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

Date: Sat, 13 Oct 2007 22:58:09 +1000 (EST)

Date: Sat, 13 Oct 2007 22:58:09 +1000 (EST)

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

Hi all,

There were 33 new preprints and 11 replacements for this week.

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arXiv:0709.2187

Date: Thu, 13 Sep 2007 23:50:18 GMT (311kb)

Title: Manipulating atoms in an optical lattice: Fractional fermion number and

its optical quantum measurement

Authors: J. Ruostekoski, J. Javanainen, G. V. Dunne

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

Comments: 18 pages, 9 figures

\\

We provide a detailed analysis of our previously proposed scheme [Phys. Rev.

Lett. 88, 180401, (2002)] to engineer the profile of the hopping amplitudes for

atomic gases in a 1D optical lattice so that the particle number becomes

fractional. We consider a constructed system of a dilute two-species gas of

fermionic atoms where the two components are coupled via a coherent

electromagnetic field with a topologically nontrivial phase profile. We show

both analytically and numerically how the resulting atomic Hamiltonian in a

prepared dimerized optical lattice with a defect in the pattern of alternating

hopping amplitudes exhibits a fractional fermion number. In particular, in the

low-energy limit we demonstrate the equivalence of the atomic Hamiltonian to a

relativistic Dirac Hamiltonian describing fractionalization in quantum field

theory. Expanding on our earlier argument [Phys. Rev. Lett. 91, 150404 (2003)]

we show how the fractional eigenvalues of the particle number operator can be

detected via light scattering. In particular, we show how scattering of far-off

resonant light can convey information about the counting statistics of the

atoms in an optical lattice, including state-selective atom density profiles

and atom number fluctuations. Optical detection could provide a truly quantum

mechanical measurement of the particle number fractionalization in a dilute

atomic gas.

\\ ( http://arxiv.org/abs/0709.2187 , 311kb)

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arXiv:0709.2193

Date: Fri, 14 Sep 2007 01:05:57 GMT (998kb)

Title: Radially Symmetric Nonlinear States of Harmonically Trapped

Bose-Einstein Condensates

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

D. J. Frantzeskakis

Categories: cond-mat.other

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

\\

Starting from the spectrum of the radially symmetric quantum harmonic

oscillator in two dimensions, we create a large set of nonlinear solutions. The

relevant three principal branches, with $n_r=0,1$ and 2 radial nodes

respectively, are systematically continued as a function of the chemical

potential and their linear stability is analyzed in detail, in the absence as

well as in the presence of topological charge $m$, i.e., vorticity. It is found

that for repulsive interatomic interactions {\it only} the ground state is {\it

linearly stable} throughout the parameter range examined. Furthermore, this is

true for topological charges $m=0$ or $m=1$; solutions with higher topological

charge can be unstable even in that case. All higher excited states are found

to be unstable in a wide parametric regime. However, for the

focusing/attractive case the ground state with $n_r=0$ and $m=0$ can only be

stable for a sufficiently low number of atoms. Once again, excited states are

found to be generically unstable. For unstable profiles, the dynamical

evolution of the corresponding branches is also followed to monitor the

temporal development of the instability.

\\ ( http://arxiv.org/abs/0709.2193 , 998kb)

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arXiv:0709.2212

Date: Fri, 14 Sep 2007 06:30:22 GMT (122kb)

Title: Molecular Bose-Einstein condensation in a versatile low power crossed

dipole trap

Authors: J. Fuchs, G. J. Duffy, G. Veeravalli, P. Dyke, M. Bartenstein, C. J.

Vale, P. Hannaford and W. J. Rowlands

Categories: cond-mat.other

Comments: 12 pages, 6 figures, submitted to J. Phys. B

\\

We produce Bose-Einstein condensates of 6Li2 molecules in a low power (22 W)

crossed optical dipole trap. Fermionic 6Li atoms are collected in a

magneto-optical trap from a Zeeman slowed atomic beam, then loaded into the

optical dipole trap where they are evaporatively cooled to quantum degeneracy.

Our simplified system offers a high degree of flexibility in trapping geometry

for studying ultracold Fermi and Bose gases.

\\ ( http://arxiv.org/abs/0709.2212 , 122kb)

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arXiv:0709.2273

Date: Fri, 14 Sep 2007 12:18:49 GMT (307kb)

Title: Multi-component strongly attractive Fermi gas: a color superconductor in

a one-dimensional harmonic trap

Authors: Xia-Ji Liu, Hui Hu and Peter D. Drummond

Categories: cond-mat.supr-con cond-mat.stat-mech

Comments: 15 pages, 9 figures

\\

Recent advances in ultra-cold atomic Fermi gases make it possible to achieve

a fermionic superfluid with multiple spin components. In this context, any

mean-field description is expected to fail, owing to the presence of tightly

bound clusters or molecules that consist of more than two particles. Here we

present a detailed study of a strongly interacting multi-component Fermi gas in

a highly elongated or quasi-one-dimensional harmonic trap, which could be

readily obtained in experiment. By using the exact Bethe ansatz solution and a

local density approximation treatment of the harmonic trap, we investigate the

equation of state of the multi-component Fermi gas in both a homogeneous and

trapped environment, as well as the density profiles and low-energy collective

modes. The binding energy of multi-component bound clusters is also given. We

show that there is a peak in the collective mode frequency at the critical

density for a deconfining transition to a many-body state that is analogous to

the quark color superconductor state expected in neutron stars.

