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

Date: Wed, 25 Jul 2007 17:55:23 +1000 (EST)

Date: Wed, 25 Jul 2007 17:55:23 +1000 (EST)

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

Hi all,

There are 27 new preprint and 11 replacements for this week

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arXiv:0707.0870

Date: Thu, 5 Jul 2007 20:12:10 GMT (867kb)

Title: Two-Dimensional Dynamics of Ultracold Atoms in Optical Lattices

Authors: Michiel Snoek and Walter Hofstetter

Categories: cond-mat.other

Comments: 4 pages, 6 figures

\\

We analyze the dynamics of ultracold atoms in optical lattices induced by a

sudden shift of the underlying harmonic trapping potential. In order to study

the effect of strong interactions, dimensionality and lattice topology on

transport properties, we consider bosonic atoms with arbitrarily strong

repulsive interactions, on a two-dimensional square lattice and a hexagonal

lattice. On the square lattice we find insulating behavior for weakly

interacting atoms and slow relaxation for strong interactions, even when a Mott

plateau is present, which in one dimension blocks the dynamics. On the

hexagonal lattice the center of mass relaxes to the new equilibrium for any

interaction strength.

\\ ( http://arxiv.org/abs/0707.0870 , 867kb)

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arXiv:0707.0956

Date: Fri, 6 Jul 2007 12:23:45 GMT (83kb,D)

Title: Real-time path integral approach to nonequilibrium many-body quantum

system

Authors: Lothar M\"uhlbacher and Eran Rabani

Categories: cond-mat.mes-hall cond-mat.stat-mech

Comments: 5 pages, 2 figures

\\

A real-time path integral Monte Carlo approach is developed to study the

dynamics in a many-body quantum system until reaching a nonequilibrium

stationary state. The approach is based on augmenting an exact reduced equation

for the evolution of the system in the interaction picture which is amenable to

an efficient path integral (worldline) Monte Carlo approach. Results obtained

for a model of inelastic tunneling spectroscopy reveal the applicability of the

approach to a wide range of physically important regimes, including high

(classical) and low (quantum) temperatures, and weak (perturbative) and strong

electron-phonon couplings.

\\ ( http://arxiv.org/abs/0707.0956 , 83kb)

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arXiv:0707.0985

Date: Fri, 6 Jul 2007 14:53:40 GMT (22kb)

Title: Rotating molecules in optical lattices, alignment and monopole crystals

Authors: J.R. Holt and J.M.F. Gunn

Categories: cond-mat.other

Comments: 4 pages, 1 figure

\\

The recent progress towards production of near-ground state

quantum-degenerate molecules raises the issue of how such "small" molecules

behave in an optical lattice. In this Letter we show that the coupling of the

molecular orientation to the local electric field direction will provide

severalnew phenomena. In the case where the lasers forming different

crystallographic directions of the lattice are incoherent, the orientation of

the molecules is conserved (for L = 1) and a novel form of anisotropic

superfluidity can be expected. When the lasers are coherent, and the optical

lattice is such that the splitting of the rotational levels is large compared

to the centre of mass energies,an adiabaic description of the molecular

orientation is appropriate. This leads to geometric vector potentials,

pseudo-magnetic monopoles and a frustrated band structure with degenerate

minima.

\\ ( http://arxiv.org/abs/0707.0985 , 22kb)

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arXiv:0707.1016

Date: Fri, 6 Jul 2007 16:55:13 GMT (152kb)

Title: Spatial and spectral shape of inhomogeneous non-equilibrium

exciton-polariton condensates

Authors: M. Wouters, I. Carusotto, C. Ciuti

Categories: cond-mat.other

Comments: 5 pages, 3 figures

\\

We develop a mean-field theory of the spatial profile and the spectral

properties of polariton condensates in nonresonantly pumped semiconductor

microcavities in the strong coupling regime. Predictions are obtained for both

the continuous-wave and the pulsed excitation regimes and the specific

signatures of the non-equilibrium character of the condensation process are

pointed out. A striking sensitivity of the condensate shape on the optical pump

spot size is demonstrated by analytical and numerical calculations, in good

quantitative agreement with recent experimental observations.

