Matt's arXiv selection, Monday 12th June 2006.

From: Matthew Davis <>
Date: Mon, 12 Jun 2006 13:37:11 +1000 (EST)

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Abstracts for this week:

Paper: cond-mat/0606041
Date: Thu, 1 Jun 2006 20:05:36 GMT (137kb)

Title: Effective Potential and Thermodynamics for a Coupled Two-Field Bose Gas
Authors: Marcus Benghi Pinto, Rudnei O. Ramos and Frederico F. de Souza Cruz
Comments: 21 pages, 4 eps figures
Subj-class: Other
   We study the thermodynamics of a two-species homogeneous and dilute Bose gas
that is self-interacting and quadratically coupled to each other. We make use
of field theoretical functional integral techniques and evaluate the one-loop
finite temperature effective potential for this system considering the
resummation of the leading order temperature dependent as well as infrared
contributions. The symmetry breaking pattern associated to the model is then
studied by considering different values of self and inter-species couplings. We
pay special attention to the eventual appearance of reentrant phases and/or
shifts in the observed critical temperatures as compared to the monoatomic
(one-field Bose) case.
\\ ( , 137kb)
Paper: cond-mat/0606043
Date: Fri, 2 Jun 2006 17:39:23 GMT (297kb)

Title: Zero Temperature Thermodynamics of Asymmetric Fermi Gases at Unitarity
Authors: Aurel Bulgac and Michael McNeil Forbes
Comments: 4 pages and 3 figures, revtex4
Report-no: NT_at_UW-06-12
Subj-class: Superconductivity
   The equation of state of a dilute two-component asymmetric Fermi gas at
unitarity is subject to strong constraints, which affect the spatial density
profiles in atomic traps. We determine the relation between the structure of
the spatial density profiles and the T=0 equation of state, based on the most
accurate theoretical predictions available. We also show how the equation of
state can be determined from experimental observations. The current constraints
require the existence of non-trivial partially polarized asymmetric phases.
\\ ( , 297kb)
Paper: cond-mat/0606046
Date: Fri, 2 Jun 2006 16:58:10 GMT (363kb)

Title: Magnetically tuned spin dynamics resonance
Authors: J. Kronj\"ager, C. Becker, P. Navez, K. Bongs, K. Sengstock
Subj-class: Other
   We present the experimental observation of a magnetically tuned resonance
phenomenon resulting from spin mixing dynamics of ultracold atomic gases. In
particular we study the magnetic field dependence of spin conversion in F=2
87Rb spinor condensates in the crossover from interaction dominated to
quadratic Zeeman dominated dynamics. We discuss the observed phenomenon in the
framework of spin dynamics as well as matter wave four wave mixing. Furthermore
we show that the validity range of the single mode approximation for spin
dynamics is significantly extended in the regime of high magnetic field.
\\ ( , 363kb)
Paper: cond-mat/0606050
Date: Fri, 2 Jun 2006 05:16:37 GMT (53kb)

Title: Finite temperature Drude weight of an integrable Bose chain
Authors: Michael Bortz
Comments: 11 pages, 2 figures
Subj-class: Statistical Mechanics
   We study the Drude weight $D(T)$ at finite temperatures $T$ of an integrable
bosonic model where the particles interact via nearest-neighbour coupling on a
chain. At low temperatures, $D(T)$ is shown to be universal in the sense that
this region is equivalently described by a Gaussian model. This low-temperature
limit is also relevant for the integrable one-dimensional Bose gas. We then use
the thermodynamic Bethe ansatz to confirm the low-temperature result, to obtain
the high temperature limit of $D(T)$ and to calculate $D(T)$ numerically.
\\ ( , 53kb)
Paper: cond-mat/0606069
Date: Fri, 2 Jun 2006 18:19:26 GMT (70kb)

