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

Date: Sat, 26 Jan 2008 13:08:37 +1000

Date: Sat, 26 Jan 2008 13:08:37 +1000

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

This week there were 31 new preprints and 6 replacements:

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arXiv:0801.0600

Date: Thu, 3 Jan 2008 21:12:14 GMT (898kb,D)

Title: Addressable, spin-dependent sub-wavelength optical lattices with cold

atoms

Authors: A. J. Daley, G. Pupillo, W. Yi, P. Zoller

Categories: cond-mat.other

Comments: 5 pages, 4 figures

\\

We discuss how adiabatic potentials can be used to create addressable

lattices on a subwavelength scale, which can be used as a tool for local

operations and readout within a lattice substructure, while taking advantage of

the faster timescales and higher energy and temperature scales determined by

the shorter lattice spacing. For Alkaline Earth atoms with non-zero nuclear

spin these potentials can be made state dependent, and we give specific

examples for Yb atoms.

\\ ( http://arxiv.org/abs/0801.0600 , 898kb)

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arXiv:0801.0635

Date: Fri, 4 Jan 2008 07:24:46 GMT (127kb)

Title: Phase separation and collapse in Bose-Fermi mixtures with a Feshbach

resonance

Authors: F. M. Marchetti, C. Mathy, M. M. Parish, D. A. Huse

Categories: cond-mat.other

Comments: 4+ pages, 2 figures

\\

We consider a mixture of single-component bosonic and fermionic atoms with an

interspecies interaction that is varied using a Feshbach resonance. By

performing a mean-field analysis of a two-channel model, which describes both

narrow and broad Feshbach resonances, we find an unexpectedly rich phase

diagram at zero temperature: Bose-condensed and non-Bose-condensed phases form

a variety of phase-separated states that are accompanied by both critical and

tricritical points. We discuss the implications of our results for the

experimentally observed collapse of Bose-Fermi mixtures on the attractive side

of the Feshbach resonance, and we make predictions for future experiments on

Bose-Fermi mixtures close to a Feshbach resonance.

\\ ( http://arxiv.org/abs/0801.0635 , 127kb)

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arXiv:0801.0636

Date: Fri, 4 Jan 2008 08:52:18 GMT (23kb)

Title: Fermions in Deep Optical Lattice under p-wave Feshbach Resonance

Authors: S.-K. Yip

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

Comments: 2 figures

\\

We investigate theoretically the energy levels of two identical Fermions in a

harmonic potential well under p-wave Feshbach resonance. The magnetic fields

needed to affect the energy levels differ strongly among the levels, and they

can be at values far from the free space resonant field.

\\ ( http://arxiv.org/abs/0801.0636 , 23kb)

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arXiv:0801.0656

Date: Fri, 4 Jan 2008 10:58:07 GMT (11kb)

Title: Thermal Lifshitz Force between Atom and Conductor with Small Density of

Carriers

Authors: L. P. Pitaevskii

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

Comments: 4 pages, 1 figure

\\

A new theory describing the interaction between atoms and a conductor with

small densities of current carriers is presented. The theory takes into account

the penetration of the static component of the thermally fluctuating field in

the conductor and generalizes the Lifshitz theory in the presence of a spatial

dispersion. The equation obtained for the force describes the continuous

crossover between the Lifshitz results for dielectrics and metals.

\\ ( http://arxiv.org/abs/0801.0656 , 11kb)

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arXiv:0801.0723

Date: Fri, 4 Jan 2008 19:45:45 GMT (105kb)

Title: Quantum criticality of U(1) gauge theories with fermionic and bosonic

matter in two spatial dimensions

Authors: Ribhu K. Kaul and Subir Sachdev

Categories: cond-mat.str-el

Comments: 30 pages, 8 figures

\\

We consider relativistic U(1) gauge theories in 2+1 dimensions, with N_b

species of complex bosons and N_f species of Dirac fermions at finite

temperature. The quantum phase transition between the Higgs and Coulomb phases

is described by a conformal field theory (CFT). At large N_b and N_f, but for

arbitrary values of the ratio N_b/N_f, we present computations of various

critical exponents and universal amplitudes for these CFTs. We make contact

with the different spin-liquids, charge-liquids and deconfined critical points

of quantum magnets that these field theories describe. We compute physical

observables that may be measured in experiments or numerical simulations of

insulating and doped quantum magnets.