\\ ( http://arxiv.org/abs/0707.1016 , 152kb)

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arXiv:math-ph/0601016 (*cross-listing*)

Date: Mon, 9 Jan 2006 01:59:04 GMT (179kb)

Title: Ground state properties of one-dimensional Bose-Fermi mixtures

Authors: Zi-Xiang Hu, Qiu-Lan Zhang and You-Quan Li

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

Journal-ref: J. Phys. A: Math. Gen. 39, 351 (2006)

\\

Bose-Fermi mixtures in one dimension are studied in detail on the basis of an

exact solution. Corresponding to three possible choices of the referecce state

in the quantum inverse scattering method, three sets of Bethe-ansatz equations

are derived explicitly. The features of the ground state and low-lying

excitations are investigated. The ground state phase diagram caused by the

external field and chemical potential is obtained.

\\ ( http://arxiv.org/abs/math-ph/0601016 , 179kb)

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arXiv:0707.0902

Date: Fri, 6 Jul 2007 04:58:18 GMT (7kb)

Title: Flow Representation of the Bose-Hubbard Hamiltonian : General Case

Authors: Kazuyuki Fujii (Yokohama City University) and Tatsuo Suzuki (Shibaura

Institute of Technology)

Categories: quant-ph

Comments: Latex ; 8 pages ; 1 figure

\\

In this paper the explicit flow representation to the Bose-Hubbard

Hamiltonian is given in the general case. This representation may be useful in

creating cat states for the system of atoms trapped in the optical ring.

\\ ( http://arxiv.org/abs/0707.0902 , 7kb)

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arXiv:0707.0981

Date: Fri, 6 Jul 2007 14:38:20 GMT (884kb)

Title: Boson Pairs in a One-dimensional Split Trap

Authors: D.S. Murphy, J.F. McCann, J. Goold, Th. Busch

Categories: quant-ph

Comments: 9 pages, 8 figures

\\

We describe the properties of a pair of ultracold bosonic atoms in a

one-dimensional harmonic trapping potential with a tunable zero-ranged barrier

at the trap centre. The full characterisation of the ground state is done by

calculating the reduced single-particle density, the momentum distribution and

the two-particle entanglement. We derive several analytical expressions in the

limit of infinite repulsion (Tonks-Girardeau limit) and extend the treatment to

finite interparticle interactions by numerical solution. As pair interactions

in double wells form a fundamental building block for many-body systems in

periodic potentials, our results have implications for a wide range of

problems.

\\ ( http://arxiv.org/abs/0707.0981 , 884kb)

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arXiv:0707.1006

Date: Fri, 6 Jul 2007 16:08:56 GMT (147kb,D)

Title: The manifestation of quantum resonances and antiresonances in a finite

temperature dilute atomic gas

Authors: M. Saunders, P. L. Halkyard, K. J. Challis, S. A. Gardiner

Categories: physics.atom-ph

Comments: 15 pages, 7 figures

\\

We investigate the effect of temperature on resonant and antiresonant

dynamics in a dilute atomic gas kicked periodically by a standing wave laser

field. Our numerical calculations are based on a Monte Carlo method for an

incoherent mixture of non-interacting plane waves, and show that the atomic

dynamics are highly sensitive to the initial momentum width of the gas. We

explain this sensitivity by examining the time evolution of individual atomic

centre of mass momentum eigenstates with varying quasimomentum, and we have

determined analytic expressions for the evolution of the second-order momentum

moment to illustrate the range of behaviours.

\\ ( http://arxiv.org/abs/0707.1006 , 147kb)

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arXiv:0707.1205

Date: Mon, 9 Jul 2007 19:43:59 GMT (388kb)

Title: Non-Equilibrium Dynamics and Superfluid Ring Excitations in Binary

Bose-Einstein Condensates

Authors: K.M. Mertes, J. Merrill, R. Carretero-Gonzalez, D.J. Frantzeskakis,

P.G. Kevrekidis, and D.S. Hall

Categories: cond-mat.other

Comments: 4 pages, 3 figures (low res.), submitted to PRL

\\

We revisit a classic study [D. S. Hall {\it et al.}, Phys. Rev. Lett. {\bf

81}, 1539 (1998)] of interpenetrating Bose-Einstein condensates in the

hyperfine states $\ket{F = 1, m_f = -1}\equiv\ket{1}$ and $\ket{F = 2, m_f =

+1}\equiv\ket{2}$ of ${}^{87}$Rb and observe striking new non-equilibrium

component separation dynamics in the form of oscillating ring-like structures.

