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

Date: Fri, 6 Jul 2007 13:21:54 +1000 (EST)

Date: Fri, 6 Jul 2007 13:21:54 +1000 (EST)

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

This week (or rather, that week a couple of weeks ago) has 28 new preprints and

13 replacements:

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arXiv:0706.2259

Date: Fri, 15 Jun 2007 10:06:52 GMT (114kb)

Title: Non-equilibrium coherence dynamics in one-dimensional Bose gases

Authors: S. Hofferberth, I. Lesanovsky, B. Fischer, T. Schumm, J. Schmiedmayer

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

\\

We study universal properties of non-equilibrium dynamics and coherence decay

in one-dimensional quantum systems. By dynamic splitting of a single 1d quasi

Bose-Einstein condensate we create two identical copies in a phase coherent

state. If the two systems are completely isolated, we observe a sub-exponential

coherence decay towards thermal equilibrium as predicted from the Luttinger

liquid model. For tunnel coupled systems we observe decay to a finite

coherence, the matter wave equivalent to phase locking of two individual

lasers.

\\ ( http://arxiv.org/abs/0706.2259 , 114kb)

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arXiv:0706.2290

Date: Fri, 15 Jun 2007 13:15:12 GMT (293kb)

Title: Study of the Born-Oppenheimer Approximation for Mass-Scaling of Cold

Collision Properties

Authors: Stephan Falke, Eberhard Tiemann, Christian Lisdat

Categories: cond-mat.other

Comments: 8 pages, 6 figures

\\

Asymptotic levels of the A $^1\Sigma_u^+$ state of the two isotopomers

$^{39}{\rm K}_2$ and $^{39}{\rm K}^{41}{\rm K}$ up to the dissociation limit

are investigated with a Doppler-free high resolution laser-spectroscopic

experiment in a molecular beam. The observed level structure can be reproduced

correctly only if a mass dependent correction term is introduced for the

interaction potential. The applied relative correction in the depth of the

potential is $10^{-6}$, which is in the order of magnitude expected for

corrections of the Born-Oppenheimer approximation. A similar change in ground

state potentials might lead to significant changes of mass-scaled properties

describing cold collisions like the s-wave scattering length.

\\ ( http://arxiv.org/abs/0706.2290 , 293kb)

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arXiv:0706.2251

Date: Fri, 15 Jun 2007 09:28:56 GMT (40kb)

Title: A polaritonic two-component Bose-Hubbard model

Authors: Michael J. Hartmann, Fernando G.S.L. Brandao and Martin B. Plenio

Categories: quant-ph

Comments: 5 pages, 7 figures

\\

We show that polaritons in an array of interacting micro-cavities with strong

atom-photon coupling can form a two-component Bose-Hubbard model. Both

polariton species are thereby protected against spontaneous emission as their

atomic part is stored in two ground states of the atoms. The parameters of the

effective model can be tuned via the driving strength of external lasers. We

also describe a method to measure the number statistics in one cavity for each

polariton species independently.

\\ ( http://arxiv.org/abs/0706.2251 , 40kb)

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arXiv:0706.2327

Date: Fri, 15 Jun 2007 16:10:34 GMT (143kb)

Title: A Robust Atom-Photon Entanglement Source for Quantum Repeaters

Authors: Shuai Chen, Yu-Ao Chen, Bo Zhao, Zhen-Sheng Yuan, Joerg Schmiedmayer,

and Jian-Wei Pan

Categories: quant-ph

Comments: 4 pages, 4 figures

\\

We demonstrate a novel way to efficiently and very robust create an

entanglement between an atomic and a photonic qubit. A single laser beam is

used to excite one atomic ensemble and two different spatial modes of scattered

Raman fields are collected to generate the atom-photon entanglement. With the

help of build-in quantum memory, the entanglement still exists after 20.5

$\mu$s storage time which is further proved by the violation of CHSH type

Bell's inequality. Our entanglement procedure is the building block for a novel

robust quantum repeater architecture [Zhao et al, Phys. Rev. Lett. 98, 240502

(2007)]. Our approach can be easily extended to generate high dimensional

atom-photon entanglements.

\\ ( http://arxiv.org/abs/0706.2327 , 143kb)

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arXiv:0706.2335

Date: Fri, 15 Jun 2007 17:09:36 GMT (563kb)

Title: Lateral Effects in Fermion Antibunching

Authors: K. Yuasa, P. Facchi, H. Nakazato, I. Ohba, S. Pascazio, S. Tasaki

Categories: quant-ph

Comments: 21 pages, 4 figures

\\

Lateral effects are analyzed in the antibunching of a beam of free

non-interacting fermions. The emission of particles from a source is

dynamically described in a 3D full quantum field-theoretical framework. The

size of the source and the detectors, as well as the temperature of the source

are taken into account and the behavior of the visibility is scrutinized as a

function of these parameters.

