Matt's arXiv selection: week ending 5 December 2008

From: Matthew Davis <>
Date: Wed, 07 Jan 2009 22:23:40 +1000

The following message was sent to the matts_arxiv list by Matthew Davis <>

A busy week with 39 preprints and 13 replacements. Look out for the paper that
explains the mathematics of the financial crisis: apparently there are too many
indistinguishable US notes floating around and they have Bose condensed!

Date: Thu, 27 Nov 2008 00:32:38 GMT (843kb)

Title: Extreme tunability of interactions in a $^7$Li Bose-Einstein condensate
Authors: Scott E. Pollack, D. Dries, M. Junker, Y. P. Chen, T. A. Corcovilos,
   and R. G. Hulet
Categories: cond-mat.other
   We use a Feshbach resonance to tune the scattering length a of a
Bose-Einstein condensate of 7Li in the |F = 1, m_F = 1> state. Using the
spatial extent of the trapped condensate we extract a over a range spanning 7
decades from small attractive interactions to extremely strong repulsive
interactions. The shallow zero-crossing in the wing of the Feshbach resonance
enables the determination of a as small as 0.01 Bohr radii. In this regime,
evidence of the weak anisotropic magnetic dipole interaction is obtained by
comparison with different trap geometries.
\\ ( , 843kb)
Date: Thu, 27 Nov 2008 09:51:22 GMT (9kb)

Title: Ferminization of the Luttinger model with short-range interaction
Authors: V. V. Afonin (A. F. Ioffe Institute of the Russian Academy of
   Sciences, Saint Petersburg, Russia), V. Yu. Petrov (Theory Division, Saint
   Petersburg, Nuclear Physics)
Categories: cond-mat.str-el cond-mat.stat-mech
Comments: paper 7 pages
   We present a transformation allowing one to represent the Luttenger model
with short range interacting as a free fermion problem. As well as a
bosonization procedure this approach permits one describe an excitation state
of the model. The electric charge and chirality of the new fermion is
\\ ( , 9kb)
Date: Thu, 27 Nov 2008 10:39:16 GMT (236kb)

Title: Probing the excitation spectrum of nonresonantly pumped polariton
Authors: Michiel Wouters and Iacopo Carusotto
Categories: cond-mat.other
Comments: 7 pages, 5 figures
   We propose a four wave mixing experiment to probe the elementary excitation
spectrum of a non-equilibrium Bose-Einstein condensate of exciton-polaritons
under non-resonant pumping. Analytical calculations based on mean-field theory
show that this method is able to reveal the characteristic negative energy
feature of the Bogoliubov dispersion. Numerical simulations including the
finite spatial profile of the excitation laser spot and a weak disorder confirm
the practical utility of the method for realistic condensates.
\\ ( , 236kb)
Date: Thu, 27 Nov 2008 11:18:04 GMT (52kb)

Title: Phases and collective modes of hardcore Bose-Fermi mixture in an optical
Authors: S. Sinha and K. Sengupta
Categories: cond-mat.str-el
Comments: 10 pages 6 Figs v1
   We obtain the phase diagram of a Bose-Fermi mixture of hardcore spinless
Bosons and spin-polarized Fermions with nearest neighbor intra-species
interaction and on-site inter-species repulsion in an optical lattice at
half-filling using a slave-boson mean-field theory. We show that such a system
can have four possible phases which are a) supersolid Bosons coexisting with
Fermions in the Mott state, b) Mott state of Bosons coexisting with Fermions in
a metallic or charge-density wave state, c) a metallic Fermionic state
coexisting with superfluid phase of Bosons, and d) Mott insulating state of
Fermions and Bosons. We chart out the phase diagram of the system and provide
analytical expressions for the phase boundaries within mean-field theory. We
demonstrate that the transition between these phases are generically first
order with the exception of that between the supersolid and the Mott states
which is a continuous quantum phase transition. We also obtain the low-energy
collective excitations of the system in these phases. Finally, we study the
particle-hole excitations in the Mott insulating phase and use it to determine
the dynamical critical exponent $z$ for the supersolid-Mott insulator
transition. We discuss experiments which can test our theory.
\\ ( , 52kb)
Date: Thu, 27 Nov 2008 15:46:06 GMT (673kb)

Title: Stochastic classical field model for polariton condensates
Authors: Michiel Wouters and Vincenzo Savona
Categories: cond-mat.other
Comments: 10 pages, 7 figures
   We use the truncated Wigner approximation to derive stochastic classical
field equations for the description of polariton condensates. Our equations are
shown to reduce to the Boltzmann equation in the limit of low polariton
density. Monte Carlo simulations are performed to analyze the momentum
distribution and the first and second order coherence when the particle density
is varied across the condensation threshold.
\\ ( , 673kb)
Date: Fri, 28 Nov 2008 11:57:46 GMT (21kb)

Title: Hubbard model calculations of phase separation in optical lattices
Authors: H. Heiselberg
Categories: cond-mat.supr-con cond-mat.str-el
   Antiferromagnetic, Mott insulator, d-wave and gossamer superfluid phases are
calculated for 2D square lattices from the extended Hubbard (t-J-U) model using
the Gutzwiller projection method and renormalized mean field theory. Phase
separation between antiferromagnetic and d-wave superfluid phases is found near
half filling when the on-site repulsion exceeds $U\ga7.3t$, and coincides with
a first order transition in the double occupancy. Phase separation is thus
predicted for 2D optical lattices with ultracold Fermi atoms whereas it is
inhibited in cuprates by Coulomb frustration which instead may lead to stripes.
In a confined optical lattice the resulting density distribution is
discontinuous an with extended Mott plateau which enhances the
antiferromagnetic phase but suppresses the superfluid phase. Observation of
Mott insulator, antiferromagnetic, stripe and superfluid phases in density and
momentum distributions and correlations is discussed.
\\ ( , 21kb)
Date: Thu, 20 Nov 2008 20:39:04 GMT (1009kb)

