From: Matthew Davis <mdavis_at_physics.uq.edu.au>

Date: Tue, 24 Jun 2008 20:30:16 +1000

Date: Tue, 24 Jun 2008 20:30:16 +1000

The following message was sent to the matts_arxiv list by Matthew Davis <mdavis_at_physics.uq.edu.au>

Hello again,

This week had 31 new preprints and 9 replacements.

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arXiv:0805.4684

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

Title: Ground-state properties of fermionic mixtures with mass imbalance in

optical lattices

Authors: Pavol Farkasovsky

Categories: cond-mat.str-el

Comments: 10 pages, 5 figures

\\

Ground-state properties of fermionic mixtures confined in a one-dimensional

optical lattice are studied numerically within the spinless Falicov-Kimball

model with a harmonic trap. A number of remarkable results are found. (i) At

low particle filling the system exhibits the phase separation with heavy atoms

in the center of the trap and light atoms in the surrounding regions. (ii)

Mott-insulating phases always coexist with metallic phases. (iii)

Atomic-density waves are observed in the insulating regions for all particle

fillings near half-filled lattice case. (iv) The variance of the local density

exhibits the universal behavior (independent of the particle filling, the

Coulomb interaction and the strength of a confining potential) over the whole

region of the local density values.

\\ ( http://arxiv.org/abs/0805.4684 , 63kb)

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arXiv:0805.4743

Date: Fri, 30 May 2008 14:42:42 GMT (351kb)

Title: Collective excitations in one-dimensional ultracold Fermi gases: a

comparative study

Authors: Wei Li, Gao Xianlong, Corinna Kollath, Marco Polini

Categories: cond-mat.str-el

Comments: 11 pages, 6 figures, submitted

\\

Time-dependent density-functional theory (TDDFT) is a powerful tool to study

the non-equilibrium dynamics of inhomogeneous interacting many-body systems.

Here we show that the simple adiabatic local-spin-density approximation for the

time-dependent exchange-correlation potential is surprisingly accurate in

describing collective density and spin dynamics in strongly correlated

one-dimensional ultracold Fermi gases. Our conclusions are based on extensive

comparisons between our TDDFT results and accurate results based on the

adaptive time-dependent density-matrix renormalization-group method.

\\ ( http://arxiv.org/abs/0805.4743 , 351kb)

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arXiv:0805.4681

Date: Fri, 30 May 2008 07:08:56 GMT (156kb)

Title: Stability of Fock states in a two-component Bose-Einstein condensate

with a regular classical counterpart

Authors: Wen-ge Wang, Jie Liu, and Baowen Li

Categories: quant-ph

Comments: 8 pages and 8 figures

\\

We study the stability of a two-component Bose-Einstein condensate (BEC) in

the parameter regime in which its classical counterpart has regular motion. The

stability is characterized by the fidelity for both the same and different

initial states. We study as initial states the Fock states with definite

numbers of atoms in each component of the BEC. It is found that for some

initial times the two Fock states with all the atoms in the same component of

the BEC are stabler than Fock states with atoms distributed in the two

components. An experimental scheme is discussed, in which the fidelity can be

measured in a direct way.

\\ ( http://arxiv.org/abs/0805.4681 , 156kb)

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arXiv:0805.4794

Date: Fri, 30 May 2008 15:37:21 GMT (112kb)

Title: Structure of quantum correlations in momentum space and off diagonal

long range order in eta pairing and BCS states

Authors: Paolo Giorda and Alberto Anfossi

Categories: quant-ph

Comments: 11 pages, 3 figures

\\

The quantum states built with the eta paring mechanism i.e., eta pairing

states, were first introduced in the context of high temperature

superconductivity where they were recognized as important example of states

allowing for off-diagonal long-range order (ODLRO). In this paper we describe

the structure of the correlations present in these states when considered in

their momentum representation and we explore the relations between the quantum

bipartite/multipartite correlations exhibited in k space and the direct lattice

superconducting correlations. In particular, we show how the negativity between

paired momentum modes is directly related to the ODLRO. Moreover, we

investigate the dependence of the block entanglement on the choice of the modes

forming the block and on the ODLRO; consequently we determine the multipartite

content of the entanglement through the evaluation of the generalized "Meyer

Wallach" measure in the direct and reciprocal lattice. The determination of the

persistency of entanglement shows how the network of correlations depicted

exhibits a self-similar structure which is robust with respect to "local"

measurements. Finally, we recognize how a relation between the momentum-space

quantum correlations and the ODLRO can be established even in the case of BCS

states.

\\ ( http://arxiv.org/abs/0805.4794 , 112kb)

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arXiv:0806.0039

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

Title: Ground state of low dimensional dipolar gases: linear, zigzag and

multiple chains

Authors: G. E. Astrakharchik, Giovanna Morigi, Gabriele De Chiara, and J.

