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

Date: Thu, 29 Mar 2007 13:37:09 +1000 (EST)

Date: Thu, 29 Mar 2007 13:37:09 +1000 (EST)

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

Another late mailing this week :(

A total of 27 new papers and 15 replacements:

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Paper: cond-mat/0703433

Date: Fri, 16 Mar 2007 19:43:34 GMT (37kb)

Title: Spin-polarized Fermi superfluids as Bose-Fermi mixtures

Authors: E. Taylor, A. Griffin, and Y. Ohashi

Categories: cond-mat.other

Comments: 14 pages, 1 figure

Subj-class: Other

\\

In the strong-coupling BEC region where a Feshbach resonance gives rise to

tightly-bound dimer molecules, we show that a spin-polarized Fermi superfluid

reduces to a simple Bose-Fermi mixture of Bose-condensed dimers and the

leftover unpaired fermions. Using a many-body functional integral formalism,

the Gaussian fluctuations give rise to an induced dimer-dimer interaction

mediated by the unpaired fermions, with the dimer-fermion vertex being given by

the (mean-field) Born approximation. Treating the pairing fluctuations to

quartic order, we show how the action for a spin-polarized Fermi superfluid

reduces to one for a Bose-Fermi mixture at energies below the binding energy of

the dimers. This Bose-Fermi action includes an expression for the effective

dimer-unpaired fermion interaction in a spin-polarized Fermi superfluid beyond

the Born approximation, in the superfluid phase at finite temperatures. In the

low-density limit, we show how this dimer-fermion interaction gives the s-wave

scattering length $a_{BF}=1.18a_F$ ($a_F$ is the s-wave fermion scattering

length), a result first derived by Skorniakov and Ter-Martirosian in 1957 for

three interacting fermions.

\\ ( http://arXiv.org/abs/cond-mat/0703433 , 37kb)

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Paper: cond-mat/0703443

Date: Fri, 16 Mar 2007 16:33:19 GMT (150kb)

Title: Spectral properties of a Rydberg atom immersed in a Bose-Einstein

condensate

Authors: Stephan Middelkamp, Igor Lesanovsky, and P. Schmelcher

Categories: cond-mat.other

Subj-class: Other

\\

The electronic spectrum of a Rydberg atom immersed in a Bose-Einstein

condensate is investigated. The Heisenberg equations of motions for the

condensate and the Rydberg atom are derived. Neglecting the backaction of the

Rydberg atom onto the condensate decouples the equations describing the

condensate and Rydberg atom. In this case the spectral structure of the Rydberg

atom is completely determined by an effective potential which depends on the

density distribution of the condensate. We study the spectral properties for

the situation of an isotropic harmonic and anharmonic as well as axially

symmetric confinement. In the latter case an intriguing analogy with Rydberg

atoms in magnetic fields is encountered.

\\ ( http://arXiv.org/abs/cond-mat/0703443 , 150kb)

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Paper: cond-mat/0703449

Date: Fri, 16 Mar 2007 19:24:14 GMT (172kb)

Title: Open system of interacting fermions: Statistical properties of cross

sections and fluctuations

Authors: G.L.Celardo, F.M.Izrailev, V.G. Zelevinsky, G.P.Berman

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

Comments: 13 pages, 11 figures

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

\\

Statistical properties of cross sections are studied for an open system of

interacting fermions. The description is based on the effective non-Hermitian

Hamiltonian that accounts for the existence of open decay channels preserving

the unitarity of the scattering matrix. The intrinsic interaction is modelled

by the two-body random ensemble of variable strength. In particular, the

crossover region from isolated to overlapping resonances accompanied by the

effect of the width redistribution creating super-radiant and trapped states is

studied in detail. The important observables, such as average cross section,

its fluctuations, autocorrelation functions of the cross section and scattering

matrix, are very sensitive to the coupling of the intrinsic states to the

continuum around the crossover. A detailed comparison is made of our results

with standard predictions of statistical theory of cross sections, such as the

Hauser-Feshbach formula for the average cross section and Ericson theory of

fluctuations and correlations of cross sections. Strong deviations are found in

the crossover region, along with the dependence on intrinsic interactions and

degree of chaos inside the system.

\\ ( http://arXiv.org/abs/cond-mat/0703449 , 172kb)

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Paper (*cross-listing*): hep-ph/0703159

Date: Thu, 15 Mar 2007 07:58:06 GMT (71kb)

Title: BEC-BCS Crossover in the Nambu--Jona-Lasinio Model of QCD

Authors: Gaofeng Sun, Lianyi He and Pengfei Zhuang

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

Comments: 18 pages, 15 figures

Subj-class: High Energy Physics - Phenomenology; Superconductivity

\\

The BEC-BCS crossover in QCD at finite baryon and isospin chemical potentials

is investigated in the Nambu--Jona-Lasinio model. The diquark condensation in

two color QCD and the pion condensation in real QCD would undergo a BEC-BCS

crossover when the corresponding chemical potential increases. We determined

the crossover chemical potential as well as the BEC and BCS regions. The

crossover is not triggered by increasing the strength of attractive interaction

among quarks but driven by changing the charge density. The chiral symmetry

restoration at finite temperature and density plays an important role in the

BEC-BCS crossover. For real QCD, strong couplings in diquark and vector meson

channels can induce a diquark BEC-BCS crossover in color superconductor, and in

the BEC region the chromomagnetic instability is fully cured and the ground

state is a uniform phase.

