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

Date: Wed, 1 Sep 2010 09:57:15 +1000

Date: Wed, 1 Sep 2010 09:57:15 +1000

Dear subscribers,

This week's selection was compiled by Simon Haine, and contains 42 new abstracts

and 8 replacements.

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arXiv:1006.0739

Date: Thu, 3 Jun 2010 20:29:57 GMT (311kb,D)

Title: Realization of an Excited, Strongly-Correlated Quantum Gas Phase

Authors: Elmar Haller, Mattias Gustavsson, Manfred J. Mark, Johann G. Danzl,

Russell Hart, Guido Pupillo, Hanns-Christoph N\"agerl

Categories: cond-mat.quant-gas

Journal-ref: Science 325, 1224 (2009)

\\

Ultracold atomic physics offers myriad possibilities to study strongly

correlated many-body systems in lower dimensions. Typically, only ground state

phases are accessible. Using a tunable quantum gas of bosonic cesium atoms, we

realize and control in one dimensional geometry a highly excited quantum phase

that is stabilized in the presence of attractive interactions by maintaining

and strengthening quantum correlations across a confinement-induced resonance.

We diagnose the crossover from repulsive to attractive interactions in terms of

the stiffness and the energy of the system. Our results open up the

experimental study of metastable excited many-body phases with strong

correlations and their dynamical properties.

\\ ( http://arxiv.org/abs/1006.0739 , 311kb)

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arXiv:1006.0742

Date: Thu, 3 Jun 2010 20:54:32 GMT (4249kb)

Title: Dipole blockade in a cold Rydberg atomic sample

Authors: Daniel Comparat and Pierre Pillet

Categories: physics.atom-ph quant-ph

Comments: Similar (without Appendix) article have been published in JOSA B, 27,

A208 (2010)

Journal-ref: JOSA B, Vol. 27, Issue 6, pp. A208-A232 (2010)

DOI: 10.1364/JOSAB.27.00A208

\\

We review here the studies performed about interactions in an assembly of

cold Rydberg atoms. We focus more specially the review on the dipole-dipole

interactions and on the effect of the dipole blockade in the laser Rydberg

excitation, which offers attractive possibilities for quantum engineering. We

present first the various interactions between Rydberg atoms. The laser Rydberg

excitation of such an assembly is then described with the introduction of the

dipole blockade phenomenon. We report recent experiments performed in this

subject by starting with the case of a pair of atoms allowing the entanglement

of the wave-functions of the atoms and opening a fascinating way for the

realization of quantum bits and quantum gates. We consider then several works

on the blockade effect in a large assembly of atoms for three different

configurations: blockade through electric-field induced dipole, through

F\"orster resonance and in van der Waals interaction. The properties of

coherence and cooperativity are analyzed. Finally, we treat the role of

dipole-dipole interactions between Rydberg atoms responsible for Penning

ionization. The perturbation of the dipole blockade by ions and the evolution

of the Rydberg towards an ultracold plasma are discussed.

\\ ( http://arxiv.org/abs/1006.0742 , 4249kb)

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arXiv:1006.0754

Date: Thu, 3 Jun 2010 23:06:41 GMT (2758kb,D)

Title: Probing the Superfluid to Mott Insulator Transition at the Single Atom

Level

Authors: Waseem S. Bakr, Amy Peng, M. Eric Tai, Ruichao Ma, Jonathan Simon,

Jonathon I. Gillen, Simon Foelling, Lode Pollet, Markus Greiner

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

\\

Quantum gases in optical lattices offer an opportunity to experimentally

realize and explore condensed matter models in a clean, tunable system. We

investigate the Bose-Hubbard model on a microscopic level using single

atom-single lattice site imaging; our technique enables space- and

time-resolved characterization of the number statistics across the

superfluid-Mott insulator quantum phase transition. Site-resolved probing of

fluctuations provides us with a sensitive local thermometer, allows us to

identify microscopic heterostructures of low entropy Mott domains, and enables

us to measure local quantum dynamics, revealing surprisingly fast transition

timescales. Our results may serve as a benchmark for theoretical studies of

quantum dynamics, and may guide the engineering of low entropy phases in a

lattice.

\\ ( http://arxiv.org/abs/1006.0754 , 2758kb)

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arXiv:1006.0762

Date: Fri, 4 Jun 2010 00:56:15 GMT (4272kb)

Title: Time-reversal symmetry breaking in circuit-QED based photon lattices

Authors: Jens Koch, Andrew A. Houck, Karyn Le Hur, S. M. Girvin

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

Comments: 19 pages, 13 figures, 2 tables

\\

Breaking time-reversal symmetry is a prerequisite for accessing certain

interesting many-body states such as fractional quantum Hall states. For

polaritons, charge neutrality prevents magnetic fields from providing a direct

symmetry breaking mechanism and similar to the situation in ultracold atomic

gases, an effective magnetic field has to be synthesized. We show that in the

circuit QED architecture, this can be achieved by inserting simple

superconducting circuits into the resonator junctions. In the presence of such

coupling elements, constant parallel magnetic and electric fields suffice to

break time-reversal symmetry. We support these theoretical predictions with

numerical simulations for realistic sample parameters, specify general

conditions under which time-reversal is broken, and discuss the application to

chiral Fock state transfer, an on-chip circulator, and tunable band structure

for the Kagome lattice.

