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

Date: Sat, 6 Oct 2007 22:07:09 +1000 (EST)

Date: Sat, 6 Oct 2007 22:07:09 +1000 (EST)

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

Hi everyone,

All sorts of circumstances over the past four weeks that I won't go into have

gotten in the way of this email, but hopefully a more normal service will

resume in short order. I haven't stopped just yet!

In the week that this email covers, there are 26 new preprints and 10

replacements.

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arXiv:0708.4304

Date: Fri, 31 Aug 2007 09:31:00 GMT (463kb,D)

Title: Control of atomic currents using a quantum stirring device

Authors: Moritz Hiller, Tsampikos Kottos, Doron Cohen

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

Comments: 5 pages, 4 figures

\\

We propose a BEC stirring device which can be regarded as the incorporation

of a quantum pump into a closed circuit: it produces a DC circulating current

in response to a cyclic adiabatic change of two control parameters of an

optical trap. We demonstrate the feasibility of this concept and point out that

such device can be utilized in order to probe the interatomic interactions.

\\ ( http://arxiv.org/abs/0708.4304 , 463kb)

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arXiv:0709.0012

Date: Fri, 31 Aug 2007 20:53:42 GMT (257kb)

Title: Observation of persistent flow of a Bose-Einstein condensate in a

toroidal trap

Authors: C. Ryu, M. F. Andersen, P. Clade, Vasant Natarajan, K. Helmerson, W.

D. Phillips

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

Comments: 1 file, 5 figures

\\

We have observed the persistent flow of Bose-condensed atoms in a toroidal

trap. The flow persists without decay for up to 10 s, limited only by

experimental factors such as drift and trap lifetime. The quantized rotation

was initiated by transferring one unit, $\hbar$, of the orbital angular

momentum from Laguerre-Gaussian photons to each atom. Stable flow was only

possible when the trap was multiply-connected, and was observed with a BEC

fraction as small as 15%. We also created flow with two units of angular

momentum, and observed its splitting into two singly-charged vortices when the

trap geometry was changed from multiply- to simply-connected.

\\ ( http://arxiv.org/abs/0709.0012 , 257kb)

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\\

arXiv:0709.0149

Date: Mon, 3 Sep 2007 03:56:02 GMT (10kb)

Title: Blackbody radiation shift in a 43Ca+ ion optical frequency standard

Authors: Bindiya Arora, M. S. Safronova, and Charles W. Clark

Categories: quant-ph

Comments: 4 pages

\\

Motivated by the prospect of an optical frequency standard based on 43Ca+, we

calculate the blackbody radiation (BBR) shift of the 4s_1/2-3d_5/2 clock

transition, which is a major component of the uncertainty budget. The

calculations are based on the relativistic all-order single-double method where

all single and double excitations of the Dirac-Fock wave function are included

to all orders of perturbation theory. Additional calculations are conducted for

the dominant contributions in order to evaluate some omitted high-order

corrections and estimate the uncertainties of the final results. The BBR shift

obtained for this transition is 0.38(1) Hz. The tensor polarizability of the

3d_5/2 level is also calculated and its uncertainty is evaluated as well. Our

results are compared with other calculations.

\\ ( http://arxiv.org/abs/0709.0149 , 10kb)

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\\

arXiv:0709.0212

Date: Mon, 3 Sep 2007 12:32:54 GMT (10kb)

Title: Generation of non-critically squeezed light via spontaneous rotational

symmetry breaking

Authors: Carlos Navarrete-Benlloch, Eugenio Roldan, and German J. de Valcarcel

Categories: quant-ph

Comments: 4 pages, no figures

\\

We theoretically address the generation of squeezed light through the

spontaneous breaking of rotational invariance that occurs in a two-mode

degenerate optical parametric oscillator (DOPO) pumped above threshold. In

particular, we show that a DOPO with spherical mirrors in which the signal and

idler fields, which are degenerate in frequency and polarization, correspond to

first order Gauss-Laguerre modes, produces a perfectly squeezed vacuum, within

the linearized theory, at any pumping level above threshold. Hence the

phenomenon is non-critical.

\\ ( http://arxiv.org/abs/0709.0212 , 10kb)

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\\

arXiv:0708.4056 (*cross-listing*)

Date: Thu, 30 Aug 2007 02:34:24 GMT (86kb)

Title: Renormalization group analysis of resonantly interacting anyons

Authors: Yusuke Nishida

Categories: hep-th cond-mat.other nucl-th quant-ph

Comments: 5 pages, 5 figures

Report-no: INT-PUB 07-20

\\

We formulate a field theory for resonantly interacting anyons, which enables

us to perform a perturbative calculation near the fermionic limit. We derive

renormalization group equations for three-body and four-body couplings at

one-loop order. In addition to two fixed points, we find a limit cycle behavior

in the four-body coupling, which implies an infinite set of bound states in the

four anyon system.

\\ ( http://arxiv.org/abs/0708.4056 , 86kb)

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\\

arXiv:0709.0014

Date: Fri, 31 Aug 2007 21:19:22 GMT (10kb)

Title: Accurate determination of electric-dipole matrix elements in K and Rb

from Stark shift measurements

Authors: Bindiya Arora, M. S. Safronova, and Charles W. Clark

Categories: physics.atom-ph

Comments: 5 pages

\\

Stark shifts of potassium and rubidium D1 lines have been measured with high

precision by Miller et al [1]. In this work, we combine these measurements with

our all-order calculations to determine the values of the electric-dipole

matrix elements for the 4p_j-3d_j' transitions in K and for the 5p_j-4d_j'

transitions in Rb to high precision. The 4p_1/2-3d_3/2 and 5p_1/2-4d_3/2

transitions contribute on the order of 90% to the respective polarizabilities

of the np_1/2 states in K and Rb, and the remaining 10% can be accurately

calculated using the relativistic all-order method. Therefore, the combination

of the experimental data and theoretical calculations allows us to determine

the np-(n-1)d matrix elements and their uncertainties. We compare these values

with our all-order calculations of the np-(n-1)d matrix elements in K and Rb

for a benchmark test of the accuracy of the all-order method for transitions

involving nd states. Such matrix elements are of special interest for many

applications, such as determination of magic wavelengths in alkali-metal atoms

for state-insensitive cooling and trapping and determination of blackbody

radiation shifts in optical frequency standards with ions.

