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

Date: Mon, 18 Oct 2010 22:32:45 +1000

Date: Mon, 18 Oct 2010 22:32:45 +1000

Dear subscribers,

This week's selection was compiled by Mike Garrett, and contains 34 new

abstracts and 18 replacements.

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arXiv:0905.3263 (*cross-listing*)

Date: Wed, 20 May 2009 09:58:07 GMT (280kb,D)

Title: Energy cascades and spectra in turbulent Bose-Einstein condensates

Authors: Davide Proment, Sergey Nazarenko, Miguel Onorato

Categories: nlin.CD cond-mat.other physics.flu-dyn

Comments: 10 pages, 5 figures

DOI: 10.1103/PhysRevA.80.051603

\\

We present a numerical study of turbulence in Bose-Einstein condensates

within the 3D Gross-Pitaevskii equation. We concentrate on the direct energy

cascade in forced-dissipated systems. We show that behavior of the system is

very sensitive to the properties of the model at the scales greater than the

forcing scale, and we identify three different universal regimes: (1) a

non-stationary regime with condensation and transition from a four-wave to a

three-wave interaction process when the largest scales are not dissipated, (2)

a steady weak wave turbulence regime when largest scales are dissipated with a

friction-type dissipation, (3) a state with a scale-by-scale balance of the

linear and the nonlinear timescales when the large-scale dissipation is a

hypo-viscosity.

\\ ( http://arxiv.org/abs/0905.3263 , 280kb)

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arXiv:1007.5331 (*cross-listing*)

Date: Thu, 29 Jul 2010 20:38:25 GMT (1502kb)

Title: Nonequilibrium dynamics of closed interacting quantum systems

Authors: Anatoli Polkovnikov, Krishnendu Sengupta, Alessandro Silva, Mukund

Vengalattore

Categories: cond-mat.stat-mech cond-mat.quant-gas hep-th quant-ph

Comments: 22 pages, 2 Figures, Colloquium, submitted to RMP

\\

This colloquium gives an overview of recent theoretical and experimental

progress in the area of nonequilibrium dynamics of isolated quantum systems. We

particularly focus on quantum quenches: the temporal evolution following a

sudden or slow change of the coupling constants of the system Hamiltonian. We

discuss several aspects of the slow dynamics in driven systems and emphasize

the universality of such dynamics in gapless systems with specific focus on

dynamics near continuous quantum phase transitions. We also review recent

progress on understanding thermalization in closed systems through the

eigenstate thermalization hypothesis and discuss relaxation in integrable

systems. Finally we overview key experiments probing quantum dynamics in cold

atom systems and put them in the context of our current theoretical

understanding.

\\ ( http://arxiv.org/abs/1007.5331 , 1502kb)

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arXiv:1007.5380

Date: Fri, 30 Jul 2010 06:50:20 GMT (752kb)

Title: Phase-space description of the magneto-optical trap

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

(PhLAM)

Categories: physics.atom-ph

Comments:

\\

An exhaustive kinetic model for the atoms in a 1D Magneto-Optical Trap is

derived, without any approximations. It is shown that the atomic density is

described by a Vlasov-Fokker-Planck equation, coupled with two simple

differential equations describing the trap beam propagation. The analogy of

such a system with plasmas is discussed. This set of equations is then

simplified through some approximations, and it is shown that corrective terms

have to be added to the models usually used in this context.

\\ ( http://arxiv.org/abs/1007.5380 , 752kb)

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arXiv:1007.5453

Date: Fri, 30 Jul 2010 13:58:09 GMT (61kb)

Title: Energy relaxation in the Gross-Pitaevskii equation

Authors: Michiel Wouters and Vincenzo Savona

Categories: cond-mat.quant-gas

Comments: 4 pages, 3 figures

\\

We introduce a dissipation term in the Gross-Pitaevskii equation that

describes the stimulated relaxation of condensed bosons due to scattering with

a different type of particles. This situation applies to Bose-Einstein

condensates of quasi-particles in the solid state, such as magnons and

excitons. Our model is compatible with the phenomenology of superfluidity:

supercurrents are stable up to a critical speed and decay when they are faster.

\\ ( http://arxiv.org/abs/1007.5453 , 61kb)

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arXiv:1007.5457

Date: Fri, 30 Jul 2010 14:20:40 GMT (64kb)

Title: Canted Antiferromagnetic Order of Imbalanced Fermi-Fermi mixtures in

Optical Lattices by Dynamical Mean-Field Theory

Authors: Michiel Snoek and Irakli Titvinidze and Walter Hofstetter

Categories: cond-mat.quant-gas

Comments: 6 pages, 5 figures

\\

We investigate antiferromagnetic order of repulsively interacting fermionic

atoms in an optical lattice by means of Dynamical Mean-Field Theory (DMFT).

Special attention is paid to the case of an imbalanced mixture, in which case

the antiferromagnetism is directed perpendicular to the ferromagnetic

polarization and canted. We take into account the presence of an underlying

harmonic trap, both in a local density approximation and by performing full

Real-Space DMFT calculations. For the moderately strong interactions considered

here, no Stoner instability towards a ferromagnetic phase is found. Phase

separation is only observed for strong imbalance and sufficiently large

repulsion.

\\ ( http://arxiv.org/abs/1007.5457 , 64kb)

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arXiv:1007.5486

Date: Fri, 30 Jul 2010 16:15:53 GMT (1058kb)

Title: Circular Dichroism of RbHe and RbN$_2$ Molecules

Authors: B. Lancor, E. Babcock, R. Wyllie, and T. G. Walker

Categories: physics.atom-ph

\\

We present measurements of the circular dichroism of optically pumped Rb

vapor near the D1 resonance line. Collisions with the buffer gases $^3$He and

N$_2$ reduce the transparency of the vapor, even when fully polarized. We use

two methods to measure this effect, show that the He results can be understood

from RbHe potential curves, and show how this effect conspires with the

spectral profile of the optical pumping light to increase the laser power

demands for optical pumping of very optically thick samples.