Boronat

Categories: cond-mat.other

\\

We study the ground state properties of ultracold dipolar gases in highly

anisotropic traps. Starting from a one-dimensional geometry, by ramping down

the transverse confinement along one direction, the gas reaches various planar

distributions of dipoles. At large linear densities, when the dipolar gas

exhibits a crystal-like phase, one can identify critical values of the

transverse frequency at which the configuration starts exhibiting novel

transverse spatial correlations. These critical values can be identified by

means of a classical theory, and are in full agreement with classical Monte

Carlo simulations. The numerical study of the quantum system is performed by

using diffusion Monte Carlo technique and shows that the quantum fluctuations

smoothen the transition and make it completely disappear in a gas phase.

\\ ( http://arxiv.org/abs/0806.0039 , 163kb)

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arXiv:0806.0166

Date: Mon, 2 Jun 2008 19:15:45 GMT (642kb,D)

Title: Preparation and detection of d-wave superfluidity in two-dimensional

optical superlattices

Authors: A. M. Rey, R. Sensarma, S. Foelling, M. Greiner, E. Demler and M.D.

Lukin

Categories: cond-mat.other

Comments: 8 pages, 6 figures

\\

We propose a controlled method to create and detect d-wave superfluidity with

ultracold fermionic atoms loaded in two-dimensional optical superlattices. Our

scheme consists in preparing an array of nearest-neighbor coupled square

plaquettes or ``superplaquettes'' and using them as building blocks to

construct a d-wave superfluid state. We describe how to use the coherent

dynamical evolution in such a system to experimentally probe the pairing

mechanism. We also derive the zero temperature phase diagram of the fermions in

a checkerboard lattice (many weakly coupled plaquettes) and show that by tuning

the inter-plaquette tunneling spin-dependently or varying the filling factor

one can drive the system into a d-wave superfluid phase or a Cooper pair

density wave phase. We discuss the use of noise correlation measurements to

experimentally probe these phases.

\\ ( http://arxiv.org/abs/0806.0166 , 642kb)

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arXiv:0806.0221

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

Title: Luttinger liquid coupled to Bose-Einstein condensation reservoirs

Authors: Fang Cheng, Guobao Zhu, W. M. Liu, Guanghui Zhou

Categories: cond-mat.str-el cond-mat.dis-nn

\\

We investigate the transport properties for a Luttinger liquid coupled to two

identical Bose-Einstein condensation reservoirs. Using the approach of equation

of motion for the Green function of the system, we find that the distance

between the two resonant transmission probability peaks of the system is

determined by the bosonic interaction strengths, and the sharpness of these

resonant peaks is mainly determined by the Rabi frequency and phase of the

Bose-Einstein condensation reservoir. These results for the proposed system

involving a Luttinger liquid may build a bridge between the controling

transport properties of cold atom in atom physics and the interacting boson

transport in low-dimensional condensed matter physics.

\\ ( http://arxiv.org/abs/0806.0221 , 18kb)

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arXiv:0806.0244

Date: Mon, 2 Jun 2008 10:11:39 GMT (433kb,D)

Title: Decay of multiply charged vortices at nonzero temperatures

Authors: Tomasz Karpiuk, Miroslaw Brewczyk, Mariusz Gajda, Kazimierz Rzazewski

Categories: cond-mat.other

Comments: 4 pages, 6 figures

\\

We study the instability of multiply charged vortices in the presence of

thermal atoms and find various scenarios of splitting of such vortices. The

onset of the decay of a vortex is always preceded by the increase of a number

of thermal (uncondensed) atoms in the system and manifests itself by the sudden

rise of the amplitude of the oscillations of the quadrupole moment. Our

calculations show that the decay time gets shorter when the multiplicity of a

vortex becomes higher.

\\ ( http://arxiv.org/abs/0806.0244 , 433kb)

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arXiv:0806.0262

Date: Mon, 2 Jun 2008 12:13:46 GMT (83kb)

Title: Effects of Axial Vorticity in Elongated Mixtures of Bose-Einstein

Condensates

Authors: L. Salasnich, B.A. Malomed and F. Toigo

Categories: cond-mat.other cond-mat.stat-mech

Comments: 4 pages, 3 figures

Journal-ref: Phys. Rev. A 77, 035601 (2008)

DOI: 10.1103/PhysRevA.77.035601

\\

We consider a meniscus between rotating and nonrotating species in the

Bose-Einstein condensate (BEC) with repulsive inter-atomic interactions,

confined to a pipe-shaped trap. In this setting, we derive a system of coupled

one-dimensional (1D) nonpolynomial Schrodinger equations (NPSEs) for two

mean-field wave functions. Using these equations, we analyze the phase

separation/mixing in the pipe with periodic axial boundary conditions, i.e. in

a toroidal configuration. We find that the onset of the mixing, in the form of

suction, i.e., filling the empty core in the vortical component by its

nonrotating counterpart, crucially depends on the vorticity of the first

component, and on the strengths of the inter-atomic interactions.

