Matt's arXiv selection for Monday 16th January 2006 from Matthew Davis on 2006-01-17 (Matt's arXiv selection)

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Tue, 17 Jan 2006 08:44:25 +1000 (EST)

This week is only a day late....

Cheers,
Matt.

------------------------------------------------------------------------------
\\
Paper: cond-mat/0601103
Date: Thu, 5 Jan 2006 21:49:02 GMT (110kb)

Title: Pomeranchuk and Topological Fermi Surface Instabilities from Central
Interactions
Authors: J. Quintanilla and A. J. Schofield
Comments: 6 pages, 3 figures
Subj-class: Strongly Correlated Electrons; Statistical Mechanics
\\
We address, at the mean field (MF) level, the emergence of a Pomeranchuk
instability (PI) in a uniform Fermi liquid with \emph{central}
particle-particle interactions. We find that a PI with all symmetries, except
$l=1,$ can take place if the interaction is repulsive and has a finite range
$r_{0}$ of the order of the inter-particle distance. We demonstrate this by
solving the MF equations analytically for a simple model interaction. We find,
in addition to the PI, other, subtler phase transitions in which the Fermi
surface changes topology without rotational symmetry-breaking. We argue that
such ``interaction-driven Lifshitz transitions'' may be as generic to such
systems as the PI.
\\ ( http://arXiv.org/abs/cond-mat/0601103 , 110kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0601109
Date: Fri, 6 Jan 2006 18:50:58 GMT (26kb)

Title: Path Integral Monte Carlo Applied to Nearly Parallel Vortex Filaments
Authors: Timothy Andersen and Chjan Lim
Comments: 17 pages, 5 figures
Subj-class: Statistical Mechanics; Superconductivity
\\
The Nearly Parallel Vortex Filament (NPVF) model has a wide range of
applications from classical fluid turbulence to electron plasmas to superfluids
and Bose-Einstein Condensates. Ceperley's Path Integral Monte Carlo (PIMC)
algorithms provide an excellent tool for calculating the statistics of these
systems in equilibrium, as Sen, Trivedi and Ceperley showed for flux lines of
type-II superconductors by \cite{Sen:2001}. In this poster we discuss our
application of PIMC to NPVF to study the melting of vortex crystals under a
trapping potential when trapping intensity (e.g. angular velocity) increases,
forcing higher vortex densities. We discover a phase transition in which
control of the statistics of containment radius transfers from vortex
interaction in the crystal phase to internal vortex fluctuations in the liquid
phase. At the critical point entropy rather than internal energy becomes the
main factor deciding the system state, consequently the radius becomes chaotic.
We also show that this transition does not exist in the point vortex model.
This work represents the first numerical evidence for the kind of turbulence
occuring at high rotation speed due to vortex tangling. We argue that the
simplified, NPVF model is sufficient to make these assertions and that the full
Biot-Savart law is unnecessary.
\\ ( http://arXiv.org/abs/cond-mat/0601109 , 26kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0601113
Date: Fri, 6 Jan 2006 07:56:34 GMT (17kb)

Title: Inhomogeneous Hubbard Models: from Weak to Strong Coupling
Authors: Wei-Feng Tsai and Steven A. Kivelson
Comments: 4 pages, 3 figures
Subj-class: Strongly Correlated Electrons; Superconductivity
\\
We present a controlled perturbative approach to the low temperature phase
diagram of highly inhomogeneous Hubbard models in the limit of small coupling,
$t'$, between clusters. We apply this to the dimerized and checkerboard models.
The dimerized model is found to behave like a doped semiconductor, with a
Fermi-liquid groundstate with parameters ({\it e.g.} the effective mass) which
are smooth functions of the Hubbard interaction, $U$. By contrast, the
checkerboard model has a Fermi liquid phase at large $U > U_c = 4.67$, a d-wave
superconducting state with a full gap for $U_c > U > 0$, and a narrow strip of
an intermediate d-wave superconducting phase with gapless ``nodal''
quasiparticles for $|U - U_c| < {\cal O}(t^\prime)$.
\\ ( http://arXiv.org/abs/cond-mat/0601113 , 17kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0601122
Date: Fri, 6 Jan 2006 15:26:59 GMT (38kb)

