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

Date: Tue, 23 Jun 2009 08:44:08 +1000

Date: Tue, 23 Jun 2009 08:44:08 +1000

Dear subscribers,

Today's mailing was collated by Jacopo Sabbatini. There are 16 new preprints

and 6 replacements:

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arXiv:0905.2600

Date: Fri, 15 May 2009 18:32:08 GMT (59kb)

Title: Stabilization of the p-wave superfluid state in an optical lattice

Authors: Y.-J. Han, Y.-H. Chan, W. Yi, A. J. Daley, S. Diehl, P. Zoller and

L.-M. Duan

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

Comments: 5 pages, 5 figures

\\

It is hard to stabilize the p-wave superfluid state of cold atomic gas in

free space due to inelastic collisional losses. We consider the p-wave Feshbach

resonance in an optical lattice, and show that it is possible to have a stable

p-wave superfluid state where the multi-atom collisional loss is suppressed

through the quantum Zeno effect. We derive the effective Hamiltonian for this

system, and calculate its phase diagram in a one-dimensional optical lattice.

The results show rich phase transitions between the p-wave superfluid state and

different types of insulator states induced either by interaction or by

dissipation.

\\ ( http://arxiv.org/abs/0905.2600 , 59kb)

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arXiv:0905.2610

Date: Mon, 18 May 2009 17:56:58 GMT (1128kb)

Title: Two-orbital SU(N) magnetism with ultracold alkaline-earth atoms

Authors: A. V. Gorshkov, M. Hermele, V. Gurarie, C. Xu, P. S. Julienne, J. Ye,

P. Zoller, E. Demler, M. D. Lukin, A. M. Rey

Categories: cond-mat.quant-gas

Comments: 12 pages, 6 figures

\\

Fermionic alkaline-earth(-like) atoms -- atoms with two valence electrons --

such as 87Sr and 171Yb, have unique properties that make them attractive

candidates for the realization of novel atomic clocks and degenerate quantum

gases. At the same time, they are attracting considerable theoretical attention

in the context of quantum information processing. Here we demonstrate that when

such atoms are loaded in optical lattices, they can be used as quantum

simulators of unique many-body phenomena. In particular, we show that the

decoupling of the nuclear spin from the electronic angular momentum can be used

to implement many-body systems with an unprecedented degree of symmetry,

characterized by the SU(N) group with N as large as 10. Moreover, the interplay

of the nuclear spin with the electronic degree of freedom provided by a stable

optically excited state allows for the study of spin-orbital physics. Such

systems may provide valuable insights into strongly correlated physics of

transition metal oxides, heavy fermion materials, and spin liquid phases.

Experimental techniques for preparing and detecting the resulting phases are

discussed.

\\ ( http://arxiv.org/abs/0905.2610 , 1128kb)

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arXiv:0905.2754

Date: Sun, 17 May 2009 18:04:48 GMT (575kb)

Title: Quantum turbulence at finite temperature: the two-fluids cascade

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

L\'ev\^eque (Phys-ENS)

Categories: cond-mat.other

\\

To model isotropic homogeneous quantum turbulence in superfluid helium, we

have performed Direct Numerical Simulations (DNS) of two fluids (the normal

fluid and the superfluid) coupled by mutual friction. We have found evidence of

strong locking of superfluid and normal fluid along the turbulent cascade, from

the large scale structures where only one fluid is forced down to the vorticity

structures at small scales. We have determined the residual slip velocity

between the two fluids, and, for each fluid, the relative balance of inertial,

viscous and friction forces along the scales. Our calculations show that the

classical relation between energy injection and dissipation scale is not valid

in quantum turbulence, but we have been able to derive a temperature--dependent

superfluid analogous relation. Finally, we discuss our DNS results in terms of

the current understanding of quantum turbulence, including the value of the

effective kinematic viscosity.

