improve

the energy gap and stabilize the ground state. We also investigate a new

detection technique based on Bragg spectroscopy to probe these system in an

experimental realization.

\\ ( http://arxiv.org/abs/0706.0757 , 673kb)

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arXiv:0712.2915

Date: Tue, 18 Dec 2007 10:16:10 GMT (7kb)

Title: On the Transition to Turbulence of Oscillatory Flow of Liquid Helium-4

Authors: W. Schoepe

Categories: cond-mat.other

\\

Oscillating solid bodies have frequently been used for studying the

properties of normal and superfluid helium. In particular, the transition from

laminar flow to turbulence has attracted much interest recently. The purpose of

this note is to review several central features of this transition in

oscillatory flow, which have been inaccurately formulated in some recent work.

\\ ( http://arxiv.org/abs/0712.2915 , 7kb)

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arXiv:0712.2945

Date: Tue, 18 Dec 2007 12:33:05 GMT (728kb)

Title: Giant vortex and Skyrmion in a rotating two-species Bose-Einstein

condensate

Authors: Shi-Jie Yang, Quan-Sheng Wu, Sheng-Nan Zhang, and Shiping Feng

Categories: cond-mat.other

Comments: 5 pages, 5 figures

\\

Numerical simulations are performed for a rotating two-species Bose

condensate confined by a harmonic potential. The particle numbers of each

species are unequal. When the rotational speed exceeds a critical value, the

majority species reside in the center of the potential while the minority

species is pushed out to the outskirts, forming a giant vortex hole to contain

the majority species. A novel annular Skyrmion forms at the interface of the

two species.

\\ ( http://arxiv.org/abs/0712.2945 , 728kb)

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arXiv:0712.2951

Date: Tue, 18 Dec 2007 13:06:44 GMT (252kb)

Title: Discrete chaotic states of a Bose-Einstein condensate

Authors: Wenhua Hai, Shiguang Rong, Qianquan Zhu

Categories: cond-mat.other

Comments: 4 pages, 5 figures

\\

We find the different chaotic states in a one-dimensional attractive

Bose-Einstein condensate with Gaussian-like laser barrier potential and

perturbed by a weak optical lattice. Existences of the Smale-horseshoe chaos

and the chaotic region of parameters are demonstrated. A bounded chaotic

solution which describes a set of spatially chaotic states is constructed for

the discrete laser barrier heights. The chaotic density profiles are exhibited

numerically for the lowest quantum number, by which the analytically bounded

but numerically unbounded Gaussian-like configurations are illustrated. It is

shown that the amplitude, site and width of the chaotic wave packets can be

controlled experimentally by adjusting the height, site and width of the laser

barrier potential.

\\ ( http://arxiv.org/abs/0712.2951 , 252kb)

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arXiv:0712.3002

Date: Tue, 18 Dec 2007 17:20:49 GMT (409kb)

Title: Collisions of bright solitary matter waves

Authors: N. G. Parker, A. M. Martin, S. L. Cornish and C. S. Adams

Categories: cond-mat.other

Comments: 9 pages, 4 colour figures

\\

The collisions of three-dimensional bright solitary matter waves formed from

atomic Bose-Einstein condensates are shown to exhibit rich behaviour.

Collisions range from being elastic to completely destructive due to the onset

of collapse during the interaction. Through a detailed quantitative analysis we

map out the role of relative phase, impact speed and interaction strength. In

particular, we identify the importance of the collapse time in the onset of

unstable collisions and show how the relative phase controls a population

transfer between the waves. Our analysis enables us to interpret recent

experimental observations of bright solitary matter waves.

\\ ( http://arxiv.org/abs/0712.3002 , 409kb)

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arXiv:0712.2810 (*cross-listing*)

Date: Mon, 17 Dec 2007 20:43:09 GMT (15kb)

Title: Ground state energy of the low density Hubbard model

Authors: Robert Seiringer, Jun Yin

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

Comments: LaTeX2e, 18 pages

\\

We derive a lower bound on the ground state energy of the Hubbard model for

given value of the total spin. In combination with the upper bound derived

previously by Giuliani, our result proves that in the low density limit, the

leading order correction compared to the ground state energy of a

non-interacting lattice Fermi gas is given by $8\pi a \rho_u \rho_d$, where

$\rho_{u(d)}$ denotes the density of the spin-up (down) particles, and $a$ is

the scattering length of the contact interaction potential. This result extends

previous work on the corresponding continuum model to the lattice case.