\\ ( http://arxiv.org/abs/0709.0014 , 10kb)

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\\

arXiv:0709.0130

Date: Sun, 2 Sep 2007 21:26:16 GMT (52kb)

Title: Magic wavelengths for the np-ns transitions in alkali-metal atoms

Authors: Bindiya Arora, M. S. Safronova, and Charles W. Clark

Categories: physics.atom-ph

Comments: 12 pages, 8 figures

\\

Extensive calculations of the electric-dipole matrix elements in alkali-metal

atoms are conducted using the relativistic all-order method. This approach is a

linearized version of the coupled-cluster method, which sums infinite sets of

many-body perturbation theory terms. All allowed transitions between the lowest

ns, np_1/2, np_3/2 states and a large number of excited states are considered

in these calculations and their accuracy is evaluated. The resulting

electric-dipole matrix elements are used for the high-precision calculation of

frequency-dependent polarizabilities of the excited states of alkali-metal

atoms. We find magic wavelengths in alkali-metal atoms for which the ns and

np_1/2 and np_3/2 atomic levels have the same ac Stark shifts, which

facilitates state-insensitive optical cooling and trapping.

\\ ( http://arxiv.org/abs/0709.0130 , 52kb)

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arXiv:0709.0359

Date: Tue, 4 Sep 2007 08:15:22 GMT (125kb)

Title: Adiabatic Fidelity for Atom-Molecule Conversion in a Nonlinear

Three-Level $\Lambda$-system

Authors: Shao-Ying Meng, Li-Bin Fu, Jie Liu

Categories: cond-mat.other

Comments: 4 pages, 5 figures

\\

We investigate the dynamics of the population transfer for atom-molecule

three-level $\Lambda$-system on stimulated Raman adiabatic passage(STIRAP). We

find that the adiabatic fidelity for the coherent population trapping(CPT)

state or dark state, as the function of the adiabatic parameter, approaches to

unit in a power law. The power exponent however is much less than the

prediction of linear adiabatic theorem. We further discuss how to achieve

higher adiabatic fidelity for the dark state through optimizing the external

parameters of STIRAP. Our discussions are helpful to gain higher atom-molecule

conversion yield in practical experiments.

\\ ( http://arxiv.org/abs/0709.0359 , 125kb)

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\\

arXiv:0709.0362

Date: Tue, 4 Sep 2007 08:29:58 GMT (230kb)

Title: Non-perturbative renormalization-group approach to zero-temperature Bose

systems

Authors: N. Dupuis and K. Sengupta

Categories: cond-mat.other

Comments: 6 pages, 8 figures

\\

We use a non-perturbative renormalization-group technique to study

interacting bosons at zero temperature. Our approach reveals the instability of

the Bogoliubov fixed point when $d\leq 3$ and yields the exact infrared

behavior in all dimensions $d>1$ within a rather simple theoretical framework.

It also enables to compute the low-energy properties in terms of the parameters

of a microscopic model. In one-dimension and for not too strong interactions,

it yields a good picture of the Luttinger-liquid behavior of the superfluid

phase.

\\ ( http://arxiv.org/abs/0709.0362 , 230kb)

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arXiv:0709.0368

Date: Tue, 4 Sep 2007 09:05:18 GMT (20kb)

Title: Vortex spectrum in superfluid turbulence: interpretation of a recent

experiment

Authors: Philippe-Emmanuel P.-E. Roche (NEEL), Carlo F. Barenghi

Categories: cond-mat.other

Comments: Submitted for publication

http://crtbt.grenoble.cnrs.fr/helio/GROUP/infa.html

http://www.mas.ncl.ac.uk/~ncfb/

Proxy: ccsd hal-00169495

\\

We discuss a recent experiment in which the spectrum of the vortex line

density fluctuations has been measured in superfluid turbulence. The observed

frequency dependence of the spectrum, $f^{-5/3}$, disagrees with classical

vorticity spectra if, following the literature, the vortex line density is

interpreted as a measure of the vorticity or enstrophy. We argue that the

disagrement is solved if the vortex line density field is decomposed into a

polarised field (which carries most of the energy) and an isotropic field

(which is responsible for the spectrum).

\\ ( http://arxiv.org/abs/0709.0368 , 20kb)

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\\

arXiv:0709.0388

Date: Tue, 4 Sep 2007 10:34:34 GMT (626kb)

Title: Effects of a Fluctuating Interface between a Superfluid and a Polarized

Fermi Gas

Authors: Hui Zhai and Dung-Hai Lee

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

Comments: 4 pages, 3 figures

\\

Motivated by recent experiments in trapped Fermi gas with spin population

imbalance, we discuss the effects of the quantum and thermal fluctuations of

the interface between a fully paired superfluid core and a fully polarized

Fermi gas. We demonstrate that even if there is no true partially polarized

thermodynamic phase in bulk, the interface fluctuation can give rise to a

partially polarized transition regime in trap. Our theory yields a definite

prediction for the functional forms of the spatial profile of spin polarization

and pairing gap, and we show that the spin-resolved density profiles measured

by both the MIT and Rice groups obey this function form. We also show that

sufficient large fluctuation will lead to a visibly unequal density even at the

center of the cloud. We hope this picture can shed lights on the controversial

discrepancies in recent experiments.

\\ ( http://arxiv.org/abs/0709.0388 , 626kb)

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arXiv:0709.0405

Date: Tue, 4 Sep 2007 12:12:08 GMT (17kb)

Title: Metastability of persistent currents in trapped gases of atoms

Authors: K. Karkkainen (1), J. Christensson (1), G. Reinisch (2), G. M.

Kavoulakis (1), S. M. Reimann (1) ((1) LTH, Lund, (2) Nice)

Categories: cond-mat.other

Comments: 7 pages, RevTex, 5 figures

\\

We examine the conditions that give rise to metastable, persistent currents

in a trapped Bose-Einstein condensate. A necessary condition for the stability

of persistent currents is that the trapping potential is not a monotonically

increasing function of the distance from the trap center. Persistent currents

also require that the interatomic interactions are sufficiently strong and

repulsive. Finally, any off-center vortex state is shown to be unstable, while

a driven gas shows hysteresis.

\\ ( http://arxiv.org/abs/0709.0405 , 17kb)

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\\

arXiv:0709.0499

Date: Tue, 4 Sep 2007 18:48:24 GMT (116kb)

Title: Scattering Models for Ultracold Atoms

Authors: Eric Braaten, Masaoki Kusunoki and Dongqing Zhang

Categories: cond-mat.other

Comments: 60 pages, 6 figures

\\

We present a review of scattering models that can be used to describe the

low-energy behavior of identical bosonic atoms. In the simplest models, the

only degrees of freedom are atoms in the same spin state. More elaborate models

have other degrees of freedom, such as atoms in other spin states or diatomic

molecules. The parameters of the scattering models are specified by giving the

S-wave phase shifts for scattering of atoms in the spin state of primary

interest. The models are formulated as local quantum field theories and the

renormalization of their coupling constants is determined. Some of the

parameters can be constrained by renormalizability or by the absence of

negative-norm states. The Green's functions that describe the evolution of

two-atom states are determined analytically. They are used to determine the

T-matrix elements for atom-atom scattering and the binding energies of diatomic

molecules. The scattering models all exhibit universal behavior as the

scattering length in a specific spin state becomes large.

