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

Date: Wed, 20 May 2009 16:57:41 +1000

Date: Wed, 20 May 2009 16:57:41 +1000

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

Dear subscribers,

Mike Garrett deserves our thanks for preparing this week's arXiv selection.

There are 34 new preprints and 17 replacements:

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arXiv:0903.1269

Date: Fri, 6 Mar 2009 18:06:33 GMT (1356kb)

Title: Intrinsic and dislocation induced elastic behavior of solid helium

Authors: James Day, Oleksandr Syshchenko, and John Beamish

Categories: cond-mat.other

\\

Recent experiments showed that the shear modulus of solid 4He stiffens in the

same temperature range (below 200 mK) where mass decoupling and supersolidity

have been inferred from torsional oscillator measurements. The two phenomena

are clearly related and crystal defects, particularly dislocations, appear to

be involved in both. We have studied the effects of annealing and the effects

of applying large stresses on the elastic properties of solid 4He, using both

acoustic resonances and direct low-frequency and low-amplitude measurements of

the shear modulus. Both annealing and stressing affect the shear modulus, as

expected if dislocations are responsible. However, it is the high temperature

modulus which is affected; the low temperature behavior is unchanged and

appears to reflect the intrinsic modulus of solid helium. We interpret this

behavior in terms of dislocations which are pinned by isotopic 3He impurities

at low temperatures and so have no effect on the shear modulus. At higher

temperatures they become mobile and weaken the solid. Stressing the crystal at

low temperatures appears to introduce new defects or additional pinning sites

for the dislocation network but these effects can be reversed by heating the

crystal above 500 mK. This is in contrast to dislocations produced during

crystal growth, which are only annealed at temperatures close to melting.

\\ ( http://arxiv.org/abs/0903.1269 , 1356kb)

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arXiv:0903.1276

Date: Fri, 6 Mar 2009 18:50:14 GMT (1126kb)

Title: Evidence for universal four-body states tied to an Efimov trimer

Authors: F. Ferlaino, S. Knoop, M. Berninger, W. Harm, J. P. D'Incao, H.-C.

N\"agerl, and R. Grimm

Categories: cond-mat.other

Comments: 4 pages, 4 figures

\\

We report on the measurement of four-body recombination rate coefficients in

an atomic gas. Our results obtained with an ultracold sample of cesium atoms at

negative scattering lengths show a resonant enhancement of losses and provide

strong evidence for the existence of a pair of four-body states, which is

strictly connected to Efimov trimers via universal relations. Our findings

confirm recent theoretical predictions and demonstrate the enrichment of the

Efimov scenario when a fourth particle is added to the generic three-body

problem.

\\ ( http://arxiv.org/abs/0903.1276 , 1126kb)

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arXiv:0903.1166

Date: Fri, 6 Mar 2009 08:10:33 GMT (58kb)

Title: Testing General Relativity with Atomic Clocks

Authors: S. Reynaud, C. Salomon and P. Wolf

Categories: quant-ph gr-qc

Comments: Contribution for "The Nature of Gravity" (eds. F. Everitt et al)

\\

We discuss perspectives for new tests of general relativity which are based

on recent technological developments as well as new ideas. We focus our

attention on tests performed with atomic clocks and do not repeat arguments

present in the other contributions to the present volume. In particular, we

present the scientific motivations of the space projects ACES and SAGAS.

\\ ( http://arxiv.org/abs/0903.1166 , 58kb)

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arXiv:0903.1210

Date: Fri, 6 Mar 2009 13:55:15 GMT (50kb)

Title: Generation of entangled coherent states for distant Bose-Einstein

condensates via electromagnetically induced transparency

Authors: Le-Man Kuang, Zeng-Bing Chen, and Jian-Wei Pan

Categories: quant-ph

Comments: 15 pages, 3 figures

Journal-ref: Phys. Rev. A 76, 052324 (2007)

\\

In this paper, we propose a method to generate entangled coherent states

between two spatially separated atomic Bose-Einstein condensates (BECs) via the

technique of the electromagnetically induced transparency (EIT). Two strong

coupling laser beams and two entangled probe laser beams are used to make two

distant BECs be in EIT states and to generate an atom-photon entangled state

between probe lasers and distant BECs. The two BECs are initially in

un-entangled product coherent states while the probe lasers are initially in an

entangled state. Entangled states of two distant BECs can be created through

performing projective measurements upon the two outgoing probe lasers under

certain conditions. Concretely, we propose two protocols to show how to

generate entangled coherent states of the two distant BECs. One is a

single-photon scheme in which an entangled single-photon state serves the

quantum channel to generate entangled distant BECs. The other is a multiphoton

scheme where an entangled coherent state of the probe lasers is used as the

quantum channel. Additionally, we also obtain some atom-photon entangled states

of particular interest such as entangled states between a pair of optical Bell

(or quasi-Bell) states and a pair of atomic entangled coherent (or quasi-Bell)

states.

\\ ( http://arxiv.org/abs/0903.1210 , 50kb)

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arXiv:0903.0895 s

Date: Thu, 5 Mar 2009 16:04:41 GMT (654kb)

Title: Quantum Quench from a Thermal Initial State

Authors: Spyros Sotiriadis, Pasquale Calabrese, John Cardy

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

Comments: 8 pages, 3 figures

\\

We consider a quantum quench in a system of free bosons, starting from a

thermal initial state. As in the case where the system is initially in the

ground state, any finite subsystem eventually reaches a stationary thermal

state with a momentum-dependent effective temperature. Remarkably enough, we

find that this can, in some cases, even be lower than the initial temperature.

We also study lattice effects and discuss more general types of quenches.

