[Matts-arxiv] Matt's arXiv selection: week ending 26 June 2009

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Fri, 21 Aug 2009 13:51:58 +1000

Dear subscribers,

Things have fallen behind again, but I am hoping my team of helpers will have us
up to date again soon. This week's list was compiled by Dr Andy Ferris (who
deserves congratulations for officially receiving his PhD just this week!)

This week there are 31 new preprints and 10 replacements:

Date: Thu, 18 Jun 2009 20:44:16 GMT (147kb)

Title: Haldane charge conjecture in one-dimensional multicomponent fermionic
   cold atoms
Authors: H. Nonne, P. Lecheminant, S. Capponi, G. Roux, E. Boulat
Categories: cond-mat.str-el cond-mat.quant-gas
Comments: 4 pages, 4 figures
   A Haldane conjecture is revealed for spin-singlet charge modes in
2N-component fermionic cold atoms loaded into one-dimensional optical lattice.
By means of a low-energy approach and DMRG calculations, we show the emergence
of gapless and gapped phases depending on the parity of N for attractive
interactions at half-filling. In particular, the analogue of the Haldane phase
of the spin-1 Heisenberg chain is stabilized for N = 2 with non-local string
charge correlation, and pseudo-spin 1/2 edge states. At the heart of this
even-odd behavior is the existence of spin-singlet pseudo-spin N/2 operator
which governs the low-energy properties of the model for attractive
interactions and give rise to the Haldane physics.
\\ ( http://arxiv.org/abs/0906.3528 , 147kb)
Date: Fri, 19 Jun 2009 03:21:01 GMT (1212kb)

Title: Vortices in $p$-Wave Superfluids of Trapped Fermionic Atom Gases
Authors: Y. Tsutsumi, K. Machida
Categories: cond-mat.supr-con cond-mat.quant-gas
Comments: 17 pages, 9 figures, to be published in J. Phys. Soc. Jpn
   In order to help detecting superfluidity, we theoretically investigate p-wave
pairing superfluids in neutral Fermion atom gases confined by a three
dimensimentional (3D) harmonic potential. The Ginzburg-Landau framework, which
is generic for p-wave superfluids, is used to describe the order parameter
spatial structure, or texture characterized by the $l$-vector both at rest and
under rotation. The $l$-vector configuration is strongly contrained by the
boundary condition due to a trap. It is found that the ground state textures
exhibit spontaneous supercurrent at rest both cigar and pancake shape traps.
The current direction depends on the trapping shape. Under rotation a pair of
half-quantum vortex with half-winding number enters a system and is stabilized
for both trap geometries. We give detailed explanation for their 3D structure.
The deformations of the condensate shape are seen with increasing the rotation
speed, which is tightly connected with the underlying vortex formation where
the condensates are depressed in the vortex core.
\\ ( http://arxiv.org/abs/0906.3564 , 1212kb)
Date: Fri, 19 Jun 2009 14:52:48 GMT (2291kb)

Title: Controlled localization of interacting bosons in a disordered optical
Authors: J. Santos, R. A. Molina, J. Ortigoso and M. Rodriguez
Categories: cond-mat.quant-gas
Comments: 5 pages 6 figs
   We show how a fast oscillatory force can be used to control the localization
properties of interacting bosons trapped in a disordered optical lattice. By
adiabatically increasing the amplitude of the external driving force one can
induce a transition from superfluid to insulating states such as a Bose-Glass
or a Mott-insulator or, for strong disorder, from an Anderson-Glass to a
Bose-Glass. Within the disordered Bose-Hubbard model, we show that this method
can be used to explore in a controlled way the entire phase diagram of bosons
in the presence of disorder and interactions.
\\ ( http://arxiv.org/abs/0906.3687 , 2291kb)
Date: Thu, 18 Jun 2009 20:37:05 GMT (475kb)

Title: Experimental quantum-enhanced estimation of a lossy phase shift
Authors: M. Kacprowicz, R. Demkowicz-Dobrzanski, W. Wasilewski, K. Banaszek, I.
   A. Walmsley
Categories: quant-ph
Comments: 5 pages
   When standard light sources are employed, the precision of the phase
determination is limited by the shot noise. Quantum entanglement provides means
to exceed this limit with the celebrated example of N00N states that saturate
the ultimate Heisenberg limit on precision, but at the same time are extremely
fragile to losses. In contrast, we provide experimental evidence that
appropriately engineered quantum states outperform both standard and N00N
states in the precision of phase estimation when losses are present.
\\ ( http://arxiv.org/abs/0906.3511 , 475kb)
Date: Fri, 19 Jun 2009 13:30:37 GMT (1363kb)