\\ ( http://arxiv.org/abs/1006.0762 , 4272kb)

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arXiv:1006.0769

Date: Fri, 4 Jun 2010 02:32:08 GMT (306kb)

Title: Energy spectrum of harmonically trapped two-component Fermi gases:

Three- and Four-Particle Problem

Authors: K. M. Daily and D. Blume

Categories: cond-mat.quant-gas

Comments: 11 figures

Journal-ref: Phys. Rev. A. 81, 053615 (2010)

\\

Trapped two-component Fermi gases allow for the investigation of the

so-called BCS-BEC crossover by tuning the interspecies atom-atom $s$-wave

scattering length scattering $a^{(aa)}$ from attractive to repulsive, including

vanishing and infinitely large values. Here, we numerically determine the

energy spectrum of the equal-mass spin-balanced four-fermion system---the

smallest few-particle system that exhibits BCS-BEC crossover-like behavior---as

a function of $a^{(aa)}$ using the stochastic variational approach. For

comparative purposes, we also treat the two- and three-particle systems. States

with vanishing and finite total angular momentum as well as with natural and

unnatural parity are considered. In addition, the energy spectrum of

weakly-attractive and weakly-repulsive gases is characterized by employing a

perturbative framework that utilizes hyperspherical coordinates. The

hyperspherical coordinate approach allows for the straightforward assignment of

quantum numbers and furthermore provides great insights into the

strongly-interacting unitary regime.

\\ ( http://arxiv.org/abs/1006.0769 , 306kb)

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arXiv:1006.0854

Date: Fri, 4 Jun 2010 10:40:53 GMT (100kb)

Title: Collapse dynamics of a ${}^{176}\textrm{Yb}\,$-${}^{174}\textrm{Yb}$

Bose-Einstein condensate

Authors: G. K. Chaudhary and R. Ramakumar

Categories: cond-mat.quant-gas

Comments: 6 pages, 5 figures

Journal-ref: Phys. Rev. A 81, 063603 (2010)

DOI: 10.1103/PhysRevA.81.063603

\\

In this paper, we present a theoretical study of a two-component

Bose-Einstein condensate composed of Ytterbium (Yb) isotopes in a three

dimensional anisotropic harmonic potential. The condensate consists of a

mixture of ${}^{176}\textrm{Yb}$ atoms which have a negative s-wave scattering

length and ${}^{174}\textrm{Yb}$ atoms having a positive s-wave scattering

length. We study the ground state as well as dynamic properties of this

two-component condensate. Due to the attractive interactions between

${}^{176}\textrm{Yb}$ atoms, the condensate of ${}^{176}\textrm{Yb}$ undergo a

collapse when the particle number exceed a critical value. The critical number

and the collapse dynamics are modified due to the presence of

${}^{174}\textrm{Yb}$ atoms. We use coupled two-component Gross-Pitaevskii

equations to study the collapse dynamics. The theoretical results obtained are

in reasonable agreement with the experimental results of Fukuhara {\em et al.}

[PRA{\bf 79}, 021601(R) (2009)].

\\ ( http://arxiv.org/abs/1006.0854 , 100kb)

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arXiv:1006.0905 (*cross-listing*)

Date: Fri, 4 Jun 2010 14:29:00 GMT (199kb)

Title: When is it easier for a quantum particle to tunnel through than to fly

above a barrier?

Authors: Denys I. Bondar, Wing-Ki Liu, and Misha Yu. Ivanov

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

Comments: 8 pages and 6 figures

\\

We present a class of 2D systems which shows a counterintuitive property that

contradicts a semi classical intuition: a 2D quantum particle "prefers"

tunnelling through a barrier rather than travelling above it. Viewing the one

particle 2D system as the system of two 1D particles, it is demonstrated that

this effect occurs due to a specific symmetry of the barrier that forces

excitations of the interparticle degree of freedom that, in turn, leads to the

appearance of an effective potential barrier even though there is no "real"

barrier. This phenomenon cannot exist in 1D.

\\ ( http://arxiv.org/abs/1006.0905 , 199kb)

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arXiv:1006.0917

Date: Fri, 4 Jun 2010 15:06:03 GMT (217kb)

Title: Measurement of the atom number distribution in an optical tweezer using

single photon counting

Authors: A. Fuhrmanek, Y.R.P. Sortais, P. Grangier and A. Browaeys

Categories: cond-mat.quant-gas

Comments: 6 pages, 5 figures

\\

We demonstrate in this paper a method to reconstruct the atom number

distribution of a cloud containing a few tens of cold atoms. The atoms are

first loaded from a magneto-optical trap into a microscopic optical dipole trap

and then released in a resonant light probe where they undergo a Brownian

motion and scatter photons. We count the number of photon events detected on an

image intensifier. Using the response of our detection system to a single atom

as a calibration, we extract the atom number distribution when the trap is

loaded with more than one atom. The atom number distribution is found to be

compatible with a Poisson distribution.