\\ ( http://arxiv.org/abs/0801.0723 , 105kb)

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arXiv:0801.0427 (*cross-listing*)

Date: Wed, 2 Jan 2008 16:44:30 GMT (13kb)

Title: Vortices and Spontaneous Symmetry Breaking in Rotating Bose Gases

Authors: Robert Seiringer

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

Comments: Plenary talk given at QMath10, Moeciu, Romania, September 10-15, 2007

\\

We present a rigorous proof of the appearance of quantized vortices in dilute

trapped Bose gases with repulsive two-body interactions subject to rotation,

which was obtained recently in joint work with Elliott Lieb. Starting from the

many-body Schroedinger equation, we show that the ground state of such gases

is, in a suitable limit, well described by the nonlinear Gross-Pitaevskii

equation. In the case of axially symmetric traps, our results show that the

appearance of quantized vortices causes spontaneous symmetry breaking in the

ground state.

\\ ( http://arxiv.org/abs/0801.0427 , 13kb)

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arXiv:0801.0610

Date: Thu, 3 Jan 2008 22:37:50 GMT (15kb)

Title: Bounding the Bogoliubov coefficients

Authors: Petarpa Boonserm (Victoria University of Wellington) and Matt Visser

(Victoria University of Wellington)

Categories: quant-ph

Comments: 25 pages, plain LaTeX

\\

While over the last century or more considerable effort has been put into the

problem of finding approximate solutions for wave equations in general, and

quantum mechanical problems in particular, it appears that as yet relatively

little work seems to have been put into the complementary problem of

establishing rigourous bounds on the exact solutions. We have in mind either

bounds on parametric amplification and the related quantum phenomenon of

particle production (as encoded in the Bogoliubov coefficients), or bounds on

transmission and reflection coefficients. Modifying and streamlining an

approach developed by one of the present authors [Phys. Rev. A 59 (1999)

427-438], we investigate this question by developing a formal but exact

solution for the appropriate second-order linear ODE in terms of a time-ordered

exponential of 2x2 matrices, then relating the Bogoliubov coefficients to

certain invariants of this matrix. By bounding the matrix in an appropriate

manner, we can thereby bound the Bogoliubov coefficients.

\\ ( http://arxiv.org/abs/0801.0610 , 15kb)

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arXiv:0801.0623

Date: Fri, 4 Jan 2008 16:33:14 GMT (95kb)

Title: Double wells, scalar fields and quantum phase transitions in ions traps

Authors: A. Retzker, R. Thompson, D. Segal and M.B. Plenio

Categories: quant-ph

Comments: 6 pages, 5 figures

\\

Since Hund's work on the ammonia molecule, the double well potential has

formed a key paradigm in physics. Its importance is further underlined by the

central role it plays in the Landau theory of phase transitions. Recently, the

study of entanglement properties of many-body systems has added a new angle to

the study of quantum phase transitions of discrete and continuous degrees of

freedom, i.e., spin and harmonic chains. Here we show that control of the

radial degree of freedom of trapped ion chains allows for the simulation of

linear and non-linear Klein-Gordon fields on a lattice, in which the parameters

of the lattice, the non-linearity and mass can be controlled at will. The

system may be driven through a phase transition creating a double well

potential between different configurations of the ion crystal. The dynamics of

the system are controllable, local properties are measurable and tunnelling in

the double well potential would be observable.

\\ ( http://arxiv.org/abs/0801.0623 , 95kb)

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arXiv:0801.0624

Date: Fri, 4 Jan 2008 02:52:22 GMT (265kb)

Title: One dimensional lattice of permanent magnetic microtraps for ultracold

atoms on an atom chip

Authors: Mandip Singh, Michael Volk, Alexander Akulshin, Andrei Sidorov,

Russell McLean and Peter Hannaford

Categories: physics.atom-ph

Comments: 10 Pages, 6 Figures

\\

We report on the loading and trapping of ultracold atoms in a one dimensional

permanent magnetic lattice of period 10 micron produced on an atom chip. The

grooved structure which generates the magnetic lattice potential is fabricated

on a silicon substrate and coated with a perpendicularly magnetized

multilayered TbGdFeCo/Cr film of effective thickness 960 nm. Ultracold atoms

are evaporatively cooled in a Z-wire magnetic trap and then adiabatically

transferred to the magnetic lattice potential by applying an appropriate bias

field. Under our experimental conditions trap frequencies of up to 90 kHz in

the magnetic lattice are measured and the atoms are trapped at a distance of

less than 5 micron from the surface with a measured lifetime of about 450 ms.