\\ ( http://arxiv.org/abs/0706.2335 , 563kb)

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arXiv:0705.1092 (*cross-listing*)

Date: Tue, 8 May 2007 13:35:01 GMT (621kb)

Title: The Unruh effect and entanglement generation for accelerated atoms near

a reflecting boundary

Authors: Jialin Zhang, Hongwei Yu

Categories: gr-qc quant-ph

Comments: 18 pages, 6 figures

Journal-ref: Phys. Rev. D75 (2007)104014

DOI: 10.1103/PhysRevD.75.104014

\\

We study, in the framework of open systems, the entanglement generation of

two independent uniformly accelerated atoms in interaction with the vacuum

fluctuations of massless scalar fields subjected to a reflecting plane

boundary. We demonstrate that, with the presence of the boundary, the

accelerated atoms exhibit distinct features from static ones in a thermal bath

at the corresponding Unruh temperature in terms of the entanglement creation at

the neighborhood of the initial time. In this sense, accelerated atoms in

vacuum do not necessarily have to behave as if they were static in a thermal

bath at the Unruh temperature.

\\ ( http://arxiv.org/abs/0705.1092 , 621kb)

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arXiv:0706.2277

Date: Fri, 15 Jun 2007 12:13:21 GMT (61kb)

Title: Narrow bandwidth interference filter-stabilized diode laser systems for

the manipulation of neutral atoms

Authors: M. Gilowski, Ch. Schubert, M. Zaiser, W. Herr, T. W\"ubbena, T.

Wendrich, T. M\"uller, E.M. Rasel, and W. Ertmer (Institut f\"ur

Quantenoptik, Leibniz Universit\"at Hannover)

Categories: physics.atom-ph physics.optics

Comments: 9 pages, 3 figures, 1 table

\\

We present and investigate different external cavity diode laser (ECDL)

configurations for the manipulation of neutrals atoms, wavelength-stabilized by

a narrow-band high transmission interference filter. A novel diode laser,

providing high output power of more than 1 W, with a linewidth of less than 200

kHz, based on a self-seeded tapered amplifier chip has been developed.

Additionally, we compare the optical and spectral properties of two laser

systems based on common laser diodes, differing in their coating, as well as

one, based on a distributed-feedback (DFB) diode. The linear cavity setup in

all these systems combines a robust and compact design with a high wavelength

tunability and an improved stability of the optical feedback compared to diode

laser setups using diffraction gratings for wavelength discrimination.

\\ ( http://arxiv.org/abs/0706.2277 , 61kb)

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arXiv:0706.2289

Date: Fri, 15 Jun 2007 13:13:21 GMT (164kb)

Title: Laser cooling of unbound atoms in nondissipative optical lattices

Authors: N.A.Matveeva, A.V.Taichenachev, A.M.Tumaikin, V.I.Yudin

Categories: physics.optics

Comments: 18 pages, 7 figures

\\

The semiclassical theory of laser cooling is applied for the analysis of

cooling of unbound atoms with the values of the ground and exited state angular

moments 1/2 in a one-dimensional nondissipative optical lattice. We show that

in the low-saturation limit with respect to the pumping field a qualitative

interpretation of the cooling mechanisms can be made by the consideration of

effective two-level system of the ground-state sublevels. It is clarified that

in the limit of weak Raman transitions the cooling mechanism is similar to the

Doppler mechanism, which is known in the theory of two-level atom. In the limit

of strong Raman transitions the cooling mechanism is similar to the known

Sisyphus mechanism. In the slow atom approximation the analytical expressions

for the coefficients of friction, spontaneous and induced diffusion are given,

and the kinetic temperature is estimated.

\\ ( http://arxiv.org/abs/0706.2289 , 164kb)

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arXiv:0706.2419

Date: Sat, 16 Jun 2007 14:48:35 GMT (69kb)

Title: Bose-Einstein condensation in semiconductors: the key role of dark

excitons

Authors: Monique Combescot, Odile Betbeder-Matibet and Roland Combescot

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

Comments: 4 pages, 3 figures

\\

The non elementary-boson nature of excitons controls Bose-Einstein

condensation in semiconductors. Composite excitons interact predominantly

through Pauli exclusion; this produces dramatic couplings between bright and

dark states. In microcavities, where bright excitons and photons form

polaritons, they force the condensate to be linearly polarized--as observed. In

bulk, they also force linear polarization, but of dark states, due to interband

Coulomb scatterings. To evidence this dark condensate, we thus need indirect

processes, like the shift it induces on the (bright) exciton line.