Title: One-Dimensional Optical Lattice Clock with a Fermionic 171Yb Isotope
Authors: Takuya Kohno, Masami Yasuda, Kazumoto Hosaka, Hajime Inaba, Yoshiaki
   Nakajima, Feng-Lei Hong
Categories: physics.atom-ph physics.optics
Comments: 11 pages, 5 figures, Appl. Phys. Express (Open Select Paper: open
Journal-ref: Appl. Phys. Express 2 (2009) 072501
DOI: 10.1143/APEX.2.072501
   We demonstrate a one-dimensional optical lattice clock with ultracold 171Yb
atoms, which is free from the linear Zeeman effect. The absolute frequency of
the 1S0(F = 1/2) - 3P0(F = 1/2) clock transition in 171Yb is determined to be
518 295 836 590 864(28) Hz with respect to the SI second.
\\ ( http://arxiv.org/abs/0906.3664 , 1363kb)
Date: Mon, 22 Jun 2009 00:10:32 GMT (384kb,P)

Title: Zero Sound in Dipolar Fermi Gases
Authors: Shai Ronen and John Bohn
Categories: cond-mat.quant-gas
   We study the propagation of sound in a homogeneous dipolar gas at zero
temperature, known as zero sound. We find that below a critical dipolar
interaction, undamped sound propagation is possible only in a range of solid
angles around the direction of polarization of the dipoles. For larger
interaction strength, zero sound propagates in all directions, but its nature
changes as a function of direction. In particular, there appears a transverse
mode for the perpendicular propagation direction, which resembles the
transverse mode in liquid He-3. We explain how these properties arise as a
result of the anisotropic dipolar interaction.
\\ ( http://arxiv.org/abs/0906.3753 , 384kb)
Date: Sat, 20 Jun 2009 04:06:09 GMT (5kb)

Title: Do bosons obey Bose-Einstein distribution: two iterated limits of
   Gentile distribution
Authors: Wu-Sheng Dai and Mi Xie
Categories: cond-mat.stat-mech
Comments: 6 pages, no figure
Journal-ref: Physics Letters A 373 (2009) 1524
   It is a common impression that by only setting the maximum occupation number
to infinity, which is the demand of the indistinguishability of bosons, one can
achieve the statistical distribution that bosons obey -- the Bose-Einstein
distribution. In this letter, however, we show that only with an infinite
maximum occupation number one cannot uniquely achieve the Bose-Einstein
distribution, since in the derivation of the Bose-Einstein distribution, the
problem of iterated limit is encountered. For achieving the Bose-Einstein
distribution, one needs to take both the maximum occupation number and the
total number of particles to infinities, and, then, the problem of the order of
taking limits arises. Different orders of the limit operations will lead to
different statistical distributions. For achieving the Bose-Einstein
distribution, besides setting the maximum occupation number, we also need to
state the order of the limit operations.
\\ ( http://arxiv.org/abs/0906.3777 , 5kb)
Date: Mon, 22 Jun 2009 02:03:51 GMT (13kb)

Title: Numerical representation of quantum states in the positive-P and Wigner
Authors: M. K. Olsen and A. S. Bradley
Categories: cond-mat.quant-gas
Comments: 16 pages, single column format
   Numerical stochastic integration is a powerful tool for the investigation of
quantum dynamics in interacting many body systems. As with all numerical
integration of differential equations, the initial conditions of the system
being investigated must be specified. With application to quantum optics in
mind, we show how various commonly considered quantum states can be numerically
simulated by the use of widely available Gaussian and uniform random number
generators. We note that the same methods can also be applied to computational
studies of Bose-Einstein condensates, and give some examples of how this can be
\\ ( http://arxiv.org/abs/0906.3905 , 13kb)
Date: Mon, 22 Jun 2009 11:09:01 GMT (268kb)

Title: Adiabatic Splitting, Transport, and Self-Trapping of a Bose-Einstein
   Condensate in a Double-Well Potential
Authors: C. Ottaviani, V. Ahufinger, R. Corbal\'an, and J. Mompart
Categories: cond-mat.quant-gas
Comments: 8 pages and 7 figures
   We show that the adiabatic dynamics of a Bose-Einstein condensate (BEC) in a
double well potential can be described in terms of a dark variable resulting
from the combination of the population imbalance and the spatial atomic
coherence between the two wells. By means of this dark variable, we extend, to
the non-linear matter wave case, the recent proposal by Vitanov and Shore
[Phys. Rev. A 73, 053402 (2006)] on adiabatic passage techniques to coherently
control the population of two internal levels of an atom/molecule. We
investigate the conditions to adiabatically split or transport a BEC as well as
to prepare an adiabatic self trapping state by the optimal delayed temporal
variation of the tunneling rate via either the energy bias between the two
wells or the BEC non-linearity. The emergence of non-linear eigenstates and
unstable stationary solutions of the system as well as their role in the
breaking down of the adiabatic dynamics is investigated in detail.
\\ ( http://arxiv.org/abs/0906.3976 , 268kb)
Date: Mon, 22 Jun 2009 11:30:57 GMT (46kb)

