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

Date: Fri, 10 Jul 2009 14:43:33 +1000

Date: Fri, 10 Jul 2009 14:43:33 +1000

Dear subscribers,

This week we thank Mike Garrett. There are a massive 33 new preprints and 17

replacements:

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arXiv:0906.2202

Date: Fri, 12 Jun 2009 17:10:29 GMT (97kb)

Title: Pair Density Wave Instability of Cold Fermionic Atoms in an Optical

Lattice

Authors: Predrag Nikolic, A.A. Burkov, Arun Paramekanti

Categories: cond-mat.supr-con cond-mat.quant-gas

Comments: 4 pages, 3 figures

\\

We show that the band insulating state of cold fermionic atoms in a

three-dimensional cubic optical lattice is unstable to forming a pair-density

wave (PDW) state in the presence of strong attractive interactions induced by

proximity to a Feshbach resonance. The PDW state in this model is a special

type of supersolid, which arises from the condensation of predominantly

interband Cooper pairs at a nonzero, generically incommensurate, wavevector,

and is expected to be accompanied by an induced density modulation. We also

discuss the mean field phase diagram of a two-band tight binding model, which

exhibits a PDW state, and discuss the relation of the PDW instability in this

model to the Halperin-Rice exciton condensation instability in indirect bandgap

semiconductors.

\\ ( http://arxiv.org/abs/0906.2202 , 97kb)

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arXiv:0906.2264

Date: Fri, 12 Jun 2009 06:39:23 GMT (816kb)

Title: Entropy exchange in a mixture of ultracold atoms

Authors: J. Catani, G. Barontini, G. Lamporesi, F. Rabatti, G. Thalhammer, F.

Minardi, S. Stringari, M. Inguscio

Categories: cond-mat.quant-gas

Comments: 5 pages, 4 figures

\\

We investigate experimentally the entropy transfer between two

distinguishable atomic quantum gases at ultralow temperatures. Exploiting a

species-selective trapping potential, we are able to control the entropy of one

target gas in presence of a second auxiliary gas. With this method, we drive

the target gas into the degenerate regime in conditions of controlled

temperature by transferring entropy to the auxiliary gas. We envision that our

method could be useful both to achieve the low entropies required to realize

new quantum phases and to measure the temperature of atoms in deep optical

lattices.

\\ ( http://arxiv.org/abs/0906.2264 , 816kb)

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arXiv:0906.2314

Date: Fri, 12 Jun 2009 12:38:03 GMT (234kb)

Title: Decay of superfluid currents in the interacting one-dimensional Bose gas

Authors: Alexander Yu. Cherny, Jean-Sebastien Caux, and Joachim Brand

Categories: cond-mat.quant-gas cond-mat.stat-mech

Comments: 4 pages, 4 figures

\\

We examine the superfluid properties of a 1D Bose gas in a ring trap based on

the model of Lieb and Liniger. While the 1D Bose gas has nonclassical

rotational inertia and exhibits quantization of velocities, the metastability

of currents depends sensitively on the strength of interactions in the gas: the

stronger the interactions, the faster the current decays. It is shown that the

Landau critical velocity is zero in the thermodynamic limit due to the first

supercurrent state, which has zero energy and finite probability of excitation.

We calculate the energy dissipation rate of ring currents in the presence of

weak defects, which should be observable on experimental time scales.

\\ ( http://arxiv.org/abs/0906.2314 , 234kb)

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arXiv:0906.2033

Date: Thu, 11 Jun 2009 18:27:02 GMT (1341kb)

Title: Semiclassical Theory for Universality in Quantum Chaos with Symmetry

Crossover

Authors: Keiji Saito, Taro Nagao, Sebastian Muller, and Petr Braun

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

Comments: 24 pages, 4 figures

\\

We address the quantum-classical correspondence for chaotic systems with a

crossover between symmetry classes. We consider the energy level statistics of

a classically chaotic system in a weak magnetic field. The generating function

of spectral correlations is calculated by using the semiclassical

periodic-orbit theory. An explicit calculation up to the second order,

including the non-oscillatory and oscillatory terms, agrees with the prediction

of random matrix theory. Formal expressions of the higher order terms are also

presented. The nonlinear sigma (NLS) model of random matrix theory, in the

variant of the Bosonic replica trick, is also analyzed for the crossover

between the Gaussian orthogonal ensemble and Gaussian unitary ensemble. The

diagrammatic expansion of the NLS model is interpreted in terms of the periodic

orbit theory.

\\ ( http://arxiv.org/abs/0906.2033 , 1341kb)

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arXiv:0906.2257

Date: Fri, 12 Jun 2009 05:25:13 GMT (858kb)

Title: Generating a Fractal Butterfly Floquet Spectrum in a Class of Driven

SU(2) Systems

Authors: Jiao Wang and Jiangbin Gong

Categories: quant-ph

Comments: 11 pages, 9 figures, relatively large size, a full-length report of

the findings in arXiv 0906.2259

\\

A scheme for generating a fractal butterfly Floquet spectrum, first proposed

by Wang and Gong [Phys. Rev. A {\bf 77}, 031405(R) (2008)], is extended to

driven SU(2) systems such as a driven two-mode Bose-Einstein condensate. A new

class of driven systems without a link with the Harper model context is shown

to have an intriguing butterfly Floquet spectrum. The found butterfly spectrum

shows remarkable deviations from the known Hosftadter's butterfly. In addition,

the level crossings between Floquet states of the same parity and between

Floquet states of different parities are studied and highlighted. The results

are relevant to studies of fractal statistics, quantum chaos, coherent

destruction of tunneling, as well as the validity of mean-field descriptions of

Bose-Einstein condensates.

