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

Date: Tue, 25 Jul 2006 02:18:55 +1000 (EST)

Date: Tue, 25 Jul 2006 02:18:55 +1000 (EST)

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

Hi all,

This week I would like to offer my apologies to Griessner et al., whom it seems

I left out of my last arXiv mailing. Therefore their paper comes first this

week. If anyone notices that I miss your relevant paper, kindly let me know and

it will take pride of place the following week.

I am officially on holiday next week, but the arXiv mailing should still go

ahead.

The abstracts:

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Paper: cond-mat/0607254

Date: Mon, 10 Jul 2006 20:10:42 GMT (129kb)

Title: Dark state cooling of atoms by superfluid immersion

Authors: A. Griessner, A. J. Daley, S. R. Clark, D. Jaksch, and P. Zoller

Comments: 4 pages, 4 figures, RevTeX 4

Subj-class: Other

\\

We propose and analyse a scheme to cool atoms in an optical lattice to

ultra-low temperatures within a Bloch band, and away from commensurate filling.

The protocol is inspired by ideas from dark state laser cooling, but replaces

electronic states with motional levels, and spontaneous emission of photons by

emission of phonons into a Bose-Einstein condensate, in which the lattice is

immersed. In our model, achievable temperatures correspond to a small fraction

of the Bloch band width, and are much lower than the reservoir temperature.

\\ ( http://arXiv.org/abs/cond-mat/0607254 , 129kb)

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Paper: cond-mat/0607320

Date: Thu, 13 Jul 2006 17:07:58 GMT (5kb)

Title: Hydrodynamics of Superfluid Bose Gases in an Optical Lattice at Finite

Temperatures

Authors: Satoru Konabe and Tetsuro Nikuni

Comments: 6pages, submitted to Quantum Fluids and Solids Conference (QFS 2006)

Subj-class: Other

\\

Starting from an effective action for the order parameter field, we derive a

coupled set of generalized hydrodynamic equations for a Bose condensate in an

optical lattice at finite temperatures. Using the linearized hydrodynamic

equations, we study the microscopic mechanism of the Landau instability due to

the collisional damping process between condensate and noncondensate atoms. It

is shown that the Landau criterion of the superfluidity for the uniform system

is modified due to the presence of the periodic optical lattice potential.

\\ ( http://arXiv.org/abs/cond-mat/0607320 , 5kb)

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Paper: cond-mat/0607328

Date: Thu, 13 Jul 2006 12:31:10 GMT (345kb)

Title: Bose-Einstein condensation of strongly correlated electrons and phonons

in cuprate superconductors

Authors: A.S. Alexandrov

Comments: 35 pages, 10 figures, invited paper for the special volume of Journal

of Physics: Condensed Matter

Subj-class: Superconductivity; Strongly Correlated Electrons

\\

The long-range Froehlich electron-phonon interaction has been identified as

the most essential for pairing in high-temperature superconductors owing to

poor screening, as is now confirmed by optical, isotope substitution, recent

photoemission and some other measurements. I argue that low energy physics in

cuprate superconductors is that of superlight small bipolarons, which are

real-space hole pairs dressed by phonons in doped charge-transfer Mott

insulators. They are itinerant quasiparticles existing in the Bloch states at

low temperatures as also confirmed by continuous-time quantum Monte-Carlo

algorithm (CTQMC) fully taking into account realistic Coulomb and long-range

Froehlich interactions. Here I suggest that a parameter-free evaluation of Tc,

unusual upper critical fields, the normal state Nernst effect, diamagnetism,

the Hall-Lorenz numbers and giant proximity effects strongly support the

three-dimensional (3D) Bose-Einstein condensation of mobile small bipolarons

with zero off-diagonal order parameter above the resistive critical temperature

$T_c$ at variance with phase fluctuation scenarios of cuprates.

\\ ( http://arXiv.org/abs/cond-mat/0607328 , 345kb)

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Paper: cond-mat/0607331

Date: Thu, 13 Jul 2006 13:38:56 GMT (15kb)

Title: Semiclassical corrections to the interaction energy of a hard-sphere

Boltzmann gas

Authors: R. K. Bhaduri, W. van Dijk, and M. K. Srivastava

Comments: 9 pages, 3 figures, submitted to Eur. J. Phys

Subj-class: Statistical Mechanics

\\

Quantum effects in statistical mechanics are important when the thermal

wavelength is of the order of, or greater than, the mean interatomic spacing.

This is examined at depth taking the example of a hard-sphere Boltzmann gas.

Using the virial expansion for the equation of state, it is shown that the

interaction energy of a classical hard-sphere gas is exactly zero. When the

(second) virial coefficient of such a gas is obtained quantum mechanically,

however, the quantum contribution to the interaction energy is shown to be

substantial. The importance of the semiclassical corrections to the interaction

energy shows up dramatically in such a system.

\\ ( http://arXiv.org/abs/cond-mat/0607331 , 15kb)

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Paper: cond-mat/0607332

Date: Thu, 13 Jul 2006 13:50:28 GMT (48kb)

Title: Quantum effects in the dynamical localization of Bose-Einstein

condensates in optical lattices

Authors: Beata J. Dabrowska-Wuester, Sebastian Wuester, Ashton S. Bradley,

Matthew J. Davis and Elena A. Ostrovskaya

Subj-class: Other

\\

We study quantum effects in the dynamics of a Bose-Einstein condensate loaded

onto the edge of a Brillouin zone of a one-dimensional periodic potential

created by an optical lattice. We show that quantum fluctuations trigger the

dynamical instability of the Bloch states of the condensate and can lead to the

generation of arrays of matter-wave gap solitons. Our approach also allows us

to study the instability-induced anomalous heating of the condensate at the

edge of the Brillouin zone and growth of the uncondensed atomic fraction. We

demonstrate that there are regimes in which the heating effects do not suppress

the formation of the localised states. We show that a phase imprinting

technique can ensure the formation of gap soliton trains after short evolution

times and at fixed positions.