Title: Coherent Patterning of Matter Waves with Subwavelength Localization
Authors: J. Mompart, V. Ahufinger, G. Birkl
Categories: quant-ph cond-mat.other physics.optics
Comments: 5 pages, 5 figures
   We introduce the Subwavelength Localization via Adiabatic Passage (SLAP)
technique to coherently achieve state-selective patterning and addressing of
matter waves. The SLAP technique consists in coupling two partially overlapping
and spatially structured laser fields to three internal levels of the matter
wave yielding state-selective localization at those positions where the
adiabatic passage process does not occur. We show that by means of this
technique matter wave localization down to the single nanometer can be
achieved. We analyze in detail the potential implementation of the SLAP
technique for nano-lithography with an atomic beam of metastable Ne* and for
coherent patterning of a two-component 87Rb Bose-Einstein condensate.
\\ ( , 1009kb)
Date: Thu, 27 Nov 2008 13:51:24 GMT (159kb)

Title: Towards surface quantum optics with Bose-Einstein condensates in
   evanescent waves
Authors: Helmar Bender, Philippe Courteille, Claus Zimmermann, and Sebastian
Categories: quant-ph
   We present a surface trap which allows for studying the coherent interaction
of ultracold atoms with evanescent waves. The trap combines a magnetic Joffe
trap with a repulsive evanescent dipole potential. The position of the magnetic
trap can be controlled with high precision which makes it possible to move
ultracold atoms to the surface of a glass prism in a controlled way. The
optical potential of the evanescent wave compensates for the strong attractive
van der Waals forces and generates a potential barrier at only a few hundred
nanometers from the surface. The trap is tested with Rb Bose-Einstein
condensates (BEC), which are stably positioned at distances from the surfaces
below one micrometer.
\\ ( , 159kb)
Date: Thu, 27 Nov 2008 19:09:35 GMT (163kb)

Title: Superfluidity of a perfect quantum crystal
Authors: V.A. Golovko
Categories: quant-ph
Comments: 20 pages with 2 figures
   In recent years, experimental data were published which point to the
possibility of the existence of superfluidity in solid helium. To investigate
this phenomenon theoretically we employ a hierarchy of equations for reduced
density matrices which describes a quantum system that is in thermodynamic
equilibrium below the Bose-Einstein condensation point, the hierarchy being
obtained earlier by the author. It is shown that the hierarchy admits solutions
relevant to a perfect crystal (immobile) in which there is a frictionless flow
of atomes, which testifies to the possibility of superfluidity in solids. The
solutions are studied with the help of the bifurcation method and some their
peculiarities are found out. We discuss also various physical aspects of the
problem, among them experimental ones.
\\ ( , 163kb)
Date: Thu, 27 Nov 2008 21:05:22 GMT (166kb)

Title: Ultracold polar molecules near quantum degeneracy
Authors: S. Ospelkaus, K.-K. Ni, M. H. G. de Miranda, B. Neyenhuis, D. Wang, S.
   Kotochigova, P. S. Julienne, D. S. Jin, and J. Ye
Categories: physics.atom-ph
   We report the creation and characterization of a near quantum-degenerate gas
of polar $^{40}$K-$^{87}$Rb molecules in their absolute rovibrational ground
state. Starting from weakly bound heteronuclear KRb Feshbach molecules, we
implement precise control of the molecular electronic, vibrational, and
rotational degrees of freedom with phase-coherent laser fields. In particular,
we coherently transfer these weakly bound molecules across a 125 THz frequency
gap in a single step into the absolute rovibrational ground state of the
electronic ground potential. Phase coherence between lasers involved in the
transfer process is ensured by referencing the lasers to two single components
of a phase-stabilized optical frequency comb. Using these methods, we prepare a
dense gas of $4\cdot10^4$ polar molecules at a temperature below 400 nK. This
fermionic molecular ensemble is close to quantum degeneracy and can be
characterized by a degeneracy parameter of $T/T_F=3$. We have measured the
molecular polarizability in an optical dipole trap where the trap lifetime
gives clues to interesting ultracold chemical processes. Given the large
measured dipole moment of the KRb molecules of 0.5 Debye, the study of quantum
degenerate molecular gases interacting via strong dipolar interactions is now
within experimental reach.
\\ ( , 166kb)

Date: Fri, 28 Nov 2008 21:20:51 GMT (2124kb)

Title: Ultracold gases far from equilibrium
Authors: Thomas Gasenzer
Categories: cond-mat.other
Comments: 59 pages, 26 figures; Compiled from notes for lectures held at 46.
   Internationale Universitaetswochen fuer Theoretische Physik 2008 in
   Schladming, Austria. To be published in Eur. Phys. J. Special Topics
   Ultracold atomic quantum gases belong to the most exciting challenges of
modern physics. Their theoretical description has drawn much from classical
field equations. These mean-field approximations are in general reliable for
dilute gases in which the atoms collide only rarely with each other, and for
situations where the gas is not too far from thermal equilibrium. With
present-day technology it is, however, possible to drive and observe a system
far away from equilibrium. Functional quantum field theory provides powerful
tools to achieve both, analytical understanding and numerical computability,
also in higher dimensions, of far-from-equilibrium quantum many-body dynamics.
In the article, an outline of these approaches is given, including methods
based on the two-particle irreducible effective action as well as on
renormalisation-group theory. Their relation to near-equilibrium kinetic theory
is discussed, and the distinction between quantum and classical statistical
fluctuations is shown to naturally emerge from the functional-integral
description. Example applications to the evolution of an ultracold atomic Bose
gas in one spatial dimension underline the power of the methods. The article is
compiled from the notes for lectures held at 46. Internationale
Universitaetswochen fuer Theoretische Physik 2008 in Schladming, Austria.
\\ ( , 2124kb)