\\ ( http://arxiv.org/abs/0806.0262 , 83kb)

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arXiv:0806.0212

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

Title: Paired atom laser beams created via four-wave mixing

Authors: R. G. Dall, L. J. Byron, A. G. Truscott, G. R. Dennis, M. T. Johnsson,

J. J. Hope

Categories: quant-ph

Comments: 5 pages, 3 figures

\\

A simple method to create paired atom laser beams from a metastable helium

atom laser via four-wave mixing is demonstrated. Radio frequency outcoupling is

used to outcouple atoms from a Bose Einstein condensate near the center of the

condensate and initiate scattering between trapped and untrapped atoms. The

unequal strengths of the interactions for different internal states allows an

energy resonance for the creation of pairs of atoms scattered from the

zero-velocity condensate. The resulting scattered beams are well separated from

the main atom laser in the 2-dimensional transverse atom laser profile.

Numerical simulations of the system are in good agreement with the observed

atom laser spatial profiles, and verify that the scattered beams are generated

by a four-wave mixing process, suggesting that the beams are correlated.

\\ ( http://arxiv.org/abs/0806.0212 , 600kb)

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arXiv:0806.0270

Date: Sat, 31 May 2008 11:22:27 GMT (1189kb)

Title: The Einstein-Podolsky-Rosen paradox - a fundamental challenge and a tool

for quantum engineering

Authors: M. D. Reid, P. D. Drummond, E. G. Cavalcanti, W. P. Bowen, P. K. Lam,

H. A. Bachor, U. L. Andersen, G. Leuchs

Categories: quant-ph

Comments: Colloquium submitted to Reviews of Modern Physics

\\

This Colloquium examines the\textbf{\emph{}}field of the EPR paradox, from

the original paper of Einstein, Podolsky and Rosen, through to modern

theoretical proposals of how to realize both the continuous-variable and

discrete versions of the EPR paradox. We analyze the relationship with

entanglement and Bell's theorem, and summarize the progress to date towards

experimental confirmation of the EPR paradox, with a detailed treatment of the

continuous-variable paradox in laser-based experiments. Practical techniques

covered include continuous-wave parametric amplifier and optical fibre quantum

soliton experiments. We discuss current proposals for extending EPR experiments

to massive-particle systems, including spin-squeezing, atomic position

entanglement, and quadrature entanglement in ultra-cold atoms. Finally, we

examine applications of this technology to quantum key distribution, quantum

teleportation and entanglement-swapping.

\\ ( http://arxiv.org/abs/0806.0270 , 1189kb)

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arXiv:0806.0164

Date: Sun, 1 Jun 2008 19:03:15 GMT (404kb)

Title: Operating an atom interferometer beyond its linear range

Authors: S\'ebastien Merlet (SYRTE), J. Le Gou\"et (SYRTE), Quentin Bodart

(SYRTE), Andre Clairon (SYRTE, BNM-SYRTE), Arnaud Landragin (SYRTE), Franck

Pereira Dos Santos (SYRTE), Pierre Rouchon (CAS, ENSMP)

Categories: physics.atom-ph

Comments: 20 pages, 8 figures

\\

In this paper, we show that an atom interferometer inertial sensor, when

associated to the auxiliary measurement of external vibrations, can be operated

beyond its linear range and still keep a high acceleration sensitivity. We

propose and compare two measurement procedures (fringe fitting and nonlinear

lock) that can be used to extract the mean phase of the interferometer when the

interferometer phase fluctuations exceed $2\pi$. Despite operating in the urban

environment of inner Paris without any vibration isolation, the use of a low

noise seismometer for the measurement of ground vibrations allows our atom

gravimeter to reach at night a sensitivity as good as $5.5\times10^{-8}$g at 1

s. Robustness of the measurement to large vibration noise is also demonstrated

by the ability of our gravimeter to operate during an earthquake with excellent

sensitivity. Our high repetition rate allows for recovering the true low

frequency seismic vibrations, ensuring proper averaging. Such techniques open

new perspectives for applications in other fields, such as navigation and

geophysics.

\\ ( http://arxiv.org/abs/0806.0164 , 404kb)

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arXiv:0806.0379

Date: Mon, 2 Jun 2008 20:02:26 GMT (155kb)

Title: Topological Zero modes in fermionic condensate phases on the honeycomb

lattice

Authors: Doron L. Bergman and Karyn Le Hur

Categories: cond-mat.supr-con

\\

We investigate a number of fermionic condensate phases on the honeycomb

lattice, to determine whether topological defects (vortices and edges) in these

phases can support bound states with zero energy. We argue that zero modes

bound to vortices and at edges are not only connected, but should in fact be

\emph{identified}. Recently, it has been shown that the simplest s-wave

superconducting state for the Dirac fermion approximation of the honeycomb

lattice at precisely half filling, supports (near) zero modes inside the cores

of vortices (P. Ghaemi and F. Wilczek, 2007). We find that the zero modes are

not unique neither to this phase, nor to half filling. In addition, we find

that the \emph{exact} wavefunctions for vortex bound zero modes, as well as the

complete edge state spectrum of the phases we discuss. The zero modes in all

the phases we examine have even-numbered degeneracy, and as such pairs of any

Majorana modes are simply equivalent to one ordinary fermion. As a result,

contrary to bound state zero modes in $p_x+i p_y$ superconductors, vortices

here do \emph{not} exhibit non-Abelian exchange statistics. Finally, we make a

number of suggestions to determine experimentally the existence of these unique

bound states in graphene or cold atom fermionic condensates.