\\ ( http://arxiv.org/abs/0905.2754 , 575kb)

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arXiv:0905.2826

Date: Mon, 18 May 2009 08:37:34 GMT (58kb)

Title: All-optical pump-and-probe detection of dynamical correlations in a

two-dimensional Fermi gas

Authors: Tung-Lam Dao, Corinna Kollath, Iacopo Carusotto, Michael Koehl

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

Comments: 4 pages, 4 figures

\\

We propose an all-optical scheme to probe the dynamical correlations of a

strongly-interacting gas of ultracold atoms. The proposed technique is based on

a pump-and-probe scheme: a coherent light pulse is initially converted into an

atomic coherence and later retrieved after a variable storage time. The

efficiency of the proposed method to measure the one-particle Green function of

the gas is validated by numerical and analytical calculations of the expected

signal for the two cases of a normal Fermi gas and a BCS superfluid state.

Protocols to extract the superfluid gap and the full quasi-particle dispersions

are discussed.

\\ ( http://arxiv.org/abs/0905.2826 , 58kb)

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arXiv:0905.2832

Date: Mon, 18 May 2009 08:56:49 GMT (13kb)

Title: Mixtures of Bose gases confined in a ring potential

Authors: J. Smyrnakis, G. M. Kavoulakis, M. Magiropoulos, K. K\"arkk\"ainen, S.

M. Reimann

Categories: cond-mat.quant-gas

Comments: 4 pages, 1 figure

\\

We examine the ground state and the rotational properties of a mixture of two

distinguishable Bose gases that are confined in a ring potential. Persistent

currents are shown to be stable for a range of the population imbalance between

the two components at low angular momentum. At higher values of the angular

momentum even small admixtures of a second species of atoms make the persistent

currents highly fragile.

\\ ( http://arxiv.org/abs/0905.2832 , 13kb)

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arXiv:0905.2838

Date: Mon, 18 May 2009 11:31:08 GMT (398kb,D)

Title: Fractional photon-assisted tunneling for Bose-Einstein condensates in a

double well

Authors: Niklas Teichmann, Martin Esmann, and Christoph Weiss

Categories: cond-mat.quant-gas cond-mat.other

Comments: 7 pages, 5 figures

\\

Half-integer photon-resonances in a periodically shaken double well are

investigated on the level of the N-particle quantum dynamics. Contrary to

non-linear mean-field equations, the linear N-particle Schrodinger equation

does not contain any non-linearity which could be the origin of such

resonances. Nevertheless, analytic calculations on the N-particle level explain

why such resonances can be observed even for particle numbers as low as N = 2.

These calculations also demonstrate why fractional photon resonances are not

restricted to half-integer values.

\\ ( http://arxiv.org/abs/0905.2838 , 398kb)

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arXiv:0905.2723

Date: Sun, 17 May 2009 08:55:31 GMT (14kb)

Title: Schr\"odinger's cat meets Occam's razor

Authors: Richard D. Gill

Categories: quant-ph

\\

We discuss V.P. Belavkin's approach to the measurement problem encapsulated

in his theory of eventum mechanics (as presented in his 2007 survey). In

particular, we show its relation to ideas based on superselection and

interaction with the environment developed by N.P. Landsman (1995, and more

recent papers).

Landsman writes "those believing that the classical world exists

intrinsically and absolutely [such persons later termed by him B-realists] are

advised against reading this [his, 1995] paper". He adopts a milder position,

calling it that of an A-realist: we live in a classical world but to give it

special status is like insisting that the Earth is the centre of the universe.

The B-realists are accused of living under some kind of hallucination. Landsman

presents arguments pointing in a particular direction to a resolution of the

measurement problem which at least would satisfy the A-realists. We point out

in this paper that the theory earlier developed by Belavkin (surveyed in his

2007 paper) seems to complete Landsman's program or at least exhibits a

"realisation" satisfying his desiderata. At the same time it seems that this

completion of the program ends up giving both A- and B-realists equal licence

to accuse the others of living under hallucinations.

\\ ( http://arxiv.org/abs/0905.2723 , 14kb)

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arXiv:0905.2963

Date: Mon, 18 May 2009 20:00:07 GMT (1229kb,D)

Title: Observation of elastic doublon decay in the Fermi-Hubbard model

Authors: Niels Strohmaier, Daniel Greif, Robert J\"ordens, Leticia Tarruell,

Henning Moritz, Tilman Esslinger, Rajdeep Sensarma, David Pekker, Ehud

Altman, Eugene Demler

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

\\

We investigate the decay of highly excited states of ultracold fermions in a

three-dimensional optical lattice. Starting from a repulsive Fermi-Hubbard

system near half filling, we generate additional doubly occupied sites

(doublons) by lattice modulation. The subsequent relaxation back to thermal

equilibrium is monitored over time. The measured doublon lifetime covers two

orders of magnitude. In units of the tunneling time h/J it is found to depend

exponentially on the ratio of on-site interaction energy U to kinetic energy J.

