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

Date: Sun, 25 Jul 2010 16:20:25 +1000

Date: Sun, 25 Jul 2010 16:20:25 +1000

Dear subscribers,

This week's selection was compiled by Chris Foster, and contains 33 new

abstracts and 10 replacements.

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

\\

arXiv:1006.3673

Date: Fri, 18 Jun 2010 12:19:04 GMT (235kb)

Title: Superfluid/ferromagnet/superfluid junction and $\pi$-phase in a

superfluid Fermi gas

Authors: Takashi Kashimura, Shunji Tsuchiya, and Yoji Ohashi

Categories: cond-mat.quant-gas

Comments: 22 pages, 14 figures

\\

We investigate the possibility of superfluid/ferromagnet/superfluid

(SFS)-junction in a superfluid Fermi gas. To examine this possibility in a

simple manner, we consider an attractive Hubbard model at $T=0$ within the

mean-field theory. When a potential barrier is embedded in a superfluid Fermi

gas with population imbalance ($N_\uparrow>N_\downarrow$, where $N_\sigma$ is

the number of atoms with pseudospin $\sigma=\uparrow,\downarrow$), this barrier

is shown to be {\it magnetized} in the sense that excess $\uparrow$-spin atoms

are localized around it. The resulting superfluid Fermi gas is spatially

divided into two by this {\it ferromagnet}, so that one obtains a junction

similar to the superconductor/ferromagnet/superconductor-junction discussed in

superconductivity. Indeed, we show that the so-called $\pi$-phase, which is a

typical phenomenon in the SFS-junction, is realized, where the superfluid order

parameter changes its sign across the junction. Our results would be useful for

the study of magnetic effects on fermion superfluidity using an ultracold Fermi

gas.

\\ ( http://arxiv.org/abs/1006.3673 , 235kb)

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

\\

arXiv:1006.3687 (*cross-listing*)

Date: Fri, 18 Jun 2010 13:05:54 GMT (1319kb)

Title: Two - dimensional solitons in media with the stripe - shaped

nonlinearity modulation

Authors: Nguyen Viet Hung, Pawe\lZi\'n, Marek Trippenbach and Boris A. Malomed

Categories: nlin.PS cond-mat.quant-gas

Comments: 9 pages, 15 figures

\\

We introduce a model of media with the cubic attractive nonlinearity

concentrated along a single or double stripe in the two-dimensional (2D) plane.

The model can be realized in terms of nonlinear optics (in the spatial and

temporal domains alike) and BEC. In recent works, it was concluded that search

for stable 2D solitons in models with a spatially localized self-attractive

nonlinearity is a challenging problem. We make use of the variational

approximation (VA) and numerical methods to investigate conditions for the

existence and stability of solitons in the present setting. The result

crucially depends on the transverse shape of the stripe: while the rectangular

profile supports stable 2D solitons, its smooth Gaussian-shaped counterpart

makes all the solitons unstable. The double stripe with the rectangular profile

admit stable solitons of three distinct types: symmetric and asymmetric ones

with a single peak, and double-peak symmetric solitons. The shape and stability

of single-peak solitons of either type are accurately predicted by the VA.

Collisions between stable solitons are briefly considered too, by means of

direct simulations. Depending on the relative velocity we observe excitation,

decay or catastrophic self focusing.

\\ ( http://arxiv.org/abs/1006.3687 , 1319kb)

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

\\

arXiv:1006.3695

Date: Fri, 18 Jun 2010 14:06:18 GMT (128kb)

Title: Exact exact solutions of the Gross-Pitaevskii equation for stable vortex

modes

Authors: Lei Wu, Lu Li, Jie-Fang Zhang, Dumitru Mihalache, Boris A. Malomed,

and W. M. Liu

Categories: cond-mat.quant-gas math-ph math.MP physics.optics

Comments: 5 pages, 6 figures, to appear in Phys. Rev. A

\\

We construct exact solutions of the Gross-Pitaevskii equation for solitary

vortices, and approximate ones for fundamental solitons, in 2D models of

Bose-Einstein condensates with a spatially modulated nonlinearity of either

sign and a harmonic trapping potential. The number of vortex-soliton (VS) modes

is determined by the discrete energy spectrum of a related linear

Schr\"{o}dinger equation. The VS families in the system with the attractive and

repulsive nonlinearity are mutually complementary. \emph{% Stable} VSs with

vorticity $S\geq 2$ and those corresponding to higher-order radial states are

reported for the first time, in the case of the attraction and repulsion,

respectively.

\\ ( http://arxiv.org/abs/1006.3695 , 128kb)

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

\\

arXiv:1006.3705 (*cross-listing*)

Date: Fri, 18 Jun 2010 14:32:09 GMT (15kb)

Title: Solitary waves of Bose-Einstein condensed atoms confined in finite rings

Authors: J. Smyrnakis, M. Magiropoulos, G. M. Kavoulakis, A. D. Jackson

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

Comments: 6 pages, 2 figures

\\

Motivated by recent progress in trapping Bose-Einstein condensed atoms in

toroidal potentials, we examine solitary-wave solutions of the nonlinear

Schr\"odinger equation subject to periodic boundary conditions. When the

circumference of the ring is much larger than the size of the wave, the density

profile is well approximated by that of an infinite ring, however the density

and the velocity of propagation cannot vanish simultaneously. When the size of

the ring becomes comparable to the size of the wave, the density variation

becomes sinusoidal and the velocity of propagation saturates to a constant

value.