\\ ( http://arxiv.org/abs/0806.0379 , 155kb)

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arXiv:0806.0419

Date: Tue, 3 Jun 2008 01:35:29 GMT (104kb)

Title: Odd-frequency pairing in binary boson-fermion cold atom mixtures

Authors: Ryan M. Kalas, Alexander V. Balatsky, Dmitry Mozyrsky

Categories: cond-mat.other

Comments: 4 pages, 1 figure

\\

We study fermionic superfluidity in a boson-single-species-fermion cold atom

mixture. We argue that apart from the standard p-wave fermion pairing mediated

by the phonon field of the boson gas, the system also exhibits s-wave pairing

with the anomalous correlator being an odd function of time or frequency. We

show that such a superfluid phase, while typically having a much higher

transition temperature than the p-wave, may only exist for sufficiently strong

couplings between fermions and bosons. These conditions for odd-frequency

pairing are favorable close to the value of the coupling at which the mixture

phase-separates. We evaluate the finite-temperature phase diagram for this

system and discuss the experimental realization and signatures of this novel

superfluid in ultracold atomic gases.

\\ ( http://arxiv.org/abs/0806.0419 , 104kb)

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arXiv:0806.0423

Date: Tue, 3 Jun 2008 02:39:37 GMT (114kb)

Title: Universality and Anomalous Mean-Field Breakdown of Symmetry-Breaking

Transitions in A Coupled Two-Component Condensate

Authors: Chaohong Lee

Categories: cond-mat.mes-hall cond-mat.other

Comments: 4 pages, 3 eps figures

\\

We study both mean-field and full quantum dynamics of symmetry-breaking

transitions in a coupled two-component Bose-Einstein condensate. By controlling

s-wave scattering lengths and coupling strength, it is possible to stimulate

symmetry-breaking transitions between normal and spontaneously polarized ground

states. In static transitions, the probability maxima of full quantum ground

states correspond to the mean-field ground states. In dynamical transitions,

due to the appearance of gapless Bogoliubov excitations, the mean-field

dynamics obeys universal Kibble-Zurek-like scalings. Both mean-field and full

quantum defect modes appear as damped oscillations, but they appear at

different critical points and undergo different oscillation regimes. The

anomalous breakdown of mean-field dynamics induced by symmetry-breaking

transitions depends on the transition direction.

\\ ( http://arxiv.org/abs/0806.0423 , 114kb)

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arXiv:0806.0461

Date: Tue, 3 Jun 2008 08:10:51 GMT (437kb)

Title: Creating a supersolid in one-dimensional Bose mixtures

Authors: L. Mathey, Ippei Danshita, and Charles W. Clark

Categories: cond-mat.other

Comments: 4 pages, 5 figures

\\

We identify a one-dimensional supersolid phase in a binary mixture of

near-hardcore bosons with weak, local inter-species repulsion. We find

realistic conditions under which such a phase, defined here as the coexistence

of quasi-superfluidity and quasi-charge density wave order, can be produced and

observed in finite ultra-cold atom systems in a harmonic trap. Our analysis is

based on Luttinger liquid theory supported with numerical calculations using

the time-evolving block decimation method. Clear experimental signatures of

these two orders can be found, respectively, in time-of-flight interference

patterns, and the structure factor S(k) derived from density correlations.

\\ ( http://arxiv.org/abs/0806.0461 , 437kb)

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arXiv:0806.0465

Date: Tue, 3 Jun 2008 08:44:53 GMT (794kb)

Title: Correlation Effects on Atom Density Profiles of 1-D and 2-D Polarized

Atomic-Fermi-Gas Loaded on Optical Lattice

Authors: M. Machida, S. Yamada, M. Okumura, Y. Ohashi, H. Matsumoto

Categories: cond-mat.str-el

Comments: A reference is added to the published version

Journal-ref: Phys. Rev. A 77, 053614 (2008)

DOI: 10.1103/PhysRevA.77.053614

\\

We investigate effects of optical lattice potential in one- and

two-dimensional two-component trapped Fermi gases with population imbalances.

Using the exact diagonalization and the density matrix renormalization group

methods complementarily, we calculate the atom density profile from the ground

state many-body wavefunction as a function of attractive interaction strength

for various population imbalances. The numerical results reveal that although a

phase separation between the superfluid core and the shell cloud of excess

atoms occurs as observed in experiments without the optical lattice, the

population imbalance generally remains in the core region in contrast to the

non-lattice cases. The essence of the numerical results in a strong attractive

regime can be explained by an effective model composed of Cooper pairs and

excess major fermions.