\\ ( http://arxiv.org/abs/1007.5486 , 1058kb)

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arXiv:1008.0007 (*cross-listing*)

Date: Fri, 30 Jul 2010 20:13:54 GMT (65kb)

Title: Viscosity and scale invariance in the unitary Fermi gas

Authors: Tilman Enss, Rudolf Haussmann, Wilhelm Zwerger

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

Comments: 19 pages, 9 figures

\\

We compute the shear viscosity of the unitary Fermi gas above the superfluid

transition temperature, using a diagrammatic technique that starts from the

exact Kubo formula. The formalism obeys a Ward identity associated with scale

invariance which guarantees that the bulk viscosity vanishes identically. For

the shear viscosity, vertex corrections and the associated Aslamazov-Larkin

contributions are shown to be crucial to reproduce the full Boltzmann equation

result in the high-temperature, low fugacity limit. The frequency dependent

shear viscosity $\eta(\omega)$ exhibits a Drude-like transport peak and a

power-law tail at large frequencies that is proportional to the Tan contact.

The weight in the transport peak is given by the equilibrium energy density,

consistent with a sum rule that has recently been derived by Taylor and

Randeria. Near the superfluid transition, the peak width is of the order $0.5\,

T_F$, thus invalidating a quasiparticle description. The ratio $\eta/s$ between

the static shear viscosity and the entropy density exhibits a minimum near the

superfluid transition temperature whose value is larger than the string theory

bound $\hbar/(4\pi k_B)$ by a factor of about seven.

\\ ( http://arxiv.org/abs/1008.0007 , 65kb)

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arXiv:1008.0036

Date: Sat, 31 Jul 2010 00:38:43 GMT (851kb)

Title: Superfluid state in the periodic Anderson model with attractive

interactions

Authors: Akihisa Koga and Philipp Werner

Categories: cond-mat.quant-gas

Comments: 16 pages, 8 figures

\\

We investigate the periodic Anderson model with attractive interactions by

means of dynamical mean-field theory (DMFT). Using a continuous-time quantum

Monte Carlo impurity solver, we study the competition between the superfluid

state and the paramagnetic Kondo insulating state, and determine the phase

diagram. At the chemical potential-induced phase transition from the Kondo

insulating state to the superfluid state, a low-energy peak characteristic of

the superfluid state appears inside the hybridization gap. We also address the

effect of the confining potential in optical lattice systems by means of

real-space DMFT calculations.

\\ ( http://arxiv.org/abs/1008.0036 , 851kb)

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arXiv:1008.0059

Date: Sat, 31 Jul 2010 07:15:36 GMT (186kb)

Title: Connection between rotation and miscibility in a two-component

Bose-Einstein condensate

Authors: Takayuki Shimodaira, Tetsuo Kishimoto, Hiroki Saito

Categories: cond-mat.quant-gas

Comments: 6 pages, 7 figures

Journal-ref: Phys. Rev. A 82, 013647 (2010)

\\

A two-component Bose-Einstein condensate rotating in a toroidal trap is

investigated. The topological constraint depends on the density distribution of

each component along the circumference of the torus, and therefore the

quantization condition on the circulation can be controlled by changing the

miscibility using the Feshbach resonance. We find that the system exhibits a

variety of dynamics depending on the initial angular momentum when the

miscibility is changed.

\\ ( http://arxiv.org/abs/1008.0059 , 186kb)

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arXiv:1008.0084

Date: Sat, 31 Jul 2010 11:56:05 GMT (153kb)

Title: Correlation studies in a spin imbalanced fermionic superfluid in

presence of a harmonic trap

Authors: Poulumi Dey, Saurabh Basu and Ram Kishore

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

Comments: 9 pages, 9 figures, 1 table

\\

We investigate different physical properties of a spin imbalanced fermionic

superfluid described by an attractive Hubbard model in presence of a harmonic

trap. To characterize the ground state of such a system, we compute various

correlation functions, such as pairing, density and current correlations To

underscore the effect of the trap, we compute these quantities as a function of

strength of the trapping potential. A distinguishing feature of a superfluid

state with population imbalance, is the appearance of a phase with spatially

modulating gap function, called the Fulde- Ferrell-Larkin-Ovchinnikov (FFLO)

phase which is present for both with and without trap. Trapping effects induce

lowering of particle density and yields an empty system in the limit of large

trapping depths.

\\ ( http://arxiv.org/abs/1008.0084 , 153kb)

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arXiv:1008.0096 (*cross-listing*)

Date: Sat, 31 Jul 2010 14:39:39 GMT (3133kb,D)

Title: Sustained turbulence in the three-dimensional Gross-Pitaevskii model

Authors: Davide Proment, Sergey Nazarenko, Miguel Onorato

Categories: nlin.CD cond-mat.other

Comments: 37 pages, 22 figures

\\

We study the 3D forced-dissipated Gross-Pitaevskii equation. We force at

relatively low wave numbers, expecting to observe a direct energy cascade and a

consequent power-law spectrum of the form $k^{-\alpha}$. Our numerical results

show that the exponent $\alpha$ strongly depends on how the inverse particle

cascade is attenuated at $k$'s lower than the forcing wave number. If the

inverse cascade is arrested by a friction at low $k$'s, we observe an exponent

which is in good agreement with the weak wave turbulence prediction $k^{-1}$.

For a hypo-viscosity, a $k^{-2}$ spectrum is observed which we explain using a

critical balance argument. In simulations without any low-$k$ dissipation, a

condensate at $k=0$ is growing and the system goes through a strongly-turbulent

transition from a four-wave to a three-wave weak turbulence acoustic regime

with $k^{-3/2}$ Zakharov-Sagdeev spectrum. In this regime, we also observe a

spectrum for the incompressible kinetic energy which formally resembles the

Kolmogorov $k^{-5/3}$, but whose correct explanation should be in terms of the

Kelvin wave turbulence. The probability density functions for the velocities

and the densities are also discussed.