\\ ( http://arxiv.org/abs/1006.3705 , 15kb)

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

\\

arXiv:1006.3767

Date: Fri, 18 Jun 2010 18:12:44 GMT (360kb)

Title: Atomic population distribution in the output ports of cold-atom

interferometers with optical splitting and recombination

Authors: Ebubechukwu O. Ilo-Okeke and Alex A. Zozulya

Categories: physics.atom-ph

Comments: 25 pages, 7 figures

\\

Cold-atom interferometers with optical splitting and recombination use

off-resonant laser beams to split a cloud of Bose-Einstein condensate (BEC)

into two clouds that travel along different paths and are then recombined again

using optical beams. After the recombination, the BEC in general populates both

the cloud at rest and the moving clouds. Measuring relative number of atoms in

each of these clouds yields information about the relative phase shift

accumulated by the atoms in the two moving clouds during the interferometric

cycle. We derive the expression for the probability of finding any given number

of atoms in each of the clouds, discuss features of the probability density

distribution, analyze its dependence on the relative accumulated phase shift as

a function of the strength of the interatomic interactions, and compare our

results with experiment.

\\ ( http://arxiv.org/abs/1006.3767 , 360kb)

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

\\

arXiv:1006.3799 (*cross-listing*)

Date: Fri, 18 Jun 2010 20:17:29 GMT (3627kb,D)

Title: Single-Atom Resolved Fluorescence Imaging of an Atomic Mott Insulator

Authors: Jacob F. Sherson, Christof Weitenberg, Manuel Endres, Marc Cheneau,

Immanuel Bloch, Stefan Kuhr

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

\\

The reliable detection of single quantum particles has revolutionized the

field of quantum optics and quantum information processing. For several years,

researchers have aspired to extend such detection possibilities to larger scale

strongly correlated quantum systems, in order to record a snapshot of a quantum

fluid in which each underlying quantum particle is detected. Here we report on

fluorescence imaging of strongly interacting bosonic Mott insulators in an

optical lattice with single-atom and single-site resolution. From our images,

we fully reconstruct the atom distribution on the lattice and identify

individual excitations with high fidelity. A comparison of the radially

averaged density and variance distribution with theory provides a precise

in-situ temperature measurement from single images. We observe Mott-insulating

plateaus with near zero entropy and clearly resolve the high entropy rings

separating them although their width is of the order of only a single lattice

site. Our experiments open a new avenue for the manipulation and analysis of

strongly interacting quantum gases on a lattice, as well as for quantum

information processing with ultracold atoms. Using the high spatial resolution,

it is now possible to directly address regions of high entropy, a crucial

requirement e.g. for the implementation of novel cooling schemes for atoms on a

lattice. Furthermore, hidden order parameters of topological quantum phases

that manifest themselves as expectation values of a string of operators acting

on different sites can be detected.

\\ ( http://arxiv.org/abs/1006.3799 , 3627kb)

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

\\

arXiv:1006.3839 (*cross-listing*)

Date: Sat, 19 Jun 2010 04:33:29 GMT (188kb)

Title: Matter-wave solitons and finite-amplitude Bloch waves in optical

lattices with a spatially modulated nonlinearity

Authors: Jie-Fang Zhang, Yi-Shen Li, Jianping Meng, Lei Wu, and Boris A.

Malomed

Categories: cond-mat.quant-gas math-ph math.MP physics.optics

Comments: 9 pages, 10 figures

\\

We investigate solitons and nonlinear Bloch waves in Bose-Einstein

condensates trapped in optical lattices. By introducing specially designed

localized profiles of the spatial modulation of the attractive nonlinearity, we

construct an infinite number of exact soliton solutions in terms of the Mathieu

and elliptic functions, with the chemical potential belonging to the

semi-infinite bandgap of the optical-lattice-induced spectrum. Starting from

the exact solutions, we employ the relaxation method to construct generic

families of soliton solutions in a numerical form. The stability of the

solitons is investigated through the computation of the eigenvalues for small

perturbations, and also by direct simulations. Finally, we demonstrate a

virtually exact (in the numerical sense) composition relation between nonlinear

Bloch waves and solitons.

\\ ( http://arxiv.org/abs/1006.3839 , 188kb)

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

\\

arXiv:1006.3893

Date: Sat, 19 Jun 2010 21:22:55 GMT (256kb)

Title: The Nonlinear Dirac Equation in Bose-Einstein Condensates: Relativistic

Linear Stability Equations, Nonlinear Localized Modes, and Cherenkov

Radiation

Authors: L. H. Haddad and L. D. Carr

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

Comments: 5 pages, 2 figures

\\

Bose-Einstein condensates in a honeycomb optical lattice are described by a

nonlinear Dirac equation (NLDE) in the long wavelength, mean field limit, a

relativistic generalization of the nonlinear Schr\"odinger equation. We present

a variety of localized solutions of the NLDE: skyrmions, solitons, vortices,

and half-quantum vortices. We then derive and solve the associated relativistic

linear stability equations (RLSE). We study stability via the RLSE of localized

and uniform background solutions and present an experimentally observable

effect of our calculations in the form of Cherenkov radiation.