Title: Density profile of a polarized unitary Fermi gas
Authors: Fr\'{e}d\'{e}ric Chevy (LKB - Lhomond)
Comments: 4 pages, 3 figures
Proxy: ccsd ccsd-00016604
Subj-class: Statistical Mechanics
\\
We present a theoretical study of the density profile of a trapped strongly
interacting Fermi gas with unbalanced spin populations. Making the assumption
of the existence of a first order phase transition between an unpolarized
superfluid phase and a fully polarized normal phase, we show good agreement
with a recent experiment presented in Partridge et al.
\\ ( http://arXiv.org/abs/cond-mat/0601122 , 38kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0601125
Date: Fri, 6 Jan 2006 17:39:06 GMT (50kb)

Title: On the free energy within the mean-field approximation
Authors: R. Agra, F. van Wijland, E. Trizac
Comments: pedagogical paper for undergraduate teaching, to appear in Eur. J.
Physics
Subj-class: Statistical Mechanics; Materials Science
\\
We compare two widespread formulations of the mean-field approximation, based
on minimizing an appropriately built mean-field free energy. We use the example
of the antiferromagnetic Ising model to show that one of these formulations
does not guarantee the existence of an underlying variational principle. This
results in a severe failure where straightforward minimization of the
corresponding mean-field free energy leads to incorrect results.
\\ ( http://arXiv.org/abs/cond-mat/0601125 , 50kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0508645
replaced with revised version Thu, 5 Jan 2006 21:00:48 GMT (31kb)

Title: Potential-energy (BCS) to kinetic-energy (BEC)-driven pairing in the
attractive Hubbard model
Authors: B. Kyung, A. Georges, and A. -M. S. Tremblay
Comments: 4.1 pages, 4 figures
Subj-class: Strongly Correlated Electrons; Superconductivity
\\ ( http://arXiv.org/abs/cond-mat/0508645 , 31kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0511332
replaced with revised version Fri, 6 Jan 2006 14:21:24 GMT (26kb)

Title: Ground state energy of spin-1/2 fermions in the unitary limit
Authors: Dean Lee (North Carolina State University)
Comments: 17 pages, 9 figures, expanded manuscript includes more data and
cross-checks
Subj-class: Statistical Mechanics
\\ ( http://arXiv.org/abs/cond-mat/0511332 , 26kb)
------------------------------------------------------------------------------
\\
Paper: physics/0601036
Date: Fri, 6 Jan 2006 16:23:26 GMT (603kb)

Title: Coherent manipulation of atoms by co-propagating laser beams
Authors: Yuri B. Ovchinnikov
Comments: 19 pages, 12 figures
Subj-class: Atomic Physics
\\
Optical dipole traps and fractional Talbot optical lattices based on the
interference between multiple co-propagating laser beams are proposed. The
variation of relative amplitudes and phases of the interfering light beams of
these traps makes it possible to manipulate the spatial position of trapped
atoms. Examples of spatial translation and splitting of atoms between a set of
the interference traps are considered. The prospect of constructing all-light
atom chips based on the proposed technique is presented.
\\ ( http://arXiv.org/abs/physics/0601036 , 603kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0601140
Date: Mon, 9 Jan 2006 19:15:59 GMT (7kb)

Title: Relaxation of the molecular state in atomic Fermi gases near a Feshbach
resonance
Authors: V. S. Babichenko
Comments: RevTex4, 4 pages
Subj-class: Other
\\
Relaxation processes in ultra-cold degenerate atomic Fermi gas near a
Feshbach resonance are considered. It is shown that the relaxation rate of the
molecules being in a resonance with the atomic Fermi system is of the order of
the part of the chemical potential defined by the interaction between resonance
molecules. In this connection the lower part of the excitation spectrum of the
system of resonance molecules is not defined well.
\\ ( http://arXiv.org/abs/cond-mat/0601140 , 7kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0601147
Date: Sun, 8 Jan 2006 16:02:10 GMT (520kb)

