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

Date: Wed, 18 Oct 2006 17:50:19 +1000 (EST)

Date: Wed, 18 Oct 2006 17:50:19 +1000 (EST)

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

Getting later in the week again.... 30 new listings this week.

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

The abstracts:

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Paper: cond-mat/0610187

Date: Fri, 6 Oct 2006 16:59:18 GMT (479kb)

Title: Vortex Formation by Interference of Multiple Trapped Bose-Einstein

Condensates

Authors: David R. Scherer, Chad N. Weiler, Tyler W. Neely, Brian P. Anderson

Comments: 5 pages, 3 figures

Subj-class: Other

\\

We report observations of vortex formation as a result of merging together

multiple $^{87}$Rb Bose-Einstein condensates (BECs) in a confining potential.

In this experiment, a trapping potential is partitioned into three sections by

a barrier, enabling the simultaneous formation of three independent,

uncorrelated condensates. The three condensates then merge together into one

BEC, either by removal of the barrier, or during the final stages of

evaporative cooling if the barrier energy is low enough; both processes can

naturally produce vortices within the trapped BEC. We interpret the vortex

formation mechanism as originating in interference between the initially

independent condensates, with indeterminate relative phases between the three

initial condensates and the condensate merging rate playing critical roles in

the probability of observing vortices in the final, single BEC.

\\ ( http://arXiv.org/abs/cond-mat/0610187 , 479kb)

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Paper: quant-ph/0610043

Date: Fri, 6 Oct 2006 15:57:24 GMT (405kb)

Title: KLM quantum computation with bosonic atoms

Authors: Sandu Popescu

Comments: 3 pages, 1 figure

\\

A Knill-Laflamme-Milburn (KLM) type quantum computation with bosonic neutral

atoms or bosonic ions is suggested. Crucially, as opposite to other quantum

computation schemes involving atoms (ions), no controlled interactions between

atoms (ions) involving their internal levels are required. Versus photonic KLM

computation this scheme has the advantage that single atom (ion) sources are

more natural than single photon sources, and single atom (ion) detectors are

far more efficient than single photon ones.

\\ ( http://arXiv.org/abs/quant-ph/0610043 , 405kb)

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Paper: cond-mat/0610198

Date: Sat, 7 Oct 2006 09:44:57 GMT (14kb)

Title: Effective Hamiltonian for repulsively bound pairs of particles in a

periodic potential

Authors: David Petrosyan, Michael Fleischhauer, James R. Anglin

Subj-class: Other

\\

Recently, Winkler et al. [Nature 441, 853 (2006)] have predicted and observed

repulsively bound atom pairs in an optical lattice whose dynamics is well

described by the Bose-Hubbard model valid in the tight-binding regime. When the

on-site repulsion between the particles exceeds the single-particle tunneling

rate between the neighboring sites of the periodic potential, such dimer states

are well localized at single sites and are stable on the time scale on which

the energy dissipation in the system can be neglected. Here we derive an

effective Hamiltonian for a lattice containing only even number of particles

per site. We then find that the interaction between dimers is a

nearest-neighbor attraction, which allows for the formation of attractively

bound clusters of repulsively bound pairs of particles.

\\ ( http://arXiv.org/abs/cond-mat/0610198 , 14kb)

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Paper: cond-mat/0610199

Date: Sat, 7 Oct 2006 11:52:59 GMT (203kb)

Title: Vector solitons in nearly-one-dimensional Bose-Einstein condensates

Authors: Luca Salasnich (CNISM and CNR-INFM, Padova) and Boris A. Malomed (Tel

Aviv Univ.)

Comments: 7 pages, 6 figures; Physical Review A, in press

Subj-class: Other

\\

We derive a system of nonpolynomial Schroedinger equations (NPSEs) for

one-dimensional wave functions of two components in a binary self-attractive

Bose-Einstein condensate loaded in a cigar-shaped trap. The system is obtained

by means of the variational approximation, starting from the coupled 3D

Gross-Pitaevskii equations and assuming, as usual, the factorization of 3D wave

functions. The system can be obtained in a tractable form under a natural

condition of symmetry between the two species. A family of vector

(two-component) soliton solutions is constructed. Collisions between orthogonal

solitons (ones belonging to the different components) are investigated by means

of simulations. The collisions are essentially inelastic. They result in strong

excitation of intrinsic vibrations in the solitons, and create a small

orthogonal component ("shadow") in each colliding soliton. The collision may

initiate collapse, which depends on the mass and velocities of the solitons.