\\ ( http://arxiv.org/abs/0706.2419 , 69kb)

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arXiv:0706.2450

Date: Sat, 16 Jun 2007 23:00:34 GMT (200kb)

Title: Quantum Control of the Hyperfine Spin of a Cs Atom Ensemble

Authors: Souma Chaudhury, Seth Merkel, Tobias Herr, Andrew Silberfarb, Ivan H.

Deutsch, Poul S. Jessen

Categories: quant-ph

Comments: 4 pages, 4 figures (color)

\\

We demonstrate quantum control of a large spin-angular momentum associated

with the F=3 hyperfine ground state of 133Cs. A combination of time dependent

magnetic fields and a static tensor light shift is used to implement

near-optimal controls and map a fiducial state to a broad range of target

states, with yields in the range 0.8-0.9. Squeezed states are produced also by

an adiabatic scheme that is more robust against errors. Universal control

facilitates the encoding and manipulation of qubits and qudits in atomic ground

states, and may lead to improvement of some precision measurements.

\\ ( http://arxiv.org/abs/0706.2450 , 200kb)

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arXiv:0706.2639

Date: Mon, 18 Jun 2007 18:16:33 GMT (934kb)

Title: Apparatus for excitation and detection of Rydberg atoms in quantum gases

Authors: Robert Loew, Ulrich Raitzsch, Rolf Heidemann, Vera Bendkowsky, Bjoern

Butscher, Axel Grabowski, and Tilman Pfau

Categories: quant-ph

Comments: 10 pages, 9 figures

\\

We present and characterize a versatile experimental setup which allows for

excitation and detection of Rydberg atoms in quantum gases. The novel concept

of the setup features two charged particle detectors and eight electrical field

plates inside the vacuum chamber, which allows the detection and manipulation

of Rydberg atoms. The setup presented here is applicable to all atomic species

used in the field of quantum gases. We describe and characterize the production

of Bose-Einstein condensates, the excitation scheme into Rydberg states, the

detection of Rydberg states by field ionization followed by ion detection and

the various electric field configurations provided by the eight field plates.

\\ ( http://arxiv.org/abs/0706.2639 , 934kb)

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arXiv:0706.2657

Date: Mon, 18 Jun 2007 20:13:06 GMT (59kb)

Title: Self-consistent slave rotor mean field theory for strongly correlated

systems

Authors: Erhai Zhao, Arun Paramekanti (University of Toronto)

Categories: cond-mat.str-el cond-mat.supr-con

Comments: 15 pages, 9 eps figs

\\

Building on work by Florens and Georges, we formulate and study a

self-consistent slave rotor mean field theory for strongly correlated systems.

This approach views the electron, in the strong correlation regime, as a

composite of a neutral spinon and a charged rotor field. We solve the coupled

spinon-rotor model self-consistently using a cluster mean field theory for the

rotors and various ansatzes for the spinon ground state. We illustrate this

approach with a number of examples relevant to ongoing experiments in strongly

correlated electronic systems such as: (i) the phase diagram of the isotropic

triangular lattice organic Mott insulators, (ii) quasiparticle excitations and

tunneling asymmetry in the weakly doped cuprate superconductors, and (iii) the

cyclotron mass of carriers in spin-density wave and U(1) staggered flux (or

d-density wave) normal states of the underdoped cuprates. We compare the

estimated cyclotron mass with results from recent quantum oscillation

experiments in the magnetic field induced normal state of the underdoped

cuprates which appear to find hole pockets. We also comment on the relation of

this normal state to Fermi arcs seen in photoemission experiments. This slave

rotor mean field theory can be generalized to study inhomogeneous states and

strongly interacting models relevant to ultracold atoms in optical lattices.

\\ ( http://arxiv.org/abs/0706.2657 , 59kb)

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arXiv:0706.2703

Date: Tue, 19 Jun 2007 02:50:23 GMT (651kb)

Title: Exact Solitonic Solutions of the Gross-Pitaevskii Equation with a Linear

Potential

Authors: U. Al Khawaja

Categories: cond-mat.other

\\

We derive classes of exact solitonic solutions of the time-dependent

Gross-Pitaevskii equation with repulsive and attractive interatomic

interactions. The solutions correspond to a string of bright solitons with

phase difference between adjacent solitons equal to $\pi$. While the relative

phase, width, and distance between adjacent solitons turn out to be a constant

of the motion, the center of mass of the string moves with a constant

acceleration arising from the inhomogeneity of the background.

\\ ( http://arxiv.org/abs/0706.2703 , 651kb)

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arXiv:0706.2705

Date: Tue, 19 Jun 2007 03:08:32 GMT (774kb)

Title: Exact Solitonic Solutions of the One-Dimensional Gross-Pitaevskii

Equation with a Time-Dependent Harmonic Potential and Interatomic Interaction

Authors: U. Al Khawaja

Categories: cond-mat.other

\\

We derive exact solitonic solutions of the one-dimensional time-dependent

Gross-Pitaevskii equation with time-dependent strengths of the harmonic

external potential and the interatomic interaction. The time-dependence of the

external potential and interatomic interaction are given in terms of a general

function of time. For an oscillating strength of the external potential, the

solutions correspond to breathing single and multiple solitons. The amplitude

and frequency of the oscillating potential can be used to control the dynamics

of the center of mass of the solitons. For certain values of these parameters,

the solitons can be {\it trapped} at the center of the harmonic potential.