Title: LOFF Pairing vs. Breached Pairing in Asymmetric Fermion Superfluids
Authors: Lianyi He, Meng Jin and Pengfei Zhuang
Comments: 14 pages, 18 figures
Subj-class: Superconductivity
\\
A general analysis for the competition between breached pairing and LOFF
pairing mechanisms in asymmetric fermion superfluids is presented in the frame
of a four fermion interaction model in weak coupling region. For the
superfluids with mismatched Fermi surfaces formed in different physical
systems, we analytically and numerically calculated the coupled set of
equations for the gap parameter, pair momentum, and thermodynamic potential.
The breached pairing state is instable due to the Sarma instability or magnetic
instability in any asymmetric system. While the LOFF state is stable only in a
narrow asymmetry window in the case with fixed chemical potentials or fixed
total number and chemical potential difference, it is stable in the whole
coexistence region of breached pairing and LOFF pairing states in the case with
fixed numbers of the two species. The LOFF state can even survive in the highly
asymmetry region where the breached pairing state disappears.
\\ ( http://arXiv.org/abs/cond-mat/0601147 , 520kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0601148
Date: Sun, 8 Jan 2006 16:25:32 GMT (75kb)

Title: Finite Size Effects in Cold Asymmetrical Fermion Superfluids
Authors: Heron Caldas
Comments: 5 pages, 3 figures (eps)
Subj-class: Superconductivity
\\
We derive the surface energy between the normal and superfluid components of
a mixed phase of a system composed of two particle species with different
densities. The surface energy is obtained by the integration of the free energy
density in the interface between the two phases. We show that the mixed phase
remains as the favored ground state over the gapless phase, even upon the
consideration of the surface energy.
\\ ( http://arXiv.org/abs/cond-mat/0601148 , 75kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0601151
Date: Sun, 8 Jan 2006 21:18:42 GMT (404kb)

Title: Resonant control of spin dynamics in ultracold quantum gases by
   microwave dressing
Authors: Fabrice Gerbier, Artur Widera, Simon Foelling, Olaf Mandel, Immanuel
   Bloch
Comments: 4 pages, 5 figures
Subj-class: Other
\\
   We study experimentally interaction-driven spin oscillations in optical
lattices in the presence of an off-resonant microwave field. We show that the
energy shift induced by this microwave field can be used to control the spin
oscillations by tuning the system either into resonance to achieve near-unity
contrast or far away from resonance to suppress the oscillations. Finally, we
propose a scheme based on this technique to create a flat sample with either
singly- or doubly-occupied sites, starting from an inhomogeneous Mott
insulator, where singly- and doubly-occupied sites coexist.
\\ ( http://arXiv.org/abs/cond-mat/0601151 , 404kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0506472
replaced with revised version Sat, 7 Jan 2006 13:17:29 GMT (710kb)

Title: Dynamical stabilization of matter-wave solitons revisited
Authors: Alexander Itin, Shinichi Watanabe, Toru Morishita
Subj-class: Other; Atomic Physics; Chaotic Dynamics
\\ ( http://arXiv.org/abs/cond-mat/0506472 , 710kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0508063
replaced with revised version Mon, 9 Jan 2006 20:28:10 GMT (33kb)

Title: Bosonization, Pairing, and Superconductivity of the Fermionic
   Tonks-Girardeau Gas
Authors: M.D. Girardeau and A. Minguzzi
Comments: v3: 4 pages, 2 figures, revtex4. Section on the fermionic TG gas on a
   ring revised, emphasizing degeneracy of ground state for even N and resultant
   high sensitivity to external fields. Submitted to PRL
Subj-class: Superconductivity
\\ ( http://arXiv.org/abs/cond-mat/0508063 , 33kb)
------------------------------------------------------------------------------
\\
Paper: quant-ph/0601049
Date: Mon, 9 Jan 2006 10:41:54 GMT (89kb)