\\ ( http://arXiv.org/abs/cond-mat/0610199 , 203kb)

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Paper: cond-mat/0610200

Date: Sun, 8 Oct 2006 03:21:13 GMT (516kb)

Title: Josephson Oscillation and Transition to Self-Trapping for

Bose-Einstein-Condensates in a Triple-Well Trap

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

Comments: 10 pages, 11 figures

Subj-class: Other

\\

We investigate the tunnelling dynamics of Bose-Einstein-Condensates(BECs) in

a symmetric as well as in a tilted triple-well trap within the framework of

mean-field treatment. The eigenenergies as the functions of the zero-point

energy difference between the tilted wells show a striking entangled star

structure when the atomic interaction is large. We then achieve insight into

the oscillation solutions around the corresponding eigenstates and observe

several new types of Josephson oscillations. With increasing the atomic

interaction, the Josephson-type oscillation is blocked and the self-trapping

solution emerges. The condensates are self-trapped either in one well or in two

wells but no scaling-law is observed near transition points. In particular, we

find that the transition from the Josephson-type oscillation to the

self-trapping is accompanied with some irregular regime where tunnelling

dynamics is dominated by chaos. The above analysis is facilitated with the help

of the Poicar\'{e} section method that visualizes the motions of BECs in a

reduced phase plane.

\\ ( http://arXiv.org/abs/cond-mat/0610200 , 516kb)

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Paper: cond-mat/0610210

Date: Sun, 8 Oct 2006 21:55:51 GMT (122kb)

Title: Time evolution algorithms for Matrix Product States and DMRG

Authors: Juan Jose Garcia-Ripoll

Comments: This work, with 18 pages and 17 figures, is a continuation/extension

of cond-mat/0602305

Subj-class: Strongly Correlated Electrons

\\

In this work we develop several new simulation algorithms for 1D many-body

quantum mechanical systems combining the Matrix Product State variational

ansatz with Taylor, Pad\'e and Arnoldi approximations to the evolution

operator. By comparing with previous techniques based on MPS and DMRG we

demonstrate that the Arnoldi method is the best one, reaching extremely good

accuracy with moderate resources. Finally we apply this algorithm to studying

how correlations are transferred from the atomic to the molecular cloud when

crossing a Feschbach resonance with two-species hard-core bosons in a 1D

optical lattice.

\\ ( http://arXiv.org/abs/cond-mat/0610210 , 122kb)

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Paper: cond-mat/0610221

Date: Mon, 9 Oct 2006 09:19:44 GMT (12kb)

Title: Bose-Einstein condensation of confined and non-interacting Bose

particles

Authors: Sang-Hoon Kim

Comments: 6 pages, 5 figures

Subj-class: Statistical Mechanics

\\

Using the grand-canonical statistics of non-interacting bosons in a three

dimensional harmonic trap, the Bose-Einstein condensation was studied.

Mathematical representation was based on Bose integral functions.

The relation between the particle number and its phase transition temperature

was clarified. The chemical potential was plotted. The mean energy and specific

heat which shown a $\lambda$-like sharp transition into the condensation was

studied.

\\ ( http://arXiv.org/abs/cond-mat/0610221 , 12kb)

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Paper: cond-mat/0610225

Date: Mon, 9 Oct 2006 12:55:27 GMT (171kb)

Title: Sequential superradiant scattering from atomic Bose-Einstein condensates

Authors: O. Zobay and G. M. Nikolopoulos

Comments: 9 pages, 4 figures. Submitted to Proceedings of LPHYS'06 workshop

Subj-class: Other

\\

We theoretically discuss several aspects of sequential superradiant

scattering from atomic Bose-Einstein condensates. Our treatment is based on the

semiclassical description of the process in terms of the Maxwell-Schroedinger

equations for the coupled matter-wave and optical fields. First, we investigate

sequential scattering in the weak-pulse regime and work out the essential

mechanisms responsible for bringing about the characteristic fan-shaped

side-mode distribution patterns. Second, we discuss the transition between the

Kapitza-Dirac and Bragg regimes of sequential scattering in the strong-pulse

regime. Finally, we consider the situation where superradiance is initiated by

coherently populating an atomic side mode through Bragg diffraction, as in

studies of matter-wave amplification, and describe the effect on the sequential

scattering process.

\\ ( http://arXiv.org/abs/cond-mat/0610225 , 171kb)

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Paper: cond-mat/0610238

Date: Mon, 9 Oct 2006 18:20:08 GMT (301kb)

Title: Condensation of N interacting bosons: Hybrid approach to condensate

fluctuations

Authors: Anatoly A. Svidzinsky and Marlan O. Scully

Comments: 6 pages, 4 figures, to appear in Phys. Rev. Lett

Subj-class: Statistical Mechanics

\\

We present a new method of calculating the distribution function and

fluctuations for a Bose-Einstein condensate (BEC) of N interacting atoms. The

present formulation combines our previous master equation and canonical

ensemble quasiparticle techniques. It is applicable both for ideal and

interacting Bogoliubov BEC and yields remarkable accuracy at all temperatures.

For the interacting gas of 200 bosons in a box we plot the temperature

dependence of the first four central moments of the condensate particle number

and compare the results with the ideal gas. For the interacting mesoscopic BEC,

as with the ideal gas, we find a smooth transition for the condensate particle

number as we pass through the critical temperature.

\\ ( http://arXiv.org/abs/cond-mat/0610238 , 301kb)

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Paper: cond-mat/0610242

Date: Mon, 9 Oct 2006 19:40:09 GMT (971kb)

Title: Formation of Vortices, Vortex Necklaces and Vortex Rings in Sliced

Condensates

Authors: N. Whitaker, P. G. Kevrekidis, R. Carretero-Gonzalez, D.J.

