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

Date: Tue, 19 Sep 2006 15:17:34 +1000 (EST)

Date: Tue, 19 Sep 2006 15:17:34 +1000 (EST)

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

So it seems that I am still running a day late....

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

The abstracts for the past week:

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Paper: cond-mat/0609212

Date: Fri, 8 Sep 2006 23:53:00 GMT (98kb)

Title: Exotic Superconducting Phases of Ultracold Atom Mixtures on Triangular

Lattices

Authors: L. Mathey, S.-W. Tsai, A.H. Castro Neto

Comments: 4 pages, 3 figures

Subj-class: Superconductivity

\\

We study the phase diagram of two-dimensional Bose-Fermi mixtures of

ultracold atoms on a triangular optical lattice, in the limit when the velocity

of bosonic condensate fluctuations is much larger than the Fermi velocity.

Using functional renormalization group techniques we show that this phase

diagram contains exotic superconducting phases. For spin-1/2 fermions on an

isotropic lattice we find a competition of $s$-, $p$-, extended $d$-, and

$f$-wave symmetry, as well as antiferromagnetic order. For an anisotropic

lattice, we further find an extended p-wave phase. A Bose-Fermi mixture with

spinless fermions on an isotropic lattice shows a competition between $p$- and

$f$-wave symmetry.

\\ ( http://arXiv.org/abs/cond-mat/0609212 , 98kb)

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Paper: cond-mat/0609218

Date: Sat, 9 Sep 2006 10:14:48 GMT (15kb)

Title: Quantum tunneling of magnetization in dipolar spin-1 condensates under

external fields

Authors: Limin Yang, Yunbo Zhang

Comments: 2 figures, accepted PRA

Subj-class: Other

\\

We study the macroscopic quantum tunneling of magnetization of the F=1 spinor

condensate interacting through dipole-dipole interaction with an external

magnetic field applied along the longitudinal or transverse direction. We show

that the ground state energy and the effective magnetic moment of the system

exhibit an interesting macroscopic quantum oscillation phenomenon originating

from the oscillating dependence of thermodynamic properties of the system on

the vacuum angle. Tunneling between two degenerate minima are analyzed by means

of an effective potential method and the periodic instanton method.

\\ ( http://arXiv.org/abs/cond-mat/0609218 , 15kb)

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Paper: cond-mat/0609219

Date: Sat, 9 Sep 2006 10:23:20 GMT (44kb)

Title: Ground-state Competition of Two-Component Bosons in Optical Lattice near

a Feshbach Resonance

Authors: Liping Guo, Yunbo Zhang, Shu Chen

Comments: 2 figures, submitted to PRA

Subj-class: Other

\\

We investigate the ground state properties of an equal mixture of two species

of bosons in its Mott-insulator phase at a filling factor two per site. We

identify one type of spin triplet-singlet transition through the competition of

ground state. When the on-site interaction is weak ($U<U_c$) the two particles

prefer to stay in the lowest band and with weak tunneling between neighboring

sites the system is mapped into an effective spin-1 ferromagnetic exchange

Hamiltonian. When the interaction is tuned by a Feshbach resonance to be large

enough ($U>U_c$), higher band will be populated. Due to the orbital coupling

term $S^+S^-$ in the Hamiltonian, the two atoms in different orbits on a site

would form an on-site singlet.

\\ ( http://arXiv.org/abs/cond-mat/0609219 , 44kb)

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Paper: cond-mat/0609230

Date: Sun, 10 Sep 2006 15:29:53 GMT (210kb)

Title: Finite-temperature effects on the number fluctuation of ultracold atoms

across the Superfluid to Mott-insulator transition

Authors: Xiancong Lu and Yue Yu

Comments: 6 pages

Subj-class: Other

\\

We study thermodynamics of ultracold Bose atoms in optical lattice by

numerically diagonalizing the mean-field Hamiltonian of the Bose-Hubbard model.

The advantage of this method to the previous finite-temperature perturbation

theory is its validity deep in the superfluid phase. For the homogeneous

Bose-Hubbard model, we draw the finite-temperature phase diagram and calculate

the superfluid density at unity filling. We evaluate the finite-temperature

effects in a recent experiment probing number fluctuation [Phys. Rev. Lett.

\textbf{96}, 090401 (2006)], and find that our theoretical calculations

including the finite-temperature effects are in good agreement with the

experiment results.

\\ ( http://arXiv.org/abs/cond-mat/0609230 , 210kb)

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Paper: cond-mat/0609240

Date: Mon, 11 Sep 2006 17:14:19 GMT (87kb)

Title: Normal-Superfluid Interface Scattering For Polarized Fermion Gases

Authors: Bert Van Schaeybroeck and Achilleas Lazarides

Comments: 4 pages, 3 figures

Subj-class: Other; Superconductivity

\\

The scattering on an interface between a normal (N) and a gapped superfluid

(SF) strongly affects the thermal equilibration process at low temperatures for

fermion gases with population imbalance. Using the Bogoliubov-de Gennes

formalism, we theoretically study the various reflection and transmission

channels for an N-SF interface from the deep BCS to to the unitary regime. We

find that the thermal conductivity drops exponentially fast with increasing

$h/k_B T$, where $h$ is the chemical potential imbalance. It is also argued

that the presence of the interface may, at least at T=0, modify or even cause

the FFLO-like states seen in recent studies.