\\ ( http://arXiv.org/abs/hep-ph/0703159 , 71kb)

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Paper (*cross-listing*): nlin.PS/0703032

Date: Thu, 15 Mar 2007 19:11:50 GMT (391kb)

Title: Solitary Waves Bifurcated from Bloch Band Edges in Two-dimensional

Periodic Media

Authors: Zuoqiang Shi, Jianke Yang

Categories: nlin.PS cond-mat.other physics.optics

Comments: 23 pages, 15 figures. To appear in Phys. Rev. E

Subj-class: Pattern Formation and Solitons; Optics; Other

\\

Solitary waves bifurcated from edges of Bloch bands in two-dimensional

periodic media are determined both analytically and numerically in the context

of a two-dimensional nonlinear Schr\"odinger equation with a periodic

potential. Using multi-scale perturbation methods, envelope equations of

solitary waves near Bloch bands are analytically derived. These envelope

equations reveal that solitary waves can bifurcate from edges of Bloch bands

under either focusing or defocusing nonlinearity, depending on the signs of

second-order dispersion coefficients at the edge points. Interestingly, at edge

points with two linearly independent Bloch modes, the envelope equations lead

to a host of solitary wave structures including reduced-symmetry solitons,

dipole-array solitons, vortex-cell solitons, and so on -- many of which have

never been reported before. It is also shown analytically that the centers of

envelope solutions can only be positioned at four possible locations at or

between potential peaks. Numerically, families of these solitary waves are

directly computed both near and far away from band edges. Near the band edges,

the numerical solutions spread over many lattice sites, and they fully agree

with the analytical solutions obtained from envelope equations. Far away from

the band edges, solitary waves are strongly localized with intensity and phase

profiles characteristic of individual families.

\\ ( http://arXiv.org/abs/nlin/0703032 , 391kb)

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Paper: quant-ph/0703148

Date: Fri, 16 Mar 2007 10:29:20 GMT (990kb)

Title: Kicked Bose-Hubbard systems and kicked tops -- destruction and

stimulation of tunneling

Authors: M P Strzys, E M Graefe and H J Korsch

Categories: quant-ph

\\

In the two-mode approximation Bose-Einstein condensates (BEC) in a

double-well potential can be described by a many particle Hamiltonian of

Bose-Hubbard type. We focus on such a BEC whose interatomic interaction

strength is modulated periodically with $\delta$-kicks. This System in fact

represents a model of a kicked top. The mean-field dynamics provide a rich

mixed phase space with regular and chaotic regions. By increasing the

kick-strength a bifurcation leads to the appearance of self-trapping states

localized in regular islands. This self-trapping is also found for the many

particle system, however in general suppressed by tunneling oscillations. We

show that the tunneling time can be calculated from the quasi-energy splitting

of the corresponding Floquet states. By varying the kick-strength these

quasi-energy levels undergo both avoided and even real crossings. Therefore

stimulation or actually complete destruction of tunneling is observed for this

many particle system.

\\ ( http://arXiv.org/abs/quant-ph/0703148 , 990kb)

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Paper: quant-ph/0703155

Date: Fri, 16 Mar 2007 15:56:07 GMT (228kb)

Title: Trapping cold atoms near carbon nanotubes: thermal spin flips and

Casimir-Polder potential

Authors: Rachele Fermani, Stefan Scheel, Peter L. Knight

Categories: quant-ph

Comments: 8 pages, 3 figures

\\

We investigate the possibility to trap ultracold atoms near the outside of a

metallic carbon nanotube (CN) which we imagine to use as a miniaturized

current-carrying wire. We calculate atomic spin flip lifetimes and compare the

strength of the Casimir-Polder potential with the magnetic trapping potential.

Our analysis indicates that the Casimir-Polder force is the dominant loss

mechanism and we compute the minimum distance to the carbon nanotube at which

an atom can be trapped.

\\ ( http://arXiv.org/abs/quant-ph/0703155 , 228kb)

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Paper: physics/0703168

Date: Fri, 16 Mar 2007 16:46:59 GMT (30kb)

Title: Effects of nonintegrability on stabilization of Feshbach molecules in

atom waveguides

Authors: V. A. Yurovsky

Categories: physics.atom-ph

Comments: 4 pages, 4 figures

Subj-class: Atomic Physics

\\

Deactivation of broad quasi-one-dimensional dibosonic molecules is analyzed.

Within integrable Lieb-Liniger-McGuire (LLMG) model an exact expression does

not demonstrate suppression of the deactivation at low collision energies.

Solution of Faddeev equations demonstrates that when a Feshbach resonance lifts

the symmetry of the LLMG model the deactivation becomes suppressed. This effect

shows a way for formation of a stable gas of dibosonic Feshbach molecules.