These results are important in the context of studies of quantum coherence of

neutral atoms in periodic magnetic potentials on an atom chip.

\\ ( http://arxiv.org/abs/0801.0624 , 265kb)

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arXiv:0801.0744

Date: Fri, 4 Jan 2008 21:04:42 GMT (19kb)

Title: Resonating plaquette phases in large spin cold atom systems

Authors: Cenke Xu and Congjun Wu

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

Comments: 6 pages, 3 figures

\\

Large spin cold atom systems can exhibit novel magnetic properties which do

not appear in usual spin-1/2 systems. We investigate the SU(4) resonating

plaquette state in the three dimensional cubic optical lattice with spin-3/2

cold fermions. A novel gauge field formalism is constructed to describe the

Rokhsar-Kivelson type of Hamiltonian and a duality transformation is used to

study the phase diagram. Due to the proliferation of topological defects, the

system is generally gapped for the whole phase diagram of the quantum model,

which agrees with the recent numerical studies. A critical line is found for

the classical plaquette system, which also corresponds to a quantum many-body

wavefunction in a "plaquette liquid phase".

\\ ( http://arxiv.org/abs/0801.0744 , 19kb)

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arXiv:0801.0791

Date: Mon, 7 Jan 2008 05:06:14 GMT (26kb)

Title: Variational wavefunction study of the triangular lattice supersolid

Authors: Arnab Sen, Prasenjit Dutt, Kedar Damle, R. Moessner

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

Comments: 4 pages, 2-column PRL format

\\

We present a variational wavefunction which explains the behaviour of the

supersolid state formed by hard-core bosons on the triangular lattice. The

wavefunction is a linear superposition of {\em only and all} configurations

minimising the repulsion between the bosons (which it thus implements as a hard

constraint). Its properties can be evaluated exactly--in particular, the

variational minimisation of the energy yields (i) the surprising and initially

controversial spontaneous density deviation from half-filling (ii) a

quantitatively accurate estimate of the corresponding density wave (solid)

order parameter.

\\ ( http://arxiv.org/abs/0801.0791 , 26kb)

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arXiv:0801.0888

Date: Sun, 6 Jan 2008 20:38:11 GMT (50kb)

Title: Orbital orderings and frustrations of $p$-band systems in optical

lattices

Authors: Congjun Wu

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

\\

We investigate general structures of orbital exchange physics in the

Mott-insulating states of $p$-orbital systems in optical lattices. Various new

features of orderings and frustrations are analyzed in different lattices. In

particular, in the honeycomb lattice the $p$-orbital exchange physics is

described by a novel type quantum 120$^\circ$-model whose classical ground

states can be mapped into the fully packed loop model multiplied with a U(1)

degree of freedom. It exhibits strong orbital frustrations and is promising to

realize the orbital liquid state. Orbital exchanges and frustrations in the

$p$-orbital 3D cubic lattice are also discussed.

\\ ( http://arxiv.org/abs/0801.0888 , 50kb)

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arXiv:0801.0911

Date: Mon, 7 Jan 2008 07:25:39 GMT (61kb)

Title: Bold diagrammatic Monte Carlo: A generic technique for polaron (and

many-body?) problems

Authors: Nikolay Prokof'ev and Boris Svistunov

Categories: cond-mat.str-el

Comments: 15 pages, 15 figures, revtex4

\\

We develop a Monte Carlo scheme for sampling series of Feynman diagrams for

the proper self-energy which are self-consistently expressed in terms of

renormalized particle propagators. This approach is used to solve the problem

of a single spin-down fermion resonantly interacting with the Fermi gas of

spin-up particles. Though the original series based on bare propagators are

sign-alternating and divergent one can still determine the answer behind them

by using two strategies (separately or together): (i) using proper series

re-summation techniques, and (ii) introducing renormalized propagators which

are defined in terms of the simulated proper self-energy, i.e. making the

entire scheme self-consistent. Our solution is important for understanding the

phase diagram and properties of the BCS-BEC crossover in the strongly

imbalanced regime. On the technical side, we develop a generic sign-problem

tolerant method for exact numerical solution of polaron-type models, and,

possibly, of the interacting many-body Hamiltonians.