\\ ( http://arxiv.org/abs/0903.0895 , 654kb)

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arXiv:0903.1222

Date: Fri, 6 Mar 2009 15:08:36 GMT (655kb)

Title: Molecular vibrational cooling by Optical Pumping with shaped femtosecond

pulses

Authors: Dimitris Sofikitis (LAC), Sebastien Weber (LCAR), Andr\'ea Fioretti

(LAC), Ridha Horchani (LAC), Maria Allegrini (LAC, CNISM), B\'eatrice Chatel

(LCAR), Daniel Comparat (LAC), Pierre Pillet (LAC)

Categories: physics.atom-ph

Comments: TO be published in New Journal of Physics

\\

Some of us have recently reported in Science 321 232 (2008) vibrational

cooling of translationally cold Cs_2 molecules into the lowest vibrational

level v=0 of the singlet X 1Sigma_g ground electronic state. Starting from a

sample of cold molecules produced in a collection of vibrational levels of the

ground state, our method was based on repeated optical pumping by laser light

with a spectrum broad enough to excite all populated vibrational levels but

frequency-limited in such a way to eliminate transitions from v=0 level, in

which molecules accumulate. In this paper this method is generalized to

accumulate molecules into an arbitrary selected "target" vibrational level. It

is implemented by using ultrashort pulse shaping techniques based on Liquid

Crystal spatial light modulator. In particular a large fraction of the

initially present molecule is transferred into a selected vibrational level

such as v=1, 2 and 7. Limitations of the method as well as the possible

extension to rotational cooling are also discussed.

\\ ( http://arxiv.org/abs/0903.1222 , 655kb)

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arXiv:0903.1163

Date: Fri, 6 Mar 2009 08:02:16 GMT (7kb)

Title: Dark states of dressed spinor Bose-Einstein condensates of spin-1 atoms

Authors: Ma Luo, Chengguang Bao, Zhibing Li

Categories: physics.atm-clus physics.optics

Comments: 4 pages

\\

Dressed states of spinor Bose-Einstein condensates of spin-1 atoms located in

optical cavity of near resonance frequency of excited state of the atom are

investigated. The wave function of dark states are given.

\\ ( http://arxiv.org/abs/0903.1163 , 7kb)

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arXiv:0903.1309

Date: Fri, 6 Mar 2009 22:43:54 GMT (333kb)

Title: Simulation of complete many-body quantum dynamics using controlled

quantum-semiclassical hybrids

Authors: Piotr Deuar

Categories: cond-mat.other

Comments: 4+4 pages, 10 figures

\\

A controlled hybridization between full quantum dynamics and semiclassical

approaches (mean-field and truncated Wigner) is implemented for interacting

many-boson systems. One obtains continuous families of evolution equations that

interpolate smoothly between the (exact) positive-P representation and the

other incomplete treatments. It is then demonstrated how simulating these

hybrid equations allows one to obtain the full quantum dynamics for much longer

times than is possible using the exact treatment directly. This is demonstrated

on the realistic case of a collision of sodium BECs with 1.5x10^5 atoms. The

uncertainty of physical quantities remains well characterised because no ad-hoc

cutoffs are introduced in the description of the system. Extension to other

physical systems is discussed.

\\ ( http://arxiv.org/abs/0903.1309 , 333kb)

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arXiv:0903.1326

Date: Sat, 7 Mar 2009 06:38:51 GMT (353kb)

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

about 75 mK

Authors: Andrey Penzev, Nobutaka Shimizu, Yoshinori Yasuta, and Minoru Kubota

Categories: cond-mat.other

Comments: 4 pages, 5 figures

\\

A detailed torsional oscillator (TO) study on a stable solid 4He sample at 49

bar with To = 0.5K, is reported to T below the dissipation peak at Tp . We find

hysteretic behavior starting below Tc = about 75 mK, in period shift, as well

as in dissipation, with changes of AC excitation amplitude Vac . The derived

difference of non-linear rotational susceptibility DeltaNLRS(T)hys across the

hysteresis loop under a systematic condition is analyzed as a function of Vac

and T . We propose that DeltaN LRS(T)hys is proportional to non- classical

rortational inertia fraction, NCRIF, and is actually the supersolid density

rho_ss of the 3D supersolid state below Tc . rho_ss changes linearly with T

down to about 60 mK and then increases much more steeply, and approaching a

finite value towards T = 0. We find an AC velocity of 40 micrometer/s beyond

which the hysteresis starts at T < Tc and a critical AC velocity, about 1 cm/s,

above which rho_ss is completely destroyed. We discuss also the coherence

length of the supersolid.

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

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arXiv:0903.1480

Date: Mon, 9 Mar 2009 05:10:20 GMT (690kb)

Title: A simple mathematical proof of Boltzmann's equal a priori probability

hypothesis

Authors: Denis J. Evans, Debra J. Searles and Stephen R. Williams

Categories: cond-mat.stat-mech

Comments: 12 pages

\\

Using the Fluctuation Theorem (FT), we give a first-principles derivation of

Boltzmann's postulate of equal a priori probability in phase space for the

microcanonical ensemble. Using a corollary of the Fluctuation Theorem, namely

the Second Law Inequality, we show that if the initial distribution differs

from the uniform distribution over the energy hypersurface, then under very

wide and commonly satisfied conditions, the initial distribution will relax to

that uniform distribution. This result is somewhat analogous to the Boltzmann

H-theorem but unlike that theorem, applies to dense fluids as well as dilute

gases and also permits a nonmonotonic relaxation to equilibrium. We also prove

that in ergodic systems the uniform (microcanonical) distribution is the only

stationary, dissipationless distribution for the constant energy ensemble.