Title: Pseudogap in fermionic density of states in the BCS-BEC crossover of
   atomic Fermi gases
Authors: S. Tsuchiya, R. Watanabe, and Y. Ohashi
Categories: cond-mat.quant-gas
Comments: 6 pages, 4 figures, Proceedings of QFS 2009
   We study pseudogap behaviors of ultracold Fermi gases in the BCS-BEC
crossover region. We calculate the density of states (DOS), as well as the
single-particle spectral weight, above the superfluid transition temperature
$T_{\rm c}$ including pairing fluctuations within a $T$-matrix approximation.
We find that DOS exhibits a pseudogap structure in the BCS-BEC crossover
region, which is most remarkable near the unitarity limit. We determine the
pseudogap temperature $T^*$ at which the pseudogap structure in DOS disappears.
We also introduce another temperature $T^{**}$ at which the BCS-like
double-peak structure disappears in the spectral weight. While one finds
$T^*>T^{**}$ in the BCS regime, $T^{**}$ becomes higher than $T^*$ in the
crossover and BEC regime. We also determine the pseudogap region in the phase
diagram in terms of temperature and pairing interaction.
\\ ( http://arxiv.org/abs/0906.3983 , 46kb)
Date: Mon, 22 Jun 2009 13:05:09 GMT (90kb)

Title: Transport in a Luttinger liquid with dissipation: two impurities
Authors: Leiming Chen, Zoran Ristivojevic, and Thomas Nattermann
Categories: cond-mat.str-el cond-mat.dis-nn
Comments: 11 pages, 3 figures
   We consider theoretically the transport in a one-channel spinless Luttinger
liquid with two strong impurities in the presence of dissipation. As a
difference with respect to the dissipation free case, where the two impurities
fully transmit electrons at resonance points, the dissipation prevents complete
transmission in the present situation. A rich crossover diagram for the
conductance as a function of applied voltage, temperature, dissipation
strength, Luttinger liquid parameter K and the deviation from the resonance
condition is obtained. For weak dissipation and 1/2<K<1, the conduction shows a
non-monotonic increase as a function of temperature or voltage. For strong
dissipation the conduction increases monotonically but is exponentially small.
\\ ( http://arxiv.org/abs/0906.3995 , 90kb)
arXiv:0902.4623 (*cross-listing*)
Date: Thu, 26 Feb 2009 16:27:00 GMT (8kb)
Date (revised v2): Mon, 9 Mar 2009 18:51:47 GMT (24kb)
Date (revised v3): Mon, 22 Jun 2009 08:44:56 GMT (24kb)

Title: Fidelity susceptibility and quantum adiabatic condition in thermodynamic
Authors: Shi-Jian Gu
Categories: quant-ph cond-mat.str-el
Comments: 4 pages, final version accepted by PRE
   In this work, we examine the validity of quantum adiabatic theorem in
thermodynamic systems. For a $d$-dimensional quantum many-body system, we show
that the duration time $\tau_0$ required by its ground-state adiabatic process
does not depend on the microscopic details, but the scaling dimension of the
fidelity susceptibility $d_a$. Our result, therefore, provides a quantitative
time scale of the quantum adiabatic theorem in thermodynamic systems. The
quantum adiabatic theorem might be violated in case that the scaling dimension
of the fidelity susceptibility is larger than the system's real dimension
\\ ( http://arxiv.org/abs/0902.4623 , 24kb)
Date: Mon, 22 Jun 2009 16:04:10 GMT (1962kb)

Title: Atom-ion quantum gate
Authors: Hauke Doerk-Bendig, Zbigniew Idziaszek and Tommaso Calarco
Categories: quant-ph
Comments: submitted to Phys. Rev. A
   We study ultracold collisions of ions with neutral atoms in traps. Recently,
ultracold atom-ion systems are becoming available in experimental setups, where
their quantum states can be coherently controlled. This allows for an
implementation of quantum information processing combining the advantages of
charged and neutral particles. The state-dependent dynamics that is a necessary
ingredient for quantum computation schemes is provided in this case by the
short-range interaction forces depending on hyperfine states of both particles.
   In this work we develop a theoretical description of spin-state-dependent
trapped atom-ion collisions in the framework of a Multichannel Quantum Defect
Theory (MQDT) and formulate an effective single channel model that reduces the
complexity of the problem.
   Based on this description we simulate a two-qubit phase gate between a Ba135+
ion and a Rb87 atom using a realistic combination of the singlet and triplet
scattering lengths. We optimize and accelerate the gate process with the help
of optimal control techniques. Our result is a gate fidelity 0.999 within 350
\\ ( http://arxiv.org/abs/0906.3779 , 1962kb)
Date: Mon, 22 Jun 2009 07:29:43 GMT (79kb)