\\ ( http://arxiv.org/abs/0806.0465 , 794kb)

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arXiv:0806.0470

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

Title: Supercurrent behavior of low-energy Bogoliubov phonon and anomalous

tunneling effect in a Bose-Einstein condensate

Authors: Yoji Ohashi, and Shunji Tsuchiya

Categories: cond-mat.other

Comments: 22 pages, 3 figures

\\

We investigate tunneling properties of Bogoliubov mode in a Bose-Einstein

condensate. Using an exactly solvable model with a delta-functional barrier, we

show that each component in the two-component wavefunction (u,v) of low-energy

Bogoliubov phonon has the same form as the condensate wavefunction in the

supercurrent state. As a result, the currents J_u and J_v associated with u and

v, respectively, have the same tunneling properties as those of supercurrent

carried by condensate. Thus, the tunneling of low-energy Bogoliubov phonon

described by the tunneling of these two currents shows perfect transmission. We

also show that the supercurrent behaviors of Bogoliubov phonon still exist in

the presence of supercurrent carried by condensate, except in the critical

supercurrent state. In the critical current state, the perfect transmission is

absent, because J_u or J_v exceeds their upper limit given by the critical

value of the supercurrent associated with the condensate. Our results

consistently explain the recently proposed two tunneling phenomena associated

with Bogoliubov phonon, namely, the anomalous tunneling effect (perfect

transmission in the low-energy limit) and the breakdown of the perfect

transmission in the critical supercurrent state.

\\ ( http://arxiv.org/abs/0806.0470 , 21kb)

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arXiv:0806.0587

Date: Tue, 3 Jun 2008 17:02:38 GMT (149kb,D)

Title: Collisional stability of a three-component degenerate Fermi gas

Authors: T. B. Ottenstein, T. Lompe, M. Kohnen, A. N. Wenz and S. Jochim

Categories: cond-mat.other

\\

We report on the creation of a degenerate Fermi gas consisting of a balanced

mixture of atoms in three different hyperfine states of $^6$Li. This new system

consists of three distinguishable Fermions with different and tunable

interparticle scattering lengths $a_{12}$, $a_{13}$ and $a_{23}$. We are able

to prepare samples containing $5 \cdot 10^4$ atoms in each state at a

temperature of about $215 $nK, which corresponds to $T/T_F \approx 0.37$. We

investigated the collisional stability of the gas for magnetic fields between 0

and 600 G and found a prominent loss feature at 130 G. From lifetime

measurements we determined three-body loss coefficients, which we found to vary

over nearly three orders of magnitude.

\\ ( http://arxiv.org/abs/0806.0587 , 149kb)

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arXiv:0806.0598

Date: Tue, 3 Jun 2008 17:21:02 GMT (117kb)

Title: Fermion mediated interactions in a dilute Bose-Einstein condensate

Authors: D. H. Santamore, Eddy Timmermans

Categories: cond-mat.stat-mech

Comments: 16 pages, 6 figures

\\

We develop a diagrammatic perturbation treatment to calculate the

zero-temperature equation of state of the dilute gas mixture of a single spin

component Bose-Einstein condensate (BEC) and a normal Fermi-gas of

indistinguishable (single spin) fermion particles. We find that the mean-field

description breaks down near the mechanical instability related to the phase

separation phenomenon. Our analysis shows that the instability is caused by the

competition of the usual short-range and fermion-mediated boson-boson

interactions, which result in a boson compressibility that diverges. In the low

BEC-density limit, we show that the diagrammatic analysis simplifies, we sum

part of the higher order diagrams and we discuss the effects of other higher

order contributions.

\\ ( http://arxiv.org/abs/0806.0598 , 117kb)

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arXiv:0806.0457

Date: Tue, 3 Jun 2008 07:53:31 GMT (159kb)

Title: Criteria for generalized macroscopic and mesoscopic quantum coherence

Authors: E. G. Cavalcanti and M. D. Reid

Categories: quant-ph

Comments: 15 pages, accepted for publication in Phys. Rev. A

\\

We consider macroscopic, mesoscopic and "S-scopic" quantum superpositions of

eigenstates of an observable, and develop some signatures for their existence.

We define the extent, or size $S$ of a superposition, with respect to an

observable \hat{x}, as being the range of outcomes of \hat{x} predicted by that

superposition. Such superpositions are referred to as generalized $S$-scopic

superpositions to distinguish them from the extreme superpositions that

superpose only the two states that have a difference $S$ in their prediction

for the observable. We also consider generalized $S$-scopic superpositions of

coherent states. We explore the constraints that are placed on the statistics

if we suppose a system to be described by mixtures of superpositions that are

restricted in size. In this way we arrive at experimental criteria that are

sufficient to deduce the existence of a generalized $S$-scopic superposition.

The signatures developed are useful where one is able to demonstrate a degree

of squeezing. We also discuss how the signatures enable a new type of

Einstein-Podolsky-Rosen gedanken experiment.

\\ ( http://arxiv.org/abs/0806.0457 , 159kb)

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arXiv:0806.0620

Date: Tue, 3 Jun 2008 20:00:14 GMT (8kb)

Title: Microscopic justification of the Kelvin's statement on thermodynamics

Authors: Anatoli Polkovnikov

Categories: cond-mat.stat-mech

Comments: 5 pages, no figures

\\

We prove the theorem that in a cyclic process over a Hamiltonian system the

energy of the system can either increase or stay the same provided that (i) the

initial density matrix of the system is stationary (i.e. diagonal in the energy

eigenbasis) and (ii) the initial occupancy of different many body levels given

by diagonal elements of the density matrix is a monotonically decreasing

function of energy, i.e. $\rho_{n}\leq \rho_{m}$ if $E_n\geq E_m$. This

theorem, in particular implies, that it is impossible to extract work from an

isolated system satisfying the initial constraints by reducing its energy,

which in turn is equivalent to the Kelvin's formulation of the second law of

thermodynamics and which can be used to prove impossibility of the {\em

perpetuum mobile} of the second type.

