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

Date: Fri, 27 Apr 2007 15:27:55 +1000 (EST)

Date: Fri, 27 Apr 2007 15:27:55 +1000 (EST)

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

You can tell I've been busy as the arXiv selection is late again. This

week we have 31 new abstracts and 10 replacements.

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arXiv:0704.1708

Date: Fri, 13 Apr 2007 07:30:52 GMT (59kb)

Title: Is there least action principle in stochastic dynamics?

Authors: Qiuping A. Wang (ISMANS)

Categories: cond-mat.stat-mech

Comments: 10 pages

Proxy: ccsd hal-00141482

\\

On the basis of the work showing that the maximum entropy principle for

equilibrium mechanical system is a consequence of the principle of virtual

work, i.e., the virtual work of random forces on a mechanical system should

vanish in thermodynamic equilibrium, we present in this paper a development of

the same principle for the dynamical system out of equilibrium. One of the

objectives of the present work is to justify a least action principle we

postulated previously for stochastic mechanical systems.

\\ ( http://arxiv.org/abs/0704.1708 , 59kb)

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arXiv:0704.1735

Date: Fri, 13 Apr 2007 11:25:00 GMT (16kb)

Title: Calorimetry of Bose-Einstein condensates

Authors: P. B. Blakie, E. Toth, M. J. Davis

Categories: cond-mat.other

Comments: 6 pages, 1 figure

\\

We outline a practical scheme for measuring the thermodynamic properties of a

Bose-Einstein condensate as a function of internal energy. We propose using

Bragg scattering and controlled trap manipulations to impart a precise amount

of energy to a near zero temperature condensate. After thermalisation the

temperature can be measured using standard techniques to determine the state

equation $T(U,N,\omega)$. Our analysis accounts for interaction effects and the

excitation of constants of motion which restrict the energy available for

thermalisation.

\\ ( http://arxiv.org/abs/0704.1735 , 16kb)

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arXiv:0704.1804

Date: Fri, 13 Apr 2007 18:09:58 GMT (100kb)

Title: Equation of state of atomic systems beyond s-wave determined by the

lowest order constrained variational method: Large scattering length limit

Authors: Ryan M. Kalas, D. Blume

Categories: cond-mat.other

Comments: 10 pages, 7 figures

\\

Dilute Fermi systems with large s-wave scattering length a_s exhibit

universal properties if the interparticle spacing r_o greatly exceeds the range

of the underlying two-body interaction potential. In this regime, r_o is the

only relevant length scale and observables such as the energy per particle

depend only on r_o (or, equivalently, the energy E_{FG} of the free Fermi gas).

This paper investigates Bose and Fermi systems with non-vanishing angular

momentum l using the lowest order constrained variational method. We focus on

the regime where the generalized scattering length becomes large and determine

the relevant length scales. For Bose gases with large generalized scattering

lengths, we obtain simple expressions for the energy per particle in terms of a

l-dependent length scale \xi_l, which depends on the range of the underlying

two-body potential and the average interparticle spacing. We discuss possible

implications for dilute two-component Fermi systems with finite l. Furthermore,

we determine the equation of state of liquid and gaseous bosonic helium.

\\ ( http://arxiv.org/abs/0704.1804 , 100kb)

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arXiv:0704.1686

Date: Fri, 13 Apr 2007 02:54:37 GMT (757kb)

Title: Effect of atomic beam alignment on photon correlation measurements in

cavity QED

Authors: L. Horvath and H. J. Carmichael

Categories: quant-ph

Comments: 15 pages and 13 figures

\\

Quantum trajectory simulations of a cavity QED system comprising an atomic

beam traversing a standing-wave cavity are carried out. The delayed photon

coincident rate for forwards scattering is computed and compared with the

measurements of Rempe et al. [Phys. Rev. Lett. 67, 1727 (1991)] and Foster et

al. [Phys. Rev. A 61, 053821 (2000)]. It is shown that a moderate atomic beam

misalignment can account for the degradation of the predicted correlation. Fits

to the experimental data are made in the weak-field limit with a single

adjustable parameter--the atomic beam tilt from perpendicular to the cavity

axis. Departures of the measurement conditions from the weak-field limit are

discussed.

\\ ( http://arxiv.org/abs/0704.1686 , 757kb)

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arXiv:0704.1881

Date: Sat, 14 Apr 2007 16:43:25 GMT (354kb)

Title: Statistical Properties of Many Particle Eigenfunctions

Authors: Eric J. Heller and Brian R. Landry

Categories: quant-ph

Comments: 13 pages, 4 figures

\\

Wavefunction correlations and density matrices for few or many particles are

derived from the properties of semiclassical energy Green functions. Universal

features of fixed energy (microcanonical) random wavefunction correlation

functions appear which reflect the emergence of the canonical ensemble as the

number of particles approaches infinity. This arises through a little known

asymptotic limit of Bessel functions. Constraints due to symmetries,

boundaries, and collisions between particles can be included.