\\ ( http://arxiv.org/abs/0712.2810 , 15kb)

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arXiv:0712.2956

Date: Tue, 18 Dec 2007 13:26:00 GMT (233kb)

Title: Twin stimulated amplification of light and matter waves in an

atom-photon pair laser

Authors: Thomas Salzburger, Helmut Ritsch

Categories: quant-ph

\\

We consider ultracold atoms in a far detuned optical lattice orientated

across a high-Q optical resonator. Applying an external driving laser to the

atoms, which is red detuned from the cavity mode by one vibrational quantum,

induces cavity-enhanced sideband cooling. For a dense and cold enough atomic

ensemble we predict an oscillation threshold for optical Raman sideband lasing

concurrent with coherent matter-wave amplification. Above this oscillation

threshold photons and atoms in the lowest band are dominantly created pairwise

via stimulated emission with a strong suppression of competing spontaneous

processes. In close analogy to a nondegenerate parametric oscillator we find

sub-Poissonian photon statistics and almost perfect nonclassical atom-photon

number correlations. Injecting atoms in higher vibrational bands via tunneling

or incoherent scattering then leads to continuous, simultaneous generation of a

coherent atom beam and laser light with nonclassical atom-field correlations.

\\ ( http://arxiv.org/abs/0712.2956 , 233kb)

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arXiv:0712.3185

Date: Wed, 19 Dec 2007 13:27:57 GMT (36kb)

Title: Fermions out of Dipolar Bosons in the lowest Landau level

Authors: Brice Chung, Thierry Jolicoeur

Categories: cond-mat.mes-hall

Comments: 12 pages, 5 figures

\\

In the limit of very fast rotation atomic Bose-Einstein condensates may

reside entirely in the lowest two-dimensional Landau level (LLL). For small

enough filling factor of the LLL, one may have formation of fractional quantum

Hall states. We investigate the case of bosons with dipolar interactions as may

be realized with Chromium-52 atoms. We show that at filling factor equal to

unity the ground state is a Moore-Read (a.k.a Pfaffian) paired state as is the

case of bosons with purely s-wave scattering interactions. This Pfaffian state

is destabilized when the interaction in the s-wave channel is small enough and

the ground state is a stripe phase with unidimensional density modulation. For

filling factor 1/3, we show that there is formation of a Fermi sea of

``composite fermions''. These composites are made of one boson bound with three

vortices. This phase has a wide range of stability and the effective mass of

the fermions depends essentially only of the scattering amplitude in momentum

channels larger or equal to 2. The formation of such a Fermi sea opens up a new

possible route to detection of the quantum Hall correlations by direct imaging

of the momentum distribution.

\\ ( http://arxiv.org/abs/0712.3185 , 36kb)

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arXiv:0712.3364

Date: Thu, 20 Dec 2007 10:42:13 GMT (250kb)

Title: Fulde-Ferrell-Larkin-Ovchinnikov superfluidity in one-dimensional

optical lattices

Authors: M. Rizzi, Marco Polini, M.A. Cazalilla, M.R. Bakhtiari, M.P. Tosi,

Rosario Fazio

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

Comments: 7 pages, 5 figures, submitted

\\

Spin-polarized attractive Fermi gases in one-dimensional (1D) optical

lattices are expected to be remarkably good candidates for the observation of

the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase. We model these systems with

an attractive Hubbard model with population imbalance. By means of the

density-matrix renormalization-group method we compute the pairing correlations

as well as the static spin and charge structure factors in the whole range from

weak to strong coupling. We demonstrate that pairing correlations exhibit

quasi-long range order and oscillations at the wave number expected from FFLO

theory. However, we also show by numerically computing the mixed spin-charge

static structure factor that charge and spin degrees of freedom appear to be

coupled already for small imbalance. We discuss the consequences of this

coupling for the observation of the FFLO phase, as well as for the

stabilization of the quasi-long range order into long-range order by coupling

many identical 1D systems, as in quasi-1D optical lattices.

\\ ( http://arxiv.org/abs/0712.3364 , 250kb)

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arXiv:0712.3472

Date: Thu, 20 Dec 2007 15:50:26 GMT (52kb)

Title: Quantum phases of Fermi-Fermi mixtures in optical lattices

Authors: M. Iskin and C. A. R. Sa de Melo

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

Comments: 12 pages with 6 figures. Extended version of arXiv:cond-mat/0612496

\\

The ground state phase diagram of Fermi-Fermi mixtures in optical lattices is

analyzed as a function of interaction strength, population imbalance, filling

fraction and tunneling parameters. It is shown that population imbalanced

Fermi-Fermi mixtures reduce to strongly interacting Bose-Fermi mixtures in the

molecular limit, in sharp contrast to homogeneous or harmonically trapped

systems where the resulting Bose-Fermi mixture is weakly interacting.