\\ ( http://arXiv.org/abs/cond-mat/0609240 , 87kb)

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Paper: cond-mat/0609251

Date: Mon, 11 Sep 2006 11:35:54 GMT (9kb)

Title: Collective motions of a quantum gas confined in a harmonic trap

Authors: Dae-Yup Song

Comments: Typos in the printed verions are corrected

Subj-class: Mesoscopic Systems and Quantum Hall Effect; Statistical Mechanics

Journal-ref: Phys. Rev. A 72, 023614 (2005)

DOI: 10.1103/PhysRevA.72.023614

\\

Single-component quantum gas confined in a harmonic potential, but otherwise

isolated, is considered. From the invariance of the system of the gas under a

displacement-type transformation, it is shown that the center of mass

oscillates along a classical trajectory of a harmonic oscillator. It is also

shown that this harmonic motion of the center has, in fact, been implied by

Kohn's theorem. If there is no interaction between the atoms of the gas, the

system in a time-independent isotropic potential of frequency $\nu_c$ is

invariant under a squeeze-type unitary transformation, which gives collective

{\it radial} breathing motion of frequency $2\nu_c$ to the gas. The amplitudes

of the oscillating and breathing motions from the {\it exact} invariances could

be arbitrarily large. For a Fermi system, appearance of $2\nu_c$ mode of the

large breathing motion indicates that there is no interaction between the

atoms, except for a possible long-range interaction through the

inverse-square-type potential.

\\ ( http://arXiv.org/abs/cond-mat/0609251 , 9kb)

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Paper: cond-mat/0609253

Date: Mon, 11 Sep 2006 11:45:04 GMT (8kb)

Title: Exact coherent states of a noninteracting Fermi gas in a harmonic trap

Authors: Dae-Yup Song

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\

Exact and closed-form expressions of the particle density, the kinetic energy

density, the probability current density, and the momentum distribution are

derived for a coherent state of a noninteracting Fermi gas, while such a state

can be obtained from the ground state in a $d$-dimensional isotropic harmonic

trap by modulating the trap frequency and shifting the trap center.

Conservation laws for the relations of the densities are also given. The

profile of the momentum distribution turns out to be identical in shape with

that of the particle density, however, %as an observable manifestation of the

uncertainty principle, the dispersion of the distribution increases (decreases)

when that of the particle density is decreased (increased). The expressions are

also applicable for a sudden and total opening of the trap, and it is shown

that, after the opening, the gas has a stationary momentum distribution whose

dispersion could be arbitrarily large or small.

\\ ( http://arXiv.org/abs/cond-mat/0609253 , 8kb)

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Paper: cond-mat/0609259

Date: Mon, 11 Sep 2006 19:04:22 GMT (259kb)

Title: Dual-species quantum degeneracy of potassium-40 and rubidium-87 on an

atom chip

Authors: M. H. T. Extavour, L. J. LeBlanc, T. Schumm, B. Cieslak, S. Myrskog,

A. Stummer, S. Aubin, J. H. Thywissen

Comments: 8 pages, 4 figures. To be published in the Proceedings of the 20th

International Conference on Atomic Physics, 2006 (Innsbruck, Austria)

Subj-class: Statistical Mechanics

\\

In this article we review our recent experiments with a 40K-87Rb mixture. We

demonstrate rapid sympathetic cooling of a 40K-87Rb mixture to dual quantum

degeneracy on an atom chip. We also provide details on efficient BEC

production, species-selective magnetic confinement, and progress toward

integration of an optical lattice with an atom chip. The efficiency of our

evaporation allows us to reach dual degeneracy after just 6 s of evaporation -

more rapidly than in conventional magnetic traps. When optimizing evaporative

cooling for efficient evaporation of 87Rb alone we achieve BEC after just 4 s

of evaporation and an 8 s total cycle time.

