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

Date: Tue, 06 Jan 2009 09:40:38 +1000

Date: Tue, 06 Jan 2009 09:40:38 +1000

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

Hi everyone,

I have spend the last month away from home, and despite the best of intentions I

didn't manage to complete any arXiv selection emails. I hope to quickly catch

up in the coming days.

I would like to wish all subscribers a happy new year!

There are 31 new preprints and 4 replacements in this post.

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arXiv:0811.3454

Date: Fri, 21 Nov 2008 02:19:24 GMT (203kb)

Title: LDA+Gutzwiller Method for Correlated Electron Systems: Formalism and Its

Applications

Authors: XiaoYu Deng, Lei Wang, Xi Dai, Zhong Fang

Categories: cond-mat.str-el

Comments: 20 pages, 11 figures

\\

We introduce in detail our newly developed \textit{ab initio}

LDA+Gutzwiller method, in which the Gutzwiller variational approach is

naturally incorporated with the density functional theory (DFT) through the

"Gutzwiller density functional theory (GDFT)" (which is a generalization of

original Kohn-Sham formalism). This method can be used for ground state

determination of electron systems ranging from weakly correlated metal to

strongly correlated insulators with long-range ordering. We will show that its

quality for ground state is as high as that by dynamic mean field theory

(DMFT), and yet it is computationally much cheaper. In additions, the method is

fully variational, the charge-density self-consistency can be naturally

achieved, and the quantities, such as total energy, linear response, can be

accurately obtained similar to LDA-type calculations. Applications on several

typical systems are presented, and the characteristic aspects of this new

method are clarified. The obtained results using LDA+Gutzwiller are in better

agreement with existing experiments, suggesting significant improvements over

LDA or LDA+U.

\\ ( http://arxiv.org/abs/0811.3454 , 203kb)

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arXiv:0811.3578

Date: Fri, 21 Nov 2008 16:45:53 GMT (38kb)

Title: Three-body Recombination of Fermionic Atoms with Large Scattering

Lengths

Authors: Eric Braaten, H.-W. Hammer, Daekyoung Kang, Lucas Platter

Categories: cond-mat.other

Comments: 4 pages, 4 figures

Report-no: HISKP-TH-08/19

\\

The 3-body recombination rate at threshold for fermions with three spin

states and large scattering lengths is calculated in the zero-range

approximation. The only parameters in this limit are the three scattering

lengths and the Efimov parameter, which can be complex valued. Semi-analytic

results are obtained for the cases of negative scattering lengths, two of which

are equal. The general result is applied to the three lowest hyperfine states

of Lithium-6 atoms in regions of the magnetic field in which the three

scattering lengths are all large and negative. Comparisons with recent

experiments provide indications of loss features associated with Efimov trimers

near the 3-atom threshold.

\\ ( http://arxiv.org/abs/0811.3578 , 38kb)

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arXiv:0811.3598

Date: Fri, 21 Nov 2008 18:15:41 GMT (55kb)

Title: Solid 4He and the Supersolid Phase: from Theoretical Speculation to the

Discovery of a New State of Matter? A Review of the Past and Present Status

of Research

Authors: D.E. Galli and L. Reatto

Categories: cond-mat.stat-mech

Comments: Published on J. Phys. Soc. Jpn., Vol.77, No.11, p.111010

\\

The possibility of a supersolid state of matter, i.e., a crystalline solid

exhibiting superfluid properties, first appeared in theoretical studies about

forty years ago. After a long period of little interest due to the lack of

experimental evidence, it has attracted strong experimental and theoretical

attention in the last few years since Kim and Chan (Penn State, USA) reported

evidence for nonclassical rotational inertia effects, a typical signature of

superfluidity, in samples of solid 4He. Since this "first observation", other

experimental groups have observed such effects in the response to the rotation

of samples of crystalline helium, and it has become clear that the response of

the solid is extremely sensitive to growth conditions, annealing processes, and

3He impurities. A peak in the specific heat in the same range of temperatures

has been reported as well as anomalies in the elastic behaviour of solid 4He

with a strong resemblance to the phenomena revealed by torsional oscillator

experiments. Very recently, the observation of unusual mass transport in hcp

solid 4He has also been reported, suggesting superflow. From the theoretical

point of view, powerful simulation methods have been used to study solid 4He,

but the interpretation of the data is still rather difficult; dealing with the

question of supersolidity means that one has to face not only the problem of

the coexistence of quantum coherence phenomena and crystalline order, exploring

the realm of spontaneous symmetry breaking and quantum field theory, but also

the problem of the role of disorder, i.e., how defects, such as vacancies,

impurities, dislocations, and grain boundaries, participate in the phase

transition mechanism.