\\ ( http://arxiv.org/abs/1006.3893 , 256kb)

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

\\

arXiv:1006.3911

Date: Sun, 20 Jun 2010 06:16:49 GMT (797kb,D)

Title: Numerical generation of a vortex ring cascade in quantum turbulence

Authors: Robert M. Kerr

Categories: cond-mat.quant-gas nlin.PS

Comments: 22 pages 17 figures

\\

A symmetric anti-parallel quantum pair of vortices is simulated using the

three-dimensional Gross-Pitaevski equations. The initial development before

cores interact directly demonstrates the traditional vortex dynamics of

stretching, curvature and torsion in a manner consistent with a filament

calculation and simulations of the classical, ideal Euler equations. Once the

cores begin to interact, reconnection develops in the vacuum that forms between

the pair. Out of the reconnection region, vortex waves are emitted with

properties similar to waves in the local induction approximation. These waves

propagate down the initial vortex and deepen. When they deepen far enough,

secondary reconnections occur and vortex rings form. Near this time, spectra

have a $k^{-3}$ regime. As the vortex rings fully separate, the high wavenumber

spectra grow until, at the final time simulated, spectra in two directions

develop nearly -5/3 subranges. This occurs without the dissipation of energy.

Preliminary analysis of the flow of energies in spectral scale and physical

space is discussed.

\\ ( http://arxiv.org/abs/1006.3911 , 797kb)

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

\\

arXiv:1006.4014

Date: Mon, 21 Jun 2010 08:57:04 GMT (24kb)

Title: New Developments in Quantum Algorithms

Authors: Andris Ambainis

Categories: quant-ph cs.CC cs.DS

Comments: 11 pages, 1 figure, to appear as an invited survey talk at MFCS'2010

\\

In this survey, we describe two recent developments in quantum algorithms.

The first new development is a quantum algorithm for evaluating a Boolean

formula consisting of AND and OR gates of size N in time O(\sqrt{N}). This

provides quantum speedups for any problem that can be expressed via Boolean

formulas. This result can be also extended to span problems, a generalization

of Boolean formulas. This provides an optimal quantum algorithm for any Boolean

function in the black-box query model.

The second new development is a quantum algorithm for solving systems of

linear equations. In contrast with traditional algorithms that run in time

O(N^{2.37...}) where N is the size of the system, the quantum algorithm runs in

time O(\log^c N). It outputs a quantum state describing the solution of the

system.

\\ ( http://arxiv.org/abs/1006.4014 , 24kb)

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

\\

arXiv:1006.4036

Date: Mon, 21 Jun 2010 11:24:30 GMT (351kb,D)

Title: Quantum entanglement of nanocantilevers

Authors: C. Joshi, A. Hutter, F. Zimmer, M. Jonson, E. Andersson, P. Ohberg

Categories: quant-ph

Comments: 9 pages, 8 figures

\\

We propose a scheme to entangle two mechanical nanocantilevers through

indirect interactions mediated by a gas of ultra cold atoms. We envisage a

system of nanocantilevers magnetically coupled to a Bose-Einstein condensate of

atoms and focus on studying the dark states of the system. These dark states

are entangled states of the two nanocantilevers, with no coupling to the atomic

condensate. In the absence of dissipation, the degree of entanglement is found

to oscillate with time, while if dissipation is included the system is found to

relax to a time-independent statistical mixture of dark states. This opens up

the possibility of achieving long-lived entangled nanocantilever states.

\\ ( http://arxiv.org/abs/1006.4036 , 351kb)

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

\\

arXiv:1006.4049

Date: Mon, 21 Jun 2010 12:20:59 GMT (644kb)

Title: Localized and extended states in a disordered trap

Authors: Luca Pezz\'e (LCFIO), Laurent Sanchez-Palencia (LCFIO)

Categories: cond-mat.other

Comments:

\\

We study Anderson localization in a disordered potential combined with a

harmonic trap. We show that the spectrum displays both localized and extended

states, which coexist at intermediate energies. In the region of coexistence,

we find that the extended states result from confinement by the trap and are

weakly affected by the disorder. Conversely, the localized states correspond to

eigenstates of the disordered potential, which are only affected by the trap

via an inhomogeneous energy shift. These results are directly relevant to

disordered quantum gases and we propose a realistic scheme to observe the

coexistence of localized and extended states in these systems.

