RESEND: Matt's arXiv selection: week ending 30 November 2007.

From: Matthew Davis <>
Date: Thu, 20 Dec 2007 13:19:09 +1000

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

Hi all,

I'm not quite sure what happened, but for some reason my posting earlier today
was severely truncated. Here is the full list of 39 new preprints and 16

Please accept my apologies. Thanks to those who pointed it out to me!

Date: Thu, 22 Nov 2007 10:08:24 GMT (31kb)

Title: Bose-Einstein condensation in a decorated lattice: an application to
Authors: D. V. Fil, S. I. Shevchenko
Categories: cond-mat.stat-mech
Comments: 7 pages
   The Bose-Einstein condensation of vacancies in a three-dimensional decorated
lattice is considered. The model describes possible scenario of superfluidity
of solid helium, caused by the presence of zero-point vacancies in a
dislocation network. It is shown that the temperature of Bose-Einstein
condensation decreases under increase of the length of the segments of the
network, and the law of decrease depends essentially on the properties of the
vertexes of the network. If the vertexes correspond to barriers with a small
transparency, the critical temperature is inversely as the square of the length
of the segment. On the contrary, if the vertexes correspond to traps for the
vacancies (it is energetically preferable for the vacancies to localize at the
vertexes), an exponential lowering of the temperature of transition takes
place. The highest temperature of Bose-Einstein condensation is reached in the
intermediate case of vertexes with large transparency, but in the absence of
tendency of localization in them. In the latter case the critical temperature
is inversely as the length of the segment.
\\ ( , 31kb)
Date: Thu, 22 Nov 2007 17:41:17 GMT (96kb)

Title: Collective Excitations of Trapped Imbalanced Fermion Gases
Authors: Achilleas Lazarides and Bert Van Schaeybroeck
Categories: cond-mat.other cond-mat.stat-mech
Comments: 4 pages
   We present a theoretical study of the collective excitations of a trapped
imbalanced fermion gas at ultralow temperatures, when the system consists of a
superfluid core and a normal outer shell. We formulate the relevant boundary
conditions, taking into account the permeability of the interface to particles.
In the strongly interacting regime, and using a hydrodynamic approach, we
calculate the mode frequencies for spherical and highly elongated ellipsoidal
traps as a function of trap polarization. We find two distinct classes of
modes: In-phase oscillations of the superfluid and normal components, similar
to the collective modes of a single-component system, and oscillations
involving out-of-phase motion of the superfluid core and the normal shell. The
latter have frequencies below the trapping frequency.
\\ ( , 96kb)
Date: Thu, 22 Nov 2007 21:17:35 GMT (36kb)

Title: Dual Fermion Approach to Susceptibility of Correlated Lattice Fermions
Authors: S. Brener, H. Hafermann, A. N. Rubtsov, M. I. Katsnelson and A. I.
Categories: cond-mat.str-el
   We show how the two-particle Green function (2PGF) can be obtained within the
framework of the Dual Fermion approach. This facilitates the calculation of the
susceptibility in strongly correlated systems where long-ranged non-local
correlations cannot be neglected. We formulate the Bethe-Salpeter equations for
the full vertex in the particle-particle and particle-hole channels and
introduce an approximation for practical calculations. The scheme is applied to
the two-dimensional Hubbard model at half filling. The spin-spin susceptibility
is found to strongly increase for the wavevector $\mathbf{q}=(\pi,\pi)$,
indicating the antiferromagnetic instability.
\\ ( , 36kb)
Date: Fri, 23 Nov 2007 08:09:17 GMT (404kb)

Title: Entanglement growth and simulation efficiency in one-dimensional quantum
   lattice systems
Authors: Alvaro Perales and Guifre Vidal
Categories: cond-mat.str-el
Comments: 4 pages, 4 figures
   We study the evolution of one-dimensional quantum lattice systems when the
ground state is perturbed by altering one site in the middle of the chain. For
a large class of models, we observe a similar pattern of entanglement growth
during the evolution, characterized by a moderate increase of significant
Schmidt coefficients in all relevant bipartite decompositions of the state. As
a result, the evolution can be accurately described by a matrix product state
and efficiently simulated using the time-evolving block decimation algorithm.
\\ ( , 404kb)
Date: Fri, 23 Nov 2007 10:48:54 GMT (456kb)

Title: Trapped Fermi Gases in Rotating Optical Lattices: Realization and
   Detection of the Topological Hofstadter Insulator
Authors: R. O. Umucalilar, Hui Zhai, M. O. Oktel
Categories: cond-mat.mes-hall
Comments: 4 pages, 4 figures
   We consider a gas of non-interacting spinless fermions in a rotating optical
lattice and calculate the density profile of the gas in an external confinement
potential. The density profile exhibits distinct plateaus, which correspond to
gaps in the single particle spectrum known as the Hofstadter butterfly. The
plateaus result from insulating behavior whenever the Fermi energy lies within
a gap. We discuss the necessary conditions to realize the Hofstadter insulator
in a cold atom setup and show how the quantized Hall conductance can be
measured from density profiles using the St\v{r}eda formula.
\\ ( , 456kb)
Date: Thu, 22 Nov 2007 13:17:34 GMT (106kb)