\\ ( http://arxiv.org/abs/0811.3598 , 55kb)

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arXiv:0811.3623

Date: Fri, 21 Nov 2008 19:56:48 GMT (65kb)

Title: Superfluid-density of the ultra-cold Fermi gas in optical lattices

Authors: T. Paananen

Categories: cond-mat.other

Comments: 20 pages, 7 figures

\\

In this paper we study the superfluid density of the two component Fermi gas

in optical lattices with population imbalance. Three different type of phases,

the BCS-state (Bardeen, Cooper, and Schieffer), the FFLO-state (Fulde, Ferrel,

Larkin, and Ovchinnikov), and Sarma state, are considered. We show that the

FFLO superfluid density differs crucially from the BCS/Sarma superfluid

density. Although there are dynamical instabilities in the FFLO phase, when the

interaction is strong or densities are high, on the weak coupling limit the

FFLO phase is stable.

\\ ( http://arxiv.org/abs/0811.3623 , 65kb)

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arXiv:0811.3509

Date: Fri, 21 Nov 2008 10:48:55 GMT (189kb,D)

Title: Negative specific heat from the partition function of a free damped

particle

Authors: Gert-Ludwig Ingold, Peter H\"anggi, and Peter Talkner

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

Comments: 7 pages, 6 figures, physeauth.cls and elsart.cls v2.18 included

\\

The definition of the specific heat for a damped quantum system is a subtle

issue. A possible approach is based on an effective partition function defined

as the ratio of the partition functions of system plus bath and of the bath

alone. For the free damped particle it has been shown, however, that the

ensuing specific heat may become negative for appropriately chosen

environments. We argue that this quantity should be interpreted as the change

of the specific heat of the heat bath when the system degrees of freedom are

coupled to it. While this difference may become negative, the involved specific

heats themselves are always positive and therefore thermodynamic stability is

always guaranteed. For a damped harmonic oscillator, instead of negative

values, under appropriate conditions one can observe a dip in the difference of

specific heats as a function of temperature. Minimal models containing a single

oscillator heat bath are employed to elucidate the temperature dependence of

the difference of specific heats. Finally, we comment on the consequences for

the interpretation of the density of states based on the effective partition

function.

\\ ( http://arxiv.org/abs/0811.3509 , 189kb)

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arXiv:0811.3684

Date: Sat, 22 Nov 2008 12:16:45 GMT (155kb)

Title: STIRAP transport of Bose-Einstein condensate in triple-well trap

Authors: V.O. Nesterenko, A.N. Novikov, F.F. de Souza Cruz, and E.L. Lapolli

Categories: cond-mat.other

Comments: 9 pages, 6 figures. To be published in Laser Physics (v. 19, n.4,

2009)

\\

The irreversible transport of multi-component Bose-Einstein condensate (BEC)

is investigated within the Stimulated Adiabatic Raman Passage (STIRAP) scheme.

A general formalism for a single BEC in M-well trap is derived and analogy

between multi-photon and tunneling processes is demonstrated. STIRAP transport

of BEC in a cyclic triple-well trap is explored for various values of detuning

and interaction between BEC atoms. It is shown that STIRAP provides a complete

population transfer at zero detuning and interaction and persists at their

modest values. The detuning is found not to be obligatory. The possibility of

non-adiabatic transport with intuitive order of couplings is demonstrated.

Evolution of the condensate phases and generation of dynamical and geometric

phases are inspected. It is shown that STIRAP allows to generate the

unconventional geometrical phase which is now of a keen interest in quantum

computing.

\\ ( http://arxiv.org/abs/0811.3684 , 155kb)

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arXiv:0811.3762

Date: Sun, 23 Nov 2008 17:38:12 GMT (1291kb)

Title: The quantum optical Josephson interferometer

Authors: Dario Gerace, Hakan E. Tureci, A. Imamoglu, Vittorio Giovannetti and

Rosario Fazio

Categories: cond-mat.mes-hall

Comments: 9 pages, 7 figures

\\

The interplay between coherent tunnel coupling and on-site interactions in

dissipation-free bosonic systems has lead to many spectacular observations,

ranging from the demonstration of number-phase uncertainty relation to quantum

phase transitions. To explore the effect of dissipation and coherent drive on

tunnel coupled interacting bosonic systems, we propose a device that is the

quantum optical analog of a Josephson interferometer. It consists of two

coherently driven linear optical cavities connected via a central cavity with a

single-photon nonlinearity. The Josephson-like oscillations in the light

emitted from the central cavity as a function of the phase difference between

two pumping fields can be suppressed by increasing the strength of the

nonlinear coupling. Remarkably, we find that in the limit of ultra-strong

interactions in the center-cavity, the coupled system maps on to an effective

Jaynes-Cummings system with a nonlinearity determined by the tunnel coupling

strength. In the limit of a single nonlinear cavity coupled to two linear

waveguides, the degree of photon antibunching from the nonlinear cavity

provides an excellent measure of the transition to the nonlinear regime where

Josephson oscillations are suppressed.