\\ ( http://arXiv.org/abs/physics/0703168 , 30kb)

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Paper: physics/0703172

Date: Fri, 16 Mar 2007 14:53:31 GMT (218kb)

Title: Implementation of a double-scanning technique for studies of the Hanle

effect in Rubidium vapor

Authors: A. Atvars, M. Auzinsh, E. A. Gazazyan, A. V. Papoyan, S. V. Shmavonyan

Categories: physics.atom-ph

Subj-class: Atomic Physics

\\

We have studied the resonance fluorescence of a room-temperature rubidium

vapor exited to the atomic 5P3/2 state (D2 line) by powerful single-frequency

cw laser radiation (1.25 W/cm^2) in the presence of a magnetic field. In these

studies, the slow, linear scanning of the laser frequency across the hyperfine

transitions of the D2 line is combined with a fast linear scanning of the

applied magnetic field, which allows us to record frequency-dependent Hanle

resonances from all the groups of hyperfine transitions including V- and Lambda

- type systems. Rate equations were used to simulate fluorescence signals for

85Rb due to circularly polarized exciting laser radiation with different mean

frequency values and laser intensity values. The simulation show a dependance

of the fluorescence on the magnetic field. The Doppler effect was taken into

account by averaging the calculated signals over different velocity groups.

Theoretical calculations give a width of the signal peak in good agreement with

experiment.

\\ ( http://arXiv.org/abs/physics/0703172 , 218kb)

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Paper: cond-mat/0703454

Date: Sat, 17 Mar 2007 01:41:48 GMT (268kb)

Title: Simulation and detection of Dirac fermions with cold atoms in an optical

lattice

Authors: Shi-Liang Zhu, Baigeng Wang, and L.-M. Duan

Categories: cond-mat.mtrl-sci

Comments: 4 pages

Subj-class: Materials Science

\\

We propose an experimental scheme to simulate and observe relativistic Dirac

fermions with cold atoms in a hexagonal optical lattice. By controlling the

lattice anisotropy, one can realize both massive and massless Dirac fermions

and observe the topological phase transition between them. Through explicit

calculations, we show that both the Bragg spectroscopy and the atomic density

profile in a trap can be used to demonstrate the Dirac fermions and the

associated phase transition.

\\ ( http://arXiv.org/abs/cond-mat/0703454 , 268kb)

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Paper: cond-mat/0703465

Date: Mon, 19 Mar 2007 14:34:25 GMT (501kb)

Title: Unitary Fermi gas in the epsilon expansion

Authors: Yusuke Nishida

Categories: cond-mat.other

Comments: 103 pages, 29 figures; PhD thesis submitted to Univ. of Tokyo

(supervisor: T. Hatsuda and D. T. Son)

Subj-class: Other

\\

We construct systematic expansions around four and two spatial dimensions for

a Fermi gas near the unitarity limit. Near four spatial dimensions such a Fermi

gas can be understood as a weakly-interacting system of fermionic and bosonic

degrees of freedom. To the leading and next-to-leading orders in the expansion

over \epsilon=4-d, with d being the dimensionality of space, we determine the

thermodynamic functions, the fermion quasiparticle spectrum, the critical

polarizations, and the critical temperature as functions of the binding energy

of the two-body state. We also show that the unitary Fermi gas near two spatial

dimensions reduces to a weakly-interacting Fermi gas and calculate the

thermodynamic functions and the fermion quasiparticle spectrum in the expansion

over \bar\epsilon=d-2. We discuss the matching of the two systematic expansions

around four and two spatial dimensions in order to extract physical observables

at d=3. We find good agreement of the results with those from recent Monte

Carlo simulations.

\\ ( http://arXiv.org/abs/cond-mat/0703465 , 501kb)

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Paper: cond-mat/0703475

Date: Mon, 19 Mar 2007 02:39:37 GMT (11kb)

Title: Knotted Solitons in a Charged Two-Condensate Bose System

Authors: Yi-Shi Duan, Xin-Hui Zhang, Yu-Xiao Liu and Li Zhao

Categories: cond-mat.supr-con

Comments: 12 pages,0 figures

Subj-class: Superconductivity

Journal-ref: PHYSICAL REVIEW B 74, 144508 (2006)

\\

By making use of the decomposition of U(1) gauge potential theory and the

\phi mapping method, we propose that a charged two-condensate Bose system

possesses vortex lines and two classes of knotted solitons. The topological

charges of the vortex lines are characterized by the Hopf indices and the

Brower degrees of \phi-mapping, and the knotted solitons are described by the

nontrivial Hopf invariant and the BF action, respectively.