The process of component separation is not significantly damped, a finding that

also contrasts sharply with earlier experimental work, allowing a clean first

look at a collective excitation of a binary superfluid. We further demonstrate

extraordinary quantitative agreement between theoretical and experimental

results using a multi-component mean-field model with key additional features:

the inclusion of atomic losses and the careful characterization of trap

potentials (at the level of a fraction of a percent).

\\ ( http://arxiv.org/abs/0707.1205 , 388kb)

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arXiv:0707.1233

Date: Mon, 9 Jul 2007 12:05:44 GMT (691kb)

Title: Condensate and superfluid fractions for varying interactions and

temperature

Authors: V.I. Yukalov and E.P. Yukalova

Categories: cond-mat.stat-mech

Comments: Latex file, 22 pages, 5 figures

Journal-ref: Phys. Rev. A 76 (2007) 013602-9

\\

A system with Bose-Einstein condensate is considered in the frame of the

self-consistent mean-field approximation, which is conserving, gapless, and

applicable for arbitrary interaction strengths and temperatures. The main

attention is paid to the thorough analysis of the condensate and superfluid

fractions in a wide region of interaction strengths and for all temperatures

between zero and the critical point T_c. The normal and anomalous averages are

shown to be of the same order for almost all interactions and temperatures,

except the close vicinity of T_c. But even in the vicinity of the critical

temperature, the anomalous average cannot be neglected, since only in the

presence of the latter the phase transition at T_c becomes of second order, as

it should be. Increasing temperature influences the condensate and superfluid

fractions in a similar way, by diminishing them. But their behavior with

respect to the interaction strength is very different. For all temperatures,

the superfluid fraction is larger than the condensate fraction. These coincide

only at T_c or under zero interactions. For asymptotically strong interactions,

the condensate is almost completely depleted, even at low temperatures, while

the superfluid fraction can be close to one.

\\ ( http://arxiv.org/abs/0707.1233 , 691kb)

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arXiv:0707.1302

Date: Mon, 9 Jul 2007 16:52:41 GMT (361kb)

Title: Possibility of supersolid with repulsive fermions in an anisotropic

optical lattice near a Feshbach resonance

Authors: B. Wang and L.-M. Duan

Categories: cond-mat.other cond-mat.str-el

Comments: 4 pages with 3 figures

\\

We present numerical analysis of ground state properties of the

one-dimensional general Hubbard model (GHM) with particle assisted tunnelling

rates and repulsive interaction, which describes fermionic atoms in an

anisotropic optical lattice near a wide Feshbach resonance. Our calculation

uses the time evolving block decimation algorithm, which is an extension of the

density matrix renormalization group and provides a well controlled method for

one-dimensional systems. We show the repulsive GHM, when hole doped from

half-filling, shows up a phase with coexistence of quasi-long-range superfluid

and charge-density-wave orders, suggesting the possibility of a supersolid.

This feature is different from the property of the conventional Hubbard model,

indicting the particle assisted tunnelling in the GHM could bring in

qualitatively new physics.

\\ ( http://arxiv.org/abs/0707.1302 , 361kb)

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arXiv:0707.1319

Date: Mon, 9 Jul 2007 18:44:11 GMT (33kb)

Title: Quantum Monte Carlo simulations of bosonic and fermionic impurities in a

two-dimensional hard-core boson system

Authors: Anders. W. Sandvik

Categories: cond-mat.other

Comments: 4 pages, 5 figures

\\

A two-dimensional lattice hard-core boson system with a small fraction of

bosonic or fermionic impurity particles is studied. The impurities have the

same hopping and interactions as the dominant bosons and their effects are

solely due to quantum statistics. Quantum Monte Carlo simulations are carried

out in which paths of the dominant boson species are sampled and a summation is

performed over all second-species paths compatible with the permutation cycles.

Both kinds of impurities reduce modestly and equally the Kosterliz-Thouless

superfluid transition temperature. However, the effective impurity interactions

are found to be qualitatively different at lower temperatures; fermions are

repulsive and further suppress superfluidity at low temperatures.