\\ ( http://arxiv.org/abs/0709.0499 , 116kb)

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\\

arXiv:0709.0343

Date: Tue, 4 Sep 2007 07:28:34 GMT (670kb)

Title: Exactly-solvable coupled-channel potential models of atom-atom magnetic

Feshbach resonances from supersymmetric quantum mechanics

Authors: Andrey M. Pupasov, Boris F. Samsonov, Jean-Marc Sparenberg

Categories: quant-ph

Comments: 19 pages, 15 figures

\\

Starting from a system of $N$ radial Schr\"odinger equations with a vanishing

potential and finite threshold differences between the channels, a coupled $N

\times N$ exactly-solvable potential model is obtained with the help of a

single non-conservative supersymmetric transformation. The obtained potential

matrix, which subsumes a result obtained in the literature, has a compact

analytical form, as well as its Jost matrix. It depends on $N (N+1)/2$

unconstrained parameters and on one upper-bounded parameter, the factorization

energy. A detailed study of the model is done for the $2\times 2$ case: a

geometrical analysis of the zeros of the Jost-matrix determinant shows that the

model has 0, 1 or 2 bound states, and 0 or 1 resonance; the potential

parameters are explicitly expressed in terms of its bound-state energies, of

its resonance energy and width, or of the open-channel scattering length, which

solves schematic inverse problems. As a first physical application,

exactly-solvable $2\times 2$ atom-atom interaction potentials are constructed,

for cases where a magnetic Feshbach resonance interplays with a bound or

virtual state close to threshold, which results in a large background

scattering length.

\\ ( http://arxiv.org/abs/0709.0343 , 670kb)

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\\

arXiv:0709.0352

Date: Tue, 4 Sep 2007 07:55:18 GMT (78kb)

Title: Macroscopic Entanglement of a Bose Einstein Condensate on a

Superconducting Atom Chip

Authors: Mandip Singh

Categories: quant-ph

Comments: 4 Pages, Two figures

\\

We propose and analyse a practically implementable scheme to generate

macroscopic entanglement of a Bose-Einstein condensate in a micro-magnetic trap

magnetically coupled to a superconducting loop. We treat the superconducting

loop in a quantum superposition of two different flux states coupled with the

magnetic trap to generate macroscopic entanglement. Our scheme also provides a

platform to realise interferometry of entangled atoms through the Bose-Einstein

condensate and to explore physics at the quantum-classical interface.

\\ ( http://arxiv.org/abs/0709.0352 , 78kb)

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\\

arXiv:0709.0527

Date: Tue, 4 Sep 2007 20:13:07 GMT (564kb,D)

Title: Quantum Non-Demolition Detection of Strongly Correlated Systems

Authors: Kai Eckert, Oriol Romero-Isart, Mirta Rodriguez, Maciej Lewenstein,

Eugene S. Polzik and Anna Sanpera

Categories: cond-mat.other

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

submitted version

\\

Preparation, manipulation, and detection of strongly correlated states of

quantum many body systems are among the most important goals and challenges of

modern physics. Ultracold atoms offer an unprecedented playground for

realization of these goals. Here we show how strongly correlated states of

ultracold atoms can be detected in a quantum non-demolition scheme, that is, in

the fundamentally least destructive way permitted by quantum mechanics. In our

method, spatially resolved components of atomic spins couple to quantum

polarization degrees of freedom of light. In this way quantum correlations of

matter are faithfully mapped on those of light; the latter can then be

efficiently measured using homodyne detection. We illustrate the power of such

spatially resolved quantum noise limited polarization measurement by applying

it to detect various standard and "exotic" types of antiferromagnetic order in

lattice systems and by indicating the feasibility of detection of superfluid

order in Fermi liquids.

\\ ( http://arxiv.org/abs/0709.0527 , 564kb)

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\\

arXiv:0709.0605

Date: Wed, 5 Sep 2007 13:58:59 GMT (518kb)

Title: AC-induced superfluidity

Authors: Andre Eckardt and Martin Holthaus

Categories: cond-mat.other

Comments: 6 pages, 4 figures

\\

We argue that a system of ultracold bosonic atoms in a tilted optical lattice

can become superfluid in response to resonant AC forcing. Among others, this

allows one to prepare a Bose-Einstein condensate in a state associated with a

negative effective mass. Our reasoning is backed by both exact numerical

simulations for systems consisting of few particles, and by a theoretical

approach based on Floquet-Fock states.

\\ ( http://arxiv.org/abs/0709.0605 , 518kb)

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\\

arXiv:0709.0656

Date: Wed, 5 Sep 2007 14:00:02 GMT (900kb)

Title: Hidden Fermi Liquid: The Secret of High Tc Cuprates

Authors: Philip W Anderson

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

\\

I present a formalism for dealing directly with the effects of the Gutzwiller

projection, which is implicit in the t-J model widely believed to underly the

phenomenology of the high-Tc cuprates. I suggest that a true BCS condensation

from a Fermi liquid state takes place, but in the unphysical space prior to

projection. The theory which results upon projection does not follow

conventional rules of diagram theory and in fact in the normal state is a Z=0

non-Fermi liquid. Anomalous properties of this strange metal normal state are

predicted and compared to experiments.

\\ ( http://arxiv.org/abs/0709.0656 , 900kb)

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arXiv:0709.0698

Date: Wed, 5 Sep 2007 16:39:22 GMT (192kb)

Title: Probing two-fluid hydrodynamics in a trapped Fermi superfluid at

unitarity

Authors: Edward Taylor, Hui Hu, Xia-Ji Liu, Allan Griffin

Categories: cond-mat.other

Comments: 5 pages, 3 figures

\\

We develop a variational approach to calculate the density response function

at finite temperatures of the lowest-lying two-fluid modes in a trapped

two-component Fermi superfluid close to a Feshbach resonance. The out-of-phase

oscillations, which are the analogue in trapped gases of second sound in

uniform superfluids, have so far not been observed in cold-atom experiments. We

show that these modes are observable via two-photon Bragg scattering, whose

spectrum is proportional to the imaginary part of density response function. We

predict pronounced peaks for the out-of-phase modes in the Bragg scattering

spectrum at unitarity at finite temperatures. This provides strong evidence for

superfluidity at unitarity and a promising way to probe the unitarity equation

of state.