\\ ( http://arXiv.org/abs/cond-mat/0703475 , 11kb)

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Paper: cond-mat/0703498

Date: Mon, 19 Mar 2007 19:44:04 GMT (239kb)

Title: Re-examining Bogoliubov's theory of an interacting Bose gas

Authors: A.M. Ettouhami

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

Comments: 17 pages, 7 figures

Subj-class: Statistical Mechanics; Other

\\

We point out a few questionable features of Bogoliubov's theory of an

interacting Bose gas. In this theory, one does not diagonalize the part

$\hat{H}_2$ of the Hamiltonian that is quadratic in the boson creation and

annihilation operators, but instead one diagonalizes the ``grand canonical

Hamiltonian" $\tilde{H}_2 = \hat{H}_2 - \mu \hat{N}_1$, where $\mu$ is the

chemical potential and the operator $\hat{N}_1$ counts the number of bosons

outside the condensate. We show that such a procedure leads to an energy cost

of exciting a single boson from the condensate to the single-particle state of

momentum ${\bf k}$ which diverges like $1/k$ in the long wavelength limit. We

also show that the above divergence does not occur if one diagonalizes

$\hat{H}_2$ directly, which results in a gapped excitation spectrum, both for

bosons and for quasiparticles. Gapped excitation spectra for bosons were

derived previously, by a number of authors, and were deemed unphysical on the

grounds that such spectra violate Goldstone's theorem. Here, we argue that such

an interpretation stems from an improper identification of the collective

Goldstone modes of the system, which have to do with fluctuations of the phase

of the condensate wavefunction. More importantly, we explicitly show that the

so-called "quasiparticle" modes of $\tilde{H}_2$ represent single-particle

excitations, {\em not} collective sound waves. Finally, we show that the

average interaction energy between condensed and depleted bosons is negative,

even for strictly repulsive interactions, which we argue seriously undermines

the validity of the present formulation of Bogoliubov's theory.

\\ ( http://arXiv.org/abs/cond-mat/0703498 , 239kb)

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Paper: quant-ph/0703156

Date: Fri, 16 Mar 2007 20:45:28 GMT (255kb)

Title: Deterministic loading of individual atoms to a high-finesse optical

cavity

Authors: Kevin M. Fortier, Soo Y. Kim, Michael J. Gibbons, Peyman Ahmadi, and

Michael S. Chapman

Categories: quant-ph

Comments: 10 pages, 5 figures, submitted to Phys. Rev. Lett

\\

Individual laser cooled atoms are delivered on demand from a single atom

magneto-optic trap to a high-finesse optical cavity using an atom conveyor.

Strong coupling of the atom with the cavity field allows simultaneous cooling

and detection of individual atoms for time scales exceeding 15 s. The single

atom scatter rate is studied as a function of probe-cavity detuning and probe

Rabi frequency, and the experimental results are in good agreement with

theoretical predictions. We demonstrate the ability to manipulate the position

of a single atom relative to the cavity mode with excellent control and

reproducibility.

\\ ( http://arXiv.org/abs/quant-ph/0703156 , 255kb)

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Paper: quant-ph/0703173

Date: Mon, 19 Mar 2007 14:50:21 GMT (92kb)

Title: Ultraslow propagation of matched pulses by four-wave mixing in an atomic

vapor

Authors: V. Boyer, C. F. McCormick, E. Arimondo, P. D. Lett

Categories: quant-ph

Comments: 5 pages, 4 figures

\\

We have observed the ultraslow propagation of matched pulses in nondegenerate

four-wave mixing in a hot atomic vapor. Probe pulses as short as 70 ns can be

delayed by a tunable time of up to 40 ns with little broadening or distortion.

During the propagation, a probe pulse is amplified and generates a conjugate

pulse which is faster and separates from the probe pulse before getting locked

to it at a fixed delay. The precise timing of this process allows us to

determine the key coefficients of the susceptibility tensor. The presence of

gain in this system makes this system very interesting in the context of

all-optical information processing.

\\ ( http://arXiv.org/abs/quant-ph/0703173 , 92kb)

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Paper: quant-ph/0703177

Date: Mon, 19 Mar 2007 17:58:20 GMT (89kb)

Title: Transport and Entanglement Generation in the Bose-Hubbard Model

Authors: O. Romero-Isart, K. Eckert, C. Rod\'o, and A. Sanpera

Categories: quant-ph

Comments: 14 pages, 6 figures

\\

We study entanglement generation via particle transport across a

one-dimensional system described by the Bose-Hubbard Hamiltonian. We analyze

how the competition between interactions and tunneling affects transport

properties and the creation of entanglement in the occupation number basis.

Alternatively, we propose to use spatially delocalized quantum bits, where a

quantum bit is defined by the presence of a particle either in a site or in the

adjacent one. Our results can serve as a guidance for future experiments to

characterize entanglement of ultracold gases in one-dimensional optical

lattices.

\\ ( http://arXiv.org/abs/quant-ph/0703177 , 89kb)

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Paper: quant-ph/0703178

Date: Mon, 19 Mar 2007 19:09:33 GMT (57kb)

Title: Quantum phases of interacting phonons in ion traps

Authors: X.-L. Deng, D. Porras and J.I. Cirac

Categories: quant-ph

Comments: 10 pages

\\

The vibrations of a chain of trapped ions can be considered, under suitable

experimental conditions, as an ensemble of interacting phonons, whose quantum

dynamics is governed by a Bose--Hubbard Hamiltonian. In this work we study the

quantum phases which appear in this system, and show that thermodynamical

properties, such as critical parameters and critical exponents, can be measured

in experiments with a limited number of ions. Besides that, interacting phonons

in trapped ions offer us the possibility to access regimes which are difficult

to study with ultracold bosons in optical lattices, like models with attractive

or site--dependent phonon-phonon interactions.

