Matt's arXiv selection: week ending 6 June 2008

From: Matthew Davis <>
Date: Tue, 24 Jun 2008 20:30:16 +1000

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

Hello again,

This week had 31 new preprints and 9 replacements.

Date: Fri, 30 May 2008 07:27:28 GMT (63kb)

Title: Ground-state properties of fermionic mixtures with mass imbalance in
   optical lattices
Authors: Pavol Farkasovsky
Categories: cond-mat.str-el
Comments: 10 pages, 5 figures
   Ground-state properties of fermionic mixtures confined in a one-dimensional
optical lattice are studied numerically within the spinless Falicov-Kimball
model with a harmonic trap. A number of remarkable results are found. (i) At
low particle filling the system exhibits the phase separation with heavy atoms
in the center of the trap and light atoms in the surrounding regions. (ii)
Mott-insulating phases always coexist with metallic phases. (iii)
Atomic-density waves are observed in the insulating regions for all particle
fillings near half-filled lattice case. (iv) The variance of the local density
exhibits the universal behavior (independent of the particle filling, the
Coulomb interaction and the strength of a confining potential) over the whole
region of the local density values.
\\ ( , 63kb)
Date: Fri, 30 May 2008 14:42:42 GMT (351kb)

Title: Collective excitations in one-dimensional ultracold Fermi gases: a
   comparative study
Authors: Wei Li, Gao Xianlong, Corinna Kollath, Marco Polini
Categories: cond-mat.str-el
Comments: 11 pages, 6 figures, submitted
   Time-dependent density-functional theory (TDDFT) is a powerful tool to study
the non-equilibrium dynamics of inhomogeneous interacting many-body systems.
Here we show that the simple adiabatic local-spin-density approximation for the
time-dependent exchange-correlation potential is surprisingly accurate in
describing collective density and spin dynamics in strongly correlated
one-dimensional ultracold Fermi gases. Our conclusions are based on extensive
comparisons between our TDDFT results and accurate results based on the
adaptive time-dependent density-matrix renormalization-group method.
\\ ( , 351kb)
Date: Fri, 30 May 2008 07:08:56 GMT (156kb)

Title: Stability of Fock states in a two-component Bose-Einstein condensate
   with a regular classical counterpart
Authors: Wen-ge Wang, Jie Liu, and Baowen Li
Categories: quant-ph
Comments: 8 pages and 8 figures
   We study the stability of a two-component Bose-Einstein condensate (BEC) in
the parameter regime in which its classical counterpart has regular motion. The
stability is characterized by the fidelity for both the same and different
initial states. We study as initial states the Fock states with definite
numbers of atoms in each component of the BEC. It is found that for some
initial times the two Fock states with all the atoms in the same component of
the BEC are stabler than Fock states with atoms distributed in the two
components. An experimental scheme is discussed, in which the fidelity can be
measured in a direct way.
\\ ( , 156kb)
Date: Fri, 30 May 2008 15:37:21 GMT (112kb)

Title: Structure of quantum correlations in momentum space and off diagonal
   long range order in eta pairing and BCS states
Authors: Paolo Giorda and Alberto Anfossi
Categories: quant-ph
Comments: 11 pages, 3 figures
   The quantum states built with the eta paring mechanism i.e., eta pairing
states, were first introduced in the context of high temperature
superconductivity where they were recognized as important example of states
allowing for off-diagonal long-range order (ODLRO). In this paper we describe
the structure of the correlations present in these states when considered in
their momentum representation and we explore the relations between the quantum
bipartite/multipartite correlations exhibited in k space and the direct lattice
superconducting correlations. In particular, we show how the negativity between
paired momentum modes is directly related to the ODLRO. Moreover, we
investigate the dependence of the block entanglement on the choice of the modes
forming the block and on the ODLRO; consequently we determine the multipartite
content of the entanglement through the evaluation of the generalized "Meyer
Wallach" measure in the direct and reciprocal lattice. The determination of the
persistency of entanglement shows how the network of correlations depicted
exhibits a self-similar structure which is robust with respect to "local"
measurements. Finally, we recognize how a relation between the momentum-space
quantum correlations and the ODLRO can be established even in the case of BCS
\\ ( , 112kb)

Date: Fri, 30 May 2008 22:17:23 GMT (163kb)