\\ ( http://arxiv.org/abs/1006.4049 , 644kb)

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

\\

arXiv:1006.4052

Date: Mon, 21 Jun 2010 12:24:41 GMT (1022kb)

Title: The equation of state of ultracold Bose and Fermi gases: a few examples

Authors: Sylvain Nascimb\`ene (LKB - Lhomond), Nir Navon (LKB - Lhomond),

Fr\'ed\'eric Chevy (LKB - Lhomond), C. Salomon (LKB - Lhomond)

Categories: cond-mat.quant-gas

Comments: 14 pages, 6 figures

\\

We describe a powerful method for determining the equation of state of an

ultracold gas from in situ images. The method provides a measurement of the

local pressure of an harmonically trapped gas and we give several applications

to Bose and Fermi gases. We obtain the grand-canonical equation of state of a

spin-balanced Fermi gas with resonant interactions as a function of

temperature. We compare our equation of state with an equation of state

measured by the Tokyo group, that reveals a significant difference in the

high-temperature regime. The normal phase, at low temperature, is well

described by a Landau Fermi liquid model, and we observe a clear thermodynamic

signature of the superfluid transition. In a second part we apply the same

procedure to Bose gases. From a single image of a quasi ideal Bose gas we

determine the equation of state from the classical to the condensed regime.

Finally the method is applied to a Bose gas in a 3D optical lattice in the Mott

insulator regime. Our equation of state directly reveals the Mott insulator

behavior and is suited to investigate finite-temperature effects.

\\ ( http://arxiv.org/abs/1006.4052 , 1022kb)

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

\\

arXiv:1006.4067

Date: Mon, 21 Jun 2010 13:58:39 GMT (227kb)

Title: Driven optical lattices as strong-field simulators

Authors: Stephan Arlinghaus and Martin Holthaus

Categories: cond-mat.other

Comments: 5 pages, 5 figures

Journal-ref: Phys. Rev. A 81, 063612 (2010)

DOI: 10.1103/PhysRevA.81.063612

\\

We argue that ultracold atoms in strongly shaken optical lattices can be

subjected to conditions similar to those experienced by electrons in

laser-irradiated crystalline solids, but without introducing secondary

polarization effects. As a consequence one can induce nonperturbative

multiphoton-like resonances due to the mutual penetration of ac-Stark-shifted

Bloch bands. These phenomena can be detected with a combination of currently

available laboratory techniques.

\\ ( http://arxiv.org/abs/1006.4067 , 227kb)

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

\\

arXiv:1006.4205 (*cross-listing*)

Date: Tue, 22 Jun 2010 03:57:15 GMT (74kb,D)

Title: Other incarnations of the Gross-Pitaevskii dark soliton

Authors: Indubala I Satija and Radha Balakrishnan

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

\\

We show that the dark soliton of the Gross-Pitaevskii equation (GPE) that

describes the Bose-Einstein condensate (BEC) density of a system of weakly

repulsive bosons, also describes that of a system of strongly repulsive hard

core bosons at half filling. As a consequence of this, the GPE soliton gets

related to the magnetic soliton in an easy-plane ferromagnet, where it

describes the square of the in-plane magnetization of the system. These

relationships are shown to be useful in understanding various characteristics

of solitons in these distinct many-body systems.

\\ ( http://arxiv.org/abs/1006.4205 , 74kb)

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

\\

arXiv:1006.4277

Date: Tue, 22 Jun 2010 12:36:25 GMT (282kb)

Title: Spatially-antisymmetric localization of matter wave in a bichromatic

optical lattice

Authors: Y. Cheng and S. K. Adhikari

Categories: cond-mat.quant-gas

\\

By direct numerical simulation of the time-dependent Gross-Pitaevskii

equation using the split-step Fourier spectral method we study the

double-humped localization of a cigar-shaped Bose-Einstein condensate (BEC) in

a one-dimensional bichromatic quasi-periodic optical-lattice potential, as used

in a recent experiment on the localization of a BEC [Roati et al., Nature 453,

895 (2008)]. Such states are spatially antisymmetric and are excited modes of

Anderson localization. Where possible, we have compared the numerical results

with a variational analysis. We also demonstrate the stability of the localized

double-humped BEC states under small perturbation.

\\ ( http://arxiv.org/abs/1006.4277 , 282kb)

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

\\

arXiv:1006.4315

Date: Tue, 22 Jun 2010 15:30:38 GMT (4644kb,D)

Title: Anomalous vortex ring velocities induced by thermally-excited Kelvin

waves and counterflow effects in superfluids

Authors: Giorgio Krstulovic and Marc Brachet

Categories: cond-mat.stat-mech

\\

Dynamical counterflow effects on vortex evolution under the truncated

Gross-Pitaevskii equation are investigated. Standard longitudinal mutual

friction effects are produced and a dilatation of vortex rings is obtained at

large counterflow. A strong temperature-dependent anomalous slowdown of vortex

rings is observed and attributed to the presence of thermally exited Kelvin

waves. This generic effect of finite-temperature superfluids is estimated using

energy equipartition and orders of magnitude are given for weakly interacting

Bose-Einstein condensates and superfluid $^4{\rm He}$.