\\ ( http://arxiv.org/abs/0801.0911 , 61kb)

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arXiv:0801.0952

Date: Mon, 7 Jan 2008 11:59:11 GMT (70kb)

Title: Mott transition in bosonic systems: Insights from the variational

approach

Authors: Manuela Capello, Federico Becca, Michele Fabrizio, and Sandro Sorella

Categories: cond-mat.str-el

Comments: 12 pages and 19 figures. Related to arXiv:0705.2684

\\

We study the Mott transition occurring for bosonic Hubbard models in one,

two, and three spatial dimensions, by means of a variational wave function

benchmarked by Green's function Monte Carlo calculations. We show that a very

accurate variational wave function, constructed by applying a long-range

Jastrow factor to the non-interacting boson ground state, can describe the

superfluid-insulator transition in any dimensionality. Moreover, by mapping the

quantum averages over such a wave function into the the partition function of a

classical model, important insights into the insulating phase are uncovered.

Finally, the evidence in favor of anomalous scenarios for the Mott transition

in two dimensions are reported whenever additional long-range repulsive

interactions are added to the Hamiltonian.

\\ ( http://arxiv.org/abs/0801.0952 , 70kb)

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arXiv:0801.0966

Date: Mon, 7 Jan 2008 12:55:11 GMT (500kb)

Title: Universality of Many-Body States in Rotating Bose and Fermi Systems

Authors: M. Borgh, M. Koskinen, J. Christensson, M. Manninen, S. M. Reimann

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

Comments: 9 pages, 9 figures

\\

We propose a universal transformation from a many-boson state to a

corresponding many-fermion state in the lowest Landau level approximation of

rotating many-body systems, inspired by the Laughlin wave function and by the

Jain composite-fermion construction. We employ the exact-diagonalization

technique for finding the many-body states. The overlap between the transformed

boson ground state and the true fermion ground state is calculated in order to

measure the quality of the transformation. For very small and high angular

momenta, the overlap is typically above 90%. For intermediate angular momenta,

mixing between states complicates the picture and leads to small ground-state

overlaps at some angular momenta.

\\ ( http://arxiv.org/abs/0801.0966 , 500kb)

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arXiv:0801.1015

Date: Mon, 7 Jan 2008 16:08:40 GMT (316kb)

Title: Density-density correlations of the ultra-cold Fermi gas in an optical

lattice

Authors: T. Paananen, T. K. Koponen, P. T\"orm\"a, and J. -P. Martikainen

Categories: cond-mat.other

Comments: 24 pages, 10 figures

\\

In this paper we study the density-density correlations of the two component

Fermi gas in optical lattices. Three different type of phases, the BCS-state

(Bardeen, Cooper, and Schieffer), the FFLO-state (Fulde, Ferrel, Larkin, and

Ovchinnikov), and BP (breach pair) state, are considered. We show how these

states differ in their density-density correlations. The density-density

correlations are calculated not only at zero temperature, but also at non-zero

temperatures paying particular attention to how much the finite temperature

effects might complicate the detection of different phases. Since

one-dimensional systems have been shown to be very promising candidates to

observe FFLO states, we apply our results also to the computation of

correlation signals in a one-dimensional lattice. We find that the

density-density correlations reveal important information about the structure

of the underlying order parameter as well as about the quasiparticle

dispersions.

\\ ( http://arxiv.org/abs/0801.1015 , 316kb)

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arXiv:0801.1090

Date: Mon, 7 Jan 2008 18:16:13 GMT (574kb)

Title: Tunneling dynamics of few bosons in a double well

Authors: Sascha Z\"ollner, Hans-Dieter Meyer, Peter Schmelcher

Categories: cond-mat.other

Comments: 10 pages, 8 figures

\\

We study few-boson tunneling in a one-dimensional double well. As we pass

from weak interactions to the fermionization limit, the Rabi oscillations first

give way to highly delayed pair tunneling (for medium coupling), whereas for

very strong correlations multi-band Rabi oscillations emerge. All this is

explained on the basis of the exact few-body spectrum and without recourse to

the conventional two-mode approximation. Two-body correlations are found

essential to the understanding of the different tunnel mechanisms. The

investigation is complemented by discussing the effect of skewing the double

well, which offers the possibility to access specific tunnel resonances

\\ ( http://arxiv.org/abs/0801.1090 , 574kb)

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arXiv:0801.0724 (*cross-listing*)

Date: Fri, 4 Jan 2008 19:40:01 GMT (695kb)