Title: On coherence lengths of wave packets I
Authors: Kenzo Ishikawa and Yutaka Tobita
Categories: quant-ph
Comments: 27 pages,3 figures
Report-no: EPHOU-09-002
   Coherence lengths of one particle states described by quantum wave functions
are studied. We show that one particle states in various situations are not
described by simple plane waves but are described by wave packets that are
superpositions of plane waves. Wave packet is an approximate eigenstate of the
free Hamiltonian and has a finite spatial size which we call the coherence
length. The coherence lengths in the coordinate space and in the momentum space
are studied in the present paper. We investigate several mechanisms of forming
wave packets, stabilities of wave packets, and transformations of wave packets.
\\ ( http://arxiv.org/abs/0906.3938 , 79kb)
Date: Tue, 23 Jun 2009 13:42:39 GMT (220kb)

Title: Vortices in dipolar condensates with dominant dipolar interactions
Authors: M. Abad, M. Guilleumas, R. Mayol, M. Pi, and D. M. Jezek
Categories: cond-mat.quant-gas
Comments: 10 pages with 9 figures
Journal-ref: Phys. Rev. A 79, 063622 (2009)
DOI: 10.1103/PhysRevA.79.063622
   We present full three-dimensional numerical calculations of single vortex
states in rotating dipolar condensates. We consider a Bose-Einstein condensate
of 52Cr atoms with dipole-dipole and s-wave contact interactions confined in an
axially symmetric harmonic trap. We obtain the vortex states by numerically
solving the Gross-Pitaevskii equation in the rotating frame with no further
approximations. We investigate the properties of a single vortex and calculate
the critical angular velocity for different values of the s-wave scattering
length. We show that, whereas the standard variational approach breaks down in
the limit of pure dipolar interactions, exact solutions of the Gross-Pitaevskii
equation can be obtained for values of the s-wave scattering length down to
zero. The energy barrier for the nucleation of a vortex is calculated as a
function of the vortex displacement from the rotation axis for different values
of the angular velocity of the rotating trap.
\\ ( http://arxiv.org/abs/0906.4259 , 220kb)
Date: Tue, 23 Jun 2009 16:28:31 GMT (15kb)

Title: BCS-BEC crossover with unequal mass fermions
Authors: Roberto B. Diener and Mohit Randeria
Categories: cond-mat.quant-gas
Comments: 4 pages, 3 figures
   We investigate the crossover from BCS pairing to molecular BEC in an atomic
gas with two fermion species with masses $m_\up \ne m_\dn$ tuned through a
Feshbach resonance. We present results for the T=0 equation of state as a
function of the scattering length including the effects of Gaussian
fluctuations about the mean field ground state. We compute the ground state
energy as a function of $m_\up/m_\dn$ at unitarity and find excellent agreement
with the quantum Monte Carlo result for $m_\up/m_\dn = 6.67$ for a
$^{40}$K-$^6$Li mixture. We show that the dimer scattering length in the BEC
limit as a function of $m_\up/m_\dn$ compares well with exact four-body results
of Petrov {\it et al}. We also derive the condition for trapping frequencies to
obtain an unpolarized gas in a harmonic trap.
\\ ( http://arxiv.org/abs/0906.4300 , 15kb)
Date: Mon, 22 Jun 2009 23:16:11 GMT (355kb)

Title: Dynamics of a bistable Mott insulator to superfluid phase transition in
   cavity optomechanics
Authors: K. Zhang, W. Chen, P. Meystre
Categories: quant-ph
Comments: 6 pages, 5 figures
   We study the dynamics of the many-body state of ultracold bosons trapped in a
bistable optical lattice in an optomechanical resonator controlled by a
time-dependent input field. We focus on the dynamics of the many-body system
following discontinuous jumps of the intracavity field. We identify
experimentally realizable parameters for the bistable quantum phase transition
between Mott insulator and superfluid.
\\ ( http://arxiv.org/abs/0906.4143 , 355kb)
Date: Tue, 23 Jun 2009 03:02:17 GMT (892kb)