Frantzeskakis

Comments: 4 pages, 5 figures

Subj-class: Soft Condensed Matter

\\

In this Letter, we study the formation of vortices and vortex ring structures

as a result of the interference of higher-dimensional Bose-Einstein condensates

(BECs). This study is motivated by earlier experimental and theoretical studies

in quasi-one-dimensional condensates that produced interference fringes and the

one-dimensional analog of the structures obtained herein, namely dark solitary

waves. We highlight a number of additional possibilities that emerge in the

higher dimensional settings and elucidate their corresponding phenomenology.

For example, a condensate, initially split into eight fragments, gives rise to

a ``cage'' of vortex rings that surrounds the bulk of the condensed atoms. Our

results should be immediately tractable to currently existing experimental BEC

setups.

\\ ( http://arXiv.org/abs/cond-mat/0610242 , 971kb)

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Paper: quant-ph/0610051

Date: Sun, 8 Oct 2006 17:59:47 GMT (114kb)

Title: A new link between Boson and Fermion algebras: an alternative to

supersymmetry

Authors: Philip Davies

\\

In this paper we describe a new family of algebras which in the case of n = 2

reduces to the Fermion algebra and in the limiting case of n tends to infinity

reduces to the Boson algebra. These generalized algebras describe particles

which obey a generalized exclusion principle, limiting state occupation to

(n-1) and obeying a generalized particle statistics.

\\ ( http://arXiv.org/abs/quant-ph/0610051 , 114kb)

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Paper: quant-ph/0610053

Date: Mon, 9 Oct 2006 05:42:15 GMT (225kb)

Title: Features of Magneto-Optical Resonances in an Elliptically Polarized

Traveling Light Wave

Authors: D.V. Brazhnikov, A.V. Taichenachev, A.M. Tumaikin, V.I. Yudin, S.A.

Zibrov, Ya.O. Dudin, V.V. Vasil'ev, V.L. Velichansky

Comments: 5 pages

Journal-ref: D.V. Brazhnikov, A.V. Taichenachev, A.M. Tumaikin, V.I. Yudin,

S.A. Zibrov, Ya.O. Dudin, V.V. Vasil'ev, V.L. Velichansky, JETP Lett. 83(2),

64-68 (2006)

DOI: 10.1134/S0021364006020044

\\

The parameters of nonlinear absorption magneto-optical resonances in the

Hanle configuration have been studied as functions of the ellipticity of a

traveling light wave. It has been found that these parameters (amplitude,

width, and amplitude-to-width ratio) depend strongly on the polarization of the

light wave. In particular, the resonance amplitude can increase by more than an

order of magnitude when the polarization changes from linear to optimal

elliptic. It has been shown that this effect is associated with the Doppler

frequency shift for atoms in a gas. The theoretical results have been

corroborated in experiments in Rb vapor.

\\ ( http://arXiv.org/abs/quant-ph/0610053 , 225kb)

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Paper: quant-ph/0610054

Date: Mon, 9 Oct 2006 06:28:04 GMT (106kb)

Title: Effect of Atomic Coherence on Absorption in Four-level Systems: an

Analytical study

Authors: S N Sandhya

Comments: 15 pages 12 figures

\\

Absorption profile of a four-level ladder atomic system interacting with

three driving fields is studied perturbatively and analytical results are

presented. Numerical results where the driving field strengths are treated upto

all orders are presented. The absorption features is studied in two regimes, i)

the weak middle transition coupling, i.e.

$\Omega_2 << \Omega_{1,3}$ and ii) the strong middle transition coupling

$\Omega_2 >>\Omega_{1,3}$. In case i), it is shown that the ground state

absorption and the saturation characteristics of the population of level 2

reveal deviation due to the presence of upper level couplings. In particular,

the saturation curve for the population of level 2 shows a dip for $\Omega_1 =

\Omega_3$. While the populations of levels 3 and 4 show a maxima when this

resonance condition is satisfied. Thus the resonance condition provides a

criterion for maximally populating the upper levels. A second order

perturbation calculation reveals the nature of this minima (maxima). In the

second case, I report two important features: a) Filtering of the Aulter-Townes

doublet in the three-peak absorption profile of the ground state, which is

achieved by detuning only the upper most coupling field, and b) control of

line-width by controlling the strength of the upper coupling fields. This

filtering technique coupled with the control of linewidth could prove to be

very useful for high resolution studies.