Title: Emergent physics: Fermi point scenario

Authors: G.E. Volovik

Categories: gr-qc cond-mat.str-el hep-ph

Comments: 15 pages, 7 figures, extended and modified version of

arXiv:0709.1258, draft for proceedings of Royal Society scientific discussion

meeting "Cosmology meets condensed matter" to be held on 28 January 2008 in

London

\\

The Fermi-point scenario of emergent gravity has the following consequences:

gravity emerges together with fermionic and bosonic matter; emergent fermionic

matter consists of massless Weyl fermions; emergent bosonic matter consists of

gauge fields; Lorentz symmetry persists well above the Planck energy;

space-time is naturally 4-dimensional; Universe is naturally flat; cosmological

constant is naturally small or zero; underlying physics is based on discrete

symmetries; `quantum gravity' cannot be obtained by quantization of Einstein

equations; there is no contradiction between quantum mechanics and gravity;

etc.

\\ ( http://arxiv.org/abs/0801.0724 , 695kb)

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arXiv:0801.0881

Date: Sun, 6 Jan 2008 18:05:17 GMT (632kb)

Title: High-visibility multi-photon interference of Hanbury Brown - Twiss type

for classical light

Authors: I. N. Agafonov, M. V. Chekhova, T. Sh. Iskhakov, A. N. Penin

Categories: quant-ph

Comments: 11 pages, 9 figures

\\

Difference-phase (or Hanbury Brown - Twiss type) intensity interference of

classical light is considered in higher orders in the intensity. It is shown

that, while the visibility of sum-phase (NOON-type) interference for classical

sources drops with the order of interference, the visibility of

difference-phase interference has opposite behavior. For three-photon and

four-photon interference of two coherent sources, the visibility can be as high

as 81.8% and 94.4%, respectively. High-visibility three-photon and four-photon

interference of space-time and polarization types has been observed in

experiment, for both coherent and pseudo-thermal light.

\\ ( http://arxiv.org/abs/0801.0881 , 632kb)

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arXiv:0801.0932

Date: Mon, 7 Jan 2008 09:22:52 GMT (112kb)

Title: Optimum spin-squeezing in Bose-Einstein condensates with particle losses

Authors: Yun Li (LKB - Lhomond, ECNU), Yvan Castin (LKB - Lhomond), Alice

Sinatra (LKB - Lhomond)

Categories: quant-ph

Comments: 4 pages

Proxy: ccsd hal-00202464

\\

The problem of spin squeezing with a bimodal condensate in presence of

particle losses is solved analytically by the Monte Carlo wavefunction method.

We find the largest obtainable spin squeezing as a function of the one-body

loss rate, the two-body and three-body rate constants, and the s-wave

scattering length.

\\ ( http://arxiv.org/abs/0801.0932 , 112kb)

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arXiv:0801.0930

Date: Mon, 7 Jan 2008 09:16:44 GMT (25kb)

Title: Suppression of Nonlinear Interactions in Resonant Macroscopic Quantum

Devices : the Example of the Solid-State Ring Laser Gyroscope

Authors: Sylvain Schwartz (TRT), Fran\c{c}ois Gutty, Gilles Feugnet (TRT),

Philippe Bouyer (LCFIO), Jean-Paul Pocholle (TRT)

Categories: physics.optics

Proxy: ccsd hal-00202466

\\

We study the suppression of nonlinear interactions in resonant macroscopic

quantum devices in the case of the solid-state ring laser gyroscope. These

nonlinear interactions are tuned by vibrating the gain medium along the cavity

axis. Beat note occurrence under rotation provides a precise measurement of the

strength of nonlinear interactions, which turn out to vanish for some discrete

values of the amplitude of vibration. Our theoretical description, in very good

agreement with the measured data, suggests the use of a higher vibration

frequency to achieve quasi-ideal rotation sensing over a broad range of

rotation speeds. We finally underline the analogy between this device and some

other macroscopic quantum rotation sensors, such as ring-shaped superfluid

configurations, where nonlinear interactions could be tuned for example by the

use of magnetically-induced Feschbach resonance.

\\ ( http://arxiv.org/abs/0801.0930 , 25kb)

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arXiv:0801.1103

Date: Tue, 8 Jan 2008 01:01:51 GMT (123kb)

Title: Berry Phase Effect on Exciton Transport and Bose Einstein Condensate

Authors: Wang Yao, Qian Niu

Categories: cond-mat.mes-hall

Comments: 4 pages, 3 figures

\\

We show a gauge structure that naturally exists for excitons in

semiconductors. The resultant Berry phase effects on exciton center-of-mass

motion are discussed for long-lived spatially indirect excitons in coupled

quantum wells. Spin-dependent topological transport driven by mechanical and

statistical forces are predicted. For trapped exciton gas, the Berry phase

effect manifests as a spin-dependent revolving mechanism. When sufficiently

large number of excitons have condensed, a nonrotating Bose-Einstein condensate

may become unstable against vortex formation.