\\ ( http://arxiv.org/abs/0706.2705 , 774kb)

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arXiv:0706.2744

Date: Tue, 19 Jun 2007 12:16:29 GMT (399kb,D)

Title: Dynamical instabilities of Bose-Einstein condensates at the band-edge in

one-dimensional optical lattices

Authors: Andrew J. Ferris, Matthew J. Davis, Reece W. Geursen, P. Blair Blakie,

Andrew C. Wilson

Categories: cond-mat.other

Comments: 16 pages, 19 figures

\\

We report on experiments that demonstrate dynamical instability in a

Bose-Einstein condensate at the band-edge of a one-dimensional optical lattice.

The instability manifests as rapid depletion of the condensate and conversion

to a thermal cloud. We consider the collisional processes that can occur in

such a system, and perform numerical modeling of the experiments using both a

mean-field and beyond mean-field approach. We compare our numerical results to

the experimental data, and find that the Gross-Pitaevskii equation is not able

to describe this experiment. Our beyond mean-field approach, known as the

truncated Wigner method, allows us to make quantitative predictions for the

processes of parametric growth and thermalization that are observed in the

laboratory, and we find good agreement with the experimental results.

\\ ( http://arxiv.org/abs/0706.2744 , 399kb)

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arXiv:0706.2781

Date: Tue, 19 Jun 2007 13:03:05 GMT (263kb)

Title: Degenerate Bose-Bose mixture in a 3D optical lattice

Authors: J. Catani, L. De Sarlo, G. Barontini, F. Minardi and M. Inguscio

Categories: cond-mat.other

\\

We produce a quantum degenerate mixture of $^{87}$Rb and $^{41}$K bosonic

species in a 3-dimensional optical lattice. Raising the lattice barriers, we

observe the superfluid to Mott insulator transition of the heavier $^{87}$Rb in

presence of a minor fraction of $^{41}$K. Due to the repulsive interspecies

interaction, the loss of phase coherence normally associated with the onset of

the Mott insulator is shifted towards shallower lattice depths. We compare our

results with similar findings reported for Fermi-Bose mixtures and discuss the

interpretation scenarios proposed to date. We argue that the explanation may be

linked to the increased effective mass due to the interspecies interactions.

\\ ( http://arxiv.org/abs/0706.2781 , 263kb)

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arXiv:0706.2826

Date: Tue, 19 Jun 2007 16:23:43 GMT (106kb)

Title: Barrier transmission for the one-dimensional nonlinear Schr\"odinger

equation: resonances and transmission profiles

Authors: K. Rapedius, H. J. Korsch

Categories: cond-mat.other

Comments: 9 pages, 6 figures, 1 table

\\

The stationary nonlinear Schr\"odinger equation (or Gross-Pitaevskii

equation) for one-dimensional potential scattering is studied. The nonlinear

transmission function shows a distorted profile, which differs from the

Lorentzian one found in the linear case. This nonlinear profile function is

analyzed and related to Siegert type complex resonances. It is shown, that the

characteristic nonlinear profile function can be conveniently described in

terms of skeleton functions depending on a few instructive parameters. We also

extend the Siegert method for calculating resonances, which provides a

convenient recipe for calculating nonlinear resonances. Applications to a

double Gaussian barrier and a square well potential illustrate our analysis.

\\ ( http://arxiv.org/abs/0706.2826 , 106kb)

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arXiv:0706.2833

Date: Tue, 19 Jun 2007 17:52:14 GMT (72kb)

Title: Bose-Einstein Condensation in the Relativistic Ideal Bose Gas

Authors: M. Grether, M. de Llano, and George A. Baker Jr

Categories: cond-mat.supr-con

Comments: 10 pages, 4 figures

\\

The Bose-Einstein condensation (BEC) critical temperature in a relativistic

ideal Bose gas of identical bosons, with and without the antibosons expected to

be pair-produced abundantly at sufficiently hot temperatures, is exactly

calculated for all boson number-densities, all boson point rest masses, and all

temperatures. The Helmholtz free energy at the critical BEC temperature is

found to be lower, thus implying that the omission of antibosons always leads

to the computation of a metastable state.