\\ ( http://arxiv.org/abs/1008.0096 , 3133kb)

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arXiv:1008.0210

Date: Sun, 1 Aug 2010 23:06:11 GMT (181kb)

Title: Hall viscosity, orbital spin, and geometry: paired superfluids and

quantum Hall systems

Authors: N. Read, E.H. Rezayi

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

Comments: 26 pages, 10 figures

\\

The Hall viscosity, a non-dissipative transport coefficient analogous to Hall

conductivity, is considered for quantum fluids in gapped or topological phases.

The relation to mean orbital spin per particle discovered in previous work by

one of us (NR) is elucidated with the help of examples, using the geometry of

shear transformations and rotations. For non-interacting particles in a

magnetic field, there are several ways to derive the result (even at non-zero

temperature), including standard linear response theory. Arguments for the

quantization, and the robustness of Hall viscosity to small changes in the

Hamiltonian that preserve rotational invariance, are given. Numerical

calculations of adiabatic transport are performed to check the predictions for

quantum Hall systems, with excellent agreement for trial states. The

coefficient of k^4 in the static structure factor is also considered, and shown

to be exactly related to the orbital spin and robust to perturbations in

rotation invariant systems also.

\\ ( http://arxiv.org/abs/1008.0210 , 181kb)

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arXiv:1008.0217

Date: Mon, 2 Aug 2010 02:34:12 GMT (186kb)

Title: Computational Theory of a splitting BEC using a Generalized Wannier

basis I: Theory and Statics

Authors: Douglas K. Faust and William P. Reinhardt

Categories: cond-mat.quant-gas

Comments: 25 pages, 7 figures

\\

We present a novel and tractable method using what may be considered to be a

generalized Wannier basis to describe the splitting of a large number of

indistinguishable bosons trapped in a single potential well which is then

deformed into two wells during a finite time. This method incorporates

successful features of previous theoretical and computational assays into the

splitting problem, including mean field effects, and with access to the trap

parameters and particle numbers relevant to recent experiments. At all times we

are able to discern between a two-mode state and a state which is described

sufficiently by mean field theory and, further give a criterion and technique

for matching the two-mode theory to the zero-barrier state. We compare the

basis used in this model to the de-localized basis functions underlying

different models used in recent work. We show that only the generalized Wannier

basis displays the level crossing and emergence of two complex order parameters

with overall $U(1) \oplus U(1)$ symmetry as expected from a large$-N$ analog of

the superfluid to Mott insulator transition. Finally, we identify a universal

structure, independent of $N$ in this phase transition and discuss its

consequences for realizing true two-mode physics with a BEC which trends

towards the thermodynamic limit.

\\ ( http://arxiv.org/abs/1008.0217 , 186kb)

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arXiv:1008.0240

Date: Mon, 2 Aug 2010 07:14:54 GMT (15kb)

Title: The p=0 condensate is a myth

Authors: Yatendra S. Jain

Categories: cond-mat.quant-gas

Comments: 9 pages including 1 figure

\\

Analyzing some of the basic aspects of the dynamics of two bosons

(interacting through a central force) and their importance in determining the

ground state of a system like liquid $^4He$, it is unequivocally concluded that

our conventional belief in the existence $p=0$ condensate in the superfluid

state of such systems [including the state of Bose Einstein condensate (BEC) of

trapped dilute gases] is a myth.

\\ ( http://arxiv.org/abs/1008.0240 , 15kb)

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arXiv:1008.0314

Date: Mon, 2 Aug 2010 14:37:40 GMT (218kb,D)

Title: Reproducible mesoscopic superpositions of Bose-Einstein condensates and

mean-field chaos

Authors: Bettina Gertjerenken, Stephan Arlinghaus, Niklas Teichmann, Christoph

Weiss

Categories: cond-mat.quant-gas

Comments: 7 pages, 7 png figures, accepted for publication in Phys. Rev. A

\\

In a parameter regime for which the mean-field (Gross-Pitaevskii) dynamics

becomes chaotic, mesoscopic quantum superpositions in phase space can occur in

a double-well potential which is shaken periodically. For experimentally

realistic initial states like the ground state of some 100 atoms, the emergence

of mesoscopic quantum superpositions in phase space is investigated

numerically. It is shown to be reproducible even if the initial conditions

slightly change. While the final state is not a perfect superposition of two

distinct phase-states, the superposition is reached an order of magnitude

faster than in the case of the collapse and revival phenomenon. Furthermore, a

generator of entanglement is identified.

\\ ( http://arxiv.org/abs/1008.0314 , 218kb)

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arXiv:1008.0361 (*cross-listing*)

Date: Mon, 2 Aug 2010 17:58:36 GMT (7200kb,D)

Title: Localization in one dimensional lattices with non-nearest-neighbor

hopping: Generalized Anderson and Aubry-Andr\'e models

Authors: J. Biddle, D. J. Priour, B. Wang, S. Das Sarma

Categories: cond-mat.dis-nn quant-ph

Comments: 18 pages, 24 figures

\\

We study the quantum localization phenomena of noninteracting particles in

one-dimensional lattices based on tight-binding models with various forms of

hopping terms beyond the nearest neighbor, which are generalizations of the

famous Aubry-Andr\'e and noninteracting Anderson model. For the case with

deterministic disordered potential induced by a secondary incommensurate

lattice (i.e. the Aubry-Andr\'e model), we identify a class of self dual

models, for which the boundary between localized and extended eigenstates are

determined analytically by employing a generalized Aubry-Andr\'e

transformation. We also numerically investigate the localization properties of

non-dual models with next-nearest-neighbor hopping, Gaussian, and power-law

decay hopping terms. We find that even for these non-dual models, the

numerically obtained mobility edges can be well approximated by the

analytically obtained condition for localization transition in the self dual

models, as long as the decay of the hopping rate with respect to distance is

sufficiently fast. For the disordered potential with genuinely random

character, we examine scenarios with next-nearest-neighbor hopping,

exponential, Gaussian, and power-law decay hopping terms numerically. We find

that the higher order hopping terms can remove the symmetry in the localization

length about the energy band center compared to the Anderson model.