\\ ( http://arxiv.org/abs/0707.1319 , 33kb)

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arXiv:0707.1011 (*cross-listing*)

Date: Fri, 6 Jul 2007 16:46:39 GMT (43kb)

Title: Statistical Phases and Momentum Spacings for One-Dimensional Anyons

Authors: Martin Greiter

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

Comments: 16 pages, 1 figure

\\

Anyons and fractional statistics are by now well established in

two-dimensional systems. In one dimension, fractional statistics has been

established so far only through Haldane's fractional exclusion principle, but

not via a fractional phase the wave function acquires as particles are

interchanged. At first sight, the topology of the configuration space appears

to preclude such phases in one dimension. Here we argue that the crossings of

one-dimensional anyons are always unidirectional, which makes it possible to

assign phases consistently and hence to introduce a statistical parameter

theta. The fractional statistics then manifests itself in fractional spacings

of the single-particle momenta of the anyons when periodic boundary conditions

are imposed. These spacings are given by Delta p = 2 pi hbar/L

(|theta|/pi+non-negative integer) for a system of length L. This condition is

the analogue of the quantisation of relative angular momenta according to

l_z=hbar(-theta/pi+2integer) for two-dimensional anyons.

\\ ( http://arxiv.org/abs/0707.1011 , 43kb)

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arXiv:0707.1178

Date: Mon, 9 Jul 2007 04:30:32 GMT (701kb,D)

Title: Characterization of EIT-based continuous variable quantum memories

Authors: G. H\'etet, A. Peng, M. T. Johnsson, J. J. Hope, P. K. Lam

Categories: quant-ph

\\

We present a quantum multi-modal treatment describing Electromagnetically

Induced Transparency (EIT) as a mechanism for storing continuous variablequantum

information in light fields. Taking into account the atomic noise

anddecoherences of realistic experiments, we model numerically the

propagation,storage, and readout of signals contained in the sideband amplitude

and phasequadratures of a light pulse. An analytical treatment of the effects

predictedby this more sophisticated model is then presented. Finally, we use

quantum

information benchmarks to examine the properties of the EIT-based memory and

show the parameters needed to operate beyond the quantum limit.

\\ ( http://arxiv.org/abs/0707.1178 , 701kb)

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arXiv:0707.1314

Date: Mon, 9 Jul 2007 19:54:49 GMT (187kb,D)

Title: Fluorescence during Doppler cooling of a single trapped atom

Authors: J. H. Wesenberg, R. J. Epstein, D. Leibfried, R. B. Blakestad, J.

Britton, J. P. Home, W. M. Itano, J. D. Jost, E. Knill, C. Langer, R. Ozeri,

S. Seidelin, D. J. Wineland

Categories: quant-ph

Comments: 12 pages, 11 figures, Submitted to Phys. Rev. A

\\

We investigate the temporal dynamics of Doppler cooling of an initially hot

single trapped atom in the weak binding regime using a semiclassical approach.

We develop an analytical model for the simplest case of a single vibrational

mode for a harmonic trap, and show how this model allows us to estimate the

initial energy of the trapped particle by observing the fluorescence rate

during the cooling process. The experimental implementation of this temperature

measurement provides a way to measure atom heating rates by observing the

temperature rise in the absence of cooling. This method is technically

relatively simple compared to conventiponal sideband detection methods, and the

two methods are in reasonable agreement. We also discuss the effects of RF

micromotion, relevant for a trapped atomic ion, and the effect of coupling

between the vibrational modes on the cooling dynamics.

\\ ( http://arxiv.org/abs/0707.1314 , 187kb)

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arXiv:0707.1357

Date: Tue, 10 Jul 2007 02:07:34 GMT (6kb)

Title: How to extract information about a nanosystem in canonical ensemble from

the larger system in grand canonical ensemble?

Authors: D. S. Kosov, M. F. Gelin and A.I. Vdovin

Categories: cond-mat.stat-mech

\\

We present a method to compute averages in canonical ensemble based on

calculations of the expectation values in grand canonical ensemble. The number

of particles n, which is fixed in the canonical ensemble, is not necessarily

the same as the average number of particles <N> in the grand canonical

ensemble.

\\ ( http://arxiv.org/abs/0707.1357 , 6kb)

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arXiv:0707.1446

Date: Tue, 10 Jul 2007 13:21:19 GMT (105kb)

Title: Excitations and superfluidity in non-equilibrium Bose-Einstein

condensates of exciton-polaritons

Authors: M. Wouters and I. Carusotto

Categories: cond-mat.mes-hall

Comments: 4 pages, 2 figures

\\

We present a generic model for the description of non-equilibrium

Bose-Einstein condensates, suited for the modelling of non-resonantly pumped

polariton condensates in a semiconductor microcavity. The excitation spectrum

and scattering of the non-equilibrium condensate with a defect are discussed.