Date: Sat, 29 Nov 2008 15:19:00 GMT (1461kb)

Title: Impurity crystal in a Bose-Einstein condensate
Authors: David C. Roberts and Sergio Rica
Categories: cond-mat.stat-mech cond-mat.other
Comments: 5 pages, 3 color figures; Accepted to Phys. Rev. Lett
   We investigate the behavior of impurity fields immersed in a larger
condensate field in 1, 2, and 3 dimensions. We discuss the localization of a
single impurity field within a condensate and note the effects of surface
energy. We derive the functional form of the attractive interaction between two
impurities due to mediation from the condensate. Generalizing the analysis to
$N$ impurity fields, we show that within various parameter regimes a crystal of
impurity fields can form spontaneously in the condensate. Finally, the system
of condensate and crystallized impurity structure is shown to have nonclassical
rotational inertia, which is characteristic of superfluidity, i.e. the system
can be seen to exhibit supersolid behavior.
\\ ( , 1461kb)

Date: Mon, 1 Dec 2008 08:08:47 GMT (61kb)

Title: Collective modes of trapped Fermi gases with in-medium interaction
Authors: S.Chiacchiera, T.Lepers, M.Urban, D.Davesne
Categories: cond-mat.other
Comments: 17 pages
   Due to Pauli blocking of intermediate states, the scattering matrix (or T
matrix) of two fermionic atoms in a Fermi gas becomes different from that of
two atoms in free space. This effect becomes particularly important near a
Feshbach resonance, where the interaction in free space is very strong but
becomes effectively suppressed in the medium. We calculate the in-medium T
matrix in ladder approximation and study its effects on the properties of
collective modes of a trapped gas in the normal-fluid phase. We introduce the
in-medium interaction on both sides of the Boltzmann equation, namely in the
calculation of the mean field and in the calculation of the collision rate.
With mean field inclusion, we can considerably improve the agreement with
measured temperature dependence of frequency and damping rate of the scissors
mode. In addition, we compute frequencies and damping rates of the radial
quadrupole and compression modes.
\\ ( , 61kb)

Date: Mon, 1 Dec 2008 09:26:43 GMT (228kb)

Title: Bose-Einstein condensate in a quartic potential: Static and Dynamic
Authors: G. K. Chaudhary, Amit K Chattopadhyay, R. Ramakumar
Categories: cond-mat.other cond-mat.stat-mech
Comments: 10 pages, including figures
   In this paper, we present a theoretical study of a Bose-Einstein condensate
of interacting bosons in a quartic trap in one, two, and three dimensions.
Using Thomas-Fermi approximation, suitably complemented by numerical solutions
of the Gross-Pitaevskii equation, we study the ground sate condensate density
profiles, the chemical potential, the effects of cross-terms in the quartic
potential, temporal evolution of various energy components of the condensate,
and width oscillations of the condensate. Results obtained are compared with
corresponding results for a bose condensate in a harmonic confinement.
\\ ( , 228kb)

Date: Mon, 1 Dec 2008 11:03:02 GMT (835kb)

Title: Drag force on an oscillating object in quantum turbulence
Authors: Shoji Fujiyama and Makoto Tsubota
Categories: cond-mat.other
Comments: 7 pages, 5 figures, 1 table
   This paper reports results of the computation of the drag force exerted on an
oscillating object in quantum turbulence in superfluid $^4$He.
   The drag force is calculated on the basis of numerical simulations of quantum
turbulent flow about the object. The drag force is proportional to the square
of the magnitude of the oscillation velocity, which is similar to that in
classical turbulence at high Reynolds number. The drag coefficient is also
calculated, and its value is found to be of the same order as that observed in
previous experiments. The correspondence between quantum and classical
turbulence is further clarified by examining the turbulence created by
oscillating objects.
\\ ( , 835kb)

Date: Mon, 1 Dec 2008 12:13:16 GMT (1756kb)

Title: Ferrofluidity in a two-component dipolar Bose-Einstein Condensate
Authors: Hiroki Saito, Yuki Kawaguchi, Masahito Ueda
Categories: cond-mat.other
Comments: 4 pages, 6 figures
   It is shown that the interface in a two-component Bose-Einstein condensate
(BEC) in which one component exhibits a dipole-dipole interaction spontaneously
forms patterns similar to those formed in a magnetic liquid subject to a
magnetic field. A hexagonal pattern, hysteretic behavior, and soliton-like
structure are numerically demonstrated. A phenomenon similar to the
labyrinthine instability is also found. These phenomena may be realized using a
52Cr BEC. The periodic density modulation in the superfluid ground state offers
evidence of supersolidity.
\\ ( , 1756kb)

Date: Mon, 1 Dec 2008 20:47:06 GMT (140kb)