Title: Atomic reflection off conductor walls as a tool in cold atom traps
Authors: M. Al-Amri and M. Babiker
Comments: article
\\
We explain why a system of cold $^{85}Rb$ atoms at temperatures of the order
$T\approx 7.78\times 10^{-5}$ K and below, but not too low to lie in the
quantum reflection regime, should be automatically repelled from the surface of
a conductor without the need of an evanescent field, as in a typical atom
mirror, to counteract the van der Waals attraction. The repulsive potential
arises naturally outside the conductor and is effective at distances from the
conductor surface of about 400nm, intermediate between the van der Waals and
the Casimir-Polder regions of variation. We propose that such a field-free
reflection capability should be useful as a component in cold atom traps. It
should be practically free of undesirable field fluctuations and would be
operative at distances for which surface roughness, dissipative effects and
other finite conductivity effects should be negligibly small.
\\ ( http://arXiv.org/abs/quant-ph/0601049 , 89kb)
------------------------------------------------------------------------------
\\
Paper: quant-ph/0601052
Date: Mon, 9 Jan 2006 19:14:09 GMT (528kb)

Title: Ion Trap in a Semiconductor Chip
Authors: D. Stick, W. K. Hensinger, S. Olmschenk, M. J. Madsen, K. Schwab, and
C. Monroe
Comments: 4 pages, 4 figures
Journal-ref: Nature Phys. 2 (2006) 36-39
\\
The electromagnetic manipulation of isolated atoms has led to many advances
in physics, from laser cooling and Bose-Einstein condensation of cold gases to
the precise quantum control of individual atomic ion. Work on miniaturizing
electromagnetic traps to the micrometer scale promises even higher levels of
control and reliability. Compared with 'chip traps' for confining neutral
atoms, ion traps with similar dimensions and power dissipation offer much
higher confinement forces and allow unparalleled control at the single-atom
level. Moreover, ion microtraps are of great interest in the development of
miniature mass spectrometer arrays, compact atomic clocks, and most notably,
large scale quantum information processors. Here we report the operation of a
micrometer-scale ion trap, fabricated on a monolithic chip using semiconductor
micro-electromechanical systems (MEMS) technology. We confine, laser cool, and
measure heating of a single 111Cd+ ion in an integrated radiofrequency trap
etched from a doped gallium arsenide (GaAs) heterostructure.
\\ ( http://arXiv.org/abs/quant-ph/0601052 , 528kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0601184
Date: Tue, 10 Jan 2006 02:24:38 GMT (739kb)

Title: Observation of Strong Quantum Depletion in a Gaseous Bose-Einstein
Condensate
Authors: K. Xu, Y. Liu, D.E. Miller, J.K. Chin, W. Setiawan and W. Ketterle
Subj-class: Other
\\
We studied quantum depletion in a gaseous Bose-Einstein condensate. An
optical lattice enhanced the atomic interactions and modified the dispersion
relation resulting in strong quantum depletion. The depleted fraction was
directly observed as a diffuse background in the time-of-flight images.
Bogoliubov theory provided a semi-quantitative description for our observations
of depleted fractions in excess of 50%.
\\ ( http://arXiv.org/abs/cond-mat/0601184 , 739kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0601195
Date: Tue, 10 Jan 2006 12:11:14 GMT (910kb)

