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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