\\ ( http://arxiv.org/abs/0706.2833 , 72kb)

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arXiv:0706.2841

Date: Tue, 19 Jun 2007 17:20:02 GMT (26kb)

Title: Doppler controlled dynamics of a mirror attached to a spring

Authors: Khaled Karrai, Ivan Favero, Constanze Metzger

Categories: cond-mat.other

Comments: 4 pages, 1 figure

\\

A laser beam directed at a mirror attached onto a flexible mount extracts

thermal energy from its mechanical Brownian motion by Doppler effect. For a

normal mirror the efficiency of this Doppler cooling is very weak and masked by

laser shot-noise. We find that it can become very efficient using a Bragg

mirror at the long wavelength edge of its band stop. The opposite effect of

cooling opens new routes for optical pumping of mechanical systems: a laser

pointing at a Bragg mirror and tuned at its short wavelength edge induces

amplification of the vibrational excitation of the mirror leading eventually to

its self-oscillation. This new effects rely on the strong dependency of the

Bragg mirror reflectivity on the wavelength.

\\ ( http://arxiv.org/abs/0706.2841 , 26kb)

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arXiv:0706.2855

Date: Tue, 19 Jun 2007 18:26:18 GMT (23kb)

Title: Crystalline phase of strongly interacting Fermi mixtures

Authors: D.S. Petrov, G.E. Astrakharchik, D.J. Papoular, C. Salomon, G.V.

Shlyapnikov

Categories: cond-mat.stat-mech

Comments: 5 pages, 1 color figure

Report-no: NSF-KITP-07-132

\\

We show that the system of weakly bound molecules of heavy and light

fermionic atoms is characterized by a long-range intermolecular repulsion and

can undergo a gas-crystal quantum transition if the mass ratio exceeds a

critical value. For the critical mass ratio above 100 obtained in our

calculations, this crystalline order can be observed as a superlattice in an

optical lattice for heavy atoms with a small filling factor. We also find that

this novel system is sufficiently stable with respect to molecular relaxation

into deep bound states and to the process of trimer formation.

\\ ( http://arxiv.org/abs/0706.2855 , 23kb)

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arXiv:0706.2830

Date: Tue, 19 Jun 2007 16:29:11 GMT (116kb)

Title: A new look at the problem of gauge invariance in quantum field theory

Authors: Dan Solomon

Categories: quant-ph

Comments: Accepted by Physica Scripta. 27 pages

Journal-ref: Physica Scripta 76 (2007) 64-71

\\

Quantum field theory is assumed to be gauge invariant. However it is well

known that when certain quantities are calculated using perturbation theory the

results are not gauge invariant. The non-gauge invariant terms have to be

removed in order to obtain a physically correct result. In this paper we will

examine this problem and determine why a theory that is supposed to be gauge

invariant produces non-gauge invariant results.

\\ ( http://arxiv.org/abs/0706.2830 , 116kb)

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arXiv:0706.2672

Date: Mon, 18 Jun 2007 22:10:19 GMT (94kb)

Title: Using Three-Body Recombination to Extract Electron Temperatures of

Ultracold Plasmas

Authors: R. S. Fletcher, X. L. Zhang, and S. L. Rolston

Categories: physics.atom-ph physics.plasm-ph

Comments: 5 pages, 3 figures

\\

Three-body recombination, an important collisional process in plasmas,

increases dramatically at low electron temperatures, with an accepted scaling

of T_e^-9/2. We measure three-body recombination in an ultracold neutral xenon

plasma by detecting recombination-created Rydberg atoms using a

microwave-ionization technique. With the accepted theory (expected to be

applicable for weakly-coupled plasmas) and our measured rates we extract the

plasma temperatures, which are in reasonable agreement with previous

measurements early in the plasma lifetime. The resulting electron temperatures

indicate that the plasma continues to cool to temperatures below 1 K.

\\ ( http://arxiv.org/abs/0706.2672 , 94kb)

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arXiv:0706.2849

Date: Tue, 19 Jun 2007 17:59:27 GMT (332kb)

Title: The coupling of the X$^{1}\Sigma ^{+}$ and a$^{3}\Sigma ^{+}$ states of

KRb

Authors: A. Pashov, O. Docenko, M. Tamanis, R. Ferber, H. Knoeckel, E. Tiemann

Categories: physics.atom-ph

Comments: 14 pages, 5 figures

\\

A comprehensive study of the electronic states at the 4s+5s asymptote in KRb

is presented. Abundant spectroscopic data on the \astate state were collected

by Fourier-transform spectroscopy which allow to determine an accurate

experimental potential energy curve up to 14.8 \AA . The existing data set (C.

Amiot et al. J. Chem. Phys. 112, 7068 (2000)) on the ground state \Xstate was

extended by several additional levels lying close to the atomic asymptote. In a

coupled channels fitting routine complete molecular potentials for both

electronic states were fitted. Along with the line frequencies of the molecular

transitions, recently published positions of Feshbach resonances in $^{40}$K

and $^{87}$Rb mixtures (F. Ferlaino et al. Phys. Rev. A 74, 039903 (2006)) were

included in the fit. This makes the derived potential curves capable for an

accurate description of observed cold collision features so far. Predictions of

scattering lengths and Feshbach resonances in other isotopic combinations are

reported.