Title: Ultracold Fermions in a Graphene-Type Optical Lattice
Authors: Kean Loon Lee, Benoit Gremaud, Rui Han, Berthold-Georg Englert and
   Christian Miniatura
Categories: quant-ph
   Some important features of the graphene physics can be reproduced by loading
ultracold fermionic atoms in a two-dimensional optical lattice with honeycomb
symmetry and we address here its experimental feasibility. We analyze in great
details the optical lattice generated by the coherent superposition of three
coplanar running laser waves with respective angles $2\pi/3$. The corresponding
band structure displays Dirac cones located at the corners of the Brillouin
zone and close to half-filling this system is well described by massless Dirac
fermions. We characterize their properties by accurately deriving the
nearest-neighbor hopping parameter $t_0$ as a function of the optical lattice
parameters. Our semi-classical instanton method proves in excellent agreement
with an exact numerical diagonalization of the full Hamilton operator in the
tight-binding regime. We conclude that the temperature range needed to access
the Dirac fermions regime is within experimental reach. We also analyze
imperfections in the laser configuration as they lead to optical lattice
distortions which affect the Dirac fermions. We show that the Dirac cones do
survive up to some critical intensity or angle mismatches which are easily
controlled in actual experiments. In the tight-binding regime, we predict, and
numerically confirm, that these critical mismatches are inversely proportional
to the square-root of the optical potential strength. We also briefly discuss
the interesting possibility of fine-tuning the mass of the Dirac fermions by
controlling the laser phase in an optical lattice generated by the incoherent
superposition of three coplanar independent standing waves with respective
angles $2\pi/3$.
\\ ( http://arxiv.org/abs/0906.4158 , 892kb)
Date: Tue, 23 Jun 2009 23:45:30 GMT (204kb,D)

Title: A Universal Trimer in a Three-Component Fermi Gas
Authors: A. N. Wenz, T. Lompe, T. B. Ottenstein, F. Serwane, G. Z\"urn, and S.
Categories: cond-mat.quant-gas
Comments: 5 pages, 3 figures
   We show that the recently measured magnetic field dependence of three-body
loss in a three-component mixture of ultracold $^6$Li atoms [1,2] can be
explained by the presence of a universal trimer state. Previous work suggested
a universal trimer state as a probable explanation, yet failed to get good
agreement between theory and experiment over the whole range of magnetic
fields. For our description we adapt the theory of Braaten and Hammer [3] for
three identical bosons to the case of three distinguishable fermions by
combining the three scattering lengths $a_{12},$ $a_{23}$ and $a_{13}$ between
the three components to an effective interaction parameter $a_m$. We show that
taking into account a magnetic field variation of the lifetime of the trimer
state is essential to obtain a complete understanding of the observed decay
\\ ( http://arxiv.org/abs/0906.4378 , 204kb)
Date: Wed, 24 Jun 2009 12:00:52 GMT (63kb)

Title: Feynman path-integral treatment of the BEC-impurity polaron
Authors: J. Tempere, W. Casteels, M.K. Oberthaler, E. Timmermans, J.T. Devreese
Categories: cond-mat.quant-gas
Comments: 13 pages, 3 figures
   The description of an impurity atom in a Bose-Einstein condensate can be cast
in the form of Frohlich's polaron Hamiltonian, where the Bogoliubov excitations
play the role of the phonons. An expression for the corresponding polaronic
coupling strength is derived, relating the coupling strength to the scattering
lengths, the trap size and the number of Bose condensed atoms. This allows to
identify several approaches to reach the strong-coupling limit for the quantum
gas polarons, whereas this limit was hitherto experimentally inaccessible in
solids. We apply Feynman's path-integral method to calculate for all coupling
strengths the polaronic shift in the free energy and the increase in the
effective mass. The effect of temperature on these quantities is included in
the description. We find similarities to the acoustic polaron results and
indications of a transition between free polarons and self-trapped polarons.
The prospects, based on the current theory, of investigating the polaron
physics with ultracold gases are discussed for lithium atoms in a sodium
\\ ( http://arxiv.org/abs/0906.4455 , 63kb)
arXiv:0906.4319 (*cross-listing*)
Date: Tue, 23 Jun 2009 17:20:00 GMT (17kb)

Title: Microscopic description of the chiral Tomonaga-Luttinger liquid at the
   fractional quantum Hall edge
Authors: Wei Huang, Zhao-Long Wang, Mu-Lin Yan
Categories: hep-th cond-mat.mes-hall cond-mat.str-el
Comments: 14 pages, 2 figures
Report-no: USTC-ICTS-09-08
   The effective field theory of the fractional quantum Hall edge is
reformulated from microscopic dynamics. Noncommutative Chern-Simons theory is a
microscopic description for the quantum Hall fluid. We use it for reference.
Considering relabeling symmetry of the electrons and incompressibility of the
fluid, we obtain a constraint and derive a chiral Tomonaga-Luttinger liquid
theory containing interaction terms. We calculate one-loop corrections to the
phonon and electron propagators and get a new tunneling exponent. It agrees
with experiments.
\\ ( http://arxiv.org/abs/0906.4319 , 17kb)
Date: Wed, 24 Jun 2009 07:34:34 GMT (838kb)

Title: Population Dynamics in Cold Gases Resulting from the Long-Range
   Dipole-Dipole Interaction
Authors: A. Mandilara, V. M. Akulin and P. Pillet
Categories: quant-ph
Comments: 6 pages, 8 figures
   We consider the effect of the long range dipole-dipole interaction on the
excitation exchange dynamics of cold two-level atomic gase in the conditions
where the size of the atomic cloud is large as compared to the wavelength of
the dipole transition. We show that this interaction results in population
redistribution across the atomic cloud and in specific spectra of the
spontaneous photons emitted at different angles with respect to the direction
of atomic polarization.
\\ ( http://arxiv.org/abs/0906.4417 , 838kb)
Date: Thu, 25 Jun 2009 05:35:39 GMT (683kb)