Furthermore, our results demonstrate that for the power-law decay case, there

exists a critical exponent below which mobility edges can be found. Our

theoretical results could, in principle, be directly tested in shallow atomic

optical lattice systems enabling non-nearest-neighbor hopping.

\\ ( http://arxiv.org/abs/1008.0361 , 7200kb)

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arXiv:1008.0423

Date: Mon, 2 Aug 2010 23:17:49 GMT (30kb)

Title: Microscopic Approach to Viscosities in Superfluid Fermi Gases: From BCS

to BEC

Authors: H. Guo, D. Wulin, C. C. Chien, K. Levin

Categories: cond-mat.quant-gas

Comments: 4 pages, 2 figures

Report-no: LA-UR 10-05100

\\

We compute the shear $\eta$ and bulk viscosity $\zeta_2$ in a BCS-BEC

crossover scheme which is demonstrably consistent, via sum rules, with

conservation laws. The onset of a normal state pairing gap and the contribution

from bosonic (non-condensed pair) degrees of freedom lead to a reduction in the

magnitude of these viscosities at general temperatures $T$. When quantitatively

compared with shear viscosity experiments (we independently infer an estimated

lifetime from radio frequency data) the agreement is reasonable, as is a

comparison of $\eta/s$, where $s$ is the trap entropy density.

\\ ( http://arxiv.org/abs/1008.0423 , 30kb)

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arXiv:1008.0428

Date: Tue, 3 Aug 2010 00:31:08 GMT (10kb)

Title: Tonks-Girardeau and Super Tonks-Girardeau States of a Trapped 1D Spinor

Bose Gas

Authors: M.D. Girardeau

Categories: cond-mat.quant-gas

Comments: 4 pages, no figures, revtex4. Submittes to Phys. Rev. A

\\

A harmonically trapped ultracold 1D spin-1 Bose gas with strongly repulsive

or attractive 1D even-wave interactions induced by a 3D Feshbach resonance is

studied. The exact ground state, a hybrid of Tonks-Girardeau (TG) and ideal

Fermi gases, is constructed in the TG limit of infinite even-wave repulsion by

a spinor Fermi-Bose mapping to a spinless ideal Fermi gas. It is then shown

that in the limit of infinite even-wave attraction this same state remains an

exact many-body eigenstate, now highly excited relative to the collapsed

generalized McGuire cluster ground state, showing that the hybrid TG state is

completely stable against collapse to this cluster ground state under a sudden

switch from infinite repulsion to infinite attraction. It is shown to be the TG

limit of a hybrid super Tonks-Girardeau (STG) state which is metastable under a

sudden switch from finite but very strong repulsion to finite but very strong

attraction. It should be possible to create it experimentally by a sudden

switch from strongly repulsive to strongly attractive interaction, as in the

recent Innsbruck experiment on a spin-polarized bosonic STG gas. In the case of

strong attraction there should also exist another STG state of much lower

energy, consisting of strongly bound dimers, a bosonic analog of a recently

predicted STG gas which is an ultracold gas of strongly bound bosonic dimers of

fermionic atoms, but it is shown that this STG state cannot be created by such

a switch from strong repulsion to strong attraction.

\\ ( http://arxiv.org/abs/1008.0428 , 10kb)

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arXiv:1008.0468

Date: Tue, 3 Aug 2010 06:31:17 GMT (163kb)

Title: Equilibration rates and negative absolute temperatures for ultracold

atoms in optical lattices

Authors: Akos Rapp, Stephan Mandt, and Achim Rosch

Categories: cond-mat.quant-gas

\\

As highly tunable interacting systems, cold atoms in optical lattices are

ideal to realize and observe negative absolute temperatures, T < 0. We show

theoretically that by reversing the confining potential, stable superfluid

condensates at finite momentum and T < 0 can be created with low entropy

production for attractive bosons. They may serve as `smoking gun' signatures of

equilibrated T < 0. For fermions, we analyze the time scales needed to

equilibrate to T < 0. For moderate interactions, the equilibration time is

proportional to the square of the radius of the cloud and grows with increasing

interaction strengths as atoms and energy are transported by diffusive

processes.

\\ ( http://arxiv.org/abs/1008.0468 , 163kb)

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arXiv:1008.0489

Date: Tue, 3 Aug 2010 08:58:41 GMT (2074kb)

Title: Dynamical Behaviours of the Nonlinear Atom-Field Interaction in the

Presence of Classical Gravity: f-Deformation Approach

Authors: Sh. Barzanjeh1, M. H. Naderi, and M. Soltanolkotabi

Categories: quant-ph

\\

In this paper, we investigate the effects of a classical gravitational field

on the dynamical behaviour of nonlinear atom-field interaction within the

framework of the f-deformed Jaynes-Cummings model. For this purpose, we first

introduce a set of new atomic operators obeying an f-deformed su(2) algebraic

structure to derive an effective Hamiltonian for the system under

consideration. Then by solving the Schrodinger equation in the interaction

picture and considering certain initial quantum states for the atomic and

radiation subsystems, we analyze the influence of gravity on the temporal

evolution of the atomic population inversion, atomic dipole squeezing, atomic

momentum diffusion, photon counting statistics, and deformed quadrature

squeezing of the radiation field.