Title: Three-fermion problems in optical lattices
Authors: T. Luu, A. Schwenk
Comments: 4 pages, 4 figures
Report-no: UCRL-JRNL-221678
Subj-class: Other
   We present exact results for the spectra of three fermionic atoms in a single
well of an optical lattice. For the three lowest hyperfine states of Li6 atoms,
we find a Borromean state across the region of the distinct pairwise Feshbach
resonances. For K40 atoms, nearby Feshbach resonances are known for two of the
pairs, and a bound three-body state develops towards the positive
scattering-length side. In addition, we study the sensitivity of our results to
atomic details. The predicted few-body phenomena can be realized in optical
lattices in the limit of low tunneling.
\\ ( , 70kb)
Paper: cond-mat/0605335
replaced with revised version Fri, 2 Jun 2006 06:58:14 GMT (214kb)

Title: Ultracold polarized Fermi gas at intermediate temperatures
Authors: Jani-Petri Martikainen
Comments: Added few new citations, minor changes elsewhere
Subj-class: Statistical Mechanics
\\ ( , 214kb)
Paper: cond-mat/0606092
Date: Sun, 4 Jun 2006 05:35:58 GMT (658kb)

Title: Dynamical evolution of a doubly-quantized vortex imprinted in a
   Bose-Einstein Condensate
Authors: A. Mu\~{n}oz Mateo and V. Delgado (Univ. La Laguna)
Comments: 5 pages, 4 figures
Subj-class: Other
   The recent experiment by Y. Shin \emph{et al.} [Phys. Rev. Lett. \textbf{93},
160406 (2004)] on the decay of a doubly quantized vortex imprinted in $^{23}%
$Na condensates is analyzed by numerically solving the Gross-Pitaevskii
equation. Our results, which are in very good quantitative agreement with the
experiment, demonstrate that the vortex decay is mainly a consequence of
dynamical instability. Despite apparent contradictions, the local density
approach is consistent with the experimental results. The monotonic increase
observed in the vortex lifetimes is a consequence of the fact that, for large
condensates, the measured lifetimes incorporate the time it takes for the
initial perturbation to reach the central slice. When considered locally, the
splitting occurs approximately at the same time in every condensate, regardless
of its size.
\\ ( , 658kb)
Paper: cond-mat/0606099
Date: Mon, 5 Jun 2006 06:48:38 GMT (415kb)

Title: Spontaneous spin textures in dipolar spinor condensates
Authors: S. Yi and H. Pu
Comments: 4.1 pages, 4 figures
Subj-class: Other
   We have mapped out a detailed phase diagram that shows the ground state
structure of a spin-1 condensate with magnetic dipole-dipole interactions. We
show that the interplay between the dipolar and the spin-exchange interactions
induces a rich variety of quantum phases that exhibit spontaneous magnetic
ordering in the form of intricate spin textures.
\\ ( , 415kb)
Paper: cond-mat/0606117
Date: Mon, 5 Jun 2006 16:45:51 GMT (89kb)

Title: Fermions at unitarity and Haldane Exclusion Statistics
Authors: R.K. Bhaduri, M.V.N. Murthy and M.K. Srivastava
Comments: 4 pages, 1 postscript figure
Subj-class: Other
   We consider a gas of neutral fermionic atoms at ultra-low temperatures, with
the attractive interaction tuned to Feshbach resonance. We calculate the
variation of the chemical potential and the energy per particle as a function
of temperature by assuming the system to be an ideal gas obeying the Haldane-Wu
fractional exclusion statistics. Our results are in good agreement with the
recently published Monte Carlo calculations of two groups. We also present
results for a harmonically trapped gas.
\\ ( , 89kb)
Paper: cond-mat/0601032
replaced with revised version Sat, 3 Jun 2006 20:11:30 GMT (51kb)

Title: Imaging of critical correlations in optical lattices and atomic traps
Authors: Qian Niu, Iacopo Carusotto, and A. B. Kuklov
Comments: 10 revtex pages, 5 figures, replaced with revised more detailed
Subj-class: Other
Journal-ref: Phys. Rev. A 73, 053604 (2006)
\\ ( , 51kb)
Paper: cond-mat/0602319
replaced with revised version Mon, 5 Jun 2006 19:59:42 GMT (99kb)