\\ ( http://arXiv.org/abs/cond-mat/0609259 , 259kb)

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Paper: cond-mat/0604580

replaced with revised version Sat, 9 Sep 2006 08:13:47 GMT (16kb)

Title: Superfluidity in a Three-flavor Fermi Gas with SU(3) Symmetry

Authors: Lianyi He, Meng Jin and Pengfei Zhuang

Comments: 9 pages, 2 figures, published version

Subj-class: Other; Superconductivity; Atomic Physics

Journal-ref: Phys. Rev. A 74, 033604 (2006)

DOI: 10.1103/PhysRevA.74.033604

\\ ( http://arXiv.org/abs/cond-mat/0604580 , 16kb)

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Paper: cond-mat/0606624

replaced with revised version Sun, 10 Sep 2006 02:00:40 GMT (27kb)

Title: Asymmetric two-component Fermi gas with unequal masses

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

Comments: 4 pages and 4 figures

Subj-class: Superconductivity; Other

\\ ( http://arXiv.org/abs/cond-mat/0606624 , 27kb)

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Paper: cond-mat/0607542

replaced with revised version Mon, 11 Sep 2006 05:40:43 GMT (25kb)

Title: Analytic solutions of the 1D finite coupli,ng delta function Bose gas

Authors: P. J. Forrester, N. E. Frankel and M. I. Makin

Comments: 23 pages, 0 figures, uses rotate.sty. A few lines added. Accepted by

Phys. Rev. A

Subj-class: Statistical Mechanics; Mathematical Physics

\\ ( http://arXiv.org/abs/cond-mat/0607542 , 25kb)

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Paper: quant-ph/0609077

Date: Mon, 11 Sep 2006 12:35:22 GMT (34kb)

Title: An investigation into why macroscopic systems behave classically

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

Comments: 12 pages, 12 figures

\\

We study why it is hard to make a macroscopic superposition of superfluid

flows in a Bose-Einstein condensate. Initially we investigate N atoms trapped

in a simple 1D ring with a barrier at one point and a phase applied around it.

Perturbation theory is used to show that quasi-momentum (or flow) macroscopic

superpositions can be made and we investigate factors which affect the cat

state. The 1D ring is improved using the Bose-Hubbard model to study an array

of Bose-Einstein condensates trapped in optical potentials and coupled to one

another to form a ring. We derive an analytic expression to describe the

quality of the cat, which agrees well with direct diagonalisation of the

Hamiltonian for relatively small numbers of atoms. We show that for macroscopic

superposition to be realised there are three factors that are required, other

than an absence of decoherence, which become harder to satisfy when the system

size increases. These are, (1) the energies of the two macroscopic states must

be similar, (2) coupling between the two macroscopic states must be strong, and

(3) other states must not be strongly coupled to the macroscopic states. The

results help us to understand quantum mechanics on a macroscopic level.

\\ ( http://arXiv.org/abs/quant-ph/0609077 , 34kb)

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Paper: cond-mat/0609290

Date: Tue, 12 Sep 2006 16:07:30 GMT (83kb)

Title: Renormalized atomic interaction and quadrupole excitations of cold Fermi

gas near Feshbach resonance

Authors: Lai-Wa Siu, T. T. S. Kuo, B. A. Gelman

Comments: 4 pages, 3 figures

Subj-class: Other

\\

We present a model space particle-hole Green's function calculation for the

quadrupole excitations of cold Fermi gas near Feshbach resonance using a simple

model where atoms are confined in a harmonic oscillator potential. Both the

Tamm-Dancoff and random phase approximations are employed. By summing up

exactly the ladder diagrams between a pair of interacting atoms to all orders,

we obtain a renormalized atomic interaction which has well defined and

identical limits as the scattering length tends to $\pm \infty$. The

experimentally observed abrupt rise in the excitation spectrum and its

associated large decay width are satisfactorily reproduced by our calculation.

\\ ( http://arXiv.org/abs/cond-mat/0609290 , 83kb)

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Paper: quant-ph/0609095

Date: Tue, 12 Sep 2006 16:23:58 GMT (331kb)

Title: Optical signatures of quantum phase transitions in a light-matter system

Authors: Timothy C. Jarrett, Alexandra Olaya-Castro and Neil F. Johnson

Comments: 4 pages, 4 figures

\\

Information about quantum phase transitions in conventional condensed matter

systems, must be sought by probing the matter system itself. By contrast, we

show that mixed matter-light systems offer a distinct advantage in that the

photon field carries clear signatures of the associated quantum critical

phenomena. Having derived an accurate, size-consistent Hamiltonian for the

photonic field in the well-known Dicke model, we predict striking behavior of

the optical squeezing and photon statistics near the phase transition. The

corresponding dynamics resemble those of a degenerate parametric amplifier. Our

findings boost the motivation for exploring exotic quantum phase transition

phenomena in atom-cavity, nanostructure-cavity, and

nanostructure-photonic-band-gap systems.