Title: Ground state of low dimensional dipolar gases: linear, zigzag and
   multiple chains
Authors: G. E. Astrakharchik, Giovanna Morigi, Gabriele De Chiara, and J.
Categories: cond-mat.other
   We study the ground state properties of ultracold dipolar gases in highly
anisotropic traps. Starting from a one-dimensional geometry, by ramping down
the transverse confinement along one direction, the gas reaches various planar
distributions of dipoles. At large linear densities, when the dipolar gas
exhibits a crystal-like phase, one can identify critical values of the
transverse frequency at which the configuration starts exhibiting novel
transverse spatial correlations. These critical values can be identified by
means of a classical theory, and are in full agreement with classical Monte
Carlo simulations. The numerical study of the quantum system is performed by
using diffusion Monte Carlo technique and shows that the quantum fluctuations
smoothen the transition and make it completely disappear in a gas phase.
\\ ( , 163kb)
Date: Mon, 2 Jun 2008 19:15:45 GMT (642kb,D)

Title: Preparation and detection of d-wave superfluidity in two-dimensional
   optical superlattices
Authors: A. M. Rey, R. Sensarma, S. Foelling, M. Greiner, E. Demler and M.D.
Categories: cond-mat.other
Comments: 8 pages, 6 figures
   We propose a controlled method to create and detect d-wave superfluidity with
ultracold fermionic atoms loaded in two-dimensional optical superlattices. Our
scheme consists in preparing an array of nearest-neighbor coupled square
plaquettes or ``superplaquettes'' and using them as building blocks to
construct a d-wave superfluid state. We describe how to use the coherent
dynamical evolution in such a system to experimentally probe the pairing
mechanism. We also derive the zero temperature phase diagram of the fermions in
a checkerboard lattice (many weakly coupled plaquettes) and show that by tuning
the inter-plaquette tunneling spin-dependently or varying the filling factor
one can drive the system into a d-wave superfluid phase or a Cooper pair
density wave phase. We discuss the use of noise correlation measurements to
experimentally probe these phases.
\\ ( , 642kb)

Date: Mon, 2 Jun 2008 08:04:30 GMT (18kb)

Title: Luttinger liquid coupled to Bose-Einstein condensation reservoirs
Authors: Fang Cheng, Guobao Zhu, W. M. Liu, Guanghui Zhou
Categories: cond-mat.str-el cond-mat.dis-nn
   We investigate the transport properties for a Luttinger liquid coupled to two
identical Bose-Einstein condensation reservoirs. Using the approach of equation
of motion for the Green function of the system, we find that the distance
between the two resonant transmission probability peaks of the system is
determined by the bosonic interaction strengths, and the sharpness of these
resonant peaks is mainly determined by the Rabi frequency and phase of the
Bose-Einstein condensation reservoir. These results for the proposed system
involving a Luttinger liquid may build a bridge between the controling
transport properties of cold atom in atom physics and the interacting boson
transport in low-dimensional condensed matter physics.
\\ ( , 18kb)
Date: Mon, 2 Jun 2008 10:11:39 GMT (433kb,D)

Title: Decay of multiply charged vortices at nonzero temperatures
Authors: Tomasz Karpiuk, Miroslaw Brewczyk, Mariusz Gajda, Kazimierz Rzazewski
Categories: cond-mat.other
Comments: 4 pages, 6 figures
   We study the instability of multiply charged vortices in the presence of
thermal atoms and find various scenarios of splitting of such vortices. The
onset of the decay of a vortex is always preceded by the increase of a number
of thermal (uncondensed) atoms in the system and manifests itself by the sudden
rise of the amplitude of the oscillations of the quadrupole moment. Our
calculations show that the decay time gets shorter when the multiplicity of a
vortex becomes higher.
\\ ( , 433kb)
Date: Mon, 2 Jun 2008 12:13:46 GMT (83kb)

Title: Effects of Axial Vorticity in Elongated Mixtures of Bose-Einstein
Authors: L. Salasnich, B.A. Malomed and F. Toigo
Categories: cond-mat.other cond-mat.stat-mech
Comments: 4 pages, 3 figures
Journal-ref: Phys. Rev. A 77, 035601 (2008)
DOI: 10.1103/PhysRevA.77.035601
   We consider a meniscus between rotating and nonrotating species in the
Bose-Einstein condensate (BEC) with repulsive inter-atomic interactions,
confined to a pipe-shaped trap. In this setting, we derive a system of coupled
one-dimensional (1D) nonpolynomial Schrodinger equations (NPSEs) for two
mean-field wave functions. Using these equations, we analyze the phase
separation/mixing in the pipe with periodic axial boundary conditions, i.e. in
a toroidal configuration. We find that the onset of the mixing, in the form of
suction, i.e., filling the empty core in the vortical component by its
nonrotating counterpart, crucially depends on the vorticity of the first
component, and on the strengths of the inter-atomic interactions.
\\ ( , 83kb)

Date: Mon, 2 Jun 2008 06:09:47 GMT (600kb,D)