\\ ( http://arxiv.org/abs/0906.2257 , 858kb)

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arXiv:0906.2259

Date: Fri, 12 Jun 2009 05:23:25 GMT (410kb)

Title: Butterfly Floquet Spectrum in Driven SU(2) Systems

Authors: Jiao Wang and Jiangbin Gong

Categories: quant-ph

Comments: 4 pages, 4 figures, to appear in Phys. Rev. Lett., for a full-length

report see arXiv 0906.2257

\\

The Floquet spectrum of a class of driven SU(2) systems is shown to display a

butterfly pattern with multi-fractal properties. The level crossing between

Floquet states of the same parity or different parities is studied. The results

are relevant to studies of fractal statistics, quantum chaos, coherent

destruction of tunneling, and the validity of mean-field descriptions of

Bose-Einstein condensates.

\\ ( http://arxiv.org/abs/0906.2259 , 410kb)

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arXiv:0906.2272

Date: Fri, 12 Jun 2009 08:00:19 GMT (2069kb)

Title: Enhancement of thermal Casimir-Polder potentials of ground-state polar

molecules in a planar cavity

Authors: Simen A. Ellingsen, Stefan Yoshi Buhmann, Stefan Scheel

Categories: quant-ph

Comments: 12 pages, 10 figures

\\

We analyze the thermal Casimir-Polder potential experienced by a ground-state

molecule in a planar cavity and investigate the prospects for using such a

set-up for molecular guiding. The resonant atom-field interaction associated

with this non-equilibrium situation manifests itself in oscillating,

standing-wave components of the potential. While the respective potential wells

are normally too shallow to be useful, they may be amplified by a highly

reflecting cavity whose width equals a half-integer multiple of a particular

molecular transition frequency. We find that with an ideal choice of molecule

and the use of ultra-high reflectivity Bragg mirror cavity, it may be possible

to boost the potential by up to two orders of magnitude. We analytically derive

the scaling of the potential depth as a function of reflectivity and analyze

how it varies with temperature and molecular properties. It is also shown how

the potential depth decreases for standing waves with a larger number of nodes.

Finally, we investigate the lifetime of the molecular ground state in a thermal

environment and find that it is not greatly influenced by the cavity and

remains in the order of several seconds.

\\ ( http://arxiv.org/abs/0906.2272 , 2069kb)

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arXiv:0906.2458

Date: Sat, 13 Jun 2009 08:59:13 GMT (583kb)

Title: Generalized Entropy from Mixing: Thermodynamics, Mutual Information and

Symmetry Breaking

Authors: Fariel Shafee

Categories: cond-mat.stat-mech

Comments: This review paper was written in Jan 2009 after the author received

an invitation for a review paper based on three papers that are part of her

Princeton Uni PhD thesis. These are her personal papers and the thesis was

approved under the supervision of self by Princeton University (based on her

personal papers done while she was a degree candidate)

\\

We review a new form of entropy suggested by us, with origin in mixing of

states of systems due to interactions and deformations of phase cells. It is

demonstrated that this nonextensive form also leads to asymmetric maximal

entropy configurations unlike Shannon entropy. We discuss how, beginning with

quantum entanglement of microsystems with one another and with the environment,

one can obtain classical stochasticity for our form of entropy.

\\ ( http://arxiv.org/abs/0906.2458 , 583kb)

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arXiv:0906.2522

Date: Sun, 14 Jun 2009 08:54:06 GMT (30kb)

Title: Extension of the integrable, (1+1) Gross-Pitaevskii equation to chaotic

behaviour and arbitrary dimensions

Authors: Bernhard Mieck

Categories: cond-mat.stat-mech nlin.SI

\\

The integrable, (1+1) Gross-Pitaevskii (GP-) equation with hermitian property

is extended to chaotic behaviour as part of general complex fields within the

sl(2,C) algebra for Lax pairs. Furthermore, we prove the involution property of

conserved quantities in the case of GP-type equations with an arbitrary

external potential. We generalize the approach of Lax pair matrices to

arbitrary spacetime dimensions and conclude for the type of nonlinear equations

from the structure constants of the underlying algebra. One can also calculate

conserved quantities from loops within the (N-1) dimensional base space and the

mapping to the manifold of the general SL(n,C) group or a sub-group, provided

that the resulting fibre space is of nontrivial homotopic kind.

\\ ( http://arxiv.org/abs/0906.2522 , 30kb)

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arXiv:0906.2531

Date: Sun, 14 Jun 2009 12:08:42 GMT (39kb)

Title: Coherent state path integral and nonlinear sigma model for a condensate

composed of fermions with precise, discrete steps in the time development

Authors: Bernhard Mieck

Categories: cond-mat.stat-mech

\\

A coherent state path integral is considered for fermions with precise,

discrete time separation. We derive in detail a nonlinear sigma model of a pair

condensate concerning the precise, discrete time step order which is usually

abbreviated by the appealing (but in fact non-existent) hermitian form of the

fields. This problem is ubiquitous in quantum many-body physics and already

occurs in the original Dyson equation. However, one has only to include a few

amendments concerning the precise, discrete time step development of coherent

state path integrals, compared to previous, abridged approaches, so that one

can accomplish the exact treatment of a spontaneous symmetry breaking with a

coset decomposition for pair condensates and density parts.