\\ ( http://arxiv.org/abs/0706.2849 , 332kb)

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arXiv:0706.2869

Date: Wed, 20 Jun 2007 19:50:18 GMT (100kb)

Title: Supercurrent survival under Rosen-Zener quench of hard core bosons

Authors: I. Klich, C. Lannert, G. Refael

Categories: cond-mat.other

\\

We study the survival of super-currents in a system of impenetrable bosons

subject to a quantum quench from its critical superfluid phase to an insulating

phase. We show that the evolution of the current when the quench follows a

Rosen-Zener profile is exactly solvable. This allows us to analyze a quench of

arbitrary rate, from a sudden destruction of the superfluid to a slow opening

of a gap. The decay and oscillations of the current are analytically derived,

and studied numerically along with the momentum distribution after the quench.

In the case of small supercurrent boosts $\nu$, we find that the current

surviving at long times is proportional to $\nu^3$.

\\ ( http://arxiv.org/abs/0706.2869 , 100kb)

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arXiv:0706.2887

Date: Wed, 20 Jun 2007 19:13:49 GMT (43kb)

Title: Casimir effect in a one-dimensional gas of free fermions

Authors: Eugene B. Kolomeisky, Joseph P. Straley, and Michael Timmins

Categories: cond-mat.mes-hall

Comments: 11 pages, 5 figures

\\

The standard computations of the electromagnetic Casimir effect as a response

of the vacuum to introduction of boundaries are not fully satisfactory since

quantum electrodynamics is an effective low-energy theory that requires

regularization in order to handle the ultraviolet divergent vacuum energies

appearing in the calculation. Following a proposal due to Volovik (2003), the

validity of such an approach is tested by rigorous analysis of an analog

Casimir effect in an exactly-solvable model of a one-dimensional

non-relativistic spinless gas of free fermions whose ground state plays the

role of the vacuum. Specifically, we consider fermions confined to a segment

whose ends are subject to all possible combinations of free or fixed end

boundary conditions in the presence of a nearly-impenetrable partition dividing

the segment into two compartments. As a function of the position of the

partition, the Casimir interaction is found to be a bounded

piecewise-continuous oscillatory function whose maxima, the points of force

discontinuity, correspond to resonant tunneling across the partition. In the

limit of macroscopic occupancy of the compartments, the distance between

nearest extrema of the Casimir interaction is half the bulk interparticle

spacing while the phase of the oscillation is set by the boundary conditions at

the segment ends. The lower envelope of this function reproduces a

regularization-based prediction and corresponds to the approximation that

ignores the discreteness of the underlying particles. Additionally we confirm

the result of a recent calculation which employed an effective low-energy

theory with a cutoff to find the Casimir interaction between two strong

well-separated impurities placed in a Fermi gas.

\\ ( http://arxiv.org/abs/0706.2887 , 43kb)

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arXiv:0706.3036

Date: Wed, 20 Jun 2007 18:03:37 GMT (108kb)

Title: The Hubbard model: bosonic excitations and zero-frequency constants

Authors: Adolfo Avella, Ferdinando Mancini

Categories: cond-mat.str-el cond-mat.supr-con

Journal-ref: Physica C 408, 287 (2004)

DOI: 10.1016/j.physc.2004.02.156

\\

A fully self-consistent calculation of the bosonic dynamics of the Hubbard

model is developed within the Composite Operator Method. From one side we

consider a basic set of fermionic composite operators (Hubbard fields) and

calculate the retarded propagators. On the other side we consider a basic set

of bosonic composite operators (charge, spin and pair) and calculate the causal

propagators. The equations for the Green's functions (GF) (retarded and

causal), studied in the polar approximation, are coupled and depend on a set of

parameters not determined by the dynamics. First, the pair sector is

self-consistently solved together with the fermionic one and the zero-frequency

constants (ZFC) are calculated not assuming the ergodic value, but fixing the

representation of the GF in such a way to maintain the constrains required by

the algebra of the composite fields. Then, the scheme to compute the charge and

spin sectors, ZFCs included, is given in terms of the fermionic and pair

correlators.