\\ ( http://arXiv.org/abs/quant-ph/0703178 , 57kb)

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Paper: cond-mat/0703500

Date: Mon, 19 Mar 2007 20:18:39 GMT (84kb)

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, 3 figures

Subj-class: Other

\\

We consider a trapped atomic system in the presence of spatially varying

laser fields. The laser-atom interaction leads to an effective spin-orbit

coupling for the fermions in the trap. Reflections of the fermions from the

trap boundaries provide a physical mechanism for effective momentum relaxation

and non-trivial (pseudo)-spin dynamics due to the emergent spin-orbit coupling.

We explicitly consider evolution of an initially spin-polarized Fermi gas in a

two-dimensional harmonic trap and derive exact non-equilibrium behavior of the

spin polarization. %which shows interesting dynamic features. In a symmetric

harmonic trap, the spin polarization shows periodic echoes with a frequency

equal to the harmonic trapping frequency. Perturbations, such as an asymmetry

of the trap, lead to the suppression of the spin echo amplitudes. We discuss a

possible experimental setup to observe spin relaxation and spin echoes and

provide numerical estimates for the relevant parameters.

\\ ( http://arXiv.org/abs/cond-mat/0703500 , 84kb)

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Paper: cond-mat/0703506

Date: Tue, 20 Mar 2007 05:02:38 GMT (168kb)

Title: Mott phases and quantum phase transitions of extended Bose-Hubbard

models in 2+1 dimensions

Authors: K. Sengupta

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

Comments: Mini review; conference proceeeding for STATPHYS - KOLKATA V; to be

published in Physica A

Subj-class: Strongly Correlated Electrons; Statistical Mechanics

\\

We review the recent theoretical developments towards understanding the Mott

phases and quantum phase transition of extended Bose-Hubbard models on lattices

in two spatial dimensions . We focuss on the description of these systems using

the dual vortex picture and point out the crucial role played by the geometry

of underlying lattices in determining the nature of both the Mott phases and

the quantum phase transitions. We also briefly compare the results of dual

vortex theory with quantum Monte Carlo results.

\\ ( http://arXiv.org/abs/cond-mat/0703506 , 168kb)

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Paper: cond-mat/0703508

Date: Tue, 20 Mar 2007 07:45:08 GMT (177kb)

Title: Spatial Coherence of a Polariton Condensate

Authors: Hui Deng, Glenn S. Solomon, Rudolf Hey, Klaus H. Ploog, Yoshihisa

Yamamoto

Categories: cond-mat.mes-hall

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\

We perform a Young's double-slit experiment to study the spatial coherence

properties of a two-dimensional Bose-Einstein condensate of semiconductor

microcavity polaritons. The coherence length of the system is measured as a

function of the pump rate, which confirms a spontaneous build-up of macroscopic

coherence at the BEC phase transition. An independent measurement reveals that

the position and momentum uncertainty product of the condensate is close to the

Heisenburg limit. An experimental realization of such a minimum uncertainty

wavepacket of the polariton condensate opens a door to coherent matter-wave

phenomena such as Josephson oscillation, superfluidity, and solitons in solid

state systems.

\\ ( http://arXiv.org/abs/cond-mat/0703508 , 177kb)

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Paper: cond-mat/0703523

Date: Tue, 20 Mar 2007 17:04:53 GMT (8kb)

Title: Vortex mass in a superfluid at low frequencies

Authors: D. J. Thouless and J. R. Anglin

Categories: cond-mat.other

Comments: 4 pages

Subj-class: Other

\\

An inertial mass of a vortex can be calculated by driving it round in a

circle with a steadily revolving pinning potential. We show that in the low

frequency limit this gives precisely the same formula that was used by Baym and

Chandler, but find that the result is not unique and depends on the force field

used to cause the acceleration. We apply this method to the Gross-Pitaevskii

model, and derive a simple formula for the vortex mass. We study both the long

range and short range properties of the solution. We agree with earlier results

that the non-zero compressibility leads to a divergent mass. From the

short-range behavior of the solution we find that the mass is sensitive to the

form of the pinning potential, and diverges logarithmically when the radius of

this potential tends to zero.

\\ ( http://arXiv.org/abs/cond-mat/0703523 , 8kb)

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Paper: cond-mat/0703526

Date: Tue, 20 Mar 2007 18:12:14 GMT (43kb)

Title: Local Density Functional Theory for Superfluid Fermionic Systems: The

Unitary Gas

Authors: Aurel Bulgac

Categories: cond-mat.supr-con

Comments: 4 pages, 4 eps figures

Subj-class: Superconductivity

\\

The first detailed comparison between ab initio calculations of finite

fermionic superfluid systems performed recently by S.Y. Chang and G.F. Bertsch

and the extension of the density functional theory Superfluid Local Density

Approximation (SLDA) is presented. It is shown that SLDA reproduces the total

energies, number density distributions in inhomogeneous systems along with the

energy of the normal state in homogeneous systems. Since in SLDA the effective

fermion mass differs from the bare fermion mass, the spectrum of elementary

excitations is also reproduced.