\\ ( http://arxiv.org/abs/0704.1881 , 354kb)

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arXiv:0704.1896

Date: Sun, 15 Apr 2007 07:26:51 GMT (31kb)

Title: Path Distinguishability in Double Scattering of Light by Atoms

Authors: Christian Miniatura, Cord A. M\"uller, Yin Lu, Guangquan Wang,

Berthold-Georg Englert

Categories: quant-ph

Comments: 4 pages, 1 figure

\\

Wave-particle duality finds a natural application for electrons or light

propagating in disordered media where coherent corrections to transport are

given by two-wave interference. For scatterers with internal degrees of

freedom, these corrections are observed to be much smaller than would be

expected for structureless scatterers. By examining the basic example of the

scattering of one photon by two spin-1/2 atoms--a case-study for coherent

backscattering--we demonstrate that the loss of interference strength is

associated with which-path information stored by the scattering atoms.

\\ ( http://arxiv.org/abs/0704.1896 , 31kb)

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arXiv:0704.1880

Date: Mon, 16 Apr 2007 15:34:49 GMT (54kb)

Title: Quantum Quenches in Extended Systems

Authors: Pasquale Calabrese, John Cardy

Categories: cond-mat.stat-mech

Comments: 23 Pages, 4 figures

\\

We study in general the time-evolution of correlation functions in a extended

quantum system after the quench of a parameter in the hamiltonian. We show that

correlation functions in d dimensions can be extracted using methods of

boundary critical phenomena in d+1 dimensions. For d=1 this allows to use the

powerful tools of conformal field theory in the case of critical evolution.

Several results are obtained in generic dimension in the gaussian (mean-field)

approximation. These predictions are checked against the real-time evolution of

some solvable models that allows also to understand which features are valid

beyond the critical evolution.

All our findings may be explained in terms of a picture generally valid,

whereby quasiparticles, entangled over regions of the order of the correlation

length in the initial state, then propagate with a finite speed through the

system. Furthermore we show that the long-time results can be interpreted in

terms of a generalized Gibbs ensemble. We discuss some open questions and

possible future developments.

\\ ( http://arxiv.org/abs/0704.1880 , 54kb)

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arXiv:0704.1889

Date: Sun, 15 Apr 2007 00:02:39 GMT (41kb)

Title: First and second sound modes at finite temperature in trapped Fermi

gases from BCS to BEC

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

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

Comments: 4 pages, 3 figures

\\

We determine the temperature $T$ dependence of first and second sound mode

frequencies for trapped Fermi gases undergoing BCS to Bose Einstein

condensation (BEC) crossover. Our results, based on the two fluid equations,

show that the lowest radial breathing mode is nearly $T$ independent as in

experiment, most strikingly at unitarity, but on the near-BCS and near-BEC

sides as well. At finite $T$, higher order breathing modes are predicted to

strongly mix with second sound. Their complex $T$ dependence should provide a

signature of superfluidity.

\\ ( http://arxiv.org/abs/0704.1889 , 41kb)

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arXiv:0704.1953

Date: Mon, 16 Apr 2007 09:04:32 GMT (157kb)

Title: Ramsey fringes formation during excitation of topological modes in a

Bose-Einstein condensate

Authors: E.R.F. Ramos, L. Sanz, V.I. Yukalov, and V.S. Bagnato

Categories: cond-mat.stat-mech cond-mat.mes-hall

Comments: Latex file, 12 pages, 5 figures

Journal-ref: Phys. Lett. A 365 (2007) 126-130

\\

The Ramsey fringes formation during the excitation of topological coherent

modes of a Bose-Einstein condensate by an external modulating field is

considered. The Ramsey fringes appear when a series of pulses of the excitation

field is applied. In both Rabi and Ramsey interrogations, there is a shift of

the population maximum transfer due to the strong non-linearity present in the

system. It is found that the Ramsey pattern itself retains information about

the accumulated relative phase between both ground and excited coherent modes.