\\ ( http://arxiv.org/abs/0801.1103 , 123kb)

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arXiv:0801.1270

Date: Tue, 8 Jan 2008 16:26:51 GMT (674kb)

Title: Limits to the sensitivity of a low noise compact atomic gravimeter

Authors: J. Le Gou\"et (SYRTE), Tanja Mehlst\"aubler (PTB), Jaewan Kim,

S\'ebastien Merlet (SYRTE), Andre Clairon (SYRTE), Arnaud Landragin (SYRTE),

Franck Pereira Dos Santos (SYRTE)

Categories: physics.atom-ph

Comments: 30 pages, 14 figures

Proxy: ccsd hal-00203007

\\

A detailed analysis of the most relevant sources of phase noise in an atomic

interferometer is carried out, both theoretically and experimentally. Even a

short interrogation time of 100 ms allows our cold atom gravimeter to reach an

excellent short term sensitivity to acceleration of $1.4\times 10^{-8}$g at 1s.

This result relies on the combination of a low phase noise laser system,

efficient detection scheme and good shielding from vibrations. In particular,

we describe a simple and robust technique of vibration compensation, which is

based on correcting the interferometer signal by using the AC acceleration

signal measured by a low noise seismometer.

\\ ( http://arxiv.org/abs/0801.1270 , 674kb)

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arXiv:0801.1378

Date: Wed, 9 Jan 2008 09:25:32 GMT (609kb)

Title: Dressed matter waves

Authors: Andre Eckardt and Martin Holthaus

Categories: cond-mat.other

Comments: 9 pages, 4 figures, to be published in: J. Phys.: Conference Series

\\

We suggest to view ultracold atoms in a time-periodically shifted optical

lattice as a "dressed matter wave", analogous to a dressed atom in an

electromagnetic field. A possible effect lending support to this concept is a

transition of ultracold bosonic atoms from a superfluid to a Mott-insulating

state in response to appropriate "dressing" achieved through time-periodic

lattice modulation. In order to observe this effect in a laboratory experiment,

one has to identify conditions allowing for effectively adiabatic motion of a

many-body Floquet state.

\\ ( http://arxiv.org/abs/0801.1378 , 609kb)

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arXiv:0801.1387

Date: Wed, 9 Jan 2008 10:23:50 GMT (54kb)

Title: Stability of the homogeneous Bose-Einstein condensate at large gas

parameter

Authors: Abdulla Rakhimov, Chul Koo Kim, Sang-Hoon Kim, and Jae Hyung Yee

Categories: cond-mat.stat-mech

Comments: 9 pages, 3 figures, Revtex

\\

The properties of the uniform Bose gas is studied within the optimized

variational perturbation theory (Gaussian approximation) in a self-consistent

way. It is shown that the atomic BEC with a repulsive interaction becomes

unstable when the gas parameter gamma=rho a3 exceeds a critical value

gamma_{crit} ~ 0.01. The quantum corrections beyond the Bogoliubov-Popov

approximation to the energy density, chemical potential and pressure in powers

of gamma expansions are presented.

\\ ( http://arxiv.org/abs/0801.1387 , 54kb)

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arXiv:0801.1504

Date: Wed, 9 Jan 2008 20:58:39 GMT (313kb)

Title: Gap and Pseudogap of a Unitary Fermi Gas by Quantum Monte Carlo

Authors: A. Bulgac, J.E. Drut, P. Magierski, and G. Wlazlowski

Categories: cond-mat.stat-mech

Comments: 4 pages, 7 figures

\\

We present Monte Carlo calculations of the susceptibility of a homogeneous 3D

system of fermions in the unitary regime at finite temperatures. Our data

allows for the determination of the quasiparticle spectrum, which is accurately

parameterized by an effective mass, a mean field, and a gap, and we discuss the

temperature dependence of these parameters. These results show the presence of

a pseudogap for temperatures above the critical temperature, when the system

ceases to be superfluid. We also report on zero temperature extrapolations of

our data away from unitarity and we compare them with existing fixed-node

Quantum Monte Carlo calculations at zero temperature.