\\ ( http://arXiv.org/abs/cond-mat/0703526 , 43kb)

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Paper: quant-ph/0703185

Date: Tue, 20 Mar 2007 12:48:09 GMT (309kb)

Title: Addressing individual atoms in optical lattices with standing-wave

driving fields

Authors: Jaeyoon Cho

Categories: quant-ph

Comments: 4 pages, 3 figures

\\

A scheme for addressing individual atoms in one- or two-dimensional optical

lattices loaded with one atom per site is proposed. The scheme is based on

position-dependent atomic population transfer induced by several standing-wave

driving fields. This allows various operations important in quantum information

processing, such as manipulation and measurement of any single atom, two-qubit

operations between any pair of adjacent atoms, and patterned loading of the

lattice with one atom per every nth site for arbitrary n. The proposed scheme

is robust against considerable imperfections and actually within reach of

current technology.

\\ ( http://arXiv.org/abs/quant-ph/0703185 , 309kb)

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Paper: quant-ph/0703189

Date: Tue, 20 Mar 2007 18:55:24 GMT (84kb)

Title: Quantum synapse for cold atoms

Authors: G.A. Kouzaev

Categories: quant-ph

Comments: 3 figures

Journal-ref: 5th Int. Conf. Physics, Technology and Applications of Wave

processes, Samara, Russia,Sept. 2006

\\

In this paper, the quantum synaptic effect is studied that arisen in the

system of two crossed wires excited by the static (DC) and radio-frequency (RF)

currents. The potential barrier between the two orthogonal atom streams is

controlled electronically and the atoms can be transferred from one wire to

another under certain critical values of the RF and DC currents. The results

are interesting in the study of quantum interferometry and quantum registering

of cold atoms.

\\ ( http://arXiv.org/abs/quant-ph/0703189 , 84kb)

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Paper: physics/0703190

Date: Mon, 19 Mar 2007 21:43:52 GMT (21kb)

Title: Unitary Fermi Gas in a Harmonic Trap

Authors: S. Y. Chang, G. F. Bertsch

Categories: physics.atom-ph

Comments: 2 figures, 2 tables

Subj-class: Atomic Physics

\\

We present an {\it ab initio} calculation of small numbers of trapped,

strongly interacting fermions using the Green's Function Monte Carlo method

(GFMC). The ground state energy, density profile and pairing gap are calculated

for particle numbers $N = 2 \sim 22$ using the parameter-free "unitary"

interaction. Trial wave functions are taken of the form of correlated pairs in

a harmonic oscillator basis. We find that the lowest energies are obtained with

a minimum explicit pair correlation beyond that needed to exploit the

degeneracy of oscillator states. We find that energies can be well fitted by

the expression $a_{TF} E_{TF} + \Delta {\rm mod}(N,2)$ where $E_{TF}$ is the

Thomas-Fermi energy of a noninteracting gas in the trap and $\Delta$ is a

pairing gap. There is no evidence of a shell correction energy in the

systematics, but the density distributions show pronounced shell effects. We

find the value $\Delta= 0.7\pm 0.2\omega$ for the pairing gap. This is smaller

than the value found for the uniform gas at a density corresponding to the

central density of the trapped gas.

\\ ( http://arXiv.org/abs/physics/0703190 , 21kb)

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Paper: cond-mat/0204430

replaced with revised version Tue, 20 Mar 2007 20:49:51 GMT (9kb)

Title: Percolation transition in the Bose gas II

Authors: Andras Suto

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

Comments: The paper is completed with the proof of Eq. (34) and with a remark

after Eq. (44) on the existence for any m>ln(rho/rho_0) of an infinite cycle

which contains a fraction between exp{-(m+1)} and exp{-m} of the total number

of particles

Subj-class: Statistical Mechanics; Mathematical Physics

Journal-ref: J. Phys. A: Math. Gen. 35 (2002) 6995-7002

\\ ( http://arXiv.org/abs/cond-mat/0204430 , 9kb)

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\\

Paper: cond-mat/0703573

Date: Thu, 22 Mar 2007 09:17:36 GMT (273kb)

Title: Tunnelling couplings in discrete lattices, single particle band

structure and eigenstates of interacting atom pairs

Authors: Rune Piil and Klaus Molmer

Categories: cond-mat.other

Comments: 7 pages, 6 figures

Subj-class: Other

\\

By adjusting the tunnelling couplings over longer than nearest neighbor

distances it is possible in discrete lattice models to reproduce the properties

of the lowest energy band of a real, continuous periodic potential. We propose

to include such terms in problems with interacting particles and we show that

they have significant consequences for scattering and bound states of atom

pairs in periodic potentials.

