1,475 research outputs found

    Finite temperature dynamical properties of SU(NN) fermionic Hubbard models in the spin-incoherent regime

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    We study strongly correlated Hubbard systems extended to symmetric NN-component fermions. We focus on the intermediate-temperature regime between magnetic superexchange and interaction energy, which is relevant to current ultracold fermionic atom experiments. The NN-component fermions are represented by slave particles, and, by using a diagrammatic technique based on the atomic limit, spectral functions are analytically obtained as a function of temperature, filling factor and the component number NN. We also apply this analytical technique to the calculation of lattice modulation experiments. We compute the production rate of double occupancy induced by modulation of an optical lattice potential. Furthermore, we extend the analysis to take into account the trapping potential by use of the local density approximation. We find an excellent agreement with recent experiments on 173^{173}Yb atoms.Comment: 15 pages, 13 figures, published versio

    Unconventional superfluidity in quasi-one-dimensional systems

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    We show that an unconventional superfluid triggered by spin-orbit coupling is realized for repulsively interacting quasi-one-dimensional fermions. A competition between spin-singlet and -triplet pairings occurs due to the breaking of inversion symmetry. We show that both superfluid correlations decay algebraically with the same exponent except for special coupling constants for which a dominant superfluid is controlled by the spin-orbit coupling. We also discuss a possible experiment to observe such phases with cold atoms.Comment: 5 pages, 2 figure

    Doublon production rate in modulated optical lattices

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    We study theoretically lattice modulation experiments with ultracold fermions in optical lattices. We focus on the regime relevant to current experiments when interaction strength is larger than the bandwidth and temperature is higher than magnetic superexchange energy. We obtain analytical expressions for the rate of doublon production as a function of modulation frequency, filling factor, and temperature. We use local density approximation to average over inhomogeneous density for atoms in a parabolic trap and find excellent agreement with experimentally measured values. Our results suggest that lattice modulation experiments can be used for thermometry of strongly interacting fermionic ensembles in optical lattices.Comment: 7 pages, 6 figures, final versio

    Spectroscopy for cold atom gases in periodically phase-modulated optical lattices

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    The response of cold atom gases to small periodic phase modulation of an optical lattice is discussed. For bosonic gases, the energy absorption rate is given, within linear response theory, by imaginary part of the current correlation function. For fermionic gases in a strong lattice potential, the same correlation function can be probed via the production rate double occupancy. The phase modulation gives thus direct access to the conductivity of the system, as function of the modulation frequency. We give an example of application in the case of one dimensional bosons at zero temperature and discuss the link between the phase- and amplitude-modulation.Comment: 4 pages, 2 figures, final versio

    Dynamics of one-dimensional Bose liquids: Andreev-like reflection at Y-junctions and absence of the Aharonov-Bohm effect

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    We study one dimensional Bose liquids of interacting ultracold atoms in the Y-shaped potential when each branch is filled with atoms. We find that the excitation packet incident on a single Y-junction should experience a negative density reflection analogous to the Andreev reflection at normal-superconductor interfaces, although the present system does not contain fermions. In a ring interferometer type configuration, we find that the transport is completely insensitive to the (effective) flux contained in the ring, in contrast to the Aharonov-Bohm effect of a single particle in the same geometry.Comment: 4 pages, 2 figures, final versio

    Calibration of Photomultiplier Tubes for the Fluorescence Detector of Telescope Array Experiment using a Rayleigh Scattered Laser Beam

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    We performed photometric calibration of the PhotoMultiplier Tube (PMT) and readout electronics used for the new fluorescence detectors of the Telescope Array (TA) experiment using Rayleigh scattered photons from a pulsed nitrogen laser beam. The experimental setup, measurement procedure, and results of calibration are described. The total systematic uncertainty of the calibration is estimated to be 7.2%. An additional uncertainty of 3.7% is introduced by the transport of the calibrated PMTs from the laboratory to the TA experimental site.Comment: 43 pages, 15 figure
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