Furthermore, insulating phases are found in optical lattices of Fermi-Fermi

mixtures in addition to the standard phase-separated or coexisting

superfluid/excess fermion phases found in homogeneous systems. The insulating

states can be a molecular Bose-Mott insulator (BMI), a Fermi-Pauli insulator

(FPI), a phase-separated BMI/FPI mixture or a Bose-Fermi checkerboard (BFC).

\\ ( http://arxiv.org/abs/0712.3472 , 52kb)

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arXiv:0712.3521

Date: Thu, 20 Dec 2007 18:30:01 GMT (143kb)

Title: All-Optical Production of Chromium Bose-Einstein Condensates

Authors: Q. Beaufils, R. Chicireanu, T. Zanon, B. Laburthe-Tolra, E. Marechal,

L. Vernac, J.-C. Keller, and O. Gorceix

Categories: cond-mat.other

Comments: 4 pages, 4 figures

\\

We report on the production of ^52Cr Bose Einstein Condensates (BEC) with an

all-optical method. We first load 5.106 metastable chromium atoms in a 1D

far-off-resonance optical trap (FORT) from a Magneto Optical Trap (MOT), by

combining the use of Radio Frequency (RF) frequency sweeps and depumping

towards the ^5S_2 state. The atoms are then pumped to the absolute ground

state, and transferred into a crossed FORT in which they are evaporated. The

fast loading of the 1D FORT (35 ms 1/e time), and the use of relatively fast

evaporative ramps allow us to obtain in 20 s about 15000 atoms in an almost

pure condensate.

\\ ( http://arxiv.org/abs/0712.3521 , 143kb)

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arXiv:0712.3436

Date: Thu, 20 Dec 2007 04:47:39 GMT (1212kb)

Title: Bose-Einstein Condensation from a Rotating Thermal Cloud: Vortex

Nucleation and Lattice Formation

Authors: A. S. Bradley, C. W. Gardiner and M. J. Davis

Categories: quant-ph

Comments: 15 pages, 12 figures

\\

We develop a stochastic Gross-Pitaveskii theory suitable for the study of

Bose-Einstein condensation in a {\em rotating} dilute Bose gas. The theory is

used to model the dynamical and equilibrium properties of a rapidly rotating

Bose gas quenched through the critical point for condensation, as in the

experiment of Haljan et al. [Phys. Rev. Lett., 87, 21043 (2001)]. In contrast

to stirring a vortex-free condensate, where topological constraints require

that vortices enter from the edge of the condensate, we find that phase defects

in the initial non-condensed cloud are trapped en masse in the emerging

condensate. Bose-stimulated condensate growth proceeds into a disordered vortex

configuration. At sufficiently low temperature the vortices then order into a

regular Abrikosov lattice in thermal equilibrium with the rotating cloud. We

calculate the effect of thermal fluctuations on vortex ordering in the final

gas at different temperatures, and find that the BEC transition is accompanied

by lattice melting associated with diminishing long range correlations between

vortices across the system.

\\ ( http://arxiv.org/abs/0712.3436 , 1212kb)

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arXiv:0712.3316

Date: Thu, 20 Dec 2007 01:38:11 GMT (194kb)

Title: Site-resolved Bragg scattering

Authors: Birjoo Vaishnav and David S. Weiss

Categories: physics.atom-ph physics.optics

\\

We numerically calculate the reliability with which one can optically

determine the presence or absence of an individual scatterer in a randomly

occupied 3D array of well-localized, coherently radiating scatterers. The

reliability depends in a complicated way on the ratio of lattice spacing to

wavelength and the numerical aperture of the imaging system. The behavior can

be qualitatively understood by considering the dependence of Bragg scattering

modes on lattice spacing. These results are of interest for atomic

implementations of quantum information processing.

\\ ( http://arxiv.org/abs/0712.3316 , 194kb)

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The replacements:

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arXiv:0709.4554

replaced with revised version Fri, 14 Dec 2007 08:05:07 GMT (27kb)

Title: Feshbach resonances in mixtures of ultracold $^6$Li and $^{87}$Rb gases

Authors: B. Deh, C. Marzok, C. Zimmermann and Ph. W. Courteille

Categories: cond-mat.other cond-mat.soft

Comments: 4 pages, 3 figures

\\ ( http://arxiv.org/abs/0709.4554 , 27kb)

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\\

arXiv:0712.0205

replaced with revised version Mon, 17 Dec 2007 09:32:03 GMT (11kb)

Title: Self-consistent equations of unitary fermion thermodynamics with elusive

non-Gaussian correlations

Authors: Ji-sheng Chen, Jia-rong Li, Yan-ping Wang, Xiang-jun Xia

Categories: cond-mat.stat-mech hep-ph nucl-th quant-ph

Comments: Improved version with references updated; typos corrected

\\ ( http://arxiv.org/abs/0712.0205 , 11kb)

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\\

arXiv:0708.3474

replaced with revised version Mon, 17 Dec 2007 04:30:10 GMT (71kb)

Title: Nonlinear control of chaotic walking of atoms in an optical lattice

Authors: Argonov V. Yu, S. V. Prants

Categories: quant-ph

Comments: 6 pages, 4 figures

Journal-ref: Argonov V. Yu, Prants S. V. Nonlinear control of chaotic walking

of atoms in an optical lattice. Europhysics Letters. 2008. Vol. 81. Art. no.