\\ ( http://arxiv.org/abs/0906.2531 , 39kb)

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arXiv:0906.2532

Date: Sun, 14 Jun 2009 12:39:51 GMT (32kb)

Title: Field theory with coherent states for many-body problems with specified

particle- and symmetry- quantum numbers (Non-relativistic electrons in a

central potential and an external magnetic field)

Authors: Bernhard Mieck

Categories: cond-mat.stat-mech

\\

Coherent state path integrals are applied to a many-body problem for

non-relativistic electrons in a central potential and an external magnetic

field; however, in comparison to previous coherent state path integrals, we

definitely fix the symmetry quantum numbers to specific values with second

quantized field operators which are restricted by delta functions of a Dirac

identity in a trace representation of anti-commuting coherent states. We

perform an anomalous doubling for the delta functions of the two-particle parts

so that a Hubbard-Stratonovich transformation can be taken for corresponding

self-energies with a coset decomposition. The given field theory can be

extended to an ensemble average over the external magnetic field so that mean

eigenvalue densities and eigenvalue correlations can be obtained.

\\ ( http://arxiv.org/abs/0906.2532 , 32kb)

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arXiv:0906.2551

Date: Sun, 14 Jun 2009 15:56:43 GMT (47kb)

Title: Induced supersolidity in a normal and hardcore boson mixture

Authors: Tapan Mishra, Ramesh V. Pai, B. P. Das

Categories: cond-mat.quant-gas

\\

It is well known that the supersolid form of matter can arise in a single

species of cold bosonic atoms in an optical lattice due to long range

interactions. We present a scenario where a supersolid is induced in one of the

components of a mixture of two species bosonic atoms where there is no long

range interactions. We study a system of normal and hardcore boson mixture with

only the former possessing long range interactions. We consider three cases:

the first where the total density is commensurate and the other two where they

are incommensurate . By suitable choices of the densities and the interaction

strengths of the atoms, we predict that the charge density wave and the

supersolid orders can be induced in the hardcore species as a result of the

competing interatomic interactions.

\\ ( http://arxiv.org/abs/0906.2551 , 47kb)

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arXiv:0906.2567

Date: Sun, 14 Jun 2009 18:33:09 GMT (190kb,D)

Title: Adiabatic preparation of many-body states in optical lattices

Authors: Anders S. Sorensen, Ehud Altman, Michael Gullans, J. V. Porto, Mikhail

D. Lukin, and Eugene Demler

Categories: cond-mat.quant-gas

Comments: 4+epsilon pages

\\

We analyze a technique for the preparation of low entropy many body states of

atoms in optical lattices based on adiabatic passage. In particular, we show

that this method allows preparation of strongly correlated states as stable

highest energy states of Hamiltonians that have trivial ground states. As an

example, we analyze the generation of antiferromagnetically ordered states by

adiabatic change of a staggered field acting on the spins of bosonic atoms with

ferromagnetic interactions.

\\ ( http://arxiv.org/abs/0906.2567 , 190kb)

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arXiv:0906.2580

Date: Mon, 15 Jun 2009 00:16:22 GMT (63kb)

Title: Exotic superfluidity in cold atoms

Authors: Elena Gubankova

Categories: cond-mat.quant-gas

Comments: 12 pages, 6 figures, proceedings of the conference "Shifmania,

Crossing the Boundaries: Gauge Dynamics at Strong Coupling", May 14-17, 2009

\\

We derived the low energy effective action for the collective modes in

asymmetric fermionic systems with attractive interaction. We obtained the phase

diagram in terms of the chemical potentials. It features a stable gapless

superfluidity with one Fermi surface on the BEC side of the resonance. Also we

predict a sharp increase in outer core of a vortex, i.e. vortex size, upon

entering into the gapless phase. This may serve as a signature of a gapless

phase.

\\ ( http://arxiv.org/abs/0906.2580 , 63kb)

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arXiv:0906.2610

Date: Mon, 15 Jun 2009 05:12:43 GMT (435kb,D)

Title: Transition region properties of a trapped quasi-two-dimensional

degenerate Bose gas

Authors: R. N. Bisset and P. B. Blakie

Categories: cond-mat.quant-gas

Comments: 5 pages 5 figures

\\

The c-field simulation technique is used to study a trapped quasi-two

dimensional Bose gas. We calculate the central curvature of the system density

and fluctuations of the condensate mode in the degenerate regime. These results

provide new understanding of the system behavior in the region of the

superfluid transition.

\\ ( http://arxiv.org/abs/0906.2610 , 435kb)

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arXiv:0906.2624

Date: Mon, 15 Jun 2009 07:43:50 GMT (405kb)

Title: Cavity Quantum Optomechanics of Ultracold Atoms in an Optical Lattice:

Normal-Mode Splitting

Authors: Aranya B Bhattacherjee

Categories: cond-mat.quant-gas

Comments: 6 figures

\\

We consider the dynamics of a movable mirror (cantilever) of a cavity coupled

through radiation pressure to the light scattered from ultracold atoms in an

optical lattice. Scattering from different atomic quantum states creates

different quantum states of the scattered light, which can be distinguished by

measurements of the displacement spectrum of the cantilever. We show that for

large pump intensities the steady state displacement of the cantilever shows

bistable behaviour. Due to atomic back-action, the displacement spectrum of the

cantilever is modified and depends on the position of the condensate in the

Brillouin zone. We further analyze the occurrence of splitting of the normal

mode into three modes due to mixing of the mechanical motion with the

fluctuations of the cavity field and the fluctuations of the condensate with

finite atomic two-body interaction. The present system offers a novel scheme to

coherently control ultracold atoms as well as cantilever dynamics.