\\ ( http://arXiv.org/abs/quant-ph/0609095 , 331kb)

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Paper: quant-ph/0603156

replaced with revised version Tue, 12 Sep 2006 04:24:25 GMT (22kb)

Title: Implementing the one-dimensional quantum (Hadamard) walk using a

Bose-Einstein Condensate

Authors: C.M. Chandrashekar

Comments: 7 pages, 3 figures

Journal-ref: Phys. Rev. A . 74, 032307 (2006)

\\ ( http://arXiv.org/abs/quant-ph/0603156 , 22kb)

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Paper: cond-mat/0609307

Date: Wed, 13 Sep 2006 05:17:04 GMT (220kb)

Title: Hidden order in one dimensional Bose insulators

Authors: Emanuele G. Dalla Torre, Erez Berg, Ehud Altman

Comments: Letter

Subj-class: Other; Strongly Correlated Electrons

\\

We investigate the phase diagram of spinless bosons with long range (~ 1/r^3)

repulsive interactions, relevant to ultracold polarized atoms or molecules,

using DMRG. Between the two conventional insulating phases, the Mott and

density wave phases, we find a new phase possessing hidden order revealed by

non local string correlations analogous to those characterizing the Haldane

gapped phase of integer spin chains. We develop a mean field theory that

describes the low energy excitations in all three insulating phases. This is

used to calculate the absorption spectrum due to oscillatory lattice

modulation. We predict a sharp resonance in the spectrum due to a collective

excitation of the new phase that would provide clear evidence for the existence

of this phase.

\\ ( http://arXiv.org/abs/cond-mat/0609307 , 220kb)

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Paper: cond-mat/0609313

Date: Wed, 13 Sep 2006 08:34:56 GMT (70kb)

Title: Dynamically stable multiply quantized vortices in dilute Bose-Einstein

condensates

Authors: J. A. M. Huhtam\"aki (1), M. M\"ott\"onen (1 and 2) and S. M. M.

Virtanen (1)

Comments: 5 pages, 6 figures

Subj-class: Statistical Mechanics

\\

Multiquantum vortices in dilute atomic Bose-Einstein condensates confined in

long cigar-shaped traps are known to be both energetically and dynamically

unstable. They tend to split into single-quantum vortices even in the ultralow

temperature limit with vanishingly weak dissipation, which has also been

confirmed in the recent experiments [Y. Shin et al., Phys. Rev. Lett. 93,

160406 (2004)] utilizing the so-called topological phase engineering method to

create multiquantum vortices. We study the stability properties of multiquantum

vortices in different trap geometries by solving the Bogoliubov excitation

spectra for such states. We find that there are regions in the trap asymmetry

and condensate interaction strength plane in which the splitting instability of

multiquantum vortices is suppressed, and hence they are dynamically stable. For

example, the doubly quantized vortex can be made dynamically stable even in

spherical traps within a wide range of interaction strength values. We expect

that this suppression of vortex-splitting instability can be experimentally

verified.

\\ ( http://arXiv.org/abs/cond-mat/0609313 , 70kb)

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Paper (*cross-listing*): nlin.PS/0609032

Date: Tue, 12 Sep 2006 15:39:15 GMT (213kb)

Title: Fano blockade by a Bose-Einstein condensate in an optical lattice

Authors: Rodrigo A. Vicencio, Joachim Brand, and Sergej Flach

Comments: 4 pages, 4 figures (fig4 was resized for arXiv)

Subj-class: Pattern Formation and Solitons; Other

\\

We study the transport of atoms across a localized Bose-Einstein condensate

in a one-dimensional optical lattice. For atoms scattering off the condensate

we predict total reflection as well as full transmission for certain parameter

values on the basis of an exactly solvable model. The findings of analytical

and numerical calculations are interpreted by a tunable Fano-like resonance and

may lead to interesting applications for blocking and filtering atom beams.

\\ ( http://arXiv.org/abs/nlin/0609032 , 213kb)

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Paper: cond-mat/0604137

replaced with revised version Wed, 13 Sep 2006 03:15:16 GMT (28kb)

Title: Fermion Cooper Pairing with Unequal Masses: Standard Field Theory

Approach

Authors: Lianyi He, Meng Jin and Pengfei Zhuang

Comments: 13 pages, 2 figures, published version, erratum will appear soon

Subj-class: Superconductivity; Atomic Physics

Journal-ref: Phys. Rev. B 74, 024516 (2006)

DOI: 10.1103/PhysRevB.74.024516

\\ ( http://arXiv.org/abs/cond-mat/0604137 , 28kb)

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Paper: cond-mat/0604673

replaced with revised version Wed, 13 Sep 2006 14:54:38 GMT (283kb)

Title: Evolution from a Bose-Einstein Condensate to a Tonks-Girardeau Gas: An

Exact Diagonalization Study

Authors: Frank Deuretzbacher, Kai Bongs, Klaus Sengstock, Daniela Pfannkuche

Comments: 5 pages, 5 figures

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0604673 , 283kb)

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Paper: cond-mat/0606281

replaced with revised version Wed, 13 Sep 2006 00:35:41 GMT (867kb)

Title: A Primary Noise Thermometer for Ultracold Bose Gases

Authors: R. Gati, J. Esteve, B. Hemmerling, T. B. Ottenstein, J. Appmeier, A.