\\ ( http://arxiv.org/abs/0709.2273 , 307kb)

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arXiv:0709.1986

Date: Thu, 13 Sep 2007 03:50:11 GMT (18kb)

Title: Quantum walk and quantum phase transition in optical lattice

Authors: C. M. Chandrashekar and Raymond Laflamme

Categories: quant-ph cond-mat.other physics.atom-ph

Comments: 4 pages, 5 figures

\\

We show that the quantum walk and its properties can be exploited to

redistribute the ultra-cold atoms in optical lattice into desired density

profile and quadratically speed up the the process of quantum phase transition.

We show this by evolving the density profile with every step of quantum walk by

numerical integration, where the correlation during the evolution can be

theoretically studied. We also discuss, how this can be implemented in the

realistic physical situations.

\\ ( http://arxiv.org/abs/0709.1986 , 18kb)

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rXiv:0709.2237

Date: Fri, 14 Sep 2007 09:20:57 GMT (402kb)

Title: An efficient source of continuous variable polarisation entanglement

Authors: Ruifang Dong, Joel Heersink, Jun-ichi Yoshikawa, Oliver Gloeckl, Ulrik

L. Andersen, Gerd Leuchs

Categories: quant-ph

Comments: 13 pages, 5 figures

\\

We have experimentally demonstrated the efficient creation of highly

entangled bipartite continuous variable polarisation states. Exploiting an

optimised scheme for the production of squeezing using the Kerr non-linearity

of a glass fibre we generated polarisation squeezed pulses with a mean

classical excitation in S3. Polarisation entanglement was generated by

interfering two independent polarisation squeezed fields on a symmetric beam

splitter. The resultant beams exhibit strong quantum noise correlations in the

dark S1 - S2 polarisation plane. To verify entanglement generation, we

characterised the quantum correlations of the system for two different sets of

conjugate Stokes parameters. The quantum correlations along the squeezed and

the anti-squeezed Stokes parameters were observed to be -4.1 +/- 0.3 dB and

-2.6 +/- 0.3 dB below the shot noise level respectively. The degree of

correlations was found to depend critically on the beam splitting ratio of the

entangling beam splitter. Carrying out measurements on a different set of

conjugate Stokes parameters, correlations of -3.6 +/- 0.3 dB and -3.4 +/- 0.3

dB have been observed. This result is more robust against asymmetries in the

entangling beam splitter, even in the presence of excess noise.

\\ ( http://arxiv.org/abs/0709.2237 , 402kb)

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arXiv:0709.2280

Date: Fri, 14 Sep 2007 12:50:40 GMT (271kb)

Title: Raman-induced limits to efficient squeezing in optical fibers

Authors: Ruifang Dong, Joel Heersink, Joel F. Corney, Peter D. Drummond, Ulrik

L. Andersen and Gerd Leuchs

Categories: quant-ph

Comments: 3 pages, 3 figures

\\

We report new experiments on polarization squeezing using ultrashort photonic

pulses in a single pass of a birefringent fiber. We measure what is to our

knowledge a record squeezing of -6.8 +/- 0.3 dB in optical fibers which when

corrected for linear losses is -10.4 +/- 0.8 dB. The measured polarization

squeezing as a function of optical pulse energy, which spans a wide range from

3.5-178.8 pJ, shows a very good agreement with the quantum simulations and for

the first time we see the experimental proof that Raman effects limit and

reduce squeezing at high pulse energy.

\\ ( http://arxiv.org/abs/0709.2280 , 271kb)

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arXiv:0709.2374

Date: Fri, 14 Sep 2007 20:00:01 GMT (10kb)

Title: Correlations in an expanding gas of hard-core bosons

Authors: D. M. Gangardt, M. Pustilnik

Categories: cond-mat.stat-mech

\\

We consider a longitudinal expansion of a one-dimensional gas of hard-core

bosons suddenly released from a trap. We show that the broken translational

invariance in the initial state of the system is encoded in correlations

between the bosonic occupation numbers in the momentum space. The correlations

are protected by the integrability and exhibit no relaxation during the

expansion.

\\ ( http://arxiv.org/abs/0709.2374 , 10kb)

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arXiv:0709.2386

Date: Fri, 14 Sep 2007 20:54:04 GMT (128kb)

Title: The one-dimensional Bose-Fermi-Hubbard model in the heavy-fermion limit

Authors: A. Mering and M. Fleischhauer

Categories: cond-mat.other

Comments: 12 pages, 15 figures

\\

We study the phase diagram of the zero-temperature, one-dimensional

Bose-Fermi-Hubbard model for fixed fermion density in the limit of small

fermionic hopping. This model can be regarded as an instance of a disordered

Bose-Hubbard model with dichotomic values of the stochastic variables. Phase

boundaries between compressible, incompressible (Mott-insulating) and partially

compressible phases are derived analytically within a generalized

strong-coupling expansion and numerically using density matrix renormalization

group (DMRG) methods. We provide evidence that the partially compressible

phases correspond to glass phases with exponentially decaying first-order

correlations. Fluctuations within the respective incompressible phases are

determined using perturbation theory and are compared to DMRG results.