\\ ( http://arXiv.org/abs/quant-ph/0610054 , 106kb)

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Paper: quant-ph/0610056

Date: Mon, 9 Oct 2006 10:47:06 GMT (136kb)

Title: Adiabatic Elimination in a Lambda System

Authors: E. Brion, L.H. Pedersen and K. Molmer

Comments: 14 pages, 3 figures

\\

This paper deals with different ways to extract the effective two-dimensional

lower level dynamics of a lambda system excited by off-resonant laser beams. We

present a commonly used procedure for elimination of the upper level, and we

show that it may lead to ambiguous results. To overcome this problem and better

understand the applicability conditions of this scheme, we review two rigorous

methods which allow us both to derive an unambiguous effective two-level

Hamiltonian of the system and to quantify the accuracy of the approximation

achieved: the first one relies on the exact solution of the Schrodinger

equation, while the second one resorts to the Green's function formalism and

the Feshbach projection operator technique.

\\ ( http://arXiv.org/abs/quant-ph/0610056 , 136kb)

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Paper: cond-mat/0610256

Date: Tue, 10 Oct 2006 08:49:37 GMT (13kb)

Title: Density functional theory of the trapped Fermi gas in the unitary regime

Authors: Brandon P. van Zyl, D. A. W. Hutchinson and Melodie Need

Subj-class: Other; Statistical Mechanics

\\

We investigate a density-functional theory (DFT) approach for an unpolarized

trapped dilute Fermi gas in the unitary limit . A reformulation of the recent

work of T. Papenbrock [Phys. Rev. A, {\bf 72}, 041602(R) (2005)] in the

language of fractional exclusion statistics allows us to obtain an estimate of

the universal factor, $\xi_{3D}$, in three dimensions (3D), in addition to

providing a systematic treatment of finite-$N$ corrections. We show that in 3D,

finite-$N$ corrections lead to unphysical values for $\xi_{3D}$, thereby

suggesting that a simple DFT applied to a small number of particles may not be

suitable in 3D. We then perform an analogous calculation for the

two-dimensional (2D) system in the infinite-scattering length regime, and

obtain a value of $\xi_{2D}=1$. Owing to the unique properties of the

Thomas-Fermi energy density-functional in 2D our result, in contrast to 3D, is

{\em exact} and therefore requires no finite-$N$ corrections.

\\ ( http://arXiv.org/abs/cond-mat/0610256 , 13kb)

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Paper: cond-mat/0610262

Date: Tue, 10 Oct 2006 10:18:09 GMT (62kb)

Title: Quasiperiodically driven ratchets for cold atoms

Authors: R. Gommers, S. Denisov and F. Renzoni

Comments: misprint in the label of Fig. 4 corrected

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

Journal-ref: Phys. Rev. Lett. 96, 240604 (2006)

\\

We investigate experimentally the route to quasiperiodicity in a driven

ratchet for cold atoms, and examine the relationship between symmetries and

transport while approaching the quasiperiodic limit. Depending on the specific

form of driving, quasiperiodicity results in the complete suppression of

transport, or into the restoration of the symmetries which hold for a periodic

driving.

\\ ( http://arXiv.org/abs/cond-mat/0610262 , 62kb)

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Paper: cond-mat/0610274

Date: Tue, 10 Oct 2006 16:51:01 GMT (59kb)

Title: Single-plane-wave Larkin-Ovchinnikov-Fulde-Ferrell state in

BCS--Bose-Einstein condensation crossover

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

Comments: 4 pages, 3 figures

Subj-class: Strongly Correlated Electrons; Superconductivity

\\

We study the single-plane-wave Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) states

for BCS--Bose-Einstein condensation (BEC) crossover at general temperatures

$T$. Because we include the important effects of noncondensed pairs, our $T

\neq 0$ phase diagrams are different from those reported in earlier work. We

find that generalized LOFF phases may be the ground state for a wide range of

(weak through moderately strong) interactions, including the unitary regime.

However, these LOFF phases are readily destroyed by non-zero $T$.

\\ ( http://arXiv.org/abs/cond-mat/0610274 , 59kb)

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Paper: quant-ph/0610029

Date: Thu, 5 Oct 2006 01:49:38 GMT (880kb)

Title: Cavity QED determination of atomic number statistics in optical lattices

Authors: W. Chen, D. Meiser, and P. Meystre

Comments: 10 pages revtex, 13 figures

Subj-class: Quantum Physics; Other; Atomic Physics

\\

We study the reflection of two counter-propagating modes of the light field

in a ring resonator by ultracold atoms either in the Mott insulator state or in

the superfluid state of an optical lattice. We obtain exact numerical results

for a simple two-well model and carry out statistical calculations appropriate

for the full lattice case. We find that the dynamics of the reflected light

strongly depends on both the lattice spacing and the state of the matter-wave

field. Depending on the lattice spacing, the light field is sensitive to

various density-density correlation functions of the atoms. The light field and

the atoms become strongly entangled if the latter are in a superfluid state, in

which case the photon statistics typically exhibit complicated multimodal

structures.