\\ ( http://arxiv.org/abs/1006.4315 , 4644kb)

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

\\

arXiv:1006.4426

Date: Wed, 23 Jun 2010 06:48:49 GMT (397kb)

Title: A nonlinear quantum piston for the controlled generation of vortex rings

Authors: Natalia G. Berloff, Victor M. Perez-Garcia

Categories: cond-mat.quant-gas nlin.PS

\\

We propose a simple way to manage interactions in Bose-Einstein condensates

to generate vortex rings in a highly controllable way.

The vortex rings are generated under the action of a quantum analogue of a

classical piston pushing the condensed atoms through a small aperture.

\\ ( http://arxiv.org/abs/1006.4426 , 397kb)

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

\\

arXiv:1006.4429

Date: Wed, 23 Jun 2010 06:54:22 GMT (741kb)

Title: Quantitative study of 3D and 2D strong localization of matter waves by

atomic scatterers

Authors: Mauro Antezza (LKB - Lhomond), Yvan Castin (LKB - Lhomond), David

Hutchinson

Categories: cond-mat.quant-gas

Comments:

\\

We study the strong localization of atomic matter waves in a disordered

potential created by atoms pinned at the nodes of a lattice, for both 3D and 2D

systems. The localization length of the matter wave, the density of localized

states, and the occurrence of energy mobility edges (for the 3D system), are

numerically investigated as a function of the effective scattering length

between the atomic matter wave and the pinned atoms. Both positive and negative

matter wave energies are explored. Interesting features of the density of

states are discovered at negative energies, where maximums in the density of

bound states for the system can be interpreted in terms of bound states of a

matter wave atom with a few pinned atomic scatterers. In 3D we found evidences

of up to three mobility edges, one at positive energies, and two at negative

energies, the latter corresponding to transitions between extended and

localized bound states. In 2D, no mobility edge is found, and a rapid

exponential-like increase of the localization length is observed at high

energy.

\\ ( http://arxiv.org/abs/1006.4429 , 741kb)

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

\\

arXiv:1006.4450

Date: Wed, 23 Jun 2010 09:19:15 GMT (56kb)

Title: Two-superfluid Model of Two-component Bose-Einstein Condensates; First

Sound and Second Sound

Authors: Shungo. Ishino, Hiromitsu Takeuchi, Makoto. Tsubota

Categories: cond-mat.quant-gas

Comments: 6 pages, 1 figures, submitted to Journal of Low Temperature Physics

\\

Superfluid $^4$He at a finite temperature is described by the two-fluid model

with the normal fluid component and the superfluid component.We formulate the

two-fluid model for two-component BECs, namely two-superfluid model, starting

from the coupled Gross-Pitaevskii equations.The two-superfluid model well

corresponds to the two-fluid model in superfluid $^4$He.In a special condition,

the two sound modes in the two-superfluid model behave like first and second

sounds in the two-fluid model of superfluid $^4$He.

\\ ( http://arxiv.org/abs/1006.4450 , 56kb)

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

\\

arXiv:1006.4488

Date: Wed, 23 Jun 2010 11:57:56 GMT (1334kb)

Title: Counterflow Quantum Turbulence and the Instability in Two-component

Bose-Einstein Condensates

Authors: Shungo Ishino, Hiromitsu Takeuchi, Makoto Tsubota

Categories: cond-mat.quant-gas

Comments: 7 pages, 5 figures, submitted to Journal of Low Temperature Physics

\\

We theoretically study the nonlinear dynamics of the instability of

counter-superflow in two miscible Bose-Einstein condensates. The condensates

become unstable when the relative velocity exceeds a critical value, which is

called counter-superflow instability. We reveal that the counter-superflow

instability can lead to quantum turbulence by numerically solving the coupled

Gross-Pitaevskii equations. The modes amplified by the instability grow into

solitons and decay into quantized vortices.Eventually, the vortices become

tangled and quantum turbulence of two superfluids. We show that this process

may occur in experiments by investigating the dynamics in a 2D trapped system.

\\ ( http://arxiv.org/abs/1006.4488 , 1334kb)

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

\\

arXiv:1006.4526

Date: Wed, 23 Jun 2010 14:14:54 GMT (308kb,D)

Title: Laser cooling with a single laser beam and a planar diffractor

Authors: Matthieu Vangeleyn, Paul F. Griffin, Erling Riis and Aidan S. Arnold

Categories: physics.atom-ph

Comments: 3 pages, 4 figures

\\

A planar triplet of diffraction gratings is used to transform a single laser

beam into a four-beam tetrahedral magneto-optical trap. This `flat' pyramid

diffractor geometry is ideal for future microfabrication. We demonstrate the

technique by trapping and subsequently sub-Doppler cooling 87Rb atoms to

30microKelvin.