\\ ( http://arxiv.org/abs/1008.0489 , 2074kb)

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arXiv:1008.0529

Date: Tue, 3 Aug 2010 12:10:47 GMT (46kb)

Title: Paired phases and Bose-Einstein condensation of spin-one bosons with

attractive interaction

Authors: G. Pelka, K. Byczuk, J. Tworzydlo

Categories: cond-mat.quant-gas

Comments: 9 pages, 4 figures

\\

We analyze paired phases of cold bosonic atoms with the hyper spin S=1 and

with an attractive interaction. We derive mean-field self-consistent equations

for the matrix order parameter describing such paired bosons on an optical

lattice. The possible solutions are classified according to their symmetries.

In particular, we find that the self-consistent equations for the SO(3)

symmetric phase are of the same form as those for the scalar bosons with the

attractive interaction. This singlet phase may exhibit either the BCS type

pairing instability (BCS phase) or the BEC quasiparticle condensation together

with the BCS type pairing (BEC phase) for an arbitrary attraction U_0 in the

singlet channel of the two body interaction. We show that both condensate

phases become stable if a repulsion U_2 in the quintet channel is above a

critical value, which depends on U_0 and other thermodynamic parameters.

\\ ( http://arxiv.org/abs/1008.0529 , 46kb)

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arXiv:1008.0551

Date: Tue, 3 Aug 2010 14:01:26 GMT (453kb)

Title: Universal few-body physics in a harmonic trap

Authors: S. T\"olle, H.-W. Hammer, B.C. Metsch (Bonn Univ.)

Categories: cond-mat.quant-gas nucl-th

Comments: 19 pages, 10 figures

Report-no: HISKP-TH-10-20, INT-PUB-10-036

\\

Few-body systems with resonant short-range interactions display universal

properties that do not depend on the details of their structure or their

interactions at short distances. In the three-body system, these properties

include the existence of a geometric spectrum of three-body Efimov states and a

discrete scaling symmetry. Similar universal properties appear in 4-body and

possibly higher-body systems as well. We set up an effective theory for

few-body systems in a harmonic trap and study the modification of universal

physics for 3- and 4-particle systems in external confinement. In particular,

we focus on systems where the Efimov effect can occur and investigate the

dependence of the 4-body spectrum on the experimental tuning parameters.

\\ ( http://arxiv.org/abs/1008.0551 , 453kb)

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arXiv:1008.0589 (*cross-listing*)

Date: Tue, 3 Aug 2010 16:36:37 GMT (410kb)

Title: Density of states in an optical speckle potential

Authors: G.M. Falco, Andrei A. Fedorenko, Jacopo Giacomelli, Michele Modugno

Categories: cond-mat.dis-nn cond-mat.quant-gas physics.optics

Comments: 11 pages, 11 figures, revtex4

\\

We study the single particle density of states of a one-dimensional speckle

potential, which is correlated and non-Gaussian. We consider both the repulsive

and attractive cases. The system is controlled by a single dimensionless

parameter determined by the mass of the particle, the correlation length and

the average intensity of the field. Depending on the value of this parameter,

the system exhibits different regimes, characterized by the localization

properties of the eigenfunctions. We calculate the corresponding density of

states using the statistical properties of the speckle potential. We find good

agreement with the results of numerical simulations.

\\ ( http://arxiv.org/abs/1008.0589 , 410kb)

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arXiv:1008.0598

Date: Tue, 3 Aug 2010 17:26:49 GMT (47kb)

Title: Magnetic phases of spin-3/2 fermions on a spatially anisotropic square

lattice

Authors: A. K. Kolezhuk and T. Vekua

Categories: cond-mat.quant-gas

Comments: 10 Revtex pages, 5 figures

\\

We study the magnetic phase diagram of spin-3/2 fermions in a spatially

anisotropic square optical lattice at quarter filling (corresponding to one

particle per lattice site). In the limit of the large on-site repulsion the

system can be mapped to the so-called Sp(N) Heisenberg spin model with N=4. We

analyze the Sp(N) spin model with the help of the large-N field-theoretical

approach and show that the effective theory corresponds to the Sp(N) extension

of the CP^{N-1} model, with the Lorentz invariance generically broken. We

obtain the renormalization flow of the model couplings and show that although

the Sp(N) terms are seemingly irrelevant, their presence leads to a

renormalization of the CP^{N-1} part of the action, driving a phase transition.

We further consider the influence of the external magnetic field (the quadratic

Zeeman effect), and present the qualitative analysis of the ground state phase

diagram.

\\ ( http://arxiv.org/abs/1008.0598 , 47kb)

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arXiv:1008.0610

Date: Tue, 3 Aug 2010 18:07:26 GMT (372kb)

Title: Pulse pair generation from coherently prepared atomic ensembles

Authors: D. Moretti, D. Felinto, and J. W. R. Tabosa

Categories: quant-ph physics.atom-ph physics.optics

Comments: 9 pages, 6 figures

Journal-ref: Published online on European Physical Journal D (2010)

DOI: 10.1140/epjd/e2010-00200-y

\\

We report a detailed investigation on the generation of pulse pairs during

the readout of a coherence grating stored in a cold atomic ensemble. The pulse

shapes and the split of the retrieved energy between the two pulses are studied

as a function of the relative intensities of the two reading fields, and a

minimum is observed for the total retrieved energy. We introduce a simplified

analytical theory for the process, considering a three-level atomic system,

which explains all the most striking experimental features.