\\ ( http://arXiv.org/abs/cond-mat/0607332 , 48kb)

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Paper: cond-mat/0607334

Date: Thu, 13 Jul 2006 15:33:41 GMT (63kb)

Title: Bragg Spectroscopy of Cold Atomic Fermi Gases

Authors: G. M. Bruun, Gordon Baym

Comments: 8 pages, 9 figures

Subj-class: Superconductivity

\\

We propose a Bragg spectroscopy experiment to measure the onset of superfluid

pairing in ultracold trapped Fermi gases. In particular, we study two component

Fermi gases in the weak coupling BCS and BEC limits as well as in the strong

coupling unitarity limit. The low temperature Bragg spectrum exhibits a gap

directly related to the pair-breaking energy. Furthermore, he Bragg spectrum

has a large maximum just below the critical temperature when the gas is

superfluid in the BCS limit. In the unitarity regime, we show how the pseudogap

in the normal phase leads to a significant suppression of the low frequency

Bragg spectrum.

\\ ( http://arXiv.org/abs/cond-mat/0607334 , 63kb)

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Paper: cond-mat/0607340

Date: Thu, 13 Jul 2006 19:15:08 GMT (584kb)

Title: Hyperspherical Description of the Degenerate Fermi Gas: S-wave

Interactions

Authors: Seth T. Rittenhouse (1), M. J. Cavagnero (2), Javier von Stecher (1),

Chris H. Greene (1) ((1)University of Colorado, (2) University of Kentucky)

Subj-class: Other

\\

We present a unique theoretical description of the physics of the spherically

trapped $N$-atom degenerate Fermi gas (DFG) at zero temperature based on an

ordinary Schr\"{o}dinger equation with a microscopic, two body interaction

potential. With a careful choice of coordinates and a variational wavefunction,

the many body Schr\"{o}dinger equation can be accurately described by a

\emph{linear}, one dimensional effective Schr\"{o}dinger equation in a single

collective coordinate, the rms radius of the gas. Comparisons of the energy,

rms radius and peak density of ground state energy are made to those predicted

by Hartree-Fock (HF). Also the lowest radial excitation frequency (the

breathing mode frequency) agrees with a sum rule calculation, but deviates from

a HF prediction.

\\ ( http://arXiv.org/abs/cond-mat/0607340 , 584kb)

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Paper: cond-mat/0512472

replaced with revised version Thu, 13 Jul 2006 08:51:36 GMT (72kb)

Title: Fermionic superfluidity with positive scattering length

Authors: Bout Marcelis and Servaas Kokkelmans

Comments: 6 pages, 3 figures; v2: added references and details energy-dependent

interaction

Subj-class: Statistical Mechanics; Superconductivity

\\ ( http://arXiv.org/abs/cond-mat/0512472 , 72kb)

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Paper: cond-mat/0605085

replaced with revised version Thu, 13 Jul 2006 10:16:23 GMT (37kb)

Title: Finite temperature thermodynamics of two-component ultracold Fermi gas

Authors: Armen Sedrakian, Herbert M\"uther, Artur Polls

Comments: 4 pages, 3 figures. v2 includes a discussion of instabilities

Subj-class: Superconductivity; Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0605085 , 37kb)

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Paper: quant-ph/0607079

Date: Thu, 13 Jul 2006 08:14:20 GMT (130kb)

Title: Exact propagators for atom-laser interactions

Authors: A. del Campo, J. G. Muga

Comments: 13 pages, 6 figures

\\

A class of exact propagators describing the interaction of an $N$-level atom

with a set of on-resonance $\delta$-lasers is obtained by means of the Laplace

transform method. State-selective mirrors are described in the limit of strong

lasers. The ladder, V and $\Lambda$ configurations for a three-level atom are

discussed. For the two level case, the transient effects arising as result of

the interaction between both a semi-infinite beam and a wavepacket with the

on-resonance laser are examined.

\\ ( http://arXiv.org/abs/quant-ph/0607079 , 130kb)

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Paper: cond-mat/0607358

Date: Fri, 14 Jul 2006 08:24:58 GMT (179kb)

Title: A Scanning Electron Microscope for Ultracold Atoms

Authors: T. Gericke, C. Utfeld, N. Hommerstad, H. Ott

Comments: 5 pages, 2 figures

Subj-class: Statistical Mechanics

Journal-ref: Laser Phys. Lett. 3, 415-419 (2006)

DOI: 10.1002/lapl.200610028

\\

We propose a new technique for the detection of single atoms in ultracold

quantum gases. The technique is based on scanning electron microscopy and

employs the electron impact ionization of trapped atoms with a focussed

electron probe. Subsequent detection of the resulting ions allows for the

reconstruction of the atoms position. This technique is expected to achieve a

much better spatial resolution compared to any optical detection method. In

combination with the sensitivity to single atoms, it makes new in situ

measurements of atomic correlations possible. The detection principle is also

well suited for the addressing of individual sites in optical lattices.

\\ ( http://arXiv.org/abs/cond-mat/0607358 , 179kb)

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Paper: cond-mat/0607359

Date: Fri, 14 Jul 2006 08:32:13 GMT (287kb)

Title: Landau-Zener Tunnelling in a Nonlinear Three-level System

Authors: Guan-Fang Wang, Di-Fa Ye, Li-Bin Fu, Xu-Zong Chen, and Jie Liu

Comments: 8 pages, 8 figures

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\

We present a comprehensive analysis of the Landau-Zener tunnelling of a

nonlinear three-level system in a linearly sweeping external field. We find the

presence of nonzero tunnelling probability in the adiabatic limit (i.e., very

slowly sweeping field) even for the situation that the nonlinear term is very

small and the energy levels keep the same topological structure as that of

linear case. In particular, the tunnelling is irregular with showing an

unresolved sensitivity on the sweeping rate. For the case of fast-sweeping

fields, we derive an analytic expression for the tunnelling probability with

stationary phase approximation and show that the nonlinearity can dramatically

influence the tunnelling probability when the nonlinear "internal field"

resonate with the external field. We also discuss the asymmetry of the

tunnelling probability induced by the nonlinearity. Physics behind the above

phenomena is revealed and possible application of our model to triple-well

trapped Bose-Einstein condensate is discussed.