Title: Searching for a Supersolid in Cold Atom Optical Lattices
Authors: V.W. Scarola, E. Demler, and S. Das Sarma
Comments: 5 pages, 4 figures
Subj-class: Other
Journal-ref: Phys. Rev. A 73, 051601(R) (2006)
\\ ( , 99kb)
Paper: cond-mat/0604063
replaced with revised version Mon, 5 Jun 2006 16:49:44 GMT (14kb)

Title: Disorder contra Mermin-Wagner-Hohenberg Effect: From Classical Spin
   Systems to Ultracold Atomic Gases
Authors: Jan Wehr (University of Arizona), Armand Niederberger (ICFO), Laurent
   Sanchez-Palencia (LCFIO), Maciej Lewenstein (ICFO)
Comments: minor changes
Proxy: ccsd ccsd-00022177
Subj-class: Other
\\ ( , 14kb)
Paper: cond-mat/0604184
replaced with revised version Fri, 2 Jun 2006 22:59:57 GMT (32kb)

Title: Two-species fermion mixtures with population imbalance
Authors: M. Iskin and C. A. R. Sa de Melo
Comments: 4 pages with 4 figures
Subj-class: Superconductivity; Other
\\ ( , 32kb)
Paper: quant-ph/0606033
Date: Mon, 5 Jun 2006 14:14:34 GMT (928kb)

Title: Observation of Strong Coupling between One Atom and a Monolithic
Authors: Takao Aoki, B. Dayan, E. Wilcut, W. P. Bowen, A. S. Parkins, H. J.
   Kimble, T. J. Kippenberg, K. J. Vahala
   Strong coupling is achieved for individual Cesium atoms falling through the
evanescent field of a high-Q toroidal microresonator. From observations of
transit events as a function of atom-cavity detuning, we determine g_0^m/2pi ~
(40 +/- 5) MHz for interactions near the surface of the resonator, where 2g_0^m
is the single-photon Rabi frequency. Strong coupling g_0^m > (gamma,kappa) is
thereby demonstrated for the interaction of single atoms and optical photons in
a monolithic resonator, where (gamma,kappa)/2pi ~ (2.6,18) MHz are the
dissipative rates for atom and cavity field. By advancing beyond the
conventional setting of Fabry-Perot cavities, our work opens a new avenue for
investigations of optical processes with single atoms and photons in
lithographically fabricated microresonators. Applications include the
implementation of quantum networks, scalable quantum logic with photons, and
quantum information processing on atom chips.
\\ ( , 928kb)
Paper: physics/0603107
replaced with revised version Mon, 5 Jun 2006 16:49:38 GMT (540kb)

Title: Bose-Einstein Condensate Driven by a Kicked Rotor in a Finite Box
Authors: K. Henderson, H. Kelkar, T.C. Li, B. Gutierrez-Medina and M.G. Raizen
Comments: 7 pages, 8 figures
Subj-class: Atomic Physics
\\ ( , 540kb)
Paper: cond-mat/0606129
Date: Tue, 6 Jun 2006 01:12:07 GMT (780kb)

Title: Dynamics of rotating Bose-Einstein condensates probed by Bragg
Authors: S. R. Muniz, D. S. Naik, M. Bhattacharya and C. Raman
Comments: 13 pages, 5 figures. Invited paper submitted to a special issue on
   "Nonlinear Waves" of the (Elsevier) journal 'Math. Comput. Simul.', for
   participants in the 4th IMACS International Conference on Nonlinear Evolution
   Equations and Wave Phenomena (2005). Visit our website at for additional information
Subj-class: Other; Mesoscopic Systems and Quantum Hall Effect;
   Gaseous Bose-Einstein condensates (BECs) have become an important test bed
for studying the dynamics of quantized vortices. In this work we use two-photon
Doppler sensitive Bragg scattering to study the rotation of sodium BECs. We
analyze the microscopic flow field and present laboratory measurements of the
coarse-grained velocity profile. Unlike time-of-flight imaging, Bragg
scattering is sensitive to the direction of rotation and therefore to the phase
of the condensate. In addition, we have non-destructively probed the vortex
flow field using a sequence of two Bragg pulses.
\\ ( , 780kb)
Paper: cond-mat/0606151
Date: Tue, 6 Jun 2006 16:12:30 GMT (344kb)