\\ ( http://arxiv.org/abs/0709.2386 , 128kb)

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arXiv:0709.2501

Date: Sun, 16 Sep 2007 16:34:23 GMT (29kb)

Title: Generalized vorticity in transitional quantum turbulence

Authors: A. Bershadskii

Categories: cond-mat.other

\\

Transition to condensate state in the degenerate gas of bosons is studied

using the Gross-Pitaevskii equation. It is shown that adiabatic invariance of

an enstrophy (mean squared vorticity) based on a generalized vorticity $curl

(|\psi^2|{\bf v})/|\psi^2|$, controls dynamics of the transitional turbulence

just before formation of the condensate with its tangles of quantized vortices

($|\psi^2|{\bf v}$ is the weighted velocity field defined on the macroscopic

wave function $\psi$). Scaling of the angle-averaged occupation number

spectrum, $N_k \sim k^{-1}$, has been obtained for the free developing

transitional turbulence for the weak nonlinear (and completely disordered)

initial conditions. Results of the three-dimensional numerical simulations have

been used to support the theoretical consideration.

\\ ( http://arxiv.org/abs/0709.2501 , 29kb)

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arXiv:0709.2530

Date: Mon, 17 Sep 2007 06:08:07 GMT (40kb)

Title: Three-boson problem at low energy and Implications for dilute

Bose-Einstein condensates

Authors: Shina Tan

Categories: cond-mat.stat-mech

Comments: 24 pages, no figure

\\

It is shown that the effective interaction strength of three bosons at small

collision energies can be extracted from their wave function at zero energy. An

asymptotic expansion of this wave function at large interparticle distances is

derived, from which is defined a quantity $D$ named three-body scattering

hypervolume, which is an analog of the two-body scattering length. Given any

finite-range interaction potentials, one can thus predict the effective

three-body force from a numerical solution of the Schr\"{o}dinger equation. In

this way the constant $D$ for hard-sphere bosons is computed, leading to the

complete result for the ground state energy per particle of a dilute

Bose-Einstein condensate (BEC) of hard spheres to order $\rho^2$, where $\rho$

is the number density. Effects of $D$ are also demonstrated in the three-body

energy in a finite box of size $L$, which is expanded to the order $L^{-7}$,

and in the three-body scattering amplitude in vacuum. Another key prediction is

that there is a violation of the effective field theory (EFT) in the condensate

fraction in dilute BECs, caused by short-range physics. EFT predictions for the

ground state energy and few-body scattering amplitudes, however, are

corroborated.

\\ ( http://arxiv.org/abs/0709.2530 , 40kb)

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arXiv:0709.2621

Date: Mon, 17 Sep 2007 16:15:31 GMT (16kb)

Title: BCS-BEC crossover in a random external potential

Authors: G. Orso

Categories: cond-mat.supr-con

Comments: 4 pages, 2 figures

\\

We investigate the ground state properties of a disordered superfluid Fermi

gas across the BCS-BEC (Bose Einstein condensate) crossover. We show that, for

weak disorder, both the depletion of the condensate fraction of pairs and the

normal fluid density exhibit a nonmonotonic behavior as a function of the

interaction parameter $1/k_Fa$, reaching their minimum value near unitarity. We

find that, moving away from the weak coupling BCS regime, Anderson's theorem

ceases to apply and the superfluid order parameter is more and more affected by

the random potential.

\\ ( http://arxiv.org/abs/0709.2621 , 16kb)

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arXiv:0709.2653

Date: Mon, 17 Sep 2007 14:39:45 GMT (506kb)

Title: Quantum Fluctuations in the Superfluid State of the BCS-BEC Crossover

Authors: Roberto B. Diener, Rajdeep Sensarma, Mohit Randeria

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

Comments: 23 pages, 11 figures

\\

We determine the effects of quantum fluctuations about the T=0 mean field

solution of the BCS-BEC crossover in a dilute Fermi gas using the functional

integral method. These fluctuations are described in terms of the zero point

motion of collective modes and the virtual scattering of gapped quasiparticles.

We calculate their effects on various measurable properties, including chemical

potential, ground state energy, the gap, the speed of sound and the Landau

critical velocity. At unitarity, we find excellent agreement with quantum Monte

Carlo and experimental results. In the BCS limit, we show analytically that we

obtain Fermi liquid interaction corrections to thermodynamics including the

Hartree shift. In the BEC limit, we show that the theory leads to an

approximate description of the reduction of the scattering length for bosonic

molecules and also obtain quantum depletion of the Lee-Yang form. At the end of

the paper, we describe a method to include feedback of quantum fluctuations

into the gap equation, and discuss the problems of self-consistent calculations

in satisfying Goldstone's theorem and obtaining ultraviolet finite results at

unitarity.

\\ ( http://arxiv.org/abs/0709.2653 , 506kb)

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arXiv:0709.2425

Date: Sat, 15 Sep 2007 13:11:54 GMT (28kb)

Title: Detection of acceleration radiation in a Bose-Einstein condensate

Authors: A. Retzker, J. I. Cirac, M. B. Plenio, B. Reznik

Categories: quant-ph

Comments: 5 pages, 3 figures

\\

We propose and study methods for detecting the Unruh effect in a

Bose-Einstein condensate. The Bogoliubov vacuum of a Bose-Einstein condensate

is used here to simulate a scalar field-theory, and accelerated atom dots or

optical lattices as means for detecting phonon radiation due to acceleration

effects. We study Unruh's effect for linear acceleration and circular

acceleration. In particular, we study the dispersive effects of the Bogoliubov

spectrum on the ideal case of exact thermalization. Our results suggest that

Unruh's acceleration radiation can be tested using current accessible

experimental methods.