\\ ( http://arxiv.org/abs/0706.3036 , 108kb)

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arXiv:0706.3072

Date: Thu, 21 Jun 2007 19:36:54 GMT (569kb)

Title: Efficient vibrational state coupling in an optical tilted-washboard

potential via multiple spatial translations

Authors: Samansa Maneshi, Jalani F. Kanem, Chao Zhuang, Matt Partlow, and

Aephraim M. Steinberg

Categories: quant-ph

Comments: 12 pages, 16 figures

\\

We measure the application of simple and compound pulses consisting of

time-dependent spatial translations to coupling vibrational states of cold 85Rb

atoms in a 1D optical lattice. The lattice is oriented vertically, leading to a

tilted-washboard potential analogous to those encountered is condensed-matter

systems. Experimentally, we find that a square pulse consisting of lattice

displacements and a delay is more efficient than single-step and Gaussian

pulses. Numerical calculations are in strong agreement with our experimental

results and show the superiority of the square pulse to the single-step pulse

for all lattice depths and to the Gaussian pulse for lattice depths greater

than 7 lattice recoil energies. We also compare the effectiveness of these

pulses for reviving oscillations of atoms in vibrational superposition states

using the pulse-echo technique. We find that the square and Gaussian pulses

result in higher echo amplitudes than the single-step pulse. In addition, we

show numerically that the vibrational state coupling due to such lattice

manipulations is more efficient in shallow lattices than in deep lattices. The

coupling probability for an optimized single-step pulse approaches 1/e as the

depth goes to infinity (harmonic-oscillator limit), while in shallow lattices

with large anharmonicity, the coupling probability reaches a maximum value of

0.51 for a lattice depth of 5 recoil energies. For square and Gaussian pulses

the coupling in the lattice is even stronger, reaching maxima of 0.64 at 6

recoil energies and 0.67 at 5 recoil energies, respectively.

\\ ( http://arxiv.org/abs/0706.3072 , 569kb)

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\\

arXiv:0706.3133

Date: Thu, 21 Jun 2007 12:07:33 GMT (117kb)

Title: Tunable photonic band gaps with coherently driven atoms in optical

lattices

Authors: David Petrosyan

Categories: quant-ph

\\

Optical lattice loaded with cold atoms can exhibit a tunable photonic band

gap for a weak probe field under the conditions of electromagnetically induced

transparency. This system possesses a number of advantageous properties,

including reduced relaxation of Raman coherence and the associated probe

absorption, and simultaneous enhancement of the index modulation and the

resulting reflectivity of the medium. This flexible system has a potential to

serve as a testbed of various designs for the linear and nonlinear photonic

band gap materials at a very low light level and can be employed for realizing

deterministic entanglement between weak quantum fields.

\\ ( http://arxiv.org/abs/0706.3133 , 117kb)

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The replacements:

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arXiv:0704.0712

replaced with revised version Fri, 15 Jun 2007 13:41:23 GMT (138kb)

Title: Interference effects in above-threshold ionization from diatomic

molecules: determining the internuclear separation

Authors: H. Hetzheim, C. Figueira de Morisson Faria, and W. Becker

Categories: physics.atom-ph

Comments: 10 pages, 8 figures; discussions slightly modified and an additional

figure inserted for clarity

\\ ( http://arxiv.org/abs/0704.0712 , 138kb)

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\\

arXiv:cond-mat/0603162

replaced with revised version Mon, 18 Jun 2007 09:08:06 GMT (165kb)

Title: Bose-Fermi mixtures in an optical lattice

Authors: K. Sengupta, N. Dupuis, and P. Majumdar

Categories: cond-mat.str-el

Comments: Final version; Aceepted for publication in PRA

\\ ( http://arxiv.org/abs/cond-mat/0603162 , 165kb)

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\\

arXiv:cond-mat/0608689

replaced with revised version Sat, 16 Jun 2007 01:03:34 GMT (60kb)

Title: BEC-BCS crossover of a trapped Fermi gas without using the local density

approximation

Authors: R. Jauregui, R. Paredes, and G. Toledo Sanchez

Categories: cond-mat.other

Comments: 10 pages, 3 figures, 1 table. This version includes calculations for

all closed shells upto 440 atoms and we explored shorter potential ranges

\\ ( http://arxiv.org/abs/cond-mat/0608689 , 60kb)

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\\

arXiv:cond-mat/0703731

replaced with revised version Mon, 18 Jun 2007 04:54:10 GMT (328kb)

Title: Degenerate Fermi gas in a combined harmonic-lattice potential

Authors: P. B. Blakie, A. Bezett, P. Buonsante

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

Comments: 11 pages, 9 figures

Journal-ref: Phys. Rev. A 75, 063609 (2007)

DOI: 10.1103/PhysRevA.75.063609

\\ ( http://arxiv.org/abs/cond-mat/0703731 , 328kb)

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\\

arXiv:0705.2658

replaced with revised version Tue, 19 Jun 2007 17:42:34 GMT (20kb)

Title: The Josephson effect throughout the BCS-BEC crossover

Authors: A. Spuntarelli, P. Pieri, G.C. Strinati

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

Comments: 4 pages, 3 figures; improved version to appear in Phys. Rev. Lett

\\ ( http://arxiv.org/abs/0705.2658 , 20kb)