\\ ( http://arxiv.org/abs/1006.4526 , 308kb)

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

\\

arXiv:1006.4532 (*cross-listing*)

Date: Wed, 23 Jun 2010 14:39:33 GMT (1386kb,D)

Title: Optimized magnetic lattices for ultracold atomic ensembles

Authors: Roman Schmied, Dietrich Leibfried, Robert J. C. Spreeuw, and Shannon

Whitlock

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

Comments: 11 pages, 5 figures

\\

We introduce a general method for designing tailored lattices of magnetic

microtraps for ultracold atoms, on the basis of patterned permanently

magnetized films. A fast numerical algorithm is used to automatically generate

patterns which provide optimal atom confinement while respecting desired

lattice symmetries and trap parameters. The algorithm can produce finite and

infinite lattices of any plane symmetry; we focus specifically on square and

triangular lattices which are of interest to future experiments. Typical trap

parameters are discussed as well as the impact of realistic imperfections such

as finite lithographic resolution and magnetic inhomogeneity. The presented

designer lattices open new avenues for quantum simulation and quantum

information processing with ultracold atoms on atom chips.

\\ ( http://arxiv.org/abs/1006.4532 , 1386kb)

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

\\

arXiv:1006.4579

Date: Wed, 23 Jun 2010 16:07:28 GMT (61kb)

Title: Dynamics of a quantum quench in an ultra-cold atomic BCS superfluid

Authors: Chih-Chun Chien and Bogdan Damski

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

Comments: 4 pages, 3 figures

Report-no: LAUR 10-04106

\\

We study dynamics of an ultra-cold atomic BCS superfluid driven towards the

BCS superfluid-Fermi liquid quantum critical point by a gradual decrease of the

pairing interaction. We analyze how the BCS superfluid falls out of equilibrium

and show that the non-equilibrium gap and Cooper pair size reflect critical

properties of the transition. We observe three stages of evolution: adiabatic

where the Cooper pair size is inversely proportional to the equilibrium gap,

weakly non-equilibrium where it is inversely proportional to the

non-equilibrium gap, and strongly non-equilibrium where it decouples from both

equilibrium and non-equilibrium gap. These phenomena should stimulate future

experimental characterization of non-equilibrium ultra-cold atomic BCS

superfluids.

\\ ( http://arxiv.org/abs/1006.4579 , 61kb)

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

\\

arXiv:1006.4619

Date: Wed, 23 Jun 2010 19:18:58 GMT (30kb)

Title: Origin of nonlinear optical processes in matter-wave superradiance

Authors: L. Deng and E.W. Hagley

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

\\

We study a highly efficient, matter-wave amplification mechanism in a

longitudinally-excited, Bose-Einstein condensate and reveal a very large

enhancement due to nonlinear gain from a sixmatter- optical, wave-mixing

process involving four photons. Under suitable conditions this

opticallydegenerate, four-photon process can be stronger than the usual

two-photon inelastic light scattering mechanism, leading to nonlinear growth of

the observed matter-wave scattering independent of any enhancement from bosonic

stimulation. Our theoretical framework can be extended to encompass even

higher-order, nonlinear superradiant processes that result in higher-order

momentum transfer.

\\ ( http://arxiv.org/abs/1006.4619 , 30kb)

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

\\

arXiv:1006.4666

Date: Thu, 24 Jun 2010 00:51:31 GMT (2872kb)

Title: Markovian Master Equations: A Critical Study

Authors: \'Angel Rivas, A. Douglas K. Plato, Susana F. Huelga and Martin B.

Plenio

Categories: quant-ph

Comments: 40 pages, 14 figures

\\

We derive Markovian master equations of single and interacting harmonic

systems in different scenarios, including strong internal coupling. By

comparing the dynamics resulting from the corresponding Markovian master

equations with exact numerical simulations of the evolution of the global

system, we precisely delimit their validity regimes and assess the robustness

of the assumptions usually made in the process of deriving the reduced

dynamics. The proposed method is sufficiently general to suggest that the

conclusions made here are widely applicable to a large class of settings

involving interacting chains subject to a weak interaction with an environment.

\\ ( http://arxiv.org/abs/1006.4666 , 2872kb)

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

\\

arXiv:1006.4674 (*cross-listing*)

Date: Thu, 24 Jun 2010 02:30:44 GMT (152kb,D)

Title: Spin gradient demagnetization cooling of ultracold atoms

Authors: Patrick Medley, David M. Weld, Hirokazu Miyake, David E. Pritchard,

and Wolfgang Ketterle

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

Comments: 12 pages, 4 figures

\\

Attainment of lower temperatures has frequently enabled discoveries of new

physical phenomena, from superconductivity to Bose-Einstein condensation. Here

we describe and demonstrate a cooling method, spin gradient demagnetization,

which has several novel features: It operates directly in the spin degree of

freedom, it can be applied to atoms in an optical lattice, and it is able to

reach positive and negative spin temperatures of $\pm$50 picokelvin, the lowest

temperatures which have been achieved in any system. The cooling method

consists of applying a time-varying magnetic field gradient to a spin mixture

of ultracold atoms. The spin system can also be used to cool other degrees of

freedom, and we have used this coupling to reduce the temperature of an

apparently equilibrated sample of rubidium atoms in an optical lattice to 350

picokelvin. These results open a realistic path to the observation of magnetic

quantum phase transitions in optical lattices.