\\ ( http://arxiv.org/abs/1008.0610 , 372kb)

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arXiv:1008.0677

Date: Wed, 4 Aug 2010 00:21:10 GMT (765kb)

Title: Resonant atom-field interaction in large-size coupled-cavity arrays

Authors: Francesco Ciccarello

Categories: quant-ph

Comments: 8 pages, 4 figures

\\

We consider an array of coupled cavities with staggered inter-cavity

couplings, where each cavity mode interacts with an atom. In contrast to

large-size arrays with uniform-hopping rates where the atomic dynamics is known

to be frozen in the strong-hopping regime, we show that resonant atom-field

dynamics with significant energy exchange can occur in the case of staggered

hopping rates even in the thermodynamic limit. This effect arises from the

joint emergence of an energy gap in the free photonic dispersion relation and a

discrete frequency at the gap's center. The latter corresponds to a bound

normal mode stemming solely from the finiteness of the array length. Depending

on which cavity is excited, either the atomic dynamics is frozen or a

Jaynes-Cummings-like energy exchange is triggered between the bound photonic

mode and its atomic analogue. As these phenomena are effective with any number

of cavities, they are prone to be experimentally observed even in small-size

arrays.

\\ ( http://arxiv.org/abs/1008.0677 , 765kb)

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\\

arXiv:1008.0708

Date: Wed, 4 Aug 2010 07:02:23 GMT (1081kb)

Title: Expansion of matter waves in static and driven periodic potentials

Authors: C.E. Creffield, F. Sols, D. Ciampini, O. Morsch, and E. Arimondo

Categories: cond-mat.quant-gas

Comments: 4 pages, 3 eps figures

\\

We study the non-equilibrium dynamics of cold atoms held in an optical

lattice potential. The expansion of an initially confined atom cloud occurs in

two phases: an initial quadratic expansion followed by a ballistic behaviour at

long times. Accounting for this gives a good description of recent experimental

results, and provides a robust method to extract the effective intersite

tunneling from time-of-flight measurements.

\\ ( http://arxiv.org/abs/1008.0708 , 1081kb)

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\\

arXiv:1008.0714

Date: Wed, 4 Aug 2010 08:38:44 GMT (235kb)

Title: Analytical approach to relaxation dynamics of condensed Bose gases

Authors: Miguel Escobedo, Federica Pezzotti, and Manuel Valle

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

Comments: 25 pages, 3 figures

\\

The temporal evolution of a perturbation of the equilibrium distribution of a

condensed Bose gas is investigated using the kinetic equation which describes

collision between condensate and noncondensate atoms. The dynamics is studied

in the low momentum limit where an analytical treatment is feasible. Explicit

results are given for the behavior at large times in different temperature

regimes.

\\ ( http://arxiv.org/abs/1008.0714 , 235kb)

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\\

arXiv:1008.0788 (*cross-listing*)

Date: Wed, 4 Aug 2010 14:27:31 GMT (241kb)

Title: Number-conserving master equation theory for a dilute Bose-Einstein

condensate

Authors: Alexej Schelle, Thomas Wellens, Dominique Delande, and Andreas

Buchleitner

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

\\

We describe the transition of $N$ weakly interacting atoms into a

Bose-Einstein condensate within a number-conserving quantum master equation

theory. Based on the separation of time scales for condensate formation and

non-condensate thermalization, we derive a master equation for the condensate

subsystem in the presence of the non-condensate environment under the inclusion

of all two body interaction processes. We numerically monitor the condensate

particle number distribution during condensate formation, and derive a

condition under which the unique equilibrium steady state of a dilute, weakly

interacting Bose-Einstein condensate is given by a Gibbs-Boltzmann thermal

state of $N$ non-interacting atoms.

\\ ( http://arxiv.org/abs/1008.0788 , 241kb)

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\\

arXiv:1008.0847 (*cross-listing*)

Date: Wed, 4 Aug 2010 19:08:38 GMT (394kb)

Title: Atomic Dipole Traps with Amplified Spontaneous Emission: A Proposal

Authors: Jean-Fran\c{c}ois Cl\'ement, V\'eronique Zehnl\'e, Jean Claude

Garreau, Pascal Szriftgiser

Categories: quant-ph physics.atom-ph

\\

We propose what we believe to be a novel type of optical source for

ultra-cold atomic Far Off-Resonance optical-dipole Traps (FORTs). The source is

based on an Erbium Amplified Spontaneous Emission (ASE) source that seeds a

high power Erbium Doped Fiber Amplifier (EDFA). The main interest of this

source is its very low coherence length, thus allowing an incoherent

superposition of several trapping beams without any optical interference. The

behavior of the superimposed beams is then a scalar sum greatly simplifying

complex configurations. As an illustration, we report an estimation of the

intensity noise of this source and an estimation of the atomic excess heating

rate for an evaporative cooling experiment application. They are both found to

be suitable for cold atoms experiments.

\\ ( http://arxiv.org/abs/1008.0847 , 394kb)

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\\

arXiv:1008.0894

Date: Thu, 5 Aug 2010 00:18:13 GMT (109kb)

Title: Phase Diagram for a 2-D Two-Temperature Diffusive XY Model

Authors: Matthew D. Reichl, Charo I. Del Genio, and Kevin E. Bassler

Categories: cond-mat.stat-mech

Comments: 5 pages, 4 figures

\\

Using Monte Carlo simulations, we determine the phase diagram of a diffusive

two-temperature XY model. When the two temperatures are equal the system

becomes the equilibrium XY model with the continuous Kosterlitz-Thouless (KT)

vortex-antivortex unbinding phase transition. When the two temperatures are

unequal the system is driven by an energy flow through the system from the

higher temperature heat-bath to the lower temperature one and reaches a

far-from-equilibrium steady state. We show that the nonequilibrium phase

diagram contains three phases: A homogenous disordered phase and two phases

with long range, spin-wave order. Two critical lines, representing continuous

phase transitions from a homogenous disordered phase to two phases of long

range order, meet at the equilibrium the KT point. The shape of the

nonequilibrium critical lines as they approach the KT point is described by a

crossover exponent of phi = 2.52 \pm 0.05. Finally, we suggest that the

transition between the two phases with long-range order is first-order, making

the KT-point where all three phases meet a bicritical point.