\\ ( http://arxiv.org/abs/0806.0620 , 8kb)

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arXiv:0806.0791

Date: Wed, 4 Jun 2008 14:33:21 GMT (30kb)

Title: Long Cycles in the Infinite-Range-Hopping Bose-Hubbard Model with Hard

Cores

Authors: G. Boland, J.V. Pul\'e

Categories: cond-mat.stat-mech

Comments: 26 pages, 2 figures. To appear in JSP

\\

In this paper we study the relation between long cycles and Bose-Condensation

in the Infinite range Bose-Hubbard Model with a hard core interaction. We

calculate the density of particles on long cycles in the thermodynamic limit

and find that the existence of a non-zero long cycle density coincides with the

occurrence of Bose-Einstein condensation but this density is not equal to that

of the Bose condensate.

\\ ( http://arxiv.org/abs/0806.0791 , 30kb)

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arXiv:0806.0814

Date: Wed, 4 Jun 2008 17:27:43 GMT (253kb)

Title: Vortex Formation by an off-axis oscillating spherical quadrupole field

in a Bose-Einstein condensate

Authors: E. A. L. Henn, J. A. Seman, E. R. F. Ramos, M. Caracanhas, P.

Castilho, E. P. Olimpio, G. Roati, D. V. Magalh\~aes, K. M. F. Magalh\~aes,

V.S. Bagnato

Categories: cond-mat.other cond-mat.mes-hall

Comments: 4 pages, 5 figures

\\

We present a new technique to generate vortices in gaseous Bose-Einstein

condensates. The method consists in superimpose an oscillating spherical

quadupole magnetic field to the QUIC magnetic trap where we have produced a

sample of 1-2$\times10^5$ Bose condensed $^{87}$Rb atoms. The external field

symmetry axis is not parallel to the trap axis nor its center coincides with

the trapping field minimum position. For small amplitudes of the external

excitation field we observe a tilt of the cloud axis. Increasing the amplitude

we observe formation of an increasing number of vortices in the sample.

Shot-to-shot variations in both vortex number and position within the condensed

cloud are observed, probably due to the intrinsic vortex nucleation dynamics.

We discuss the possible formation of vortices and anti-vortices in the sample.

\\ ( http://arxiv.org/abs/0806.0814 , 253kb)

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arXiv:0806.0821

Date: Wed, 4 Jun 2008 17:23:58 GMT (96kb)

Title: Formation of deeply bound molecules via chainwise adiabatic passage

Authors: Elena Kuznetsova, Philippe Pellegrini, Robin C\^ot\'e, M.D. Lukin,

S.F. Yelin

Categories: quant-ph

\\

We suggest and analyze a novel technique for efficient and robust creation of

dense ultracold molecular ensembles in their ground rovibrational state. In our

approach a molecule is brought to the ground state through a series of

intermediate vibrational states via a {\em multistate chainwise Stimulated

Raman Adiabatic Passage} (c-STIRAP) technique. We study the influence of the

intermediate states decay on the transfer process and suggest an approach that

minimizes the population of these states, resulting in a maximal transfer

efficiency. As an example, we analyze the formation of $^{87}$Rb$_{2}$ starting

from an initial Feshbach molecular state and taking into account major decay

mechanisms due to inelastic atom-molecule and molecule-molecule collisions.

Numerical analysis suggests a transfer efficiency $>$ 90%, even in the presence

of strong collisional relaxation as are present in a high density atomic gas.

\\ ( http://arxiv.org/abs/0806.0821 , 96kb)

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\\

arXiv:0806.0663

Date: Tue, 3 Jun 2008 23:47:02 GMT (605kb)

Title: Controlling atomic vapor density in paraffin-coated cells using

light-induced atomic desorption

Authors: T. Karaulanov, M. T. Graf, D. English, S. M. Rochester, Y. Rosen, K.

Tsigutkin, D. Budker, E. B. Alexandrov, M. V. Balabas, D. F. Jackson Kimball,

F. A. Narducci, S. Pustelny, V. V. Yashchuk

Categories: physics.atom-ph

Comments: 9 pages, 9 figures

\\

Atomic-vapor density change due to light induced atomic desorption (LIAD) is

studied in paraffin-coated rubidium, cesium, sodium and potassium cells. In the

present experiment, low-intensity probe light is used to obtain an absorption

spectrum and measure the vapor density, while light from an argon-ion laser or

discharge lamp is used for desorption. Potassium is found to exhibit

significantly weaker LIAD from paraffin compared to Rb and Cs, and we were

unable to observe LIAD with sodium. A simple LIAD model is applied to describe

the observed vapor-density dynamics, and the role of the cell's stem is

explored through the use of cells with lockable stems. The results of this work

could be used to assess the use of LIAD for vapor-density control in

magnetometers, clocks, and gyroscopes utilizing coated cells.