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\\

arXiv:cond-mat/0607835

replaced with revised version Mon, 18 Jun 2007 20:36:16 GMT (274kb)

Title: Fermi gas near unitarity around four and two spatial dimensions

Authors: Yusuke Nishida and Dam Thanh Son

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

Comments: 23 pages, 15 figures, revtex4; version to appear in Phys. Rev. A

Report-no: INT-PUB 06-10, TKYNT-06-10

Journal-ref: Phys. Rev. A 75, 063617 (2007)

DOI: 10.1103/PhysRevA.75.063617

\\ ( http://arxiv.org/abs/cond-mat/0607835 , 274kb)

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\\

arXiv:cond-mat/0608321

replaced with revised version Mon, 18 Jun 2007 20:50:04 GMT (127kb)

Title: Unitary Fermi gas at finite temperature in the epsilon expansion

Authors: Yusuke Nishida

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

Comments: 13 pages, 7 figures, revtex4; version to appear in Phys. Rev. A

Report-no: INT-PUB 06-13, TKYNT-06-11

Journal-ref: Phys. Rev. A 75, 063618 (2007)

DOI: 10.1103/PhysRevA.75.063618

\\ ( http://arxiv.org/abs/cond-mat/0608321 , 127kb)

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\\

arXiv:0705.0923

replaced with revised version Tue, 19 Jun 2007 20:52:31 GMT (47kb)

Title: Precise manipulation of a Bose-Einstein condensate using Bragg

interactions

Authors: K. J. Hughes, B. Deissler, J. H. T. Burke and C.A. Sackett

Categories: cond-mat.other

Comments: 5 pages, 3 figures. Revised text, fixed error in figure

\\ ( http://arxiv.org/abs/0705.0923 , 47kb)

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\\

arXiv:cond-mat/0508667

replaced with revised version Wed, 20 Jun 2007 03:36:05 GMT (23kb)

Title: Critical temperature of a trapped Bose gas: comparison of theory and

experiment

Authors: Matthew J. Davis and P. Blair Blakie

Categories: cond-mat.other

Comments: revtex4, four pages, three figures. v2: updated to published version.

Several additions to figures, and better explanations in text in response to

referee comments

Journal-ref: Phys. Rev. Lett. 96, 060404 (2006)

DOI: 10.1103/PhysRevLett.96.060404

\\ ( http://arxiv.org/abs/cond-mat/0508667 , 23kb)

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\\

arXiv:cond-mat/0508674

replaced with revised version Wed, 20 Jun 2007 03:30:32 GMT (18kb)

Title: Calculation of the microcanonical temperature for the classical Bose

field

Authors: Matthew J. Davis and P. Blair Blakie

Categories: cond-mat.other

Comments: revtex4, 10 pages, 1 figure. v2: updated to published version. Fuller

discussion of numerical results, correction of some minor errors

Journal-ref: J. Phys. A 38, 10259 (2005)

DOI: 10.1088/0305-4470/38/48/001

\\ ( http://arxiv.org/abs/cond-mat/0508674 , 18kb)

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\\

arXiv:quant-ph/0701207

replaced with revised version Wed, 20 Jun 2007 12:13:34 GMT (833kb)

Title: Roughness suppression via rapid current modulation on an atom chip

Authors: Jean-Baptiste Trebbia (LCFIO), Carlos Leonardo Garrido Alzar (LCFIO),

Ronald Cornelussen (LCFIO), Christoph I. Westbrook (LCFIO), Isabelle

Bouchoule (LCFIO)

Categories: quant-ph cond-mat.other

Journal-ref: Physical Review Letters (29/01/2007) 4

\\ ( http://arxiv.org/abs/quant-ph/0701207 , 833kb)

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\\

arXiv:0704.1971

replaced with revised version Thu, 21 Jun 2007 17:15:23 GMT (119kb)

Title: Dissipative dynamics of superfluid vortices at non-zero temperatures

Authors: Natalia G. Berloff and Anthony J. Youd

Categories: cond-mat.soft

Comments: 4 pages, 3 figures

\\ ( http://arxiv.org/abs/0704.1971 , 119kb)

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\\

arXiv:0704.2627

replaced with revised version Wed, 20 Jun 2007 20:31:52 GMT (231kb)

Title: Atom-wave diffraction between the Raman-Nath and the Bragg regime:

Effective Rabi frequency, losses, and phase shifts

Authors: Holger Mueller, Sheng-wey Chiow, and Steven Chu

Categories: physics.atom-ph

Comments: New introduction; added references. 22 pages, 10 figures

\\ ( http://arxiv.org/abs/0704.2627 , 231kb)

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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 Fri Jul 06 2007 - 13:21:54 EST

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