\\ ( http://arxiv.org/abs/1008.0894 , 109kb)

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\\

arXiv:1008.0962

Date: Thu, 5 Aug 2010 12:28:00 GMT (1732kb,D)

Title: Non-locality of Two Ultracold Trapped Atoms

Authors: Thom\'as Fogarty, John Goold, Mauro Paternostro and Thomas Busch

Categories: quant-ph

Comments: 14 pages, 7 figures

\\

We undertake a detailed analysis of the non-locality properties of the

fundamental problem of two trapped, distinguishable neutral atoms undergoing

s-wave scattering. We show that this interaction generates continuous variable

(CV) entanglement between the external degrees of freedom of the atoms and

consider its behaviour as a function of both, the distance between the

particles and the strength of the inter-particle scattering length. We first

quantify the entanglement in the ground state of the system at zero temperature

and then, adopting a phase-space approach, test the violation of the

Clauser-Horn-Shimony-Holt inequality at both zero and non-zero temperature and

under the effects of general dissipative local environments.

\\ ( http://arxiv.org/abs/1008.0962 , 1732kb)

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\\

arXiv:1008.0970

Date: Thu, 5 Aug 2010 13:37:10 GMT (100kb)

Title: Stochastic simulations of fermionic dynamics with phase-space

representations

Authors: M. Ogren, K. V. Kheruntsyan, J. F. Corney

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

\\

A Gaussian operator basis provides a means to formulate phase-space

simulations of the real- and imaginary-time evolution of quantum systems. Such

simulations are guaranteed to be exact while the underlying distribution

remains well-bounded, which defines a useful simulation time. We analyse the

application of the Gaussian phase-space representation to the dynamics of the

dissociation of an ultra-cold molecular gas. We show how the choice of mapping

to stochastic differential equations can be used to tailor the stochastic

behaviour, and thus the useful simulation time. In the phase-space approach, it

is only averages of stochastic trajectories that have a direct physical

meaning. Whether particular constants of the motion are satisfied by individual

trajectories depends on the choice of mapping, as we show in examples.

\\ ( http://arxiv.org/abs/1008.0970 , 100kb)

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\\

arXiv:1008.0987

Date: Thu, 5 Aug 2010 14:46:00 GMT (331kb)

Title: Spatial Light Modulators for the Manipulation of Individual Atoms

Authors: Lukas Brandt, Cecilia Muldoon, Tobias Thiele, Jian Dong, Edouard

Brainis and Axel Kuhn

Categories: physics.atom-ph physics.optics quant-ph

Comments: 9 pages, 5 figures

\\

We propose a novel dipole trapping scheme using spatial light modulators

(SLM) for the manipulation of individual atoms. The scheme uses a high

numerical aperture microscope to map the intensity distribution of a SLM onto a

cloud of cold atoms. The regions of high intensity act as optical dipole force

traps. With a SLM fast enough to modify the trapping potential in real time,

this technique is well suited for the controlled addressing and manipulation of

arbitrarily selected atoms.

\\ ( http://arxiv.org/abs/1008.0987 , 331kb)

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The replacements:

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\\

arXiv:1006.2646 (*cross-listing*)

replaced with revised version Fri, 30 Jul 2010 06:45:09 GMT (197kb)

Title: Crossover in the Efimov spectrum

Authors: Ludovic Pricoupenko (LPTMC)

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

Comments:

\\ ( http://arxiv.org/abs/1006.2646 , 197kb)

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\\

arXiv:0911.0812

replaced with revised version Fri, 30 Jul 2010 12:21:50 GMT (1650kb)

Title: Enhanced frequency up-conversion in Rb vapor

Authors: A. Vernier, S. Franke-Arnold, E. Riis and A. S. Arnold

Categories: physics.atom-ph

Comments: 6 pages, 4 figures. Modified to include referees' improvements

Journal-ref: Opt. Express 18, 17020 (2010)

DOI: 10.1364/OE.18.017020

\\ ( http://arxiv.org/abs/0911.0812 , 1650kb)

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\\

arXiv:0812.3718

replaced with revised version Fri, 30 Jul 2010 15:35:39 GMT (211kb)

Title: Universal 1+2-body bound states in planar atomic wave guides

Authors: Ludovic Pricoupenko (LPTMC), Paolo Pedri (LPTMC, LPL)

Categories: cond-mat.other

Comments:

\\ ( http://arxiv.org/abs/0812.3718 , 211kb)

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\\

arXiv:1005.5174

replaced with revised version Fri, 30 Jul 2010 18:02:31 GMT (588kb)

Title: Spin transport in coupled spinor Bose gases

Authors: J.M. McGuirk

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

\\ ( http://arxiv.org/abs/1005.5174 , 588kb)

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\\

arXiv:1007.5061

replaced with revised version Fri, 30 Jul 2010 22:32:02 GMT (211kb)

Title: Superfluidity and dimerization in a multilayered system of fermionic

polar molecules

Authors: Andrew C. Potter, Erez Berg, Daw-Wei Wang, Bertrand I. Halperin,

Eugene Demler

Categories: cond-mat.quant-gas

Comments: 4+epsilon pages

\\ ( http://arxiv.org/abs/1007.5061 , 211kb)

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\\

arXiv:0905.0343 (*cross-listing*)

replaced with revised version Sat, 31 Jul 2010 03:47:17 GMT (1665kb)

Title: Role of spatial inhomogeneity in dissociation of trapped molecular

condensates

Authors: Magnus Ogren and K. V. Kheruntsyan

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

Comments: Final published version; 23 pages, 13 figures

Journal-ref: Phys. Rev. A 82, 013641 (2010)

DOI: 10.1103/PhysRevA.82.013641

\\ ( http://arxiv.org/abs/0905.0343 , 1665kb)

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\\

arXiv:1007.4926

replaced with revised version Mon, 2 Aug 2010 07:03:32 GMT (201kb)