\\ ( http://arxiv.org/abs/0903.1480 , 690kb)

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arXiv:0903.1570

Date: Mon, 9 Mar 2009 15:30:25 GMT (1416kb)

Title: Coexisting Non-Equilibrium Condensates with Long-Range Spatial Coherence

in Semiconductor Microcavities

Authors: D. N. Krizhanovskii, K. G. Lagoudakis, M. Wouters, B. Pietka, R. A.

Bradley, K. Guda, D. M. Whittaker, M. S. Skolnick, B. Deveaud-Pledran, M.

Richard, R. Andre, Le Si Dang

Categories: cond-mat.other

Comments: 9 pages, 12 figures

\\

Real and momentum space spectrally resolved images of microcavity polariton

emission in the regime of condensation are investigated under non resonant

excitation using a laser source with reduced intensity fluctuations on the

timescale of the exciton lifetime. We observe that the polariton emission

consists of many macroscopically occupied modes. Lower energy modes are

strongly localized by the photonic potential disorder on a scale of few

microns. Higher energy modes have finite k-vectors and are delocalized over

10-15 microns. All the modes exhibit long range spatial coherence comparable to

their size. We provide a theoretical model describing the behavior of the

system with the results of the simulations in good agreement with the

experimental observations. We show that the multimode emission of the polariton

condensate is a result of its nonequilibrium character, the interaction with

the local photonic potential and the reduced intensity fluctuations of the

excitation laser.

\\ ( http://arxiv.org/abs/0903.1570 , 1416kb)

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arXiv:0903.1591

Date: Mon, 9 Mar 2009 16:42:54 GMT (1486kb)

Title: Thermal and quantum fluctuations in chains of ultracold polar molecules

Authors: G. E. Astrakharchik, Gabriele De Chiara, Giovanna Morigi, and Jordi

Boronat

Categories: cond-mat.mes-hall

Comments: to appear in Special issue on modern applications of trapped ions, J.

Phys. B: At. Mol. Opt. Phys

\\

Ultracold polar molecules, in highly anisotropic traps and interacting via a

repulsive dipolar potential, may form one-dimensional chains at high densities.

According to classical theory, at low temperatures there exists a critical

value of the density at which a second order phase transition from a linear to

a zigzag chain occurs. We study the effect of thermal and quantum fluctuations

on these self-organized structures using classical and quantum Monte Carlo

methods, by means of which we evaluate the pair correlation function and the

static structure factor. Depending on the parameters, these functions exhibit

properties typical of a crystalline or of a liquid system. We compare the

thermal and the quantum results, identifying analogies and differences.

Finally, we discuss experimental parameter regimes where the effects of quantum

fluctuations on the linear - zigzag transition can be observed.

\\ ( http://arxiv.org/abs/0903.1591 , 1486kb)

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arXiv:0903.1621

Date: Mon, 9 Mar 2009 18:38:11 GMT (42kb)

Title: Susceptibility Propagation for Constraint Satisfaction Problems

Authors: Saburo Higuchi and Marc M\'ezard

Categories: cond-mat.dis-nn cond-mat.stat-mech

Comments: 17 pages, 5 figures

\\

We study the susceptibility propagation, a message-passing algorithm to

compute correlation functions. It is applied to constraint satisfaction

problems and its accuracy is examined. As a heuristic method to find a

satisfying assignment, we propose susceptibility-guided decimation where

correlations among the variables play an important role. We apply this novel

decimation to locked occupation problems, a class of hard constraint

satisfaction problems exhibited recently. It is shown that the present method

performs better than the standard belief-guided decimation.

\\ ( http://arxiv.org/abs/0903.1621 , 42kb)

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arXiv:0903.1457

Date: Sun, 8 Mar 2009 21:27:32 GMT (2197kb)

Title: Electromagnetically induced transparency controlled by a microwave field

Authors: Hebin Li, Vladimir A. Sautenkov, Yuri V. Rostovtsev, George R. Welch,

Philip R. Hemmer, and Marlan O. Scully

Categories: quant-ph

Comments: 7 pages, 6 figures

\\

We have experimentally studied propagation of two optical fields in a dense

rubidium (Rb) vapor in the case when an additional microwave field is coupled

to the hyperfine levels of Rb atoms. The Rb energy levels form a close-lambda

three-level system coupled to the optical fields and the microwave field. It

has been found that the maximum transmission of a probe field depends on the

relative phase between the optical and the microwave fields. We have observed

both constructive and destructive interference in electromagnetically induced

transparency (EIT). A simple theoretical model and a numerical simulation have

been developed to explain the observed experimental results.

\\ ( http://arxiv.org/abs/0903.1457 , 2197kb)

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arXiv:0903.1614

Date: Mon, 9 Mar 2009 18:07:39 GMT (1280kb,D)

Title: Quantum interferometry with complex molecules

Authors: Markus Arndt, Klaus Hornberger

Categories: quant-ph

Comments: 29 pages, 11 figures; to appear in "Quantum Coherence in Solid State

Systems", Proceedings of the International School of Physics "Enrico Fermi",

Course CLXXI

\\

This chapter reviews recent experiments on matter wave interferometry with

large molecules. Starting from an elementary introduction to matter wave

physics we discuss far-field diffraction and near-field interferometry with

thermally excited many-body systems. We describe the constraints imposed by

decoherence and dephasing effects, and present an outlook to the future

challenges in macromolecule and cluster interferometry.