Title: Shining a Light on Bose--Hubbard Mixtures
Authors: M. J. Bhaseen, M. Hohenadler, A. O. Silver, B. D. Simons
Categories: cond-mat.str-el
Comments: 6 pages, 3 figures
   Motivated by recent experiments on cold atomic gases in ultra high finesse
optical cavities, we consider the problem of a two-band Bose--Hubbard model
coupled to quantum light. Photoexcitation promotes carriers between the bands
and we study the non-trivial interplay between Mott insulating behavior and
superfluidity. The model displays a global U(1) X U(1) symmetry which supports
the coexistence of Mott insulating and superfluid phases, and yields a rich
phase diagram with multicritical points. This symmetry property is shared by
several other problems of current experimental interest, including
two-component Bose gases in optical lattices, and the bosonic BEC-BCS crossover
problem for atom-molecule mixtures induced by a Feshbach resonance. We
corroborate our findings by numerical simulations.
\\ ( , 140kb)

Date: Mon, 1 Dec 2008 14:30:35 GMT (30kb)

Title: End-to-end entanglement in Bose-Hubbard chains
Authors: Jose Reslen and Sougato Bose
Categories: quant-ph
Comments: 4 pages, 4 figures
   We study the ground state as well as the dynamics of chains of bosons with
local interaction and nearest-neighbour exchange using numerical techniques
based on renormalization group methods. We explore the development of
entanglement between the sites at the ends of such chains as mechanisms are
invoked to concentrate population in these sites. We find that long-range
entanglement arises in chains with strong repulsion constants in the
intermediate sites, both in ground state and through non-equilibrium dynamics.
Additionally, it is shown that entanglement between the end sites can be made
to increase above their ground state values by adding a perturbation.
\\ ( , 30kb)

Date: Sat, 29 Nov 2008 16:52:44 GMT (1281kb,D)

Title: All-optical 3D atomic loops generated with Bessel light fields
Authors: K. Volke-Sepulveda and R. Jauregui
Categories: physics.atom-ph physics.optics
Comments: 13 pages, 9 figures
   The propagation invariance of Bessel beams as well as their transversal
structure are used to perform a comparative analysis of their effect on cold
atoms for four different configurations and combinations thereof. We show that,
even at temperatures for which the classical description of the atom center of
mass motion is valid, the interchange of momentum, energy and orbital angular
momentum between light and atoms yields efficient tools for all-optical
trapping, transporting and, in general, manipulating the state of motion of
cold atoms.
\\ ( , 1281kb)

Date: Mon, 1 Dec 2008 07:01:46 GMT (58kb)

Title: Measurement of the quadratic Zeeman shift of ^{85}Rb hyperfine sublevels
   using stimulated Raman transitions
Authors: Run-Bing Li, Lin Zhou, Jin Wang, Ming-Sheng Zhan
Categories: physics.atom-ph
   We demonstrate a technique for directly measuring the quadratic Zeeman shift
using stimulated Raman transitions.The quadratic Zeeman shift has been measured
yielding [delta][nju] = 1296.8 +/-3.3 Hz/G^{2} for magnetically insensitive
sublevels (5S1/2, F = 2,mF = 0 -> 5S1/2, F = 3,mF = 0) of ^{85}Rb by
compensating the magnetic eld and cancelling the ac Stark shift. We also
measured the cancellation ratio of the differential ac Stark shift due to the
imbalanced Raman beams by using two pairs of Raman beams ([sigma]^{+},
[sigma]^{+}) and it is 1:3.67 when the one-photon detuning is 1.5 GHz in the
\\ ( , 58kb)

Date: Mon, 1 Dec 2008 10:59:40 GMT (494kb)

Title: Threshold of a Photonic Random Laser with Cold Atoms
Authors: Luis S. Froufe-P\'erez, William Guerin (INLN), R\'emi Carminati
   (LPEM), Robin Kaiser (INLN)
Categories: physics.atom-ph physics.optics
   We address the problem of achieving a photonic random laser with a cloud of
cold atoms, in which gain and scattering are provided by the same atoms. The
lasing threshold can be defined using the on-resonance optical thickness b0 as
a single critical parameter. We predict the threshold quantitatively, as well
as power and frequency of the emitted light, using two different light
transport models and the atomic polarizability of a strongly-pumped two-level
atom. We find a critical b0 on the order of 300, which is within reach of
state-of-the-art cold-atom experiments. Interestingly, we find that random
lasing can already occur in a regime of relatively low scattering.
\\ ( , 494kb)

Date: Tue, 2 Dec 2008 12:49:52 GMT (368kb)

Title: Dynamical formation and interaction of bright solitary waves and
   solitons in the collapse of Bose-Einstein condensates with attractive
Authors: B.J. Dabrowska-Wuester, S. Wuester and M.J. Davis
Categories: cond-mat.other
Comments: 14 pages, 5 figures
   We model the dynamics of formation of multiple, long-lived, bright solitary
waves in the collapse of Bose-Einstein condensates with attractive interactions
as studied in the experiment of Cornish et al. [Phys. Rev. Lett. 96 (2006)
170401]. Using both mean-field and quantum field simulation techniques, we find
that while a number of separated wave packets form as observed in the
experiment, they do not have a repulsive \pi phase difference that has been
previously inferred. We observe that the inclusion of quantum fluctuations
causes soliton dynamics to be predominantly repulsive in one dimensional
simulations independent of their initial relative phase. However, indicative
three-dimensional simulations do not support this conclusion and in fact show
that quantum noise has a negative impact on bright solitary wave lifetimes.
Finally, we show that condensate oscillations, after the collapse, may serve to
deduce three-body recombination rates, and that the remnant atom number may
still exceed the critical number for collapse for as long as three seconds
independent of the relative phases of the bright solitary waves.
\\ ( , 368kb)

Date: Tue, 2 Dec 2008 20:46:21 GMT (83kb)