Weller, M. K. Oberthaler

Comments: 19 pages, 8 figures

Subj-class: Other

DOI: 10.1088/1367-2630/8/9/189

\\ ( http://arXiv.org/abs/cond-mat/0606281 , 867kb)

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Paper: quant-ph/0609101

Date: Wed, 13 Sep 2006 14:55:43 GMT (364kb)

Title: Anyonic Braiding in Optical Lattices

Authors: Chuanwei Zhang, V.W. Scarola, Sumanta Tewari and S. Das Sarma

Comments: 18 pages, 5 figures

\\

Quantum computers are predicted to utilize intrinsically quantum mechanical

properties of matter to perform difficult computational tasks exponentially

faster than ordinary computers. Isolating and manipulating the delicate quantum

states of individual quantum bits as well as carrying out the necessary quantum

error correction essential for quantum computation require a daunting amount of

precision. Topological quantum computation proposes to use braiding of

collective excitations implanted in topologically ordered coherent quantum

states of many particles, as opposed to a single particle, to perform quantum

computation. Here we explicitly work out how to manipulate and detect

topological excitations in a specific system, cold atom optical lattices. A key

feature of these topological excitations is their braiding statistics, how they

behave when one excitation is taken around another. An observation of the

non-trivial braiding statistics described in this Letter would directly

establish the existence of anyons, quantum particles which are neither fermions

nor bosons. Demonstrating anyonic braiding statistics is tantamount to

observing a new form of matter, topological matter. Once created, excitations

in quantum topological matter, as opposed to delicate single particle quantum

states, can provide a much more robust way to encode and manipulate quantum

information.

\\ ( http://arXiv.org/abs/quant-ph/0609101 , 441kb)

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Paper: cond-mat/0609337

Date: Thu, 14 Sep 2006 07:09:15 GMT (385kb)

Title: Quantum Entanglement Manifestation of Transition to Nonlinear

Self-trapping for Bose-Einstein Condensates in a Symmetric Double-Well

Authors: Li-Bin Fu and Jie Liu

Comments: 6 pages, 5 figures

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\

We investigate the nonlinear self-trapping phenomenon of the Bose-Einstein

condensates (BEC) in a symmetric double-well, emphasizing on its behind

dynamical phase transition. With increasing the nonlinear parameter depicting

the interaction between the degenerate atoms the BEC turns to be self-trapped

manifesting an asymmetric distribution of the atomic density profile. Essence

of this phenomenon is revealed to be a continuous phase transition and

underlying critical behavior is studied analytically and found to follow a

logarithm scaling-law. We then go beyond the mean field treatment and extend to

discuss the effect of the many-body quantum fluctuation on the transition. It

is found that the transition point is shifted and the scaling-law is broken. In

particular, the quantum phase transition is accompanied by the change of the

entanglement entropy which is found to reach maximum at transition point.

Behind physics is revealed.

\\ ( http://arXiv.org/abs/cond-mat/0609337 , 385kb)

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Paper: cond-mat/0609338

Date: Thu, 14 Sep 2006 07:22:19 GMT (318kb)

Title: Continuous measurements enhanced self-trapping of degenerate ultra-cold

atoms: Nonlinear Quantum Zeno Effect

Authors: WeiDong Li and Jie Liu

Comments: 7 pages, 8 figures

Subj-class: Mesoscopic Systems and Quantum Hall Effect; Other

\\

In the present paper we investigate the influence of measurements on the

quantum dynamics of degenerate bose atoms gases in a symmetric double-well. We

show that continuous measurement could induce an asymmetric distribution of the

atoms density profile and broaden the parameter regime for self-trapping. We

term this phenomenon as nonlinear quantum Zeno effect in analog to the

celebrated Zeno effect in a linear quantum system. Under a discontinuous

measurement, the self-trapping due to the atomic interaction in the degenerate

bosons is shown to be destroyed completely. Underlying physics is revealed and

possible experimental realization is discussed.

\\ ( http://arXiv.org/abs/cond-mat/0609338 , 318kb)

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Paper: cond-mat/0609340

Date: Thu, 14 Sep 2006 07:48:59 GMT (114kb)

Title: The stationary solutions of G-P equations in double square well

Authors: Weidong Li

Comments: 7 pages, 4 figures. accepted by Phys. Rev. A. (2006)

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\

We present new analytical stationary solutions for the Gross-Pitaevskii

equation (GPE) of a Bose-Einstein condensate (BEC) trapped in a double-well

potential. These solutions are compared with those described by Mahmud et al.,

PRA 66, 063607 (2002). In particular, we provide further evidences that

symmetry preserving stationary solutions can be reduced to the eigenstates of

the corresponding linear Schrodinger equation. Moreover, we found that the

symmetry breaking solutions can emerge not only from bifurcations, but also

from isolated points in the chemical potential-nonlinear interaction diagram.

We also found that there are some moving nodes in the symmetry breaking

solutions.