Title: EPR argument and Bell inequalities for Bose-Einstein spin condensates
Authors: Franck Lalo\"e (LKB - Lhomond), William J. Mullin (UMASS)
Categories: quant-ph
Proxy: ccsd hal-00189827
   We discuss the properties of two Bose-Einstein condensates in different spin
states, represented quantum mechanically by a double Fock state. Individual
measurements of the spins of the particles are performed in transverse
directions (perpendicular to the spin quantization axis), giving access to the
relative phase of the two macroscopically occupied states. Before the first
spin measurement, the phase is completely undetermined; after a few
measurements, a more and more precise knowledge of its value emerges under the
effect of the quantum measurement process. This naturally leads to the usual
notion of a quasi-classical phase (Anderson phase) and to an interesting
transposition of the EPR (Einstein-Podolsky-Rosen) argument to macroscopic
physical quantities. The purpose of this article is to discuss this
transposition, as well as situations where the notion of a quasi-classical
phase is no longer sufficient to account for the quantum results, and where
significant violations of Bell type inequalities are predicted.
\\ ( , 106kb)
Date: Fri, 23 Nov 2007 14:17:39 GMT (781kb)

Title: Effects of relative phase and interactions on atom-laser outcoupling
   from a double-well Bose-Einstein condensate: Markovian and non-Markovian
Authors: G. M. Nikolopoulos, C. Lazarou, and P. Lambropoulos
Categories: quant-ph
Comments: to appear in J. Phys. B
   We investigate aspects of the dynamics of a continuous atom-laser scheme
based on the merging of independently formed atomic condensates. Our
theoretical analysis covers the Markovian as well as the non-Markovian
operational regimes, and is based on a semiclassical (mean-field) two-mode
model. The role of the relative phase between the two condensates and the
effect of interatomic interactions on the evolution of the trapped populations
and the distribution of outcoupled atoms are discussed.
\\ ( , 781kb)
Date: Fri, 23 Nov 2007 22:35:31 GMT (926kb)

Title: Minimum instances of topological matter in an optical plaquette
Authors: Belen Paredes and Immanuel Bloch
Categories: cond-mat.other
Comments: 8 pages, 11 figures
   We propose experimental schemes to create and probe minimum forms of
different topologically ordered states in a plaquette of an optical lattice:
Resonating Valence Bond, Laughlin and string-net condensed states. We show how
to create anyonic excitations on top of these liquids and detect their
fractional statistics. In addition, we propose a way to design a plaquette
ring-exchange interaction, the building block Hamiltonian of a lattice
topological theory. Our preparation and detection schemes combine different
techniques already demonstrated in experiments with atoms in optical
\\ ( , 926kb)
Date: Sat, 24 Nov 2007 10:19:40 GMT (537kb,D)

Title: Cat state production with ultracold bosons in rotating ring
Authors: Andreas Nunnenkamp, Ana Maria Rey, Keith Burnett
Categories: cond-mat.other
Comments: 9 pages, 10 figures
   Ultracold bosons in rotating ring lattices have previously been shown to form
cat-like superpositions of different quasi-momentum states. We demonstrate that
cat state production in slightly non-uniform ring lattices has several
advantages: the energy gap decreases less severely with the number of
particles, the sensitivity to detunings from the critical rotation frequency is
reduced, and the scheme is not limited to commensurate filling. We show that
different quasi-momentum states can be distinguished in time-of-flight
absorption imaging and propose to probe cat-like correlations via the many-body
oscillations induced by a sudden change in the rotation frequency.
\\ ( , 537kb)
Date: Sun, 25 Nov 2007 13:47:37 GMT (9kb)

Title: On Translational Superfluidity and the Landau Criterion for Trapped Bose
   gases in the Gross-Pitaevski Limit
Authors: Walter F. Wreszinski
Categories: cond-mat.supr-con
Comments: 4 pages, no figures
   A generalised version of the landau superfluidity condition which is adequate
for general (in particular, inhomogeneous, i.e., non translationally invariant)
systems is formulated. Using the (presumably) asymptotic Bogoliubov density
series for the ground state energy of a dilute Bose gas, we show that this
generalised Landau condition is not satisfied by dilute, trapped Bose gases in
the Gross-Pitaevski limit for any regime of flow velocities. we also suggest an
explanation of this fact, and propose that dilute, trapped Bose gases may
provide a unique laboratory to distinguish between the London and Landau
pictures of superfluidity.
\\ ( , 9kb)
Date: Mon, 26 Nov 2007 07:50:06 GMT (459kb)

Title: The iTEBD algorithm beyond unitary evolution
Authors: Roman Orus, Guifre Vidal
Categories: cond-mat.stat-mech
Comments: 11 pages, 15 figures, 1 appendix with algorithms for specific types
   of evolution
   The infinite time-evolving block decimation (iTEBD) algorithm [Phys. Rev.
Lett. 98, 070201 (2007)] allows to simulate unitary evolution and to compute
the ground state of one-dimensional quantum lattice systems in the
thermodynamic limit. Here we extend the algorithm to tackle a much broader
class of problems, namely the simulation of arbitrary one-dimensional evolution
operators that can be expressed as a (translationally invariant) tensor
network. Relatedly, we also address the problem of finding the dominant
eigenvalue and eigenvector of a one-dimensional transfer matrix that can be
expressed in the same way. New applications include the simulation, in the
thermodynamic limit, of open (i.e. master equation) dynamics and thermal states
in 1D quantum systems, as well as calculations with partition functions in 2D
classical systems, on which we elaborate. The present extension of the
algorithm also plays a prominent role in the infinite projected entangled-pair
states (iPEPS) approach to infinite 2D quantum lattice systems.
\\ ( , 459kb)
Date: Mon, 26 Nov 2007 10:10:53 GMT (321kb)