\\ ( http://arxiv.org/abs/0811.3762 , 1291kb)

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arXiv:0811.3793

Date: Mon, 24 Nov 2008 14:07:24 GMT (413kb)

Title: Finite Temperature Phase Diagram in Rotating Bosonic Optical Lattice

Authors: Beibing Huang, Shaolong Wan

Categories: cond-mat.str-el

Comments: 10 pages, 2 figures

\\

Finite temperature phase boundary between superfluid phase and normal state

is analytically derived by studying the stability of normal state in rotating

bosonic optical lattice. We also prove that the oscillation behavior of

critical hopping matrix directly follows the upper boundary of Hofstadter

butterfly as the function of effective magnetic field.

\\ ( http://arxiv.org/abs/0811.3793 , 413kb)

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arXiv:0811.3795

Date: Mon, 24 Nov 2008 02:52:08 GMT (6kb)

Title: Oscillation of Pauli Paramagnetism in Rotating Two-Component Fermionic

Atom Gases

Authors: Beibing Huang, Shaolong Wan

Categories: cond-mat.str-el cond-mat.stat-mech

Comments: 5 pages,

\\

By rotating two-component fermionic atom gases in uniform magnetic field, a

similar physical situation with de Haas-van Alphen effect is constructed. We

calculate magnetic moment of the system and find that owing to an existence of

effective magnetic field coming from the rotation, the magnetic moment also

shows the oscillatory behavior about magnetic field, but it is completely

different from the famous oscillation of de Haas-van Alphen effect. This

distinction is due to that in the atomic gases the orbital motion of atom only

couples to rotation and does not contribute to magnetic moment in the light of

atomic charge neutrality.

\\ ( http://arxiv.org/abs/0811.3795 , 6kb)

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arXiv:0811.3881

Date: Mon, 24 Nov 2008 14:34:37 GMT (60kb)

Title: Polaron Properties of an Impurity in Bose-Einstein-Condensation

Authors: Beibing Huang, Shaolong Wan

Categories: cond-mat.stat-mech cond-mat.str-el

Comments: 13 pages, 3 figures

\\

In this paper we study an impurity in Bose-Einstein-Condensate system at

$T=0K$ and suppose the contact forms for boson-boson and boson-impurity

interactions. Using Bogoliubov theory and a further approximation corresponding

to only think over the forward scattering of impurity by bosons, we derive a

reduced Hamiltonian whose form is the same as the Fr\"{o}hlich Hamiltonian for

large polaron. By using Lee-Low-Pines (LLP) theory for large polaron, we obtain

the effective mass of impurity, the phonon number carried by impurity and the

energy related to the existence of impurity. In addition, we also discuss the

valid range for forward-scattering approximation.

\\ ( http://arxiv.org/abs/0811.3881 , 60kb)

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arXiv:0811.3909

Date: Mon, 24 Nov 2008 17:37:51 GMT (26kb)

Title: Microwave Photon Detector in Circuit QED

Authors: G. Romero, J. J. Garcia-Ripoll, E. Solano

Categories: cond-mat.mes-hall

\\

Quantum optical photodetection has occupied a central role in understanding

radiation-matter interactions. It has also contributed to the development of

atomic physics and quantum optics, including applications to metrology,

spectroscopy, and quantum information processing. The quantum microwave regime,

originally explored using cavities and atoms, is seeing a novel boost with the

generation of nonclassical propagating fields in circuit quantum

electrodynamics (QED). This promising field, involving potential developments

in quantum information with microwave photons, suffers from the absence of

photodetectors. Here, we design a metamaterial composed of discrete

superconducting elements that implements a high-efficiency microwave photon

detector. Our design consists of a microwave guide coupled to an array of

metastable quantum circuits, whose internal states are irreversibly changed due

to the absorption of photons. This proposal can be widely applied to different

physical systems and can be generalized to implement a microwave photon

counter.

\\ ( http://arxiv.org/abs/0811.3909 , 26kb)

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arXiv:0811.3961

Date: Mon, 24 Nov 2008 20:58:55 GMT (1108kb,D)

Title: A practical scheme for a light-induced gauge field in an atomic Bose gas

Authors: Kenneth J. G\"{u}nter, Marc Cheneau, Tarik Yefsah, Steffen Patrick

Rath, and Jean Dalibard

Categories: cond-mat.str-el cond-mat.mes-hall

Comments: 4 pages, 3 figures

\\

We propose a scheme to generate an Abelian gauge field in an atomic gas using

two crossed laser beams. If the internal atomic state follows adiabatically the

eigenstates of the atom-laser interaction, Berry's phase gives rise to a vector

potential that can nucleate vortices in a Bose gas. The present scheme operates

even for a large detuning with respect to the atomic resonance, making it

applicable to alkali atoms without significant heating due to spontaneous

emission. We test the validity of the adiabatic approximation by integrating

the set of coupled Gross-Pitaevskii equations associated with the various

internal atomic states, and we show that the steady state of the interacting

gas indeed exhibits a vortex lattice, as expected from the adiabatic gauge

field.