Title: Structure of vortices in rotating Bose-Einstein condensates
Authors: Gentaro Watanabe, S. Andrew Gifford, Gordon Baym, C. J. Pethick
Comments: 9 pages, 9 figures
Report-no: NORDITA-2006-15
Subj-class: Other; Mesoscopic Systems and Quantum Hall Effect
   We calculate the structure of individual vortices in rapidly rotating
Bose-Einstein condensates in a transverse harmonic trap. Making a Wigner-Seitz
approximation for the unit cell of the vortex lattice, we derive the
Gross-Pitaevskii equation for the condensate wave function in each cell of the
lattice, including effects of varying coarse grained density. We calculate the
Abrikosov parameter, the fractional core area, and the energy of individual
\\ ( , 344kb)
Paper: cond-mat/0606155
Date: Tue, 6 Jun 2006 16:56:15 GMT (404kb)

Title: Coherent matter waves emerging from Mott-insulators
Authors: K. Rodriguez, S.R. Manmana, M. Rigol, R.M. Noack and A. Muramatsu
Comments: 19 pages, 11 figures. Submitted to New Journal of Physics
Subj-class: Other
   We study the formation of (quasi-)coherent matter waves emerging from a Mott
insulator for strongly interacting bosons on a one-dimensional lattice. It has
been shown previously that a quasi-condensate emerges at momentum \pi/2a, where
a is the lattice constant, in the limit of infinitely strong repulsion
(hard-core bosons). Here we show that this phenomenon persists for all values
of the repulsive interaction that lead to a Mott insulator at a commensurate
filling. The non-equilibrium dynamics of hard-core bosons is treated exactly by
means of a Jordan-Wigner transformation, and the generic case is studied using
a time-dependent density matrix renormalization group technique. Different
methods for controlling the emerging matter wave are discussed.
\\ ( , 404kb)
Paper: cond-mat/0605350
replaced with revised version Tue, 6 Jun 2006 15:53:22 GMT (220kb)

Title: The Fermi-Hubbard model at unitarity
Authors: Evgeni Burovski, Nikolay Prokof'ev, Boris Svistunov and Matthias
Comments: v2: minor corrections, fig 7 replaced
Subj-class: Superconductivity; Statistical Mechanics
\\ ( , 220kb)
Paper (*cross-listing*): hep-th/0605259
replaced with revised version Tue, 6 Jun 2006 14:47:05 GMT (23kb)

Title: Symmetry Aspects in Nonrelativistic Multi-Scalar Field Models and
   Application to a Coupled Two-Species Dilute Bose Gas
Authors: Rudnei O Ramos and Marcus B Pinto
Comments: 8 pages, 1 eps figure, IOP style. Based on a talk given by R. O.
   Ramos at the QFEXT05 workshop, Barcelona, Spain, September 5-9, 2005. One
   reference was updated
Subj-class: High Energy Physics - Theory; Soft Condensed Matter
Journal-ref: J.Phys. A39 (2006) 6687-6693
\\ ( , 23kb)
Paper: quant-ph/0606037
Date: Mon, 5 Jun 2006 21:49:53 GMT (690kb)

Title: Spinor Dynamics-Driven Formation of a Dual-Beam Atom Laser
Authors: N. Lundblad, R. J. Thompson, D. C. Aveline, L. Maleki
Comments: 4 pages, 4 figures
   We demonstrate a novel dual-beam atom laser formed by outcoupling oppositely
polarized components of an F=1 spinor Bose-Einstein condensate whose Zeeman
sublevel populations have been coherently evolved through spin dynamics. The
condensate is formed through all-optical means using a single-beam running-wave
dipole trap. We create a condensate in the field-insensitive $m_F=0$ state, and
drive coherent spin-mixing evolution through adiabatic compression of the
initially weak trap. Such dual beams, number-correlated through the angular
momentum-conserving reaction $2m_0\leftrightharpoons m_{+1}+m_{-1}$, have been
proposed as tools to explore entanglement and squeezing in Bose-Einstein
condensates, and have potential use in precision phase measurements.
\\ ( , 690kb)
Paper: quant-ph/0606047
Date: Tue, 6 Jun 2006 17:23:03 GMT (63kb)