Title: Paired atom laser beams created via four-wave mixing
Authors: R. G. Dall, L. J. Byron, A. G. Truscott, G. R. Dennis, M. T. Johnsson,
   J. J. Hope
Categories: quant-ph
Comments: 5 pages, 3 figures
   A simple method to create paired atom laser beams from a metastable helium
atom laser via four-wave mixing is demonstrated. Radio frequency outcoupling is
used to outcouple atoms from a Bose Einstein condensate near the center of the
condensate and initiate scattering between trapped and untrapped atoms. The
unequal strengths of the interactions for different internal states allows an
energy resonance for the creation of pairs of atoms scattered from the
zero-velocity condensate. The resulting scattered beams are well separated from
the main atom laser in the 2-dimensional transverse atom laser profile.
Numerical simulations of the system are in good agreement with the observed
atom laser spatial profiles, and verify that the scattered beams are generated
by a four-wave mixing process, suggesting that the beams are correlated.
\\ ( , 600kb)
Date: Sat, 31 May 2008 11:22:27 GMT (1189kb)

Title: The Einstein-Podolsky-Rosen paradox - a fundamental challenge and a tool
   for quantum engineering
Authors: M. D. Reid, P. D. Drummond, E. G. Cavalcanti, W. P. Bowen, P. K. Lam,
   H. A. Bachor, U. L. Andersen, G. Leuchs
Categories: quant-ph
Comments: Colloquium submitted to Reviews of Modern Physics
   This Colloquium examines the\textbf{\emph{}}field of the EPR paradox, from
the original paper of Einstein, Podolsky and Rosen, through to modern
theoretical proposals of how to realize both the continuous-variable and
discrete versions of the EPR paradox. We analyze the relationship with
entanglement and Bell's theorem, and summarize the progress to date towards
experimental confirmation of the EPR paradox, with a detailed treatment of the
continuous-variable paradox in laser-based experiments. Practical techniques
covered include continuous-wave parametric amplifier and optical fibre quantum
soliton experiments. We discuss current proposals for extending EPR experiments
to massive-particle systems, including spin-squeezing, atomic position
entanglement, and quadrature entanglement in ultra-cold atoms. Finally, we
examine applications of this technology to quantum key distribution, quantum
teleportation and entanglement-swapping.
\\ ( , 1189kb)
Date: Sun, 1 Jun 2008 19:03:15 GMT (404kb)

Title: Operating an atom interferometer beyond its linear range
Authors: S\'ebastien Merlet (SYRTE), J. Le Gou\"et (SYRTE), Quentin Bodart
   (SYRTE), Andre Clairon (SYRTE, BNM-SYRTE), Arnaud Landragin (SYRTE), Franck
   Pereira Dos Santos (SYRTE), Pierre Rouchon (CAS, ENSMP)
Categories: physics.atom-ph
Comments: 20 pages, 8 figures
   In this paper, we show that an atom interferometer inertial sensor, when
associated to the auxiliary measurement of external vibrations, can be operated
beyond its linear range and still keep a high acceleration sensitivity. We
propose and compare two measurement procedures (fringe fitting and nonlinear
lock) that can be used to extract the mean phase of the interferometer when the
interferometer phase fluctuations exceed $2\pi$. Despite operating in the urban
environment of inner Paris without any vibration isolation, the use of a low
noise seismometer for the measurement of ground vibrations allows our atom
gravimeter to reach at night a sensitivity as good as $5.5\times10^{-8}$g at 1
s. Robustness of the measurement to large vibration noise is also demonstrated
by the ability of our gravimeter to operate during an earthquake with excellent
sensitivity. Our high repetition rate allows for recovering the true low
frequency seismic vibrations, ensuring proper averaging. Such techniques open
new perspectives for applications in other fields, such as navigation and
\\ ( , 404kb)
Date: Mon, 2 Jun 2008 20:02:26 GMT (155kb)

Title: Topological Zero modes in fermionic condensate phases on the honeycomb
Authors: Doron L. Bergman and Karyn Le Hur
Categories: cond-mat.supr-con
   We investigate a number of fermionic condensate phases on the honeycomb
lattice, to determine whether topological defects (vortices and edges) in these
phases can support bound states with zero energy. We argue that zero modes
bound to vortices and at edges are not only connected, but should in fact be
\emph{identified}. Recently, it has been shown that the simplest s-wave
superconducting state for the Dirac fermion approximation of the honeycomb
lattice at precisely half filling, supports (near) zero modes inside the cores
of vortices (P. Ghaemi and F. Wilczek, 2007). We find that the zero modes are
not unique neither to this phase, nor to half filling. In addition, we find
that the \emph{exact} wavefunctions for vortex bound zero modes, as well as the
complete edge state spectrum of the phases we discuss. The zero modes in all
the phases we examine have even-numbered degeneracy, and as such pairs of any
Majorana modes are simply equivalent to one ordinary fermion. As a result,
contrary to bound state zero modes in $p_x+i p_y$ superconductors, vortices
here do \emph{not} exhibit non-Abelian exchange statistics. Finally, we make a
number of suggestions to determine experimentally the existence of these unique
bound states in graphene or cold atom fermionic condensates.
\\ ( , 155kb)
Date: Tue, 3 Jun 2008 01:35:29 GMT (104kb)