\\ ( http://arxiv.org/abs/1006.0917 , 217kb)

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arXiv:1006.0924

Date: Fri, 4 Jun 2010 15:43:12 GMT (1083kb,D)

Title: Structure and consequences of vortex-core states in p-wave superfluids

Authors: G. Moller, N. R. Cooper, V. Gurarie

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

Comments: 18 pages, 10 figures

\\

It is now well established that in two-dimensional chiral p-wave paired

superfluids, the vortices carry zero-energy modes which obey non-abelian

exchange statistics and can potentially be used for topological quantum

computation. In such superfluids there may also exist other excitations below

the bulk gap inside the cores of vortices. We study the properties of these

subgap states, and argue that their presence affects the topological protection

of the zero modes. In conventional superconductors where the chemical potential

is of the order of the Fermi energy of a non-interacting Fermi gas, there is a

large number of subgap states and the mini-gap towards the lowest of these

states is a small fraction of the Fermi energy. It is therefore difficult to

cool the system to below the mini-gap and at experimentally available

temperatures, transitions between the subgap states, including the zero modes,

will occur and can alter the quantum states of the zero-modes. We show that

compound qubits involving the zero-modes and the parity of the occupation

number of the subgap states on each vortex are still well defined. However,

practical schemes taking into account all subgap states would nonetheless be

difficult to achieve. We propose to avoid this difficulty by working in the

regime of small chemical potential mu, near the transition to a strongly paired

phase, where the number of subgap states is reduced. We develop the theory to

describe this regime of strong pairing interactions and we show how the subgap

states are ultimately absorbed into the bulk gap. Since the bulk gap vanishes

as mu -> 0 there is an optimum value mu_c which maximises the combined gap. We

propose cold atomic gases as candidate systems where the regime of strong

interactions can be explored, and explicitly evaluate mu_c in a Feshbach

resonant K-40 gas.

\\ ( http://arxiv.org/abs/1006.0924 , 1083kb)

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arXiv:1006.0928 (*cross-listing*)

Date: Fri, 4 Jun 2010 15:45:39 GMT (28kb)

Title: Critical mass and the dependency of research quality on group size

Authors: Ralph Kenna, Bertrand Berche

Categories: physics.soc-ph cond-mat.stat-mech

Comments: 14 pages, 6 figures consisting of 16 panels

\\

Academic research groups are treated as complex systems and their cooperative

behaviour is analysed from a mathematical and statistical viewpoint. Contrary

to the naive expectation that the quality of a research group is simply given

by the mean calibre of its individual scientists, we show that intra-group

interactions play a dominant role. Our model manifests phenomena akin to phase

transitions which are brought about by these interactions, and which facilitate

the quantification of the notion of critical mass for research groups. We

present these critical masses for many academic areas. A consequence of our

analysis is that overall research performance of a given discipline is improved

by supporting medium-sized groups over large ones, while small groups must

strive to achieve critical mass.

\\ ( http://arxiv.org/abs/1006.0928 , 28kb)

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arXiv:1006.0943

Date: Fri, 4 Jun 2010 17:06:26 GMT (2498kb,D)

Title: Transfer of BECs through discrete breathers in an optical lattice

Authors: Holger Hennig, J\'er\^ome Dorignac, David K. Campbell

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

Comments: 8 pages, 5 figures

\\

We study the stability of a stationary discrete breather (DB) on a nonlinear

trimer in the framework of the discrete nonlinear Schr\"odinger equation

(DNLS). In previous theoretical investigations of the dynamics of Bose-Einstein

condensates in leaking optical lattices, collisions between a DB and a lattice

excitation, e.g. a moving breather (MB) or phonon, were studied. These

collisions lead to the transmission of a fraction of the incident (atomic) norm

of the MB through the DB, while the DB can be shifted in the direction of the

incident lattice excitation. Here we show that there exists a total energy

threshold of the trimer, above which the lattice excitation can trigger the

destabilization of the DB and that this is the mechanism leading to the

movement of the DB. Furthermore, we give an analytic estimate of upper bound to

the norm that is transmitted through the DB. Our analysis explains the results

of the earlier numerical studies and may help to clarify functional operations

with BECs in optical lattices such as blocking and filtering coherent (atomic)

beams.

\\ ( http://arxiv.org/abs/1006.0943 , 2498kb)

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arXiv:1006.0966

Date: Fri, 4 Jun 2010 19:08:48 GMT (830kb)

Title: Cold Fermi-gas with long range interaction in a harmonic trap

Authors: M. Kulkarni, A. G. Abanov

Categories: cond-mat.quant-gas cond-mat.str-el hep-th math-ph math.MP

Comments: 11 pages, 5 figures

\\

We study equilibrium density and spin density profiles for a model of cold

one-dimensional spin 1/2 fermions interacting via inverse square interaction

and exchange in an external harmonic trap. This model is the well-known

spin-Calogero model (sCM) and its fully nonlinear collective field theory

description (up to gradients) is known[1]. We extend the field theory

description to the presence of an external harmonic trap and obtain analytic

results for statics and dynamics of the system. For instance, we find how the

equilibrium density profile changes upon tuning the interaction strength. The

results we obtain for equilibrium configurations are very similar to the ones

obtained recently by Ma and Yang[2] for a different model - one-dimensional

fermions with contact interactions. Our main approximation is the neglect of

the terms of higher order in spatial derivatives in equations of motion -

gradientless approximation[1]. Within this approximation the hydrodynamic

equations of motion can be written as a set of decoupled forced Riemann-Hopf

equations for the dressed Fermi momenta of the model. This enables us to write

analytical solutions for the dynamics of spin and charge. We describe the time

evolution of the charge density when an initial non-equilibrium profile is

created by cooling the gas with an additional potential in place and then

suddenly removing the potential. We present our results as a simple

"single-particle" evolution in the phase-space reminiscing a similar

description of the dynamics of non-interacting one-dimensional fermions.