Title: Preparation of atomic velocities by bound-state to resonance conversion
Authors: F. Delgado, A. Ruschhaupt, J. G. Muga
   A procedure is proposed to control the average and width of the velocity
distribution of ultra-cold atoms. The atoms are set initially in a bound state
of an optical trap formed by an inner red detuned laser and an outer blue
detuned laser. The bound state is later converted into a resonance by a
suitable change of the laser intensities. An optimal time dependence of the
switching process, between the sudden and adiabatic limits, adjusts the final
translational energies to the Lorentzian shape of the resonance state.
\\ ( , 63kb)
Paper: quant-ph/0601202
replaced with revised version Tue, 6 Jun 2006 10:40:56 GMT (369kb)

Title: Probing BEC phase fluctuations with atomic quantum dots
Authors: M. Bruderer, D. Jaksch
Comments: 11 pages, 3 figures
Journal-ref: New J. Phys. 8 87 (2006)
DOI: 10.1088/1367-2630/8/6/087
\\ ( , 369kb)
Paper: cond-mat/0605604
replaced with revised version Wed, 7 Jun 2006 11:29:47 GMT (61kb)

Title: Pi-Josephson Junction and Spontaneous Superflow in Rings from Ultracold
   Fermionic Atomic Gases
Authors: Miodrag L. Kulic
Comments: 6 pages, 3 figures, Introduction and List of References updated
Subj-class: Statistical Mechanics; Strongly Correlated Electrons
\\ ( , 61kb)
Paper: quant-ph/0606062
Date: Wed, 7 Jun 2006 19:29:33 GMT (652kb)

Title: Probing the quantum state of a guided atom laser pulse
Authors: Kevin L. Moore, Subhadeep Gupta, Kater W. Murch, and Dan M.
Comments: 4 pages, 3 figures
   We describe bichromatic superradiant pump-probe spectroscopy as a tomographic
probe of the Wigner function of a dispersing particle beam. We employed this
technique to characterize the quantum state of an ultracold atomic beam,
derived from a Rb-87 Bose-Einstein condensate, as it propagated in a 2.5 mm
diameter circular waveguide. Our measurements place an upper bound on the
longitudinal phase-space area occupied by the 300,000 atom beam of 9(1) $\hbar$
and a lower bound on the coherence length (L > 13 microns). These results are
consistent with full quantum degeneracy after multiple orbits around the
\\ ( , 652kb)
Paper: cond-mat/0606201
Date: Thu, 8 Jun 2006 01:41:48 GMT (200kb)

Title: Quantum limits to bosonic center-of-mass measurements
Authors: Timothy Vaughan, Peter Drummond, Gerd Leuchs
Comments: 6 pages, 2 figures. Submitted to PRA
Subj-class: Other; Mesoscopic Systems and Quantum Hall Effect
   We discuss various subtleties in identifying the mean position
(center-of-mass) of a bosonic cloud in the presence of particle number
fluctuations. We introduce a standard quantum limit for these measurements and
discuss this limit in the context of both photons and ultra-cold atoms. The
difference between the actual mean-position fluctuation and this limit is
evidence for quantum wave-packet spreading. However, this cannot be readily
observed for normal pulses in a linear dispersive medium, due to classical
pulse broadening. For this reason, we study the evolution of photonic and
matter-wave solitons, where this is suppressed. In the photonic case, we show
that this intrinsic quantum diffusion of the mean position can contribute
significantly to uncertainties in soliton pulse arrival times. On the other
hand, we discuss ways in which the relatively long lifetimes of attractive
bosons in matter-wave solitons may be used to demonstrate quantum interference
between massive objects composed of thousands of particles.
\\ ( , 200kb)
Paper: cond-mat/0606213
Date: Thu, 8 Jun 2006 13:32:11 GMT (545kb)