Title: Thermodynamic Evidence for Nanoscale Bose-Einstein Condensation in ^4He
   Confined in Nanoporous Media
Authors: Keiichi Yamamoto, Yoshiyuki Shibayama, Keiya Shirahama
Categories: cond-mat.mes-hall
Comments: 4 pages, 4 figures, submitted to Phys. Rev. Lett
   We report the measurements of the heat capacity of ^4He confined in
nanoporous Gelsil glass that has nanopores of 2.5-nm diameter at pressures up
to 5.3 MPa. The heat capacity has a broad peak at a temperature much higher
than the superfluid transition temperature obtained using the torsional
oscillator technique. The peak provides a definite thermodynamic evidence for
the formation of localized Bose-Einstein condensates (LBECs) on nanometer
length scales. The temperature dependence of heat capacity is well described by
the excitations of phonons and rotons, supporting the existence of LBEC.
\\ ( , 321kb)
Date: Mon, 26 Nov 2007 14:12:03 GMT (613kb)

Title: BEC "level" for measuring small forces
Authors: S. G. Bhongale and Eddy Timmermans
Categories: cond-mat.other
Comments: 4 pages, 4 figures
   We propose a device that consists of a trapped two-component phase- separated
Bose-Einstein condensate to measure small forces and map weak potential energy
landscapes. The resolution as well as the measurement precision of this device
can be set dynamically, allowing measurements at multiple scales.
\\ ( , 613kb)
Date: Mon, 26 Nov 2007 18:02:00 GMT (612kb)

Title: FFLO state in 1, 2, and 3 dimensional optical lattices combined with a
   non-uniform background potential
Authors: T.K. Koponen, T. Paananen, J.-P. Martikainen, M.R. Bakhtiari, and P.
Categories: cond-mat.supr-con cond-mat.str-el
Comments: 18 pages, 10 figures
   We study the phase diagram of an imbalanced two-component Fermi gas in
optical lattices of 1-3 dimensions, considering the possibilities of the FFLO,
Sarma/breached pair, BCS and normal states as well as phase separation, at
finite and zero temperatures. In particular, phase diagrams with respect to
average chemical potential and the chemical potential difference of the two
components are considered, because this gives the essential information about
the shell structures of phases that will occur in presence of an additional
(harmonic) confinement. These phase diagrams in 1, 2 and 3 dimensions show in a
striking way the effect of Van Hove singularities on the FFLO state. Although
we focus on population imbalanced gases, the results are relevant also for the
(effective) mass imbalanced case. We demonstrate by LDA calculations that
various shell structures such as normal-FFLO-BCS-FFLO-normal, or FFLO-normal,
are possible in presence of a background harmonic trap. The phases are
reflected in noise correlations: especially in 1D the unpaired atoms leave a
clear signature of the FFLO state as a zero-correlation area (``breach'')
within the Fermi sea. This strong signature occurs both for a 1D lattice as
well as for a 1D continuum. We also discuss the effect of Hartree energies and
the Gorkov correction on the phase diagrams.
\\ ( , 612kb)
Date: Fri, 23 Nov 2007 23:26:42 GMT (208kb,D)

Title: Unambiguous signatures of entanglement and Bohm's spin EPR paradox
Authors: E. G. Cavalcanti, M. D. Reid, P. D. Drummond, H. A. Bachor
Categories: quant-ph
Comments: 4 pages 3 figures
   We obtain criteria to prove either entanglement or Bohm's spin EPR paradox,
from the observed correlations of bosons with non-ideal generators and
detectors. The signatures can be utilized both for microscopic and macroscopic
correlated sources. For twin photons, the required efficiencies are achievable
with current detectors.
\\ ( , 208kb)
Date: Mon, 26 Nov 2007 03:59:46 GMT (539kb)

Title: Towards a Cold-atom Realization of Quantum Maps with Hofstadter's
   Butterfly Spectrum
Authors: Jiao Wang and Jiangbin Gong (National Univ. of Singapore)
Categories: quant-ph
Comments: 4 pages, 4 figures, under review since Oct. 4
   Quantum systems with Hofstadter's butterfly spectrum are of fundamental
interest to many research areas. Based upon slight modifications of existing
cold-atom experiments, a cold-atom realization of quantum maps with
Hofstadter's butterfly spectrum is proposed. Connections and differences
between our realization and the kicked Harper model are identified. This work
also exposes, for the first time, a simple connection between the kicked Harper
model and the kicked rotor model, the two paradigms of classical and quantum
\\ ( , 539kb)
Date: Tue, 27 Nov 2007 04:06:22 GMT (12kb)

Title: A unified approach to the derivation of work theorems for equilibrium
   and steady-state, classical and quantum Hamiltonian systems
Authors: M. F. Gelin and D. S. Kosov
Categories: cond-mat.stat-mech
   We present a unified and simple method for deriving work theorems for
classical and quantum Hamiltonian systems, both under equilibrium conditions
and in a steady state. Throughout the paper, we adopt the partitioning of the
total Hamiltonian into the system part, the bath part, and their coupling. We
rederive many equalities which are available in the literature and obtain a
number of new equalities for nonequilibrium classical and quantum systems. Our
results can be useful for determining partition functions and (generalized)
free energies through simulations and/or measurements performed on
nonequilibrium systems.
\\ ( , 12kb)
Date: Tue, 27 Nov 2007 13:06:24 GMT (30kb)