\\ ( http://arxiv.org/abs/1006.0966 , 830kb)

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arXiv:1006.0969

Date: Fri, 4 Jun 2010 19:19:16 GMT (910kb)

Title: Techniques to measure quantum criticality in cold atoms

Authors: Kaden R. A. Hazzard and Erich J. Mueller

Categories: cond-mat.quant-gas cond-mat.stat-mech cond-mat.str-el quant-ph

Comments: 12 double spaced pages (main text), 12 double spaced pages

(supplementary information), 4 figures (10 panels)

\\

Attempts to understand zero temperature phase transitions have forced

physicists to consider a regime where the standard paradigms of condensed

matter physics break down [1-4]. These quantum critical systems lack a simple

description in terms of weakly interacting quasiparticles, but over the past 20

years physicists have gained deep insights into their properties. Most

dramatically, theory predicts that universal scaling relationships describe

their finite temperature thermodynamics up to remarkably high temperatures.

Unfortunately, these universal functions are hard to calculate: for example

there are no reliable general techniques [4,5] to calculate the scaling

functions for dynamics. Viewing a cold atom experiment as a quantum simulator

[6], we show how to extract universal scaling functions from (non-universal)

atomic density profiles or spectroscopic measurements. Such experiments can

resolve important open questions about the Mott-Metal crossover [7,8] and the

dynamics of the finite density O(2) rotor model [1,9], with direct impact on

theories of, for example, high temperature superconducting cuprates [10,11],

heavy fermion materials [12], and graphene [13].

\\ ( http://arxiv.org/abs/1006.0969 , 910kb)

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arXiv:1006.1072

Date: Sat, 5 Jun 2010 21:49:52 GMT (19kb)

Title: An Example of Quantum Anomaly in the Physics of Ultra-Cold Gases

Authors: Maxim Olshanii, H\'el\`ene Perrin, Vincent Lorent

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

Comments: 5 pages, 2 figures

\\

In this article, we propose an experimental scheme for observation of a

quantum anomaly---quantum-mechanical symmetry breaking---in a two-dimensional

harmonically trapped Bose gas. The anomaly manifests itself in a shift of the

monopole excitation frequency away from the value dictated by the

Pitaevskii-Rosch dynamical symmetry [L. P. Pitaevskii and A. Rosch, Phys. Rev.

A, 55, R853 (1997)]. While the corresponding classical Gross-Pitaevskii

equation and the derived from it hydrodynamic equations do exhibit this

symmetry, it is---as we show in our paper---violated under quantization. The

resulting frequency shift is of the order of 1% of the carrier, well in reach

for modern experimental techniques. We propose using the dipole oscillations as

a frequency gauge.

\\ ( http://arxiv.org/abs/1006.1072 , 19kb)

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arXiv:1006.1131

Date: Sun, 6 Jun 2010 19:11:39 GMT (2434kb)

Title: Double-degenerate Bose-Fermi mixture of strontium

Authors: Meng Khoon Tey, Simon Stellmer, Rudolf Grimm, Florian Schreck

Categories: cond-mat.quant-gas

Comments: 5 pages, 5 figures

\\

We report on the attainment of a spin-polarized Fermi sea of 87-Sr in thermal

contact with a Bose-Einstein condensate (BEC) of 84-Sr. Interisotope collisions

thermalize the fermions with the bosons during evaporative cooling. A

degeneracy of T/T_F=0.30(5) is reached with 2x10^4 87-Sr atoms together with an

almost pure 84-Sr BEC of 10^5 atoms.

\\ ( http://arxiv.org/abs/1006.1131 , 2434kb)

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arXiv:1006.1174

Date: Mon, 7 Jun 2010 05:54:57 GMT (1053kb,D)

Title: Signature of Quantum Criticality in the Density Profiles of Cold Atom

Systems

Authors: Qi Zhou and Tin-Lun Ho

Categories: cond-mat.quant-gas

Comments: 4 pages, 5 figures

\\

In recent years, there is considerable experimental effort using cold atoms

to study strongly correlated many-body systems. One class of phenomena of

particularly interests is quantum critical (QC) phenomena. While prevalent in

many materials, these phenomena are notoriously difficult theoretical problems

due to the vanishing of energy scales in QC region. So far, there are no

systematic ways to deduce QC behavior of bulk systems from the data of trapped

atomic gases. Here, we present a simple algorithm to use the experimental

density profile to determine the T=0 phase boundary of bulk systems, as well as

the scaling functions in QC regime. We also present another scheme for removing

finite size effects of the trap. We demonstrate the validity of our schemes

using exactly soluble models.

\\ ( http://arxiv.org/abs/1006.1174 , 1053kb)

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arXiv:1006.1269

Date: Mon, 7 Jun 2010 15:02:55 GMT (482kb)

Title: Incompressible states of a two-component Fermi gas in a double-well

optical lattice

Authors: Fran\ccois Cr\'epin, Roberta Citro and Pascal Simon

Categories: cond-mat.quant-gas

Comments: 10 pages, 7 figures. Accepted for publication in PRA

\\

We propose a scheme to investigate the effect of frustration on the magnetic

phase transitions of cold atoms confined in an optical lattice. We also

demonstrate how to get two-leg spin ladders with frustrated spin-exchange

coupling which display a phase transition from a spin liquid to a fully

incompressible state. Various experimental quantities are further analyzed for

describing this new phase.