\\ ( http://arxiv.org/abs/0709.2425 , 28kb)

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arXiv:0709.2636

Date: Mon, 17 Sep 2007 13:51:28 GMT (178kb)

Title: Controlled deflection of a cold atomic cloud

Authors: Naceur Gaaloul (PPM, LSAMA), Laurence Pruvost (LAC), Mourad Telmini

(LSAMA), Eric Charron (PPM)

Categories: quant-ph

Proxy: ccsd hal-00172635

\\

We present a detailed, realistic proposal and analysis of the implementation

of a cold atom deflector using time-dependent far off-resonance optical guides.

An analytical model and numerical simulations are used to illustrate its

characteristics. We show that it is possible to deflect almost entirely a cloud

of $^{87}$Rb falling in the gravity field with angles reaching up to 25

degrees, using for all relevant parameters values that are achieved with

present technology. We discuss the limits of this proposed setup, and

illustrate its strong robustness against non-adiabatic transitions.

\\ ( http://arxiv.org/abs/0709.2636 , 178kb)

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arXiv:0709.2757

Date: Tue, 18 Sep 2007 15:44:52 GMT (15kb)

Title: Tkachenko modes in a superfluid Fermi gas at unitarity

Authors: Gentaro Watanabe, Marco Cozzini, and Sandro Stringari

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

Comments: 4 pages, 1 figure, submitted to PRA rapid communications

\\

We calculate the frequencies of the Tkachenko oscillations of a vortex

lattice in a harmonically trapped superfluid Fermi gas. We use the

elasto-hydrodynamic theory by properly accounting for the elastic constants,

the Thomas-Fermi density profile of the atomic cloud, and the boundary

conditions. Thanks to the Fermi pressure, which is responsible for larger cloud

radii with respect to the case of dilute Bose-Einstein condensed gases, large

vortex lattices are achievable in the unitary limit of infinite scattering

length, even at relatively small angular velocities. This opens the possibility

of experimentally observing vortex oscillations in the regime where the

dispersion relation approaches the Tkachenko law for incompressible fluids and

the mode frequency is almost comparable to the trapping frequencies.

\\ ( http://arxiv.org/abs/0709.2757 , 15kb)

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arXiv:0709.2747

Date: Tue, 18 Sep 2007 02:35:47 GMT (312kb)

Title: Spin squeezing and maximal-squeezing time

Authors: Guang-Ri Jin and Sang Wook Kim

Categories: quant-ph

Comments: 7 pages, 5 figures, 1 table. Resubmitted to Phys. Rev. A

\\

Spin squeezing of a nonlinear interaction model with Josephson-like coupling

is studied to obtain time scale of maximal squeezing. Based upon two exactly

solvable cases for two and three particles, we find that the maximal-squeezing

time depends on the level spacing between the ground state and its next

neighbor eigenstate.

\\ ( http://arxiv.org/abs/0709.2747 , 312kb)

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arXiv:0709.2749

Date: Tue, 18 Sep 2007 03:18:09 GMT (898kb)

Title: Single Atoms on an Optical Nanofiber

Authors: K. P. Nayak and K. Hakuta

Categories: quant-ph

Comments: 4 pages, 5 figures

\\

We show that single-atoms can be trapped on the surface of a

subwavelength-diameter silica-fiber, an optical nanofiber, without any external

field, and that single photons spontaneously emitted from the atoms can be

readily detected through the single guided-mode of the nanofiber. A key point

of the work is our finding that atom trapping sites are created on the

nanofiber surface by irradiating the atom cloud around the nanofiber with a

violet laser radiation.

\\ ( http://arxiv.org/abs/0709.2749 , 898kb)

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arXiv:0709.2849

Date: Tue, 18 Sep 2007 15:26:34 GMT (343kb)

Title: Trapped Rydberg Ions

Authors: I. Lesanovsky, L.-M. Liang, M. Mueller, and P. Zoller

Categories: quant-ph

Comments: 5 pages, 3 figures

\\

We study the quantum dynamics of trapped ions in Rydberg states, which have

large electric dipole moments induced by the trapping fields. In the limit

where the localization of the ion core is much smaller than the Rydberg orbit

the dynamics of the system is determined by the interplay between large

dipole-dipole energy shifts and strong tunable internal-state-dependent forces

due to dipole-charge interactions. This provides a new tool for manipulating

and entangling ions by strong interactions and on fast time scales.