Title: Finite temperature theory of bosons in optical lattices
Authors: D. Baillie and P. B. Blakie
Categories: cond-mat.quant-gas
Comments: 24 pages, 21 figures
   A practical finite temperature theory is developed for the superfluid regime
of a weakly interacting Bose gas in an optical lattice with additional harmonic
confinement. We derive an extended Bose-Hubbard model that is valid for shallow
lattices and when excited bands are occupied. Using the
Hartree-Fock-Bogoliubov-Popov mean-field approach, and applying local density
and coarse-grained envelope approximations, we arrive at a theory that can be
numerically implemented accurately and efficiently. We present results for a
three-dimensional system, characterizing the importance of the features of the
extended Bose-Hubbard model and compare against other theoretical results and
show improved agreement with experimental data. We present extensive analysis
of the microscopic parameters in our extended Bose-Hubbard model, exploring the
validity of commonly used approximations.
\\ ( http://arxiv.org/abs/0906.4606 , 683kb)
Date: Thu, 25 Jun 2009 02:33:49 GMT (285kb)

Title: Ground State of Fermions in a ID Trap with $\delta$ Function Interaction
Authors: C. N. Yang
Categories: cond-mat.str-el
Comments: 7 pages, 1 figure
   The ground state of Fermions in a ID trap with $\delta$ function interaction
is studied mathematically with group theory ideas.
\\ ( http://arxiv.org/abs/0906.4593 , 285kb)
Date: Thu, 25 Jun 2009 00:08:13 GMT (222kb)

Title: Phases of a bilayer Fermi gas
Authors: Yusuke Nishida
Categories: cond-mat.quant-gas
Comments: 4 pages, 5 figures
Report-no: MIT-CTP 4048
   We investigate a two-species Fermi gas in which one species is confined in
two parallel layers and interacts with the other species in the
three-dimensional space by a tunable short-range interaction. Based on the
controlled weak coupling analysis and the exact three-body calculation, we show
that the system has a rich phase diagram in the plane of the effective
scattering length and the layer separation. Resulting phases include an
interlayer s-wave pairing, an intralayer p-wave pairing, a dimer Bose-Einstein
condensation, and a Fermi gas of Efimov-like trimers. Our system provides a
widely applicable scheme to induce long-range interlayer correlations in
ultracold atoms.
\\ ( http://arxiv.org/abs/0906.4584 , 222kb)
Date: Thu, 25 Jun 2009 15:01:04 GMT (1152kb)

Title: Spatial Dependence of Entropy in Trapped Ultracold Bose Gases
Authors: Lincoln D. Carr and Markus K. Oberthaler
Categories: cond-mat.quant-gas cond-mat.mes-hall
Comments: 5 pages, 4 figures
   We find a new physical regime in the trapped Bose-Hubbard Hamiltonian using
time-evolving block decimation. Between Mott-insulating and superfluid phases,
the latter induced by trap compression, a spatially self-organized state
appears in which non-local entropy signals entanglement between spatially
distant superfluid shells. We suggest a linear rather than harmonic potential
as an ideal way to observe such a self-organized system. We also explore both
quantum information and thermal entropies in the superfluid regime, finding
that while the former follows the density closely the latter can be strongly
manipulated with the mean field.
\\ ( http://arxiv.org/abs/0906.4708 , 1152kb)
Date: Thu, 25 Jun 2009 16:05:45 GMT (52kb)

Title: Observation of universality in ultracold 7Li three-body recombination
Authors: Noam Gross, Zav Shotan, Servaas Kokkelmans and Lev Khaykovich
Categories: cond-mat.other
Comments: 5 pages, 2 figures
   We report on experimental evidence of universality in ultracold 7Li atoms'
three-body recombination loss in the vicinity of a Feshbach resonance. We
observe a recombination minimum and an Efimov resonance in regions of positive
and negative scattering lengths, respectively, which are connected through the
pole of the Feshbach resonance. Both observed features lie deeply within the
range of validity of the universal theory and we find that the relations
between their properties, i.e. widths and locations, are in an excellent
agreement with the theoretical predictions.
\\ ( http://arxiv.org/abs/0906.4731 , 52kb)
Date: Thu, 25 Jun 2009 16:07:58 GMT (35kb)