Title: Coherent pumping of a Mott insulator: Fermi golden rule versus Rabi
Authors: Fabian Hassler and Sebastian D. Huber
Categories: cond-mat.str-el cond-mat.other
Comments: 4 pages, 3 figures
   Cold atoms provide a unique arena to study many-body systems far from
equilibrium. Furthermore, novel phases in cold atom systems are conveniently
investigated by dynamical probes pushing the system out of equilibrium. Here,
we discuss the pumping of doubly-occupied sites in a fermionic Mott insulator
by a periodic modulation of the hopping amplitude. We show that deep in the
insulating phase the many-body system can be mapped onto an effective two-level
system which performs coherent Rabi oscillations due to the driving. Coupling
the two-level system to the remaining degrees of freedom renders the Rabi
oscillations damped. We compare this scheme to an alternative description where
the particles are incoherently pumped into a broad continuum.
\\ ( , 83kb)

Date: Tue, 2 Dec 2008 18:07:26 GMT (164kb)

Title: Time evolution of correlations in strongly interacting fermions after a
   quantum quench
Authors: Salvatore R. Manmana, Stefan Wessel, Reinhard M. Noack, and Alejandro
Categories: cond-mat.str-el
Comments: 10 figures, submitted to Phys. Rev. B
   Using the adaptive time-dependent density matrix renormalization group, we
study the time evolution of density correlations of interacting spinless
fermions on a one-dimensional lattice after a sudden change in the interaction
strength. Over a broad range of model parameters, the correlation function
exhibits a characteristic light-cone-like time evolution representative of a
ballistic transport of information. Such behavior is observed both when
quenching an insulator into the metallic region and also when quenching within
the insulating region. However, when a metallic state beyond the quantum
critical point is quenched deep into the insulating regime, no indication for
ballistic transport is observed. Instead, stable domain walls in the density
correlations emerge during the time evolution, consistent with the predictions
of the Kibble-Zurek mechanism.
\\ ( , 164kb)

Date: Mon, 1 Dec 2008 21:00:13 GMT (76kb)

Title: Stimulated Raman adiabatic passage analogs in classical physics
Authors: A. A. Rangelov, N. V. Vitanov, and B. W. Shore
Categories: quant-ph
   Stimulated Raman adiabatic passage (STIRAP) is a well established technique
for producing coherent population transfer in a three-state quantum system. We
here exploit the resemblance between the Schrodinger equation for such a
quantum system and the Newton equation of motion for a classical system
undergoing torque to discuss several classical analogs of STIRAP, notably the
motion of a moving charged particle subject to the Lorentz force of a
quasistatic magnetic field, the orientation of a magnetic moment in a slowly
varying magnetic field, the Coriolis effect and the inertial frame dragging
effect. Like STIRAP, those phenomena occur for counterintuitively ordered field
pulses and are robustly insensitive to small changes in the interaction
\\ ( , 76kb)

Date: Tue, 2 Dec 2008 04:54:58 GMT (634kb)

Title: Photonic Feshbach Resonance
Authors: D.Z. Xu, H. Ian, T. Shi, H. Dong and C.P. Sun
Categories: quant-ph
   Hermann Feshbach predicted fifty years ago that when two atomic nuclei are
scattered within an open entrance channel-- the state observable at infinity,
they may enter an intermediate closed channel -- the locally bounded state of
the nuclei. If the energy of a bound state of in the closed channel is
fine-tuned to match the relative kinetic energy, then the open channel and the
closed channel "resonate", so that the scattering length becomes divergent. We
find that this so-called Feshbach resonance phenomenon not only exists during
the collisions of massive particles, but also emerges during the coherent
transport of massless particles, that is, photons confined in the coupled
resonator arrays \cite{lzhou08}. We implement the open and the closed channels
inside a pair of such arrays, linked by a separated cavity or a tunable qubit.
When a single photon is bounded inside the closed channel by setting the
relevant physical parameters appropriately, the vanishing transmission appears
to display this photonic Feshbach resonance. The general construction can be
implemented through various experimentally feasible solid state systems, such
as the couple defected cavities in photonic crystals. The numerical simulation
based on finite-different time-domain(FDTD) method confirms our conceive about
physical implementation.
\\ ( , 634kb)

Date: Tue, 2 Dec 2008 13:13:19 GMT (43kb)

Title: Interferometry using spinor Bose-Einstein condensates
Authors: R. Vasile, H. Makela, K.-A. Suominen
Categories: quant-ph
Comments: 6 Pages, 1 figure
   We study the time-evolution of an optically trapped spinor Bose-Einstein
condensate under the influence of a dominating magnetic bias field in the
z-direction, and a perpendicular smaller field that couples the spinor states.
We show that if the bias field depends quadratically on time, the relative
phases of the spinor components affect the populations of the final state. This
allows one to measure the differences in the time-evolution of the relative
phases, thereby realizing a multi-arm interferometer in a spinor Bose-Einstein
\\ ( , 43kb)

Date: Wed, 3 Dec 2008 10:22:24 GMT (33kb)

Title: Photon-assisted tunneling in optical lattices: Ballistic transport of
   interacting boson pairs
Authors: Christoph Weiss (LKB - Lhomond), Heinz-Peter Breuer
Categories: cond-mat.other
Comments: 7 pages, 3 figures
   In a recent experiment [PRL 100, 040404 (2008)] an analog of photon-assisted
tunneling has been observed for a Bose-Einstein condensate in an optical
lattice subject to a constant force plus a sinusoidal shaking. Contrary to
previous theoretical predictions, the width of the condensate was measured to
be proportional to the square of the effective tunneling matrix element, rather
than a linear dependence. For a simple model of two interacting bosons in a
one-dimensional optical lattice, both analytical and numerical calculations
indicate that such a transition from a linear to a quadratic dependence can be
interpreted through the ballistic transport and the corresponding exact
dispersion relation of bound boson pairs.
\\ ( , 33kb)
Date: Wed, 3 Dec 2008 21:07:07 GMT (284kb)

