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

Date: Mon, 20 Mar 2006 10:24:50 +1000 (EST)

Date: Mon, 20 Mar 2006 10:24:50 +1000 (EST)

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-- ------------------------------------------------------------------------- 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/ ------------------------------------------------------------------------- ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603273 Date: Fri, 10 Mar 2006 14:54:21 GMT (55kb) Title: Ultracold atomic F=2 spinor gas in an optical lattice Authors: L. Zawitkowski, K. Eckert, A. Sanpera, M.Lewenstein Comments: 6 pages, 1 figure Subj-class: Other \\ We investigate magnetic properties of Mott-insulating phases of ultracold F=2 spinor gases in optical lattices. We derive effective spin Hamiltonians for one and two atoms per site and discuss the possibilities of manipulating the magnetic properties of the system using Feshbach resonances. We discuss low temperature quantum phases for 87Rb and 85Rb. \\ ( http://arXiv.org/abs/cond-mat/0603273 , 55kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603279 Date: Fri, 10 Mar 2006 01:05:34 GMT (975kb) Title: A Hybrid Apparatus for BEC and Cavity QED: Single Atom Detection in Quantum Degenerate Gases Authors: Anton \"{O}ttl, Stephan Ritter, Michael K\"ohl and Tilman Esslinger Comments: A version with improved figure quality can be found at http://www.quantumoptics.ethz.ch Subj-class: Other \\ We present and characterize an experimental system in which we achieve the integration of an ultra-high finesse optical cavity with a Bose-Einstein condensate (BEC). The conceptually novel design of the apparatus for the production of BECs features nested vacuum chambers and an in-vacuo magnetic transport configuration. It grants large scale spatial access to the BEC for samples and probes via a modular and exchangeable "science platform". We are able to produce \87Rb condensates of five million atoms and to output couple continuous atom lasers. The cavity is mounted on the science platform on top of a vibration isolation system. The optical cavity works in the strong coupling regime of cavity quantum electrodynamics (QED) and serves as a quantum optical detector for single atoms. This system enables us to study atom optics on a single particle level and to further develop the field of quantum atom optics. We describe the technological modules and the operation of the combined BEC cavity apparatus. Its performance is characterized by single atom detection measurements for thermal and quantum degenerate atomic beams. The atom laser provides a fast and controllable supply of atoms coupling with the cavity mode and allows for an efficient study of atom field interactions in the strong coupling regime. Moreover, the high detection efficiency for quantum degenerate atoms distinguishes the cavity as a sensitive and weakly invasive probe for cold atomic clouds. \\ ( http://arXiv.org/abs/cond-mat/0603279 , 975kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603284 Date: Fri, 10 Mar 2006 07:55:34 GMT (404kb) Title: Modified Sagnac interferometer for high-sensitivity magneto-optic measurements atcryogenic temperatures Authors: Jing Xia, Peter T. Beyersdorf, Martin M. Fejer, and Aharon Kapitulnik Comments: 3 pages, 3 figures Subj-class: Other \\ We describe a geometry for a Sagnac interferometer with a zero-area Sagnac loop for measuring magneto-optic Kerr effect (MOKE) at cryogenic temperatures. The apparatus is capable of measuring absolute polar Kerr rotation at 1550 nm wavelength without any modulation of the magnetic state of the sample, and is intrinsically immune to reciprocal effects such as linear birefringence and thermal fluctuation. A single strand of polarization-maintaining (PM) fiber is fed into a liquid helium probe, eliminating the need for optical viewports. This configuration makes it possible to conduct MOKE measurements at much lower temperatures than before. With an optical power of only 10 $\mu$W, we demonstrate static Kerr measurements with a shot-noise limited sensitivity of $1\times 10^{-7}$ rad/$\sqrt{\rm Hz}$ from room temperature down to 2K. Typical bias drift was measured to be $3\times 10^{-7}$ rad/hour. \\ ( http://arXiv.org/abs/cond-mat/0603284 , 404kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603289 Date: Fri, 10 Mar 2006 13:07:35 GMT (10kb) Title: The difference of boundary effects between Bose and Fermi systems Authors: Hai Pang, Wu-Sheng Dai, Mi Xie Comments: 8 pages Subj-class: Statistical Mechanics Journal-ref: J. Phys. A: Math. Gen. 39 (2006) 2563-2571 \\ In this paper, we