\\ ( http://arxiv.org/abs/0704.1953 , 157kb)

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arXiv:0704.1971

Date: Mon, 16 Apr 2007 10:05:11 GMT (189kb)

Title: Dissipative dynamics of superfluid vortices at non-zero temperatures

Authors: Natalia G. Berloff and Anthony J. Youd

Categories: cond-mat.soft

Comments: 4 pages, 3 figures

\\

We consider the evolution and dissipation of vortex rings in a condensate at

non-zero temperature, in the context of the classical field approximation,

based on the defocusing nonlinear Schr\"odinger equation. The temperature in

such a system is fully determined by the total number density and the number

density of the condensate. A vortex ring is introduced into a condensate in a

state of thermal equilibrium, and interacts with non-condensed particles. These

interactions lead to a gradual decrease in the vortex line density, until the

vortex ring completely disappears. We show that the square of the vortex line

density changes linearly with time, and obtain the corresponding universal

decay law, which gives an exponential dependence on temperature.

\\ ( http://arxiv.org/abs/0704.1971 , 189kb)

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arXiv:0704.1995

Date: Mon, 16 Apr 2007 12:19:13 GMT (85kb)

Title: Coherent dynamics of domain formation in the Bose Ferromagnet

Authors: Qiang Gu, Haibo Qiu, Kai Bongs, Klaus Sengstock

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

Comments: 4 pages, 3 figures, Accepted for publishing in PRL

\\

We present a theory to describe domain formation observed very recently in a

quenched Rb-87 gas, a typical ferromagnetic spinor Bose system. An overlap

factor is introduced to characterize the symmetry breaking of M_F=\pm 1

components for the F=1 ferromagnetic condensate. We demonstrate that the domain

formation is a co-effect of the quantum coherence and the thermal relaxation. A

thermally enhanced quantum-oscillation is observed during the dynamical process

of the domain formation. And the spatial separation of domains leads to

significant decay of the M_F=0 component fraction in an initial M_F=0

condensate.

\\ ( http://arxiv.org/abs/0704.1995 , 85kb)

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arXiv:0704.2054

Date: Sun, 15 Apr 2007 21:39:23 GMT (1197kb,D)

Title: Vortex Formation by Merging and Interference of Multiple Trapped

Bose-Einstein Condensates

Authors: David R. Scherer

Categories: cond-mat.other

Comments: Ph.D. dissertation submitted to the University of Arizona, 178 pages

including 53 heavily compressed images; high resolution version is available

at http://www.optics.arizona.edu/Anderson/

\\

An apparatus for producing atomic-gas Bose-Einstein condensates (BECs) of

87-Rb atoms is described. The apparatus produces 87-Rb BECs in a dual-chamber

vacuum system that incorporates magnetic transport of trapped atoms from the

magneto-optical trapping cell to the BEC production cell via the operation of a

series of overlapping magnet coils. The design, construction, and operation of

the apparatus are described in detail. The apparatus is used to study the

creation of quantized vortices in BECs by the merging and interference of

multiple trapped condensates. In this experiment, a single harmonic potential

well is partitioned into three sections by an optical barrier, enabling the

simultaneous formation of three independent, uncorrelated BECs. The BECs may

either merge together during their growth, or, for high-energy barriers, the

BECs can be merged together by barrier removal after their formation. Either

process may instigate vortex formation in the resulting BEC, depending on the

initially indeterminate relative phases of the condensates and the merging

rate.

\\ ( http://arxiv.org/abs/0704.2054 , 1197kb)

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arXiv:0704.1974

Date: Mon, 16 Apr 2007 10:36:55 GMT (225kb)

Title: Agile low phase noise radio-frequency sine wave generator applied to

experiments on ultracold atoms

Authors: Olivier Morizot (LPL), Julien De Lapeyre De Bellair (LPL), Fabrice

Wiotte (LPL), Olivier Lopez (LPL), Paul-Eric Pottie (LPL), H\'el\`ene Perrin

(LPL)

Categories: physics.atom-ph

Comments: 10 pages, 6 figures

Proxy: ccsd hal-00141806

\\

We report on the frequency performance of a low cost (~500$) radio-frequency

sine wave generator, using direct digital synthesis (DDS) and a

field-programmable gate array (FPGA). The output frequency of the device may be

changed dynamically to any arbitrary value ranging from DC to 10 MHz without

any phase slip. Sampling effects are substantially reduced by a high sample

rate, up to 1 MHz, and by a large memory length, more than 2.10^5 samples. By

using a low noise external oscillator to clock the DDS, we demonstrate a phase

noise as low as that of the master clock, that is at the level of -113

dB.rad^2/Hz at 1 Hz from the carrier for an output frequency of 3.75 MHz. The

device is successfully used to confine an ultracold atomic cloud of rubidium 87

in a RF-based trap, and there is no extra heating from the RF source.