\\ ( http://arxiv.org/abs/0811.3961 , 1108kb)

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arXiv:0811.3634

Date: Fri, 21 Nov 2008 21:03:19 GMT (996kb,D)

Title: Accurate Microwave Control and Real-Time Diagnostics of Neutral Atom

Qubits

Authors: W. Rakreungdet (1), J. H. Lee (1), K. F. Lee (2), B. E. Mischuck (3),

Enrique Montano (1) and P. S. Jessen (1) ((1) College of Optical Sciences,

University of Arizona, (2) Department of Physics, Michigan Technological

University, (3) Department of Physics and Astronomy, University of New

Mexico)

Categories: quant-ph

Comments: 9 pages, 7 figures

\\

We demonstrate accurate single-qubit control in an ensemble of atomic qubits

trapped in an optical lattice. The qubits are driven with microwave radiation,

and their dynamics tracked by optical probe polarimetry. Real-time diagnostics

is crucial to minimize systematic errors and optimize the performance of

single-qubit gates, leading to fidelities of 0.99 for single-qubit pi

rotations. We show that increased robustness to large, deliberately introduced

errors can be achieved through the use of composite rotations. However, during

normal operation the combination of very small intrinsic errors and additional

decoherence during the longer pulse sequences precludes any significant

performance gain in our current experiment.

\\ ( http://arxiv.org/abs/0811.3634 , 996kb)

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arXiv:0811.3853

Date: Mon, 24 Nov 2008 12:17:11 GMT (33kb)

Title: Many-body theory for systems with particle conversion: Extending the

multiconfigurational time-dependent Hartree method

Authors: Ofir E. Alon, Alexej I. Streltsov, and Lorenz S. Cederbaum

Categories: quant-ph

Comments: 46 pages

\\

We derive a multiconfigurational time-dependent Hartree theory for systems

with particle conversion. In such systems particles of one kind can convert to

another kind and the total number of particles varies in time. The theory thus

extends the scope of the available and successful multiconfigurational

time-dependent Hartree methods -- which were solely formulated for and applied

to systems with a fixed number of particles -- to new physical systems and

problems. As a guiding example we treat explicitly a system where bosonic atoms

can combine to form bosonic molecules and vise versa. In the theory for

particle conversion, the time-dependent many-particle wavefunction is written

as a sum of configurations made of a different number of particles, and

assembled from sets of atomic and molecular orbitals. Both the expansion

coefficients and the orbitals forming the configurations are time-dependent

quantities that are fully determined according to the Dirac-Frenkel

time-dependent variational principle. Particular attention is paid to the

reduced density matrices of the many-particle wavefunction that appear in the

theory and enter the equations of motion. There are two kinds of reduced

density matrices: particle-conserving reduced density matrices which directly

only couple configurations with the same number of atoms and molecules, and

particle non-conserving reduced density matrices which couple configurations

with a different number of atoms and molecules. Closed-form and compact

equations of motion are derived for contact as well as general two-body

interactions, and their properties are analyzed and discussed.

\\ ( http://arxiv.org/abs/0811.3853 , 33kb)

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arXiv:0811.3780

Date: Sun, 23 Nov 2008 22:42:53 GMT (370kb)

Title: Lattice Interferometer for Ultra-Cold Atoms

Authors: Mikkel F. Andersen, Tycho Sleator

Categories: physics.atom-ph

\\

We demonstrate an atomic interferometer based on ultra-cold atoms released

from an optical lattice. This technique yields a large improvement in signal to

noise over a related interferometer previously demonstrated. The interferometer

involves diffraction of the atoms using a pulsed optical lattice. For short

pulses a simple analytical theory predicts the expected signal. We investigate

the interferometer for both short pulses and longer pulses where the analytical

theory break down. Longer pulses can improve the precision and signal size. For

specific pulse lengths we observe a coherent signal at times that differs

greatly from what is expected from the short pulse model. The interferometric

signal also reveals information about the dynamics of the atoms in the lattice.

We investigate the application of the interferometer for a measurement of

$h/m_A$ that together with other well known constants constitutes a measurement

of the fine structure constant.

\\ ( http://arxiv.org/abs/0811.3780 , 370kb)

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arXiv:0811.4034

Date: Tue, 25 Nov 2008 08:53:21 GMT (428kb)

Title: Analysis and calibration of absorptive images of Bose-Einstein

condensate at non-zero temperatures

Authors: J. Szczepkowski, R. Gartman, M. Witkowski, L. Tracewski, M. Zawada, W.