\\ ( http://arXiv.org/abs/quant-ph/0610029 , 880kb)

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Paper: quant-ph/0610064

Date: Tue, 10 Oct 2006 04:16:33 GMT (659kb)

Title: Measuring the quantum statistics of an atom laser beam

Authors: A. S. Bradley, M. K. Olsen, S. A. Haine and J. J. Hope

Comments: 4 pages, 3 figures

\\

We propose and analyse a scheme for measuring the quadrature statistics of an

atom laser beam using extant optical homodyning and Raman atom laser

techniques. Reversal of the normal Raman atom laser outcoupling scheme is used

to map the quantum statistics of an incoupled beam to an optical probe beam. A

multimode model of the spatial propagation dynamics shows that the Raman

incoupler gives a clear signal of de Broglie wave quadrature squeezing for both

pulsed and continuous inputs. Finally, we show that experimental realisations

of the scheme may be tested with existing methods via measurements of Glauber's

intensity correlation function.

\\ ( http://arXiv.org/abs/quant-ph/0610064 , 659kb)

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Paper: quant-ph/0610067

Date: Tue, 10 Oct 2006 10:27:15 GMT (106kb)

Title: Optical excitation spectrum of an atom in a surface-induced potential

Authors: Fam Le Kien, S. Dutta Gupta, and K. Hakuta

\\

We study the optical excitation spectrum of an atom in the vicinity of a

dielectric surface. We calculate the rates of the total scattering and the

scattering into the evanescent modes. With a proper assessment of the

limitations, we demonstrate the portability of the flat-surface results to an

experimental situation with a nanofiber. The effect of the surface-induced

potential on the excitation spectrum for free-to-bound transitions is shown to

be weak. On the contrary, the effect for bound-to-bound transitions is

significant leading to a large excitation linewidth, a substantial negative

shift of the peak position, and a strong long tail on the negative side and a

small short tail on the positive side of the field--atom frequency detuning.

\\ ( http://arXiv.org/abs/quant-ph/0610067 , 106kb)

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Paper: quant-ph/0610068

Date: Tue, 10 Oct 2006 10:45:55 GMT (329kb)

Title: Spontaneous radiative decay of translational levels of an atom near a

dielectric surface

Authors: Fam Le Kien and K. Hakuta

\\

We study spontaneous radiative decay of translational levels of an atom in

the vicinity of a semi-infinite dielectric. We systematically derive the

microscopic dynamical equations for the spontaneous decay process. We calculate

analytically and numerically the radiative linewidths and the spontaneous

transition rates for the translational levels. The roles of the interference

between the emitted and reflected fields and of the transmission into the

evanescent modes are clearly identified. Our numerical calculations for the

silica--cesium interaction show that the radiative linewidths of the bound

excited levels with large enough but not too large vibrational quantum numbers

are moderately enhanced by the emission into the evanescent modes and those for

the deep bound levels are substantially reduced by the surface-induced red

shift of the transition frequency.

\\ ( http://arXiv.org/abs/quant-ph/0610068 , 329kb)

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Paper: quant-ph/0610071

Date: Tue, 10 Oct 2006 13:37:15 GMT (296kb)

Title: Diffraction limited optics for single atom manipulation

Authors: Y.R.P. Sortais, H. Marion, C. Tuchendler, A.M. Lance, M. Lamare, P.

Fournet, C. Armellin, R. Mercier, G. Messin, A. Browaeys and P. Grangier

Comments: 8 pages, 9 figures

\\

We present an optical system designed to capture and observe a single neutral

atom in an optical dipole trap, created by focussing a laser beam using a large

numerical aperture N.A.=0.5 aspheric lens. We experimentally evaluate the

performance of the optical system and show that it is diffraction limited over

a broad spectral range (~ 200 nm) with a large transverse field (+/- 25

microns). The optical tweezer created at the focal point of the lens is able to

trap single atoms of 87Rb and to detect them individually with a large

collection efficiency. We measure the oscillation frequency of the atom in the

dipole trap, and use this value as an independent determination of the waist of

the optical tweezer. Finally, we produce with the same lens two dipole traps

separated by 2.2 microns and show that the imaging system can resolve the two

atoms.

\\ ( http://arXiv.org/abs/quant-ph/0610071 , 296kb)

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Paper: quant-ph/0610073

Date: Tue, 10 Oct 2006 15:32:15 GMT (68kb)

Title: Cavity enhanced light scattering in optical lattices to probe atomic

quantum statistics

Authors: Igor B. Mekhov, Christoph Maschler, Helmut Ritsch

Comments: 4 pages, 3 figures

\\

Different quantum states of atoms in optical lattices can be nondestructively

monitored through off-resonant light scattering into a cavity mode. Angle

resolved measurements of photon number and variance provide information about

atom-number fluctuations and pair correlations even without access to a single

site. Scattering into a standing-wave mode shows structure at angles where

classical diffraction gives zero. In particular for transverse illumination no

photons are scattered into a cavity for a Mott insulator, while the photon

number is proportional to the atom number for a superfluid.