\\ ( http://arXiv.org/abs/cond-mat/0703573 , 273kb)

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\\

Paper: cond-mat/0703585

Date: Thu, 22 Mar 2007 16:00:53 GMT (21kb)

Title: Temperature Dependence of Critical Number of Particles for Attracting

Atomic Bose Gas

Authors: Shyamal Biswas

Categories: cond-mat.stat-mech

Comments: 7 pages, 3 figures

Subj-class: Statistical Mechanics

\\

For an attractive two body interaction the collapse of the condensate in an

atomic Bose gas is experimentally observed if the number of atoms is greater

than a critical number. If the interaction is attractive, the density in the

central region of the trap tends to increase. This tendency is opposed by the

zero-point energy and by the thermal energy. If the number of atoms is greater

than a critical number, the central density increases very much and the

zero-point and thermal energy are no longer able to prevent the collapse of the

gas. We calculate the temperature dependence of the critical number particles

by a variational method within the Hartree-Fock approximation and find that

there is a dramatic increase in the critical number as the condensation point

is approached.

\\ ( http://arXiv.org/abs/cond-mat/0703585 , 21kb)

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\\

Paper: quant-ph/0703199

Date: Thu, 22 Mar 2007 18:13:52 GMT (453kb)

Title: A Bose-Einstein condensate coupled to a nanomechanical resonator on an

atom chip

Authors: Philipp Treutlein, David Hunger, Stephan Camerer, Theodor W. H\"ansch,

and Jakob Reichel

Categories: quant-ph

Comments: 5 pages, 3 figures

\\

We study the coupling of the spin of Bose-Einstein condensed atoms to the

mechanical oscillations of a nanoscale cantilever with a magnetic tip. This is

an experimentally viable hybrid quantum system which allows one to explore the

interface of quantum optics and condensed matter physics. We propose an

experiment where easily detectable atomic spin-flips are induced by the

cantilever motion. This can be used to probe thermal oscillations of the

cantilever with the atoms. At low cantilever temperatures, as realized in

recent experiments, back-action of the atoms onto the cantilever is significant

and the system represents a mechanical analog of cavity quantum

electrodynamics. With high but realistic cantilever quality factors, the strong

coupling regime can be reached, either with single atoms or collectively with

BECs. We discuss an implementation on an atom chip.

\\ ( http://arXiv.org/abs/quant-ph/0703199 , 453kb)

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The replacements:

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\\

Paper: cond-mat/0508669

replaced with revised version Fri, 16 Mar 2007 07:27:02 GMT (140kb)

Title: Classical Region of a Trapped Bose Gas

Authors: P. Blair Blakie and Matthew J. Davis

Categories: cond-mat.other

Comments: 6 pages, 5 figures; updated to include new results with interactions

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0508669 , 140kb)

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\\

Paper: cond-mat/0703282

replaced with revised version Fri, 16 Mar 2007 02:29:37 GMT (16kb)

Title: Temperature and scattering length dependent condensate fraction of

trapped Bose atoms

Authors: Sang-Hoon Kim

Categories: cond-mat.stat-mech

Comments: 3 pages, 4 figures

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0703282 , 16kb)

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\\

Paper: cond-mat/0204430

replaced with revised version Sun, 18 Mar 2007 15:51:02 GMT (9kb)

Title: Percolation transition in the Bose gas II

Authors: Andras Suto

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

Comments: The paper is completed with the proof of Eq. (34) and with a remark

after Eq. (44) on the existence for any m>ln(rho/rho_0) of an infinite cycle

which contains a fraction between exp{-(m+1)} and exp{-m} of the total number

of particles

Subj-class: Statistical Mechanics; Mathematical Physics

Journal-ref: J. Phys. A: Math. Gen. 35 (2002) 6995-7002

\\ ( http://arXiv.org/abs/cond-mat/0204430 , 9kb)

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\\

Paper: cond-mat/0510436

replaced with revised version Mon, 19 Mar 2007 19:58:44 GMT (31kb)

Title: A simple renormalization group approximation of the groundstate

properties of interacting bosonic systems

Authors: Roman Werpachowski and Jerzy Kijowski

Categories: cond-mat.stat-mech

Comments: RevTex 4, 10 figures (revised and updated)

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0510436 , 31kb)

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\\

Paper: cond-mat/0609059

replaced with revised version Sat, 17 Mar 2007 16:10:58 GMT (413kb)

Title: Anomalous Heat Conduction in a Quasi One-Dimensional Gases

Authors: Taka H. Nishino

Categories: cond-mat.stat-mech

Comments: 8 pages, 2 figures

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0609059 , 413kb)

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\\

Paper: cond-mat/0609169

replaced with revised version Mon, 19 Mar 2007 15:31:14 GMT (124kb)

Title: The new physics of non-equilibrium condensates: insights from classical

dynamics

Authors: P. R. Eastham

Categories: cond-mat.str-el cond-mat.mes-hall

Comments: 10 pages, 4 figures, submitted for a special issue of J. Phys.:

Condensed Matter on "Optical coherence and collective phenomena in

nanostructures". v2: added discussion of links to exact solutions

Subj-class: Strongly Correlated Electrons; Mesoscopic Systems and Quantum Hall

Effect

\\ ( http://arXiv.org/abs/cond-mat/0609169 , 124kb)