Gawlik

Categories: cond-mat.other

Comments: 17 pages, 8 figures

\\

We describe the method allowing quantitative interpretation of absorptive

images of mixtures of BEC and thermal atoms which reduces possible systematic

errors associated with evaluation of the contribution of each fraction. By

using known temperature dependence of the BEC fraction, the analysis allows

precise calibration of the fitting results. The developed method is verified in

two different measurements and compares well with theoretical calculations and

with measurements performed by another group.

\\ ( http://arxiv.org/abs/0811.4034 , 428kb)

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arXiv:0811.4147

Date: Tue, 25 Nov 2008 18:10:13 GMT (207kb)

Title: Coupling internal atomic states in a two-component Bose-Einstein

condensate via an optical lattice: Extended Mott-superfluid transitions

Authors: Jonas Larson and Jani-Petri Martikainen

Categories: cond-mat.other

Comments: 9 pages, 7 figures

\\

An ultracold gas of coupled two-component atoms in an optical lattice is

studied. A systematic derivation of a Bose-Hubbard model is presented, and we

explicitly demonstrate that the hopping coefficient amongst neighboring sites

may be tuned between positive and negative values. This originates from the

interplay between atomic kinetic, atomic internal and atom-atom interaction

energies. As a consequence, the superfluid phase is divided into ferromagnetic

and antiferromagnetic like states. Furthermore, also the Mott phase is

separated into two distinguishable states. By means of the strong coupling

expansion, we find the full phase diagram of the four different phases.

\\ ( http://arxiv.org/abs/0811.4147 , 207kb)

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arXiv:0811.3967

Date: Mon, 24 Nov 2008 21:01:32 GMT (1143kb,D)

Title: Dynamical Coupling between a Bose-Einstein Condensate and a Cavity

Optical Lattice

Authors: Stephan Ritter, Ferdinand Brennecke, Christine Guerlin, Kristian

Baumann, Tobias Donner, Tilman Esslinger

Categories: quant-ph

Comments: 5 pages, 4 figures

\\

A Bose-Einstein condensate is dispersively coupled to a single mode of an

ultra-high finesse optical cavity. The system is governed by strong

interactions between the atomic motion and the light field even at the level of

single quanta. While coherently pumping the cavity mode the condensate is

subject to the cavity optical lattice potential whose depth depends nonlinearly

on the atomic density distribution. We observe bistability already below the

single photon level and strong back-action dynamics which tunes the system

periodically out of resonance.

\\ ( http://arxiv.org/abs/0811.3967 , 1143kb)

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arXiv:0811.3971

Date: Mon, 24 Nov 2008 21:06:30 GMT (122kb)

Title: Prospects for application of ultracold Sr$_2$ molecules in precision

measurements

Authors: S. Kotochigova, T. Zelevinsky, and Jun Ye

Categories: quant-ph

Comments: 8 pages, 10 figures

\\

Precision measurements with ultracold molecules require development of robust

and sensitive techniques to produce and interrogate the molecules. With this

goal, we theoretically analyze factors that affect frequency measurements

between rovibrational levels of the Sr$_2$ molecule in the electronic ground

state. This measurement can be used to constrain the possible time variation of

the proton-electron mass ratio. Sr$_2$ is expected to be a strong candidate for

achieving high precision due to the spinless nature and ease of cooling and

perturbation-free trapping of Sr \cite{Zelevinsky2008}. The analysis includes

calculations of two-photon transition dipole moments between deeply and weakly

bound vibrational levels, lifetimes of intermediate excited states, and Stark

shifts of the vibrational levels by the optical lattice field, including

possibilities of Stark-cancellation trapping.

\\ ( http://arxiv.org/abs/0811.3971 , 122kb)

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arXiv:0811.3993

Date: Mon, 24 Nov 2008 23:19:11 GMT (30kb)

Title: Bloch-Zener oscillations of atoms inside an optical cavity

Authors: B. Prasanna Venkatesh, M. Trupke, E.A. Hinds, D.H.J. O'Dell

Categories: quant-ph

Comments: 4 pages, 2 figures

\\

Cold atoms in an optical lattice execute Bloch-Zener oscillations when they

are accelerated. We investigate the corresponding behavior of the atoms and the

light when the optical lattice is provided by the intra-cavity field of a

driven Fabry-Perot resonator. When the atoms oscillate inside the resonator, we

find that their back-action modulates the phase and intensity of the light

transmitted through the cavity. We solve the coupled atom-light equations

self-consistently and show that, remarkably, the Bloch period is unaffected by

this back-action. The transmitted light provides a way to observe the atomic

oscillation continuously, allowing very high precision measurements to be

derived from a single cloud of atoms.