\\ ( http://arxiv.org/abs/1006.4674 , 152kb)

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

\\

arXiv:1006.4705

Date: Thu, 24 Jun 2010 07:47:03 GMT (95kb)

Title: Diamagnetism versus Paramagnetism in charged spin-1 Bose gases

Authors: Xiaoling Jian, Jihong Qin, and Qiang Gu

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

Comments: 6 pages, 5 figures

\\

It has been suggested that either diamagnetism or paramagnetism of Bose

gases, due to the charge or spin degrees of freedom respectively, appears

solely to be extraordinarily strong. We investigate magnetic properties of

charged spin-1 Bose gases in external magnetic field, focusing on the

competition between the diamagnetism and paramagnetism, using the Lande-factor

$g$ of particles to evaluate the strength of paramagnetic effect. We propose

that a gas with $g<{1/\sqrt{8}}$ exhibits diamagnetism at all temperatures,

while a gas with $g>{1/2}$ always exhibits paramagnetism. Moreover, a gas with

the Lande-factor in between shows a shift from paramagnetism to diamagnetism as

the temperature decreases. The paramagnetic and diamagnetic contributions to

the total magnetization density are also calculated in order to demonstrate

some details of the competition.

\\ ( http://arxiv.org/abs/1006.4705 , 95kb)

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

\\

arXiv:1006.4720

Date: Thu, 24 Jun 2010 08:42:39 GMT (18kb)

Title: Four-body Efimov effect

Authors: Yvan Castin (LKB - Lhomond), Christophe Mora (LPA), Ludovic

Pricoupenko (LPTMC)

Categories: cond-mat.quant-gas

Comments: 4 pages, 2 figures

\\

We study three same spin state fermions of mass M interacting with a

distinguishable particle of mass m in the unitary limit where the interaction

has a zero range and an infinite s-wave scattering length. We predict an

interval of mass ratio 13.384 < M/m < 13.607 where there exists a purely

four-body Efimov effect, leading to the occurrence of weakly bound tetramers

without Efimov trimers.

\\ ( http://arxiv.org/abs/1006.4720 , 18kb)

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

\\

arXiv:1006.4734

Date: Thu, 24 Jun 2010 10:19:26 GMT (2237kb)

Title: Groundstate and Collective Modes of a Spin-Polarized Dipolar

Bose-Einstein Condensate in a Harmonic Trap

Authors: I. Sapina, T. Dahm and N. Schopohl

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

\\

We report new results for the Thomas-Fermi groundstate and the quadrupolar

modes of density oscillations of a spin- polarized dipolar interacting

Bose-Einstein condensate for the case when the external magnetic field is not

orientated parallel to a principal axis of a harmonic anisotropic trap.

\\ ( http://arxiv.org/abs/1006.4734 , 2237kb)

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

\\

arXiv:1006.4772

Date: Thu, 24 Jun 2010 12:24:54 GMT (1526kb)

Title: Quantum noise in optical interferometers

Authors: Volodymyr G. Voronov and Michael Weyrauch

Categories: quant-ph gr-qc

Comments: 15 pages, 7 figures

Journal-ref: Phys. Rev. A 81, 053816 (2010)

DOI: 10.1103/PhysRevA.81.053816

\\

We study the photon counting noise in optical interferometers used for

gravitational wave detection. In order to reduce quantum noise a squeezed

vacuum is injected into the usually unused input port. It is investigated under

which conditions the gravitational wave signal may be amplified without

increasing counting noise concurrently. Such a possibility was suggested as a

consequence of the entanglement of the two output ports of a beam splitter. We

find that amplification without concurrent increase of noise is not possible

for reasonable squeezing parameters. Photon distributions for various beam

splitter angles and squeezing parameters are calculated.

\\ ( http://arxiv.org/abs/1006.4772 , 1526kb)

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

\\

arXiv:1006.4798

Date: Thu, 24 Jun 2010 14:18:09 GMT (2440kb,D)

Title: Variational calculations on multilayer stacks of dipolar Bose-Einstein

condensates

Authors: Andrej Junginger, J\"org Main, G\"unter Wunner

Categories: cond-mat.quant-gas

Comments: 9 pages, 9 figures

\\

We investigate a multilayer stack of dipolar Bose-Einstein condensates in

terms of a simple Gaussian variational ansatz and demonstrate that this

arrangement is characterized by the existence several stationary states. Using

a Hamiltonian picture we show that in an excited stack there is a coupled

motion of the individual condensates by which they exchange energy. We find

that for high excitations the interaction between the single condensates can

induce the collapse of one of them. We furthermore demonstrate that one

collapse in the stack can force other collapses, too. We discuss the

possibility of experimentally observing the coupled motion and the relevance of

the variational results found to full numerical investigations.

\\ ( http://arxiv.org/abs/1006.4798 , 2440kb)

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

\\

arXiv:1006.4817

Date: Thu, 24 Jun 2010 15:39:55 GMT (13kb)

Title: Does one need to consider superconductivity as Bose-Einstein

condensation?

Authors: B.V.Vasiliev

Categories: cond-mat.supr-con

\\

It is shown that the temperature dependence of the value of energy gap in

superconductors can be classified as the order-disorder transition with its

characteristic features. The obtained relationship between the critical

temperature and the critical magnetic field of the condensate of electrically

charged particles is in accordance with measurement data of superconductors.