\\ ( http://arxiv.org/abs/0707.1446 , 105kb)

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arXiv:0707.1465

Date: Tue, 10 Jul 2007 14:36:49 GMT (347kb)

Title: Resonant superradiant backward-scattering as a source for many-particle

entanglement

Authors: K.M.R. van der Stam, R. Meppelink, J.M. Vogels, J.W. Thomsen, and P.

van der Straten

Categories: cond-mat.other

Comments: 5 pages, 6 figures

\\

We investigate the atom pair production by superradiant backward-scattering

from a Bose-Einstein condensate. By driving the superradiant process with two

frequencies we can extend both the range of pulse duration and intensity by two

orders of magnitude and obtain full control over the number of scattered atoms

in forward and backward direction. We show that the atoms scattered in forward

direction are strongly correlated with the atoms scattered in backward

direction, which makes resonant superradiant backward-scattering a promising

candidate for many-particle entanglement.

\\ ( http://arxiv.org/abs/0707.1465 , 347kb)

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arXiv:0707.1520

Date: Wed, 11 Jul 2007 19:02:33 GMT (361kb)

Title: Shear viscosity of a superfluid Fermi gas in the unitarity limit

Authors: Gautam Rupak and Thomas Schaefer

Categories: cond-mat.other

Comments: 9 pages, 7 figures, LaTeX2e

\\

We compute the shear viscosity of a superfluid atomic Fermi gas in the

unitarity limit. The unitarity limit is characterized by a divergent scattering

length between the atoms, and it has been argued that this will result in a

very small viscosity. We show that in the low temperature T limit the shear

viscosity scales as xi^5/T^5, where the universal parameter 'xi' relates the

chemical potential and the Fermi energy, mu=xi E_F. Combined with the high

temperature expansions of the viscosity our results suggest that the viscosity

has a minimum near the critical temperature T_c. A naive extrapolation

indicates that the minimum value of the ratio of viscosity over entropy density

is within a factor of ~ 5 of the proposed lower bound hbar/(4\pi k_B).

\\ ( http://arxiv.org/abs/0707.1520 , 361kb)

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arXiv:0707.1538

Date: Tue, 10 Jul 2007 23:48:25 GMT (9kb)

Title: Transition temperature of the homogeneous, dilute and weakly interacting

Bose gas in D-dimensions

Authors: Sang-Hoon Kim

Categories: cond-mat.stat-mech

Comments: 4 pages, 1 figure

\\

The phase transition temperature of the homogeneous, dilute, and weakly

interacting Bose gas in D-dimensions ($2 < D \le 3$) is calculated by a mean

field method.

We show that when the shift of the leading order is $\Delta T_c/T_c^0 = c

\gam^{\al}$, c(D) is positive and $\al(D)=D/2-1$ in the short-wavelength range.

The T_c at D=2 is calculated in the same scheme. The result is compared with

others. The origin of the difference between \al=1/2 and the widely accepted

\al=1 in 3D is discussed.

\\ ( http://arxiv.org/abs/0707.1538 , 9kb)

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arXiv:0707.1649

Date: Wed, 11 Jul 2007 19:19:03 GMT (248kb)

Title: One-dimensional superfluid Bose-Fermi mixture: mixing, demixing and

bright solitons

Authors: Sadhan K. Adhikari and Luca Salasnich

Categories: cond-mat.other

Comments: 11 pages, 11 figures

\\

We study a ultra-cold and dilute superfluid Bose-Fermi mixture confined in a

strictly one-dimensional atomic waveguide by using a set of coupled nonlinear

mean-field equations obtained from the Lieb-Liniger energy density for bosons

and the Gaudin-Yang energy density for fermions. We consider a finite

Bose-Fermi inter-atomic strength $g_{bf}$ and both periodic and open boundary

conditions. We find that with periodic boundary conditions, i.e. in a quasi-1D

ring, a uniform Bose-Fermi mixture is stable only with a large fermionic

density. We predict that at small fermionic densities the ground state of the

system displays demixing if $g_{bf}>0$ and may become a localized Bose-Fermi

bright soliton for $g_{bf}<0$. Finally, we show, using variational and

numerical solution of the mean-field equations, that with open boundary

conditions, i.e. in a quasi-1D cylinder, the Bose-Fermi bright soliton is the

unique ground state of the system with a finite number of particles, which

could exhibit a partial mixing-demixing transition. In this case the bright

solitons are demonstrated to be dynamically stable. The experimental

realization of these Bose-Fermi bright solitons seems possible with present

setups.