Title: Fermion induced superfluid decoherence in the boson Hubbard model on an
   optical lattice
Authors: Roman M. Lutchyn, Sumanta Tewari, S. Das Sarma
Categories: cond-mat.str-el
Comments: 4 pages, 1 eps figure
   We study the phase diagram of a degenerate gas of bosons in an optical
lattice, described by the boson Hubbard Hamiltonian, interacting with
spin-polarized fermions. Virtual transitions of the bosons to the higher Bloch
bands, coupled with the contact interspecies interactions of either sign,
result in an effective increase of the bosonic on-site repulsion. If this
renormalization of the on-site potential is dominant over the fermionic
screening of the boson interactions, superfluid coherence of the Bose-Hubbard
system will be reduced by the fermions. We discuss experimental implications
for cold atomic systems.
\\ ( , 284kb)

Date: Thu, 4 Dec 2008 07:44:50 GMT (574kb)

Title: Spontaneous Radiation and Amplification of Kelvin Waves on Quantized
   Vortices in Bose--Einstein Condensates
Authors: Hiromitsu Takeuchi, Kenichi Kasamatsu, and Makoto Tsubota
Categories: cond-mat.other
Comments: 5 pages, 5 figures
   We propose a new type of Landau instability in trapped Bose-Einstein
condensates by a helically moving environment. In the presence of quantized
vortices, the instability can cause spontaneous radiation and amplification of
Kelvin waves. This study gives the microscopic understanding of the
Donnelly--Glaberson instability which was known as a hydrodynamic instability
in superfluid helium.
   The Donnelly--Glaberson instability can be a powerful tool for observing the
dispersion relation of Kelvin waves, vortex reconnections, and quantum
turbulence in atomic Bose--Einstein condensates.
\\ ( , 574kb)

Date: Thu, 4 Dec 2008 14:43:14 GMT (279kb)

Title: Dynamical properties of dipolar Fermi gases
Authors: T Sogo, L He, T Miyakawa, S Yi, H Lu and H Pu
Categories: cond-mat.other
Comments: 14 pages, 8 figures, submitted to New J. Phys
   We investigate dynamical properties of a one-component Fermi gas with
dipole-dipole interaction between particles. Using a variational function based
on the Thomas-Fermi density distribution in phase space representation, the
total energy is described by a function of deformation parameters in both real
and momentum space. Various thermodynamic quantities of a uniform dipolar Fermi
gas are derived, and then instability of this system is discussed. For a
trapped dipolar Fermi gas, the collective oscillation frequencies are derived
with the energy-weighted sum rule method. The frequencies for the monopole and
quadrupole modes are calculated, and softening against collapse is shown as the
dipolar strength approaches the critical value. Finally, we investigate the
effects of the dipolar interaction on the expansion dynamics of the Fermi gas
and show how the dipolar effects manifest in an expanded cloud.
\\ ( , 279kb)

Date: Thu, 4 Dec 2008 18:21:31 GMT (210kb)

Title: Bose-Einstein condensation of magnons under incoherent pumping
Authors: A.V. Chumak, G.A. Melkov, V.E. Demidov, O. Dzyapko, V.L. Safonov, and
   S.O. Demokritov
Categories: cond-mat.other
   Bose-Einstein condensation in a gas of magnons pumped by an incoherent
pumping source is experimentally studied at room temperature. We demonstrate
that the condensation can be achieved in a gas of bosons under conditions of
incoherent pumping. Moreover, we show the critical transition point is almost
independent of the frequency spectrum of the pumping source and is solely
determined by the density of magnons. The electromagnetic power radiated by the
magnon condensate was found to scale quadratically with the pumping power,
which is in accordance with the theory of Bose-Einstein condensation in magnon
\\ ( , 210kb)
Date: Thu, 4 Dec 2008 16:21:58 GMT (642kb)

Title: Sculpting the Vortex State of a Spinor BEC
Authors: K. C. Wright, L. S. Leslie, A. Hansen, N. P. Bigelow
Categories: cond-mat.other
Comments: 4 pages, 6 figures, accepted to PRL
   We use Raman-detuned laser pulses to achieve spatially-varying control of the
amplitude and phase of the spinor order parameter of a Bose-Einstein
condensate. We present experimental results confirming precise radial and
azimuthal control of amplitude and phase during the creation of
vortex-antivortex superposition states.
\\ ( , 642kb)

Date: Thu, 4 Dec 2008 16:52:51 GMT (64kb)

Title: Mechanical and superfluid properties of dislocations in solid He4
Authors: D. Aleinikava, E. Dedits, A. B. Kuklov, D. Schmeltzer
Categories: cond-mat.stat-mech
Comments: 4 pages with 2 figures
   Dislocations are shown to be smooth at zero temperature because of the
effective Coulomb-type interaction between kinks. Crossover to finite
temperature rougnehing is suggested to be a mechanism responsible for the
softening of \he4 shear modulus recently observed by Day and Beamish (Nature,
{\bf 450}, 853 (2007)). We discuss also that strong suppresion of superfuidity
along the dislocation core by thermal kinks can lead to locking in of the
mechanical and superfluid responses.
\\ ( , 64kb)