\\ ( http://arxiv.org/abs/0709.0698 , 192kb)

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\\

arXiv:0709.0613

Date: Wed, 5 Sep 2007 10:29:24 GMT (14kb)

Title: Complementarity and uncertainty relations for matter wave interferometry

Authors: K.-P. Marzlin, B. C. Sanders, and P. L. Knight

Categories: quant-ph

Comments: four pages, one figure

\\

We provide a rigorous quantitative connection between the complementarity

relations of path information vs fringe visibility for a particle in an

interferometer and uncertainty relations between position and modular momentum.

This theory is applied to atom interferometry wherein spontaneously emitted

photons can provide path information, and we show that the metamaterial

`perfect lens' enables atom interferometry to reach an extremum of this

complementarity trade-off.

\\ ( http://arxiv.org/abs/0709.0613 , 14kb)

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\\

arXiv:0709.0716

Date: Wed, 5 Sep 2007 17:49:31 GMT (47kb)

Title: Maximum Entanglement in Squeezed Boson and Fermion States

Authors: F.C. Khanna, J.M.C. Malbouisson, A.E. Santana, E.S. Santos

Categories: quant-ph

Comments: 4 pages

Journal-ref: Phys. Rev A {\bf 76}, 022109 (2007)

DOI: 10.1103/PhysRevA.76.022109

\\

A class of squeezed boson and fermion states is studied with particular

emphasis on the nature of entanglement. We first investigate the case of

bosons, considering two-mode squeezed states. Then we construct the fermion

version to show that such states are maximum entangled, for both bosons and

fermions. To achieve these results, we demonstrate some relations involving

squeezed boson states. The generalization to the case of fermions is made by

using Grassmann variables.

\\ ( http://arxiv.org/abs/0709.0716 , 47kb)

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\\

arXiv:0709.0817

Date: Thu, 6 Sep 2007 10:08:42 GMT (21kb)

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

radio-frequency spectra of ultracold Fermi atoms

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

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

Comments: 4 pages, 3 figures

\\

The radio-frequency spectra of ultracold Fermi atoms are calculated by

including final-state interactions affecting the excited level of the

transition, and compared quantitatively with the experimental data. This

inclusion reveals a competition between pairing-gap effects which tend to push

the oscillator strength toward high frequencies away from threshold, and

final-state effects which tend instead to pull the oscillator strength toward

threshold. As a result of this competition, the position of the peak of the

spectra cannot be simply related to the value of the pairing gap, whose

extraction thus requires support from theoretical calculations.

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

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\\

arXiv:0709.0895

Date: Thu, 6 Sep 2007 15:49:48 GMT (207kb,D)

Title: Vortex nucleation in Bose-Einstein Condensates subject to light induced

effective magnetic fields

Authors: D. R. Murray, P \"Ohberg, Dami\'a Gomila and Stephen M. Barnett

Categories: cond-mat.other

Comments: 7 pages, 7 figures

\\

We numerically simulate vortex nucleation in a Bose-Einstein Condensate (BEC)

subject to an effective magnetic field. The effective magnetic field is

generated from the interplay between light with a non-trivial phase structure

and the BEC, and can be shaped and controlled by appropriate modifications to

the phase and intensity of the light. We demonstrate that the nucleation of

vortices is seeded by instabilities in surface excitations which are coupled to

by an asymmetric trapping potential (similar to the case of condensates subject

to mechanical rotation) and show that this picture also holds when the applied

effective magnetic field is not homogeneous. The eventual configuration of

vortices in the cloud depends on the geometry of the applied field.

\\ ( http://arxiv.org/abs/0709.0895 , 207kb)

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\\

arXiv:0708.4304 (*cross-listing*)

Date: Fri, 31 Aug 2007 09:31:00 GMT (463kb,D)

Title: Control of atomic currents using a quantum stirring device

Authors: Moritz Hiller, Tsampikos Kottos, Doron Cohen

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

Comments: 5 pages, 4 figures

\\

We propose a BEC stirring device which can be regarded as the incorporation

of a quantum pump into a closed circuit: it produces a DC circulating current

in response to a cyclic adiabatic change of two control parameters of an

optical trap. We demonstrate the feasibility of this concept and point out that

such device can be utilized in order to probe the interatomic interactions.

\\ ( http://arxiv.org/abs/0708.4304 , 463kb)

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\\

arXiv:0709.0754

Date: Thu, 6 Sep 2007 16:51:51 GMT (951kb)

Title: Coherent Control of Trapped Bosons

Authors: Analabha Roy, Linda E. Reichl

Categories: physics.atom-ph

Comments: 17 figures

\\

We investigate the quantum behavior of a mesoscopic two-boson system produced

by number-squeezing ultracold gases of alkali metal atoms. The quantum Poincare

maps of the wavefunctions are affected by chaos in those regions of the phase

space where the classical dynamics produces features that are comparable to

hbar. We also investigate the possibility for quantum control in the dynamics

of excitations in these systems. Controlled excitations are mediated by pulsed

signals that cause Stimulated Raman Adiabatic passage (STIRAP) from the ground

state to a state of higher energy. The dynamics of this transition is affected

by chaos caused by the pulses in certain regions of the phase space. A

transition to chaos can thus provide a method of controlling STIRAP.

\\ ( http://arxiv.org/abs/0709.0754 , 951kb)

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\\

arXiv:0709.0827

Date: Thu, 6 Sep 2007 10:48:42 GMT (162kb)

Title: Sympathetic cooling in a mixture of diamagnetic and paramagnetic atoms

Authors: S. Tassy, N. Nemitz, F. Baumer, C. H\"ohl, A. Bat\"ar, A. G\"orlitz

Categories: physics.atom-ph

Comments: 4 pages, 4 figures

\\

We have experimentally realized a hybrid trap for ultracold paramagnetic

rubidium and diamagnetic ytterbium atoms by combining a bichromatic optical

dipole trap for ytterbium with a Ioffe-Pritchard-type magnetic trap for

rubidium. In this hybrid trap, sympathetic cooling of five different ytterbium

isotopes through elastic collisions with rubidium was achieved. A strong

dependence of the interspecies collisional cross section on the mass of the

ytterbium isotope was observed.