\\ ( http://arxiv.org/abs/0906.2624 , 405kb)

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arXiv:0906.2640

Date: Mon, 15 Jun 2009 09:13:23 GMT (37kb)

Title: Trap-size scaling in confined particle systems at quantum transitions

Authors: Massimo Campostrini, Ettore Vicari

Categories: cond-mat.stat-mech

Comments: 4 pages, 2 figures

\\

We develop a trap-size scaling theory for trapped particle systems at quantum

transitions. As a theoretical laboratory, we consider a quantum XY chain in an

external transverse field acting as a trap for the spinless fermions of its

quadratic Hamiltonian representation. We discuss the trap-size scaling at the

Mott insulator to superfluid transition in the boson Hubbard model. We present

exact and accurate numerical results for the XY chain and for the hard-core

limit of the one-dimensional boson Hubbard model. Our results are relevant for

systems of cold atomic gases in optical lattices.

\\ ( http://arxiv.org/abs/0906.2640 , 37kb)

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arXiv:0906.2757

Date: Mon, 15 Jun 2009 18:37:46 GMT (14kb)

Title: S-ordered phase-space path integrals and time-s-ordering of Heisenberg

operators (reseach notes)

Authors: L.I.Plimak

Categories: cond-mat.stat-mech

\\

Formal structure of phase-space path integrals based on different types of

operator orderings is analysed.

\\ ( http://arxiv.org/abs/0906.2757 , 14kb)

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arXiv:0906.2572

Date: Sun, 14 Jun 2009 22:20:17 GMT (614kb,P)

Title: Squeezing of Atomic Quantum Projection Noise

Authors: Patrick J. Windpassinger, Daniel Oblak, Ulrich B. Hoff, Anne Louchet,

Jurgen Appel, Niels Kjaergaard, and Eugene S. Polzik

Categories: quant-ph

Comments: Submitted to Journal of Modern Optics

\\

We provide a framework for understanding recent experiments on squeezing of a

collective atomic pseudo-spin, induced by a homodyne measurement on

off-resonant probe light interrogating the atoms. The detection of light

decimates the atomic state distribution and we discuss the conditions under

which the resulting reduced quantum fluctuations are metrologically relevant.

In particular, we consider a dual probe scheme which benefits from a

cancelation of classical common mode noise sources such that quantum

fluctuations from light and atoms are the main contributions to the detected

signal.

\\ ( http://arxiv.org/abs/0906.2572 , 614kb)

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arXiv:0906.2904

Date: Tue, 16 Jun 2009 12:12:14 GMT (1387kb)

Title: Laser Cooling by Collisional Redistribution of Radiation

Authors: Ulrich Vogl and Martin Weitz

Categories: cond-mat.quant-gas

Comments: Nature (in press)

\\

The general idea that optical radiation may cool matter was put forward by

Pringsheim already in 1929. Doppler cooling of dilute atomic gases is an

extremely successful application of this concept, and more recently anti-Stokes

cooling in multilevel systems has been explored, culminating in the optical

refrigeration of solids. Collisional redistribution of radiation is a proposed

different cooling mechanism that involves atomic two-level systems, though

experimental investigations in gases with moderate density have so far not

reached the cooling regime.

Here we experimentally demonstrate laser cooling of an atomic gas based on

collisional redistribution of radiation, using rubidium atoms subject to 230

bar of argon buffer gas pressure. The frequent collisions in the ultradense gas

transiently shift a far red detuned laser beam into resonance, while

spontaneous decay occurs close to the unperturbed atomic resonance frequency.

During each excitation cycle, a kinetic energy of order of the thermal energy

k_B T is extracted from the dense atomic sample. In a proof of principle

experiment with a thermally non-isolated sample, we experimentally demonstrate

relative cooling by 66 K. The cooled gas has a density of more than 10 orders

of magnitude above the typical values in Doppler cooling experiments, and the

cooling power reaches 87 mW. Future prospects of the demonstrated effect

include studies of supercooling beyond the homogeneous nucleation temperature

and optical chillers.

\\ ( http://arxiv.org/abs/0906.2904 , 1387kb)

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arXiv:0906.2908

Date: Tue, 16 Jun 2009 12:19:47 GMT (48kb)

Title: Anomalous behavior of q-averages in nonextensive statistical mechanics

Authors: Sumiyoshi Abe (1,2,3) ((1) Mie University, Mie, Japan, (2) ISMANS, Le

Mans, France, (3) Inspire Institute Inc., Virginia, USA)

Categories: cond-mat.stat-mech

Comments: 14 pages, no figures. Accepted for publication in J. Stat. Mech.

\\

A generalized definition of average, termed the q-average, is widely employed

in the field of nonextensive statistical mechanics. Recently, it has however

been pointed out that such an average value may behave unphysical under

specific deformations of probability distributions. Here, the following three

issues are discussed and clarified. Firstly, the deformations considered are

physical and may experimentally be realized. Secondly, in view of

thermostatistics, the q-average is unstable in both finite and infinite

discrete systems. Thirdly, a naive generalization of the discussion to

continuous systems misses a point, and a norm better than the $L^1$-norm should

be employed for measuring the distance between two probability distributions.