Title: Odd-frequency pairing in binary boson-fermion cold atom mixtures
Authors: Ryan M. Kalas, Alexander V. Balatsky, Dmitry Mozyrsky
Categories: cond-mat.other
Comments: 4 pages, 1 figure
   We study fermionic superfluidity in a boson-single-species-fermion cold atom
mixture. We argue that apart from the standard p-wave fermion pairing mediated
by the phonon field of the boson gas, the system also exhibits s-wave pairing
with the anomalous correlator being an odd function of time or frequency. We
show that such a superfluid phase, while typically having a much higher
transition temperature than the p-wave, may only exist for sufficiently strong
couplings between fermions and bosons. These conditions for odd-frequency
pairing are favorable close to the value of the coupling at which the mixture
phase-separates. We evaluate the finite-temperature phase diagram for this
system and discuss the experimental realization and signatures of this novel
superfluid in ultracold atomic gases.
\\ ( , 104kb)
Date: Tue, 3 Jun 2008 02:39:37 GMT (114kb)

Title: Universality and Anomalous Mean-Field Breakdown of Symmetry-Breaking
   Transitions in A Coupled Two-Component Condensate
Authors: Chaohong Lee
Categories: cond-mat.mes-hall cond-mat.other
Comments: 4 pages, 3 eps figures
   We study both mean-field and full quantum dynamics of symmetry-breaking
transitions in a coupled two-component Bose-Einstein condensate. By controlling
s-wave scattering lengths and coupling strength, it is possible to stimulate
symmetry-breaking transitions between normal and spontaneously polarized ground
states. In static transitions, the probability maxima of full quantum ground
states correspond to the mean-field ground states. In dynamical transitions,
due to the appearance of gapless Bogoliubov excitations, the mean-field
dynamics obeys universal Kibble-Zurek-like scalings. Both mean-field and full
quantum defect modes appear as damped oscillations, but they appear at
different critical points and undergo different oscillation regimes. The
anomalous breakdown of mean-field dynamics induced by symmetry-breaking
transitions depends on the transition direction.
\\ ( , 114kb)
Date: Tue, 3 Jun 2008 08:10:51 GMT (437kb)

Title: Creating a supersolid in one-dimensional Bose mixtures
Authors: L. Mathey, Ippei Danshita, and Charles W. Clark
Categories: cond-mat.other
Comments: 4 pages, 5 figures
   We identify a one-dimensional supersolid phase in a binary mixture of
near-hardcore bosons with weak, local inter-species repulsion. We find
realistic conditions under which such a phase, defined here as the coexistence
of quasi-superfluidity and quasi-charge density wave order, can be produced and
observed in finite ultra-cold atom systems in a harmonic trap. Our analysis is
based on Luttinger liquid theory supported with numerical calculations using
the time-evolving block decimation method. Clear experimental signatures of
these two orders can be found, respectively, in time-of-flight interference
patterns, and the structure factor S(k) derived from density correlations.
\\ ( , 437kb)
Date: Tue, 3 Jun 2008 08:44:53 GMT (794kb)

Title: Correlation Effects on Atom Density Profiles of 1-D and 2-D Polarized
   Atomic-Fermi-Gas Loaded on Optical Lattice
Authors: M. Machida, S. Yamada, M. Okumura, Y. Ohashi, H. Matsumoto
Categories: cond-mat.str-el
Comments: A reference is added to the published version
Journal-ref: Phys. Rev. A 77, 053614 (2008)
DOI: 10.1103/PhysRevA.77.053614
   We investigate effects of optical lattice potential in one- and
two-dimensional two-component trapped Fermi gases with population imbalances.
Using the exact diagonalization and the density matrix renormalization group
methods complementarily, we calculate the atom density profile from the ground
state many-body wavefunction as a function of attractive interaction strength
for various population imbalances. The numerical results reveal that although a
phase separation between the superfluid core and the shell cloud of excess
atoms occurs as observed in experiments without the optical lattice, the
population imbalance generally remains in the core region in contrast to the
non-lattice cases. The essence of the numerical results in a strong attractive
regime can be explained by an effective model composed of Cooper pairs and
excess major fermions.
\\ ( , 794kb)

Date: Tue, 3 Jun 2008 09:27:45 GMT (21kb)