\\ ( http://arxiv.org/abs/1006.1269 , 482kb)

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arXiv:1006.1295

Date: Mon, 7 Jun 2010 16:46:27 GMT (745kb)

Title: Observation of a red-blue detuning asymmetry in matter-wave

superradiance

Authors: L.Deng, E. W. Hagley, Qiang Cao, Xiaorui Wang, Xinyu Luo, Ruquan Wang,

Fan Yang, Xiaoji Zhou, Xuzong Chen, M. G. Payne and Mingsheng Zhan

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

Comments: The original version of this manuscript was first submitted in early

March, 2010 to Physical Review A Rapid Communications

\\

We show the first experimental observations of matter-wave superradiance

using blue-detuned light, and demonstrate a pump-laser detuning asymmetry in

the collective atomic recoil motion. In contrast to all previous theoretical

treatments, which predict that the process should be symmetric with respect to

the sign of the pump-laser detuning, we find that for sufficiently high

condensate densities the symmetry is broken. However, in the limit of a dilute

atomic gas the symmetry is restored. With high atomic densities and a

red-detuned pump laser, the usual distinctive multi-order matter-wave

scattering pattern is clearly visible, whereas with blue-detuned light the

collective atom recoil motion is strongly suppressed.

\\ ( http://arxiv.org/abs/1006.1295 , 745kb)

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arXiv:1006.1336 (*cross-listing*)

Date: Mon, 7 Jun 2010 19:14:22 GMT (32kb)

Title: Generation and detection of NOON states in superconducting circuits

Authors: Seth T. Merkel and Frank K. Wilhelm

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

Comments: 15 pages and 3 figures

\\

NOON states, states between two modes of light of the form

$|N,0\rangle+e^{i\phi}|0,N\rangle$ allow for super-resolution interformetry. We

show how NOON states can be efficiently produced in circuit quntum

electrodynamics using superconducting phase qubits and resonators. We propose a

protocol where only one interaction between the two modes is required, creating

all the necessary entanglement at the start of the procedure. This protocol

makes active use of the first three states of the phase qubits. Additionally,

we show how to efficiently verify the success of such an experiment, even for

large NOON states, using randomly sampled measurements and semidefinite

programming techniques.

\\ ( http://arxiv.org/abs/1006.1336 , 32kb)

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arXiv:1006.1392

Date: Mon, 7 Jun 2010 22:39:24 GMT (52kb)

Title: Speed of sound in a superfluid Fermi gas in an optical lattice

Authors: Z. G. Koinov

Categories: cond-mat.str-el

\\

A system of equal mixture of $^6Li$ atomic Fermi gas of two hyperfine states

loaded into a cubic three-dimensional optical lattice is studied assuming a

negative scattering length (BCS side of the Feshbach resonance). When the

interaction is attractive, fermionic atoms can pair and form a superfluid. The

dispersion of the phonon-like mode and the speed of sound in the

long-wavelength limit are obtained by solving the Bethe-Salpeter equations for

the collective modes of the attractive Hubbard Hamiltonian.

\\ ( http://arxiv.org/abs/1006.1392 , 52kb)

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arXiv:1006.1438

Date: Tue, 8 Jun 2010 01:44:53 GMT (90kb,D)

Title: Semiclassical dynamics of quasi-one-dimensional, attractive

Bose-Einstein condensates

Authors: Alexander Tovbis and Mark A. Hoefer

Categories: cond-mat.quant-gas

Comments: 8 pages, 2 figures

\\

The strongly interacting regime for attractive Bose-Einstein condensates

(BECs) tightly confined in an extended cylindrical trap is studied. For

appropriately prepared BECs, the ensuing dynamics are found to be governed by

the one-dimensional focusing Nonlinear Schr\"{o}dinger equation (NLS) in the

semiclassical (small dispersion) regime. In spite of the modulational

instability of this regime, rigorous results on the strong asymptotics of the

semiclassical limiting solutions were obtained recently. Using these results,

"implosion" and "explosion" events are predicted whereby an initial hump

focuses into a sharp spike which then expands into rapid oscillations.

Seemingly related behavior has been observed in three-dimensional experiments

and models, where the supercritical NLS equation is known to admit a blow-up

singularity (collapse). The dynamical regimes studied here, however, are not

predicted to undergo collapse. Instead, distinct, ordered structures, appearing

after the "implosion", yield new observables that may be experimentally

accessible.

\\ ( http://arxiv.org/abs/1006.1438 , 90kb)

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arXiv:1006.1495

Date: Tue, 8 Jun 2010 09:22:19 GMT (64kb)

Title: Fast optimal transition between two equilibrium states

Authors: Jean-Fran\ccois Schaff, Xiao-Li Song, Patrizia Vignolo, and Guillaume

Labeyrie

Categories: cond-mat.quant-gas

Comments: 5 pages, 4 figures

\\

We present the first experimental demonstration of a technique based on

invariants of motion for a time-dependent Hamiltonian, allowing a fast

transition to a final equilibrium state identical to that obtain through a

perfectly adiabatic transformation. This method is applied to the fast

decompression of an ultracold cloud of $^{87}$Rb atoms held in a harmonic

magnetic trap, in the presence of gravity. Using an optimal frequency

trajectory, we are able to decompress the trap by a factor of 15 within 35 ms

with a strong suppression of the sloshing/breathing hybrid modes induced by the

large vertical displacement and curvature reduction of the trap. When compared

to a standard linear decompression, we achieve a gain of a factor 37 on the

transition time.