\\ ( http://arXiv.org/abs/cond-mat/0607359 , 287kb)

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Paper: cond-mat/0607361

Date: Fri, 14 Jul 2006 09:00:23 GMT (73kb)

Title: Collective excitations of a Bose-Einstein condensate in an anharmonic

trap

Authors: Guan-Qiang Li, Li-Bin Fu, Ju-Kui Xue, Xu-Zong Chen, and Jie Liu

Comments: 5 pages, 4 figures

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\

We investigate the collective excitations of a one-dimensional Bose-Einstein

condensate (BEC) with repulsive interaction between atoms in a quadratic plus

quartic trap. By using the variational approach, the coupled equations of

motion for the center-of-mass coordinate of the condensate and its width are

derived. Then, two low-energy excitation modes are obtained analytically. The

frequency shift induced by the anharmonic distortion, and the collapse and

revival of the collective excitations, which originate from the nonlinear

coupling between the two modes, are discussed.

\\ ( http://arXiv.org/abs/cond-mat/0607361 , 73kb)

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Paper: cond-mat/0607371

Date: Fri, 14 Jul 2006 12:34:53 GMT (18kb)

Title: Quantum fluctuations and collective oscillations of a Bose-Einstein

condensate in a 2D optical lattice

Authors: G. Orso, C. Menotti and S. Stringari

Comments: 5 pages, 3 figures

Subj-class: Other

\\

We use Bogoliubov theory to calculate the beyond mean field correction to the

equation of state of a weakly interacting Bose gas in the presence of a tight

2D optical lattice. We show that the lattice induces a characteristic 3D to 1D

crossover in the behaviour of quantum fluctuations. Using the hydrodynamic

theory of superfluids, we calculate the corresponding shift of the collective

frequencies of a harmonically trapped gas. We find that this correction can be

of the order of a few percent and hence easily measurable in current

experiments. The behavior of the quantum depletion of the condensate is also

discussed.

\\ ( http://arXiv.org/abs/cond-mat/0607371 , 18kb)

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Paper: cond-mat/0605138

replaced with revised version Fri, 14 Jul 2006 10:00:17 GMT (52kb)

Title: Landau functions for non-interacting bosons

Authors: Andreas Sinner, Florian Schuetz, and Peter Kopietz

Comments: 4 pages, 4 figures; final version to appear as a rapid communication

in Physical Review A. Abstract modified and typos corrected

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0605138 , 52kb)

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Paper: quant-ph/0607094

Date: Fri, 14 Jul 2006 12:16:57 GMT (14kb)

Title: Quantum simulations under translational symmetry

Authors: Christina V. Kraus, Michael M. Wolf, J. Ignacio Cirac

Comments: 8 pages

\\

We investigate the power of quantum systems for the simulation of Hamiltonian

time evolutions on a cubic lattice under the constraint of translational

invariance. Given a set of translationally invariant local Hamiltonians and

short range interactions we determine time evolutions which can and those that

can not be simulated. Whereas for general spin systems no finite universal set

of generating interactions is shown to exist, universality turns out to be

generic for quadratic bosonic and fermionic nearest-neighbor interactions when

supplemented by all translationally invariant on-site Hamiltonians.

\\ ( http://arXiv.org/abs/quant-ph/0607094 , 14kb)

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Paper: quant-ph/0607098

Date: Fri, 14 Jul 2006 14:43:47 GMT (30kb)

Title: How to measure the wave-function absolute squared of a moving particle:

do it with mirrors

Authors: Volker Hannstein Gerhard C. Hegerfeldt

Comments: 4 pages, 4 figures

\\

We consider a slow particle with wave function $\psi_t(\vec{x})$, moving

freely in some direction. A mirror is briefly switched on around a time $T$ and

its position is scanned. It is shown that the measured reflection probability

then allows the determination of $|\psi_T(\vec{x})|^2$. Experimentally

available atomic mirrors should make this method applicable to the

center-of-mass wave function of atoms with velocities in the cm/s range.

\\ ( http://arXiv.org/abs/quant-ph/0607098 , 30kb)

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Paper: physics/0607140

Date: Fri, 14 Jul 2006 14:52:21 GMT (516kb)

Title: Effective-range description of a Bose gas under strong one- or

two-dimensional confinement

Authors: Pascal Naidon, Eite Tiesinga, William F. Mitchell, and Paul S.

Julienne

Comments: 6 pages, 3 figures

Subj-class: Atomic Physics

\\

We point out that theories describing s-wave collisions of bosonic atoms

confined in one- or two-dimensional geometries can be extended to much tighter

confinements than previously thought. This is achieved by replacing the

scattering length by an energy-dependent scattering length which was already

introduced for the calculation of energy levels under 3D confinement. This

replacement accurately predicts the position of confinement-induced resonances

in strongly confined geometries.