24003

\\ ( http://arxiv.org/abs/0708.3474 , 71kb)

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\\

arXiv:cond-mat/0608335

replaced with revised version Tue, 18 Dec 2007 18:38:11 GMT (215kb)

Title: Mott insulator states of ultracold atoms in optical resonators

Authors: Jonas Larson, Bogdan Damski, Giovanna Morigi, Maciej Lewenstein

Categories: cond-mat.other quant-ph

Comments: 4 pages, 3 figures. Substantially revised version. To appear in Phys.

Rev. Lett

Report-no: LAUR-06-5423

\\ ( http://arxiv.org/abs/cond-mat/0608335 , 215kb)

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\\

arXiv:cond-mat/0703500

replaced with revised version Mon, 17 Dec 2007 23:12:07 GMT (116kb)

Title: Non-equilibrium spin dynamics in a trapped Fermi gas with effective

spin-orbit interaction

Authors: Tudor D. Stanescu, Chuanwei Zhang, and Victor Galitski

Categories: cond-mat.other

Comments: 5 pages, 4 figures; published version

Journal-ref: Phys. Rev. Lett. 99, 110403 (2007)

DOI: 10.1103/PhysRevLett.99.110403

\\ ( http://arxiv.org/abs/cond-mat/0703500 , 116kb)

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\\

arXiv:0711.3431

replaced with revised version Tue, 18 Dec 2007 17:32:15 GMT (148kb)

Title: Dynamics of a symmetry-restoration quantum phase transition in a

ferromagnetic Bose-Einstein condensate

Authors: Bogdan Damski and Wojciech H. Zurek

Categories: cond-mat.other

Comments: 15 pages, 11 figures, rewritten title, expanded introduction, more

references, single-column version, slight changes throughout the paper

Report-no: LAUR-07-7540

\\ ( http://arxiv.org/abs/0711.3431 , 148kb)

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\\

arXiv:0709.2193

replaced with revised version Wed, 19 Dec 2007 01:24:25 GMT (964kb)

Title: Radially Symmetric Nonlinear States of Harmonically Trapped

Bose-Einstein Condensates

Authors: G. Herring, L. D. Carr, R. Carretero-Gonzalez, P. G. Kevrekidis, and

D. J. Frantzeskakis

Categories: cond-mat.other

Comments: 10 pages, 16 figures (some with low resolution)

\\ ( http://arxiv.org/abs/0709.2193 , 964kb)

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\\

arXiv:0707.0458

replaced with revised version Thu, 20 Dec 2007 18:10:56 GMT (51kb)

Title: Number fluctuations in cold quantum gases

Authors: G.E. Astrakharchik, R. Combescot, L.P. Pitaevskii

Categories: cond-mat.stat-mech

Comments: Minor changes due to referee comments

Journal-ref: Phys. Rev. A 76, 063616 (2007)

\\ ( http://arxiv.org/abs/0707.0458 , 51kb)

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\\

arXiv:0710.3047

replaced with revised version Thu, 20 Dec 2007 11:39:18 GMT (299kb)

Title: Quantum stability of self-organized atomic insulator-like states in

optical resonators

Authors: Jonas Larson, Sonia Fernandez-Vidal, Giovanna Morigi, Maciej

Lewenstein

Categories: cond-mat.other quant-ph

Comments: 13 pages, 6 figures. Replaced with revised version. Accepted for

publication in New J. Phys., special issue "Quantum correlations in tailord

matter"

\\ ( http://arxiv.org/abs/0710.3047 , 299kb)

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\\

arXiv:0711.4731

replaced with revised version Thu, 20 Dec 2007 14:53:59 GMT (34kb)

Title: Competing Orders in One-Dimensional Half-Integer Fermionic Cold Atoms: A

Conformal Field Theory Approach

Authors: P. Lecheminant, P. Azaria, and E. Boulat

Categories: cond-mat.str-el hep-th

Comments: 35 pages, 3 figures

\\ ( http://arxiv.org/abs/0711.4731 , 34kb)

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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 Thu Jan 03 2008 - 11:09:23 EST

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