\\ ( http://arxiv.org/abs/0709.2849 , 343kb)

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arXiv:0709.2866

Date: Tue, 18 Sep 2007 16:52:13 GMT (150kb)

Title: Bose-Einstein condensates with attractive 1/r interaction: The case of

self-trapping

Authors: I. Papadopoulos, P. Wagner, G. Wunner, J. Main

Categories: quant-ph

Comments: 7 pages, 7 figures, to appear in Phys. Rev. A

\\

Amplifying on a proposal by O'Dell et al. for the realization of

Bose-Einstein condensates of neutral atoms with attractive $1/r$ interaction,

we point out that the instance of self-trapping of the condensate, without

external trap potential, is physically best understood by introducing

appropriate "atomic" units. This reveals a remarkable scaling property: the

physics of the condensate depends only on the two parameters $N^2 a/a_u$ and

$\gamma/N^2$, where $N$ is the particle number, $a$ the scattering length,

$a_u$ the "Bohr" radius and $\gamma$ the trap frequency in atomic units. We

calculate accurate numerical results for self-trapping wave functions and

potentials, for energies, sizes and peak densities, and compare with previous

variational results. As a novel feature we point out the existence of a second

solution of the extended Gross-Pitaevskii equation for negative scattering

lengths, with and without trapping potential, which is born together with the

ground state in a tangent bifurcation. This indicates the existence of an

unstable collectively excited state of the condensate for negative scattering

lengths.

\\ ( http://arxiv.org/abs/0709.2866 , 150kb)

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arXiv:0709.2841

Date: Tue, 18 Sep 2007 14:56:09 GMT (288kb)

Title: Trapping and cooling of rf-dressed atoms in a quadrupole magnetic field

Authors: Olivier Morizot (LPL), Carlos L. Garrido Alzar (LPL), Paul-Eric Pottie

(LPL), Vincent Lorent (LPL), H\'el\`ene Perrin (LPL)

Categories: physics.atom-ph

Comments: 6 pages, 6 figures; to appear in J. Phys. B

Proxy: ccsd hal-00173059

\\

We observe the spontaneous evaporation of atoms confined in a bubble-like

rf-dressed trap (Zobay and Garraway, 2001). The atoms are confined in a

quadrupole magnetic trap and are dressed by a linearly polarized rf field. The

evaporation is related to the presence of holes in the trap, at the positions

where the rf coupling vanishes, due to its vectorial character. The final

temperature results from a competition between residual heating and evaporation

efficiency, which is controlled via the height of the holes with respect to the

bottom of the trap. The experimental data are modeled by a Monte-Carlo

simulation predicting a small increase in phase space density limited by the

heating rate. This increase was within the phase space density determination

uncertainty of the experiment.

\\ ( http://arxiv.org/abs/0709.2841 , 288kb)

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arXiv:0709.2934

Date: Tue, 18 Sep 2007 22:54:51 GMT (174kb)

Title: Quantum Hall Transition near a Fermion Feshbach Resonance in a Rotating

Trap

Authors: Kun Yang and Hui Zhai

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

Comments: 4 pages with one embedded figure

\\

We consider two-species of fermions in a rotating trap that interact via an

s-wave Feshbach resonance, at total Landau level filling factor two (or one for

each species). We show that the system undergoes a quantum phase transition

from a fermion integer quantum Hall state to a boson fractional quantum Hall

state as the pairing interaction strength increases, with the transition

occurring near the resonance. The effective field theory for the transition is

shown to be that of a (emergent) massless relativistic bosonic field coupled to

a Chern-Simons gauge field, with the coupling giving rise to semionic

statistics to the emergent particles.

\\ ( http://arxiv.org/abs/0709.2934 , 174kb)

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arXiv:0709.3017

Date: Wed, 19 Sep 2007 13:47:21 GMT (75kb)

Title: Emergent fermions and anyons in the Kitaev model

Authors: K. P. Schmidt, S. Dusuel, J. Vidal

Categories: cond-mat.other

Comments: 4 pages, 5 figures

\\

We study the gapped phase of the Kitaev model on the honeycomb lattice using

perturbative continuous unitary transformations. The effective low-energy

Hamiltonian is found to be an extended toric code with interacting anyons.

High-energy excitations are emerging free fermions which are composed of

hardcore bosons with an attached string of spin operators. The excitation

spectrum is mapped onto that of a single particle hopping on a square lattice

in a magnetic field. The present approach yields analytical perturbative

results in the thermodynamical limit and gives a simple description of the

spectrum without using the Majorana or the Jordan-Wigner fermionization

initially proposed to solve this problem.

\\ ( http://arxiv.org/abs/0709.3017 , 75kb)

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arXiv:0709.3027

Date: Wed, 19 Sep 2007 14:43:33 GMT (342kb,D)

Title: Phase diagram of a two-component Fermi gas with resonant interactions

Authors: Yong-il Shin, Christian H. Schunck, Andre Schirotzek, Wolfgang

Ketterle

Categories: cond-mat.soft

Comments: 8 pages, 8 figures

\\

The pairing of fermions is at the heart of superconductivity and

superfluidity. The recent experimental realization of strongly interacting

atomic Fermi gases has opened a new, controllable way to study novel forms of

pairing and superfluidity. A major controversial issue has been the stability

of superfluidity against an imbalance between the two spin components when the

fermions interact resonantly. Here we present the phase diagram of a

spin-polarized Fermi gas of 6Li atoms at unitarity, mapping out the superfluid

phases versus temperature and density imbalance. Using tomographic techniques,

we reveal spatial discontinuities in the spin polarization, the signature of a

first-order phase transition, which disappears at a tricritical point. These

observations and the implementation of an in situ ideal gas thermometer provide

a quantitative test of theoretical calculations on the stability of resonant

superfluidity.