Date: Thu, 4 Dec 2008 18:20:45 GMT (6kb)

Title: The macroscopic qubit delusion
Authors: Robert Alicki
Categories: quant-ph
Comments: 4 pages, no figures
   There exists a large number of experimental and theoretical results
supporting the picture of "macroscopic qubits" implemented, for instance, by
Rydberg atoms, Josephson junctions or Bose-Einstein condensates - the systems
which should rather emerge in localized semiclassical states. In this note it
is shown how, under realistic conditions, the false qubit interpretation can be
consistent with the restricted set of experimental data collected for
semiclassical systems. The recent experiments displaying semiclassical
character of Bose-Einstein condensates and possible quantumness tests for a
single system are briefly invoked also.
\\ ( , 6kb)

Date: Thu, 4 Dec 2008 18:40:20 GMT (752kb)

Title: Formation of ultracold dipolar molecules in the lowest vibrational
   levels by photoassociation
Authors: J. Deiglmayr, M. Repp, A. Grochola, K. M\"ortlbauer, C. Gl\"uck, O.
   Dulieu, J. Lange, R. Wester, and M. Weidem\"uller
Categories: physics.atom-ph
Comments: Submitted to Faraday Discussions 142: Cold and Ultracold Molecules 18
   pages, 8 figures
   We recently reported the formation of ultracold LiCs molecules in the
rovibrational ground state X1Sigma+,v''=0,J''=0 [J. Deiglmayr et al., PRL 101,
133004 (2008)]. Here we discuss details of the experimental setup and present a
thorough analysis of the photoassociation step including the photoassociation
line shape. We predict the distribution of produced ground state molecules
using accurate potential nergy curves combined with an ab-initio dipole
transition moment and compare this prediction with experimental ionization
spectra. Additionally we improve the value of the dissociation energy for the
X1Sigma+ state by high resolution spectroscopy of the vibrational ground state.
\\ ( , 752kb)

Date: Wed, 3 Dec 2008 15:35:31 GMT (9kb)

Title: On the Lieb-Liniger model in the infinite coupling constant limit
Authors: Stephane Ouvry, Alexios P. Polychronakos
Categories: cond-mat.stat-mech cond-mat.other hep-th physics.atom-ph
   We consider the one-dimensional Lieb-Liniger model (bosons interacting via
2-body delta potentials) in the infinite coupling constant limit (the so-called
Tonks-Girardeau model). This model might be relevant as a description of atomic
Bose gases confined in a one-dimensional geometry. It is known to have a
fermionic spectrum since the N-body wavefunctions have to vanish at coinciding
points, and therefore be symmetrizations of fermionic Slater wavefunctions. We
argue that in the infinite coupling constant limit the model is
indistinguishable from free fermions, i.e., all physically accessible
observables are the same as those of free fermions. Therefore, Bose-Einstein
condensate experiments at finite energy that preserve the one-dimensional
geometry cannot test any bosonic characteristic of such a model.
\\ ( , 9kb)
arXiv:0812.1019 (*cross-listing*)
Date: Thu, 4 Dec 2008 20:51:25 GMT (57kb,D)

Title: A versatile and reliably re-usable ultrahigh vacuum viewport
Authors: K. J. Weatherill, J. D. Pritchard, C. S. Adams, P. F. Griffin, U.
   Dammalapati and E. Riis
Categories: physics.ins-det physics.atom-ph
   We present a viewport for use in Ultra-high vacuum (UHV) based upon the
preflattened solder seal design presented in earlier work, Cox et al. Rev. Sci.
Inst. 74, 3185 (2003). The design features significant modifications to improve
long term performance. The windows have been leak tested to less than 10^-10
atm cm^3/s . From atom number measurements in an optical dipole trap loaded
from a vapor cell magneto-optical trap (MOT) inside a vacuum chamber
accommodating these viewports, we measure a trap lifetime of 9.5s suggesting a
pressure of around 10^-10 Torr limited by background Rubidium vapor pressure.
We also present a simplified design where the UHV seal is made directly to a
vacuum pipe
\\ ( , 57kb)

Date: Fri, 28 Nov 2008 10:18:00 GMT (6kb)

Title: Mathematics underlying the 2008 financial crisis, and a possible remedy
Authors: V. P. Maslov (1 and 2) and V. E. Nazaikinskii (2) ((1) Moscow State
   University, (2) Institute for Problems in Mechanics, RAS, Moscow)
Categories: physics.soc-ph
Comments: 8 pages, no figures
   Among the diverse factors contributing to the current financial and
economical crisis, there is a purely mathematical law not mentioned by
economists. The indistinguishability of identical notes results in a
condensation phenomenon (also known in a completely different situation in
physics as Bose condensation): if the total amount of money in circulation
exceeds a certain threshold (depending on various economic factors), then a
collapse occurs. One possible remedy is to introduce several currencies to be
used simultaneously; we show that this raises the threshold and thus might help
at least to postpone the crisis. If each of the United States were to use its
own unique currency along with the dollar, the threshold would be up to seven
times higher, and the crisis may not have happened yet. The former abandonment
of national currencies in euro countries in favor of one unique European money
could also be viewed as an unfavorable factor in the development of the crisis.
\\ ( , 6kb)

The replacements:

replaced with revised version Fri, 28 Nov 2008 17:09:47 GMT (76kb)

Title: Critical temperature of non-interacting Bose gases on disordered
Authors: L. Dell'Anna, S. Fantoni, P. Sodano, A. Trombettoni
Categories: cond-mat.stat-mech cond-mat.dis-nn
Comments: 18 pages, 8 figures; Fig. 8 improved adding results for another value
   of q (q=830/1076)
Journal-ref: J. Stat. Mech. P11012 (2008)
DOI: 10.1088/1742-5468/2008/11/P11012
\\ ( , 76kb)
replaced with revised version Thu, 27 Nov 2008 09:19:51 GMT (153kb)