\\ ( http://arxiv.org/abs/0704.1974 , 225kb)

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arXiv:0704.2082

Date: Tue, 17 Apr 2007 00:51:01 GMT (235kb)

Title: Direct measurement of quantum phase gradients in superfluid 4He flow

Authors: Yuki Sato, Aditya Joshi, and Richard Packard

Categories: cond-mat.supr-con

\\

We report a new kind of experiment in which we generate a known superfluid

velocity in a straight tube and directly determine the phase difference across

the tube's ends using a superfluid matter wave interferometer. By so doing, we

quantitatively verify the relation between the superfluid velocity and the

phase gradient of the condensate macroscopic wave function. Within the

systematic error of the measurement (~10%) we find v_s=(hbar/m_4)*(grad phi).

\\ ( http://arxiv.org/abs/0704.2082 , 235kb)

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arXiv:0704.2155

Date: Tue, 17 Apr 2007 13:58:51 GMT (65kb)

Title: Atom-molecule Rabi oscillations in a Mott insulator

Authors: N. Syassen, D. M. Bauer, M. Lettner, D. Dietze, T. Volz, S. D\"urr,

and G. Rempe

Categories: cond-mat.stat-mech

\\

We observe large-amplitude Rabi oscillations between an atomic and a

molecular state near a Feshbach resonance. The experiment uses 87Rb in an

optical lattice and a Feshbach resonance near 414 G. The frequency and

amplitude of the oscillations depend on magnetic field in a way that is well

described by a two-level model. The observed density dependence of the

oscillation frequency agrees with the theoretical expectation. We confirmed

that the state produced after a half-cycle contains exactly one molecule at

each lattice site. In addition, we show that for energies in a gap of the

lattice band structure, the molecules cannot dissociate.

\\ ( http://arxiv.org/abs/0704.2155 , 65kb)

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arXiv:0704.2097

Date: Tue, 17 Apr 2007 05:08:46 GMT (430kb)

Title: Effects of Measurement back-action in the stabilization of a

Bose-Einstein condensate through feedback

Authors: S.D.Wilson, A.R.R.Carvalho, J.J.Hope and M.R.James

Categories: quant-ph

Comments: 1 Tex, 4 PS pictures, 1 bbl file

\\

We apply quantum filtering and control to a particle in a harmonic trap under

continuous position measurement, and show that a simple static feedback law can

be used to cool the system. The final steady state is Gaussian and dependent on

the feedback strength and coupling between the system and probe. In the limit

of weak coupling this final state becomes the ground state. An earlier model by

Haine et. al. (PRA 69, 2004) without measurement back-action showed dark

states: states that did not display error signals, thus remaining unaffected by

the control. This paper shows that for a realistic measurement process this is

not true, which indicates that a Bose-Einstein condensate may be driven towards

the ground state from any arbitrary initial state.

\\ ( http://arxiv.org/abs/0704.2097 , 430kb)

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arXiv:0704.2194

Date: Tue, 17 Apr 2007 16:43:30 GMT (6kb)

Title: Casimir Friction I: Friction of vacuum on spinning dielectric

Authors: Yves Pomeau and David C. Roberts

Categories: quant-ph

Comments: campanion article to cond-mat/0503757

\\

We introduce the concept of Casimir friction, i.e. friction due to quantum

fluctuations. In this first article we describe the calculation of a constant

torque, arising from the scattering of quantum fluctuations, on a dielectric

rotating in an electromagnetic vacuum.

\\ ( http://arxiv.org/abs/0704.2194 , 6kb)

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arXiv:0704.1382 (*cross-listing*)

Date: Wed, 11 Apr 2007 09:39:45 GMT (119kb)

Title: Effects of atomic interactions on Quantum Accelerator Modes

Authors: Laura Rebuzzini, Roberto Artuso, Shmuel Fishman and Italo Guarneri.

Categories: nlin.CD quant-ph

Comments: 4 pages, 6 figures

\\

We consider the influence of the inclusion of interatomic interactions on the

delta-kicked accelerator model. Our analysis concerns in particular quantum

accelerator modes, namely quantum ballistic transport near quantal resonances.

The atomic interaction is modelled by a Gross-Pitaevskii cubic nonlinearity,

and we address both attractive (focusing) and repulsive (defocusing) cases. The

most remarkable effect is enhancement or damping of the accelerator modes,

depending on the sign of the nonlinear parameter. We provide arguments showing

that the effect persists beyond mean-field description, and lies within the

experimentally accessible parameter range.