\\ ( http://arxiv.org/abs/0903.1614 , 1280kb)

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arXiv:0903.1485

Date: Mon, 9 Mar 2009 06:58:39 GMT (16kb)

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

Photoassoiative Coupling

Authors: B. Deb and J. Harza

Categories: physics.atom-ph physics.optics

Comments: 4 pages 1 figure

\\

We show that it is possible to change not only s-wave but also higher partial

wave atom-atom interactions in cold collision in the presence of relatively

intense laser fields tuned near a photoassociative transition.

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

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arXiv:0903.1608

Date: Mon, 9 Mar 2009 17:47:45 GMT (1024kb,D)

Title: Simulating Hard Rigid Bodies

Authors: Cristiano De Michele

Categories: physics.comp-ph

Comments: 36 pages, 17 figures

\\

Several physical systems in condensed matter have been modeled approximating

their constituent particles as hard objects. In fact, the hard spheres model

has been one of the cornerstones of the computational and theoretical

description in condensed matter. The next level of description is to consider

particles as rigid objects of generic shape enriching enormously the possible

phenomenology. This kind of modeling will be interesting in all the situations

in which steric effect plays a relevant role. These include biology, soft

matter, granular material and molecular systems. Nevertheless, except for the

case of hard spheres systems, there are no general recipes for event-driven

Molecular Dynamics simulations of hard rigid bodies. Two similar algorithms for

calculating the distance between two convex hard rigid bodies and the contact

time of two colliding hard rigid bodies solving non-linear set of equations

will be described. Building on these two methods, an event-driven molecular

dynamics algorithm for simulating systems of convex hard rigid bodies will be

developed and illustrated in details. In order to optimize the collision

detection between very elongated hard rigid bodies, a novel nearest-neighbor

list method based on oriented bounding box will be introduced and fully

explained. Efficiency and performances of the new algorithm proposed will be

extensively tested in the special case of uniaxial hard ellipsoids and

applications in various scientific fields will be reported and discussed.

\\ ( http://arxiv.org/abs/0903.1608 , 1024kb)

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arXiv:0903.1639

Date: Tue, 10 Mar 2009 17:57:02 GMT (487kb)

Title: Superfluid as a powerful light source

Authors: Jinwu Ye, T. Shi, Longhua Jiang and C. P. Sun

Categories: cond-mat.mes-hall cond-mat.mtrl-sci

Comments: 4+ \epsilon pages, 2 color figures, REVTEX4

\\

Superfluid has been realized in Helium-4, Helium-3 and ultra-cold atoms. It

has been widely used in making high-precision devices and also in cooling

various systems. There have been extensive experimental search for possible

exciton superfluid in semiconductor electron-hole bilayer systems below liquid

Helium temperature. However, exciton superfluid are meta-stable and will

eventually decay through emitting photons. Here we show that the light emitted

from the excitonic superfluid has unique and unusual features not shared by any

other atomic or condensed matter systems. These remarkable features can be used

for high precision measurements, quantum information processing and also for

the development of a new generation of powerful opto-electronic devices.

\\ ( http://arxiv.org/abs/0903.1639 , 487kb)

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arXiv:0903.1647

Date: Mon, 9 Mar 2009 20:54:26 GMT (21kb)

Title: Stability of low-dimensional multicomponent Bose gases

Authors: Alexei Kolezhuk

Categories: cond-mat.other cond-mat.str-el

Comments: 4 pages, 2 figures

\\

It is shown that in case of low-dimensional geometries the interactions in

dilute Bose mixtures are strongly renormalized. This leads to a considerable

change of the stability conditions as compared to the mean-field results valid

in the high-density regime. Novel states with only partial phase separation or

collapse are predicted to appear in a certain window of inter-species

interaction and density.

\\ ( http://arxiv.org/abs/0903.1647 , 21kb)

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arXiv:0903.1665

Date: Mon, 9 Mar 2009 23:36:03 GMT (15kb)

Title: Mapping Approach for Quantum-Classical Time Correlation Functions

Authors: Ali Nassimi and Raymond Kapral

Categories: cond-mat.other quant-ph

\\

The calculation of quantum canonical time correlation functions is considered

in this paper. Transport properties, such as diffusion and reaction rate

coefficients, can be determined from time integrals of these correlation

functions. Approximate, quantum-classical expressions for correlation

functions, which are amenable to simulation, are derived. These expressions

incorporate the full quantum equilibrium structure of the system but

approximate the dynamics by quantum-classical evolution where a quantum

subsystem is coupled to a classical environment. The main feature of the

formulation is the use of a mapping basis where the subsystem quantum states

are represented by fictitious harmonic oscillator states. This leads to a full

phase space representation of the dynamics that can be simulated without appeal

to surface-hopping methods. The results in this paper form the basis for new

simulation algorithms for the computation of quantum transport properties of

large many-body systems.

\\ ( http://arxiv.org/abs/0903.1665 , 15kb)

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arXiv:0903.1804

Date: Tue, 10 Mar 2009 19:19:41 GMT (212kb)

Title: Inelastic Collisions of a Fermi Gas in the BEC-BCS Crossover

Authors: X. Du, Y. Zhang, and J. E. Thomas

Categories: cond-mat.other

Comments: 5 pages 4 figures

\\

We report the measurement of inelastic three-body and two-body collisional

decay rates for a two-component Fermi gas of $^6$Li, which are highly

suppressed by the Pauli exclusion principle. Our measurements are made in the

BEC-BCS crossover regime, near the two-body collisional (Feshbach) resonance.

At high temperature (energy) the data shows a dominant three-body decay

process, which is studied as a function of bias magnetic field. At low energy,

the data shows a coexistence of two-body and three-body decay processes near

and below the Feshbach resonance. Below resonance, the observed two-body

inelastic decay can arise from molecule-atom and molecule-molecule collisions.