show that there exists an essential difference of boundary effects between Bose and Fermi systems both for Dirichlet and Neumann boundary conditions: at low temperatures and high densities the influence of the boundary on the Bose system depends on the temperature but is independent of the density, but for the Fermi case the influence of the boundary is independent of the temperature but depends on the density, after omitting the negligible high-order corrections. We also show that at high temperatures and low densities the difference of the influence of the boundary between Bose and Fermi systems appears in the next-to-leading order boundary contribution, and the leading boundary contribution is independent of the density. Moreover, for calculating the boundary effects at high temperatures and low densities, since the existence of the boundary modification causes the standard virial expansion to be invalid, we introduce a modified virial expansion. \\ ( http://arXiv.org/abs/cond-mat/0603289 , 10kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603299 Date: Fri, 10 Mar 2006 18:08:43 GMT (26kb) Title: Fermions in optical lattices near a Feshbach resonance: from band insulator to Mott insulator Authors: A. F. Ho Comments: 4 pages, 2 .eps files Subj-class: Mesoscopic Systems and Quantum Hall Effect; Strongly Correlated Electrons \\ We study a model of an equal mixture of two species of fermions in a deep optical lattice at a filling of two fermions per site. At weak inter-species interaction, the system is a band insulator. When the inter-species interaction is tuned via a Feshbach resonance to be larger than an energy related to the energy separation of the first and second Bloch band, atoms populate equally the two Bloch bands. With weak tunneling between sites of the optical lattice, the system becomes a Mott insulator with the low energy effective Hamiltonian of a spin-1 Heisenberg antiferromagnet, because of a Hund's rule like coupling between the two bands. We discuss experimental signatures of these two types of insulators. \\ ( http://arXiv.org/abs/cond-mat/0603299 , 26kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0601122 replaced with revised version Fri, 10 Mar 2006 10:22:37 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 \\ ( http://arXiv.org/abs/cond-mat/0601122 , 38kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0603090 Date: Fri, 10 Mar 2006 12:07:44 GMT (39kb) Title: Finite-dimensional states and entanglement generation for a nonlinear coupler Authors: A. Kowalewska-Kud{\l}aszyk, W. Leo\'nski Comments: Accepted for publication in Physical Review A \\ We discuss a system comprising two nonlinear (Kerr-like) oscillators coupled mutually by a nonlinear interaction. The system is excited by an external coherent field that is resonant to the frequency of one of the oscillators. We show that the coupler evolution can be closed within a finite set of $n$-photon states, analogously as in the \textit{nonlinear quantum scissors} model. Moreover, for this type of evolution our system can be treated as a \textit{Bell-like states} generator. Thanks to the nonlinear nature of both: oscillators and their internal coupling, these states can be generated even if the system exhibits its energy dissipating nature, contrary to systems with linear couplings. \\ ( http://arXiv.org/abs/quant-ph/0603090 , 39kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0603093 Date: Fri, 10 Mar 2006 13:14:40 GMT (678kb) Title: Bloch-Zener oscillations Authors: B. M. Breid, D. Witthaut, and H. J. Korsch \\ It is well known that a particle in a periodic potential with an additional constant force performs Bloch oscillations. Modulating every second period of the potential, the original Bloch band splits into two subbands. The dynamics of quantum particles shows a coherent superposition of Bloch oscillations and Zener tunneling between the subbands, a Bloch-Zener oscillation. Such a system is modelled by a tight-binding Hamiltonian, a system of two minibands with an easily controllable gap. The dynamics of the system is investigated by using an algebraic ansatz leading to a differential equation of Whittaker-Hill type. It is shown that the parameters of the system can be tuned to generate a periodic reconstruction of the wave packet and thus of the occupation probability. As an application, the construction of a matter wave beam splitter and a Mach-Zehnder interferometer is briefly discussed. \\ ( http://arXiv.org/abs/quant-ph/0603093 , 678kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0603095 Date: Fri, 10 Mar 2006 14:26:04 GMT (22kb) Title: Saturation