Consequently, stability of the q-average is shown not to be established in all

the cases.

\\ ( http://arxiv.org/abs/0906.2908 , 48kb)

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arXiv:0905.0669

Date: Tue, 5 May 2009 18:49:18 GMT (372kb)

Date (revised v2): Thu, 14 May 2009 19:43:40 GMT (421kb)

Title: Unitary circuits for strongly correlated fermions

Authors: C. Pineda, T. Barthel, J. Eisert

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

Comments: 5 pages, 3 figures, numerical example added, small typographic errors

corrected

\\

We introduce a scheme for efficiently describing pure states of strongly

correlated fermions in higher dimensions using unitary circuits. A local way of

computing local expectation values is presented. We formulate a dynamical

reordering scheme, corresponding to time-adaptive Jordan-Wigner transformation

that avoids non-local string operators and only keeps suitably ordered the

causal cone. Primitives of such a reordering scheme are highlighted. Fermionic

unitary circuits can be contracted with the same complexity as in the spin

case. The scheme gives rise to a variational description of fermionic models

that does not suffer from a sign problem. We present a numerical example on a

9x9 fermionic lattice model to show the functioning of the approach.

\\ ( http://arxiv.org/abs/0905.0669 , 421kb)

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arXiv:0906.2842

Date: Tue, 16 Jun 2009 04:37:50 GMT (2045kb)

Title: Synchronization in non dissipative optical lattices

Authors: Daniel Hennequin (PhLAM), Philippe Verkerk (PhLAM)

Categories: physics.atom-ph

\\

The dynamics of cold atoms in conservative optical lattices obviously depends

on the geometry of the lattice. But very similar lattices may lead to deeply

different dynamics. For example, in a 2D optical lattice with a square mesh,

the sign of the detuning plays a crucial role: in the blue detuned case,

trajectories of an atom inside a well are chaotic for high enough energies. On

the contrary, in the red detuned case, chaos is completely inhibited inside the

wells. Here, we study in details the dynamical regimes of atoms inside a well

of a red detuned lattice, with the aim to understand the dynamical mechanisms

leading to the disappearance of chaos. We show that the motions in the two

directions of space are frequency locked in most of the phase space, for most

of the parameters of the lattice and atoms. This synchronization, not as strict

as that of a dissipative system, is nevertheless a mechanism powerful enough to

explain that chaos cannot appear in red detuned lattices.

\\ ( http://arxiv.org/abs/0906.2842 , 2045kb)

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arXiv:0906.2880

Date: Tue, 16 Jun 2009 09:32:29 GMT (1586kb)

Title: Thermal properties of AlN-based atom chips

Authors: Julien Armijo (LCFIO), Carlos Garrido Alzar (LCFIO), Isabelle

Bouchoule (LCFIO)

Categories: physics.atom-ph

\\

We have studied the thermal properties of atom chips consisting o high

thermal conductivity Aluminum Nitride (AlN) substrates on which gold microwires

are directly deposited. We have measured the heating of wires of several widths

and with different thermal couplings to the copper mount holding the chip. The

results are in good agreement with a theoretical model where the copper mount

is treated as a heat sink and the thermal interface resistance between the wire

and the substrate is vanishing. We give analytical formulas describing the

different transient heating regimes and the steady state. We identify criteria

to optimize the design of a chip as well as the maximal currents $I_c$ that can

be fed in the wires. For a 600$\mu$m thick-chip glued on a copper block with

Epotek H77, we find $I_c=16$A for a 3$\mu$m high, 200$\mu$m wide-wire.

\\ ( http://arxiv.org/abs/0906.2880 , 1586kb)

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arXiv:0906.2971

Date: Tue, 16 Jun 2009 16:54:03 GMT (1341kb,D)

Title: Laser-induced 3D alignment and orientation of quantum-state-selected

molecules

Authors: Iftach Nevo, Lotte Holmegaard, Jens H. Nielsen, Jonas L. Hansen,

Henrik Stapelfeldt, Frank Filsinger, Gerard Meijer, Jochen K\"upper

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

Comments: 8 pages, 7 figures

\\

A strong inhomogeneous static electric field is used to spatially disperse a

rotationally cold supersonic beam of 2,6-difluoroiodobenzene molecules

according to their rotational quantum state. The molecules in the lowest lying

rotational states are selected and used as targets for 3-dimensional alignment

and orientation. The alignment is induced in the adiabatic regime with an

elliptically polarized, intense laser pulse and the orientation is induced by

the combined action of the laser pulse and a weak static electric field. We

show that the degree of 3-dimensional alignment and orientation is strongly

enhanced when rotationally state-selected molecules, rather than molecules in

the original molecular beam, are used as targets.

\\ ( http://arxiv.org/abs/0906.2971 , 1341kb)

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arXiv:0906.3042

Date: Tue, 16 Jun 2009 23:05:35 GMT (449kb)

Title: Optical Kagome lattice for ultra-cold atoms with nearest neighbor

interactions

Authors: J. Ruostekoski

Categories: cond-mat.quant-gas cond-mat.str-el

\\

We propose a scheme to implement an optical Kagome lattice for ultra-cold

atoms with controllable s-wave interactions between nearest neighbor sites and

a gauge potential. The atoms occupy three different internal atomic levels with

electromagnetically-induced coupling between the levels. We show that by

appropriately shifting the triangular lattice potentials, experienced by atoms

in different levels, the Kagome lattice can be realized using only two standing

waves, generating a highly frustrated quantum system for the atoms.