Title: Applications of density matrices in a trapped Bose gas
Authors: K. Ch. Chatzisavvas, S. E. Massen, Ch. C. Moustakidis, C. P. Panos
Comments: 40 pages, 14 figures, 2 Tables
Subj-class: Other
\\
An overview of the Bose-Einstein condensation of correlated atoms in a trap
is presented by examining the effect of interparticle correlations to one- and
two-body properties of the above systems at zero temperature in the framework
of the lowest order cluster expansion. Analytical expressions for the one- and
two-body properties of the Bose gas are derived using Jastrow-type correlation
function. In addition numerical calculations of the natural orbitals and
natural occupation numbers are also carried out. Special effort is devoted for
the calculation of various quantum information properties including Shannon
entropy, Onicescu informational energy, Kullback-Leibler relative entropy and
the recently proposed Jensen-Shannon divergence entropy. The above quantities
are calculated for the trapped Bose gases by comparing the correlated and
uncorrelated cases as a function of the strength of the short-range
correlations. The Gross-Piatevskii equation is solved giving the density
distributions in position and momentum space, which are employed to calculate
quantum information properties of the Bose gas.
\\ ( http://arXiv.org/abs/cond-mat/0601195 , 910kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0508624
replaced with revised version Tue, 10 Jan 2006 02:49:26 GMT (212kb)

Title: Kolmogorov Spectrum of Quantum Turbulence
Authors: Michikazu Kobayashi and Makoto Tsubota
Comments: 14pages, 24 figures and 1 table. Appeared in Journal of the Physical
Society of Japan, Vol.74, No.12, p.3248-3258
Subj-class: Other; Statistical Mechanics
Journal-ref: J. Phys. Soc. Jpn 74, 3248 (2005)
\\ ( http://arXiv.org/abs/cond-mat/0508624 , 212kb)
------------------------------------------------------------------------------
\\
Paper: quant-ph/0601063
Date: Tue, 10 Jan 2006 17:40:17 GMT (13kb)

Title: Dynamics of Open Bosonic Quantum Systems in Coherent State
Representation
Authors: D.A.R. Dalvit, G.P. Berman, and M. Vishik
Comments: 7 pages
Journal-ref: Phys. Rev. A 73, 013803 (2006)
\\
We consider the problem of decoherence and relaxation of open bosonic quantum
systems from a perspective alternative to the standard master equation or
quantum trajectories approaches. Our method is based on the dynamics of
expectation values of observables evaluated in a coherent state representation.
We examine a model of a quantum nonlinear oscillator with a density-density
interaction with a collection of environmental oscillators at finite
temperature. We derive the exact solution for dynamics of observables and
demonstrate a consistent perturbation approach.
\\ ( http://arXiv.org/abs/quant-ph/0601063 , 13kb)
------------------------------------------------------------------------------
\\
Paper: physics/0601054
Date: Mon, 9 Jan 2006 23:01:40 GMT (806kb)

Title: Cold Molecule Spectroscopy for Constraining the Evolution of the Fine
Structure Constant
Authors: Eric R. Hudson, H. J. Lewandowski, Brian C. Sawyer, Jun Ye
Subj-class: Atomic Physics; General Physics
\\
We report precise measurements of ground-state, $\lambda$-doublet microwave
transitions in the hydroxyl radical molecule (OH). Utilizing slow, cold
molecules produced by a Stark decelerator we have improved over the precision
of the previous best measurement by twenty-five-fold for the F' = 2 $\to$ F = 2
transition, yielding (1 667 358 996 $\pm$ 4) Hz, and by ten-fold for the F' = 1
$\to$ F = 1 transition, yielding (1 665 401 803 $\pm$ 12) Hz. Comparing these
laboratory frequencies to those from OH megamasers in interstellar space will
allow a sensitivity of 1 ppm for $\Delta\alpha/\alpha$ over $\sim$$10^{10}$
years.
\\ ( http://arXiv.org/abs/physics/0601054 , 806kb)
------------------------------------------------------------------------------

\\
Paper: cond-mat/0601217
Date: Wed, 11 Jan 2006 07:23:32 GMT (878kb)