of fidelity in the atom-optics kicked rotor Authors: Sandro Wimberger and Andreas Buchleitner Journal-ref: J. Phys. B: At. Mol. Opt. Phys. 39, L145-L151 (2006) DOI: 10.1088/0953-4075/39/7/L01 \\ We show that the quantum fidelity is accessible to cold atom experiments for a large class of evolutions in periodical potentials, properly taking into account the experimental initial conditions of the atomic ensemble. We prove analytically that, at the fundamental quantum resonances of the atom-optics kicked rotor, the fidelity saturates at a constant, time-independent value after a small number of kicks. The latter saturation arises from the bulk of the atomic ensemble, whilst for the resonantly accelerated atoms the fidelity is predicted to decay slowly according to a power law. \\ ( http://arXiv.org/abs/quant-ph/0603095 , 22kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603317 Date: Mon, 13 Mar 2006 17:11:30 GMT (40kb) Title: Synchronization in the BCS Pairing Dynamics as a Critical Phenomenon Authors: R. A. Barankov and L. S. Levitov Subj-class: Mesoscopic Systems and Quantum Hall Effect; Superconductivity \\ Fermi gas with time-dependent pairing interaction hosts several different dynamical states. Coupling between the collective BCS pairing mode and individual Cooper pair states can make the latter either synchronize or dephase. We describe transition from phase-locked undamped oscillations to Landau-damped dephased oscillations in the collisionless, dissipationless regime as a function of coupling strength. In the dephased regime, we find a second transition at which the long-time asymptotic pairing amplitude vanishes. Using a combination of numerical and analytical methods we establish a continuous (type II) character of both transitions. \\ ( http://arXiv.org/abs/cond-mat/0603317 , 40kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603319 Date: Sun, 12 Mar 2006 11:43:55 GMT (301kb) Title: Simulations of ultracold bosonic atoms in optical lattices with anharmonic traps Authors: Olivier Gygi, Helmut G. Katzgraber, Matthias Troyer, Stefan Wessel, and G. George Batrouni Comments: 8 pages, 8 figures, 2 tables Subj-class: Other \\ We report results of quantum Monte Carlo simulations in the canonical and the grand-canonical ensemble of the two- and three-dimensional Bose-Hubbard model with quadratic and quartic confining potentials. The quantum criticality of the superfluid-Mott insulator transition is investigated both on the boundary layer separating the two coexisting phases and at the center of the traps where the Mott-insulating phase is first established. Recent simulations of systems in quadratic traps have shown that the transition is not in the critical regime due to the finite gradient of the confining potential and that critical fluctuations are suppressed. In addition, it has been shown that quantum critical behavior is recovered in flat confining potentials as they approach the uniform regime. Our results show that quartic traps display a behavior similar to quadratic ones, yet locally at the center of the traps the bulk transition has enhanced critical fluctuations in comparison to the quadratic case. Therefore quartic traps provide a better prerequisite for the experimental observation of true quantum criticality of ultracold bosonic atoms in optical lattices. \\ ( http://arXiv.org/abs/cond-mat/0603319 , 301kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603332 Date: Mon, 13 Mar 2006 03:52:33 GMT (411kb) Title: Mean field phase diagrams of imbalanced Fermi gases near a Feshbach resonance Authors: Hui Hu and Xia-Ji Liu Comments: 4 pages + 5 figures Subj-class: Strongly Correlated Electrons; Superconductivity \\ We propose phase diagrams for an imbalanced (unequal number of atoms or Fermi surface in two pairing hyperfine states) gas of atomic fermions near a broad Feshbach resonance using mean field theory. Particularly, in the plane of interaction and polarization we determine the region for a mixed phase composed of normal and superfluid components. We compare our prediction of phase boundaries with the recent measurment, and find a good qualitative agreement. \\ ( http://arXiv.org/abs/cond-mat/0603332 , 411kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603334 Date: Mon, 13 Mar 2006 14:51:15 GMT (29kb) Title: Phases of Bosons or Fermions in confined optical lattices Authors: H. Heiselberg Comments: 4 pages, 3 figures Subj-class: Superconductivity \\ Phases of Bose or Fermi atoms in optical lattices confined in harmonic traps are studied within the Thomas-Fermi approximation. Critical radii and particle number for onset of Mott