\\ ( http://arxiv.org/abs/0906.3042 , 449kb)

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arXiv:0906.3081

Date: Wed, 17 Jun 2009 07:03:58 GMT (67kb)

Title: Berry Phase in Atom-Molecule Conversion Systems and Fractional Monopole

Authors: Li-Bin Fu and Jie Liu

Categories: cond-mat.quant-gas

Comments: 4 pages, 1 figure

\\

We investigate the geometric phase or Berry phase of adiabatic quantum

evolution in an atom-molecule conversion system, and find that the Berry phase

in such system consists of two parts: the usual Berry connection term and a

novel term from the nonlinearity brought forth by the atom-molecule conversion.

The geometric phase can be viewed as the flux of the magnetic field of a

monopole through the surface enclosed by a closed path in parameter space. The

charge of the monopole, however, is found to be one third of the elementary

charge of the usual quantized monopole.

\\ ( http://arxiv.org/abs/0906.3081 , 67kb)

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arXiv:0906.3142

Date: Wed, 17 Jun 2009 14:38:21 GMT (493kb)

Title: Numerical Studies of Counterflow Turbulence, Velocity Distribution of

Vortices

Authors: Hiroyuki Adachi and Makoto Tsubota

Categories: cond-mat.other

Comments: 6 pages, 12 figures, svjour3.sty

\\

We performed the numerical simulation of quantum turbulence produced by

thermal counterflow in superfluid $^{4}${\rm He} by using the vortex filament

model. The pioneering work was made by Schwarz, which has two defects. One is

neglecting non-local terms of the Biot-Savart integral (localized induction

approximation, LIA), and the other is the unphysical mixing procedure in order

to sustain the statistically steady state of turbulence. We succeeded in making

the statistically steady state without the LIA and the mixing. This state shows

the characteristic relation $L=\gamma^2 v_{ns}^2$ between the

line-length-density $L$ and the counterflow relative velocity $v_{ns}$ with the

quantitative agreement of the coefficient $\gamma$ with some typical

observations. We compare our numerical results to the observation of experiment

by Paoletti {\it et al}, where thermal couterflow was visualized by solid

hydrogen particles.

\\ ( http://arxiv.org/abs/0906.3142 , 493kb)

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arXiv:0906.3190

Date: Wed, 17 Jun 2009 14:24:10 GMT (113kb)

Title: Tunable ultranarrow linewidth of cavity induced by interacting dark

resonances

Authors: Y. D. Peng, L. L. Jin, Y. P. Niu, and S. Q. Gong

Categories: quant-ph

Comments: 4 pages, 5 figures

\\

A scheme for getting a tunable ultranarrow linewidth of a cavity due to an

embedded four-level atomic medium with double-dark resonances is proposed. It

is shown that the steep dispersion induced by double-dark resonances in the

transparency window leads to the ultranarrow transmission peak. Compared with

the case of a single-dark-resonance system, the linewidth can be narrowed even

by one order under proper conditions. Furthermore, the position of the

ultranarrow peak can be engineered by varying the intensity and detuning of the

control field.

\\ ( http://arxiv.org/abs/0906.3190 , 113kb)

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\\

arXiv:0906.3196

Date: Wed, 17 Jun 2009 14:32:53 GMT (11kb)

Title: Correlations in Free Fermionic States

Authors: M. Fannes and J. Wouters

Categories: quant-ph

Comments: 17 pages, no figures

\\

We study correlations in a bipartite, Fermionic, free state in terms of

perturbations induced by one party on the other. In particular, we show that

all so conditioned free states can be modelled by an auxiliary Fermionic system

and a suitable completely positive map.

\\ ( http://arxiv.org/abs/0906.3196 , 11kb)

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\\

arXiv:0906.3206

Date: Wed, 17 Jun 2009 15:33:03 GMT (294kb)

Title: Tackling the Gross-Pitaevskii energy functional with the Sobolev

gradient - Analytical and numerical results

Authors: P. Kazemi, M. Eckart

Categories: quant-ph

Comments: 30 pages, 9 figures, 3 tables

\\

In the first part of this contribution we prove the global existence and

uniqueness of a trajectory that globally converges to the minimizer of the

Gross-Pitaevskii energy functional for a large class of external potentials.

Using the method of Sobolev gradients we can provide an explicit construction

of this minimizing sequence.

In the second part we numerically apply these results to a specific

realization of the external potential and illustrate the main benefits of the

method of Sobolev gradients, which are high numerical stability and rapid

convergence towards the minimizer.

\\ ( http://arxiv.org/abs/0906.3206 , 294kb)

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arXiv:0906.3316

Date: Wed, 17 Jun 2009 21:45:56 GMT (913kb)

Title: Phase Separation and Dynamics of Two-component Bose-Einstein Condensates

Authors: R. Navarro, R. Carretero-Gonzalez, and P.G. Kevrekidis

Categories: cond-mat.quant-gas

Comments: 16 pages, 22 figures, submitted to Phys. Rev. A

\\

We study the interactions between two atomic species in a binary

Bose-Einstein condensate to revisit the conditions for miscibility, oscillatory

dynamics between the species, steady state solutions and their stability. By

employing a variational approach for a quasi one-dimensional, two-atomic

species, condensate we obtain equations of motion for the parameters of each

species: amplitude, width, position and phase. A further simplification leads

to a reduction of the dynamics into a simple classical Newtonian system where

components oscillate in an effective potential with a frequency that depends on

the harmonic trap strength and the interspecies coupling parameter. We develop

explicit conditions for miscibility that can be interpreted as a phase diagram

that depends on the harmonic trap's strength and the interspecies species

coupling parameter. We numerically illustrate the bifurcation scenario whereby

non-topological, phase-separated states of increasing complexity emerge out of

a symmetric state, as the interspecies coupling is increased. The

symmetry-breaking dynamical evolution of some of these states is numerically

monitored and the associated asymmetric states are also explored.