\\ ( http://arXiv.org/abs/physics/0607140 , 516kb)

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Paper: cond-mat/0607397

Date: Sat, 15 Jul 2006 20:33:59 GMT (142kb)

Title: Heisenberg limited interferometry via a two-component Mott insulating to

superfluid transition

Authors: M. Rodr\'iguez, S. R. Clark, and D. Jaksch

Comments: 4 pages, 4 figures

Subj-class: Mesoscopic Systems and Quantum Hall Effect

\\

We propose the dynamical creation of twin-Fock and macroscopic superposition

states, which both exhibit Heisenberg limited interferometric phase

sensitivities, in an optical lattice. In our scheme a two-component Mott

insulator with two bosonic atoms per lattice site is melted into a superfluid.

This process transforms local correlations between hyperfine states of atom

pairs into multi-particle correlations extending over the whole system. The

melting time does not scale with the system size which makes our scheme

experimentally feasible.

\\ ( http://arXiv.org/abs/cond-mat/0607397 , 142kb)

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Paper: cond-mat/0607401

Date: Sun, 16 Jul 2006 15:25:19 GMT (16kb)

Title: Probing the Superfluid - Mott Insulating Shell Structure of Cold Atoms

by Parametric Excitations

Authors: Lilach Goren, Eros Mariani and Ady Stern

Comments: 4 pages, 1 figure

Subj-class: Other

\\

We study the effect of parametric excitations on systems of confined

ultracold Bose atoms in periodically modulated optical lattices. In the regime

where Mott insulating and Superfluid domains coexist, we show that the

dependence of the energy absorbed by the system on the frequency of the

modulation serves as an experimental probe for the existence and properties of

Mott insulating-Superfluid domains.

\\ ( http://arXiv.org/abs/cond-mat/0607401 , 16kb)

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Paper: cond-mat/0607405

Date: Mon, 17 Jul 2006 08:16:26 GMT (434kb)

Title: Density fingerprint of giant vortices in Fermi gases near a Feshbach

resonance

Authors: Hui Hu and Xia-Ji Liu

Comments: 4 pages and 5 figures

Subj-class: Superconductivity; Strongly Correlated Electrons

\\

The structure of multiply quantized or giant vortex states in atomic Fermi

gases across a Feshbach resonance is studied within the context of

self-consistent Bogoliubov-de Gennes theory. The particle density profile of

vortices with $\kappa>1$ flux quanta is calculated. Owing to $\kappa$ discrete

branches of vortex core bound states, inside the core the density oscillates as

a function of the distance from the vortex line and displays a non-monotoic

dependence on the interaction strengths, in marked contrast to the singly

quantized case, in which the density depletes monotonically. This feature,

never reported so far, can make a direct visualization of the giant vortices in

atomic Fermi gases.

\\ ( http://arXiv.org/abs/cond-mat/0607405 , 434kb)

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Paper: cond-mat/0607412

Date: Mon, 17 Jul 2006 10:58:17 GMT (5kb)

Title: Bose-Einstein Condensation and Casimir Force of Trapped Bose Gas to Slabs

Authors: Shyamal Biswas

Comments: 3 pages

Subj-class: Statistical Mechanics

For Bose gas in 3-d box with slab geometry it has been shown that at and below

the condensation temperature thermodynamic Casimir force appears (Martin and

Zagrebnov $[Europhys. Lett.,{\bf73} (2006) 15]$). This Casimir force has a

classical expression which is independent of $\hbar$. At finite temperatures

this force for photons in between two plates also has the classical expression

independent of $\hbar$. We study the Bose-Einstein Condensation for a 3-d system

of Bose gas which is harmonically trapped along two perpendicular directions and

is confined in between two slabs along the other perpendicular direction. We

calculate the Casimir force between the two slabs for this system of trapped

Bose gas. At finite temperatures the Casimir force for our system depends on

$\hbar$

\\ ( http://arXiv.org/abs/cond-mat/0607412 , 5kb)

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Paper: physics/0607149

Date: Mon, 17 Jul 2006 06:06:33 GMT (416kb)

Title: Multiple optical traps from a single laser beam using a mechanical

element

Authors: J.A. Dharmadhikari, A.K. Dharmadhikari, and D. Mathur

Comments: 8 pages, 3 figures, submitted to Applied Physics Letters in January

2006

Subj-class: Optics; Biological Physics

\\

The use of a wire mesh facilitates creation of multiple optical traps for

manipulation of small micron or sub-micron particles. Such an array of optical

traps can be easily controlled. The trap that is formed in this manner is a

continuous trap; it obviates the need to time share a laser beam among a set of

positions, as is presently done in conventional multiple traps.

\\ ( http://arXiv.org/abs/physics/0607149 , 416kb)

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Paper: cond-mat/0607433

Date: Tue, 18 Jul 2006 02:03:45 GMT (45kb)

Title: Coherent Collective Excitations in a Superfluid: Broken Symmetries and

Fluctuations-Dissipation

Authors: S.J. Han

Comments: 44 pages and 1 figure

Subj-class: Other

\\

We discuss the phase coherent collective excitations in both He II and atomic

Bose condensate. It is shown that a spontaneously broken gauge symmetry, which

always accompanies a longitudinal phonon (Nambu-Goldstone boson), takes place

at a nodal surface in a finite inhomogeneous Bose system. It is further shown

that the broken gauge symmetry is both a necessary and a sufficient condition

for the conservation of energy in an isolated system. We also give a detailed

discussion on the behavior of a surface layer of He II in which the two-fluid

model breaks down.

\\ ( http://arXiv.org/abs/cond-mat/0607433 , 45kb)

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Paper: cond-mat/0607434

Date: Tue, 18 Jul 2006 02:36:31 GMT (245kb)

Title: Thermal dissipation in quantum turbulence

Authors: Michikazu Kobayashi and Makoto Tsubota

Comments: 4 pages, 6 figures, submitted to APS

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

\\

The microscopic mechanism of thermal dissipation in quantum turbulence has

been numerically studied by solving the coupled system involving the

Gross-Pitaevskii equation and the Bogoliubov-de Gennes equation. At low

temperatures, the obtained dissipation does not work at scales greater than the

vortex core size. However, as the temperature increases, dissipation works at

large scales and it affects the vortex dynamics. We successfully obtained the

mutual friction coefficients of the vortex dynamics as functions of

temperature, which can be applied to the vortex dynamics in dilute

Bose-Einstein condensates.