Title: Fully frustrated Josephson junction ladders with Mobius boundary
   conditions as topologically protected qubits
Authors: Gerardo Cristofano, Vincenzo Marotta, Adele Naddeo, Giuliano Niccoli
Categories: quant-ph cond-mat.stat-mech
Comments: 21 pages, 2 figures, in print in Phys. Lett. A
Report-no: Napoli DSF-T-16/2007, INFN-NA-16/2007
   We show how to realize a ``protected'' qubit by using a fully frustrated
Josephson Junction ladder (JJL) with Mobius boundary conditions. Such a system
has been recently studied within a twisted conformal field theory (CFT)
approach (Mod. Phys. Lett. A 15 (2000) 1679; Nucl. Phys. B 641 (2002) 547) and
shown to develop the phenomenon of flux fractionalization (Eur. Phys. J. B 49
(2006) 83). The relevance of a ``closed'' geometry has been fully exploited in
relating the topological properties of the ground state of the system to the
presence of half flux quanta and the emergence of a topological order has been
predicted (JSTAT (2005) P03006). In this letter the stability and
transformation properties of the ground states under adiabatic magnetic flux
change are analyzed and the deep consequences on the realization of a solid
state qubit, protected from decoherence, are presented.
\\ ( , 30kb)
Date: Tue, 27 Nov 2007 10:39:02 GMT (155kb)

Title: Generation of polarization entanglement from spatially-correlated
   photons in spontaneous parametric down-conversion
Authors: Ryosuke Shimizu, Takashi Yamaguchi, Yasuyoshi Mitsumori, Hideo Kosaka,
   Keiichi Edamatsu
Categories: quant-ph
Comments: 4 pages, 4 figures
   We propose a novel scheme to generate polarization entanglement from
spatially-correlated photon pairs. We experimentally realized a scheme by means
of a spatial correlation effect in a spontaneous parametric down-conversion and
a modified Michelson interferometer. The scheme we propose in this paper can be
interpreted as a conversion process from spatial correlation to polarization
\\ ( , 155kb)
Date: Tue, 27 Nov 2007 06:06:40 GMT (170kb)

Title: Generating an entangled coherent state of two cavity modes in a
   three-level \Lambda - type atomic system
Authors: Qing-Xia Mu, Yong-Hong Ma and L. Zhou
Categories: quant-ph
Comments: 3 figures
   In this paper, we present a scheme to generate an entangled coherent state by
considering a three-level \Lambda - type atom interacting with a two-mode
cavity driven by classical fields. The two-mode entangled coherent state can be
obtained under large detuning conditions. Considering the cavity decay, an
analytical solution is deduced.
\\ ( , 170kb)
Date: Tue, 27 Nov 2007 14:05:14 GMT (398kb)

Title: Coherent control of light field with electromagnetically induced
   transparency in a dark state Raman coherent tripod system
Authors: YongYao Li, HuaRong Zhang, YongZhu Chen, JianYing Zhou
Categories: quant-ph
   The coherent superposition of two-atomic levels induced by coherent
population trapping is employed in a standard $\Lambda$ type scheme to form a
tripod-like system. A weak probe pulse scanning across the system is shown to
experience a crossover from absorption to transparent and then to
amplification. Consequently the group velocity of the probe pulse can be
controlled to propagate either as a subluminal, a standard, a superluminal or
even a negative speed. It is shown that the propagation behavior of the light
field is entirely determined and controlled by the initial states of the
coherent superposition.
\\ ( , 398kb)
Date: Tue, 27 Nov 2007 15:22:20 GMT (553kb)

Title: Quantum Zeno dynamics and quantum Zeno subspaces
Authors: Paolo Facchi, Giuseppe Marmo and Saverio Pascazio
Categories: quant-ph
Comments: 21 pages, 9 figures. Dedicated to George Sudarshan on the occasion of
   his 75th birthday. Review of the quantum Zeno dynamics in its three different
   formulations. Proposal of a novel experiment in Section 10
   A quantum Zeno dynamics can be obtained by means of frequent measurements,
frequent unitary kicks or a strong continuous coupling and yields a partition
of the total Hilbert space into quantum Zeno subspaces, among which any
transition is hindered. We focus on the "continuous" version of the quantum
Zeno effect and look at several interesting examples. We first analyze these
examples in practical terms, towards applications, then propose a novel
\\ ( , 553kb)
Date: Tue, 27 Nov 2007 18:28:16 GMT (311kb)

Title: Rabi oscillations and excitation trapping in the coherent excitation of
   a mesoscopic frozen Rydberg gas
Authors: Markus Reetz-Lamour, Thomas Amthor, Johannes Deiglmayr, Matthias
Categories: physics.atom-ph
   We demonstrate the coherent excitation of a mesoscopic ensemble of about 100
ultracold atoms to Rydberg states by driving Rabi oscillations from the atomic
ground state. We employ a dedicated beam shaping and optical pumping scheme to
compensate for the small transition matrix element. We study the excitation in
a weakly interacting regime and in the regime of strong interactions. When
increasing the interaction strength by pair state resonances we observe an
increased excitation rate through coupling to high angular momentum states.
This effect is in contrast to the proposed and previously observed
interaction-induced suppression of excitation, the so-called dipole blockade.
\\ ( , 311kb)
Date: Tue, 27 Nov 2007 02:44:55 GMT (176kb)