\\ ( http://arxiv.org/abs/0704.1382 , 119kb)

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arXiv:0704.2151

Date: Tue, 17 Apr 2007 13:42:17 GMT (46kb)

Title: Spectroscopy of atomic rubidium at 500 bar buffer gas pressure:

approaching the thermal equilibrium of dressed atom-light states

Authors: U. Vogl and M. Weitz

Categories: physics.atom-ph

Comments: 4 pages

\\

We have recorded fluorescence spectra of the atomic rubidium D-lines in the

presence of several hundreds of bars buffer gas pressure. With additional

saturation broadening a spectral linewidth comparable to the thermal energy of

the atoms in the heated gas cell is achieved. An intensity-dependent blue

asymmetry of the spectra is observed, which becomes increasingly pronounced

when extrapolating to infinitely high light intensity. We interpret our results

as evidence for the dressed (coupled atom-light) states to approach thermal

equilibrium.

\\ ( http://arxiv.org/abs/0704.2151 , 46kb)

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arXiv:0704.2310

Date: Wed, 18 Apr 2007 10:10:01 GMT (25kb)

Title: Mesoscopic Fluctuations of the Pairing Gap

Authors: H. Olofsson, S. \AA berg & P. Leboeuf

Categories: cond-mat.supr-con

Comments: 4 pages, 2 figures

\\

Superfluidity and superconductivity are genuine many-body manifestations of

quantum coherence. For finite-size systems the associated pairing gap

fluctuates as a function of size or shape. We provide a parameter free

theoretical description of pairing fluctuations in mesoscopic systems

characterized by order/chaos dynamics. The theory accurately describes

experimental observations of nuclear superfluidity (regular system), predicts

universal fluctuations of superconductivity in small chaotic metallic grains,

and provides a global analysis in ultracold Fermi gases.

\\ ( http://arxiv.org/abs/0704.2310 , 25kb)

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arXiv:0704.2373

Date: Wed, 18 Apr 2007 16:02:53 GMT (32kb)

Title: Mixing-demixing transition and collapse of a vortex state in a

quasi-two-dimensional boson-fermion mixture

Authors: Sadhan K. Adhikari and Luca Salasnich

Categories: cond-mat.other

Comments: 9 pages, 11 figures

\\

We investigate the mixing-demixing transition and the collapse in a

quasi-two-dimensional degenerate boson-fermion mixture (DBFM) with a bosonic

vortex. We solve numerically a quantum-hydrodynamic model based on a new

density functional which accurately takes into account the dimensional

crossover. It is demonstrated that with the increase of interspecies repulsion,

a mixed state of DBFM could turn into a demixed state. The system collapses for

interspecies attraction above a critical value which depends on the vortex

quantum number. For interspecies attraction just below this critical limit

there is almost complete mixing of boson and fermion components. Such mixed and

demixed states of a DBFM could be experimentally realized by varying an

external magnetic field near a boson-fermion Feshbach resonance, which will

result in a continuous variation of interspecies interaction.

\\ ( http://arxiv.org/abs/0704.2373 , 32kb)

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arXiv:0704.2412

Date: Wed, 18 Apr 2007 19:46:10 GMT (152kb)

Title: Giant viscosity enhancement in a spin-polarized Fermi liquid

Authors: H. Akimoto, J. S. Xia, D. Candela, W. J. Mullin, E. D. Adams, and N.

S. Sullivan

Categories: cond-mat.other

Comments: 4 pages, 4 figures

\\

The viscosity is measured for a Fermi liquid, a dilute $^3$He-$^4$He mixture,

under extremely high magnetic field/temperature conditions ($B \leq 14.8$ T, $T

\geq 1.5$ mK). The spin splitting energy $\mu B$ is substantially greater than

the Fermi energy $k_B T_F$; as a consequence the polarization tends to unity

and s-wave quasiparticle scattering is suppressed for $T \ll T_F$. Using a

novel composite vibrating-wire viscometer an enhancement of the viscosity is

observed by a factor of more than 500 over its low-field value. Good agreement

is found between the measured viscosity and theoretical predictions based upon

a $t$-matrix formalism.

\\ ( http://arxiv.org/abs/0704.2412 , 152kb)

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arXiv:0704.2246

Date: Tue, 17 Apr 2007 22:19:57 GMT (186kb)

Title: Towards experimental entanglement connection with atomic ensembles in

the single excitation regime

Authors: J. Laurat, C.W. Chou, H. Deng, K.S. Choi, D. Felinto, H. de

Riedmatten, H.J. Kimble

Categories: quant-ph

\\

We present a protocol for performing entanglement connection between pairs of

atomic ensembles in the single excitation regime. Two pairs are prepared in an

asynchronous fashion and then connected via a Bell measurement. The resulting

state of the two remaining ensembles is mapped to photonic modes and a reduced

density matrix is then reconstructed. Our observations confirm for the first

time the creation of coherence between atomic systems that never interacted, a

first step towards entanglement connection, a critical requirement for quantum

networking and long distance quantum communications.