Title: Supercurrent behavior of low-energy Bogoliubov phonon and anomalous
   tunneling effect in a Bose-Einstein condensate
Authors: Yoji Ohashi, and Shunji Tsuchiya
Categories: cond-mat.other
Comments: 22 pages, 3 figures
   We investigate tunneling properties of Bogoliubov mode in a Bose-Einstein
condensate. Using an exactly solvable model with a delta-functional barrier, we
show that each component in the two-component wavefunction (u,v) of low-energy
Bogoliubov phonon has the same form as the condensate wavefunction in the
supercurrent state. As a result, the currents J_u and J_v associated with u and
v, respectively, have the same tunneling properties as those of supercurrent
carried by condensate. Thus, the tunneling of low-energy Bogoliubov phonon
described by the tunneling of these two currents shows perfect transmission. We
also show that the supercurrent behaviors of Bogoliubov phonon still exist in
the presence of supercurrent carried by condensate, except in the critical
supercurrent state. In the critical current state, the perfect transmission is
absent, because J_u or J_v exceeds their upper limit given by the critical
value of the supercurrent associated with the condensate. Our results
consistently explain the recently proposed two tunneling phenomena associated
with Bogoliubov phonon, namely, the anomalous tunneling effect (perfect
transmission in the low-energy limit) and the breakdown of the perfect
transmission in the critical supercurrent state.
\\ ( , 21kb)
Date: Tue, 3 Jun 2008 17:02:38 GMT (149kb,D)

Title: Collisional stability of a three-component degenerate Fermi gas
Authors: T. B. Ottenstein, T. Lompe, M. Kohnen, A. N. Wenz and S. Jochim
Categories: cond-mat.other
   We report on the creation of a degenerate Fermi gas consisting of a balanced
mixture of atoms in three different hyperfine states of $^6$Li. This new system
consists of three distinguishable Fermions with different and tunable
interparticle scattering lengths $a_{12}$, $a_{13}$ and $a_{23}$. We are able
to prepare samples containing $5 \cdot 10^4$ atoms in each state at a
temperature of about $215 $nK, which corresponds to $T/T_F \approx 0.37$. We
investigated the collisional stability of the gas for magnetic fields between 0
and 600 G and found a prominent loss feature at 130 G. From lifetime
measurements we determined three-body loss coefficients, which we found to vary
over nearly three orders of magnitude.
\\ ( , 149kb)
Date: Tue, 3 Jun 2008 17:21:02 GMT (117kb)

Title: Fermion mediated interactions in a dilute Bose-Einstein condensate
Authors: D. H. Santamore, Eddy Timmermans
Categories: cond-mat.stat-mech
Comments: 16 pages, 6 figures
   We develop a diagrammatic perturbation treatment to calculate the
zero-temperature equation of state of the dilute gas mixture of a single spin
component Bose-Einstein condensate (BEC) and a normal Fermi-gas of
indistinguishable (single spin) fermion particles. We find that the mean-field
description breaks down near the mechanical instability related to the phase
separation phenomenon. Our analysis shows that the instability is caused by the
competition of the usual short-range and fermion-mediated boson-boson
interactions, which result in a boson compressibility that diverges. In the low
BEC-density limit, we show that the diagrammatic analysis simplifies, we sum
part of the higher order diagrams and we discuss the effects of other higher
order contributions.
\\ ( , 117kb)
Date: Tue, 3 Jun 2008 07:53:31 GMT (159kb)

Title: Criteria for generalized macroscopic and mesoscopic quantum coherence
Authors: E. G. Cavalcanti and M. D. Reid
Categories: quant-ph
Comments: 15 pages, accepted for publication in Phys. Rev. A
   We consider macroscopic, mesoscopic and "S-scopic" quantum superpositions of
eigenstates of an observable, and develop some signatures for their existence.
We define the extent, or size $S$ of a superposition, with respect to an
observable \hat{x}, as being the range of outcomes of \hat{x} predicted by that
superposition. Such superpositions are referred to as generalized $S$-scopic
superpositions to distinguish them from the extreme superpositions that
superpose only the two states that have a difference $S$ in their prediction
for the observable. We also consider generalized $S$-scopic superpositions of
coherent states. We explore the constraints that are placed on the statistics
if we suppose a system to be described by mixtures of superpositions that are
restricted in size. In this way we arrive at experimental criteria that are
sufficient to deduce the existence of a generalized $S$-scopic superposition.
The signatures developed are useful where one is able to demonstrate a degree
of squeezing. We also discuss how the signatures enable a new type of
Einstein-Podolsky-Rosen gedanken experiment.
\\ ( , 159kb)
Date: Tue, 3 Jun 2008 20:00:14 GMT (8kb)