\\ ( http://arxiv.org/abs/0707.1649 , 248kb)

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arXiv:0707.1568 (*cross-listing*)

Date: Wed, 11 Jul 2007 06:56:32 GMT (18kb)

Title: Rapidly Rotating Bose-Einstein Condensates in Homogeneous Traps

Authors: M. Correggi, T. Rindler-Daller, J. Yngvason

Categories: math-ph cond-mat.other math.MP

Comments: LaTex2e, 16 pages

MSC-class: 35Q55; 47J30; 76M23

\\

We extend the results of a previous paper on the Gross-Pitaevskii description

of rotating Bose-Einstein condensates in two-dimensional traps to confining

potentials of the form V(r) = r^s, $2<s <\infty$. Writing the coupling constant

as $1/\epsilon^2$ we study the limit $\epsilon \to 0$. We derive rigorously the

leading asymptotics of the ground state energy and the density profile when the

rotation velocity \Omega tends to infinity as a power of $1/\epsilon$. The case

of asymptotically homogeneous potentials is also discussed.

\\ ( http://arxiv.org/abs/0707.1568 , 18kb)

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arXiv:0707.1653

Date: Wed, 11 Jul 2007 16:00:38 GMT (79kb)

Title: Chaos in kicked Bose-Einstein condensates: Bogoliubov resonances

Authors: J. Reslen, C.E. Creffield, and T.S. Monteiro

Categories: quant-ph

Comments: 5 pages

\\

Bose-Einstein condensates (BECs) subject to short pulses (`kicks') from

standing waves of light represent a nonlinear analogue of the well-known chaos

paradigm, the quantum kicked rotor (QKR). We investigate condensate

instability, in the sense of exponential proliferation of non-condensate

particles, as a function of the kicking period and nonlinearity. We show that

Bogoliubov resonances play a key role in the onset of instability. For low kick

strengths they are isolated, and there is no single instability threshold: the

condensate loses, then recovers stability around a few isolated resonances. For

stronger kicks, multiple resonances contribute and we identify the BEC analogue

of the ``overlapping of resonances'' criterion of chaos, beyond which the

condensate is in general exponentially unstable. In addition to the standard

QKR, we study a more stable variant involving pairs of opposing kicks, and

compare and contrast their behavior. An analytical model for low-order

resonances, which accounts for their characteristic scaling properties, is

presented.

\\ ( http://arxiv.org/abs/0707.1653 , 79kb)

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arXiv:0707.1751

Date: Thu, 12 Jul 2007 10:08:14 GMT (491kb)

Title: Thermodynamics and superfluid density in BCS-BEC crossover with and

without population imbalance

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

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

Comments: 19 pages, 14 figures. Submitted to PRB

\\

We address the thermodynamics, density profiles and superfluid density of

trapped fermions undergoing BCS-BEC crossover, with and without population

imbalance. Our approach represents a fully consistent treatment of "pseudogap

effects", which reflect the distinction between the pair formation temperature

$T^*$ and the pair condensation temperature $T_c$ and must be accommodated by

modifying the fermionic excitation spectrum. This distinction has been omitted

from all other many body approaches in the literature. We show how enforcing

this corollary implies that pairing fluctuation contributions enter into both

the gap and the number equations; this is necessary in order to be consistent

with a generalized Ward identity. Furthermore, we demonstrate that we obtain

physical results for the superfluid density $n_s(T)$ at all $T$. In contrast,

previous work in the literature has led to ill-behaved $n_s(T)$. The superfluid

density is a critical measure of the physicality of a given crossover theory.

In order to properly address thermodynamic properties of a trapped Fermi gas,

it is necessary to demonstrate that the particle density profiles are

consistent with experiment. The lack of demonstrable consistency between

theoretical and experimental density profiles, along with problematic behavior

found for $n_s(T)$, casts doubt on previous claims in the literature concerning

quantitative agreement between thermodynamical calculations and experiment.

\\ ( http://arxiv.org/abs/0707.1751 , 491kb)

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arXiv:0707.1830

Date: Thu, 12 Jul 2007 16:12:57 GMT (258kb)

Title: Nonlinear transport of Bose-Einstein condensates through mesoscopic

waveguides

Authors: Tobias Paul, Michael Hartung, Klaus Richter, and Peter Schlagheck

Categories: cond-mat.other

Comments: 23 pages, 16 figures

\\

We study the coherent flow of interacting Bose-condensed atoms in mesoscopic

waveguide geometries. Analytical and numerical methods, based on the mean-field

description of the condensate, are developed to study both stationary as well

as time-dependent propagation processes. We apply these methods to the

propagation of a condensate through an atomic quantum dot in a waveguide,

discuss the nonlinear transmission spectrum and show that resonant transport is

generally suppressed due to an interaction-induced bistability phenomenon.