We suggest that at and above resonance, an effective two-body decay rate arises

from collisions between atoms and correlated (Cooper) pairs that can exist at

sufficiently low temperature.

\\ ( http://arxiv.org/abs/0903.1804 , 212kb)

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arXiv:0903.1736

Date: Tue, 10 Mar 2009 11:27:49 GMT (523kb)

Title: Stationary light in cold atomic gases

Authors: Gor Nikoghosyan and Michael Fleischhauer

Categories: quant-ph

Comments: 6 pages, 5 figures

\\

We discuss stationary light created by a pair of counter-propagating control

fields in Lambda-type atomic gases with electromagnetically induced

transparency for the case of negligible Doppler broadening. In this case the

secular approximation used in the discussion of stationary light in hot vapors

is no longer valid. We discuss the quality of the effective light-trapping

system and show that in contrast to previous claims it is finite even for

vanishing ground-state dephasing. The dynamics of the photon loss is in general

non exponential and can be faster or slower than in hot gases.

\\ ( http://arxiv.org/abs/0903.1736 , 523kb)

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arXiv:0807.5062 (*cross-listing*)

Date: Thu, 31 Jul 2008 13:46:29 GMT (51kb)

Date (revised v2): Wed, 15 Oct 2008 21:03:06 GMT (51kb)

Date (revised v3): Tue, 10 Mar 2009 06:21:12 GMT (51kb)

Title: Atom-atom correlations in colliding Bose-Einstein condensates

Authors: Magnus Ogren and K. V. Kheruntsyan

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

Comments: Minor corrections to the text; final published version

Journal-ref: Phys. Rev. A 79, 021606(R) (2009)

\\

We analyze atom-atom correlations in the s-wave scattering halo of two

colliding condensates. By developing a simple perturbative approach, we obtain

explicit analytic results for the collinear (CL) and back-to-back (BB)

correlations corresponding to realistic density profiles of the colliding

condensates with interactions. The results in the short time limit are in

agreement with the first-principles simulations using the positive-$P$

representation and provide analytic insights into the experimental observations

of Perrin et al. [Phys. Rev. Lett. 99, 150405 (2007)]. For long collision

durations, we predict that the BB correlation becomes broader than the CL

correlation.

\\ ( http://arxiv.org/abs/0807.5062 , 51kb)

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arXiv:0903.1660

Date: Mon, 9 Mar 2009 22:40:55 GMT (13kb)

Title: Calculation of Stark-induced absorption on the 6s6p ^3P_1 - 6s^2 ^1S_0

transition in Hg

Authors: K. Beloy, V. A. Dzuba, A. Derevianko

Categories: physics.atom-ph

Comments: 5 pages

\\

We carry out relativistic many-body calculations of the Stark-induced

absorption coefficient on the 254-nm $6s6p ^3P_1 (F=1/2) - 6s^2 ^1S_0$ line of

$^{199}$Hg atom, the effect considered before by Lamoreaux and Fortson using a

simple central field estimate [Phys. Rev. A {\bf 46}, 7053 (1992)]. The

Stark-induced admixing of states of opposite parity opens additional M1 and E2

transition channels. We find that the resulting M1-E1 absorption dominates over

E2-E1 absorption. The value of the E2-E1 absorption coefficient depends

strongly on the details of treatment of the correlation problem. As a result,

our numerical values differ substantially from those of the earlier central

field calculation. Reliable calculation of this effect can enable a useful

experimental check on the optical technique being used to search for a

permanent electric dipole moment of the $^{199}$Hg atom.

\\ ( http://arxiv.org/abs/0903.1660 , 13kb)

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arXiv:0903.1898

Date: Wed, 11 Mar 2009 03:06:00 GMT (344kb)

Title: Heat capacity peak in solid 4He: Effects of disorder and 3He impurities

Authors: X. Lin, A. C. Clark, Z. G. Cheng and M. H. W. Chan

Categories: cond-mat.other

Comments: 14 pages, 3 figures

\\

Heat capacity measurements with significantly improved resolution find the

presence of a peak in a solid 4He sample in coexistence with liquid. With

improved crystallinity, the peak decreases in height and moves to lower

temperature. A hysteretic heat capacity signature consistent with 3He-4He phase

separation, not detected in an earlier work is clearly observed.

\\ ( http://arxiv.org/abs/0903.1898 , 344kb)

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arXiv:0903.1902

Date: Wed, 11 Mar 2009 03:59:54 GMT (138kb)

Title: Spin-structures of N-boson systems with nonzero spins - an analytically

solvable model with pairing force

Authors: Chengguang Bao

Categories: cond-mat.other

Comments: 10 pages, 2 figures, accepted by Few-Body Systems

\\

A model is proposed to study the possible pairing structures of N-boson

systems with nonzero spin. Analytical solutions have been obtained. The

emphasis is placed on the spin-structures of ground states with attractive or

repulsive pairing force, and with or without the action of a magnetic field. A

quantity (an analogue of the two-body density function) is defined to study the

spin-correlation between two bosons in N-body systems. The excitation of the

system has also been studied.

\\ ( http://arxiv.org/abs/0903.1902 , 138kb)

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arXiv:0903.1912

Date: Wed, 11 Mar 2009 06:16:01 GMT (141kb)

Title: Heat Transport in Magnon Bose-Einstein-Condensation State of a

Low-Dimensional Quantum Magnet

Authors: X. F. Sun, W. Tao, X. M. Wang, C. Fan

Categories: cond-mat.str-el

Comments: 5 pages, 4 figures

\\

We report a study of the low-temperature thermal conductivity of

NiCl_{2}-4SC(NH_{2})_{2}, which is a spin-1 chain system exhibiting the magnon

Bose-Einstein condensation (BEC) in magnetic field. It is found that the low-T

thermal conductivity along the spin-chain direction shows strong anomalies at

the lower and upper critical fields of the magnon BEC state. In this state,

magnons act mainly as phonon scatterers at relatively high temperature, but

change their role to heat carriers upon temperature approaching zero. The

result demonstrates a large thermal conductivity in the magnon BEC state and

points to a direct analog between the magnon BEC and the conventional one.