Title: Microscopic justification of the Kelvin's statement on thermodynamics
Authors: Anatoli Polkovnikov
Categories: cond-mat.stat-mech
Comments: 5 pages, no figures
   We prove the theorem that in a cyclic process over a Hamiltonian system the
energy of the system can either increase or stay the same provided that (i) the
initial density matrix of the system is stationary (i.e. diagonal in the energy
eigenbasis) and (ii) the initial occupancy of different many body levels given
by diagonal elements of the density matrix is a monotonically decreasing
function of energy, i.e. $\rho_{n}\leq \rho_{m}$ if $E_n\geq E_m$. This
theorem, in particular implies, that it is impossible to extract work from an
isolated system satisfying the initial constraints by reducing its energy,
which in turn is equivalent to the Kelvin's formulation of the second law of
thermodynamics and which can be used to prove impossibility of the {\em
perpetuum mobile} of the second type.
\\ ( , 8kb)
Date: Wed, 4 Jun 2008 14:33:21 GMT (30kb)

Title: Long Cycles in the Infinite-Range-Hopping Bose-Hubbard Model with Hard
Authors: G. Boland, J.V. Pul\'e
Categories: cond-mat.stat-mech
Comments: 26 pages, 2 figures. To appear in JSP
   In this paper we study the relation between long cycles and Bose-Condensation
in the Infinite range Bose-Hubbard Model with a hard core interaction. We
calculate the density of particles on long cycles in the thermodynamic limit
and find that the existence of a non-zero long cycle density coincides with the
occurrence of Bose-Einstein condensation but this density is not equal to that
of the Bose condensate.
\\ ( , 30kb)
Date: Wed, 4 Jun 2008 17:27:43 GMT (253kb)

Title: Vortex Formation by an off-axis oscillating spherical quadrupole field
   in a Bose-Einstein condensate
Authors: E. A. L. Henn, J. A. Seman, E. R. F. Ramos, M. Caracanhas, P.
   Castilho, E. P. Olimpio, G. Roati, D. V. Magalh\~aes, K. M. F. Magalh\~aes,
   V.S. Bagnato
Categories: cond-mat.other cond-mat.mes-hall
Comments: 4 pages, 5 figures
   We present a new technique to generate vortices in gaseous Bose-Einstein
condensates. The method consists in superimpose an oscillating spherical
quadupole magnetic field to the QUIC magnetic trap where we have produced a
sample of 1-2$\times10^5$ Bose condensed $^{87}$Rb atoms. The external field
symmetry axis is not parallel to the trap axis nor its center coincides with
the trapping field minimum position. For small amplitudes of the external
excitation field we observe a tilt of the cloud axis. Increasing the amplitude
we observe formation of an increasing number of vortices in the sample.
Shot-to-shot variations in both vortex number and position within the condensed
cloud are observed, probably due to the intrinsic vortex nucleation dynamics.
We discuss the possible formation of vortices and anti-vortices in the sample.
\\ ( , 253kb)
Date: Wed, 4 Jun 2008 17:23:58 GMT (96kb)

Title: Formation of deeply bound molecules via chainwise adiabatic passage
Authors: Elena Kuznetsova, Philippe Pellegrini, Robin C\^ot\'e, M.D. Lukin,
   S.F. Yelin
Categories: quant-ph
   We suggest and analyze a novel technique for efficient and robust creation of
dense ultracold molecular ensembles in their ground rovibrational state. In our
approach a molecule is brought to the ground state through a series of
intermediate vibrational states via a {\em multistate chainwise Stimulated
Raman Adiabatic Passage} (c-STIRAP) technique. We study the influence of the
intermediate states decay on the transfer process and suggest an approach that
minimizes the population of these states, resulting in a maximal transfer
efficiency. As an example, we analyze the formation of $^{87}$Rb$_{2}$ starting
from an initial Feshbach molecular state and taking into account major decay
mechanisms due to inelastic atom-molecule and molecule-molecule collisions.
Numerical analysis suggests a transfer efficiency $>$ 90%, even in the presence
of strong collisional relaxation as are present in a high density atomic gas.
\\ ( , 96kb)
Date: Tue, 3 Jun 2008 23:47:02 GMT (605kb)

Title: Controlling atomic vapor density in paraffin-coated cells using
   light-induced atomic desorption
Authors: T. Karaulanov, M. T. Graf, D. English, S. M. Rochester, Y. Rosen, K.
   Tsigutkin, D. Budker, E. B. Alexandrov, M. V. Balabas, D. F. Jackson Kimball,
   F. A. Narducci, S. Pustelny, V. V. Yashchuk
Categories: physics.atom-ph
Comments: 9 pages, 9 figures
   Atomic-vapor density change due to light induced atomic desorption (LIAD) is
studied in paraffin-coated rubidium, cesium, sodium and potassium cells. In the
present experiment, low-intensity probe light is used to obtain an absorption
spectrum and measure the vapor density, while light from an argon-ion laser or
discharge lamp is used for desorption. Potassium is found to exhibit
significantly weaker LIAD from paraffin compared to Rb and Cs, and we were
unable to observe LIAD with sodium. A simple LIAD model is applied to describe
the observed vapor-density dynamics, and the role of the cell's stem is
explored through the use of cells with lockable stems. The results of this work
could be used to assess the use of LIAD for vapor-density control in
magnetometers, clocks, and gyroscopes utilizing coated cells.
\\ ( , 605kb)
Date: Thu, 5 Jun 2008 13:52:07 GMT (1098kb)