Title: Functional renormalisation group approach to far-from-equilibrium
   quantum field dynamics
Authors: Thomas Gasenzer and Jan M. Pawlowski
Categories: cond-mat.other hep-ph hep-th
Comments: 6 pages, RevTeX, 5 figures, published version
Report-no: HD-THEP-07-31
Journal-ref: Phys. Lett. B 670, 135 (2008)
DOI: 10.1016/j.physletb.2008.10.049
\\ ( , 153kb)
replaced with revised version Mon, 1 Dec 2008 14:06:59 GMT (23kb)

Title: Conserving Gapless Mean-Field Theory of a Multi-Component Bose-Einstein
Authors: Yoshiyuki Kondo, Takafumi Kita
Categories: cond-mat.stat-mech
Comments: 8 pages, 7 figures Minor errors removed
Journal-ref: J. Phys. Soc. Jpn. 76, 024008 (2007)
\\ ( , 23kb)
replaced with revised version Sat, 29 Nov 2008 17:25:37 GMT (239kb,D)

Title: Simulation of an inhomogeneous Fermi gas through the BCS-BEC crossover
Authors: R. Jauregui, R. Paredes, L. Rosales-Zarate, and G. Toledo Sanchez
Categories: cond-mat.other
Comments: 15 pages,7 figures Comparison with results predicted by a recent
   virial theorem is made. New relevant references are added
\\ ( , 239kb)
replaced with revised version Mon, 1 Dec 2008 17:17:02 GMT (24kb)

Title: Adiabatic nonlinear probes of one-dimensional Bose gases
Authors: C. De Grandi, R. A. Barankov, A. Polkovnikov
Categories: cond-mat.other
Comments: 4 pages, 3 figures, final version
\\ ( , 24kb)
replaced with revised version Mon, 1 Dec 2008 14:35:49 GMT (106kb)

Title: Quantum Diffusion of Matter Waves in 2D Speckle Potentials
Authors: C. Miniatura, R.C. Kuhn, D. Delande, C.A. Mueller
Categories: cond-mat.dis-nn cond-mat.other
Comments: some structural changes and corrected fig. 2, final version
\\ ( , 106kb)
replaced with revised version Mon, 1 Dec 2008 15:04:45 GMT (96kb)

Title: Nonlinear transmission through a tapered fiber in rubidium vapor
Authors: S.M. Hendrickson, T.B. Pittman and J.D. Franson
Categories: quant-ph
Comments: 10 pages, 4 figures
\\ ( , 96kb)
replaced with revised version Sun, 30 Nov 2008 02:20:38 GMT (1926kb)

Title: Exact coherent matter-wave soliton induced and controlled by laser field
Authors: Wenhua Hai, Qiongtao Xie, Qianquan Zhu
Categories: quant-ph
Comments: 4 pages, 4figures
\\ ( , 1926kb)
replaced with revised version Tue, 2 Dec 2008 13:02:14 GMT (205kb)

Title: Particle-hole fluctuations in the BCS-BEC Crossover
Authors: S. Floerchinger, M. Scherer, S. Diehl and C. Wetterich
Categories: cond-mat.supr-con
Comments: 11 pages, 6 figures. Reference added
Journal-ref: Phys. Rev. B 78, 174528 (2008)
DOI: 10.1103/PhysRevB.78.174528
\\ ( , 205kb)
replaced with revised version Tue, 2 Dec 2008 12:50:27 GMT (46kb,D)

Title: Excess noise depletion of a Bose-Einstein condensate in an optical
Authors: G. Szirmai, D. Nagy, P. Domokos
Categories: quant-ph
Comments: 4 pages, 2 figures included in text
\\ ( , 46kb)
replaced with revised version Wed, 3 Dec 2008 10:07:55 GMT (1109kb)

Title: Unitary polarized Fermi gas under adiabatic rotation
Authors: I. Bausmerth, A. Recati, S. Stringari
Categories: cond-mat.other
Comments: 8 pages, 11 figures, discussion added according to referee report,
   final version as published
Journal-ref: Physical Review A 78, 063603 (2008)
DOI: 10.1103/PhysRevA.78.063603
\\ ( , 1109kb)
replaced with revised version Wed, 3 Dec 2008 01:01:02 GMT (51kb)

Title: Boson Hubbard model with weakly coupled Fermions
Authors: R. M. Lutchyn, S. Tewari, and S. Das Sarma
Categories: cond-mat.str-el cond-mat.supr-con quant-ph
Comments: 4 pages, 1 figure; final version as published in PRB
\\ ( , 51kb)
replaced with revised version Thu, 4 Dec 2008 16:25:09 GMT (59kb)

Title: Scheme for implementing atomic multiport devices
Authors: Jessica J. Cooper, David W. Hallwood, Jacob A. Dunningham
Categories: quant-ph
Comments: 21 pages, 7 figures
\\ ( , 59kb)

Till next time,

Dr M. J. Davis,                      Associate Professor in Physics
School of Mathematics and Physics,   ph  : +61 7 334 69824
The University of Queensland,        fax : +61 7 336 51242
Brisbane, QLD 4072,        
Matt's arXiv selection: weekly summary of cold-atom papers from
Legal stuff: Unless stated otherwise, this e-mail represents only the
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Received on Mon Jan 12 2009 - 10:24:29 EST

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