Title: Critical Exponents and Universality in Bose-Einstein Condensation

Authors: Sanchari Goswami, Tapan Kumar Das and Anindya Biswas

Categories: cond-mat.quant-gas

Comments: reference added in version 2

\\ ( http://arxiv.org/abs/1007.4926 , 201kb)

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\\

arXiv:0912.4349

replaced with revised version Mon, 2 Aug 2010 07:24:00 GMT (101kb)

Title: Not all pure entangled states are useful for sub shot-noise

interferometry

Authors: Philipp Hyllus, Otfried G\"uhne, and Augusto Smerzi

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

Comments: Published version, significantly revised according to the referee's

comments. Results unchanged

Journal-ref: Phys. Rev. A 82, 012337 (2010)

\\ ( http://arxiv.org/abs/0912.4349 , 101kb)

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\\

arXiv:0904.4334

replaced with revised version Mon, 2 Aug 2010 14:26:31 GMT (46kb)

Title: Spin-1/2 fermions with attractive interaction in an optical lattice

Authors: O. Fialko, A. Gammal, K. Ziegler

Categories: cond-mat.quant-gas

Comments: 10 pages, 7 figures; revised

Journal-ref: Phys. Lett. A, 2010

DOI: 10.1016/j.physleta.2010.07.038

\\ ( http://arxiv.org/abs/0904.4334 , 46kb)

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\\

arXiv:1007.3200

replaced with revised version Mon, 2 Aug 2010 15:49:42 GMT (500kb,D)

Title: Bose-Einstein condensation at finite momentum and magnon condensation in

thin film ferromagnets

Authors: Johannes Hick, Francesca Sauli, Andreas Kreisel, Peter Kopietz

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

Comments: 9 pages, 4 figures, some typos corrected

\\ ( http://arxiv.org/abs/1007.3200 , 500kb)

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\\

arXiv:1006.2042

replaced with revised version Mon, 2 Aug 2010 19:40:12 GMT (94kb)

Title: Role of interactions in time-of-flight expansion of atomic clouds from

optical lattices

Authors: Joern N. Kupferschmidt (Cornell, Berlin), Erich J. Mueller (Cornell)

Categories: cond-mat.quant-gas

Comments: 6 pages, 3 figures

\\ ( http://arxiv.org/abs/1006.2042 , 94kb)

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\\

arXiv:1007.5339

replaced with revised version Tue, 3 Aug 2010 08:20:09 GMT (2636kb,D)

Title: Atom chips with two-dimensional electron gases: near surface trapping

and ultracold-atom microscopy of quantum electronic systems

Authors: G. Sinuco-Le\'on and B. Kaczmarek and P. Kr\"uger and T.M. Fromhold

Categories: cond-mat.quant-gas

Comments: 5 pages, 4 figures

\\ ( http://arxiv.org/abs/1007.5339 , 2636kb)

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\\

arXiv:1008.0514

replaced with revised version Wed, 4 Aug 2010 02:52:52 GMT (73kb)

Title: Anisotropic Superfluidity in the Two-Species Polar Fermi Gas

Authors: Renyuan Liao and Joachim Brand

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

Comments: 4 pages, 5 figures

\\ ( http://arxiv.org/abs/1008.0514 , 73kb)

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\\

arXiv:1006.4817

replaced with revised version Wed, 4 Aug 2010 11:28:28 GMT (12kb)

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

condensation?

Authors: B.V.Vasiliev

Categories: cond-mat.supr-con

\\ ( http://arxiv.org/abs/1006.4817 , 12kb)

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\\

arXiv:1007.5187

replaced with revised version Wed, 4 Aug 2010 19:01:22 GMT (343kb)

Title: Intercepts of the momentum correlation functions in \mu-Bose gas model

and their asymptotics

Authors: A.M. Gavrilik, A.P. Rebesh

Categories: quant-ph cond-mat.stat-mech hep-ph nucl-th

Comments: 11 pages (two column), 3 figures; v.2: small changes (in Abstract,

Introduction, Conclusions), ref. added

\\ ( http://arxiv.org/abs/1007.5187 , 343kb)

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\\

arXiv:1002.3925

replaced with revised version Thu, 5 Aug 2010 05:48:16 GMT (129kb)

Title: Critical velocity of flowing supersolids of dipolar Bose gases in

optical lattices

Authors: Ippei Danshita, Daisuke Yamamoto

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

Comments: 7 pages, 4 figures, published version

Journal-ref: Phys. Rev. A 82, 013645 (2010)

\\ ( http://arxiv.org/abs/1002.3925 , 129kb)

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\\

arXiv:1008.0845

replaced with revised version Thu, 5 Aug 2010 11:41:51 GMT (548kb)

Title: Relative number squeezing in four-wave mixing of matter waves

Authors: Jean-Christophe Jaskula, Marie Bonneau, Guthrie B. Partridge,

Valentina Krachmalnicoff, Piotr Deuar, Karen V. Kheruntsyan, Alain Aspect,

Denis Boiron, Christoph I. Westbrook

Categories: cond-mat.quant-gas

Comments: 4 pages, 3 figures

\\ ( http://arxiv.org/abs/1008.0845 , 548kb)

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\\

arXiv:1003.2071

replaced with revised version Thu, 5 Aug 2010 17:27:26 GMT (133kb,D)

Title: Dynamical Phase Transitions and Instabilities in Open Atomic Many-Body

Systems

Authors: Sebastian Diehl, Andrea Tomadin, Andrea Micheli, Rosario Fazio, Peter

Zoller

Categories: cond-mat.quant-gas

Comments: 4+ pages, 3 figures

Journal-ref: Phys. Rev. Lett. 105, 015702 (2010)

DOI: 10.1103/PhysRevLett.105.015702

\\ ( http://arxiv.org/abs/1003.2071 , 133kb)

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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 Wed Oct 20 2010 - 09:28:34 EST

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