\\ ( http://arxiv.org/abs/0906.3316 , 913kb)

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arXiv:0906.3446

Date: Thu, 18 Jun 2009 14:09:23 GMT (76kb)

Title: Approximate expression for the dynamic structure factor in the

Lieb-Liniger model

Authors: Alexander Yu. Cherny and Joachim Brand

Categories: cond-mat.stat-mech cond-mat.quant-gas

Comments: 4 pages, 3 figures

Journal-ref: J. of Phys.: Conf. Ser. 129, 012051 (2008)

DOI: 10.1088/1742-6596/129/1/012051

\\

Recently, Imambekov and Glazman [Phys. Rev. Lett. 100, 206805 (2008)] showed

that the dynamic structure factor (DSF) of the 1D Bose gas demonstrates

power-law behaviour along the limiting dispersion curve of the collective modes

and calculated the corresponding exponents exactly. Combining these recent

results with a previously obtained strong-coupling expansion we present an

interpolation formula for the DSF of the 1D Bose gas. The obtained expression

is further consistent with exact low energy exponents from Luttinger liquid

theory and shows nice agreement with recent numerical results.

\\ ( http://arxiv.org/abs/0906.3446 , 76kb)

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The replacements:

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arXiv:0903.1326

replaced with revised version Fri, 12 Jun 2009 18:10:50 GMT (353kb)

Title: Possible vortex fluid to supersolid transition in solid $^4$He below

about 75 mK

Authors: Nobutaka Shimizu, Yoshinori Yasuta, and Minoru Kubota

Categories: cond-mat.other

Comments: 4 pages, 5 figures

\\ ( http://arxiv.org/abs/0903.1326 , 353kb)

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\\

arXiv:0905.3634

replaced with revised version Thu, 11 Jun 2009 22:11:33 GMT (374kb)

Title: Black-hole radiation in Bose-Einstein condensates

Authors: Jean Macher and Renaud Parentani

Categories: cond-mat.quant-gas gr-qc

Comments: revTeX 4, 55 pages single-column, 19 figures; v2: figure and refs

added, typos corrected, some convention changes

\\ ( http://arxiv.org/abs/0905.3634 , 374kb)

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arXiv:0802.0728

replaced with revised version Mon, 15 Jun 2009 11:28:35 GMT (166kb)

Title: Anomalous enhancement of quasiparticle current near a potential barrier

in a Bose-Einstein condensate

Authors: S. Tsuchiya, Y. Ohashi

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

Comments: 4 pages, 3 figures, published version

Journal-ref: Phys. Rev. A 78, 013628 (2008)

DOI: 10.1103/PhysRevA.78.013628

\\ ( http://arxiv.org/abs/0802.0728 , 166kb)

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arXiv:0902.2908

replaced with revised version Mon, 15 Jun 2009 11:43:45 GMT (77kb)

Title: Supercurrent induced by tunneling Bogoliubov excitations in a

Bose-Einstein condensate

Authors: Shunji Tsuchiya, Yoji Ohashi

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

Comments: 36 pages, 12 figures, revised version as accepted by Phys. Rev. A

\\ ( http://arxiv.org/abs/0902.2908 , 77kb)

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\\

arXiv:cond-mat/9204009

replaced with revised version Tue, 16 Jun 2009 01:00:12 GMT (328kb)

Title: Order Parameters, Broken Symmetry, and Topology

Authors: James P. Sethna

Categories: cond-mat

Comments: Lectures Given at the Santa Fe Complexity Institute Summer School,

1991. Jeffrey Goldstone's name corrected

Journal-ref: 1991 Lectures in Complex Systems, eds. L. Nadel and D. Stein, SFI

Studies in the Sciences of Complexity, Proc. Vol. XV, Addison Wesley, 1992,

p. 243

\\ ( http://arxiv.org/abs/cond-mat/9204009 , 328kb)

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arXiv:0901.4769

replaced with revised version Tue, 16 Jun 2009 19:35:11 GMT (160kb)

Title: Induced interactions for ultracold Fermi gases in optical lattices

Authors: D.-H. Kim, P. T\"orm\"a, J.-P. Martikainen

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

Comments: 4 pages, 4 figures

Journal-ref: Phys. Rev. Lett. 102, 245301 (2009)

DOI: 10.1103/PhysRevLett.102.245301

\\ ( http://arxiv.org/abs/0901.4769 , 160kb)

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arXiv:0812.1387

replaced with revised version Tue, 16 Jun 2009 12:01:55 GMT (565kb)

Title: Effective three-body interactions of neutral bosons in optical lattices

Authors: P.R. Johnson, E. Tiesinga, J.V. Porto, C.J. Williams

Categories: quant-ph

Comments: Expanded version; some issues in the perturbation theory are

corrected and clarified

\\ ( http://arxiv.org/abs/0812.1387 , 565kb)

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arXiv:0902.3964

replaced with revised version Tue, 16 Jun 2009 16:13:28 GMT (927kb,D)