\\ ( http://arxiv.org/abs/0709.3027 , 342kb)

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arXiv:0709.3050

Date: Wed, 19 Sep 2007 16:04:26 GMT (576kb)

Title: Coherent tunneling by adiabatic passage in an optical waveguide system

Authors: S. Longhi, G. Della Valle, M. Ornigotti, and P. Laporta

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

Comments: submitted for publication

\\

We report on the first experimental demonstration of light transfer in an

engineered triple-well optical waveguide structure which provides a classic

analogue of Coherent Tunnelling by Adiabatic Passage (CTAP) recently proposed

for coherent transport in space of neutral atoms or electrons among

tunneling-coupled optical traps or quantum wells [A.D. Greentree et al., Phys.

Rev. B 70, 235317 (2004); K. Eckert et al., Phys. Rev. A 70, 023606 (2004)].

The direct visualization of CTAP wavepacket dynamics enabled by our simple

optical system clearly shows that in the counterintuitive passage scheme light

waves tunnel between the two outer wells without appreciable excitation of the

middle well.

\\ ( http://arxiv.org/abs/0709.3050 , 576kb)

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arXiv:0709.3068

Date: Wed, 19 Sep 2007 16:53:22 GMT (935kb)

Title: Bose-Einstein Condensation of an Ytterbium Isotope

Authors: Takeshi Fukuhara, Seiji Sugawa, and Yoshiro Takahashi

Categories: cond-mat.other

Comments: 4 pages, 3 figures

\\

We report the observation of a Bose Einstein condensate in a bosonic isotope

of ytterbium (170Yb). More than 10^6 atoms are trapped in a crossed optical

dipole trap and cooled by evaporation. Condensates of approximately 10^4 atoms

have been obtained. From an expansion of the condensate, we have extracted the

scattering length a=3.6(9) nm.

\\ ( http://arxiv.org/abs/0709.3068 , 935kb)

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arXiv:0709.2996

Date: Wed, 19 Sep 2007 11:47:07 GMT (157kb,D)

Title: Entanglement-free Heisenberg-limited phase estimation

Authors: B. L. Higgins, D. W. Berry, S. D. Bartlett, H. M. Wiseman, G. J. Pryde

Categories: quant-ph

Comments: Accepted for publication in Nature. This is the original submitted

version, formatted 2-column

\\

Measurement underpins all quantitative science, and advances in precision

measurement have consistently led to new scientific discoveries. A key example

is the measurement of optical phase, used in length metrology and myriad other

applications. At the fundamental level, measurement precision is limited by the

number N of quantum resources (e.g. photons) that are used. Standard

measurement schemes, using each resource independently, lead to a phase

uncertainty scaling as 1/\sqrt{N} - the standard quantum limit (SQL). However,

it has long been conjectured that one should be able to achieve a precision

limited only by the Heisenberg uncertainty principle, dramatically improving

the scaling to 1/N . It is commonly held that to achieve this improvement

requires exotic states such as the "NOON" state. Unfortunately, the generation

of such states is extremely difficult - measurement schemes with counted

photons or ions have been performed with N <= 6, but few have surpassed the SQL

and none have shown Heisenberg-limited scaling. Here we perform the first

experimental demonstration of a Heisenberg-limited phase estimation procedure.

We replace entangled input states with multiple applications of the phase shift

on unentangled single-photon states. We generalize Kitaev's phase estimation

algorithm, using adaptive measurement theory, in order to achieve a standard

deviation scaling at the Heisenberg limit. For the largest number of resources

we use, N=378, we estimate an unknown phase with a variance more than 10 dB

below the SQL; achieving this variance would require more than 4,000 resources

using standard interferometry. Our results represent a drastic reduction in the

complexity of achieving quantum-enhanced measurement precision.

\\ ( http://arxiv.org/abs/0709.2996 , 157kb)

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rXiv:0709.3081

Date: Wed, 19 Sep 2007 17:59:09 GMT (18kb)

Title: Vibrational energy transfer in ultracold molecule - molecule collisions

Authors: Goulven Qu\'em\'ener, Naduvalath Balakrishnan, Roman V. Krems

Categories: quant-ph

Comments: 4 pages, 4 figures

\\

We present a rigorous study of vibrational relaxation in p-H2 - p-H2

collisions at cold and ultracold temperatures and identify a novel mechanism of

vibrational energy transfer. If the colliding molecules are in different

rotational and vibrational levels, the vibrational energy may be transferred

between the molecules through an extremely efficient and state-selective

process involving simultaneous vibrational excitation and de-excitation. If the

molecules are indistinguishable, this process corresponds to transfer of

rotational energy from one vibrational state of the colliding molecules to

another.