\\ ( http://arxiv.org/abs/0903.1912 , 141kb)

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arXiv:0903.1931

Date: Wed, 11 Mar 2009 09:04:33 GMT (521kb)

Title: The effect of population imbalance on the

Berezinskii-Kosterlitz-Thouless phase transition in a superfluid Fermi gas

Authors: J. Tempere, S.N. Klimin, J.T. Devreese

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

Comments: 3 figures

\\

The Berezinskii-Kosterlitz-Thouless (BKT) mechanism describes the breakdown

of superfluidity in a two-dimensional Bose gas or a two-dimensional gas of

paired fermions. In the latter case, a population imbalance between the two

pairing partners in the Fermi mixture is known to influence pairing

characteristics. Here, we investigate the effects of imbalance on the

two-dimensional BKT superfluid transition, and show that superfluidity is even

more sensitive to imbalance than for three dimensional systems.

Finite-temperature phase diagrams are derived using the functional integral

formalism in combination with a hydrodynamic action functional for the phase

fluctuations. This allow to identify a phase separation region and tricritical

points due to imbalance. In contrast to superfluidity in the three-dimensional

case, the effect of imbalance is also pronounced in the strong-coupling regime.

\\ ( http://arxiv.org/abs/0903.1931 , 521kb)

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arXiv:0903.1954

Date: Wed, 11 Mar 2009 11:58:52 GMT (227kb)

Title: Dynamics of formation and decay of coherence in a polariton condensate

Authors: E. del Valle, D. Sanvitto, A. Amo, F.P. Laussy, A. Andre, C. Tejedor

and L. Vina

Categories: cond-mat.mes-hall

\\

We study the dynamics of formation and decay of a condensate of microcavity

polaritons. We investigate the relationship between the number of particles,

the emission's linewidth and its degree of linear polarization which serves as

the order parameter. Tracking the condensate's formation, we show that, even

when interactions are negligible, coherence is not determined only by

occupation of the ground state. As a result of the competition between the

coherent and thermal fractions of the condensate, the highest coherence is

obtained some time after the particle number has reached its maximum.

\\ ( http://arxiv.org/abs/0903.1954 , 227kb)

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arXiv:0903.2017

Date: Wed, 11 Mar 2009 17:32:54 GMT (232kb)

Title: Quantum distillation: dynamical generation of low-entropy states of

strongly correlated fermions in an optical lattice

Authors: F. Heidrich-Meisner, S. R. Manmana, M. Rigol, A. Muramatsu, A. E.

Feiguin, E. Dagotto

Categories: cond-mat.str-el

Comments: 4 pages Revtex 4, 4 eps figures

\\

Correlations between particles can lead to subtle and sometimes

counterintuitive phenomena. We analyze one such case, occurring during the

sudden expansion of fermions in a lattice when the initial state has a strong

admixture of double occupancies. We promote the notion of quantum distillation:

during the expansion, and in the presence of strongly repulsive interactions,

tightly bound pairs group together, forming a nearly ideal band insulator,

which is metastable with a low entropy. We discuss how this effect could be

used for cooling purposes in experiments with two-component Fermi gases.

\\ ( http://arxiv.org/abs/0903.2017 , 232kb)

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arXiv:0903.1993

Date: Wed, 11 Mar 2009 16:04:47 GMT (328kb,D)

Title: Quantum breathing mode of trapped bosons and fermions at arbitrary

coupling

Authors: S. Bauch, K. Balzer, C. Henning, and M. Bonitz

Categories: quant-ph

\\

An analysis of the quantum breathing behavior of few-particle Coulomb systems

in one- and two-dimensional harmonic traps is presented. We report the

existence of \emph{two independent breathing modes} and present exact numerical

results for two particles at any coupling strength which smoothly connect the

two known limits of an \emph {ideal} quantum and a strongly coupled \emph

{classical} system. Substantial differences in the breathing frequency of

two-dimensional fermions and bosons are observed which may be used as a

sensitive experimental tool to probe confined interacting quantum systems.

\\ ( http://arxiv.org/abs/0903.1993 , 328kb)

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arXiv:0903.2111

Date: Thu, 12 Mar 2009 08:49:39 GMT (159kb)

Title: Critical Velocity in a Bose Gas in a Moving Optical Lattice at Finite

Temperatures

Authors: Emiko Arahata, Tetsuro Nikuni

Categories: cond-mat.other

Comments: 9 pages, 5 figures

\\

We study the critical velocity of a Bose-condensed gas in a moving

one-dimensional (1D) optical lattice potential at finite temperatures. Solving

the Gross-Pitaeavskii equation and the Bogoliubov equations, within the Popov

approximation, we calculate the Bogoliubov excitations with varying lattice

velocity. From the condition of the negative excitation energy, we determine

the critical velocity as a function of the lattice depth and the temperature.

We find that the critical velocity decreases rapidly with increasing the

temperature; this result is consistent with the experimental observations.

Moreover, the critical velocity shows a rapid decrease with increasing lattice

depth. This tendency is much more significant than in the previous works

ignoring the effect of thermal excitations in the radial direction.