\\ ( http://arxiv.org/abs/0811.3993 , 30kb)

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arXiv:0811.3992

Date: Mon, 24 Nov 2008 23:07:23 GMT (1190kb)

Title: Variation of the Fine-Structure Constant and Laser Cooling of Atomic

Dysprosium

Authors: N. A. Leefer, A. Cing\"oz, D. Budker, S. J. Ferrell, V. V. Yashchuk,

A. Lapierre, A.-T Nguyen, S. K. Lamoreaux, J. R. Torgerson

Categories: physics.atom-ph

Comments: 10 pages, 6 figures

\\

Radio-frequency electric-dipole transitions between nearly degenerate,

opposite parity levels of atomic dysprosium (Dy) were monitored over an

eight-month period to search for a variation in the fine-structure constant,

$\alpha$. The data provide a rate of fractional temporal variation of $\alpha$

of $(-2.7\pm2.6)\times 10^{-15}$ yr$^{-1}$ or a value of $(-8.7 \pm 6.6) \times

10^{-6}$ for $k_\alpha$, the variation coefficient for $\alpha$ in a changing

gravitational potential. All results indicate the absence of significant

variation at the present level of sensitivity. We also present initial results

on laser cooling of an atomic beam of dysprosium.

\\ ( http://arxiv.org/abs/0811.3992 , 1190kb)

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arXiv:0811.4010

Date: Tue, 25 Nov 2008 03:37:56 GMT (258kb)

Title: Lifetime measurements of the 5d states of rubidium

Authors: D. Sheng and A. Perez Galvan and L. A. Orozco

Categories: physics.atom-ph

Comments: 9 pages, 6 figures

\\

We present lifetime measurements of the $5D_{3/2}$ and $5D_{5/2}$ states of

rubidium using the time correlated single photon counting method. We perform

the experiment in a magneto-optical trap of $^{87}$Rb atoms using a two-step

excitation with the trap laser at 780 nm as the first step. We record the 761.9

nm fluorescence from the decay of the $5D_{3/2}$ state to the $5P_{1/2}$ state,

and measure the lifetime of the $5D_{3/2}$ state $\tau=246.3(1.6)$ ns. We

record the 420.2 nm fluorescence from the cascade decay of the $5D_{5/2}$ state

to the $5S_{1/2}$ state through the $6P_{3/2}$ state, and extract the lifetime

of the $5D_{5/2}$ state ${\tau}=238.5(2.3)$ ns.

\\ ( http://arxiv.org/abs/0811.4010 , 258kb)

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arXiv:0811.4086

Date: Tue, 25 Nov 2008 14:19:25 GMT (320kb,D)

Title: A possible Efimov trimer state in 3-component lithium 6

Authors: Pascal Naidon and Masahito Ueda

Categories: physics.atom-ph

Comments: 4 pages, 2 figures

\\

We consider the Efimov trimer theory as a possible framework to explain

recently observed losses by inelastic three-body collisions in a

three-hyperfine-component ultracold mixture of lithium 6. Within this

framework, these losses would arise chiefly from the existence of an Efimov

trimer bound state below the continuum of free triplets of atoms, and the loss

maxima (at certain values of an applied magnetic field) would correspond to

zero-energy resonances where the trimer dissociates into three free atoms. Our

results show that such a trimer state is indeed possible given the two-body

scattering lengths in the three-component lithium mixture, and gives rise to

two zero-energy resonances. The locations of these resonances appear to be

consistent with observed losses.

\\ ( http://arxiv.org/abs/0811.4086 , 320kb)

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arXiv:0811.4123

Date: Tue, 25 Nov 2008 16:39:50 GMT (898kb,D)

Title: Nonadiabatic transitions in electrostatically trapped ammonia molecules

Authors: Moritz Kirste, Boris Saratakov, Melanie Schnell, Gerard Meijer

Categories: physics.atom-ph physics.chem-ph

\\

Nonadiabatic transitions are known to be major loss channels for atoms in

magnetic traps, but have thus far not been experimentally reported upon for

trapped molecules. We have observed and quantified losses due to nonadiabatic

transitions for three isotopologues of ammonia in electrostatic traps, by

comparing the trapping times in traps with a zero and a non-zero electric field

at the center. Nonadiabatic transitions are seen to dominate the overall loss

rate even for samples at relatively high temperatures of 10-50 mK.

\\ ( http://arxiv.org/abs/0811.4123 , 898kb)

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arXiv:0811.4284

Date: Wed, 26 Nov 2008 12:31:07 GMT (111kb,D)

Title: Scattering Resonances in a Degenerate Fermi Gas

Authors: K. J. Challis, N. Nygaard, K. M{\o}lmer

Categories: cond-mat.other

Comments: 8 pages, 5 figures

\\

We consider elastic single-particle scattering from a one-dimensional

two-component trapped superfluid Fermi gas when the incoming projectile

particle is identical to one of the confined species. Our theoretical treatment

is based on the Hartree-Fock ground state of the trapped gas and a

configuration-interaction description of the excitations. We determine the

scattering phase shifts for the system and predict Fano-type scattering

resonances that are a direct consequence of inter-atomic pairing. We describe

the main characteristics of the scattering resonances and make a comparison

with the results of BCS mean-field theory.