Title: Two-dimensional solitons in the Gross-Pitaevskii equation with spatially
modulated nonlinearity
Authors: Hidetsugu Sakaguchi and Boris A. Malomed
Comments: 11 pages, 9 figures
Subj-class: Superconductivity; Statistical Mechanics
\\
We introduce a dynamical model of a Bose-Einstein condensate based on the 2D
Gross-Pitaevskii equation, in which the nonlinear coefficient is a function of
radius. The model describes a situation with spatial modulation of the negative
atomic scattering length, via the Feshbach resonance controlled by a properly
shaped magnetic of optical field. We focus on the configuration with the
nonlinear coefficient different from zero in a circle or annulus, including the
case of a narrow ring. Two-dimensional axisymmetric solitons are found in a
numerical form, and also by means of a variational approximation; for an
infinitely narrow ring, the soliton is found in an exact form (in the latter
case, exact solitons are also found in a two-component model). A stability
region for the solitons is identified by means of numerical and analytical
methods. In particular, if the nonlinearity is supported on the annulus, the
upper stability border is determined by azimuthal perturbations; the stability
region disappears if the ratio of the inner and outer radii of the annulus
exceeds a critical value 0.47. The model gives rise to bistability, as the
stationary solitons coexist with stable axisymmetric breathers, whose stability
region extends to higher values of the norm than that of the static solitons.
The collapse threshold strongly increases with the radius of the inner hole of
the annulus. Vortex solitons are found too, but they are unstable.
\\ ( http://arXiv.org/abs/cond-mat/0601217 , 878kb)
------------------------------------------------------------------------------

\\
Paper: cond-mat/0601228
Date: Wed, 11 Jan 2006 13:45:46 GMT (38kb)

Title: Small polarons in dilute gas Bose-Einstein condensates
Authors: Fernando M. Cucchietti and Eddy Timmermans
Report-no: LA-UR-06-0083
Subj-class: Other
\\
A neutral impurity atom immersed in a dilute Bose-Einstein condensate (BEC)
can have a bound ground state in which the impurity is self-localized. In this
small polaron-like state, the impurity distorts the density of the surrounding
BEC, thereby creating the self-trapping potential minimum. We describe the
self-localization in a strong coupling approach.
\\ ( http://arXiv.org/abs/cond-mat/0601228 , 38kb)
------------------------------------------------------------------------------
\\
Paper: physics/0601073
Date: Wed, 11 Jan 2006 11:55:33 GMT (70kb)

Title: Properties of quasi-one-dimensional molecules with Feshbach resonance
interaction
Authors: V. A. Yurovsky (Tel Aviv University)
Comments: 7 pages, 5 figures
Subj-class: Atomic Physics
\\
Bound states and collisions of atoms with two-channel two-body interactions
in harmonic waveguides are analyzed. The closed-channel contributions to
two-atom bound states become dominant in a case of a weak resonance. At low
energies and values of the non-resonant scattering length the problem can be
approximated by a one-dimensional resonant model. Three-body problem becomes
nonintegrable and properties of three-atomic molecules become different from
ones in the integrable Lieb-Liniger-McGuire model.
\\ ( http://arXiv.org/abs/physics/0601073 , 70kb)
------------------------------------------------------------------------------

\\
Paper: cond-mat/0601249
Date: Thu, 12 Jan 2006 09:36:24 GMT (387kb)

Title: Self-trapping of Bose-Einstein condensates in optical lattices
Authors: Bingbing Wang, Panming Fu, Jie Liu, and Biao Wu
Comments: 8 pages, 15 figures
Subj-class: Other
\\
The self-trapping phenomenon of Bose-Einstein condensates (BECs) in optical
lattices is studied extensively by numerically solving the Gross-Pitaevskii
equation. Our numerical results not only reproduce the phenomenon that was
observed in a recent experiment [Anker {\it et al.}, Phys. Rev. Lett. {\bf 94}
(2005)020403], but also find that the self-trapping breaks down at long
evolution times, that is, the self-trapping in optical lattices is only
temporary. The analysis of our numerical results shows that the self-trapping
in optical lattices is related to the self-trapping of BECs in a double-well
potential. A possible mechanism of the formation of steep edges in the wave
packet evolution is explored in terms of the dynamics of relative phases
between neighboring wells.
\\ ( http://arXiv.org/abs/cond-mat/0601249 , 387kb)
------------------------------------------------------------------------------
\\
Paper: cond-mat/0601269
Date: Thu, 12 Jan 2006 17:34:28 GMT (78kb)