\\ ( http://arxiv.org/abs/0801.1504 , 313kb)

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arXiv:0801.0763 (*cross-listing*)

Date: Sat, 5 Jan 2008 00:05:20 GMT (446kb)

Title: The Energy of n Identical Bosons in a Finite Volume at O(L^{-7})

Authors: William Detmold and Martin J. Savage

Categories: hep-lat cond-mat.stat-mech nucl-th

Comments: 3 pages

Report-no: NT_at_UW-08-01

\\

The volume dependence of the ground-state energy of n identical bosons with

short-range interactions in a periodic spatial volume with sides of length L is

calculated at order L^{-7} in the large volume expansion. This result will

enable a refined determination of the pi^+ pi^+ pi^+ interaction from lattice

QCD calculations.

\\ ( http://arxiv.org/abs/0801.0763 , 446kb)

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arXiv:0801.1523

Date: Thu, 10 Jan 2008 18:58:12 GMT (270kb,D)

Title: Determination of the Equation of State of a Two-Component Fermi Gas at

Unitarity

Authors: Yong-il Shin

Categories: cond-mat.stat-mech

Comments: 4 pages, 3 figures

\\

We report on the measurement of the equation of state of a two-component

Fermi gas of $^6$Li atoms with resonant interactions. By analyzing the in situ

density distributions of a population-imbalanced Fermi mixture confined in a

harmonic trap, we determine the energy density of a resonantly interacting

Fermi gas as a function of the densities of the two components. The presence of

the non-interacting ideal Fermi gas in the outer region of the trapped sample

allows to measure the equation of state directly from the shape of the cloud

without any absolute calibration of particle density. From the density profiles

obtained at our lowest temperature, we estimate the zero-temperature equation

of state.

\\ ( http://arxiv.org/abs/0801.1523 , 270kb)

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arXiv:0801.1567

Date: Thu, 10 Jan 2008 09:36:23 GMT (140kb)

Title: Semifluxons in Superconductivity and Cold Atomic Gases

Authors: R. Walser, E. Goldobin, O. Crasser, D. Koelle, R. Kleiner and W. P.

Schleich

Categories: cond-mat.mes-hall cond-mat.supr-con

Comments: 15 pages (Latex), 6 color figures (eps)

\\

Josephson junctions and junction arrays are well studied devices in

superconductivity. With external magnetic fields one can modulate the phase in

a long junction and create traveling, solitonic waves of magnetic flux, called

fluxons. Today, it is also possible to device two different types of junctions:

depending on the sign of the critical current density, they are called 0- or

pi-junction. In turn, a 0-pi junction is formed by joining two of such

junctions. As a result, one obtains a pinned Josephson vortex of fractional

magnetic flux, at the 0-pi boundary. Here, we analyze this arrangement of

superconducting junctions in the context of an atomic bosonic quantum gas,

where two-state atoms in a double well trap are coupled in an analogous

fashion. There, an all-optical 0-pi Josephson junction is created by the phase

of a complex valued Rabi-frequency and we a derive a discrete four-mode model

for this situation, which qualitatively resembles a semifluxon.

\\ ( http://arxiv.org/abs/0801.1567 , 140kb)

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\\

arXiv:0801.1570

Date: Thu, 10 Jan 2008 09:54:07 GMT (433kb)

Title: Coherent Delocalization of Atomic Wave Packets in Driven Lattice

Potentials

Authors: V.V. Ivanov, A. Alberti, M. Schioppo, G. Ferrari, M. Artoni, M. L.

Chiofalo, and G. M. Tino

Categories: physics.atom-ph physics.optics

Comments: 4 pages

\\

Atomic wave packets loaded into a phase-modulated vertical optical-lattice

potential exhibit a coherent delocalization dynamics arising from intraband

transitions among Wannier-Stark levels. Wannier-Stark intraband transitions are

here observed by monitoring the in situ wave-packet extent. By varying the

modulation frequency, we find resonances at integer multiples of the Bloch

frequency. The resonances show a Fourier-limited width for interrogation times

up to 2 s. This can also be used to determine the gravity acceleration with ppm

resolution.