\\ ( http://arxiv.org/abs/1006.4817 , 13kb)

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

The replacements:

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

\\

arXiv:1005.2203

replaced with revised version Fri, 18 Jun 2010 00:35:37 GMT (53kb)

Title: Bose-Einstein Condensates on slightly asymmetric double-well potentials

Authors: B. Julia-Diaz, J. Martorell, A. Polls

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

Comments: minor labeling corrections, 6 pages, 4 figures

Journal-ref: Phys. Rev. A 81, 063625 (2010)

DOI: 10.1103/PhysRevA.81.063625

\\ ( http://arxiv.org/abs/1005.2203 , 53kb)

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

\\

arXiv:0912.5275

replaced with revised version Fri, 18 Jun 2010 09:53:46 GMT (343kb)

Title: Collective modes as a probe of imbalanced Fermi gases

Authors: Jonathan M. Edge, N. R. Cooper

Categories: cond-mat.quant-gas

Comments: 11 pages, 9 figures

Journal-ref: Phys. Rev. A 81, 063606 (2010) [11 pages]

DOI: 10.1103/PhysRevA.81.063606

\\ ( http://arxiv.org/abs/0912.5275 , 343kb)

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

\\

arXiv:0907.1757

replaced with revised version Sun, 20 Jun 2010 09:31:03 GMT (10kb)

Title: Free Expansion of a Weakly-interacting Dipolar Fermi Gas

Authors: Takushi Nishimura and Tomoyuki Maruyama

Categories: cond-mat.quant-gas

\\ ( http://arxiv.org/abs/0907.1757 , 10kb)

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

\\

arXiv:1006.0734

replaced with revised version Mon, 21 Jun 2010 14:41:39 GMT (76kb)

Title: Quantum phase estimation without a priori knowledge-losses imply shot

noise scaling

Authors: Jan Kolodynski and Rafal Demkowicz-Dobrzanski

Categories: quant-ph

Comments: 4 pages, 2 figures

\\ ( http://arxiv.org/abs/1006.0734 , 76kb)

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

\\

arXiv:1003.5873

replaced with revised version Mon, 21 Jun 2010 21:08:28 GMT (23kb)

Title: Bound States and Universality in Layers of Cold Polar Molecules

Authors: J. R. Armstrong, N. T. Zinner, D. V. Fedorov, A. S. Jensen

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

Comments: 6 pages, 5 figures. Revised version to be published

\\ ( http://arxiv.org/abs/1003.5873 , 23kb)

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

\\

arXiv:1003.1435

replaced with revised version Tue, 22 Jun 2010 00:57:20 GMT (136kb)

Title: Effective Simulation of Quantum Entanglement Based on Classical Fields

Modulated with Pseudorandom Phase Sequences

Authors: Jian Fu, Shuo Sun, Yingying Xu and Hongtao Dong

Categories: quant-ph

Comments: 5 pages, 2 figures, a minor error corrected

\\ ( http://arxiv.org/abs/1003.1435 , 136kb)

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

\\

arXiv:1006.3038

replaced with revised version Tue, 22 Jun 2010 14:25:23 GMT (161kb)

Title: Creation of NOON states by double Fock-state/Bose-Einstein condensates

Authors: W. J. Mullin \and F. Lalo\"{e}

Categories: quant-ph

Comments: 8 pages 5 figures

\\ ( http://arxiv.org/abs/1006.3038 , 161kb)

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

\\

arXiv:1006.2324

replaced with revised version Wed, 23 Jun 2010 08:08:02 GMT (243kb)

Title: Self-localization of a small number of Bose particles in a superfluid

Fermi system

Authors: Katarzyna Targonska and Krzysztof Sacha

Categories: cond-mat.quant-gas

Comments: 7 pages, 7 fiqures, improved version

\\ ( http://arxiv.org/abs/1006.2324 , 243kb)

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

\\

arXiv:0909.0565

replaced with revised version Thu, 24 Jun 2010 10:05:54 GMT (6936kb)

Title: Spontaneous Magnetic Ordering in a Ferromagnetic Spinor Dipolar

Bose-Einstein Condensate

Authors: Yuki Kawaguchi, Hiroki Saito, Kazue Kudo, and Masahito Ueda

Categories: cond-mat.quant-gas

Comments: Extended version of the previous one; 19 pages, 18 figures

\\ ( http://arxiv.org/abs/0909.0565 , 6936kb)

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

\\

arXiv:1005.1158

replaced with revised version Thu, 24 Jun 2010 14:59:54 GMT (26kb)

Title: Temperature and coupling dependence of the universal contact intensity

for an ultracold Fermi gas

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

Categories: cond-mat.quant-gas

Comments: 5 pages, 5 figures

\\ ( http://arxiv.org/abs/1005.1158 , 26kb)

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

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 Wed Sep 01 2010 - 11:01:37 EST

*
This archive was generated by hypermail 2.2.0
: Wed Sep 01 2010 - 11:01:48 EST
*