insulator states are calculated and phase diagrams shown in 1D, and estimated for 2 and 3D. Methods to observe these and novel phases such as d-wave superconductivity is discussed. Specifically the collective modes are calculated. \\ ( http://arXiv.org/abs/cond-mat/0603334 , 29kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603340 Date: Mon, 13 Mar 2006 10:13:46 GMT (19kb) Title: Calogero-Sutherland gas of ultracold Bose atoms Authors: Yue Yu Comments: 4 pages,1 figure Subj-class: Other; Statistical Mechanics \\ We show that a famous exact soluble one-dimensional system, the Calogero-Sutherland gas with an inverse square long range interaction, can be realized in a cold Bose atom system with a dipole-dipole interaction by dimension reduction. The low-lying excitations are a Luttinger liquid that can be characterized by its exclusion statistics parameter. We hope the ground state and low-lying excitation behaviors may be observed in the time of flight experiment. \\ ( http://arXiv.org/abs/cond-mat/0603340 , 19kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0505657 replaced with revised version Mon, 13 Mar 2006 09:58:39 GMT (442kb) Title: Renormalization group approach to the spin-1 Bose gas Authors: Gergely Szirmai Comments: 7 pages, 5 figures included in text, final version, journal reference added Subj-class: Statistical Mechanics Journal-ref: Eur. Phys. J. D 37, 427-433 (2006) \\ ( http://arXiv.org/abs/cond-mat/0505657 , 442kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0509274 replaced with revised version Mon, 13 Mar 2006 05:33:29 GMT (171kb) Title: Temperature of a trapped unitary Fermi gas at finite entropy Authors: Hui Hu, Xia-Ji Liu, and Peter D. Drummond Comments: 5 pages, and 4 figures; Published version in Phys. Rev. A Subj-class: Superconductivity; Statistical Mechanics Journal-ref: Phys. Rev. A 73, 023617 (2006) DOI: 10.1103/PhysRevA.73.023617 \\ ( http://arXiv.org/abs/cond-mat/0509274 , 171kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0511052 replaced with revised version Sun, 12 Mar 2006 09:41:41 GMT (227kb) Title: Einstein--de Haas Effect in Dipolar Bose-Einstein Condensates Authors: Yuki Kawaguchi, Hiroki Saito, and Masahito Ueda Comments: 4 pages, 4 figures; Final version Subj-class: Other Journal-ref: Phys. Rev. Lett. 96, 080405 (2006) DOI: 10.1103/PhysRevLett.96.080405 \\ ( http://arXiv.org/abs/cond-mat/0511052 , 227kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603190 replaced with revised version Mon, 13 Mar 2006 18:07:44 GMT (18kb) Title: Realization, Characterization, and Detection of Novel Superfluid Phases with Pairing between Unbalanced Fermion Species Authors: Kun Yang Comments: This is an invited contribution to a book titled "Pairing beyond BCS Theory in Fermionic Systems" (Mark Alford, John Clark and Armen Sedrakian, eds.), to be published by World Scientific. 20 pages. V2: added references Subj-class: Superconductivity \\ ( http://arXiv.org/abs/cond-mat/0603190 , 18kb) ------------------------------------------------------------------------------ \\ Paper: physics/0603093 Date: Sun, 12 Mar 2006 19:22:33 GMT (14kb) Title: Regime of Validity of the Pairing Hamiltonian in the Study of Fermi Gases Authors: S. Y. Chang, V. R. Pandharipande Comments: 2 figures, 1 table Subj-class: Atomic Physics \\ The ground state energy and pairing gap of the interacting Fermi gases calculated by the {\it ab initio} stochastic method are compared with those estimated from the Bardeen-Cooper-Schrieffer pairing Hamiltonian. We discuss the ingredients of this Hamiltonian in various regimes of interaction strength. In the weakly interacting ($1/ak_F <<0$) regime the BCS Hamiltonian should describe Landau quasi-particle energies and interactions, on the other hand in the strongly pairing regime, that is $1/ak_F \gtrsim 0$, it becomes part of the bare Hamiltonian. However, the bare BCS Hamiltonian is not adequate for describing atomic gases in the regime of weak to moderate interaction strength $-\infty < 1/ak_F <0$ such as $ak_F \sim -1$. PACS: 05.30.Fk, 03.75.Ss, 21.65.