\\ ( http://arxiv.org/abs/1006.1495 , 64kb)

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arXiv:1006.1554

Date: Tue, 8 Jun 2010 13:32:34 GMT (595kb)

Title: Designing Zeeman slower for strontium atoms - towards optical atomic

clock

Authors: Marcin Bober, Jerzy Zachorowski, Wojciech Gawlik

Categories: physics.atom-ph

\\

We report on design and construction of a Zeeman slower for strontium atoms

which will be used in an optical atomic clock experiment. The paper describes

briefly required specifications of the device, possible solutions, and

concentrates on the chosen design. The magnetic field produced by the built

Zeeman slower has been measured and compared with the simulations. The system

consisting of an oven and Zeeman slower are designed to produce an atomic beam

of 10-12 s-1 flux and final velocity of ~30 m/s.

\\ ( http://arxiv.org/abs/1006.1554 , 595kb)

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arXiv:1006.1685

Date: Wed, 9 Jun 2010 02:25:54 GMT (35kb)

Title: Mott Transitions of Three-Component Fermionic Atoms with Repulsive

Interaction in Optical Lattices

Authors: Kensuke Inaba, Shin-ya Miyatake and Sei-ichiro Suga

Categories: cond-mat.quant-gas

Comments: 5 pages, 4 figures

\\

We investigate the Mott transitions of three-component (colors) repulsive

fermionic atoms in optical lattices using the dynamical mean field theory. We

find that for SU(3) symmetry breaking interactions the Mott transition occurs

at incommensurate half filling. As a result, a characteristic Mott insulating

state appears, where paired atoms with two different colors and atoms with the

third color are localized at different sites. We also find another Mott state

where atoms with two different colors are localized at different sites and

atoms with the third color remain itinerant. We demonstrate that these exotic

Mott phases can be detected by experimental double occupancy observations.

\\ ( http://arxiv.org/abs/1006.1685 , 35kb)

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arXiv:1006.1833 (*cross-listing*)

Date: Wed, 9 Jun 2010 15:28:09 GMT (1348kb)

Title: L\'evy-Schr\"odinger wave packets

Authors: Nicola Cufaro Petroni

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

Comments: 62 pages, 13 figures

Report-no: Rapporto n. 11/2010 - Dpt. of Mathematics, Bari University

MSC-class: 60G51 Processes with independent increments, L\'evy processes 81P20

Stochastic mechanics

\\

We analyze the time-dependent solutions of the pseudo-differential

L\'evy-Schr\"odinger wave equation in the free (force-less) case, and we

compare them with the associated L\'evy processes. We first list the principal

laws used to describe the time evolutions of both L\'evy process densities and

L\'evy-Schr\"odinger wave packets. To have self-adjoint generators and unitary

evolutions we will consider only absolutely continuous, infinitely divisible

L\'evy noises with laws symmetric under change of sign of the independent

variable. We then show a few examples of the characteristic behavior of the

L\'evy-Schr\"odinger wave packets, and in particular of the bi-modality arising

in their evolutions: a feature at variance with the typical diffusive

uni-modality of the L\'evy process densities.

\\ ( http://arxiv.org/abs/1006.1833 , 1348kb)

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\\

arXiv:1006.1856 (*cross-listing*)

Date: Wed, 9 Jun 2010 16:55:31 GMT (52kb)

Title: A study of Quantum Correlations in Open Quantum Systems

Authors: Indranil Chakrabarty, Subhashish Banerjee, Nana Siddharth

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

Comments: 12 pages, 6 figures

\\

In this work, we study quantum correlations in mixed states. The states

studied are modelled by a two-qubit system interacting with its environment via

a quantum nondemolition (purely dephasing) as well as dissipative type of

interaction. The entanglement dynamics of this two qubit system is analyzed and

the existence of entangled states which do not violate Bell's inequality, but

can still be useful as a potential resource for teleportation are reported. In

addition, a comparative study of various measures of quantum correlations, like

Concurrence, Bell's inequality, Discord and Teleportation fidelity, is made on

these states, generated by the above evolutions. Interestingly, examples are

found, of states, where entanglement is vanishing, but discord is

non-vanishing, bringing out the fact that entanglement is a subset of quantum

correlations.

\\ ( http://arxiv.org/abs/1006.1856 , 52kb)

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\\

arXiv:1006.1884

Date: Wed, 9 Jun 2010 19:31:20 GMT (1260kb,D)

Title: Vortices in quantum droplets: Analogies between boson and fermion

systems

Authors: H. Saarikoski, S.M. Reimann, A. Harju, M. Manninen

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

Comments: Review article, 53 pages, 53 figures

\\

The main theme of this review is the many-body physics of vortices in quantum

droplets of bosons or fermions, in the limit of small particle numbers. Systems

of interest include cold atoms in traps as well as electrons confined in

quantum dots. When set to rotate, these in principle very different quantum

systems show remarkable analogies. The topics reviewed include the structure of

the finite rotating many-body state, universality of vortex formation and

localization of vortices in both bosonic and fermionic systems, and the

emergence of particle-vortex composites in the quantum Hall regime. An overview

of the computational many-body techniques sets focus on the configuration

interaction and density-functional methods. Studies of quantum droplets with

one or several particle components, where vortices as well as coreless vortices

may occur, are reviewed, and theoretical as well as experimental challenges are

discussed.