\\ ( http://arxiv.org/abs/0903.2111 , 159kb)

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\\

arXiv:0903.2254

Date: Thu, 12 Mar 2009 19:39:51 GMT (498kb,D)

Title: Emergent superfluid crystals, frustration, and topologically defected

states in multimode cavity QED

Authors: Sarang Gopalakrishnan, Benjamin L. Lev, and Paul M. Goldbart

Categories: cond-mat.other

Comments: 8 pages, 3 figures

\\

We propose that condensed matter phenomena involving the spontaneous

emergence and dynamics of crystal lattices can be realized in the setting of

ultracold Bose-condensed atoms coupled to multimode cavities. Previously, it

was shown that in the case of a transversely pumped single-mode cavity, the

atoms self-organize at either the even or the odd antinodes of the cavity mode,

given sufficient pump intensity, and hence spontaneously break a discrete

translational symmetry. Here, we demonstrate that in multimode cavities the

self-organization brings the additional feature of continuous translational

symmetry breaking, via a variant of Brazovskii's transition, thus paving the

way for realizations of compliant lattices and associated phenomena, e.g.,

quantum melting, topological defects, frustration, glassiness, and even

supersolidity; such phenomena are absent in ultracold atomic systems when the

optical lattices are externally imposed. We apply a functional integral

approach to this many-body cavity QED system, which enables us, inter alia, to

calculate transition thresholds, explore fluctuations near this transition, and

determine how such fluctuations are manifest in the light emitted from the

cavity.

\\ ( http://arxiv.org/abs/0903.2254 , 498kb)

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arXiv:0903.2050

Date: Wed, 11 Mar 2009 20:03:16 GMT (214kb,D)

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

spin

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

Black, JM Geremia

Categories: quant-ph

Comments: 17 pages

\\

We argue that it is possible in principle to reduce the uncertainty of an

atomic magnetometer by double-passing a far-detuned laser field through the

atomic sample as it undergoes Larmor precession. Numerical simulations of the

quantum Fisher information suggest that, despite the lack of explicit

multi-body coupling terms in the system's magnetic Hamiltonian, the parameter

estimation uncertainty in such a physical setup scales better than the

conventional Heisenberg uncertainty limit over a specified but arbitrary range

of particle number N. Using the methods of quantum stochastic calculus and

filtering theory, we demonstrate numerically an explicit parameter estimator

(called a quantum particle filter) whose observed scaling follows that of our

calculated quantum Fisher information. Moreover, the quantum particle filter

quantitatively surpasses the uncertainty limit calculated from the quantum

Cramer-Rao inequality based on a magnetic coupling Hamiltonian with only

single-body operators. We also show that a quantum Kalman filter is

insufficient to obtain super-Heisenberg scaling, and present evidence that such

scaling necessitates going beyond the manifold of Gaussian atomic states.

\\ ( http://arxiv.org/abs/0903.2050 , 214kb)

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The replacements:

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arXiv:0708.2781

replaced with revised version Thu, 5 Mar 2009 07:12:43 GMT (28kb)

Title: Comment on "Laser cooling of rubidium atoms from background vapor in

diffuse light"

Authors: V.A. Kuz'menko

Categories: physics.gen-ph

Comments: 2 pages, 1 figure

\\ ( http://arxiv.org/abs/0708.2781 , 28kb)

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\\

arXiv:0903.0047

replaced with revised version Thu, 5 Mar 2009 14:01:24 GMT (24kb)

Title: Efficient atomization of cesium metal in solid helium by low energy (10

$\mu$J) femtosecond pulses

Authors: Mathieu Melich (LKB - Lhomond), Jacques Dupont-Roc (LKB - Lhomond),

Philippe Jacquier (LKB - Lhomond)

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

\\ ( http://arxiv.org/abs/0903.0047 , 24kb)

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arXiv:0811.1537

replaced with revised version Mon, 9 Mar 2009 10:10:34 GMT (1106kb)

Title: Multiband bosons in optical lattices

Authors: J. Larson, A. Collin, and J.-P. Martikainen

Categories: cond-mat.other quant-ph

Report-no: NORDITA-2008-50

Journal-ref: Phys. Rev. A 79, 033603 (2009)

\\ ( http://arxiv.org/abs/0811.1537 , 1106kb)

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arXiv:0804.1220

replaced with revised version Tue, 10 Mar 2009 05:54:25 GMT (9kb)

Title: A condition for the Bose-Einstein transition in the superfluid liquid

helium

Authors: V. N. Minasyan

Categories: cond-mat.supr-con

Comments: 8 pages

\\ ( http://arxiv.org/abs/0804.1220 , 9kb)

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arXiv:0805.0847

replaced with revised version Tue, 10 Mar 2009 01:09:20 GMT (501kb)

Title: Dynamics of rotating two-component Bose-Einstein Condensates

Authors: I. Corro, R.G. Scott, and A.M. Martin

Categories: cond-mat.other quant-ph

Comments: v4: more material added. 9 pages, 6 figures v5: figures fixed

\\ ( http://arxiv.org/abs/0805.0847 , 501kb)

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arXiv:0806.0039

replaced with revised version Tue, 10 Mar 2009 10:19:08 GMT (244kb)

Title: Ground state of low dimensional dipolar gases: linear and zigzag chains

Authors: G. E. Astrakharchik, Giovanna Morigi, Gabriele De Chiara, and J.