We argue that the dominant mechanism for the relaxation is a high order

scattering process involving several single fermions as scattering partners. A

many-body calculation is carried out using diagrammatic methods, yielding good

agreement with the data.

\\ ( http://arxiv.org/abs/0905.2963 , 1229kb)

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arXiv:0905.3035

Date: Tue, 19 May 2009 07:23:15 GMT (176kb)

Title: Energy bands and Landau levels of ultracold fermions in the bilayer

honeycomb optical lattice

Authors: Jing-Min Hou

Categories: cond-mat.quant-gas cond-mat.other

Comments: To appear in Journal of Modern Optics

\\

We investigate the spectrum and eigenstates of ultracold fermionic atoms in

the bilayer honeycomb optical lattice. In the low energy approximation, the

dispersion relation has parabolic form and the quasiparticles are chiral. In

the presence of the effective magnetic field, which is created for the system

with optical means, the energy spectrum shows an unconventional Landau level

structure. Furthermore, the experimental detection of the spectrum is proposed

with the Bragg scattering techniques.

\\ ( http://arxiv.org/abs/0905.3035 , 176kb)

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arXiv:0905.3068

Date: Tue, 19 May 2009 11:36:14 GMT (8kb)

Title: Generation of nonground-state condensates and adiabatic paradox

Authors: V.I. Yukalov and V.S. Bagnato

Categories: cond-mat.quant-gas cond-mat.mes-hall

Comments: Latex file, 10 pages

Journal-ref: Laser Phys. Lett. 6 (2009) 399-403

\\

The problem of resonant generation of nonground-state condensates is

addressed aiming at resolving the seeming paradox that arises when one resorts

to the adiabatic representation. In this picture, the eigenvalues and

eigenfunctions of a time-dependent Gross-Pitaevskii Hamiltonian are also

functions of time. Since the level energies vary in time, no definite

transition frequency can be introduced. Hence no external modulation with a

fixed frequency can be made resonant. Thus, the resonant generation of

adiabatic coherent modes is impossible. However, this paradox occurs only in

the frame of the adiabatic picture. It is shown that no paradox exists in the

properly formulated diabatic representation. The resonant generation of

diabatic coherent modes is a well defined phenomenon. As an example, the

equations are derived, describing the generation of diabatic coherent modes by

the combined resonant modulation of the trapping potential and atomic

scattering length.

\\ ( http://arxiv.org/abs/0905.3068 , 8kb)

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arXiv:0905.3207

Date: Wed, 20 May 2009 01:14:18 GMT (238kb)

Title: Density-functional theory of two-component Bose gases in one-dimensional

harmonic traps

Authors: Yajiang Hao, Shu Chen

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

Comments: 8 pages, 5 figures

\\

We investigate the ground-state properties of two-component Bose gases

confined in one-dimensional harmonic traps in the scheme of density-functional

theory. The density-functional calculations employ a Bethe-ansatz-based

local-density approximation for the correlation energy, which accounts for the

correlation effect properly in the full physical regime. For the binary Bose

mixture with spin-independent interaction, the homogeneous reference system is

exactly solvable by the Bethe-ansatz method. Within the local-density

approximation, we determine the density distribution of each component and

study its evolution from Bose distributions to Fermi-like distribution with the

increase in interaction. For the binary mixture of Tonks-Girardeau gases with a

tunable inter-species repulsion, with a generalized Bose-Fermi transformation

we show that the Bose mixture can be mapped into a two-component Fermi gas,

which corresponds to exact soluble Yang-Gaudin model for the homogeneous

system. Based on the ground-state energy function of the Yang-Gaudin model, the

ground-state density distributions are calculated for various inter-species

interactions. It is shown that with the increase in inter-species interaction,

the system exhibits composite-fermionization crossover.