\\ ( http://arxiv.org/abs/0806.0663 , 605kb)

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\\

arXiv:0806.0990

Date: Thu, 5 Jun 2008 13:52:07 GMT (1098kb)

Title: Excitations of attractive 1-D bosons: Binding vs. fermionization

Authors: Emmerich Tempfli, Sascha Z\"ollner, Peter Schmelcher

Categories: cond-mat.other

Comments: 7 pages, 5 figures

\\

The stationary states of few bosons in a one-dimensional harmonic trap are

investigated throughout the crossover from weak to strongly attractive

interactions. For sufficient attraction, three different classes of states

emerge: (i) N-body bound states, (ii) bound states of smaller fragments, and

(iii) gas-like states that fermionize, that is, map to ideal fermions in the

limit of infinite attraction. The two-body correlations and momentum spectra

characteristic of the three classes are discussed, and the results are

illustrated using the soluble two-particle model.

\\ ( http://arxiv.org/abs/0806.0990 , 1098kb)

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\\

arXiv:0804.2678 (*cross-listing*)

Date: Thu, 17 Apr 2008 03:37:27 GMT (93kb)

Date (revised v2): Wed, 4 Jun 2008 17:50:18 GMT (93kb)

Title: Density Functional Theory for non-relativistic Fermions in the Unitarity

Limit

Authors: Gautam Rupak and Thomas Schaefer (North Carolina State University)

Categories: nucl-th cond-mat.other

Comments: 16 pages, improved matching procedure (leads to a very small

correction in the final result)

\\

We derive an energy density functional for non-relativistic spin one-half

fermions in the limit of a divergent two-body scattering length. Using an

epsilon expansion around d=4-epsilon spatial dimensions we compute the

coefficient of the leading correction beyond the local density approximation

(LDA). In the case of N fermionic atoms trapped in a harmonic potential this

correction has the form E=E_(LDA)(1+c_s (3N)^(-2/3)), where E_(LDA) is the

total energy in LDA approximation. At next-to-leading order in the epsilon

expansion we find c_s=2.41, which is significantly larger than the result for

non-interacting fermions, c_s=0.5.

\\ ( http://arxiv.org/abs/0804.2678 , 93kb)

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\\

arXiv:0806.0956

Date: Thu, 5 Jun 2008 13:46:44 GMT (207kb)

Title: A compact dual atom interferometer gyroscope based on laser-cooled

rubidium

Authors: T. M\"uller, M. Gilowski, M. Zaiser, T. Wendrich, W. Ertmer, and E. M.

Rasel

Categories: physics.atom-ph

Comments: 9 pages, 8 figures

\\

We present a compact and transportable inertial sensor for precision sensing

of rotations and accelerations. The sensor consists of a dual Mach-Zehnder-type

atom interferometer operated with laser-cooled $^{87}$Rb. Raman processes are

employed to coherently manipulate the matter waves. We describe and

characterize the experimental apparatus. A method for passing from a compact

geometry to an extended interferometer with three independent atom-light

interaction zones is proposed and investigated. The extended geometry will

enhance the sensitivity by more than two orders of magnitude which is necessary

to achieve sensitivities better than $10^{-8} $rad/s/$\sqrt{\rm Hz}$.

\\ ( http://arxiv.org/abs/0806.0956 , 207kb)

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\\

arXiv:0805.4650

Date: Fri, 30 May 2008 01:18:52 GMT (49kb)

Title: The w-index: A significant improvement of the h-index

Authors: Qiang Wu

Categories: physics.soc-ph physics.data-an

Comments: 7 pages, 3 tables

\\

I propose a new measure, the w-index, as a particularly simple and useful way

to assess the integrated impact of a researcher's work, especially his or her

excellent papers. The w-index can be defined as follow: A researcher has index

w if w of his/her papers have at least 10w citations each, and the other papers

have fewer than 10(w+1) citations.

\\ ( http://arxiv.org/abs/0805.4650 , 49kb)

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\\

arXiv:0806.0974

Date: Thu, 5 Jun 2008 13:55:51 GMT (33kb)

Title: Universality of citation distributions: towards an objective measure of

scientific impact

Authors: Filippo Radicchi, Santo Fortunato, Claudio Castellano

Categories: physics.soc-ph physics.data-an

Comments: 14 pages, 5 figures

\\

We study the distributions of citations received by a single publication

within several disciplines, spanning all fields of science. We show that the

probability that a paper is cited $c$ times has large variations between

different disciplines, but all distributions are rescaled on a universal curve

when the relative indicator $c/c_0$ is considered, where $c_0$ is the average

number of citations per paper for the discipline. In addition we show that the

same universal behavior occurs when citation distributions of papers published

in the same field, but in different years, are compared. These findings provide

a strong validation of $c/c_0$ as an unbiased indicator for citation

performance across disciplines and years. Based on this indicator, we introduce

a generalization of the h-index suitable for comparing scientists working in

different fields.