Title: Broadband optical delay with large dynamic range using atomic dispersion
Authors: M. R. Vanner, R. J. McLean, A. I. Sidorov, P. Hannaford and A. M.
Categories: physics.optics
Comments: 8 pages, 5 figures
   We report on a tunable all-optical delay line for pulses with optical
frequency within the Rb $D_2$ absorption line. Pulses of 10 ns duration are
delayed in a 10 cm hot vapour cell by up to 40 ns where the transmission
reduces to approximately 10%. Using an optical frequency between absorption
components from different isotopes allows the delay to be increased or
decreased by optical pumping with a second laser, producing rapid tuning over a
range more than 40% of the initial delay. We investigate the frequency and
intensity ranges in which this delay line can be realised. Our observations are
in good agreement with a numerical model of the system.
\\ ( , 176kb)
Date: Tue, 27 Nov 2007 23:59:22 GMT (295kb)

Title: Finite temperature phase diagram of a spin-polarized ultracold Fermi gas
   in a highly elongated harmonic trap
Authors: Xia-Ji Liu, Hui Hu, and Peter D. Drummond
Categories: cond-mat.stat-mech
Comments: 7 pages and 6 figures;
   We investigate the finite temperature properties of an ultracold atomic Fermi
gas with spin population imbalance in a highly elongated harmonic trap.
Previous studies at zero temperature showed that the gas stays in an exotic
spatially inhomogeneous Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluid
state at the trap center; while moving to the edge, the system changes into
either a non-polarized Bardeen-Cooper-Schriffer superfluid ($P<P_c$) or a fully
polarized normal gas ($P>P_c$), depending on the smallness of the spin
polarization $P$, relative to a critical value $P_c$. In this work, we show how
these two phase-separation phases evolve with increasing temperature, and
thereby construct a finite temperature phase diagram. For typical interactions,
we find that the exotic FFLO phase survives below one-tenth of Fermi degeneracy
temperature, which seems to be accessible in the current experiment. The
density profile, equation of state, and specific heat of the polarized system
have been calculated and discussed in detail. Our results are useful for the
on-going experiment at Rice University on the search for FFLO states in
quasi-one-dimensional polarized Fermi gases.
\\ ( , 295kb)
Date: Wed, 28 Nov 2007 06:54:46 GMT (639kb)

Title: The stability and free expansion of a dipolar Fermi gas
Authors: L. He, J.-N. Zhang, Yunbo Zhang, S. Yi
Categories: cond-mat.other
Comments: 5 pages, 5 figures
   We investigate the stability and the free expansion of a trapped dipolar
Fermi gas. We show that stabilizing the system relying on tuning the trap
geometry is generally inefficient. We further show that the expanded density
profile always gets stretched along the attractive direction of dipolar
interaction. We also point out that by switching off the dipolar interaction
simultaneously with the trapping potential, the deformation of momentum
distribution can be directly observed.
\\ ( , 639kb)
Date: Wed, 28 Nov 2007 10:13:19 GMT (410kb)

Title: Bose-Fermi Pair Correlations in Attractively Interacting Bose-Fermi
   Atomic Mixtures
Authors: Takayuki Watanabe, Toru Suzuki and Peter Schuck
Categories: cond-mat.other cond-mat.stat-mech
Comments: 14 pages, 27 figures
   We study static properties of attractively interacting Bose-Fermi mixtures of
uniform atomic gases at zero temperature. Using Green's function formalism we
calculate boson-fermion scattering amplitude and fermion self-energy in the
medium to lowest order of the hole line expansion. We study ground state energy
and pressure as functions of the scattering length for a few values of the
boson-fermion mass ratio $m_b/m_f$ and the number ratio $N_b/N_f$. We find that
the attractive contribution to energy is greatly enhanced for small values of
the mass ratio. We study the role of the Bose-Fermi pair correlations in the
mixture by calculating the pole of the boson-fermion scattering amplitude in
the medium. The pole shows a standard quasiparticle dispersion for a Bose-Fermi
pair, for $m_b/m_f\geq 1$. For small values of the mass ratio, on the other
hand, a Bose-Fermi pair with a finite center-of-mass momentum experiences a
strong attraction, implying large medium effects. In addition, we also study
the fermion dispersion relation. We find two dispersion branches with the
possibility of the avoided crossings. This strongly depends on the number rario
\\ ( , 410kb)
Date: Wed, 28 Nov 2007 15:35:41 GMT (119kb)

Title: Non-local density correlations as signal of Hawking radiation in BEC
   acoustic black holes
Authors: Roberto Balbinot, Alessandro Fabbri and Serena Fagnocchi
Categories: cond-mat.other gr-qc
Comments: 4 pages, 3 eps figures
   Using the analogy between gravitational systems and non-homogeneous fluid
flows, it is possible to use Bose Einstein condensates in hydrodynamical regime
as laboratory to test an effect of otherwise extremely difficult detection,
namely Hawking radiation. We propose to observe it via a non-local density
correlations measurement. Estimates of this effect are given.
\\ ( , 119kb)
Date: Wed, 28 Nov 2007 08:20:18 GMT (206kb)

Title: Two-mode Bose-Einstein condensate in a high-frequency "off-diagonal"
   driving field
Authors: Qi Zhang, Peter Hanggi, and Jiangbin Gong (National Univ. of
Categories: quant-ph
Comments: 4 pages, 4 figures
   A two-mode Bose-Einstein condensate coupled by a high-frequency driving field
is found to display remarkable features. An effective stationary Hamiltonian
approach reveals the emergence of additional degenerate eigenstates as well as
new topological structures of the spectrum. Possible applications, including
the suppression of nonlinear Landau-Zener tunneling, are discussed. An
interesting phenomenon, which we call ``deterministic symmetry-breaking
trapping", is also found in an adiabatic process. Results suggest that a
high-frequency field applied to a Bose-Einstein condensate can induce
unexpected, very rich dynamical phenomena.
\\ ( , 206kb)
Date: Wed, 28 Nov 2007 05:23:47 GMT (161kb)