\\ ( http://arxiv.org/abs/0709.0827 , 162kb)

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The replacements:

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arXiv:0708.4304

Date: Fri, 31 Aug 2007 09:31:00 GMT (463kb,D)

Title: Control of atomic currents using a quantum stirring device

Authors: Moritz Hiller, Tsampikos Kottos, Doron Cohen

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

Comments: 5 pages, 4 figures

\\

We propose a BEC stirring device which can be regarded as the incorporation

of a quantum pump into a closed circuit: it produces a DC circulating current

in response to a cyclic adiabatic change of two control parameters of an

optical trap. We demonstrate the feasibility of this concept and point out that

such device can be utilized in order to probe the interatomic interactions.

\\ ( http://arxiv.org/abs/0708.4304 , 463kb)

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

\\

arXiv:0709.0012

Date: Fri, 31 Aug 2007 20:53:42 GMT (257kb)

Title: Observation of persistent flow of a Bose-Einstein condensate in a

toroidal trap

Authors: C. Ryu, M. F. Andersen, P. Clade, Vasant Natarajan, K. Helmerson, W.

D. Phillips

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

Comments: 1 file, 5 figures

\\

We have observed the persistent flow of Bose-condensed atoms in a toroidal

trap. The flow persists without decay for up to 10 s, limited only by

experimental factors such as drift and trap lifetime. The quantized rotation

was initiated by transferring one unit, $\hbar$, of the orbital angular

momentum from Laguerre-Gaussian photons to each atom. Stable flow was only

possible when the trap was multiply-connected, and was observed with a BEC

fraction as small as 15%. We also created flow with two units of angular

momentum, and observed its splitting into two singly-charged vortices when the

trap geometry was changed from multiply- to simply-connected.

\\ ( http://arxiv.org/abs/0709.0012 , 257kb)

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\\

arXiv:0709.0149

Date: Mon, 3 Sep 2007 03:56:02 GMT (10kb)

Title: Blackbody radiation shift in a 43Ca+ ion optical frequency standard

Authors: Bindiya Arora, M. S. Safronova, and Charles W. Clark

Categories: quant-ph

Comments: 4 pages

\\

Motivated by the prospect of an optical frequency standard based on 43Ca+, we

calculate the blackbody radiation (BBR) shift of the 4s_1/2-3d_5/2 clock

transition, which is a major component of the uncertainty budget. The

calculations are based on the relativistic all-order single-double method where

all single and double excitations of the Dirac-Fock wave function are included

to all orders of perturbation theory. Additional calculations are conducted for

the dominant contributions in order to evaluate some omitted high-order

corrections and estimate the uncertainties of the final results. The BBR shift

obtained for this transition is 0.38(1) Hz. The tensor polarizability of the

3d_5/2 level is also calculated and its uncertainty is evaluated as well. Our

results are compared with other calculations.

\\ ( http://arxiv.org/abs/0709.0149 , 10kb)

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

\\

arXiv:0709.0212

Date: Mon, 3 Sep 2007 12:32:54 GMT (10kb)

Title: Generation of non-critically squeezed light via spontaneous rotational

symmetry breaking

Authors: Carlos Navarrete-Benlloch, Eugenio Roldan, and German J. de Valcarcel

Categories: quant-ph

Comments: 4 pages, no figures

\\

We theoretically address the generation of squeezed light through the

spontaneous breaking of rotational invariance that occurs in a two-mode

degenerate optical parametric oscillator (DOPO) pumped above threshold. In

particular, we show that a DOPO with spherical mirrors in which the signal and

idler fields, which are degenerate in frequency and polarization, correspond to

first order Gauss-Laguerre modes, produces a perfectly squeezed vacuum, within

the linearized theory, at any pumping level above threshold. Hence the

phenomenon is non-critical.

\\ ( http://arxiv.org/abs/0709.0212 , 10kb)

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\\

arXiv:0708.4056 (*cross-listing*)

Date: Thu, 30 Aug 2007 02:34:24 GMT (86kb)

Title: Renormalization group analysis of resonantly interacting anyons

Authors: Yusuke Nishida

Categories: hep-th cond-mat.other nucl-th quant-ph

Comments: 5 pages, 5 figures

Report-no: INT-PUB 07-20

\\

We formulate a field theory for resonantly interacting anyons, which enables

us to perform a perturbative calculation near the fermionic limit. We derive

renormalization group equations for three-body and four-body couplings at

one-loop order. In addition to two fixed points, we find a limit cycle behavior

in the four-body coupling, which implies an infinite set of bound states in the

four anyon system.

\\ ( http://arxiv.org/abs/0708.4056 , 86kb)

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

\\

arXiv:0709.0014

Date: Fri, 31 Aug 2007 21:19:22 GMT (10kb)

Title: Accurate determination of electric-dipole matrix elements in K and Rb

from Stark shift measurements

Authors: Bindiya Arora, M. S. Safronova, and Charles W. Clark

Categories: physics.atom-ph

Comments: 5 pages

\\

Stark shifts of potassium and rubidium D1 lines have been measured with high

precision by Miller et al [1]. In this work, we combine these measurements with

our all-order calculations to determine the values of the electric-dipole

matrix elements for the 4p_j-3d_j' transitions in K and for the 5p_j-4d_j'

transitions in Rb to high precision. The 4p_1/2-3d_3/2 and 5p_1/2-4d_3/2

transitions contribute on the order of 90% to the respective polarizabilities

of the np_1/2 states in K and Rb, and the remaining 10% can be accurately

calculated using the relativistic all-order method. Therefore, the combination

of the experimental data and theoretical calculations allows us to determine

the np-(n-1)d matrix elements and their uncertainties. We compare these values

with our all-order calculations of the np-(n-1)d matrix elements in K and Rb

for a benchmark test of the accuracy of the all-order method for transitions

involving nd states. Such matrix elements are of special interest for many

applications, such as determination of magic wavelengths in alkali-metal atoms

for state-insensitive cooling and trapping and determination of blackbody

radiation shifts in optical frequency standards with ions.

\\ ( http://arxiv.org/abs/0709.0014 , 10kb)

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

\\

arXiv:0709.0130

Date: Sun, 2 Sep 2007 21:26:16 GMT (52kb)

Title: Magic wavelengths for the np-ns transitions in alkali-metal atoms

Authors: Bindiya Arora, M. S. Safronova, and Charles W. Clark

Categories: physics.atom-ph

Comments: 12 pages, 8 figures

\\

Extensive calculations of the electric-dipole matrix elements in alkali-metal

atoms are conducted using the relativistic all-order method. This approach is a

linearized version of the coupled-cluster method, which sums infinite sets of

many-body perturbation theory terms. All allowed transitions between the lowest

ns, np_1/2, np_3/2 states and a large number of excited states are considered

in these calculations and their accuracy is evaluated. The resulting

electric-dipole matrix elements are used for the high-precision calculation of

frequency-dependent polarizabilities of the excited states of alkali-metal

atoms. We find magic wavelengths in alkali-metal atoms for which the ns and

np_1/2 and np_3/2 atomic levels have the same ac Stark shifts, which

facilitates state-insensitive optical cooling and trapping.