\\ ( http://arxiv.org/abs/0905.3207 , 238kb)

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arXiv:0905.3312

Date: Wed, 20 May 2009 14:23:31 GMT (28kb)

Title: Correlation dynamics of strongly-correlated bosons out of equilibrium

induced by a lattice time-modulation

Authors: Karen Rodriguez, Arturo Arg\"uelles and Luis Santos

Categories: cond-mat.quant-gas cond-mat.other

Comments: 6 pages, 8 figures

\\

We analyse by means of Matrix Product States techniques the dynamics of

strongly-correlated Bose gases in a finite one-dimensional optical lattice

during a change of the lattice parameters within the superfluid region. We

analyse different regimes of perturbation, which range from adiabatic to

non-adiabatic. In particular, we are interested in the evolution of the system

correlations on time, showing that the each correlation presents different time

scales in their response to the lattice modulation. As a consequence, when

local quantities have converged, the long-range correlations and the

quasi-condensate fraction may still present a significant dynamics. In

addition, the different time scales for several correlations open the

possibility to have a well defined criterion for adiabaticity in the system.

\\ ( http://arxiv.org/abs/0905.3312 , 28kb)

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arXiv:0905.3251

Date: Wed, 20 May 2009 09:12:21 GMT (230kb)

Title: Pump-probe spectroscopy of two-body correlations in ultracold gases

Authors: Christiane P. Koch, Ronnie Kosloff

Categories: quant-ph cond-mat.quant-gas

\\

We suggest pump-probe spectroscopy to study pair correlations that determine

the many-body dynamics in weakly interacting, dilute ultracold gases. A

suitably chosen, short laser pulse depletes the pair density locally, creating

a 'hole' in the electronic ground state. The dynamics of this non-stationary

pair density is monitored by a time-delayed probe pulse. The resulting

transient signal allows to spectrally decompose the 'hole' and to map out the

pair correlation functions.

\\ ( http://arxiv.org/abs/0905.3251 , 230kb)

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arXiv:0905.3384

Date: Wed, 20 May 2009 20:00:28 GMT (452kb)

Title: Representation of quantum dynamics of interacting systems through

classical trajectories

Authors: Anatoli Polkovnikov

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

Comments: 82 pages (single column), 17 figures

\\

We formulate representation of quantum dynamics of many-particle interacting

systems through classical trajectories as a perturbative expansion in quantum

fluctuations around the classical limit. We explicitly consider three different

classical limits in the coordinate-momentum representation (corpuscular

classical limit), coherent state representation (wave classical limit), and the

classical limit for spin systems. We describe how one recovers truncated Wigner

approximation (TWA) in the leading order in quantum fluctuations around each of

these limits. Further quantum corrections can be found either in the form of

non-linear response of observables to infinitesimal quantum jumps or

equivalently in terms of stochastic quantum jumps with non-positive weight. We

discuss how one can find both equal and non-equal time correlation functions

within this approach and which correlation functions have casual

representation. Our approach is closely related to phase space methods based on

Weyl quantization, coherent state phase space methods, and Keldysh diagrammatic

technique. We show how both new results and earlier concepts naturally emerge

from combining path-integral approach and the Heisenberg representation. We

illustrate this approach with various examples including sine-Gordon model,

one- and two-dimensional Bose Hubbard model, Dicke model and others.

\\ ( http://arxiv.org/abs/0905.3384 , 452kb)

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arXiv:0905.3547

Date: Thu, 21 May 2009 19:28:15 GMT (328kb)

Title: Evolution of squeezed states under the Fock-Darwin Hamiltonian

Authors: Jaime E. Santos, Nuno M. Peres, Joao Lopes dos Santos

Categories: cond-mat.quant-gas cond-mat.other

\\

We develop a complete analytical description of the time evolution of

squeezed states of a charged particle under the Fock-Darwin Hamiltonian and a

time-dependent electric field. This result generalises a relation obtained by

Infeld and Pleba\'nski for states of the one-dimensional harmonic oscillator.

We relate the evolution of a state-vector subjected to squeezing to that of

state which is not subjected to squeezing and for which the time-evolution

under the simple harmonic oscillator dynamics is known (e.g. an eigenstate of

the Hamiltonian). A corresponding relation is also established for the Wigner

functions of the states, in view of their utility in the analysis of cold-ion

experiments. In an appendix, we compute the response functions of the FD

Hamiltonian to an external electric field, using the same techniques as in the

main text.