\\ ( http://arxiv.org/abs/0811.4284 , 111kb)

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arXiv:0811.4333

Date: Wed, 26 Nov 2008 15:01:59 GMT (15kb)

Title: Coherence properties of the microcavity polariton condensate

Authors: D. M. Whittaker and P. R. Eastham

Categories: cond-mat.str-el cond-mat.mes-hall

Comments: 5 pages, 1 figure

\\

A theoretical model is presented which explains the dominant decoherence

process in a microcavity polariton condensate. The mechanism which is invoked

is the effect of self-phase modulation, whereby interactions transform

polariton number fluctuations into random energy variations. The model shows

that the phase coherence decay, g1(t), has a Kubo form, which can be Gaussian

or exponential, depending on whether the number fluctuations are slow or fast.

This fluctuation rate also determines the decay time of the intensity

correlation function, g2(t), so it can be directly determined experimentally.

The model explains recent experimental measurements of a relatively fast

Gaussian decay for g1(t), but also predicts a regime, further above threshold,

where the decay is much slower.

\\ ( http://arxiv.org/abs/0811.4333 , 15kb)

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arXiv:0811.4185

Date: Tue, 25 Nov 2008 23:42:05 GMT (562kb)

Title: Investigation of dephasing rates in an interacting Rydberg gas

Authors: U. Raitzsch, R. Heidemann, H. Weimer, V. Bendkowsky, B. Butscher, P.

Kollmann, R. L\"ow, H. P. B\"uchler, T. Pfau

Categories: quant-ph

Comments: 13 pages, 5 figures

\\

We experimentally and theoretically investigate the dephasing rates of the

coherent evolution of a resonantly driven pseudo spin emersed in a reservoir of

pseudo spins. The pseudo spin is realized by optically exciting 87 Rb atoms to

a Rydberg state. Hence, the upper spin states are coupled via the strong van

der Waals interaction. Two different experimental techniques to measure the

dephasing rates are shown: the 'rotary echo' technique known from nuclear

magnetic resonance physics and electromagnetically induced transparency. The

experiments are performed in a dense frozen Rydberg gas, either confined in a

magnetic trap or in an optical dipole trap. Additionally, a numerical

simulation is used to analyse the dephasing in the rotary echo experiments.

\\ ( http://arxiv.org/abs/0811.4185 , 562kb)

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arXiv:0811.4307

Date: Wed, 26 Nov 2008 13:38:21 GMT (17kb)

Title: Nonequilibrium thermal Casimir-Polder forces

Authors: Stefan Yoshi Buhmann and Stefan Scheel

Categories: quant-ph

Comments: 5 pages

\\

We study the nonequilibrium Casimir-Polder force on an atom prepared in an

incoherent superposition of internal energy-eigenstates, which is placed in a

magnetoelectric environment of nonuniform temperature. After solving the

coupled atom--field dynamics within the framework of macroscopic quantum

electrodynamics, we derive a general expression for the thermal Casimir-Polder

force.

\\ ( http://arxiv.org/abs/0811.4307 , 17kb)

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arXiv:0811.4337

Date: Wed, 26 Nov 2008 15:12:57 GMT (462kb)

Title: Nonlinear dynamics of a cigar-shaped Bose-Einstein condensate coupled

with a single cavity mode

Authors: J. M. Zhang, F. C. Cui, D. L. Zhou, and W. M. Liu

Categories: quant-ph

Comments: 8 pages, 5 figures

\\

We investigate the nonlinear dynamics of a combined system which is composed

of a cigar-shaped Bose-Einstein condensate and an optical cavity. The two sides

couple dispersively. This system is characterized by its nonlinearity: after

integrating out the freedom of the cavity mode, the potential felt by the

condensate depends on the condensate itself. We develop a discrete-mode

approximation for the condensate. Based on this approximation, we map out the

steady configurations of the system. It is found that due to the nonlinearity

of the system, the nonlinear levels of the system can fold up in some parameter

regimes. That will lead to the breakdown of adiabaticity. Analysis of the

dynamical stability of the steady states indicates that the same level

structure also results in optical bistability.

\\ ( http://arxiv.org/abs/0811.4337 , 462kb)

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arXiv:0811.4282

Date: Wed, 26 Nov 2008 12:04:56 GMT (192kb)

Title: A Feshbach resonance in d-wave collisions

Authors: Q. Beaufils, A. Crubellier, T. Zanon, B. Laburthe-Tolra, E. Marechal,

L. Vernac, and O. Gorceix

Categories: physics.atom-ph

Comments: 8 pages, 5 figures

\\

We analyse a narrow Feshbach resonance with ultra-cold chromium atoms

colliding in d-wave. The resonance is made possible by dipole-dipole

interactions, which couple an incoming $l=2$ collision channel with a bound

molecular state with $l=0$. We find that three-body losses associated to this

resonance increase with temperature, and that the loss feature width as a

function of magnetic field also increases linearly with temperature. The

analysis of our experimental data shows that the Feshbach coupling is small

compared both to the temperature and to the density limited lifetime of the

resonant bound molecular state. One consequence is that the three body losse

rate is proportionnal to the square of the number of atoms, and that we can

directly relate the amplitude of the losses to the Feshbach coupling parameter.