Title: A pumped atom laser
Authors: N. P. Robins, C. Figl, M. Jeppesen, G. R. Dennis and J. D. Close
Categories: physics.atom-ph
Comments: 15 pages, 4 figures
   We present the experimental realization of a pumped atom laser. We
demonstrate the pumping through measurements of the source and laser-mode atom
numbers, making a rate equation study of the pumping process.
\\ ( , 161kb)
Date: Wed, 28 Nov 2007 19:35:28 GMT (94kb)

Title: Guide for atomic and particle physicists to CODATA's recommended values
   of the fundamental physical constants
Authors: Savely G. Karshenboim
Categories: physics.atom-ph
Comments: presented at PSAS'2006; to be pubslished in Lect. Not. Phys
   The CODATA recommended values of the fundamental constants are widely applied
in particle, nuclear and atomic physics. They are a result of a complicated
evaluation (adjustment) of numerous correlated data of different nature. Their
application is often rather mechanical and as a result is not free of various
confusions which are discussed in this note.
\\ ( , 94kb)
Date: Wed, 28 Nov 2007 21:08:20 GMT (263kb)

Title: P-wave Pairing in Two-Component Fermi Systems with Unequal Population
   near Feshbach Resonance
Authors: R. Liao, F. Popescu, K. Quader
Categories: cond-mat.supr-con cond-mat.other
Comments: 5 pages, 3 figures
   We explore p-wave pairing in a single-channel two-component Fermi system with
unequal population near Feshbach resonance. Our analytical and numerical study
reveal a rich superfluid (SF) ground state structure as a function of
imbalance. In addition to the state $\Delta_{\pm 1} \propto Y_{1\pm 1}$, a
multitude of ``mixed'' SF states formed of linear combinations of $Y_{1m}$'s
give global energy minimum under a phase stability condition; these states
exhibit variation in energy with the relative phase between the constituent gap
amplitudes. States with local energy minimum are also obtained. We provide a
geometric representation of the states. A $T$=0 polarization vs. p-wave
coupling phase diagram is constructed across the BEC-BCS regimes. With
increased polarization, the global minimum SF state may undergo a quantum phase
transition to the local minimum SF state.
\\ ( , 263kb)
Date: Thu, 29 Nov 2007 20:32:17 GMT (35kb)

Title: Superfluid and Mott Insulator phases of one-dimensional Bose-Fermi
Authors: A. Zujev, A. Baldwin, R. T. Scalettar, V. G. Rousseau, P. J. H.
   Denteneer, M. Rigol
Categories: cond-mat.stat-mech
Comments: 7 pages, 11 figures
   We study the ground state phases of Bose-Fermi mixtures in one-dimensional
optical lattices with quantum Monte Carlo simulations using the Canonical Worm
algorithm. Depending on the filling of bosons and fermions, and the on-site
intra- and inter-species interaction, different kinds of incompressible and
superfluid phases appear. On the compressible side, correlations between bosons
and fermions can lead to a distinctive behavior of the bosonic superfluid
density and the fermionic stiffness, as well as of the equal-time Green
functions, which allow one to identify regions where the two species exhibit
anticorrelated flow. We present here complete phase diagrams for these systems
at different fillings and as a function of the interaction parameters.
\\ ( , 35kb)
Date: Thu, 29 Nov 2007 14:26:46 GMT (595kb)

Title: Bogoliubov theory of quantum correlations in the time-dependent
   Bose-Hubbard model
Authors: Uwe R. Fischer, Ralf Sch\"utzhold, Michael Uhlmann
Categories: cond-mat.other
Comments: 9 pages of RevTex4, 2 figures
   By means of an adapted mean-field expansion for large fillings n>>1, we study
the evolution of quantum fluctuations in the time-dependent Bose-Hubbard model,
starting in the superfluid state and approaching the Mott phase by decreasing
the tunneling rate or increasing the interaction strength in time. For two
experimentally relevant cases, we derive analytical results for the freezing
and growth of the number and phase fluctuations, respectively. This allows us
to calculate the temporal growth of the quantum depletion and the decay of
off-diagonal long-range order. We estimate the conditions for the observability
of the time dependence in the correlation functions in the experimental setups
with external trapping present. Finally, we discuss the analogy to quantum
effects in the early universe during the inflationary epoch.
\\ ( , 595kb)
Date: Thu, 29 Nov 2007 14:30:04 GMT (34kb)

Title: Competing Orders in One-Dimensional Half-Integer Fermionic Cold Atoms: A
   Conformal Field Theory Approach
Authors: P. Lecheminant, P. Azaria, and E. Boulat
Categories: cond-mat.str-el
Comments: 35 pages, 3 figures
   The physical properties of arbitrary half-integer spins F = N - 1/2 fermionic
cold atoms loaded into a one-dimensional optical lattice are investigated by
means of a conformal field theory approach. We show that for attractive
interactions two different superfluid phases emerge for F \ge 3/2: A BCS
pairing phase, and a molecular superfluid phase which is formed from
bound-states made of 2N fermions. In the low-energy approach, the competition
between these instabilities and charge-density waves is described in terms of
Z_N parafermionic degrees of freedom. The quantum phase transition for
F=3/2,5/2 is universal and shown to belong to the Ising and three-state Potts
universality classes respectively. For a filling of one atom per site, a Mott
transition occurs and the nature of the possible Mott-insulating phases are
\\ ( , 34kb)
Date: Thu, 29 Nov 2007 16:06:47 GMT (13kb)