Title: Excitations of attractive 1-D bosons: Binding vs. fermionization
Authors: Emmerich Tempfli, Sascha Z\"ollner, Peter Schmelcher
Categories: cond-mat.other
Comments: 7 pages, 5 figures
   The stationary states of few bosons in a one-dimensional harmonic trap are
investigated throughout the crossover from weak to strongly attractive
interactions. For sufficient attraction, three different classes of states
emerge: (i) N-body bound states, (ii) bound states of smaller fragments, and
(iii) gas-like states that fermionize, that is, map to ideal fermions in the
limit of infinite attraction. The two-body correlations and momentum spectra
characteristic of the three classes are discussed, and the results are
illustrated using the soluble two-particle model.
\\ ( , 1098kb)
arXiv:0804.2678 (*cross-listing*)
Date: Thu, 17 Apr 2008 03:37:27 GMT (93kb)
Date (revised v2): Wed, 4 Jun 2008 17:50:18 GMT (93kb)

Title: Density Functional Theory for non-relativistic Fermions in the Unitarity
Authors: Gautam Rupak and Thomas Schaefer (North Carolina State University)
Categories: nucl-th cond-mat.other
Comments: 16 pages, improved matching procedure (leads to a very small
   correction in the final result)
   We derive an energy density functional for non-relativistic spin one-half
fermions in the limit of a divergent two-body scattering length. Using an
epsilon expansion around d=4-epsilon spatial dimensions we compute the
coefficient of the leading correction beyond the local density approximation
(LDA). In the case of N fermionic atoms trapped in a harmonic potential this
correction has the form E=E_(LDA)(1+c_s (3N)^(-2/3)), where E_(LDA) is the
total energy in LDA approximation. At next-to-leading order in the epsilon
expansion we find c_s=2.41, which is significantly larger than the result for
non-interacting fermions, c_s=0.5.
\\ ( , 93kb)
Date: Thu, 5 Jun 2008 13:46:44 GMT (207kb)

Title: A compact dual atom interferometer gyroscope based on laser-cooled
Authors: T. M\"uller, M. Gilowski, M. Zaiser, T. Wendrich, W. Ertmer, and E. M.
Categories: physics.atom-ph
Comments: 9 pages, 8 figures
   We present a compact and transportable inertial sensor for precision sensing
of rotations and accelerations. The sensor consists of a dual Mach-Zehnder-type
atom interferometer operated with laser-cooled $^{87}$Rb. Raman processes are
employed to coherently manipulate the matter waves. We describe and
characterize the experimental apparatus. A method for passing from a compact
geometry to an extended interferometer with three independent atom-light
interaction zones is proposed and investigated. The extended geometry will
enhance the sensitivity by more than two orders of magnitude which is necessary
to achieve sensitivities better than $10^{-8} $rad/s/$\sqrt{\rm Hz}$.
\\ ( , 207kb)
Date: Fri, 30 May 2008 01:18:52 GMT (49kb)

Title: The w-index: A significant improvement of the h-index
Authors: Qiang Wu
Categories: physics.soc-ph
Comments: 7 pages, 3 tables
   I propose a new measure, the w-index, as a particularly simple and useful way
to assess the integrated impact of a researcher's work, especially his or her
excellent papers. The w-index can be defined as follow: A researcher has index
w if w of his/her papers have at least 10w citations each, and the other papers
have fewer than 10(w+1) citations.
\\ ( , 49kb)
Date: Thu, 5 Jun 2008 13:55:51 GMT (33kb)

Title: Universality of citation distributions: towards an objective measure of
   scientific impact
Authors: Filippo Radicchi, Santo Fortunato, Claudio Castellano
Categories: physics.soc-ph
Comments: 14 pages, 5 figures
   We study the distributions of citations received by a single publication
within several disciplines, spanning all fields of science. We show that the
probability that a paper is cited $c$ times has large variations between
different disciplines, but all distributions are rescaled on a universal curve
when the relative indicator $c/c_0$ is considered, where $c_0$ is the average
number of citations per paper for the discipline. In addition we show that the
same universal behavior occurs when citation distributions of papers published
in the same field, but in different years, are compared. These findings provide
a strong validation of $c/c_0$ as an unbiased indicator for citation
performance across disciplines and years. Based on this indicator, we introduce
a generalization of the h-index suitable for comparing scientists working in
different fields.
\\ ( , 33kb)