Finally, we establish a link between the nonlinear features of the transmission

spectrum and the self-consistent quasi-bound states of the quantum dot.

\\ ( http://arxiv.org/abs/0707.1830 , 258kb)

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arXiv:0707.1851

Date: Thu, 12 Jul 2007 18:21:20 GMT (8kb)

Title: Three comments on the Fermi gas at unitarity in a harmonic trap

Authors: D.T.Son

Categories: cond-mat.other

Comments: 6 pages, 1 figure

Report-no: INT-PUB 07-12

\\

In this note we consider three issues related to the unitary Fermi gas in a

harmonic trap. We present a short proof of a virial theorem, which states that

the average energy of a particle system at unitarity in a harmonic trap is

twice larger than the average potential energy. The theorem is valid for all

systems with no intrinsic scale, at zero or finite temperature. We discuss the

odd-even splitting in a unitarity Fermi gas in a harmonic trap. We show that at

large number of particles N the odd-even splitting is proportional to

N^{1/9}\hbar\omega, with an undetermined numerical constant. We also show that

for odd N the lowest excitation energies are of order N^{-1/3}\hbar\omega.

\\ ( http://arxiv.org/abs/0707.1851 , 8kb)

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arXiv:0707.1703

Date: Wed, 11 Jul 2007 20:38:46 GMT (357kb)

Title: Trapping of Neutral Rubidium with a Macroscopic Three-Phase Electric

Trap

Authors: T. Rieger, P. Windpassinger, S.A. Rangwala, G. Rempe, P.W.H. Pinkse

Categories: physics.atom-ph

Comments: 4 pages, 4 figures

\\

We trap neutral ground-state rubidium atoms in a macroscopic trap based on

purely electric fields. For this, three electrostatic field configurations are

alternated in a periodic manner. The rubidium is precooled in a magneto-optical

trap, transferred into a magnetic trap and then translated into the electric

trap. The electric trap consists of six rod-shaped electrodes in cubic

arrangement, giving ample optical access. Up to 10^5 atoms have been trapped

with an initial temperature of around 20 microkelvin in the three-phase

electric trap. The observations are in good agreement with detailed numerical

simulations.

\\ ( http://arxiv.org/abs/0707.1703 , 357kb)

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The replacements:

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arXiv:cond-mat/0610623

replaced with revised version Fri, 6 Jul 2007 14:12:25 GMT (31kb)

Title: A number-conserving approach to a minimal self-consistent treatment of

condensate and non-condensate dynamics in a degenerate Bose gas

Authors: S. A. Gardiner and S.A. Morgan

Categories: cond-mat.other

Comments: 20 pages. Equation (71) is corrected. An erratum will appear in Phys.

Rev. A

Journal-ref: Phys. Rev. A 75, 043621 (2007)

DOI: 10.1103/PhysRevA.75.043621

\\ ( http://arxiv.org/abs/cond-mat/0610623 , 31kb)

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arXiv:cond-mat/0507108

replaced with revised version Sat, 7 Jul 2007 03:20:18 GMT (603kb)

Title: Noise Correlations in one-dimensional systems of ultra-cold fermions

Authors: L.Mathey, E.Altman and A.Vishwanath

Categories: cond-mat.str-el cond-mat.other

Comments: 5 pages, 3 figures. Added discussion on the visibility of noise

correlation features for realistic conditions

\\ ( http://arxiv.org/abs/cond-mat/0507108 , 603kb)

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arXiv:quant-ph/0703199

replaced with revised version Mon, 9 Jul 2007 18:02:50 GMT (706kb)

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

atom chip: a proposal

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

and Jakob Reichel

Categories: quant-ph

Comments: 5 pages, 3 figures

\\ ( http://arxiv.org/abs/quant-ph/0703199 , 706kb)

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arXiv:quant-ph/0703157

replaced with revised version Mon, 9 Jul 2007 13:19:02 GMT (40kb)

Title: Cavity cooling of internal molecular motion

Authors: Giovanna Morigi, Pepijn W.H. Pinkse, Markus Kowalewski, and Regina de

Vivie-Riedle

Categories: quant-ph physics.atom-ph

Comments: 4 pages, 4 figures. To appear in Physical Review Letters

\\ ( http://arxiv.org/abs/quant-ph/0703157 , 40kb)

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arXiv:0706.4041

replaced with revised version Tue, 10 Jul 2007 13:51:58 GMT (963kb)

Title: Matter-wave Interferometry with Phase Fluctuating Bose-Einstein

Condensates

Authors: G.-B. Jo, J.-H. Choi, C.A. Christensen, Y.-R. Lee, T.A. Pasquini, W.