\\ ( http://arXiv.org/abs/quant-ph/0610073 , 68kb)

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Paper: cond-mat/0610308

Date: Wed, 11 Oct 2006 17:02:06 GMT (33kb)

Title: Exact results for a charged, harmonically trapped quantum gas at

arbitrary temperature and magnetic field strength

Authors: Patrick Shea and Brandon P. van Zyl

Comments: To appear in Phys. Rev. B

Subj-class: Statistical Mechanics

\\

An analytical expression for the first-order density matrix of a charged,

two-dimensional, harmonically confined quantum gas, in the presence of a

constant magnetic field is derived. In contrast to previous results available

in the literature, our expressions are exact for any temperature and magnetic

field strength. We also present a novel factorization of the Bloch density

matrix in the form of a simple product with a clean separation of the

zero-field and field-dependent parts. This factorization provides an

alternative way of analytically investigating the effects of the magnetic field

on the system, and also permits the extension of our analysis to other

dimensions, and/or anisotropic confinement.

\\ ( http://arXiv.org/abs/cond-mat/0610308 , 33kb)

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Paper: cond-mat/0610314

Date: Wed, 11 Oct 2006 19:43:46 GMT (19kb)

Title: Energy-dependent effective interactions for dilute many-body systems

Authors: A. Collin, P. Massignan, and C. J. Pethick

Comments: 6 pages, 2 figures

Report-no: NORDITA-2006-34

Subj-class: Other

\\

We address the issue of determining an effective two-body interaction for

mean-field calculations of energies of many-body systems. We show that the

effective interaction is proportional to the phase shift, and demonstrate this

result in the quasiclassical approximation when there is a trapping potential

in addition to the short-range interaction between a pair of particles. We

calculate numerically energy levels for the case of an interaction with a

short-range square-well and a harmonic trapping potential and show that the

numerical results agree well with the analytical expression. We derive a

generalized Gross--Pitaevskii equation which includes effective range

corrections and discuss the form of the electron--atom effective interaction to

be used in calculations of Rydberg atoms and molecules.

\\ ( http://arXiv.org/abs/cond-mat/0610314 , 19kb)

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Paper: quant-ph/0610087

Date: Wed, 11 Oct 2006 09:45:06 GMT (532kb)

Title: Controlled Single-Photon Emission from a Single Trapped Two-Level Atom

Authors: Benoit Darqui\'{e} (LCFIO), Matthew Jones (LCFIO), Jos Dingjan

(LCFIO), Jerome Beugnon (LCFIO), Silvia Bergamini (LCFIO), Yvan Sortais

(LCFIO), Gaetan Messin (LCFIO), Antoine Browaeys (LCFIO), Philippe Grangier

(LCFIO)

Proxy: ccsd ccsd-00094645

Journal-ref: Science 309 (2005) 454

\\

By illuminating an individual rubidium atom stored in a tight optical tweezer

with short resonant light pulses, we create an efficient triggered source of

single photons with a well-defined polarization. The measured intensity

correlation of the emitted light pulses exhibits almost perfect antibunching.

Such a source of high rate, fully controlled single photon pulses has many

potential applications for quantum information processing.

\\ ( http://arXiv.org/abs/quant-ph/0610087 , 532kb)

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Paper (*cross-listing*): gr-qc/0610047

Date: Tue, 10 Oct 2006 18:03:28 GMT (58kb)

Title: Testing General Relativity with Atom Interferometry

Authors: Savas Dimopoulos, Peter W. Graham, Jason M. Hogan, Mark A. Kasevich

Comments: 4 pages, 1 figure

Subj-class: General Relativity and Quantum Cosmology; Atomic Physics

\\

The unprecedented precision of atom interferometry will soon lead to

laboratory tests of general relativity to levels that will rival or exceed

those reached by astrophysical observations. We propose such an experiment that

will initially test the equivalence principle to 1 part in 10^15 (300 times

better than the current limit), and 1 part in 10^17 in the future. It will also

probe general relativistic effects--such as the non-linear three-graviton

coupling, the gravity of an atom's kinetic energy, and the falling of light--to

several decimals. Further, in contrast to astrophysical observations,

laboratory tests can isolate these effects via their different functional

dependence on experimental variables.

\\ ( http://arXiv.org/abs/gr-qc/0610047 , 58kb)

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Paper: cond-mat/0610317

Date: Wed, 11 Oct 2006 20:25:40 GMT (61kb)

Title: Miscibility in a degenerate fermionic mixture induced by linear coupling

Authors: Sadhan K. Adhikari and Boris A. Malomed

Comments: 9 pages, 12 figures, PRA (in press)

Subj-class: Soft Condensed Matter

\\

We consider a one-dimensional mean-field-hydrodynamic model of a

two-component degenerate Fermi gas in an external trap, each component

representing a spin state of the same atom. We demonstrate that the

interconversion between them (linear coupling), imposed by a resonant

electromagnetic wave, transforms the immiscible binary gas into a miscible

state, if the coupling constant, $\kappa $, exceeds a critical value, $ \kappa

_{\mathrm{cr}}$. The effect is predicted in a variational approximation, and

confirmed by numerical solutions. Unlike the recently studied model of a binary

BEC with the linear coupling, the components in the immiscible phase of the

binary fermion mixture never fill two separated domains with a wall between

them, but rather form anti-locked ($\pi $ -phase-shifted) density waves.