\\ ( http://arxiv.org/abs/0801.1570 , 433kb)

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\\

arXiv:0801.1580

Date: Thu, 10 Jan 2008 11:49:51 GMT (366kb)

Title: Determination of the Newtonian Gravitational Constant Using Atom

Interferometry

Authors: G. Lamporesi, A. Bertoldi, L. Cacciapuoti, M. Prevedelli and G.M. Tino

Categories: physics.atom-ph

Comments: 4 figures

\\

We present a new measurement of the Newtonian gravitational constant G based

on cold atom interferometry. Freely falling samples of laser-cooled rubidium

atoms are used in a gravity gradiometer to probe the field generated by nearby

source masses. In addition to its potential sensitivity, this method is

intriguing as gravity is explored by a quantum system. We report a value of

G=6.667 10^{-11} m^{3} kg^{-1} s^{-2}, estimating a statistical uncertainty of

$\pm$ 0.011 10^{-11} m^{3} kg^{-1} s^{-2} and a systematic uncertainty of $\pm$

0.003 10^{-11} m^{3} kg^{-1} s^{-2}. The long-term stability of the instrument

and the signal-to-noise ratio demonstrated here open interesting perspectives

for pushing the measurement accuracy below the 100 ppm level.

\\ ( http://arxiv.org/abs/0801.1580 , 366kb)

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The replacements:

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\\

arXiv:cond-mat/0612592

replaced with revised version Fri, 4 Jan 2008 11:46:15 GMT (33kb)

Title: Wigner Crystallization in Rapidly Rotating 2D Dipolar Fermi Gases

Authors: M.A. Baranov, H. Fehrmann, and M. Lewenstein

Categories: cond-mat.mes-hall

Comments: 5 pages, 3 figures

\\ ( http://arxiv.org/abs/cond-mat/0612592 , 33kb)

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\\

arXiv:0706.3378

replaced with revised version Fri, 4 Jan 2008 22:34:28 GMT (775kb)

Title: Many-body protected entanglement generation in interacting spin systems

Authors: A. M. Rey, L. Jiang, M. Fleischhauer, E. Demler and M.D. Lukin

Categories: cond-mat.other

Comments: 11 pages, 7 figures. This paper is a longer version of the paper

cond-mat/0703108

\\ ( http://arxiv.org/abs/0706.3378 , 775kb)

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\\

arXiv:0710.5099 (*cross-listing*)

replaced with revised version Mon, 7 Jan 2008 16:36:01 GMT (391kb)

Title: Creation of resilient entangled states and a resource for

measurement-based quantum computation with optical superlattices

Authors: B. Vaucher, A. Nunnenkamp, and D. Jaksch

Categories: cond-mat.other quant-ph

Comments: 23 pages, 6 figures, IOP style, to appear in New Journal of Physics

\\ ( http://arxiv.org/abs/0710.5099 , 391kb)

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\\

arXiv:cond-mat/0612133

replaced with revised version Tue, 8 Jan 2008 07:00:48 GMT (79kb)

Title: Density-density correlation and interference mechanism for two initially

independent Bose-Einstein condensates

Authors: Shujuan Liu, Hongwei Xiong

Categories: cond-mat.stat-mech

Comments: See also cond-mat/0612132 (or New Journal of Physics 8, 245 (2006))

Journal-ref: New J. Phys. 9, 412 (2007)

\\ ( http://arxiv.org/abs/cond-mat/0612133 , 79kb)

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\\

arXiv:0709.0817

replaced with revised version Tue, 8 Jan 2008 10:38:22 GMT (21kb)

Title: Competition between final-state and pairing-gap effects in the

radio-frequency spectra of ultracold Fermi atoms

Authors: A. Perali, P. Pieri, G.C. Strinati

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

Comments: 4 pages, 3 figures, final version published in Phys. Rev. Lett

Journal-ref: Phys. Rev. Lett. 100, 010402 (2008)

DOI: 10.1103/PhysRevLett.100.010402

\\ ( http://arxiv.org/abs/0709.0817 , 21kb)

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\\

arXiv:0712.1482

replaced with revised version Wed, 9 Jan 2008 08:15:25 GMT (701kb)

Title: Guided atom laser : a new tool for guided atom optics

Authors: J. Billy (LCFIO), V. Josse (LCFIO), Z. Zuo (LCFIO), W. Guerin (LCFIO,

Inln), A. Aspect (LCFIO), Philippe Bouyer (LCFIO)

Categories: cond-mat.other

Proxy: ccsd hal-00195321

\\ ( http://arxiv.org/abs/0712.1482 , 701kb)

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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 Fri Feb 01 2008 - 10:16:26 EST

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