Title: Mixtures of correlated bosons and fermions: Dynamical mean-field theory
   for normal and condensed phases
Authors: Krzysztof Byczuk and Dieter Vollhardt
Categories: cond-mat.quant-gas cond-mat.str-el
Comments: 11 pages
   We derive a dynamical mean-field theory for mixtures of interacting bosons
and fermions on a lattice (BF-DMFT). The BF-DMFT is a comprehensive,
thermodynamically consistent framework for the theoretical investigation of
Bose-Fermi mixtures and is applicable for arbitrary values of the coupling
parameters and temperatures. It becomes exact in the limit of high spatial
dimensions $d$ or coordination number $Z$ of the lattice. In particular, the
BF-DMFT treats normal and condensed bosons on equal footing and thus includes
the effects caused by their dynamic coupling. Using the BF-DMFT we investigate
two different interaction models of correlated lattice bosons and fermions, one
where all particles are spinless (model I) and one where fermions carry a spin
one-half (model II). In model I the local, repulsive interaction between bosons
and fermions can give rise to an attractive effective interaction between the
bosons. In model II it can also lead to an attraction between the fermions.
\\ ( http://arxiv.org/abs/0906.4732 , 35kb)
arXiv:0906.4512 (*cross-listing*)
Date: Wed, 24 Jun 2009 16:12:24 GMT (32kb)

Title: Bethe equations for generalized Hubbard models
Authors: V. Fomin, L. Frappat and E. Ragoucy
Categories: hep-th cond-mat.str-el math-ph math.MP
Comments: 36 pages
Report-no: LAPTH-1334/09
   We compute the eigenfunctions, energies and Bethe equations for a class of
generalized integrable Hubbard models based on gl(n|m)\oplus gl(2)
superalgebras. The Bethe equations appear to be similar to the Hubbard model
ones, up to a phase due to the integration of a subset of `simple' Bethe
equations. We discuss relations with AdS/CFT correspondence, and with condensed
matter physics.
\\ ( http://arxiv.org/abs/0906.4512 , 32kb)
Date: Thu, 25 Jun 2009 16:00:22 GMT (1202kb)

Title: Ultra-cold mechanical resonators coupled to atoms in an optical lattice
Authors: Andrew A. Geraci, John Kitching
Categories: quant-ph
Comments: 5 pages, 3 figures
   We propose an experiment utilizing an array of cooled micro-cantilevers
coupled to a sample of ultra-cold atoms trapped near a micro-fabricated
surface. The cantilevers allow individual lattice site addressing for atomic
state control and readout, and potentially may be useful in optical lattice
quantum computation schemes. Assuming resonators can be cooled to their
vibrational ground state, the implementation of a two-qubit controlled-NOT gate
with atomic internal states and the motional states of the resonator is
described. We also consider a protocol for entangling two or more cantilevers
on the atom chip with different resonance frequencies, using the trapped atoms
as an intermediary. Although similar experiments could be carried out with
magnetic microchip traps, the optical confinement scheme we consider may
exhibit reduced near-field magnetic noise and decoherence. Prospects for using
this novel system for tests of quantum mechanics at macroscopic scales or
quantum information processing are discussed.
\\ ( http://arxiv.org/abs/0906.4726 , 1202kb)
Date: Thu, 25 Jun 2009 15:55:52 GMT (221kb)

Title: Measurement and simulation of laser-induced fluorescence from
   non-equilibrium ultracold neutral plasmas
Authors: A. Denning, S. D. Bergeson, and F. Robicheaux
Categories: physics.atom-ph physics.plasm-ph
   We report new measurements and simulations of laser-induced fluorescence in
ultracold neutral plasmas. We focus on the earliest times, when the plasma
equilibrium is evolving and before the plasma expands. In the simulation, the
ions interact via the Yukawa potential in a small cell with wrapped boundary
conditions. We solve the optical Bloch equation for each ion in the simulation
as a function of time. Both the simulation and experiment show the initial
Bloch vector rotation, disorder-induced heating, and coherent oscillation of
the rms ion velocity. Detailed modeling of the fluorescence signal makes it
possible to use fluorescence spectroscopy to probe ion dynamics in ultracold
and strongly coupled plasmas.
\\ ( http://arxiv.org/abs/0906.4724 , 221kb)

The replacements:

replaced with revised version Mon, 22 Jun 2009 10:46:15 GMT (215kb)

Title: Dispersive spectrum and orbital order of spinless p-band fermions in an
   optical lattice
Authors: Xiancong Lu and E. Arrigoni
Categories: cond-mat.str-el
Comments: published version
Journal-ref: Phys. Rev. B 79, 245109 (2009)
\\ ( http://arxiv.org/abs/0902.0388 , 215kb)
arXiv:0902.1069 (*cross-listing*)
replaced with revised version Mon, 22 Jun 2009 10:44:10 GMT (569kb)