+f \\ ( http://arXiv.org/abs/physics/0603093 , 14kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603362 Date: Tue, 14 Mar 2006 10:48:57 GMT (110kb) Title: Quantum resonance and anti-resonance for a periodically kicked Bose-Einstein Condensate in a one dimensional Box Authors: Dario Poletti, Libin Fu, Jie Liu, and Baowen Li Comments: 7 pages, 7 figures Subj-class: Mesoscopic Systems and Quantum Hall Effect \\ We investigate the quantum dynamics of a periodically kicked Bose-Einstein Condensate confined in a one dimensional (1D) Box both numerically and theoretically, emphasizing on the phenomena of quantum resonance and anti-resonance. The quantum resonant behavior of BEC is different from the single particle case but the anti-resonance condition ($T = 2\pi$ and $\alpha = 0$) is not affected by the atomic interaction. For the anti-resonance case, the nonlinearity (atom interaction) causes the transition between oscillation and quantum beating. For the quantum resonance case, because of the coherence of BEC, the energy increase is oscillating and the rate is dramatically affected by the many-body interaction. We also discuss the relation between the quantum resonant behavior and the KAM or non-KAM property of the corresponding classical system. \\ ( http://arXiv.org/abs/cond-mat/0603362 , 110kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603384 Date: Tue, 14 Mar 2006 17:32:23 GMT (103kb) Title: Expansion of a Fermi Cloud in the BCS-BEC Crossover Authors: Giovanni Diana, Nicola Manini, Luca Salasnich Comments: 4 pages, 3 figures Subj-class: Statistical Mechanics \\ We study the free expansion of a dilute two-component Fermi gas with attractive interspecies interaction in the BCS-BEC crossover. We apply a time-dependent parameter-free density-functional theory by using two choices of the equation of state: an analytic formula based on Monte Carlo data and the mean-field equation of state resulting from the extended BCS equations. The calculated axial and transverse radii and the aspect ratio of the expanding cloud are compared to experimental data on vapors of ^6Li atoms. Remarkably, the mean-field theory shows a better agreement with the experiments than the theory based on the Monte Carlo equation of state. Both theories predict a measurable dependence of the aspect ratio on expansion time and on scattering length. \\ ( http://arXiv.org/abs/cond-mat/0603384 , 103kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603389 Date: Tue, 14 Mar 2006 19:24:44 GMT (979kb) Title: On Dispersive and Classical Shock Waves in Bose-Einstein Condensates and Gas Dynamics Authors: M. A. Hoefer, M. J. Ablowitz, I. Coddington, E. A. Cornell, P. Engels, and V. Schweikhard Comments: 24 pages, 28 figures, submitted to Phys Rev A Subj-class: Other \\ A Bose-Einstein condensate (BEC) is a quantum fluid that gives rise to interesting shock wave nonlinear dynamics. Experiments depict a BEC that exhibits behavior similar to that of a shock wave in a compressible gas, eg. traveling fronts with steep gradients. However, the governing Gross-Pitaevskii (GP) equation that describes the mean field of a BEC admits no dissipation hence classical dissipative shock solutions do not explain the phenomena. Instead, wave dynamics with small dispersion is considered and it is shown that this provides a mechanism for the generation of a dispersive shock wave (DSW). Computations with the GP equation are compared to experiment with excellent agreement. A comparison between a canonical 1D dissipative and dispersive shock problem shows significant differences in shock structure and shock front speed. Numerical results associated with the three dimensional experiment show that three and two dimensional approximations are in excellent agreement and one dimensional approximations are in good qualitative agreement. Using one dimensional DSW theory it is argued that the experimentally observed blast waves may be viewed as dispersive shock waves. \\ ( http://arXiv.org/abs/cond-mat/0603389 , 979kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0511746 replaced with revised version Tue, 14 Mar 2006 16:52:32 GMT (352kb) Title: Strongly correlated Fermi-Bose mixtures in disordered optical lattices Authors: L. Sanchez-Palencia (LCFIO), V. Ahufinger, A. Kantian, Jakub Zakrzewski, A. Sanpera, M. Lewenstein Comments: Proceedings of the 3rd International Workshop on `Theory of Quantum Gases and Quantum Coherence' Proxy: ccsd ccsd-00014953 Subj-class: Other \\ ( http://arXiv.org/abs/cond-mat/0511746 , 352kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0508010 replaced with revised version Mon, 13 Mar 2006 21:16:35 GMT (145kb) Title: Measurement of the separation between atoms beyond diffraction limit Authors: Jun-Tao Chang, Joerg Evers, Marlan O. Scully, and M. Suhail Zubairy Comments: v2: Revised version for publication Journal-ref: Phys. Rev. A 73, 031803(R) (2006) DOI: 10.1103/PhysRevA.73.031803 \\ ( http://arXiv.org/abs/quant-ph/0508010 , 145kb) ------------------------------------------------------------------------------ \\ Paper: physics/0603107 Date: Mon, 13 Mar 2006 22:19:26 GMT (533kb) Title: Ultracold Atoms 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 \\ We study the effect of different heating rates of a dilute Bose gas confined in a quasi-1D finite, leaky box. An optical kicked-rotor is used to transfer energy to the atoms while two repulsive optical beams are used to confine the atoms. The average energy of the atoms is localized after a large number of kicks and the system reaches a nonequilibrium steady state. A numerical simulation of the experimental data suggests that the localization is due to energetic atoms leaking over the barrier. Our data also indicates a correlation between collisions and the destruction of the Bose-Einstein condensate fraction. \\ ( http://arXiv.org/abs/physics/0603107 , 533kb) ------------------------------------------------------------------------------ \\ Paper: physics/0602011 replaced with revised version Tue, 14 Mar 2006 19:46:54 GMT (109kb) Title: Demonstration of a Cold Atom Fountain Electron Electric Dipole Moment Experiment Authors: Jason M. Amini, Charles T. Munger Jr., Harvey Gould Comments: 4 pages, 4 figures, references to neutrino flavor added and grammar corrected Subj-class: Atomic Physics \\ ( http://arXiv.org/abs/physics/0602011 , 109kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603402 Date: Wed, 15 Mar 2006 10:06:58 GMT (20kb) Title: Monte Carlo simulation of boson lattices Authors: Vesa Apaja and Olav F. Syljuasen Comments: 3 pages, 5 figure Subj-class: Statistical Mechanics \\ Boson lattices are theoretically well described by the Hubbard model. The basic model and its variants can be effectively simulated using Monte Carlo techniques. We describe two newly developed approaches, the Stochastic Series Expansion (SSE) with directed loop updates and continuous--time Diffusion Monte Carlo (CTDMC). SSE is a formulation of the finite temperature partition function as a stochastic sampling over product terms. Directed loops is a general framework to implement this stochastic sampling in a non--local fashion while maintaining detailed balance. CTDMC is well suited to finding exact ground--state properties, applicable to any lattice model not suffering from the sign problem; for a lattice model the evolution of the wave function can be performed in continuous time without any time discretization error. Both the directed loop algorithm and the CTDMC are important recent advances in development of computational methods. Here we present results for a Hubbard model for anti--ferromagnetic spin--1 bosons in one dimensions, and show evidence for a dimerized ground state in the lowest Mott lobe. \\ ( http://arXiv.org/abs/cond-mat/0603402 , 20kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603404 Date: Wed, 15 Mar 2006 16:57:37 GMT (136kb) Title: Dynamical vanishing of the order parameter in a fermionic condensate Authors: Emil A. Yuzbashyan and Maxim Dzero Comments: 4+ pages, 3 figures Subj-class: Superconductivity; Other \\ We analyze the dynamics of a condensate of an ultra-cold atomic fermions following an abrupt change of the pairing strength. At long times, the system goes to a non-stationary steady state. The superfluid order parameter asymptotes to a constant value, which we determine exactly. We show that the order parameter vanishes dynamically when the pairing strength is decreased below a certain critical value. In this case, the steady state of the system combines properties of normal and superfluid states - the spectroscopic gap and the condensate fraction vanish, while the superfluid density is nonzero. \\ ( http://arXiv.org/abs/cond-mat/0603404 , 136kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0603138 Date: Wed, 15 Mar 2006 15:59:49 GMT (164kb) Title: Theoretical analysis of the implementation of a quantum phase gate with neutral atoms on atom chips Authors: E. Charron, M. A. Cirone, A. Negretti, J. Schmiedmayer, T. Calarco Comments: 9 pages, 5 color figures \\ We present a detailed, realistic analysis of the implementation of a proposal for a quantum phase gate based on atomic vibrational states, specializing it to neutral rubidium atoms on atom chips. We show how to create a double--well potential with static currents on the atom chips, using for all relevant parameters values that are achieved with present technology. The potential barrier between the two wells can be modified by varying the currents in order to realize a quantum phase gate for qubit states encoded in the atomic external degree of freedom. The gate performance is analyzed through numerical simulations; the operation time is ~10 ms with a performance fidelity above 99.9%. For storage of the state between the operations the qubit state can be