\\ ( http://arXiv.org/abs/cond-mat/0607434 , 245kb)

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Paper: cond-mat/0607438

Date: Tue, 18 Jul 2006 07:11:43 GMT (157kb)

Title: A Guided Quasicontinuous Atom Laser

Authors: William Guerin (LCFIO), Jean-F\'{e}lix Riou (LCFIO), John P. Gaebler

(LCFIO), Vincent Josse (LCFIO), Philippe Bouyer (LCFIO), Alain Aspect (LCFIO)

Proxy: ccsd ccsd-00085308

Subj-class: Other

\\

We report the first realization of a guided quasicontinuous atom laser by rf

outcoupling a BEC from a hybrid optomagnetic trap into a horizontal atomic

waveguide. This configuration allows us to cancel the acceleration due to

gravity and thus to keep the de Broglie wavelength constant at a value of about

0.5 $\mu$m during 0.1 s of propagation. We also show that our configuration,

equivalent to pigtailing an optical fiber to a (photon) semiconductor laser,

ensures an intrinsically good transverse mode matching.

\\ ( http://arXiv.org/abs/cond-mat/0607438 , 157kb)

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Paper: cond-mat/0607453

Date: Tue, 18 Jul 2006 17:52:16 GMT (47kb)

Title: Orthogonality catastrophe and shock waves in a non-equilibrium Fermi gas

Authors: E. Bettelheim, A. G. Abanov, and P. Wiegmann

Comments: 5 pages, 1 figure, revtex4, prl

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

Effect

\\

A semiclassical wave-packet propagating in a dissipationless Fermi gas

inevitably enters a "gradient catastrophe" regime, where an initially smooth

front develops large gradients and undergoes a dramatic shock wave phenomenon.

The non-linear effects in electronic transport are due to the curvature of the

electronic spectrum at the Fermi surface. They can be probed by a sudden

switching of a local potential. In equilibrium, this process produces a large

number of particle-hole pairs, a phenomenon closely related to the

Orthogonality Catastrophe. We study a generalization of this phenomenon to the

non-equilibrium regime and show how the Orthogonality Catastrophe cures the

Gradient Catastrophe, providing a dispersive regularization mechanism. We show

that a wave packet overturns and collapses into modulated oscillations with the

wave vector determined by the height of the initial wave. The oscillations

occupy a growing region extending forward with velocity proportional to the

initial height of the packet. We derive a fundamental equation for the

transition rates (MKP-equation) and solve it by means of the Whitham modulation

theory.

\\ ( http://arXiv.org/abs/cond-mat/0607453 , 47kb)

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Paper: cond-mat/0507586

replaced with revised version Tue, 18 Jul 2006 11:56:21 GMT (73kb)

Title: Phase diagram of a cold polarized Fermi gas

Authors: D.T.Son, M.A.Stephanov

Comments: 6 pages, 5 figures; added an Appendix on the global stability of the

splitting point

Report-no: INT-PUB 05-18

Subj-class: Other

Journal-ref: Phys.Rev. A74 (2006) 013614

DOI: 10.1103/PhysRevA.74.013614

\\ ( http://arXiv.org/abs/cond-mat/0507586 , 73kb)

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Paper: cond-mat/0607253

replaced with revised version Tue, 18 Jul 2006 15:26:21 GMT (45kb)

Title: Classifying Novel Phases of Spinor Atoms

Authors: Ryan Barnett, Ari Turner, Eugene Demler

Comments: Added references

Subj-class: Strongly Correlated Electrons

\\ ( http://arXiv.org/abs/cond-mat/0607253 , 45kb)

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Paper: quant-ph/0607121

Date: Tue, 18 Jul 2006 10:21:58 GMT (128kb)

Title: Scattering of two-level atoms by delta lasers: Exactly solvable models

in atom optics

Authors: D. Seidel, J.G. Muga, G.C. Hegerfeldt

Comments: 11 pages, 5 figures

\\

We study the scattering of two-level atoms at narrow laser fields, modeled by

a $\delta$-shape intensity profile. The unique properties of these potentials

allow us to give simple analytic solutions for one or two field zones. Several

applications are studied: a single $\delta$-laser may serve as a detector model

for atom detection and arrival-time measurements, either by means of

fluorescence or variations in occupation probabilities. We show that, in

principle, this ideal detector can measure the particle density, the quantum

mechanical flux, arrival time distributions or local kinetic energy densities.

Moreover, two spatially separated $\delta$-lasers are used to investigate

quantized-motion effects on Ramsey interferometry.

\\ ( http://arXiv.org/abs/quant-ph/0607121 , 128kb)

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Paper: quant-ph/0605245

replaced with revised version Tue, 18 Jul 2006 13:57:35 GMT (66kb)

Title: Manipulating Single Neutral Atoms in Optical Lattices

Authors: Chuanwei Zhang, S. L. Rolston, and S. Das Sarma

Comments: 5 pages, 3 figures, a typos for the focused laser intensity pattern

is corrected. No results change

Subj-class: Quantum Physics; Soft Condensed Matter

\\ ( http://arXiv.org/abs/quant-ph/0605245 , 66kb)

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Paper: cond-mat/0607459

Date: Tue, 18 Jul 2006 21:55:44 GMT (257kb)

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

Resonances

Authors: Hui Zhai

Comments: 4 pages, 3 figures

Subj-class: Superconductivity

\\

In this letter we study the phase diagram and the properties of the

superfluid phase in a mixture of the lowest three hyperfine spin states of

lithium, within a particular range of magnetic field where two Feshbach

resonances are close to each other. In the BEC side of two resonances the

system is a binary mixture of molecular condensates, which undergoes a

crossover to a superfluid containing two kinds of Cooper pairs as approaching

resonances. Some remarkable properties, as well as the experimental

consequences, of this superfluid phase are discussed. A quantum phase

transition to the normal state is predicted at the BCS sides of two resonances,

and the phase separation instability is also discussed.