\\ ( http://arXiv.org/abs/cond-mat/0609340 , 114kb)

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Paper: cond-mat/0609346

Date: Thu, 14 Sep 2006 12:42:59 GMT (169kb)

Title: Luther-Emery Phase and Atomic-Density Waves in a Trapped Fermion Gas

Authors: Gao Xianlong, M. Rizzi, Marco Polini, Rosario Fazio, M.P. Tosi, V.L.

Campo Jr., K. Capelle

Comments: 10 pages, 3 figures, 1 Table, submitted to Phys. Rev. on July 25th

2006

Subj-class: Strongly Correlated Electrons; Superconductivity

\\

The Luther-Emery liquid is a state of matter that is predicted to occur in

one-dimensional systems of interacting fermions and is characterized by a

gapless charge spectrum and a gapped spin spectrum. In this Letter we discuss a

realization of the Luther-Emery phase in a trapped cold-atom gas. We study by

means of the density-matrix renormalization-group technique a two-component

atomic Fermi gas with attractive interactions subject to parabolic trapping

inside an optical lattice. We demonstrate how this system exhibits compound

phases characterized by the coexistence of spin pairing and atomic-density

waves. A smooth crossover occurs with increasing magnitude of the atom-atom

attraction to a state in which tightly bound spin-singlet dimers occupy the

center of the trap. The existence of atomic-density waves could be detected in

the elastic contribution to the light-scattering diffraction pattern.

\\ ( http://arXiv.org/abs/cond-mat/0609346 , 169kb)

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Paper (*cross-listing*): nlin.PS/0609031

Date: Tue, 12 Sep 2006 14:43:16 GMT (936kb)

Title: Simple and efficient generation of gap solitons in Bose-Einstein

condensates

Authors: Michal Matuszewski, Wieslaw Krolikowski, Marek Trippenbach, Yuri S.

Kivshar

Comments: 7 pages, 10 figures

Subj-class: Pattern Formation and Solitons; Other

Journal-ref: Phys. Rev. A 73, 063621 (2006)

DOI: 10.1103/PhysRevA.73.063621

\\

We suggest an efficient method for generating matter-wave gap solitons in a

repulsive Bose-Einstein condensate, when the gap soliton is formed from a

condensate cloud in a harmonic trap after turning on a one-dimensional optical

lattice. We demonstrate numerically that this approach does not require

preparing the initial atomic wave packet in a specific state corresponding to

the edge of the Brillouin zone of the spectrum, and losses that occur during

the soliton generation process can be suppressed by an appropriate adiabatic

switching of the optical lattice.

\\ ( http://arXiv.org/abs/nlin/0609031 , 936kb)

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Paper: cond-mat/0507399

replaced with revised version Wed, 13 Sep 2006 20:40:42 GMT (24kb)

Title: The unitary three-body problem in a trap

Authors: F\'{e}lix Werner (LKB - Lhomond), Yvan Castin (LKB - Lhomond)

Comments: 4 pages, version including a prediction for the lifetime of an

Efimovian state

Proxy: ccsd ccsd-00007574

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0507399 , 24kb)

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Paper: cond-mat/0606677

replaced with revised version Thu, 14 Sep 2006 11:12:25 GMT (636kb)

Title: Response of Bose gases in time-dependent optical superlattices

Authors: M. Hild, F. Schmitt, R. Roth

Comments: 20 pages, 9 figures; added references and corrected typos

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0606677 , 636kb)

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Paper: cond-mat/0607251

replaced with revised version Thu, 14 Sep 2006 15:20:22 GMT (49kb)

Title: Quantum Phase Transitions of Hard-Core Bosons in Background Potentials

Authors: Anand Priyadarshee, Shailesh Chandrasekharan, Ji-Woo Lee, and Harold

U. Baranger

Comments: 4 pages (6 figures); published version-- 2 references added, minor

clarifications

Subj-class: Statistical Mechanics; Superconductivity

Journal-ref: Phys. Rev. Lett. 97, 115703 (2006)

DOI: 10.1103/PhysRevLett.97.115703

\\ ( http://arXiv.org/abs/cond-mat/0607251 , 49kb)

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Paper: cond-mat/0608542

replaced with revised version Thu, 14 Sep 2006 12:58:01 GMT (169kb)

Title: Three-boson recombination at ultralow temperatures

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

Subj-class: Soft Condensed Matter

\\ ( http://arXiv.org/abs/cond-mat/0608542 , 169kb)

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Paper: cond-mat/0609230

replaced with revised version Thu, 14 Sep 2006 04:50:40 GMT (210kb)

Title: Finite-temperature effects on the number fluctuation of ultracold atoms

across the Superfluid to Mott-insulator transition

Authors: Xiancong Lu and Yue Yu

Comments: 7 pages,7 figures, minor changes

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0609230 , 210kb)

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Paper: quant-ph/0609103

Date: Thu, 14 Sep 2006 00:38:22 GMT (132kb)

Title: Opacity of electromagnetically induced transparency for quantum

fluctuations

Authors: P. Barberis-Blostein and M. Bienert

\\

We analyze the propagation of a pair of quantized fields inside a medium of

three-level atoms in $\Lambda$ configuration. We calculate the stationary

quadrature noise spectrum of the field after propagating through the medium, in

the case where the probe field is in a squeezed state and the atoms show

electromagnetically induced transparency (EIT). We find an oscillatory transfer

of the initial quantum properties between the probe and pump fields which is

most strongly pronounced when both fields have comparable Rabi frequencies.