\\ ( http://arxiv.org/abs/0704.2246 , 186kb)

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arXiv:0704.2299

Date: Wed, 18 Apr 2007 09:29:15 GMT (244kb)

Title: One-dimensional quantum Rydberg gases in a magneto-electric trap

Authors: Michael Mayle, Bernd Hezel, Igor Lesanovsky and Peter Schmelcher

Categories: physics.atom-ph

\\

We study the quantum properties of Rydberg atoms in a magnetic

Ioffe-Pritchard trap which is superimposed by a homogeneous electric field.

Trapped Rydberg atoms can be created in long-lived electronic states exhibiting

a permanent electric dipole moment of several hundred Debye. The resulting

dipole-dipole interaction in conjunction with the radial confinement is

demonstrated to give rise to an effectively one-dimensional ultracold quantum

Rydberg gas with a macroscopic interparticle distance. We derive analytical

expressions for the electric dipole moment and the critical linear density of

Rydberg atoms.

\\ ( http://arxiv.org/abs/0704.2299 , 244kb)

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arXiv:0704.2427

Date: Wed, 18 Apr 2007 20:39:12 GMT (754kb)

Title: Stationary and non-stationary fluid flow of a Bose-Einstein condensate

through a penetrable barrier

Authors: P. Engels and C. Atherton

Categories: cond-mat.other

Comments: 4 pages, 4 figures

\\

We experimentally study the fluid flow induced by a broad, penetrable barrier

moving through an elongated dilute gaseous Bose-Einstein condensate. The

barrier is created by a laser beam swept through the condensate, and the

resulting dipole potential can be either attractive or repulsive. We examine

both cases and find regimes of stable and unstable fluid flow: At slow speeds

of the barrier, the fluid flow is stationary due to the superfluidity of the

condensate. At intermediate speeds, we observe a non-stationary regime in which

the condensate gets filled with dark solitons. At faster speeds, soliton

formation completely ceases and a remarkable absence of excitation in the

condensate is seen again.

\\ ( http://arxiv.org/abs/0704.2427 , 754kb)

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arXiv:0704.2431

Date: Wed, 18 Apr 2007 21:47:15 GMT (39kb,D)

Title: Vortex trapping in suddenly connected Bose-Josephson junctions

Authors: Parag Ghosh and Fernando Sols

Categories: cond-mat.supr-con

Comments: 4 pages, 5 figures

\\

We investigate the problem of vortex trapping in cyclically coupled

Bose-Josephson junctions. Starting with $N$ independent BECs we couple the

condensates through Josephson links and allow the system to reach a stable

circulation by adding a dissipative term in our semiclassical equations of

motion. The central question we address is what is the probability to trap a

vortex with winding number $m$. Our numerical simulations reveal that the final

distribution of winding numbers is narrower than the initial distribution of

total phases, indicating an increased probability for no-vortex configurations.

Further, the nonlinearity of the problem manifests itself in the somewhat

counter-intuitive result that it is possible to obtain a non-zero circulation

starting with zero total phase around the loop. The final width of the

distribution of winding numbers for $N$ sites scales as $\lambda N^{\alpha}$,

where $\alpha=0.47\pm 0.01$ and $\lambda <0.67$ (value predicted for the

initial distribution) indicating a shrinking of the final distribution. The

actual value of $\lambda$ is found to depend on the strength of dissipation.

\\ ( http://arxiv.org/abs/0704.2431 , 39kb)

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arXiv:0704.2439

Date: Thu, 19 Apr 2007 01:46:00 GMT (21kb)

Title: Quantum phase transitions beyond the dilute Bose gas limit

Authors: Valeri N. Kotov, D. X. Yao, A. H. Castro Neto, D. K. Campbell

Categories: cond-mat.str-el

Comments: Proceedings of SCES'07, Houston

\\

We study a Heisenberg S=1/2 ring-exchange antiferromagnet which exhibits a

quantum phase transition from a spontaneously dimerized (valence bond solid)

phase to a magnetically ordered (Neel) phase. We argue that the quantum

transition is of unconventional nature; both singlet and triplet modes of high

density condense as the transition is approached from the dimer side, signaling

restoration of lattice symmetry. These features are consistent with "deconfined

quantum criticality", of which the present model is believed to be the only

example so far.