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

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\\

Paper: cond-mat/0607463

Date: Wed, 19 Jul 2006 00:32:08 GMT (14kb)

Title: Quantum insulating states of F=2 cold atoms in optical lattices

Authors: Fei Zhou and Gordon W. Semenoff (PITP and UBC)

Comments: 4 pages, 1 figure included

Subj-class: Other

\\

In this Letter we study various spin correlated insulating states of F=2 cold

atoms in optical lattices. We find that the effective spin exchange interaction

due to virtual hopping contains an {\em octopole} coupling between two

neighboring lattice sites. Depending on scattering lengths and numbers of

particles per site the ground states are either rotationally invariant dimer or

trimer Mott insulators or insulating states with various spin orders. Three

spin ordered insulating phases are ferromagnetic, cyclic and nematic Mott

insulators. We estimate the phase boundaries for states with different numbers

of atoms per lattice site.

\\ ( http://arXiv.org/abs/cond-mat/0607463 , 14kb)

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\\

Paper: cond-mat/0607464

Date: Wed, 19 Jul 2006 01:19:23 GMT (297kb)

Title: States of fermionic atoms in an optical superlattice across a Feshbach

resonance

Authors: T. Goodman and L.-M. Duan

Comments: 10 pages, 11 figures

Subj-class: Other

\\

We investigate states of fermionic atoms across a broad Feshbach resonance in

an optical superlattice which allows interaction only among a small number of

lattice sites. The states are in general described by superpositions of atomic

resonating valence bonds and dressed molecules. As one scans the magnetic

field, level crossing is found between states with different symmetry

properties, which may correspond to a quantum phase transition in the many-body

case.

\\ ( http://arXiv.org/abs/cond-mat/0607464 , 297kb)

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\\

Paper: cond-mat/0607465

Date: Wed, 19 Jul 2006 01:42:36 GMT (181kb)

Title: Modulated Bose-Einstein Condensate in BaCuSi2O6

Authors: Ch. R\"uegg, D.F. McMorrow, B. Normand, H.M. Ronnow, S.E. Sebastian,

I.R. Fisher, C.D. Batista, S. Gvasaliya, Ch. Niedermayer, J. Stahn

Comments: 5 pages, 4 figures

Subj-class: Strongly Correlated Electrons

\\

The compound BaCuSi2O6 is a quantum magnet with antiferromagnetic dimers of S

= 1/2 moments on a quasi-2D square lattice. We have investigated its spin

dynamics by inelastic neutron scattering experiments on single crystals with an

energy resolution considerably higher than in an earlier study. We observe

multiple magnon modes, indicating clearly that the magnetic Hamiltonian is more

complex than previously understood. Inequivalent dimer sites lead to a distinct

form of magnon Bose-Einstein condensate (BEC) with a spatially modulated

condensate amplitude.

\\ ( http://arXiv.org/abs/cond-mat/0607465 , 181kb)

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\\

Paper: cond-mat/0607476

Date: Wed, 19 Jul 2006 08:35:00 GMT (16kb)

Title: Co-existence and shell structures of several superfluids in trapped

three-component Fermi mixtures

Authors: T. Paananen, P. Torma, and J.-P. Martikainen

Comments: 4 pages, 4 figures

Subj-class: Superconductivity

\\

We study the properties of a trapped interacting three component Fermi gas.

We assume that one of the components can have a different mass from the other

two. We calculate the different phases of the three component mixture and find

a rich variety of different phases corresponding to different pairing channels,

and simple ways of tuning the system from one phase to another. In particular,

we predict co-existence of several different superfluids in the trap, forming a

shell structure, and phase transitions from this mixture of superfluids to a

single superfluid when the system parameters or temperature is varied. Such

shell structures realize superfluids with a non-trivial spatial topology and

leave clear observable signatures in the density profile of the gas.

\\ ( http://arXiv.org/abs/cond-mat/0607476 , 16kb)

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\\

Paper: cond-mat/0607490

Date: Wed, 19 Jul 2006 14:17:46 GMT (23kb)

Title: Time-dependent multi-orbital mean-field for fragmented Bose-Einstein

condensates

Authors: O. E. Alon, A. I. Streltsov, and L. S. Cederbaum

Comments: 16 pages, 1 figure

Subj-class: Other

\\

The evolution of Bose-Einstein condensates is usually described by the famous

time-dependent Gross-Pitaevskii equation, which assumes all bosons to reside in

a single time-dependent orbital. In the present work we address the evolution

of fragmented condensates, for which two (or more) orbitals are occupied, and

derive a corresponding time-dependent multi-orbital mean-field theory. We call

our theory TDMF($n$), where $n$ stands for the number of evolving fragments.

Working equations for a general two-body interaction between the bosons are

explicitly presented along with an illustrative numerical example.

\\ ( http://arXiv.org/abs/cond-mat/0607490 , 23kb)

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\\

Paper: cond-mat/0607491

Date: Wed, 19 Jul 2006 14:30:04 GMT (142kb)

Title: Collective modes as a probe of the equation of state for partially

polarized Fermi gases

Authors: Theja N. De Silva, Erich J. Mueller

Comments: 4 pages, 2 figures

Subj-class: Other

\\

We calculate the collective modes of a partially polarized Fermi gas trapped

in a spherically symmetric harmonic potential. We show that the breathing mode

frequency exhibits non-monotonic dependence on polarization in the entire

BCS-BEC crossover region. Moreover, we find that the breathing mode can be used

to distinguish between two commonly used unitary gas equations of state.