This implies that the quantum state measured after propagation can be

completely different from the initial state, even though the mean values of the

field are unaltered.

\\ ( http://arXiv.org/abs/quant-ph/0609103 , 132kb)

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\\

Paper: quant-ph/0603129

replaced with revised version Thu, 14 Sep 2006 01:34:17 GMT (25kb)

Title: Adiabatic Mach-Zehnder Interferometry on A Quantized Bose-Josephson

Junction

Authors: Chaohong Lee

Comments: Revised version, 4 pages, 4 figures, Accepted for publication in

Physical Review Letters

\\ ( http://arXiv.org/abs/quant-ph/0603129 , 25kb)

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\\

Paper: physics/0609120

Date: Thu, 14 Sep 2006 10:39:29 GMT (34kb)

Title: Time invariance violation is a physical base of atomic Bloch

oscillations in an optical lattice

Authors: V.A.Kuz'menko

Comments: 3 pages, 1 figure

Subj-class: General Physics; Optics

\\

The physical mechanism of phenomenon is explained as a result of inequality

of forward and reversed processes in optics. The importance of experimental

study of its invariance relation is discussed.

\\ ( http://arXiv.org/abs/physics/0609120 , 34kb)

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\\

Paper: physics/0609116

Date: Thu, 14 Sep 2006 10:28:13 GMT (66kb)

Title: On the Dynamics of the $h-$index in Complex Networks with Coexisting

Communities

Authors: Luciano da Fontoura Costa

Comments: 9 pages, 1 table, 2 figures. A working manuscript: comments and

criticisms are welcomed

Subj-class: Physics and Society

\\

This article investigates the evolution of the $h-$index in a complex network

including two communities (in the sense of having different features) with the

same number of authors whose yearly productions follow the Zipf's law. Models

considering indiscriminate citations, as well as citations preferential to the

fitness values of each community and/or the number of existing citations are

proposed and numerically simulated. The $h-$indices of each type of author is

estimated along a period of 20 years, while the number of authors remains

constant. Interesting results are obtained including the fact that, for the

model where citations are preferential to both community fitness and number of

existing citations per article, the $h-$indices of the community with the

largest fitness value are only moderately increased while the indices of the

other community are severely and irreversibly limited to low values. Three

possible strategies are discussed in order to change this situation. In

addition, based on such findings, a new version of the $h-$index is proposed

involving the automated identification of virtual citations which can provide

complementary and unbiased quantification of the relevance of scientific works.

\\ ( http://arXiv.org/abs/physics/0609116 , 66kb)

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Paper: cond-mat/0609373

Date: Fri, 15 Sep 2006 10:53:57 GMT (151kb)

Title: Pair Excitations and Vertex Corrections in Fermi Fluids

Authors: Helga M. B\"ohm, Eckhard Krotscheck, and Martin Panholzer

Comments: to be published in: JLTP (2007) Proc. Int. Symp. QFS2006, 1-6 Aug.

2006, Kyoto, Japan

Subj-class: Other

\\

Based on an equations--of--motion approach for time--dependent pair

correlations in strongly interacting Fermi liquids, we have developed a theory

for describing the excitation spectrum of these systems. Compared to the known

``correlated'' random--phase approximation (CRPA), our approach has the

following properties: i) The CRPA is reproduced when pair fluctuations are

neglected. ii) The first two energy--weighted sumrules are fulfilled implying a

correct static structure. iii) No ad--hoc assumptions for the effective mass

are needed to reproduce the experimental dispersion of the roton in 3He. iv)

The density response function displays a novel form, arising from vertex

corrections in the proper polarisation. Our theory is presented here with

special emphasis on this latter point. We have also extended the approach to

the single particle self-energy and included pair fluctuations in the same way.

The theory provides a diagrammatic superset of the familiar GW approximation.

It aims at a consistent calculation of single particle excitations with an

accuracy that has previously only been achieved for impurities in Bose liquids.