\\ ( http://arxiv.org/abs/0709.0130 , 52kb)

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

\\

arXiv:0709.0359

Date: Tue, 4 Sep 2007 08:15:22 GMT (125kb)

Title: Adiabatic Fidelity for Atom-Molecule Conversion in a Nonlinear

Three-Level $\Lambda$-system

Authors: Shao-Ying Meng, Li-Bin Fu, Jie Liu

Categories: cond-mat.other

Comments: 4 pages, 5 figures

\\

We investigate the dynamics of the population transfer for atom-molecule

three-level $\Lambda$-system on stimulated Raman adiabatic passage(STIRAP). We

find that the adiabatic fidelity for the coherent population trapping(CPT)

state or dark state, as the function of the adiabatic parameter, approaches to

unit in a power law. The power exponent however is much less than the

prediction of linear adiabatic theorem. We further discuss how to achieve

higher adiabatic fidelity for the dark state through optimizing the external

parameters of STIRAP. Our discussions are helpful to gain higher atom-molecule

conversion yield in practical experiments.

\\ ( http://arxiv.org/abs/0709.0359 , 125kb)

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

\\

arXiv:0709.0362

Date: Tue, 4 Sep 2007 08:29:58 GMT (230kb)

Title: Non-perturbative renormalization-group approach to zero-temperature Bose

systems

Authors: N. Dupuis and K. Sengupta

Categories: cond-mat.other

Comments: 6 pages, 8 figures

\\

We use a non-perturbative renormalization-group technique to study

interacting bosons at zero temperature. Our approach reveals the instability of

the Bogoliubov fixed point when $d\leq 3$ and yields the exact infrared

behavior in all dimensions $d>1$ within a rather simple theoretical framework.

It also enables to compute the low-energy properties in terms of the parameters

of a microscopic model. In one-dimension and for not too strong interactions,

it yields a good picture of the Luttinger-liquid behavior of the superfluid

phase.

\\ ( http://arxiv.org/abs/0709.0362 , 230kb)

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

\\

arXiv:0709.0368

Date: Tue, 4 Sep 2007 09:05:18 GMT (20kb)

Title: Vortex spectrum in superfluid turbulence: interpretation of a recent

experiment

Authors: Philippe-Emmanuel P.-E. Roche (NEEL), Carlo F. Barenghi

Categories: cond-mat.other

Comments: Submitted for publication

http://crtbt.grenoble.cnrs.fr/helio/GROUP/infa.html

http://www.mas.ncl.ac.uk/~ncfb/

Proxy: ccsd hal-00169495

\\

We discuss a recent experiment in which the spectrum of the vortex line

density fluctuations has been measured in superfluid turbulence. The observed

frequency dependence of the spectrum, $f^{-5/3}$, disagrees with classical

vorticity spectra if, following the literature, the vortex line density is

interpreted as a measure of the vorticity or enstrophy. We argue that the

disagrement is solved if the vortex line density field is decomposed into a

polarised field (which carries most of the energy) and an isotropic field

(which is responsible for the spectrum).

\\ ( http://arxiv.org/abs/0709.0368 , 20kb)

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

\\

arXiv:0709.0388

Date: Tue, 4 Sep 2007 10:34:34 GMT (626kb)

Title: Effects of a Fluctuating Interface between a Superfluid and a Polarized

Fermi Gas

Authors: Hui Zhai and Dung-Hai Lee

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

Comments: 4 pages, 3 figures

\\

Motivated by recent experiments in trapped Fermi gas with spin population

imbalance, we discuss the effects of the quantum and thermal fluctuations of

the interface between a fully paired superfluid core and a fully polarized

Fermi gas. We demonstrate that even if there is no true partially polarized

thermodynamic phase in bulk, the interface fluctuation can give rise to a

partially polarized transition regime in trap. Our theory yields a definite

prediction for the functional forms of the spatial profile of spin polarization

and pairing gap, and we show that the spin-resolved density profiles measured

by both the MIT and Rice groups obey this function form. We also show that

sufficient large fluctuation will lead to a visibly unequal density even at the

center of the cloud. We hope this picture can shed lights on the controversial

discrepancies in recent experiments.

\\ ( http://arxiv.org/abs/0709.0388 , 626kb)

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

\\

arXiv:0709.0405

Date: Tue, 4 Sep 2007 12:12:08 GMT (17kb)

Title: Metastability of persistent currents in trapped gases of atoms

Authors: K. Karkkainen (1), J. Christensson (1), G. Reinisch (2), G. M.

Kavoulakis (1), S. M. Reimann (1) ((1) LTH, Lund, (2) Nice)

Categories: cond-mat.other

Comments: 7 pages, RevTex, 5 figures

\\

We examine the conditions that give rise to metastable, persistent currents

in a trapped Bose-Einstein condensate. A necessary condition for the stability

of persistent currents is that the trapping potential is not a monotonically

increasing function of the distance from the trap center. Persistent currents

also require that the interatomic interactions are sufficiently strong and

repulsive. Finally, any off-center vortex state is shown to be unstable, while

a driven gas shows hysteresis.

\\ ( http://arxiv.org/abs/0709.0405 , 17kb)

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

\\

arXiv:0709.0499

Date: Tue, 4 Sep 2007 18:48:24 GMT (116kb)

Title: Scattering Models for Ultracold Atoms

Authors: Eric Braaten, Masaoki Kusunoki and Dongqing Zhang

Categories: cond-mat.other

Comments: 60 pages, 6 figures

\\

We present a review of scattering models that can be used to describe the

low-energy behavior of identical bosonic atoms. In the simplest models, the

only degrees of freedom are atoms in the same spin state. More elaborate models

have other degrees of freedom, such as atoms in other spin states or diatomic

molecules. The parameters of the scattering models are specified by giving the

S-wave phase shifts for scattering of atoms in the spin state of primary

interest. The models are formulated as local quantum field theories and the

renormalization of their coupling constants is determined. Some of the

parameters can be constrained by renormalizability or by the absence of

negative-norm states. The Green's functions that describe the evolution of

two-atom states are determined analytically. They are used to determine the

T-matrix elements for atom-atom scattering and the binding energies of diatomic

molecules. The scattering models all exhibit universal behavior as the

scattering length in a specific spin state becomes large.