\\ ( http://arxiv.org/abs/0704.2439 , 21kb)

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arXiv:0704.2496

Date: Thu, 19 Apr 2007 10:18:35 GMT (452kb)

Title: Phase Boundary of the Boson Mott Insulator in a Rotating Optical Lattice

Authors: R. O. Umucalilar, M. O. Oktel

Categories: cond-mat.mes-hall

Comments: 5 pages,3 figures. High resolution figures available upon request

\\

We consider the Bose-Hubbard model in a two dimensional rotating optical

lattice and investigate the consequences of the effective magnetic field

created by rotation. Using a Gutzwiller type variational wavefunction, we find

an analytical expression for the Mott insulator(MI)-Superfluid(SF) transition

boundary in terms of the maximum eigenvalue of the Hofstadter butterfly. The

dependence of phase boundary on the effective magnetic field is complex,

reflecting the self-similar properties of the single particle energy spectrum.

Finally, we argue that fractional quantum Hall phases exist close to the MI-SF

transition boundaries, including MI states with particle densities greater than

one.

\\ ( http://arxiv.org/abs/0704.2496 , 452kb)

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arXiv:0704.2280 (*cross-listing*)

Date: Wed, 18 Apr 2007 07:11:33 GMT (198kb)

Title: Full-time dynamics of modulational instability in spinor Bose--Einstein

condensates

Authors: Evgeny V. Doktorov, Vassilis M. Rothos, Yuri S. Kivshar

Categories: nlin.SI cond-mat.other

Comments: 6 pages, 2 figures, submitted to Phys. Rev. A

\\

We describe the full-time dynamics of modulational instability in spinor

Bose-Einstein condensates for the case of the integrable three-component model

associated with the matrix nonlinear Schroedinger equation. We obtain exact

homoclinic solution of this model by the dressing method generalized to the

case of higher-rank projectors. It is the homoclinic solution that is concerned

with the modulational instability development beyond the linear regime. We show

that the modulational instability demonstrates the reversal property when the

growth of the modulation amplitude changes by its exponential decay.

\\ ( http://arxiv.org/abs/0704.2280 , 198kb)

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arXiv:0704.2425

Date: Wed, 18 Apr 2007 20:29:27 GMT (88kb)

Title: Trapping and Cooling a mirror to its quantum mechanical ground state

Authors: M. Bhattacharya and P. Meystre

Categories: quant-ph

Comments: 5 pages, 1 figure

\\

We propose a technique aimed at cooling a harmonically oscillating mirror to

its quantum mechanical ground state starting from room temperature. Our method,

which involves the two-sided irradiation of the vibrating mirror inside an

optical cavity, combines several advantages over the two-mirror arrangements

being used currently. For comparable parameters the three-mirror configuration

provides a stiffer trap for the oscillating mirror. Furthermore it prevents

bistability from limiting the use of higher laser powers for mirror trapping,

and also partially does so for mirror cooling. Lastly, it improves the

isolation of the mirror from classical noise so that its dynamics are perturbed

mostly by the vacuum fluctuations of the optical fields. These improvements are

expected to bring the task of achieving ground state occupation for the mirror

closer to completion.

\\ ( http://arxiv.org/abs/0704.2425 , 88kb)

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arXiv:0704.1644 (*cross-listing*)

Date: Thu, 12 Apr 2007 18:55:27 GMT (164kb)

Title: Circulating Current States in Bilayer Fermionic and Bosonic Systems

Authors: Alexei Kolezhuk

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

Comments: 4 pages, 3 figures

\\

It is shown that fermionic polar molecules or atoms in a bilayer optical

lattice can undergo the transition to a state with circulating currents, which

spontaneously breaks the time reversal symmetry. Estimates of relevant

temperature scales are given and experimental signatures of the circulating

current phase are identified. Related phenomena in bosonic and spin systems

with ring exchange are discussed.

\\ ( http://arxiv.org/abs/0704.1644 , 164kb)

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The replacements:

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arXiv:0704.0925

replaced with revised version Fri, 13 Apr 2007 14:58:49 GMT (576kb)

Title: Spinor Dynamics in an Antiferromagnetic Spin-1 Condensate

Authors: A.T. Black, E. Gomez, L.D. Turner, S. Jung, P.D. Lett

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

Comments: 5 pages, 2 figures. Changes: added reference, minor corrections

\\ ( http://arxiv.org/abs/0704.0925 , 576kb)

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arXiv:cond-mat/0702315

replaced with revised version Mon, 16 Apr 2007 07:55:35 GMT (45kb)