Title: Phase transitions in the boson-fermion resonance model in one dimension
Authors: Edmond Orignac (ENS-Lyon), Roberta Citro (Salerno)
Comments: 31 pages, 8 EPS figures, RevTeX 4, long version of cond-mat/0505706
Subj-class: Mesoscopic Systems and Quantum Hall Effect; Other
\\
We study 1D fermions with photoassociation or with a narrow Fano-Feshbach
resonance described by the Boson-Fermion resonance model. Using thebosonization
technique, we derive a low-energy Hamiltonian of the system. We show that at
low energy, the order parameters for the Bose Condensation and fermion
superfluidity become identical, while a spin gap and a gap against the
formation of phase slips are formed. As a result of these gaps, charge density
wave correlations decay exponentially in contrast with the phases where only
bosons or only fermions are present. We find a Luther-Emery point where the
phase slips and the spin excitations can be described in terms of
pseudofermions. This allows us to provide closed form expressions of the
density-density correlations and the spectral functions. The spectral functions
of the fermions are gapped, whereas the spectral functions of the bosons remain
gapless. The application of a magnetic field results in a loss of coherence
between the bosons and the fermion and the disappearance of the gap. Changing
the detuning has no effect on the gap until either the fermion or the boson
density is reduced to zero. Finally, we discuss the formation of a Mott
insulating state in a periodic potential. The relevance of our results for
experiments with ultracold atomic gases subject to one-dimensional confinement
is also discussed.
\\ ( http://arXiv.org/abs/cond-mat/0601269 , 78kb)
------------------------------------------------------------------------------
\\
Paper: quant-ph/0601079
Date: Thu, 12 Jan 2006 09:03:30 GMT (167kb)

Title: Entanglement of indistinguishable particles in condensed matter physics
Authors: Mark R. Dowling, Andrew C. Doherty and Howard M. Wiseman
Comments: 13 pages, 6 figures, comments welcome
\\
The concept of entanglement in systems where the particles are
indistinguishable has been the subject of much recent interest and controversy.
In this paper we study the notion of entanglement of particles introduced by
Wiseman and Vaccaro [Phys. Rev. Lett. 91, 097902 (2003)] in several specific
physical systems, including some that occur in condensed matter physics. The
entanglement of particles is relevant when the identical particles are
itinerant and so not distinguished by their position as in spin models. We show
that entanglement of particles can behave differently to other approaches that
have been used previously, such as entanglement of modes (occupation-number
entanglement) and the entanglement in the two-spin reduced density matrix. We
argue that the entanglement of particles is what could actually be measured in
most experimental scenarios and thus its physical significance is clear. This
suggests entanglement of particles may be useful in connecting theoretical and
experimental studies of entanglement in strongly-correlated condensed matter
systems.
\\ ( http://arXiv.org/abs/quant-ph/0601079 , 167kb)
------------------------------------------------------------------------------
\\
Paper: quant-ph/0601079
Date: Thu, 12 Jan 2006 09:03:30 GMT (167kb)

Title: Simulating the t-J-U Hamiltonian with atoms in optical lattices
Authors: Alexander Klein and Dieter Jaksch
Comments: 8 pages, 4 figures
\\
We show how the t-J-U Hamiltonian, which is often discussed in the field of
high-temperature superconductivity, can be simulated using ultracold atoms in
optical lattices. For this purpose, previous simulation schemes are extended to
overcome the restriction of a filling factor of exactly one. The time needed to
simulate the Hamiltonian is estimated and the accuracy of the simulation
process is investigated numerically for small systems.
\\ ( http://arXiv.org/abs/quant-ph/0601083 , 177kb)
------------------------------------------------------------------------------
Received on Tue Jan 17 2006 - 08:44:25 EST

This archive was generated by hypermail 2.2.0 : Thu May 08 2008 - 11:51:41 EST