\\ ( http://arXiv.org/abs/cond-mat/0609373 , 151kb)

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\\

Paper: cond-mat/0609374

Date: Fri, 15 Sep 2006 11:15:22 GMT (443kb)

Title: Bose-Einstein Condensation Temperature of Dipolar Gas in Anisotropic

Harmonic Trap

Authors: Konstantin Glaum, Axel Pelster

Comments: Author information under

http://www.theo-phys.uni-essen.de/tp/ags/pelster_dir

Subj-class: Statistical Mechanics

\\

We consider a dilute gas of dipole moments in an arbitrary harmonic trap and

treat both the short-range, isotropic delta-interaction and the long-range,

anisotropic dipole-dipole interaction perturbatively. With this we calculate

the leading shift of the critical temperature with respect to that of an ideal

gas as a function of the relative orientation of the dipole moments with

respect to the harmonic trap axes. In particular, we determine those magic

angles, where the dipolar shift of the Bose-Einstein condensation temperature

vanishes. Furthermore, we show for the parameters of the ongoing

52Cr-experiment in Stuttgart that this dipolar shift can be enhanced by

increasing the number of particles, the geometrical mean trap frequency, and

the anisotropy of the trap.

\\ ( http://arXiv.org/abs/cond-mat/0609374 , 443kb)

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\\

Paper: cond-mat/0609390

Date: Fri, 15 Sep 2006 19:41:56 GMT (78kb)

Title: Precision Measurements of Collective Oscillations in the BEC-BCS

crossover

Authors: A. Altmeyer, S. Riedl, C. Kohstall, M. Wright, R. Geursen, M.

Bartenstein, C. Chin, J. Hecker Denschlag, R. Grimm

Subj-class: Other; Superconductivity

\\

We report on precision measurements of the frequency of the radial

compression mode in a strongly interacting, optically trapped Fermi gas of Li-6

atoms. Our results allow for a test of theoretical predictions for the equation

of state in the BEC-BCS crossover. We confirm recent quantum Monte-Carlo

results and rule out simple mean-field BCS theory. Our results show the

long-sought beyond-mean-field effects in the strongly interacting BEC regime.

\\ ( http://arXiv.org/abs/cond-mat/0609390 , 78kb)

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\\

Paper: cond-mat/0510315

replaced with revised version Fri, 15 Sep 2006 07:21:48 GMT (14kb)

Title: Superfluidity in a gas of strongly-interacting bosons

Authors: G. M. Kavoulakis, Y. Yu, M. Ogren and S. M. Reimann (LTH, Lund)

Comments: 7 pages, 3 figures, revised version, to appear in Europh. Lett

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0510315 , 14kb)

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\\

Paper: cond-mat/0602080

replaced with revised version Fri, 15 Sep 2006 17:35:58 GMT (51kb)

Title: Squeezing in the weakly interacting uniform Bose condensate

Authors: Masudul Haque (Utrecht), Andrei E. Ruckenstein (Rutgers)

Comments: 8 pages, 3 figures. Version 2 (Sept'06): expanded discussions

Subj-class: Statistical Mechanics; Other

\\ ( http://arXiv.org/abs/cond-mat/0602080 , 51kb)

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\\

Paper: quant-ph/0609111

Date: Thu, 14 Sep 2006 23:53:40 GMT (444kb)

Title: Quantum logic via the exchange blockade in ultracold collisions

Authors: David Hayes, Paul Julienne, Ivan Deutsch

\\

A nuclear spin can act as a quantum switch that turns on or off ultracold

collisions between atoms even when there is neither interaction between nuclear

spins nor between the nuclear and electron spins. This "exchange blockade" is a

new mechanism for implementing quantum logic gates that arises from the

symmetry of composite identical particles, rather than direct coupling between

qubits. We study the implementation of the entangling $\sqrt{\text{SWAP}}$ gate

based on this mechanism for a model system of two atoms with ground electron

configuration $^1S_0$, spin 1/2 nuclei, trapped in optical tweezers. We

evaluate a proof-of-principle protocol based on adiabatic evolution of a one

dimensional double Gaussian well, calculating fidelities of operation as a

function of interaction strength, gate time, and temperature.

\\ ( http://arXiv.org/abs/quant-ph/0609111 , 444kb)

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\\

Paper: physics/0609133

Date: Fri, 15 Sep 2006 11:26:18 GMT (956kb)

Title: Laser cooling and trapping of atomic strontium for ultracold atom

physics, high-precision spectroscopy and quantum sensors

Authors: F. Sorrentino, G. Ferrari, N. Poli, R. Drullinger, and G. M. Tino

Comments: 34 pages, 19 figures

Subj-class: Atomic Physics

\\

This review describes the production of atomic strontium samples at ultra-low

temperature and at high phase-space density, and their possible use for

physical studies and applications. We describe the process of loading a

magneto-optical trap from an atomic beam and preparing the sample for high

precision measurements. Particular emphasis is given to the applications of

ultracold Sr samples, spanning from optical frequency metrology to force

sensing at micrometer scale.,

\\ ( http://arXiv.org/abs/physics/0609133 , 956kb)

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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/ ========================================================================= 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 Tue Sep 19 2006 - 15:17:34 EST

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