\\ ( http://arxiv.org/abs/0806.0974 , 33kb)

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The replacements:

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\\

arXiv:0802.1882

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

Title: Quasiparticles, coherence and nonlinearity: exact simulations of

RF-spectroscopy of strongly interacting one-dimensional Fermi gases

Authors: M. J. Leskinen, V. Apaja, J. Kajala, P. Torma

Categories: cond-mat.supr-con cond-mat.other

Comments: 4 pages, 3 figures, revised version

\\ ( http://arxiv.org/abs/0802.1882 , 490kb)

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\\

arXiv:0706.0834

replaced with revised version Mon, 2 Jun 2008 09:37:22 GMT (12kb)

Title: Resonant Scattering of Ultracold Atoms in Low Dimensions

Authors: Ludovic Pricoupenko (LPTMC)

Categories: cond-mat.other

Journal-ref: Physical Review Letters 100 (2008) 170404

DOI: 10.1103/PhysRevLett.100.170404

\\ ( http://arxiv.org/abs/0706.0834 , 12kb)

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\\

arXiv:0706.3686

replaced with revised version Mon, 2 Jun 2008 08:37:42 GMT (378kb)

Title: Spontaneous rotating vortex lattices in a pumped decaying condensate

Authors: Jonathan Keeling, Natalia G. Berloff

Categories: cond-mat.other

Comments: Updated title and introduction. 4 pages, 3 figures

\\ ( http://arxiv.org/abs/0706.3686 , 378kb)

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\\

arXiv:0711.2697

replaced with revised version Sun, 1 Jun 2008 00:13:19 GMT (177kb)

Title: Exact exponents of edge singularities in dynamic correlation functions

of 1D Bose gas

Authors: Adilet Imambekov and Leonid I. Glazman

Categories: cond-mat.str-el

Comments: final published version

Journal-ref: Phys. Rev. Lett. 100, 206805 (2008)

DOI: 10.1103/PhysRevLett.100.206805

\\ ( http://arxiv.org/abs/0711.2697 , 177kb)

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\\

arXiv:0802.3164 (*cross-listing*)

replaced with revised version Sat, 31 May 2008 11:34:58 GMT (226kb)

Title: A non-Hermitian $PT-$symmetric Bose-Hubbard model: eigenvalue rings from

unfolding higher-order exceptional points

Authors: E. M. Graefe, U. Guenther, H. J. Korsch, A. E. Niederle

Categories: math-ph cond-mat.other math.MP quant-ph

Comments: minor changes

Journal-ref: J. Phys. A: Math. Theor. 41 (2008) 255206

DOI: 10.1088/1751-8113/41/25/255206

\\ ( http://arxiv.org/abs/0802.3164 , 226kb)

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\\

arXiv:0803.2947

replaced with revised version Tue, 3 Jun 2008 08:00:52 GMT (214kb,D)

Title: Spreading of correlations and entanglement after a quench in the

one-dimensional Bose-Hubbard model

Authors: Andreas Laeuchli, Corinna Kollath

Categories: cond-mat.other

Comments: 19 pages, 9 figures

Journal-ref: J. Stat. Mech. (2008) P05018

DOI: 10.1088/1742-5468/2008/05/P05018

\\ ( http://arxiv.org/abs/0803.2947 , 214kb)

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\\

arXiv:0711.4615

replaced with revised version Mon, 2 Jun 2008 20:40:34 GMT (44kb)

Title: Equation of State and Phases of Polarized Unitary Fermi Gas

Authors: S. Y. Chang

Categories: physics.atom-ph physics.atm-clus

Comments: 4 pages,4 figures

Journal-ref: Phys. Rev. A 77, 051602 (R), 2008

\\ ( http://arxiv.org/abs/0711.4615 , 44kb)

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\\

arXiv:0712.2978

replaced with revised version Tue, 3 Jun 2008 11:19:35 GMT (2kb)

Title: Comment on "Multibeam atom laser: Coherent atom beam splitting from a

single far-detuned laser"

Authors: V. A. Kuz'menko

Categories: physics.optics

Comments: 2 pages, new experimental results are discussed

\\ ( http://arxiv.org/abs/0712.2978 , 2kb)

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\\

arXiv:0806.0465

replaced with revised version Thu, 5 Jun 2008 05:38:04 GMT (794kb)

Title: Correlation Effects on Atom Density Profiles of 1-D and 2-D Polarized

Atomic-Fermi-Gas Loaded on Optical Lattice

Authors: M. Machida, S. Yamada, M. Okumura, Y. Ohashi, H. Matsumoto

Categories: cond-mat.str-el

Comments: References are added to the published version

Journal-ref: Phys. Rev. A 77, 053614 (2008)

DOI: 10.1103/PhysRevA.77.053614

\\ ( http://arxiv.org/abs/0806.0465 , 794kb)

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Till next time,

Matt.

-- ========================================================================= Dr M. J. Davis, Senior Lecturer in Physics School of Physical Sciences, email: mdavis_at_physics.uq.edu.au University of Queensland, ph : +61 7 334 69824 Brisbane, QLD 4072, fax : +61 7 336 51242 Australia. http://www.physics.uq.edu.au/people/mdavis/ ========================================================================= Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland =========================================================================Received on Wed Jun 25 2008 - 11:27:48 EST

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