\\ ( http://arxiv.org/abs/1006.1884 , 1260kb)

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\\

arXiv:1006.1971

Date: Thu, 10 Jun 2010 07:58:42 GMT (273kb)

Title: Hybrid Quantum System of a Nanofiber Mode Coupled to Two Chains of

Optically Trapped Atoms

Authors: Hashem Zoubi, and Helmut Ritsch

Categories: quant-ph

Comments: 9 pages, 9 figures

\\

A tapered optical nanofiber simultaneously used to trap and optically

interface of cold atoms through evanescent fields constitutes a new and well

controllable hybrid quantum system. The atoms are trapped in two parallel 1D

optical lattices generated by suitable far blue and red detuned evanescent

field modes very close to opposite sides of the nanofiber surface. Collective

electronic excitations (excitons) of each of the optical lattices are

resonantly coupled to the second lattice forming symmetric and antisymmetric

common excitons. In contrast to the inverse cube dependence of the individual

atomic dipole-dipole interaction, we analytically find an exponentially

decaying coupling strength with distance between the lattices. The resulting

symmetric (bright) excitons strongly interact with the resonant nanofiber

photons to form fiber polaritons, which can be observed through linear optical

spectra. For large enough wave vectors the polariton decay rate to free space

is strongly reduced, which should render this system ideal for the realization

of long range quantum communication between atomic ensembles.

\\ ( http://arxiv.org/abs/1006.1971 , 273kb)

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\\

arXiv:1006.1978 (*cross-listing*)

Date: Thu, 10 Jun 2010 08:39:26 GMT (35kb)

Title: Disordered quantum walk-induced localization of a Bose-Einstein

condensate

Authors: C. M. Chandrashekar

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

Comments: 5 pages, 4 figures

\\

We present a new approach to Anderson localization in one-dimensional lattice

under the influence of disordered quantum coin operation in the quantum walk

evolution. We introduce a discrete-time quantum walk model in which

interference effect modified to diffuse or localize the probability

distribution by assigning different set of random coin parameter to each step

of the walk, respectively. Spatial localization of the particle/state is

explained by comparing the variance of the probability distribution of the

quantum walk in position space using disordered coin operation to that of the

walk using an identical coin operation for each step. Due to the high degree of

control over quantum coin operation and most of the system parameters,

ultracold atoms in optical lattice offer opportunities to implement disordered

quantum walk which is unitary and induce localization. Here we use a

Bose-Einstein condensate which can be evolved to the superposition of its

internal states in optical lattice to study Anderson localization. This

approach can be adopted to any other physical system in which controlled

disordered quantum walk can be implemented.

\\ ( http://arxiv.org/abs/1006.1978 , 35kb)

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\\

arXiv:1006.2017

Date: Thu, 10 Jun 2010 12:35:25 GMT (44kb,D)

Title: Topological entanglement entropy relations for multi phase systems with

interfaces

Authors: F. A. Bais and J. K. Slingerland

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

Comments: 4 pages, 3 figures, 2 tables, revtex

\\

We study the change in topological entanglement entropy that occurs when a

two-dimensional system in a topologically ordered phase undergoes a transition

to another such phase due to the formation of a Bose condensate. We also

consider the topological entanglement entropy of systems with domains in

different topological phases, and of phase boundaries between these domains. We

calculate the topological entropy of these interfaces and derive two

fundamental relations between the interface topological entropy and the bulk

topological entropies on both sides of the interface.

\\ ( http://arxiv.org/abs/1006.2017 , 44kb)

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\\

arXiv:1006.2042

Date: Thu, 10 Jun 2010 14:17:43 GMT (196kb)

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

\\

We calculate the effect of interactions on the expansion of ultracold atoms

from a single site of an optical lattice. We use these results to predict how

interactions influence the interference pattern observed in a time of flight

experiment. We find that for typical interaction strengths their influence is

negligible, yet that they reduce visibility near a scattering resonance.

\\ ( http://arxiv.org/abs/1006.2042 , 196kb)

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\\

arXiv:1006.2072

Date: Thu, 10 Jun 2010 16:03:58 GMT (66kb)

Title: Time-Reversal-Breaking and $d$-Wave Superfluidity of Ultracold Dipolar

Fermions in Optical Lattices

Authors: Li Han and C. A. R. S\'a de Melo

Categories: cond-mat.quant-gas

Comments: 4 pages, 3 figures

\\

We describe possible superfluid phases of ultracold dipolar fermions in

optical lattices for two-dimensional systems. Considering the many-body

screening of dipolar interactions at larger filling factors, we show that

several superfluid phases with distinct pairing symmetries naturally emerge in

the singlet channel: local $s$-wave $(sl)$, extended $s$-wave $(se)$, $d$-wave

$(d)$ or time-reversal-symmetry breaking $(sl + se \pm id)$-wave. The

temperature versus filling factor phase diagram indicates that $d$-wave is

favored near half-filling, that $(sl + se)$-wave is favored near zero or full

filling, and that time-reversal-breaking $(sl + se \pm id)$-wave is favored in

between. When a harmonic trap is included a sequence of phases can exist in the

cloud depending on the filling factor at the center of the trap. Most notably

in the region where the $(sl + se \pm id)$-wave superfluid exists, spontaneous

currents are generated, and may be detected using velocity sensitive Bragg

spectroscopy.