\\ ( http://arXiv.org/abs/cond-mat/0607491 , 142kb)

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\\

Paper: cond-mat/0607493

Date: Wed, 19 Jul 2006 15:00:53 GMT (162kb)

Title: Collective mode of homogeneous superfluid Fermi gases in the BEC-BCS

crossover

Authors: R. Combescot, M.Yu. Kagan and S. Stringari

Comments: 21 pages

Subj-class: Other

\\

We perform a detailed study of the collective mode across the whole BEC-BCS

crossover in fermionic gases at zero temperature, covering the whole range of

energy beyond the linear regime. This is done on the basis of the dynamical BCS

model. We recover first the results of the linear regime in a simple form. Then

specific attention is payed to the non linear part of the dispersion relation

and its interplay with the continuum of single fermionic excitations. In

particular we consider in detail the merging of collective mode into the

continuum of single fermionic excitations. This occurs not only on the BCS side

of the crossover, but also slightly beyond unitarity on the BEC side. Another

remarkable feature is the very linear behaviour of the dispersion relation in

the vicinity of unitarity almost up to merging with the continuum. Finally,

while on the BEC side the mode is quite analogous to the Bogoliubov mode, a

difference appear at high wavevectors. On the basis of our results we determine

the Landau critical velocity in the BEC-BCS crossover which is found to be

largest close to unitarity. Our investigation has revealed interesting

qualitative features which would deserve experimental exploration as well as

further theoretical studies by more sophisticated means.

\\ ( http://arXiv.org/abs/cond-mat/0607493 , 162kb)

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\\

Paper: cond-mat/0512628

replaced with revised version Wed, 19 Jul 2006 18:45:49 GMT (84kb)

Title: Effective field theory of boson-fermion mixtures and bound fermion

states on a vortex of boson superfluid

Authors: Yusuke Nishida and Dam Thanh Son

Comments: 14 pages, 4 figures, revtex4; typos corrected, references added,

version to appear in Phys. Rev. A

Report-no: INT-PUB 05-31, TKYNT-05-31

Subj-class: Other

Journal-ref: Phys. Rev. A 74, 013615 (2006)

DOI: 10.1103/PhysRevA.74.013615

\\ ( http://arXiv.org/abs/cond-mat/0512628 , 84kb)

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\\

Paper: cond-mat/0603340

replaced with revised version Wed, 19 Jul 2006 08:10:21 GMT (25kb)

Title: Calogero-Sutherland gas of ultracold Bose atoms

Authors: Yue Yu

Comments: 4 pages,1 figure,update version

Subj-class: Other; Statistical Mechanics; Mathematical Physics

\\ ( http://arXiv.org/abs/cond-mat/0603340 , 25kb)

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\\

Paper: quant-ph/0607131

Date: Wed, 19 Jul 2006 19:03:59 GMT (290kb)

Title: Coherent acceleration of material wavepackets in modulated optical

fields

Authors: Farhan Saif and Pierre Meystre

\\

We study the quantum dynamics of a material wavepacket bouncing off a

modulated atomic mirror in the presence of a gravitational field. We find the

occurrence of coherent accelerated dynamics for atoms beyond the familiar

regime of dynamical localization. The acceleration takes place for certain

initial phase space data and within specific windows of modulation strengths.

The realization of the proposed acceleration scheme is within the range of

present day experimental possibilities.

\\ ( http://arXiv.org/abs/quant-ph/0607131 , 290kb)

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\\

Paper: cond-mat/0607503

Date: Wed, 19 Jul 2006 20:59:12 GMT (21kb)

Title: Collective Excitations of a Two-Component Bose Condensate at Finite

Temperature

Authors: C.-H. Zhang, H. A. Fertig

Comments: 4 pages, 3 figures, Submitted to PRL

Subj-class: Other

\\

We compare the collective modes for Bose-condensed systems with two

degenerate components with and without spontaneous intercomponent coherence at

finite temperature using the time-dependent Hartree-Fock approximation. We show

that the interaction between the condensate and non-condensate in these two

cases results in qualitatively different collective excitation spectra. We show

that at zero temperature the single-particle excitations of the incoherent Bose

condensate can be probed by intercomponent excitations.

\\ ( http://arXiv.org/abs/cond-mat/0607503 , 21kb)

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\\

Paper: cond-mat/0607519

Date: Thu, 20 Jul 2006 13:23:01 GMT (87kb)

Title: Energetics and structural properties of three-dimensional bosonic

clusters near threshold

Authors: G. J. Hanna, and D. Blume

Comments: 12 pages, 12 figures

Subj-class: Other

\\

We treat three-dimensional bosonic clusters wih up to N=40 atoms, interacting

additively through two-body Van der Waals potentials, in the near-threshold

regime. Our study inludes super-borromean systems with N atoms for which all

subsystems are unbound. We determine the energetics and structural properties

as the expectation value of the interparticle distance as a function of the

coupling strength. It has been shown that the coupling strength g*(N), for

which the N-body systems becomes unbound, is bounded by the coupling constant

g*(N-1) for which the next smaller system with N-1 atoms becomes unbound, i.e.,

g*(N) >= (N-1)/Ng*(N-1). By fitting our numerically determined ground state

energies to a simple functional form with three fitting parameters, we

determine the relationship between g*(N) and g*(N-1). Our trimer and tetramer

energies fall on the so-called Tjon line, which has been studied in nuclear

physics. We confirm the existence of generalized Tjon lines for larger

clusters. Signatures of the universal behavior of weakly-bound

three-dimensional clusters can possibly be observed in ultracold Bose gases.