Title: Generalized Galitskii approach for the vertex function of a Fermi gas
   with resonant interaction
Authors: A. Vagov, H. Schomerus, A. Shanenko
Categories: cond-mat.other
Comments: 7 pages, to appear in Physical Review B
   We present a generalized Galitskii approach for the Bethe-Salpeter equation
for the two-particle vertex function of a Fermi system with resonant
interaction by accounting for the resonant state in the scattering potential
and utilizing the universal form of the resonant scattering amplitude. The
procedure can be carried out both for the normal as well as for the condensate
state. In both cases, the vertex function in the vicinity of the resonance is
shown to formally coincide with that obtained for a weakly attractive Fermi
gas. Thus we justify the popular calculational framework in which results for
the weakly attractive Fermi gas are formally extrapolated into the domain of
strong coupling, and further to the repulsive side of the resonance, where
molecular states are formed.
\\ ( , 13kb)
Date: Wed, 28 Nov 2007 22:46:17 GMT (43kb)

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
   The equation of state of the partially polarized two component Fermi gas at
zero temperature in the unitary limit is computed by {\it ab initio} auxiliary
field Monte Carlo method. We obtain the critical ratio of the chemical
potentials $\mu_\downarrow/\mu_\uparrow$ at the phase transitions. The value of
$\mu_\downarrow/\mu_\uparrow$ at the transition between the fully paired
superfluid and the partially polarized phase is 0.11 while the critical value
for the phase transition between the partially polarized phase and the fully
polarized normal fluid is -0.59. We also determine the radial boundaries of the
phase transitions of the Fermi gas in the harmonic trap as function of the
total polarization. We find that beyond the critical polarization 0.65, the
fully paired superfluid core disappears in the trapped Fermi gas.
\\ ( , 43kb)
Date: Thu, 29 Nov 2007 01:21:42 GMT (341kb)

Title: Trapping of Neutral Mercury Atoms and Prospects for Optical Lattice
Authors: H. Hachisu, K. Miyagishi, S.G. Porsev, A. Derevianko, V. D.
   Ovsiannikov, V. G. Pal'chikov, M. Takamoto, H. Katori
Categories: physics.atom-ph
Comments: 4 pages, 3 figures
   We report a vapor-cell magneto-optical trapping of Hg isotopes on the
${}^1S_0-{}^3P_1$ intercombination transition. Six abundant isotopes, including
four bosons and two fermions, were trapped. Hg is the heaviest non-radioactive
atom trapped so far, which enables sensitive atomic searches for ``new
physics'' beyond the standard model. We propose an accurate optical lattice
clock based on Hg and evaluate its systematic accuracy to be better than
$10^{-18}$. Highly accurate and stable Hg-based clocks will provide a new
avenue for the research of optical lattice clocks and the time variation of the
fine-structure constant.
\\ ( , 341kb)
Date: Thu, 29 Nov 2007 08:05:48 GMT (368kb)

Title: A magnetic lens for cold atoms controlled by a rf field
Authors: E. Marechal (LPL), B. Laburthe-Tolra (LPL), L. Vernac (LPL), J. -C.
   Keller (LPL), O. Gorceix (LPL)
Categories: physics.atom-ph
Proxy: ccsd hal-00192598
   We report on a new type of magnetic lens that focuses atomic clouds using a
static inhomogeneous magnetic field in combination with a radio-frequency
field. The experimental study is performed with a cloud of cold cesium atoms.
The rf field adiabatically deforms the magnetic potential of a coil and
therefore changes its focusing properties. The focal length can be tuned
precisely by changing the rf frequency value. Depending on the rf antenna
position relative to the DC magnetic profile, the focal length of the atomic
lens can be either decreased or increased by the rf field.
\\ ( , 368kb)

The replacements:

replaced with revised version Thu, 22 Nov 2007 07:51:18 GMT (21kb)

Title: Decoherence of a particle in a ring
Authors: Doron Cohen and Baruch Horovitz
Categories: cond-mat.mes-hall
Comments: 5 pages, 1 figure, proofed version to be published in EPL
\\ ( , 21kb)
replaced with revised version Thu, 22 Nov 2007 04:43:32 GMT (5kb)

Title: Higher order terms in the condensate fraction of a homogeneous and
   dilute Bose gas
Authors: Sang-Hoon Kim
Categories: cond-mat.stat-mech
Comments: 5 pages, 0 figure
\\ ( , 5kb)
replaced with revised version Fri, 23 Nov 2007 17:32:38 GMT (59kb)

Title: Quantum Phase Transition in a Cold Atomic Spin-Boson Mixture
Authors: Peter P. Orth, Ivan Stanic, Karyn Le Hur
Categories: cond-mat.other
Comments: 4 pages, 2 figures, 1 table
\\ ( , 59kb)
replaced with revised version Thu, 22 Nov 2007 13:09:35 GMT (0kb,I)

Title: Comment on PRL 99,140402 (2007) "Excitations in a nonequilibrium Bose
   Einstein Condensate of Exciton-polaritons" by M. Wouters and I. Carusotto
Authors: G. Malpuech, D.D. Solnyshkov, I.A. Shelykh
Categories: cond-mat.mes-hall
Comments: This comment has been withdrawn
\\ ( , 0kb)
replaced with revised version Thu, 22 Nov 2007 00:05:40 GMT (184kb)