Title: Dilute gas of ultracold two-level atoms inside a cavity; generalized
   Dicke model
Authors: Jonas Larson, Maciej Lewenstein
Categories: quant-ph cond-mat.other
Comments: 10 pages, 7 figures
Journal-ref: New J. Phys. 11, 063027 (2009)
\\ ( http://arxiv.org/abs/0902.1069 , 569kb)
replaced with revised version Mon, 22 Jun 2009 14:57:51 GMT (1075kb)

Title: Vortex-Induced Phase Slip Dissipation in a Toroidal Bose-Einstein
   Condensate Flowing Through a Barrier
Authors: F. Piazza, L. A. Collins, and A. Smerzi
Categories: cond-mat.other
Comments: Updated version. A discussion of an analytic criterion for the
   instability of the superfluid is added. The case of vortex anti-vortex
   annihilation is also added to the presented results of the numerical
\\ ( http://arxiv.org/abs/0903.2534 , 1075kb)
replaced with revised version Sat, 20 Jun 2009 01:12:19 GMT (1621kb,D)

Title: Dynamics of Cold Atoms Crossing a One-Way Barrier
Authors: Jeremy J. Thorn, Elizabeth A. Schoene, Tao Li, and Daniel A. Steck
Categories: physics.atom-ph
Comments: 20 pages, 20 figures; update to match published version
Journal-ref: Physical Review A vol. 79, 063402 (2009)
DOI: 10.1103/PhysRevA.79.063402
\\ ( http://arxiv.org/abs/0903.3635 , 1621kb)
replaced with revised version Tue, 23 Jun 2009 10:17:42 GMT (119kb)

Title: Combination of a magnetic Feshbach resonance and an optical
   bound-to-bound transition
Authors: D.M. Bauer, M. Lettner, C. Vo, G. Rempe, S. D\"urr
Categories: cond-mat.other
Journal-ref: Physical Review A 79, 062713 (2009)
DOI: 10.1103/PhysRevA.79.062713
\\ ( http://arxiv.org/abs/0903.3570 , 119kb)
replaced with revised version Tue, 23 Jun 2009 14:16:04 GMT (29kb)

Title: Construction of a Coordinate Bethe Ansatz for the asymmetric simple
   exclusion process with open boundaries
Authors: Damien Simon
Categories: cond-mat.stat-mech math-ph math.MP
Comments: references added, one new subsection and corrected typos
\\ ( http://arxiv.org/abs/0903.4968 , 29kb)
arXiv:0906.0714 (*cross-listing*)
replaced with revised version Tue, 23 Jun 2009 09:58:54 GMT (1901kb)

Title: Towards a random laser with cold atoms
Authors: William Guerin (INLN), Nicolas Mercadier (INLN), Franck Michaud
   (INLN), Davide Brivio (INLN), Luis S. Froufe-P\'erez, R\'emi Carminati (LOA),
   Vitalie Eremeev (LPMMC), Arthur Goetschy (LPMMC), Sergey E. Skipetrov
   (LPMMC), Robin Kaiser (INLN)
Categories: physics.atom-ph cond-mat.dis-nn physics.optics
Comments: Submitted to J. Opt. A for the special issue on nanolasers and random
   lasers (to be published early 2010)
\\ ( http://arxiv.org/abs/0906.0714 , 1901kb)
replaced with revised version Tue, 23 Jun 2009 07:17:18 GMT (24kb)

Title: Quantum entanglement of spin-1 bosons with coupled ground states in
   optical lattices
Authors: B. \"Oztop, M. \"O. Oktel, \"O. E. M\"ustecapl\i o\u{g}lu and L. You
Categories: cond-mat.quant-gas quant-ph
Comments: 18 pages, 8 figures. To be published in Journal of Physics B
Journal-ref: Journal of Physics B 42, 145505 (2009)
\\ ( http://arxiv.org/abs/0906.1686 , 24kb)
replaced with revised version Tue, 23 Jun 2009 13:55:12 GMT (31kb,D)

Title: Framed Hilbert space: hanging the quasi-probability pictures of quantum
Authors: Christopher Ferrie, Joseph Emerson
Categories: quant-ph
Comments: 46 pages, 1 table, contains a review of finite dimensional
   quasi-probability functions
Journal-ref: New J. Phys. 11 (2009) 063040
DOI: 10.1088/1367-2630/11/6/063040
\\ ( http://arxiv.org/abs/0903.4843 , 31kb)
replaced with revised version Thu, 25 Jun 2009 05:28:24 GMT (366kb)

Title: Bloch oscillations of Bose-Einstein condensates: Quantum counterpart of
   dynamical instability
Authors: Andrey R. Kolovsky, Hans J\"urgen Korsch, Eva-Maria Graefe
Categories: quant-ph
Comments: 12 pages, 14 figures
\\ ( http://arxiv.org/abs/0901.4719 , 366kb)

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,                  mdavis_at_physics.uq.edu.au
Australia.                           www.physics.uq.edu.au/people/mdavis/
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