Title: Photonic crystal optical waveguides for on-chip Bose-Einstein
Authors: J. Bravo-Abad, M. Ibanescu, J.D. Joannopoulos, M. Soljacic
Comments: 5 pages, 4 figures
Subj-class: Materials Science
   We propose an on-chip optical waveguide for Bose-Einstein condensates based
on the evanescent light fields created by surface states of a photonic crystal.
It is shown that the modal properties of these surface states can be tailored
to confine the condensate at distances from the chip surface significantly
longer that those that can be reached by using conventional index-contrast
guidance. We numerically demonstrate that by index-guiding the surface states
through two parallel waveguides, the atomic cloud can be confined in a
two-dimensional trap at about 1$\mu$m above the structure using a power of
\\ ( , 545kb)
Paper: cond-mat/0606216
Date: Thu, 8 Jun 2006 14:32:52 GMT (575kb)

Title: The Mott insulator transition in two dimensions
Authors: I. B. Spielman, W. D. Phillips, and J. V. Porto
Subj-class: Other
   Cold atoms confined in periodic potentials are remarkably versatile quantum
systems for implementing simple models prevalent in condensed matter theory. In
the current experiment, we realize the 2D Bose-Hubbard model by loading a
Bose-Einstein condensate into an optical lattice, and we study the resulting
Mott insulating state (a phase of matter in which atoms are localized on
specific lattice sites). We measure momentum distributions which agree
quantitatively with theory (no adjustable parameters). We also study
correlations in atom shot nose and observe a pronounced dependence on the
lattice depth, this dependence indicates geometric effects to first order and
suggests deviations due to higher order corrections.
\\ ( , 575kb)
Paper: quant-ph/0606065
Date: Thu, 8 Jun 2006 03:39:59 GMT (52kb)

Title: Perfect quantum state transfer with spinor bosons on weighted graphs
Authors: David L. Feder
Comments: 4 pages, 2 figures, revtex
   A duality between the properties of many spinor bosons on a regular lattice
and those of a single particle on a weighted graph reveals that a quantum
particle can traverse an infinite hierarchy of networks with perfect
probability in polynomial time, even as the number of nodes increases
exponentially. The one-dimensional `quantum wire' and the hypercube are special
cases in this construction, where the number of spin degrees of freedom is
equal to one and the number of particles, respectively. An implementation of
near-perfect quantum state transfer across a weighted parallelepiped with
ultracold atoms in optical lattices is discussed.
\\ ( , 52kb)
Paper: quant-ph/0606073
Date: Thu, 8 Jun 2006 13:36:30 GMT (458kb)

Title: Ramsey interferometry with oppositely detuned fields
Authors: D. Seidel, J.G. Muga
Comments: 6 pages, 6 figures
   We report a narrowing of the interference pattern obtained in an atomic
Ramsey interferometer if the two separated fields have different frequency and
their phase difference is controlled. The width of the Ramsey fringes depends
inversely on the free flight time of ground state atoms before entering the
first field region in addition to the time between the fields. The effect is
stable also for atomic wavepackets with initial position and momentum
distributions and for realistic mode functions.
\\ ( , 458kb)
Paper: quant-ph/0606076
Date: Thu, 8 Jun 2006 15:09:31 GMT (22kb)

Title: Polarization squeezing by optical Faraday rotation
Authors: Jacob F. Sherson and Klaus Molmer
Comments: 4 pages, 4 figures
   We show that it is possible to generate continuous-wave fields and pulses of
polarization squeezed light by sending classical, linearly polarized laser
light twice through an atomic sample which causes an optical Faraday rotation
of the field polarization. We characterize the performance of the process, and
we show that an appreciable degree of squeezing can be obtained under realistic
physical assumptions.
\\ ( , 22kb)

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
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Received on Mon Jun 12 2006 - 13:37:11 EST

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