We compare our measurement to a calculation of the coupling between the

collisionnal channel and the molecular bound state by dipole-dipole

interactions, and find a good agreement, with no adjustable parameter. An

analysis of the loss lineshape is also performed, which enables to precisely

measure the position of the resonance.

\\ ( http://arxiv.org/abs/0811.4282 , 192kb)

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arXiv:0705.1845 (*cross-listing*)

Date: Sun, 13 May 2007 18:33:50 GMT (883kb)

Title: Introduction to protein folding for physicists

Authors: Pablo Echenique

Categories: physics.bio-ph cond-mat.soft physics.chem-ph q-bio.BM

Comments: 53 pages, 18 figures, the figures are at a low resolution due to

arXiv restrictions, for high-res figures, go to http://www.pabloechenique.com

Journal-ref: Contemporary Physics 48 (2007) 81-108

DOI: 10.1080/00107510701520843

\\

The prediction of the three-dimensional native structure of proteins from the

knowledge of their amino acid sequence, known as the protein folding problem,

is one of the most important yet unsolved issues of modern science. Since the

conformational behaviour of flexible molecules is nothing more than a complex

physical problem, increasingly more physicists are moving into the study of

protein systems, bringing with them powerful mathematical and computational

tools, as well as the sharp intuition and deep images inherent to the physics

discipline. This work attempts to facilitate the first steps of such a

transition. In order to achieve this goal, we provide an exhaustive account of

the reasons underlying the protein folding problem enormous relevance and

summarize the present-day status of the methods aimed to solving it. We also

provide an introduction to the particular structure of these biological

heteropolymers, and we physically define the problem stating the assumptions

behind this (commonly implicit) definition. Finally, we review the 'special

flavor' of statistical mechanics that is typically used to study the

astronomically large phase spaces of macromolecules. Throughout the whole work,

much material that is found scattered in the literature has been put together

here to improve comprehension and to serve as a handy reference.

\\ ( http://arxiv.org/abs/0705.1845 , 883kb)

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The replacements:

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arXiv:0808.0409

replaced with revised version Fri, 21 Nov 2008 18:02:43 GMT (21kb)

Title: DC Josephson Effect with Fermi gases in the Bose-Einstein regime

Authors: F. Ancilotto, L. Salasnich, and F. Toigo

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

Comments: 9 pages, 6 figures. In the new version added one figure and some

paragraphs

\\ ( http://arxiv.org/abs/0808.0409 , 21kb)

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arXiv:0810.4455

replaced with revised version Tue, 25 Nov 2008 16:15:11 GMT (249kb)

Title: Collisional decoherence in trapped atom interferometers that use

non-degenerate sources

Authors: James A. Stickney, Matthew B. Squires, James Scoville, Paul Baker, and

Steven Miller

Categories: physics.atom-ph

Comments: (23 pages, 5 figures)

\\ ( http://arxiv.org/abs/0810.4455 , 249kb)

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arXiv:0707.1302

replaced with revised version Tue, 25 Nov 2008 21:55:28 GMT (363kb)

Title: Superfluidity of fermions with repulsive on-site interaction in an

anisotropic optical lattice near a Feshbach resonance

Authors: B. Wang and L.-M. Duan

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

Comments: updated with published version;

Journal-ref: New Journal of Physics 10, 073007 (2008)

\\ ( http://arxiv.org/abs/0707.1302 , 363kb)

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arXiv:0810.2239

replaced with revised version Wed, 26 Nov 2008 16:12:48 GMT (108kb)

Title: Single-photon cooling to the limit of trap dynamics: Maxwell's Demon

near maximum efficiency

Authors: S. Travis Bannerman, Gabriel N. Price, Kirsten Viering, and Mark G.

Raizen

Categories: physics.atom-ph

\\ ( http://arxiv.org/abs/0810.2239 , 108kb)

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Till next time,

Matt.

-- ========================================================================= Dr M. J. Davis, Senior Lecturer in Physics School of Physical Sciences, email: mdavis_at_physics.uq.edu.au University of Queensland, ph : +61 7 334 69824 Brisbane, QLD 4072, fax : +61 7 336 51242 Australia. http://www.physics.uq.edu.au/people/mdavis/ ========================================================================= Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland =========================================================================Received on Tue Jan 06 2009 - 10:40:06 EST

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