Title: Single photon nonlinearities using arrays of cold polar molecules

Authors: R.M. Rajapakse, T. Bragdon, A.M. Rey, T. Calarco, S. F. Yelin

Categories: quant-ph

Comments: 8 pages, 9 figures Accepted for publication in Physical Review A

\\ ( http://arxiv.org/abs/0902.3964 , 927kb)

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arXiv:0904.4210

replaced with revised version Tue, 16 Jun 2009 15:15:02 GMT (335kb)

Title: Quantum optics with quantum gases: controlled state reduction by

designed light scattering

Authors: Igor B. Mekhov, Helmut Ritsch

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

Comments: updated, to be published in Phys. Rev. A

\\ ( http://arxiv.org/abs/0904.4210 , 335kb)

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arXiv:0904.1552

replaced with revised version Wed, 17 Jun 2009 15:13:54 GMT (464kb)

Title: Pair-supersolid phase in a bilayer system of dipolar lattice bosons

Authors: C. Trefzger, C. Menotti, and M. Lewenstein

Categories: cond-mat.other

Comments: 4 pages, 3 figures

\\ ( http://arxiv.org/abs/0904.1552 , 464kb)

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arXiv:0905.4948

replaced with revised version Wed, 17 Jun 2009 18:04:40 GMT (71kb,D)

Title: Ultracold Gases of Ytterbium: Ferromagnetism and Mott States in an SU(6)

Fermi System

Authors: M. A. Cazalilla, A. F. Ho, and M. Ueda

Categories: cond-mat.quant-gas cond-mat.str-el

Comments: 4+ pages, 1 figure; v2: Improved discussion of the SU(6)

symmetry-breaking patterns

\\ ( http://arxiv.org/abs/0905.4948 , 71kb)

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arXiv:0903.2050

replaced with revised version Tue, 16 Jun 2009 22:03:38 GMT (215kb,D)

Title: Magnetometry via a double-pass continuous quantum measurement of atomic

spin

Authors: Bradley A. Chase, Ben Q. Baragiola, Heather L. Partner, Brigette D.

Black, JM Geremia

Categories: quant-ph

Comments: 17 pages, updated to match print version

Journal-ref: Phys. Rev. A, 79, 062107 (2009)

DOI: 10.1103/PhysRevA.79.062107

\\ ( http://arxiv.org/abs/0903.2050 , 215kb)

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arXiv:0903.1485

replaced with revised version Wed, 17 Jun 2009 09:22:35 GMT (16kb)

Title: Manipulating Higher Partial-Wave Atom-Atom Interaction by Strong

Photoassoiative Coupling

Authors: Bimalendu Deb and Jisha Hazra

Categories: physics.atom-ph physics.optics

Comments: Accepted for publication in Physical Review Letters; 4 pages 1 figure

\\ ( http://arxiv.org/abs/0903.1485 , 16kb)

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arXiv:0808.2565

replaced with revised version Thu, 18 Jun 2009 12:06:16 GMT (132kb)

Title: Localized states and interaction induced delocalization in Bose gases

with quenched disorder

Authors: G.M. Falco, T. Nattermann and V.L. Pokrovsky

Categories: cond-mat.other cond-mat.stat-mech

Comments: 17 pages, 5 figure

Journal-ref: Europhysics Letters {\bf 85}, 30002 (2009)

DOI: 10.1209/0295-5075/85/30002

\\ ( http://arxiv.org/abs/0808.2565 , 132kb)

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arXiv:0809.1056

replaced with revised version Thu, 18 Jun 2009 15:14:10 GMT (190kb)

Title: Groundstatable fermionic wavefunctions and their associated many-body

Hamiltonians

Authors: D. Charrier and C. Chamon

Categories: cond-mat.str-el

Comments: 12 pages, 16 figures, extensively revised

\\ ( http://arxiv.org/abs/0809.1056 , 190kb)

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arXiv:0904.1569

replaced with revised version Wed, 17 Jun 2009 20:54:01 GMT (7084kb)

Title: Induced interaction and crystallization of self-localized impurity

fields in a Bose-Einstein condensate

Authors: Sergio Rica and David C. Roberts

Categories: cond-mat.quant-gas

Comments: v2: movies will be linked from Phys Rev A website; corrected

hysteresis discussion; other minor edits; 16 pages, 9 figures, (32 fig. files

including subfigures)

\\ ( http://arxiv.org/abs/0904.1569 , 7084kb)

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\\

arXiv:0904.2399

replaced with revised version Wed, 17 Jun 2009 20:18:50 GMT (137kb)

Title: Bose-Einstein and Fermi-Dirac distributions in nonextensive quantum

statistics: An exact approach

Authors: Hideo Hasegawa (Tokyo Gakugei Univ.)

Categories: cond-mat.stat-mech cond-mat.other

Comments: 34 pages, 11 figures; augmented the text

\\ ( http://arxiv.org/abs/0904.2399 , 137kb)

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Till next time,

Matt.

-- ========================================================================= Dr M. J. Davis, Associate Professor in Physics School of Mathematics and Physics, ph : +61 7 334 69824 The University of Queensland, fax : +61 7 336 51242 Brisbane, QLD 4072, mdavis_at_physics.uq.edu.au Australia. 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 ========================================================================= _______________________________________________ Matts-arxiv mailing list Matts-arxiv_at_lists.sps.uq.edu.auReceived on Mon Jul 13 2009 - 11:09:56 EST

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