Title: Probing quantum phases of ultracold atoms in optical lattices by
   transmission spectra in cavity QED
Authors: Igor. B. Mekhov, Christoph Maschler, Helmut Ritsch
Categories: quant-ph physics.atom-ph physics.optics
Comments: 6 pages, 3 figures
Journal-ref: Nature Phys. 3, 319 (2007)
DOI: 10.1038/nphys571
\\ ( , 184kb)
replaced with revised version Thu, 22 Nov 2007 17:09:32 GMT (278kb)

Title: Dynamics, dephasing and clustering of impurity atoms in Bose-Einstein
Authors: Alexander Klein, Martin Bruderer, Stephen R. Clark, and Dieter Jaksch
Categories: quant-ph
Comments: 22 pages, 8 figures, some typos corrected
Journal-ref: New J. Phys. 9, 411 (2007)
DOI: 10.1088/1367-2630/9/11/411
\\ ( , 278kb)
replaced with revised version Sat, 24 Nov 2007 07:50:42 GMT (14kb)

Title: Bell inequalities for continuous-variable correlations
Authors: E. G. Cavalcanti, C. J. Foster, M. D. Reid and P. D. Drummond
Categories: quant-ph
Comments: 4 pages, 1 figure. v2: New results on detector efficiencies and
   macroscopic limit, new co-author, changed title and abstract, changed figure,
   added journal reference and DOI
Journal-ref: Phys. Rev. Lett. 99, 210405 (2007)
DOI: 10.1103/PhysRevLett.99.210405
\\ ( , 14kb)
replaced with revised version Mon, 26 Nov 2007 07:57:19 GMT (69kb)

Title: Universal geometric entanglement close to quantum phase transitions
Authors: Roman Orus
Categories: quant-ph cond-mat.str-el hep-th
Comments: 4 pages, 3 figures
\\ ( , 69kb)
replaced with revised version Tue, 27 Nov 2007 20:29:50 GMT (421kb)

Title: Anyonic Braiding in Optical Lattices
Authors: Chuanwei Zhang, V.W. Scarola, Sumanta Tewari and S. Das Sarma
Categories: quant-ph cond-mat.other cond-mat.soft
Comments: 22 pages, 5 figures, published version
Journal-ref: Proc. Natl. Acad. Sci. USA 104, 18415 (2007)
\\ ( , 421kb)
replaced with revised version Tue, 27 Nov 2007 09:02:49 GMT (307kb)

Title: Quantum Superposition State Production by Continuous Observations and
Authors: Antonio Negretti, Uffe V. Poulsen, Klaus Molmer
Categories: quant-ph
Comments: RevTex4, 4 pages, 2 figures. Published in Phys. Rev. Lett. with
   higher quality figures. The first part of the manuscript, regarding the Fock
   state generator, has been removed
Journal-ref: Phys. Rev. Lett. 99, 223601 (2007)
\\ ( , 307kb)
replaced with revised version Tue, 27 Nov 2007 18:15:19 GMT (115kb)

Title: Controlling the Ratchet Effect for Cold Atoms
Authors: Anatole Kenfack, Jiangbin Gong and Arjendu K. Pattanayak
Categories: quant-ph
Comments: 4 pages, 4 figures
\\ ( , 115kb)
replaced with revised version Tue, 27 Nov 2007 16:33:35 GMT (387kb)

Title: Compression and localization of an atomic cloud in a time dependent
   optical lattice
Authors: Will Williams, M. Saffman
Categories: physics.atom-ph
Comments: 11 Figures Revised Manuscript
\\ ( , 387kb)
replaced with revised version Wed, 28 Nov 2007 01:55:24 GMT (369kb)

Title: Spatial pair correlations of atoms in molecular dissociation
Authors: C.M. Savage and K.V. Kheruntsyan
Categories: cond-mat.other
Comments: Final published version
Journal-ref: Phys. Rev. Lett. 99, 220404 (2007)
DOI: 10.1103/PhysRevLett.99.220404
\\ ( , 369kb)
replaced with revised version Wed, 28 Nov 2007 15:22:32 GMT (40kb,D)

Title: Generalized ABCD propagation for interacting atomic clouds
Authors: F. Impens and Ch. J. Bord\'e
Categories: cond-mat.other
Comments: 10 pages, 2 figures. A new relativistic formulation of the ABCD
   formalism in (4+1) dimensions has been added
\\ ( , 40kb)
replaced with revised version Wed, 28 Nov 2007 13:48:36 GMT (430kb)

Title: Loschmidt cooling by time reversal of atomic matter waves
Authors: J. Martin, B. Georgeot, D. L. Shepelyansky (CNRS, Toulouse)
Categories: cond-mat.stat-mech nlin.CD quant-ph
Comments: revtex 4 pages, 5 figs, research at, new data and modifications added
\\ ( , 430kb)
replaced with revised version Thu, 29 Nov 2007 16:46:04 GMT (661kb)

Title: Absence of fermionic quasi-particles in the superfluid state of the
   attractive Fermi gas
Authors: Nils Lerch, Lorenz Bartosch, and Peter Kopietz
Categories: cond-mat.supr-con cond-mat.str-el
Comments: 4 RevTex pages, 3 figures; title changed, new Figure 1, added
   references. We argue that in the entire regime of the BCS-BEC crossover the
   quasi-particle picture breaks down in D <=3 for neutral fermions (but NOT for
   charged fermions)
\\ ( , 661kb)

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 Thu Dec 20 2007 - 14:52:45 EST

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