Ketterle, and D.E. Pritchard

Categories: cond-mat.other

Comments: 4 pages, 5 figures, figures corrected

\\ ( http://arxiv.org/abs/0706.4041 , 963kb)

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arXiv:cond-mat/0602108

replaced with revised version Tue, 10 Jul 2007 11:47:33 GMT (323kb)

Title: Supersonic optical tunnels for Bose-Einstein condensates

Authors: S. Wuester and B. J. Dabrowska-Wuester

Categories: cond-mat.other

Comments: 14 pages, 3 figures, published version

Journal-ref: New Journal of Physics, 9 (2007) 85

\\ ( http://arxiv.org/abs/cond-mat/0602108 , 323kb)

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arXiv:cond-mat/0609417

replaced with revised version Tue, 10 Jul 2007 12:19:40 GMT (48kb)

Title: Quantum depletion of collapsing Bose-Einstein condensates

Authors: S. Wuester, B. J. Dabrowska-Wuester, A. S. Bradley, M. J. Davis, P. B.

Blakie, J. J. Hope and C. M. Savage

Categories: cond-mat.other

Comments: 9 pages, 4 figures, replaced with published version

Journal-ref: Phys. Rev. A 75 (2007) 043611

\\ ( http://arxiv.org/abs/cond-mat/0609417 , 48kb)

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arXiv:cond-mat/0702045

replaced with revised version Tue, 10 Jul 2007 12:09:03 GMT (161kb)

Title: Limits to the analogue Hawking temperature in a Bose-Einstein condensate

Authors: S. Wuester and C.M. Savage

Categories: cond-mat.other

Comments: 9 pages, 4 figures, replaced with published version

Journal-ref: Phys. Rev. A 76 (2007) 013608

\\ ( http://arxiv.org/abs/cond-mat/0702045 , 161kb)

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arXiv:cond-mat/0703433

replaced with revised version Tue, 10 Jul 2007 16:42:32 GMT (34kb)

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

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

Categories: cond-mat.other

Comments: The expurgated version; accepted for publication in PRA

\\ ( http://arxiv.org/abs/cond-mat/0703433 , 34kb)

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arXiv:0707.0675

replaced with revised version Wed, 11 Jul 2007 14:35:57 GMT (265kb)

Title: Disorder-Induced Order in Two-Component Bose-Einstein Condensates

Authors: Armand Niederberger, Thomas Schulte, Jan Wehr, Maciej Lewenstein,

Laurent Sanchez-Palencia, Krzysztof Sacha

Categories: cond-mat.other cond-mat.dis-nn

Comments: 4 pages, 3 figures

\\ ( http://arxiv.org/abs/0707.0675 , 265kb)

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arXiv:0704.0912

replaced with revised version Tue, 10 Jul 2007 21:40:22 GMT (510kb)

Title: Nuclear Spin Effects in Optical Lattice Clocks

Authors: Martin M. Boyd, Tanya Zelevinsky, Andrew D. Ludlow, Sebastian Blatt,

Thomas Zanon-Willette, Seth M. Foreman and Jun Ye

Categories: physics.atom-ph

Comments: 13 pages, 12 figures, submitted to PRA

\\ ( http://arxiv.org/abs/0704.0912 , 510kb)

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arXiv:quant-ph/0609225 (*cross-listing*)

replaced with revised version Thu, 12 Jul 2007 03:34:30 GMT (820kb)

Title: Generating squeezing in an atom laser through self-interaction

Authors: Mattias T. Johnsson and Simon A. Haine

Categories: quant-ph cond-mat.other

Comments: v2. Incorporates changes due to referees' comments. We also

demonstrate that our scheme generates number squeezing as well as quadrature

squeezing

Journal-ref: Phys. Rev. Lett. 99, 010401 (2007)

\\ ( http://arxiv.org/abs/quant-ph/0609225 , 820kb)

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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 Wed Jul 25 2007 - 17:55:23 EST

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