\\ ( http://arXiv.org/abs/cond-mat/0607519 , 87kb)

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\\

Paper: cond-mat/0603838

replaced with revised version Thu, 20 Jul 2006 01:17:03 GMT (634kb)

Title: Modulation instability and solitary wave formation in two-component

Bose-Einstein condensates

Authors: Kenichi Kasamatsu, Makoto Tsubota

Comments: 15 pages, 10 figures

Subj-class: Other

Journal-ref: Phys. Rev. A 74, 013617 (2006)

\\ ( http://arXiv.org/abs/cond-mat/0603838 , 634kb)

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\\

Paper: cond-mat/0606319

replaced with revised version Thu, 20 Jul 2006 15:08:42 GMT (15kb)

Title: Off-diagonal correlations of lattice impenetrable bosons in one

dimension

Authors: D.M. Gangardt, G.V. Shlyapnikov

Comments: 10 pages. Submitted to the Focus Issue on 'Cold Atoms in Optical

Lattices' of New Journal of Physics

Subj-class: Statistical Mechanics

\\ ( http://arXiv.org/abs/cond-mat/0606319 , 15kb)

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\\

Paper: physics/0607183

Date: Thu, 20 Jul 2006 18:19:17 GMT (23kb)

Title: Football: A Naive Approximation to the Effect of Increasing Goal Size on

the Number of Goals

Authors: J. Mira

Comments: 4 pages

Subj-class: Physics and Society; Popular Physics

\\

The effect of increasing goal mouth size on the number of goals scored in a

football match is discussed in a very preliminary and simple way, considering

elastic collisions of the ball with the posts. The result is obtained on the

basis of data taken from the Spanish Professional League, that show a high

number of shots-to-post. Surprisingly, there is a direct correlation of the

increase in goal mouth area with the increase of goals.

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\\

Paper: cond-mat/0607542

Date: Fri, 21 Jul 2006 07:01:35 GMT (25kb)

Title: Analytic solution of the 1D finite coupling delta function Bose gas

Authors: P. J. Forrester, N. E. Frankel and M. I. Makin

Comments: 23 pages, 0 figures, uses rotate.sty

Subj-class: Statistical Mechanics

\\

An intensive study for both the weak coupling and strong coupling limits of

the ground state properties of this classic system is presented. Detailed

results for specific values of finite $N$ are given and from them results for

general $N$ are determined. We focus on the density matrix and concomitantly

its Fourier transform, the occupation numbers, along with the pair correlation

function and concomitantly its Fourier transform, the structure factor. These

are the signature quantities of the Bose gas. One specific result is that for

weak coupling a rational polynomial structure holds despite the transcendental

nature of the Bethe equations. All these new results are predicated on the

Bethe ansatz and are built upon the seminal works of the past.

\\ ( http://arXiv.org/abs/cond-mat/0607542 , 25kb)

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\\

Paper: cond-mat/0607546

Date: Fri, 21 Jul 2006 10:21:21 GMT (13kb)

Title: Bose Condensed Gas in Strong Disorder Potential With Arbitrary

Correlation Length

Authors: Patrick Navez, Axel Pelster, Robert Graham

Comments: Author information under

http://www.theo-phys.uni-essen.de/tp/ags/pelster_dir

Subj-class: Disordered Systems and Neural Networks

\\

We study the properties of a dilute Bose condensed gas at zero temperature in

the presence of a strong random potential with arbitrary correlation length.

Starting from the underlying Gross-Pitaevskii equation, we use the random phase

approximation in order to get a closed integral equation for the averaged

density distribution which allows to determine both the condensate and the

superfluid density. The obtained results generalize those of Huang and Meng

(HM) to strong disorder. In particular, we find the critical value of the

disorder strength, where the superfluid phase disappears by a first-order phase

transition. We show how this critical value changes as a function of the

correlation length.

\\ ( http://arXiv.org/abs/cond-mat/0607546 , 13kb)

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\\

Paper: cond-mat/0607556

Date: Fri, 21 Jul 2006 14:52:29 GMT (21kb)

Title: Interferences in the density of two initially independent Bose-Einstein

condensates

Authors: L. S. Cederbaum, A. I. Streltsov, Y. B. Band, and O. E. Alon

Comments: 13 pages, 2 figures

Subj-class: Other

\\

It is shown that the density of two {\it initially independent} condensates

which are allowed to expand and overlap can show interferences as a function of

time due to interparticle interaction. Using many-body theory, explicit

expressions for the density are given which are exact in the weak interaction

limit. General working equations are discussed which reproduce exactly the

density in this limit. Illustrative examples are presented.

\\ ( http://arXiv.org/abs/cond-mat/0607556 , 21kb)

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\\

Paper: cond-mat/0607558

Date: Fri, 21 Jul 2006 15:09:34 GMT (269kb)

Title: Quantum resonances and rectification of driven cold atoms in optical

lattices

Authors: S. Denisov, L. Morales-Molina, and S. Flach

Comments: 4 pages, 4 figures

Subj-class: Statistical Mechanics

\\

Classical Hamiltonian ratchets have been recently successfully realized using

cold atoms in driven optical lattices. Here we study the current rectification

of the motion of a quantum particle in a periodic potential exposed to an

external ac field. The dc current appears due to the desymmetrization of

Floquet eigenstates, which become transporting. Quantum dynamics enhances the

dependence of the current on the initial phase of the driving field. By

changing the laser field parameters which control the degree of space-time

asymmetry, Floquet eigenstates are tuned through avoided crossings. These

quantum resonances induce resonant changes of the resulting current. The width,

strength and position of these quantum resonances are tunable using control

parameters of the experimental realization with cold atoms.

\\ ( http://arXiv.org/abs/cond-mat/0607558 , 269kb)

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

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/ ========================================================================= 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 Tue Jul 25 2006 - 02:18:55 EST

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