\\ ( http://arxiv.org/abs/0709.3081 , 18kb)

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\\

arXiv:0709.2924

Date: Tue, 18 Sep 2007 21:52:27 GMT (54kb)

Title: Feshbach resonances in ultracold ^{6,7}Li + ^{23}Na atomic mixtures

Authors: Marko Gacesa, Philippe Pellegrini, and Robin C\^ot\'e

Categories: physics.atom-ph

Comments: 4 pages, 2 figures

\\

We report a theoretical study of Feshbach resonances in a mixture of

$^{6,7}$Li and $^{23}$Na atoms at ultralow temperatures, using new accurate

interaction potentials in a full quantum coupled-channel calculation. Feshbach

resonances in the initial collision open channel $^6$Li$(f=1/2, m_f=1/2) +

^{23}$Na$(f=1, m_f=1)$ are found to agree with previous measurements, leading

to the first precise determination of the singlet and triplet scattering

lengths for the $^{6,7}$Li$+^{23}$Na pairs. We predict additional Feshbach

resonances within experimentally attainable magnetic fields for other collision

channels. Corresponding loss rates are also calculated.

\\ ( http://arxiv.org/abs/0709.2924 , 54kb)

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\\

arXiv:0709.3137

Date: Thu, 20 Sep 2007 13:49:07 GMT (97kb)

Title: Observation of photon-assisted tunneling in optical lattices

Authors: C. Sias and H. Lignier and Y. P. Singh and A. Zenesini and D. Ciampini

and O. Morsch and E. Arimondo

Categories: cond-mat.soft

Comments: 5 pages, 3 figures

\\

We have observed tunneling suppression and photon-assisted tunneling of

Bose-Einstein condensates in an optical lattice subjected to a constant force

plus a sinusoidal shaking. For a sufficiently large constant force, the ground

energy levels of the lattice are shifted out of resonance and tunneling is

suppressed; when the shaking is switched on, the levels are coupled by

low-frequency photons and tunneling resumes. Our results agree well with

theoretical predictions and demonstrate the usefulness of optical lattices for

studying solid-state phenomena.

\\ ( http://arxiv.org/abs/0709.3137 , 97kb)

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\\

arXiv:0709.3158

Date: Thu, 20 Sep 2007 08:38:52 GMT (145kb,D)

Title: Twin peaks in rf spectra of Fermi gases at unitarity in the normal phase

Authors: P. Massignan, G. M. Bruun and H. T. C. Stoof

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

Comments: 4 pages, 5 figures

\\

We calculate the radio-frequency spectrum of balanced and imbalanced

ultracold Fermi gases in the normal phase at unitarity. For the homogeneous

case, we find that the spectrum always has a single peak even in the pseudogap

regime. We demonstrate that the double-peaked structures observed for

intermediate temperatures in recent experiments are due to the presence of the

trap, with the shifted peak coming from the center of the cloud where the gas

is in the pseudogap regime and the unshifted peak coming from the edge where

the gas is very dilute. The main experimental features observed above the

critical temperature in the recent experiment of Schunck et al. [Science 316,

867 (2007)] are recovered with no fitting parameters.

\\ ( http://arxiv.org/abs/0709.3158 , 145kb)

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\\

arXiv:0709.3163

Date: Thu, 20 Sep 2007 09:19:49 GMT (431kb)

Title: Few-boson dynamics in double wells: From single-atom to correlated-pair

tunneling

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

Categories: cond-mat.other

\\

We investigate few-boson tunneling in a one-dimensional double well, covering

the full crossover from weak interactions to the fermionization limit of strong

correlations. Based on exact quantum-dynamical calculations, it is found that

the tunneling dynamics of two atoms evolves from Rabi oscillations to

correlated pair tunneling as we increase the interaction strength. Near the

fermionization limit, fragmented-pair tunneling is observed and analyzed in

terms of the population imbalance and two-body correlations. For more atoms,

the tunneling dynamics near fermionization is shown to be sensitive to both

atom number and initial configuration.

\\ ( http://arxiv.org/abs/0709.3163 , 431kb)

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\\

arXiv:0709.3212

Date: Thu, 20 Sep 2007 12:23:41 GMT (556kb)

Title: Electrostatic trapping of metastable NH molecules

Authors: Steven Hoekstra, Markus Metsala, Peter C. Zieger, Ludwig Scharfenberg,

Joop J. Gilijamse, Gerard Meijer and Sebastiaan Y. T. van de Meerakker

Categories: physics.atom-ph physics.chem-ph

\\

We report on the Stark deceleration and electrostatic trapping of $^{14}$NH

($a ^1\Delta$) radicals. In the trap, the molecules are excited on the

spin-forbidden $A ^3\Pi \leftarrow a ^1\Delta$ transition and detected via

their subsequent fluorescence to the $X ^3\Sigma^-$ ground state. The 1/e

trapping time is 1.4 $\pm$ 0.1 s, from which a lower limit of 2.7 s for the

radiative lifetime of the $a ^1\Delta, v=0,J=2$ state is deduced. The spectral

profile of the molecules in the trapping field is measured to probe their

spatial distribution. Electrostatic trapping of metastable NH followed by

optical pumping of the trapped molecules to the electronic ground state is an

important step towards accumulation of these radicals in a magnetic trap.