Another difference from the bosonic mixture is spontaneous breaking of symmetry

between the two components in terms of numbers of atoms in them, $N_{1}$ and

$N_{2}$. The latter effect is characterized by the parameter $\nu \equiv

(N_{1}-N_{2})/(N_{1}+N_{2}) $ (only $N_{1}+N_{2}$ is a conserved quantity), the

onset of miscibility at $\kappa \geq \kappa_{\mathrm{cr}}$ meaning a transition

to $\nu \equiv 0$. At $\kappa <\kappa_{\mathrm{cr}}$, $\nu $ features damped

oscillations as a function of $\kappa $. We also briefly consider an asymmetric

model, with a chemical-potential difference between the two components.

\\ ( http://arXiv.org/abs/cond-mat/0610317 , 61kb)

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Paper: cond-mat/0610345

Date: Thu, 12 Oct 2006 15:38:01 GMT (38kb)

Title: Collective mode description for a clean Fermi gas with a repulsion in

arbitrary dimensions: interaction of spin excitations and its consequences

Authors: K.B. Efetov, I.L. Aleiner

Comments: A talk given at the conference "Mott's Physics in Nanowires and

Quantum Dots", Cambridge, UK, 2006

Subj-class: Strongly Correlated Electrons; Disordered Systems and Neural

Networks

\\

We discuss a recent bosonization method developed to study clean Fermi gases

with a repulsion in any dimensions. The method enables one to consider both

density and spin excitations. It is demonstrated that due to a non-abelian

structure of the effective theory, the spin excitations interact with each

other, which leads to new logarithmic in temperature corrections to physical

quantities. Using a renormalization group scheme constructed for the effective

low energy field theory these logarithms are summed up in all orders.

Temperature dependent corrections to the specific heat and spin susceptibility

are obtained for all dimensions d=1,2,3.

\\ ( http://arXiv.org/abs/cond-mat/0610345 , 38kb)

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Paper: quant-ph/0610095

Date: Thu, 12 Oct 2006 09:41:52 GMT (2kb)

Title: Comment on `Spin Decoherence in Superconducting Atom Chips'

Authors: Stefan Scheel, E. A. Hinds, and P. L. Knight

Comments: 1 page comment

\\

We comment on a recent paper [Phys. Rev. Lett. 97, 070401 (2006)] concerning

rubidium atoms trapped near a superconducting niobium surface at ~4K. This

seeks to calculate the rate of atomic spin flips induced by thermal magnetic

noise. We point out that the calculation is in error by a large factor because

it is based on the two-fluid model of superconductivity. This model gives a

poor description of electromagnetic dissipation just below the critical

temperature because it cannot incorporate the case II coherences of a fuller

quantum theory.

\\ ( http://arXiv.org/abs/quant-ph/0610095 , 2kb)

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Paper: quant-ph/0610099

Date: Thu, 12 Oct 2006 13:58:24 GMT (248kb)

Title: A class of quantum many-body states that can be efficiently simulated

Authors: G. Vidal

Comments: 4 pages, 5 figures

\\

We introduce the multi-scale entanglement renormalization ansatz (MERA), an

efficient representation of certain quantum many-body states on a D-dimensional

lattice. Equivalent to a quantum circuit with logarithmic depth and distinctive

causal structure, the MERA allows for an exact evaluation of local expectation

values. It is also the structure underlying entanglement renormalization, a

coarse-graining scheme for quantum systems on a lattice that is focused on

preserving entanglement.

\\ ( http://arXiv.org/abs/quant-ph/0610099 , 248kb)

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Replaced papers:

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Paper: cond-mat/0606151

replaced with revised version Fri, 6 Oct 2006 18:53:48 GMT (67kb)

Title: Structure of vortices in rotating Bose-Einstein condensates

Authors: Gentaro Watanabe, S. Andrew Gifford, Gordon Baym, C. J. Pethick

Comments: 10 pages, 9 figures

Report-no: NORDITA-2006-15

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

\\ ( http://arXiv.org/abs/cond-mat/0606151 , 67kb)

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Paper: cond-mat/0607138

replaced with revised version Fri, 6 Oct 2006 19:26:16 GMT (191kb)

Title: Color superfluidity and "baryon" formation in ultracold fermions

Authors: Akos Rapp, Gergely Zarand, Carsten Honerkamp, Walter Hofstetter

Comments: 5 PRL pages, 2 figures

Subj-class: Strongly Correlated Electrons; Superconductivity

\\ ( http://arXiv.org/abs/cond-mat/0607138 , 191kb)

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Paper: cond-mat/0607160

replaced with revised version Fri, 6 Oct 2006 13:21:22 GMT (60kb)

Title: Stability and excitations of solitons in 2D Bose-Einstein condensates

Authors: S. Tsuchiya, F. Dalfovo, C. Tozzo, and L. Pitaevskii

Comments: 6 pages, 2 figures, minor corrections, Proceedings of QFS 2006, to be

published in JLTP

Subj-class: Other

\\ ( http://arXiv.org/abs/cond-mat/0607160 , 60kb)