transferred efficiently via Raman transitions to two hyperfine states, where its decoherence is strongly inhibited. In addition we discuss the limits imposed by the proximity of the surface to the gate fidelity. \\ ( http://arXiv.org/abs/quant-ph/0603138 , 164kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0603424 Date: Thu, 16 Mar 2006 04:45:22 GMT (267kb) Title: Superfluid Dynamics of a Bose-Einstein Condensate in an Optical Super-Lattice Authors: Aranya B Bhattacherjee Comments: 13 pages Subj-class: Statistical Mechanics \\ We derive and study the Bogoliubov-Bloch spectrum of a Bose-Einstein condensate (BEC) confined in a one-dimensional optical superlattice, using the Bogoliubov approximation and the hydrodynamic theory. We show that a BEC in an optical superlattice experiences atleast two different tunneling parameter and hence behaves like a chain of diatomic lattice. This gives rise to a gapped branch in addition to the gapless acoustical branch in the Bogoliubov-Bloch spectrum. The spectrum strongly depends on the strength of the secondary lattice, the interaction parameter and the number density of atoms. \\ ( http://arXiv.org/abs/cond-mat/0603424 , 267kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0511684 replaced with revised version Thu, 16 Mar 2006 01:36:44 GMT (745kb) Title: Critical fluctuations in a soliton formation of attractive Bose-Einstein condensates Authors: Rina Kanamoto, Hiroki Saito, Masahito Ueda Comments: 14 pages, 13 figures Subj-class: Other Journal-ref: Phys. Rev. A 73, 033611 (2006) \\ ( http://arXiv.org/abs/cond-mat/0511684 , 745kb) ------------------------------------------------------------------------------ \\ Paper: cond-mat/0601147 replaced with revised version Thu, 16 Mar 2006 10:44:43 GMT (888kb) Title: LOFF Pairing vs. Breached Pairing in Asymmetric Fermion Superfluids Authors: Lianyi He, Meng Jin and Pengfei Zhuang Comments: 11 pages, 13 figures, references added Subj-class: Superconductivity \\ ( http://arXiv.org/abs/cond-mat/0601147 , 888kb) ------------------------------------------------------------------------------ \\ Paper: quant-ph/0603147 Date: Thu, 16 Mar 2006 16:10:22 GMT (27kb) Title: Test of the quantumness of atom-atom correlations in a bosonic gas Authors: D. Ivanov and S. Wallentowitz Journal-ref: Europhys. Lett. 73, 499 (2006) DOI: 10.1209/epl/i2005-10435-1 \\ It is shown how the quantumness of atom-atom correlations in a trapped bosonic gas can be made observable. Application of continuous feedback control of the center of mass of the atomic cloud is shown to generate oscillations of the spatial extension of the cloud, whose amplitude can be directly used as a characterization of atom-atom correlations. Feedback parameters can be chosen such that the violation of a Schwarz inequality for atom-atom correlations can be tested at noise levels much higher than the standard quantum limit. \\ ( http://arXiv.org/abs/quant-ph/0603147 , 27kb) ------------------------------------------------------------------------------ \\ Paper: physics/0603127 Date: Wed, 15 Mar 2006 22:38:58 GMT (264kb) Title: Focusing a fountain of neutral cesium atoms with an electrostatic lens triplet Authors: Juris G. Kalnins, Jason M. Amini, Harvey Gould Comments: 8 pages 10 figures Report-no: LBNL-57137 Subj-class: Accelerator Physics; Atomic Physics Journal-ref: Phys. Rev. A72, 043406 (2005) \\ An electrostatic lens with three focusing elements in an alternating-gradient configuration is used to focus a fountain of cesium atoms in their ground (strong-field-seeking) state. The lens electrodes are shaped to produce only sextupole plus dipole equipotentials which avoids adding the unnecessary nonlinear forces present in cylindrical lenses. Defocusing between lenses is greatly reduced by having all of the main electric fields point in the same direction and be of nearly equal magnitude. The addition of the third lens gave us better control of the focusing strength in the two transverse planes and allowed focusing of the beam to half the image size in both planes. The beam envelope was calculated for lens voltages selected to produced specific focusing properties. The calculations, starting from first principles, were compared with measured beam sizes and found to be in good agreement. Application to fountain experiments, atomic clocks, and focusing polar molecules in strong-field-seeking states is discussed. \\ ( http://arXiv.org/abs/physics/0603127 , 264kb) ------------------------------------------------------------------------------Received on Mon Mar 20 2006 - 10:24:50 EST

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