\\ ( http://arxiv.org/abs/1006.2072 , 66kb)

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\\

arXiv:1006.2118

Date: Thu, 10 Jun 2010 19:08:38 GMT (115kb)

Title: Hidden Sp(2s+1)- or SO(2s+1)-symmetry and new exactly solvable models in

ultracold atomic systems

Authors: Yuzhu Jiang, Junpeng Cao and Yupeng Wang

Categories: cond-mat.str-el

Comments: 6 pages, 2 figures

\\

The high spin ultracold atom models with a special form of contact

interactions, i.e., the scattering lengthes in the total spin-$2,4 \cdots$

channels are equal but may be different from that in the spin-0 channel, is

studied. It is found that those models have either $Sp(2s+1)$-symmetry for the

fermions or $SO(2s+1)$-symmetry for the bosons in the spin sector. Based on the

symmetry analysis, a new class of exactly solvable models is proposed and

solved via the Bethe ansatz. The ground states for repulsive fermions are also

discussed.

\\ ( http://arxiv.org/abs/1006.2118 , 115kb)

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The replacements:

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\\

arXiv:0809.3532

replaced with revised version Mon, 7 Jun 2010 06:29:38 GMT (218kb)

Title: Spontaneous generation of a half-quantum vortex in spin-orbit coupled

Bose-Einstein condensates

Authors: Congjun Wu and Ian Mondragon-Shem

Categories: cond-mat.supr-con

\\ ( http://arxiv.org/abs/0809.3532 , 218kb)

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\\

arXiv:0912.3667

replaced with revised version Mon, 7 Jun 2010 00:09:42 GMT (33kb)

Title: Comment on "Coherent Ratchets in Driven Bose-Einstein Condensates"

Authors: G. Benenti, G. Casati, S. Denisov, S. Flach, P. Hanggi, B. Li, and D.

Poletti

Categories: cond-mat.quant-gas

Comments: revised version

Journal-ref: Phys. Rev. Lett. 104, 228901 (2010)

DOI: 10.1103/PhysRevLett.104.228901

\\ ( http://arxiv.org/abs/0912.3667 , 33kb)

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\\

arXiv:1002.0453

replaced with revised version Tue, 8 Jun 2010 12:52:33 GMT (1405kb)

Title: A finite element method with mesh adaptivity for computing vortex states

in fast-rotating Bose-Einstein condensates

Authors: Ionut Danaila (LJLL), Frederic Hecht (LJLL)

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

Comments: to appear in J. Computational Physics

\\ ( http://arxiv.org/abs/1002.0453 , 1405kb)

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\\

arXiv:1002.2311

replaced with revised version Fri, 4 Jun 2010 12:44:58 GMT (307kb)

Title: Imaging a single atom in a time-of-flight experiment

Authors: A. Fuhrmanek, A.M. Lance, C. Tuchendler, P. Grangier, Y.R.P. Sortais

and A. Browaeys

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

Comments: 14 pages, 8 figures

Journal-ref: New Journal of Physics 12, 053028 (2010)

\\ ( http://arxiv.org/abs/1002.2311 , 307kb)

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\\

arXiv:1002.3016

replaced with revised version Tue, 8 Jun 2010 13:57:09 GMT (3595kb)

Title: Photoemission spectrum and effect of inhomogeneous pairing fluctuations

in the BCS-BEC crossover regime of an ultracold Fermi gas

Authors: Shunji Tsuchiya, Ryota Watanabe, and Yoji Ohashi

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

Comments: 5 pages, 5 figures, Figures 4 and 5 are updated including

experimental data

\\ ( http://arxiv.org/abs/1002.3016 , 3595kb)

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\\

arXiv:1003.2634

replaced with revised version Thu, 10 Jun 2010 04:27:09 GMT (21kb)

Title: Antiferromagnetic Spinor Condensates are Quantum Rotors

Authors: Ryan Barnett, Jay D. Sau, and S. Das Sarma

Categories: cond-mat.quant-gas

Comments: minor revisions. some typos corrected

\\ ( http://arxiv.org/abs/1003.2634 , 21kb)

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\\

arXiv:1005.3577

replaced with revised version Wed, 9 Jun 2010 02:20:08 GMT (324kb)

Title: Time-of-flight imaging method to observe signatures of

antiferromagnetically ordered states of fermionic atoms in an optical lattice

Authors: Kensuke Inaba and Makoto Yamashita

Categories: cond-mat.quant-gas

Comments: 4 pages, 5 figures

\\ ( http://arxiv.org/abs/1005.3577 , 324kb)

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\\

arXiv:1006.1522 (*cross-listing*)

replaced with revised version Wed, 9 Jun 2010 13:25:49 GMT (0kb,I)

Title: Does Floquet theory always work?

Authors: Kushal Shah and Harishankar Ramachandran

Categories: physics.plasm-ph cond-mat.soft math-ph math.CA math.MP

Comments: This paper has been withdrawn by the authors. This paper is currently

under revision

\\ ( http://arxiv.org/abs/1006.1522 , 0kb)

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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 Sep 01 2010 - 11:01:37 EST

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