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\\

Paper: cond-mat/0612590

replaced with revised version Sat, 17 Mar 2007 10:44:58 GMT (104kb)

Title: Ground-State Fidelity and Bipartite Entanglement in the Bose-Hubbard

Model

Authors: Pierfrancesco Buonsante and Alessandro Vezzani

Categories: cond-mat.other quant-ph

Comments: 7 pages, 5 figures (endfloats used due to problems with figures and

latex. Sorry about that); final version, similar to the published one

Subj-class: Other

Journal-ref: Physical Review Letters 98, 11601 (2007)

DOI: 10.1103/PhysRevLett.98.110601

\\ ( http://arXiv.org/abs/cond-mat/0612590 , 104kb)

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\\

Paper: cond-mat/0703169

replaced with revised version Mon, 19 Mar 2007 19:11:37 GMT (235kb)

Title: Intrinsic Heating and Cooling in Adiabatic Processes for Bosons in

Optical Lattices

Authors: Tin-Lun Ho and Qi Zhou

Categories: cond-mat.other

Comments: 4 pages, 3 figures, misprints are corrected and an additional

acknowledgement is added

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0703169 , 235kb)

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\\

Paper: cond-mat/0602237

replaced with revised version Mon, 19 Mar 2007 20:16:39 GMT (130kb)

Title: Zero-temperature Kosterlitz-Thouless transition in a two-dimensional

quantum system

Authors: Claudio Castelnovo (1), Claudio Chamon (1), Christopher Mudry (2), and

Pierre Pujol (3). ((1) Boston University, (2) Paul Scherrer Institut, (3)

Ecole Normale Superieure)

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

Comments: (30 pages, 11 figures), v2 with minor corrections

Subj-class: Strongly Correlated Electrons; Statistical Mechanics

Journal-ref: Annals of Physics 322 (2007) 903-934

DOI: 10.1016/j.aop.2006.04.017

\\ ( http://arXiv.org/abs/cond-mat/0602237 , 130kb)

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\\

Paper: cond-mat/0611091

replaced with revised version Tue, 20 Mar 2007 11:13:02 GMT (242kb)

Title: Entanglement in extended Hubbard models and quantum phase transitions

Authors: Alberto Anfossi, Paolo Giorda, and Arianna Montorsi

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

Comments: 14 pages, 8 figures, 2 tables

Subj-class: Strongly Correlated Electrons; Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0611091 , 242kb)

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\\

Paper: quant-ph/0402152

replaced with revised version Tue, 20 Mar 2007 18:34:06 GMT (336kb)

Title: Collective effects in the dynamics of driven atoms in a high-Q resonator

Authors: Stefano Zippilli, Giovanna Morigi, Helmut Ritsch

Categories: quant-ph

Comments: 12 pages, 13 figures, significantly extended version, slightly

different from the published one

Journal-ref: Eur. Phys. J. D 31, 507 (2004)

\\ ( http://arXiv.org/abs/quant-ph/0402152 , 336kb)

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\\

Paper: quant-ph/0506030

replaced with revised version Tue, 20 Mar 2007 17:53:05 GMT (586kb)

Title: Cooling trapped atoms in optical resonators

Authors: Stefano Zippilli, Giovanna Morigi

Categories: quant-ph

Comments: 4 pages, 3 figures; version published in PRL

Journal-ref: Phys. Rev. Lett. 95, 143001 (2005)

\\ ( http://arXiv.org/abs/quant-ph/0506030 , 586kb)

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\\

Paper: cond-mat/0604164

replaced with revised version Wed, 21 Mar 2007 11:09:07 GMT (291kb)

Title: Fragmented superfluid due to frustration of cold atoms in optical

lattices

Authors: J. J. Garcia-Ripoll, J. Pachos

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

Comments: New version, more results, about 20 pages

Subj-class: Strongly Correlated Electrons

\\ ( http://arXiv.org/abs/cond-mat/0604164 , 291kb)

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\\

Paper: quant-ph/0508075

replaced with revised version Wed, 21 Mar 2007 11:33:41 GMT (894kb)

Title: Mechanical effects of optical resonators on driven trapped atoms: Ground

state cooling in a high finesse cavity

Authors: Stefano Zippilli, Giovanna Morigi

Categories: quant-ph

Comments: 17 pages, 6 figures

Journal-ref: Phys. Rev. A 72, 053408 (2005)

\\ ( http://arXiv.org/abs/quant-ph/0508075 , 894kb)

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\\

Paper: quant-ph/0611078

replaced with revised version Wed, 21 Mar 2007 19:13:15 GMT (86kb)

Title: Stability and entanglement in optical-atomic amplification of trapped

atoms: the role of atomic collisions

Authors: V. V. Fran\c{c}a and G. A. Prataviera

Categories: quant-ph

Comments: 6 pages, 4 figures, accepted by PRA

\\ ( http://arXiv.org/abs/quant-ph/0611078 , 86kb)

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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 Thu Mar 29 2007 - 13:37:09 EST

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