Bose-Einstein condensates in 1D optical lattices -: Compressibility, Bloch bands and elementary excitations
Year: 2003
Authors: Kramer M., Menotti C., Pitaevskii L., Stringari S.
Autors Affiliation: Univ Trent, Dipartimento Fis, I-38050 Povo, Italy; INFM, BEC, I-38050 Povo, Italy; Univ Cattolica Sacro Cuore, Dipartimento Matemat & Fis, I-25121 Brescia, Italy; PL Kapitza Phys Problems Inst, Moscow 117334, Russia.
Abstract: We discuss the Bloch-state solutions of the stationary Gross-Pitaevskii equation and of the Bogoliubov equations for a Bose-Einstein condensate in the presence of a one-dimensional optical lattice. The results for the compressibility, effective mass and velocity of sound are analysed as a function of the lattice depth and of the strength of the two-body interaction. The band structure of the spectrum of elementary excitations is compared with the one exhibited by the stationary solutions (Bloch bands). Moreover, the numerical calculations are compared with the analytic predictions of the tight binding approximation. We also discuss the role of quantum fluctuations and show that the condensate exhibits 3D, 2D or 1D features depending on the lattice depth and on the number of particles occupying each potential well. We finally show how, using a local density approximation, our results can be applied to study the behaviour of the gas in the presence of harmonic trapping.
Journal/Review: EUROPEAN PHYSICAL JOURNAL D
Volume: 27 (3) Pages from: 247 to: 261
KeyWords: Dynamic Structure Factor; Collective Excitations; Bragg Spectroscopy; Superfluid; Atoms; GasDOI: 10.1140/epjd/e2003-00284-4Citations: 108data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2024-10-20References taken from IsiWeb of Knowledge: (subscribers only)