\\ ( http://arxiv.org/abs/0709.0499 , 116kb)

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

\\

arXiv:0709.0343

Date: Tue, 4 Sep 2007 07:28:34 GMT (670kb)

Title: Exactly-solvable coupled-channel potential models of atom-atom magnetic

Feshbach resonances from supersymmetric quantum mechanics

Authors: Andrey M. Pupasov, Boris F. Samsonov, Jean-Marc Sparenberg

Categories: quant-ph

Comments: 19 pages, 15 figures

\\

Starting from a system of $N$ radial Schr\"odinger equations with a vanishing

potential and finite threshold differences between the channels, a coupled $N

\times N$ exactly-solvable potential model is obtained with the help of a

single non-conservative supersymmetric transformation. The obtained potential

matrix, which subsumes a result obtained in the literature, has a compact

analytical form, as well as its Jost matrix. It depends on $N (N+1)/2$

unconstrained parameters and on one upper-bounded parameter, the factorization

energy. A detailed study of the model is done for the $2\times 2$ case: a

geometrical analysis of the zeros of the Jost-matrix determinant shows that the

model has 0, 1 or 2 bound states, and 0 or 1 resonance; the potential

parameters are explicitly expressed in terms of its bound-state energies, of

its resonance energy and width, or of the open-channel scattering length, which

solves schematic inverse problems. As a first physical application,

exactly-solvable $2\times 2$ atom-atom interaction potentials are constructed,

for cases where a magnetic Feshbach resonance interplays with a bound or

virtual state close to threshold, which results in a large background

scattering length.

\\ ( http://arxiv.org/abs/0709.0343 , 670kb)

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

\\

arXiv:0709.0352

Date: Tue, 4 Sep 2007 07:55:18 GMT (78kb)

Title: Macroscopic Entanglement of a Bose Einstein Condensate on a

Superconducting Atom Chip

Authors: Mandip Singh

Categories: quant-ph

Comments: 4 Pages, Two figures

\\

We propose and analyse a practically implementable scheme to generate

macroscopic entanglement of a Bose-Einstein condensate in a micro-magnetic trap

magnetically coupled to a superconducting loop. We treat the superconducting

loop in a quantum superposition of two different flux states coupled with the

magnetic trap to generate macroscopic entanglement. Our scheme also provides a

platform to realise interferometry of entangled atoms through the Bose-Einstein

condensate and to explore physics at the quantum-classical interface.

\\ ( http://arxiv.org/abs/0709.0352 , 78kb)

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

\\

arXiv:0709.0527

Date: Tue, 4 Sep 2007 20:13:07 GMT (564kb,D)

Title: Quantum Non-Demolition Detection of Strongly Correlated Systems

Authors: Kai Eckert, Oriol Romero-Isart, Mirta Rodriguez, Maciej Lewenstein,

Eugene S. Polzik and Anna Sanpera

Categories: cond-mat.other

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

submitted version

\\

Preparation, manipulation, and detection of strongly correlated states of

quantum many body systems are among the most important goals and challenges of

modern physics. Ultracold atoms offer an unprecedented playground for

realization of these goals. Here we show how strongly correlated states of

ultracold atoms can be detected in a quantum non-demolition scheme, that is, in

the fundamentally least destructive way permitted by quantum mechanics. In our

method, spatially resolved components of atomic spins couple to quantum

polarization degrees of freedom of light. In this way quantum correlations of

matter are faithfully mapped on those of light; the latter can then be

efficiently measured using homodyne detection. We illustrate the power of such

spatially resolved quantum noise limited polarization measurement by applying

it to detect various standard and "exotic" types of antiferromagnetic order in

lattice systems and by indicating the feasibility of detection of superfluid

order in Fermi liquids.

\\ ( http://arxiv.org/abs/0709.0527 , 564kb)

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

\\

arXiv:0709.0605

Date: Wed, 5 Sep 2007 13:58:59 GMT (518kb)

Title: AC-induced superfluidity

Authors: Andre Eckardt and Martin Holthaus

Categories: cond-mat.other

Comments: 6 pages, 4 figures

\\

We argue that a system of ultracold bosonic atoms in a tilted optical lattice

can become superfluid in response to resonant AC forcing. Among others, this

allows one to prepare a Bose-Einstein condensate in a state associated with a

negative effective mass. Our reasoning is backed by both exact numerical

simulations for systems consisting of few particles, and by a theoretical

approach based on Floquet-Fock states.

\\ ( http://arxiv.org/abs/0709.0605 , 518kb)

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

\\

arXiv:0709.0656

Date: Wed, 5 Sep 2007 14:00:02 GMT (900kb)

Title: Hidden Fermi Liquid: The Secret of High Tc Cuprates

Authors: Philip W Anderson

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

\\

I present a formalism for dealing directly with the effects of the Gutzwiller

projection, which is implicit in the t-J model widely believed to underly the

phenomenology of the high-Tc cuprates. I suggest that a true BCS condensation

from a Fermi liquid state takes place, but in the unphysical space prior to

projection. The theory which results upon projection does not follow

conventional rules of diagram theory and in fact in the normal state is a Z=0

non-Fermi liquid. Anomalous properties of this strange metal normal state are

predicted and compared to experiments.

\\ ( http://arxiv.org/abs/0709.0656 , 900kb)

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\\

arXiv:0709.0698

Date: Wed, 5 Sep 2007 16:39:22 GMT (192kb)

Title: Probing two-fluid hydrodynamics in a trapped Fermi superfluid at

unitarity

Authors: Edward Taylor, Hui Hu, Xia-Ji Liu, Allan Griffin

Categories: cond-mat.other

Comments: 5 pages, 3 figures

\\

We develop a variational approach to calculate the density response function

at finite temperatures of the lowest-lying two-fluid modes in a trapped

two-component Fermi superfluid close to a Feshbach resonance. The out-of-phase

oscillations, which are the analogue in trapped gases of second sound in

uniform superfluids, have so far not been observed in cold-atom experiments. We

show that these modes are observable via two-photon Bragg scattering, whose

spectrum is proportional to the imaginary part of density response function. We

predict pronounced peaks for the out-of-phase modes in the Bragg scattering

spectrum at unitarity at finite temperatures. This provides strong evidence for

superfluidity at unitarity and a promising way to probe the unitarity equation

of state.