\\ ( http://arxiv.org/abs/0905.3547 , 328kb)

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arXiv:0905.3541

Date: Thu, 21 May 2009 18:20:05 GMT (152kb)

Title: Dispersive propagation of ultraslow light in an atomic Bose-Einstein

condensate

Authors: Devrim Tarhan, Seckin Sefi, and Ozgur E. Mustecaplioglu

Categories: physics.optics

Comments: 14 pages, 3 figures

\\

One dimensional propagation of ultraslow optical pulses in an atomic

Bose-Einstein condensate taking into account the dispersion and the spatial

inhomogeneity is investigated. Analytical and semi-analytical solutions of the

dispersive inhomogeneous wave equation modeling the ultraslow pulse propagation

are developed and compared against the standard wave equation solvers based

upon Cranck-Nicholson and pseudo-spectral methods. The role of curvature of the

trapping potential of the condensate on the amount of dispersion of the

ultraslow pulse is pointed out.

\\ ( http://arxiv.org/abs/0905.3541 , 152kb)

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The replacements:

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arXiv:0705.3217

replaced with revised version Fri, 15 May 2009 07:50:09 GMT (211kb)

Title: Nonclassicality in phase space and nonclassical correlation

Authors: Petr Marek, M. S. Kim and Jinhyoung Lee

Categories: quant-ph

Comments: 5 pages, 4 figures, replaced by the published version

Journal-ref: Phys. Rev. A 79, 052315 (2009)

\\ ( http://arxiv.org/abs/0705.3217 , 211kb)

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arXiv:0901.2943

replaced with revised version Sat, 16 May 2009 12:04:35 GMT (35kb,D)

Title: Ground state energy of the two-dimensional weakly interacting Bose gas:

First correction beyond Bogoliubov theory

Authors: Christophe Mora, Yvan Castin

Categories: cond-mat.stat-mech

Comments: 4 pages, 1 figure, published in Phys. Rev. Lett

Journal-ref: Phys. Rev. Lett. 102, 180404 (2009)

DOI: 10.1103/PhysRevLett.102.180404

\\ ( http://arxiv.org/abs/0901.2943 , 35kb)

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arXiv:0805.0105

replaced with revised version Tue, 19 May 2009 18:28:06 GMT (129kb)

Title: Interference of Bose-Einstein condensates: quantum non-local effects

Authors: William W.J. Mullin (UMASS), Franck Lalo\"e (LKB - Lhomond)

Categories: quant-ph cond-mat.other

Comments: version published in Phys Rev

Journal-ref: Physical Review A: Atomic, Molecular and Optical Physics A78

(2008) 061605

DOI: 10.1103/PhysRevA.78.061605

\\ ( http://arxiv.org/abs/0805.0105 , 129kb)

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arXiv:0812.2736

replaced with revised version Tue, 19 May 2009 13:49:43 GMT (286kb)

Title: Skyrmion in spinor condensates and its stability in trap potentials

Authors: Akiyuki Tokuno, Yohei Mitamura, Masaki Oshikawa, Igor F. Herbut

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

Comments: 12 pages, 9 figures, final version

Journal-ref: Phys. Rev. A 79, 053626 (2009)

DOI: 10.1103/PhysRevA.79.053626

\\ ( http://arxiv.org/abs/0812.2736 , 286kb)

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arXiv:0901.2807

replaced with revised version Tue, 19 May 2009 07:23:33 GMT (472kb)

Title: Occupation Statistics of a BEC for a Driven Landau-Zener Crossing

Authors: Katrina Smith-Mannschott, Maya Chuchem, Moritz Hiller, Tsampikos

Kottos, Doron Cohen

Categories: cond-mat.other

Comments: 4 pages, 5 figures

\\ ( http://arxiv.org/abs/0901.2807 , 472kb)

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arXiv:0902.0366

replaced with revised version Mon, 18 May 2009 22:25:28 GMT (18kb)

Title: Ground State Properties of Cold Bosonic Atoms At Large Scattering

Lengths

Authors: Jun Liang Song, Fei Zhou (UBC)

Categories: cond-mat.other

Comments: 4 pages, 3 figures, accepted by PRL

\\ ( http://arxiv.org/abs/0902.0366 , 18kb)

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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 Fri Jul 31 2009 - 11:19:13 EST

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