The replacements:

replaced with revised version Fri, 30 May 2008 12:20:27 GMT (490kb)

Title: Quasiparticles, coherence and nonlinearity: exact simulations of
   RF-spectroscopy of strongly interacting one-dimensional Fermi gases
Authors: M. J. Leskinen, V. Apaja, J. Kajala, P. Torma
Categories: cond-mat.supr-con cond-mat.other
Comments: 4 pages, 3 figures, revised version
\\ ( , 490kb)
replaced with revised version Mon, 2 Jun 2008 09:37:22 GMT (12kb)

Title: Resonant Scattering of Ultracold Atoms in Low Dimensions
Authors: Ludovic Pricoupenko (LPTMC)
Categories: cond-mat.other
Journal-ref: Physical Review Letters 100 (2008) 170404
DOI: 10.1103/PhysRevLett.100.170404
\\ ( , 12kb)
replaced with revised version Mon, 2 Jun 2008 08:37:42 GMT (378kb)

Title: Spontaneous rotating vortex lattices in a pumped decaying condensate
Authors: Jonathan Keeling, Natalia G. Berloff
Categories: cond-mat.other
Comments: Updated title and introduction. 4 pages, 3 figures
\\ ( , 378kb)
replaced with revised version Sun, 1 Jun 2008 00:13:19 GMT (177kb)

Title: Exact exponents of edge singularities in dynamic correlation functions
   of 1D Bose gas
Authors: Adilet Imambekov and Leonid I. Glazman
Categories: cond-mat.str-el
Comments: final published version
Journal-ref: Phys. Rev. Lett. 100, 206805 (2008)
DOI: 10.1103/PhysRevLett.100.206805
\\ ( , 177kb)
arXiv:0802.3164 (*cross-listing*)
replaced with revised version Sat, 31 May 2008 11:34:58 GMT (226kb)

Title: A non-Hermitian $PT-$symmetric Bose-Hubbard model: eigenvalue rings from
   unfolding higher-order exceptional points
Authors: E. M. Graefe, U. Guenther, H. J. Korsch, A. E. Niederle
Categories: math-ph cond-mat.other math.MP quant-ph
Comments: minor changes
Journal-ref: J. Phys. A: Math. Theor. 41 (2008) 255206
DOI: 10.1088/1751-8113/41/25/255206
\\ ( , 226kb)
replaced with revised version Tue, 3 Jun 2008 08:00:52 GMT (214kb,D)

Title: Spreading of correlations and entanglement after a quench in the
   one-dimensional Bose-Hubbard model
Authors: Andreas Laeuchli, Corinna Kollath
Categories: cond-mat.other
Comments: 19 pages, 9 figures
Journal-ref: J. Stat. Mech. (2008) P05018
DOI: 10.1088/1742-5468/2008/05/P05018
\\ ( , 214kb)
replaced with revised version Mon, 2 Jun 2008 20:40:34 GMT (44kb)

Title: Equation of State and Phases of Polarized Unitary Fermi Gas
Authors: S. Y. Chang
Categories: physics.atom-ph physics.atm-clus
Comments: 4 pages,4 figures
Journal-ref: Phys. Rev. A 77, 051602 (R), 2008
\\ ( , 44kb)
replaced with revised version Tue, 3 Jun 2008 11:19:35 GMT (2kb)

Title: Comment on "Multibeam atom laser: Coherent atom beam splitting from a
   single far-detuned laser"
Authors: V. A. Kuz'menko
Categories: physics.optics
Comments: 2 pages, new experimental results are discussed
\\ ( , 2kb)
replaced with revised version Thu, 5 Jun 2008 05:38:04 GMT (794kb)

Title: Correlation Effects on Atom Density Profiles of 1-D and 2-D Polarized
   Atomic-Fermi-Gas Loaded on Optical Lattice
Authors: M. Machida, S. Yamada, M. Okumura, Y. Ohashi, H. Matsumoto
Categories: cond-mat.str-el
Comments: References are added to the published version
Journal-ref: Phys. Rev. A 77, 053614 (2008)
DOI: 10.1103/PhysRevA.77.053614
\\ ( , 794kb)

Till next time,

Dr M. J. Davis,               Senior Lecturer in Physics
School of Physical Sciences,  email:
University of Queensland,     ph   : +61 7 334 69824
Brisbane, QLD 4072,           fax  : +61 7 336 51242
Matt's arXiv selection: weekly summary of cold-atom papers from
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 Wed Jun 25 2008 - 11:27:48 EST

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