Boronat

Categories: cond-mat.other quant-ph

Journal-ref: Phys. Rev. A 78, 063622 (2008); Virtual Journal of Nanoscale

Science & Technology, vol. 19, Issue 2 (2009)

\\ ( http://arxiv.org/abs/0806.0039 , 244kb)

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arXiv:0807.5062

replaced with revised version Tue, 10 Mar 2009 06:21:12 GMT (51kb)

Title: Atom-atom correlations in colliding Bose-Einstein condensates

Authors: Magnus Ogren and K. V. Kheruntsyan

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

Comments: Minor corrections to the text; final published version

Journal-ref: Phys. Rev. A 79, 021606(R) (2009)

\\ ( http://arxiv.org/abs/0807.5062 , 51kb)

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arXiv:0812.4077

replaced with revised version Tue, 10 Mar 2009 04:19:49 GMT (26kb)

Title: Detection of valence bond order of ultracold atoms in optical lattices

by off-resonant scattering of cavity photons

Authors: Jinwu Ye, Jiangming Zhang, Wuming Liu, Keye Zhang, Yan Li and Weiping

Zhang

Categories: physics.atom-ph cond-mat.str-el physics.optics

Comments: 4+ \epsilon pages, 3 color figures, REVTEX

\\ ( http://arxiv.org/abs/0812.4077 , 26kb)

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arXiv:0810.0360

replaced with revised version Wed, 11 Mar 2009 08:02:00 GMT (75kb)

Title: Semilinear response for the heating rate of cold atoms in vibrating

traps

Authors: Alexander Stotland, Doron Cohen, Nir Davidson

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

Comments: 6 pages, 6 figures, improved version to be published in Europhysics

Letters

\\ ( http://arxiv.org/abs/0810.0360 , 75kb)

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arXiv:0812.1997

replaced with revised version Wed, 11 Mar 2009 08:45:34 GMT (117kb)

Title: Exploring dynamic localization with a Bose-Einstein condensate

Authors: Andre Eckardt, Martin Holthaus, Hans Lignier, Alessandro Zenesini,

Donatella Ciampini, Oliver Morsch, and Ennio Arimondo

Categories: cond-mat.other

Comments: 7 pages, 4 figures

Journal-ref: Phys. Rev. A 79, 013611 (2009)

DOI: 10.1103/PhysRevA.79.013611

\\ ( http://arxiv.org/abs/0812.1997 , 117kb)

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arXiv:0812.3403

replaced with revised version Tue, 10 Mar 2009 21:54:41 GMT (115kb)

Title: A geometrical approach to the dynamics of spinor condensates I:

Hydrodynamics

Authors: Ryan Barnett, Daniel Podolsky, Gil Refael

Categories: cond-mat.other cond-mat.str-el

Comments: 12 pages. First paper in two-part series

\\ ( http://arxiv.org/abs/0812.3403 , 115kb)

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arXiv:0808.2697

replaced with revised version Wed, 11 Mar 2009 00:53:54 GMT (52kb)

Title: Adiabatic approximation with exponential accuracy for many-body systems

and quantum computation

Authors: D.A. Lidar, A.T. Rezakhani, A. Hamma

Categories: quant-ph math-ph math.MP

Comments: 22 pages, 2 figures. Supersedes arXiv:0804.0604. v2: some

corrections, new remarks, and a new subsection on the adiabatic theorem for

open systems. v3: additional corrections

\\ ( http://arxiv.org/abs/0808.2697 , 52kb)

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arXiv:0807.1503

replaced with revised version Thu, 12 Mar 2009 03:21:15 GMT (513kb)

Title: Theory for superfluidity in a Bose system

Authors: Zhidong Hao

Categories: cond-mat.supr-con

Comments: 17 pages 12 figures; revised; and added quatitative description of

Hess-Fiarbank effect

\\ ( http://arxiv.org/abs/0807.1503 , 513kb)

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arXiv:0810.2089 (*cross-listing*)

replaced with revised version Thu, 12 Mar 2009 10:07:20 GMT (37kb)

Title: Can stochastic quantization evade the sign problem? -- the relativistic

Bose gas at finite chemical potential

Authors: Gert Aarts (Swansea University)

Categories: hep-lat cond-mat.other hep-ph nucl-th

Comments: 4 pages, 4 eps figures, v2: minor changes, outlook expanded,

references added, to appear in PRL

\\ ( http://arxiv.org/abs/0810.2089 , 37kb)

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arXiv:0810.5081

replaced with revised version Thu, 12 Mar 2009 09:24:55 GMT (28kb)

Title: Magnetic and Superfluid Transitions in the d=1 Spin-1 Boson Hubbard

Model

Authors: G.G. Batrouni, V.G. Rousseau, and R.T. Scalettar

Categories: cond-mat.other

Comments: Added results

\\ ( http://arxiv.org/abs/0810.5081 , 28kb)

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arXiv:0811.3316

replaced with revised version Thu, 12 Mar 2009 11:46:33 GMT (88kb)

Title: Bloch oscillations in one-dimensional spinor gas

Authors: D.M. Gangardt, A. Kamenev

Categories: cond-mat.stat-mech

Comments: 4 pages, 2 figures

Journal-ref: Phys. Rev. Lett. 102, 070402 (2009)

DOI: 10.1103/PhysRevLett.102.070402

\\ ( http://arxiv.org/abs/0811.3316 , 88kb)

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arXiv:0801.3255

replaced with revised version Thu, 12 Mar 2009 08:02:01 GMT (580kb,D)

Title: A simple integrated single-atom detector

Authors: Marco Wilzbach, Dennis Heine, S\"onke Groth, Xiyuan Liu, Thomas Raub,

Bj\"orn Hessmo, J\"org Schmiedmayer

Categories: physics.atom-ph physics.optics

Comments: 3 pages, 3 figures

Journal-ref: Optics Letters, Vol. 34, page 259 (2009)

DOI: 10.1364/OL.34.000259

\\ ( http://arxiv.org/abs/0801.3255 , 580kb)

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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 =========================================================================Received on Thu May 21 2009 - 15:50:53 EST

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