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Paper (*cross-listing*): math-ph/0605002

replaced with revised version Fri, 6 Oct 2006 16:40:48 GMT (47kb)

Title: Feynman cycles in the Bose gas

Authors: Daniel Ueltschi

Comments: 17 pages

Subj-class: Mathematical Physics; Statistical Mechanics

MSC-class: 82B10; 82B21; 82B26; 82D50

\\ ( http://arXiv.org/abs/math-ph/0605002 , 47kb)

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Paper: cond-mat/0510630

replaced with revised version Sat, 7 Oct 2006 10:20:57 GMT (25kb)

Title: Feshbach spectroscopy of a K-Rb atomic mixture

Authors: Francesca Ferlaino, Chiara D'Errico, Giacomo Roati, Matteo Zaccanti,

Massimo Inguscio, Giovanni Modugno, Andrea Simoni

Comments: 5 pages, revised version

Subj-class: Other

Journal-ref: Phys. Rev. A 73, 040702(R) (2006) and Erratum

\\ ( http://arXiv.org/abs/cond-mat/0510630 , 25kb)

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Paper: quant-ph/0608109

replaced with revised version Mon, 9 Oct 2006 15:53:13 GMT (68kb)

Title: Controlled splitting of an atomic wave packet

Authors: M. Zhang, P. Zhang, M. S. Chapman and L. you

Comments: 4 pages, 4 figures. Accepted by Phys. Rev. Lett

Journal-ref: Phys. Rev. Lett. 97, 070403 (2006)

\\ ( http://arXiv.org/abs/quant-ph/0608109 , 68kb)

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Paper: quant-ph/0610019

replaced with revised version Mon, 9 Oct 2006 12:08:45 GMT (325kb)

Title: Realization of a superconducting atom chip

Authors: Thomas Nirrengarten (LKB - Lhomond), Angie Qarry (LKB - Lhomond),

C\'{e}dric Roux (LKB - Lhomond), Andreas Emmert (LKB - Lhomond), Gilles

Nogues (LKB - Lhomond), Michel Brune (LKB - Lhomond), Jean-Michel Raimond

(LKB - Lhomond), Serge Haroche (LKB - Lhomond, CDF)

Comments: Submitted to Phys. Rev. Lett

Proxy: ccsd ccsd-00103290

\\ ( http://arXiv.org/abs/quant-ph/0610019 , 325kb)

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Paper (*cross-listing*): math-ph/0606058

replaced with revised version Tue, 10 Oct 2006 09:01:12 GMT (25kb)

Title: Rapidly Rotating Bose-Einstein Condensates in Strongly Anharmonic Traps

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

Comments: LaTex2e, 27 pages, slightly revised version, typos fixed

Subj-class: Mathematical Physics; Statistical Mechanics

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

\\ ( http://arXiv.org/abs/math-ph/0606058 , 25kb)

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Paper: cond-mat/0606743

replaced with revised version Wed, 11 Oct 2006 18:57:03 GMT (61kb)

Title: Prediction of quantum stripe ordering in optical lattices

Authors: Congjun Wu, W. Vincent Liu, Joel Moore, and Sankar Das Sarma

Comments: 4 pages, three figures, accepted by Phys. Rev. Lett

Subj-class: Strongly Correlated Electrons; Superconductivity

\\ ( http://arXiv.org/abs/cond-mat/0606743 , 61kb)

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Paper: cond-mat/0607459

replaced with revised version Wed, 11 Oct 2006 22:23:14 GMT (257kb)

Title: Superfluidity in Three-species Mixture of Fermi Gases across Feshbach

Resonances

Authors: Hui Zhai

Comments: 4 pages, 3 figures, revised version

Subj-class: Superconductivity

\\ ( http://arXiv.org/abs/cond-mat/0607459 , 257kb)

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Paper: cond-mat/0608255

replaced with revised version Wed, 11 Oct 2006 22:40:29 GMT (262kb)

Title: FFLO Vortex Lattice States in Cold Fermionic-Atom Systems

Authors: Y.-P. Shim, R. A. Duine, and A. H. MacDonald

Comments: 10 pages, 9 figures, accepted for publication in Phys. Rev. A

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0608255 , 262kb)

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Paper: cond-mat/0609748

replaced with revised version Thu, 12 Oct 2006 17:35:58 GMT (42kb)

Title: Quantum Noise Analysis of Spin Systems Realized with Cold Atoms

Authors: R. W. Cherng, Eugene Demler

Comments: 18 pages, 4 figures, updated acknowledgements

Subj-class: Strongly Correlated Electrons; Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0609748 , 42kb)

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Till next week,

Matt.

-- ========================================================================= Dr M. J. Davis, Senior Lecturer in Physics School of Physical Sciences, email: mdavis_at_physics.uq.edu.au University of Queensland, ph : +61 7 334 69824 Brisbane, QLD 4072, fax : +61 7 336 51242 Australia. http://www.physics.uq.edu.au/people/mdavis/ ========================================================================= Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland =========================================================================Received on Wed Oct 18 2006 - 17:50:19 EST

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