\\ ( http://arxiv.org/abs/0709.0698 , 192kb)

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\\

arXiv:0709.0613

Date: Wed, 5 Sep 2007 10:29:24 GMT (14kb)

Title: Complementarity and uncertainty relations for matter wave interferometry

Authors: K.-P. Marzlin, B. C. Sanders, and P. L. Knight

Categories: quant-ph

Comments: four pages, one figure

\\

We provide a rigorous quantitative connection between the complementarity

relations of path information vs fringe visibility for a particle in an

interferometer and uncertainty relations between position and modular momentum.

This theory is applied to atom interferometry wherein spontaneously emitted

photons can provide path information, and we show that the metamaterial

`perfect lens' enables atom interferometry to reach an extremum of this

complementarity trade-off.

\\ ( http://arxiv.org/abs/0709.0613 , 14kb)

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

\\

arXiv:0709.0716

Date: Wed, 5 Sep 2007 17:49:31 GMT (47kb)

Title: Maximum Entanglement in Squeezed Boson and Fermion States

Authors: F.C. Khanna, J.M.C. Malbouisson, A.E. Santana, E.S. Santos

Categories: quant-ph

Comments: 4 pages

Journal-ref: Phys. Rev A {\bf 76}, 022109 (2007)

DOI: 10.1103/PhysRevA.76.022109

\\

A class of squeezed boson and fermion states is studied with particular

emphasis on the nature of entanglement. We first investigate the case of

bosons, considering two-mode squeezed states. Then we construct the fermion

version to show that such states are maximum entangled, for both bosons and

fermions. To achieve these results, we demonstrate some relations involving

squeezed boson states. The generalization to the case of fermions is made by

using Grassmann variables.

\\ ( http://arxiv.org/abs/0709.0716 , 47kb)

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

\\

arXiv:0709.0817

Date: Thu, 6 Sep 2007 10:08:42 GMT (21kb)

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

radio-frequency spectra of ultracold Fermi atoms

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

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

Comments: 4 pages, 3 figures

\\

The radio-frequency spectra of ultracold Fermi atoms are calculated by

including final-state interactions affecting the excited level of the

transition, and compared quantitatively with the experimental data. This

inclusion reveals a competition between pairing-gap effects which tend to push

the oscillator strength toward high frequencies away from threshold, and

final-state effects which tend instead to pull the oscillator strength toward

threshold. As a result of this competition, the position of the peak of the

spectra cannot be simply related to the value of the pairing gap, whose

extraction thus requires support from theoretical calculations.

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

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

\\

arXiv:0709.0895

Date: Thu, 6 Sep 2007 15:49:48 GMT (207kb,D)

Title: Vortex nucleation in Bose-Einstein Condensates subject to light induced

effective magnetic fields

Authors: D. R. Murray, P \"Ohberg, Dami\'a Gomila and Stephen M. Barnett

Categories: cond-mat.other

Comments: 7 pages, 7 figures

\\

We numerically simulate vortex nucleation in a Bose-Einstein Condensate (BEC)

subject to an effective magnetic field. The effective magnetic field is

generated from the interplay between light with a non-trivial phase structure

and the BEC, and can be shaped and controlled by appropriate modifications to

the phase and intensity of the light. We demonstrate that the nucleation of

vortices is seeded by instabilities in surface excitations which are coupled to

by an asymmetric trapping potential (similar to the case of condensates subject

to mechanical rotation) and show that this picture also holds when the applied

effective magnetic field is not homogeneous. The eventual configuration of

vortices in the cloud depends on the geometry of the applied field.

\\ ( http://arxiv.org/abs/0709.0895 , 207kb)

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

\\

arXiv:0708.4304 (*cross-listing*)

Date: Fri, 31 Aug 2007 09:31:00 GMT (463kb,D)

Title: Control of atomic currents using a quantum stirring device

Authors: Moritz Hiller, Tsampikos Kottos, Doron Cohen

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

Comments: 5 pages, 4 figures

\\

We propose a BEC stirring device which can be regarded as the incorporation

of a quantum pump into a closed circuit: it produces a DC circulating current

in response to a cyclic adiabatic change of two control parameters of an

optical trap. We demonstrate the feasibility of this concept and point out that

such device can be utilized in order to probe the interatomic interactions.

\\ ( http://arxiv.org/abs/0708.4304 , 463kb)

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\\

arXiv:0709.0754

Date: Thu, 6 Sep 2007 16:51:51 GMT (951kb)

Title: Coherent Control of Trapped Bosons

Authors: Analabha Roy, Linda E. Reichl

Categories: physics.atom-ph

Comments: 17 figures

\\

We investigate the quantum behavior of a mesoscopic two-boson system produced

by number-squeezing ultracold gases of alkali metal atoms. The quantum Poincare

maps of the wavefunctions are affected by chaos in those regions of the phase

space where the classical dynamics produces features that are comparable to

hbar. We also investigate the possibility for quantum control in the dynamics

of excitations in these systems. Controlled excitations are mediated by pulsed

signals that cause Stimulated Raman Adiabatic passage (STIRAP) from the ground

state to a state of higher energy. The dynamics of this transition is affected

by chaos caused by the pulses in certain regions of the phase space. A

transition to chaos can thus provide a method of controlling STIRAP.

\\ ( http://arxiv.org/abs/0709.0754 , 951kb)

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

\\

arXiv:0709.0827

Date: Thu, 6 Sep 2007 10:48:42 GMT (162kb)

Title: Sympathetic cooling in a mixture of diamagnetic and paramagnetic atoms

Authors: S. Tassy, N. Nemitz, F. Baumer, C. H\"ohl, A. Bat\"ar, A. G\"orlitz

Categories: physics.atom-ph

Comments: 4 pages, 4 figures

\\

We have experimentally realized a hybrid trap for ultracold paramagnetic

rubidium and diamagnetic ytterbium atoms by combining a bichromatic optical

dipole trap for ytterbium with a Ioffe-Pritchard-type magnetic trap for

rubidium. In this hybrid trap, sympathetic cooling of five different ytterbium

isotopes through elastic collisions with rubidium was achieved. A strong

dependence of the interspecies collisional cross section on the mass of the

ytterbium isotope was observed.

\\ ( http://arxiv.org/abs/0709.0827 , 162kb)

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

More soon,

Matt.

-- ========================================================================= Dr M. J. Davis, Senior Lecturer in Physics School of Physical Sciences, email: mdavis_at_physics.uq.edu.au University of Queensland, ph : +61 7 334 69824 Brisbane, QLD 4072, fax : +61 7 336 51242 Australia. http://www.physics.uq.edu.au/people/mdavis/ ========================================================================= Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland =========================================================================Received on Sat Oct 06 2007 - 22:07:09 EST

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