\\ ( http://arxiv.org/abs/0709.3212 , 556kb)

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The replacements:

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\\

arXiv:0705.2015

replaced with revised version Fri, 14 Sep 2007 18:37:29 GMT (41kb)

Title: Dynamics of excitations in a one-dimensional Bose liquid

Authors: M. Khodas, M. Pustilnik, A. Kamenev, L.I. Glazman

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

Journal-ref: Phys. Rev. Lett. 99, 110405 (2007)

DOI: 10.1103/PhysRevLett.99.110405

\\ ( http://arxiv.org/abs/0705.2015 , 41kb)

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\\

arXiv:cond-mat/0701786

replaced with revised version Mon, 17 Sep 2007 05:38:15 GMT (69kb)

Title: Thermodynamics of a Trapped Unitary Fermi Gas

Authors: Aurel Bulgac, Joaquin E. Drut, Piotr Magierski

Categories: cond-mat.stat-mech nucl-th physics.atom-ph

Comments: 4 pages, 4 figures

\\ ( http://arxiv.org/abs/cond-mat/0701786 , 69kb)

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\\

arXiv:0705.2320

replaced with revised version Sun, 16 Sep 2007 10:38:35 GMT (8kb)

Title: The Localization Length of Stationary States in the Nonlinear

Schreodinger Equation

Authors: Alexander Iomin and Shmuel Fishman

Categories: cond-mat.dis-nn astro-ph nlin.CD

\\ ( http://arxiv.org/abs/0705.2320 , 8kb)

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\\

arXiv:physics/0607034

replaced with revised version Mon, 17 Sep 2007 07:21:12 GMT (279kb)

Title: A Radio-Frequency Atom Chip for Guiding Neutral Atoms

Authors: Xiaolin Li, Haichao Zhang, Bo Yan, Min Ke, Yuzhu Wang

Categories: physics.atom-ph

\\ ( http://arxiv.org/abs/physics/0607034 , 279kb)

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\\

arXiv:0704.2299

replaced with revised version Mon, 17 Sep 2007 08:43:11 GMT (424kb)

Title: One-dimensional Rydberg Gas in a Magnetoelectric Trap

Authors: Michael Mayle, Bernd Hezel, Igor Lesanovsky and Peter Schmelcher

Categories: physics.atom-ph

Comments: 4 pages, 2 figures

Journal-ref: Phys. Rev. Lett. 99, 113004 (2007)

DOI: 10.1103/PhysRevLett.99.113004

\\ ( http://arxiv.org/abs/0704.2299 , 424kb)

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\\

arXiv:math-ph/0611043 (*cross-listing*)

replaced with revised version Tue, 18 Sep 2007 19:41:25 GMT (20kb)

Title: Interacting Bose and Fermi gases in low dimensions and the Riemann

hypothesis

Authors: Andr\'e LeClair

Categories: math-ph cond-mat.stat-mech hep-th math.MP math.NT

Comments: version 3: additional appendix explains how the $\nu$ to $1-\nu$

duality of Riemann's $\zeta (\nu)$ follows from a special modular

transformation in a massless relativistic theory

\\ ( http://arxiv.org/abs/math-ph/0611043 , 20kb)

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\\

arXiv:0707.0792

replaced with revised version Tue, 18 Sep 2007 16:08:35 GMT (63kb)

Title: Theory of RF-spectroscopy of strongly interacting Fermions

Authors: M. Punk, W. Zwerger

Categories: cond-mat.other

Comments: revised version, 4 pages, 3 figures, RevTex4

\\ ( http://arxiv.org/abs/0707.0792 , 63kb)

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\\

arXiv:0707.3003

replaced with revised version Mon, 17 Sep 2007 23:17:04 GMT (553kb)

Title: Energy Dependence of Scattering Ground State Polar Molecules

Authors: Christopher Ticknor

Categories: physics.atom-ph

Comments: Accepted PRA, 10 pages, 5 figures

\\ ( http://arxiv.org/abs/0707.3003 , 553kb)

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rXiv:0704.3867

replaced with revised version Thu, 20 Sep 2007 07:22:10 GMT (213kb)

Title: Inhibited Feshbach Conversion of Atomic Fermions to Molecular Bosons due

to Particle Interactions

Authors: Jie Liu, Li-Bin Fu, Bin Liu, Shi-Ping Yang and Biao Wu

Categories: cond-mat.mes-hall

Comments: 5 pages, 4 figures

\\ ( http://arxiv.org/abs/0704.3867 , 213kb)

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\\

arXiv:0705.3956

replaced with revised version Thu, 20 Sep 2007 11:24:05 GMT (25kb)

Title: Boson Mott insulators at finite temperatures

Authors: Fabrice Gerbier (LKB - Lhomond)

Categories: cond-mat.other

Proxy: ccsd hal-00149582

Journal-ref: Physical Review Letters 99 (2007) 120405

DOI: 10.1103/PhysRevLett.99.120405

\\ ( http://arxiv.org/abs/0705.3956 , 25kb)

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\\

arXiv:0706.1170

replaced with revised version Thu, 20 Sep 2007 09:44:39 GMT (180kb)

Title: A lattice of microtraps for ultracold atoms based on patterned magnetic

films

Authors: R. Gerritsma, S. Whitlock, T. Fernholz, H. Schlatter, J. A. Luigjes,

J.-U. Thiele, J. B. Goedkoop and R. J. C. Spreeuw

Categories: physics.atom-ph

Comments: 7 pages, 7 figures

Journal-ref: Phys. Rev. A 76, 033408 (2007)

\\ ( http://arxiv.org/abs/0706.1170 , 180kb)

------------------------------------------------------------------------------

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 Sat Oct 13 2007 - 22:58:09 EST

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