Title: Interacting bosons in an optical lattice: Bose-Einstein condensates and

Mott insulator

Authors: O. Fialko, Ch. Moseley and K. Ziegler

Categories: cond-mat.stat-mech

Comments: 17 pages, 5 figures; 1 figure added, typos removed

\\ ( http://arxiv.org/abs/cond-mat/0702315 , 45kb)

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arXiv:cond-mat/0702014 (*cross-listing*)

replaced with revised version Mon, 16 Apr 2007 08:53:27 GMT (102kb)

Title: Robustness of adiabatic passage trough a quantum phase transition

Authors: Andrea Fubini, Giuseppe Falci, and Andreas Osterloh

Categories: cond-mat.stat-mech cond-mat.mes-hall quant-ph

Comments: 16 pages, 15 figures. To appear in New Journal of Physics

\\ ( http://arxiv.org/abs/cond-mat/0702014 , 102kb)

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arXiv:cond-mat/0602572

replaced with revised version Tue, 17 Apr 2007 01:24:16 GMT (177kb)

Title: Dynamical Instability of a Rotating Dipolar Bose-Einstein Condensate

Authors: R.M.W. van Bijnen, D.H.J. O'Dell, N.G. Parker and A.M. Martin

Categories: cond-mat.other

Comments: 4 pages, including 2 figures

Journal-ref: Phys. Rev. Lett. 98, 150401 (2007)

\\ ( http://arxiv.org/abs/cond-mat/0602572 , 177kb)

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arXiv:quant-ph/0702039

replaced with revised version Tue, 17 Apr 2007 18:35:56 GMT (360kb,D)

Title: Sublattice addressing and spin-dependent motion of atoms in a

double-well lattice

Authors: P. J. Lee, M. Anderlini, B. L. Brown, J. Sebby-Strabley, W. D.

Phillips, J. V. Porto

Categories: quant-ph

\\ ( http://arxiv.org/abs/quant-ph/0702039 , 360kb)

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arXiv:quant-ph/0702162

replaced with revised version Tue, 17 Apr 2007 19:54:11 GMT (524kb)

Title: Trapping and observing single atoms in the dark

Authors: T. Puppe, I. Schuster, A. Grothe, A. Kubanek, K. Murr, P.W.H. Pinkse,

and G. Rempe

Categories: quant-ph

\\ ( http://arxiv.org/abs/quant-ph/0702162 , 524kb)

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arXiv:cond-mat/0503757

replaced with revised version Wed, 18 Apr 2007 00:04:53 GMT (8kb)

Title: Casimir Friction II: Casimir effect and drag in zero temperature

superfluids

Authors: D. C. Roberts and Y. Pomeau

Categories: cond-mat.stat-mech

Comments: v4: rewrote as companion article to arXiv:0704.2194

\\ ( http://arxiv.org/abs/cond-mat/0503757 , 8kb)

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arXiv:hep-ph/0703042 (*cross-listing*)

replaced with revised version Wed, 18 Apr 2007 08:18:45 GMT (22kb)

Title: Relativistic BCS-BEC Crossover at Zero Temperature

Authors: Lianyi He and Pengfei Zhuang

Categories: hep-ph cond-mat.supr-con hep-th nucl-th

Comments: 8 pages, 3 figures. V2: typos corrected, a comment on mean field

theory added

\\ ( http://arxiv.org/abs/hep-ph/0703042 , 22kb)

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arXiv:cond-mat/0607138

replaced with revised version Thu, 19 Apr 2007 11:58:45 GMT (504kb)

Title: Color Superfluidity and "Baryon" Formation in Ultracold Fermions

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

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

Comments: 4 PRL pages, 1 figure

Journal-ref: Physical Review Letters 98, 160405 (2007)

DOI: 10.1103/PhysRevLett.98.160405

\\ ( http://arxiv.org/abs/cond-mat/0607138 , 504kb)

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arXiv:cond-mat/0607831

replaced with revised version Thu, 19 Apr 2007 14:19:51 GMT (487kb)

Title: Correlations in a BEC collision: First-principles quantum dynamics with

150 000 atoms

Authors: P. Deuar and P. D. Drummond

Categories: cond-mat.other

Comments: 4 pages, 4 figures. v2: Rewording and style changes, minor except for

rewrite of background on the positive-P representation. Original research

unchanged

Journal-ref: Phys. Rev. Lett. 98, 120402 (2007)

\\ ( http://arxiv.org/abs/cond-mat/0607831 , 487kb)

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Till next time (which hopefully will be sooner!)

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 Fri Apr 27 2007 - 15:27:55 EST

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