Ultracold bosons in lattices with binary disorder

K. V. Krutitsky, M. Thorwart, R. Egger, and R. Graham
Phys. Rev. A 77, 053609 – Published 16 May 2008

Abstract

Quantum phases of ultracold bosons with repulsive interactions in lattices in the presence of quenched disorder are investigated. The disorder is assumed to be caused by the interaction of the bosons with impurity atoms having a large effective mass. The system is described by the Bose-Hubbard Hamiltonian with random on-site energies which have a discrete binary probability distribution. The phase diagram at zero temperature is calculated using several methods like a strong-coupling expansion, an exact numerical diagonalization, and a Bose-Fermi mapping valid in the hard-core limit. It is shown that the Mott-insulator phase exists for any strength of disorder in contrast to the case of continuous probability distribution. We find that the compressibility of the Bose glass phase varies in a wide range and can be extremely low. Furthermore, we evaluate experimentally accessible quantities like the momentum distribution, the static and dynamic structure factors, and the density of excited states. The influence of finite temperature is discussed as well.

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  • Received 15 January 2008

DOI:https://doi.org/10.1103/PhysRevA.77.053609

©2008 American Physical Society

Authors & Affiliations

K. V. Krutitsky1, M. Thorwart2, R. Egger2, and R. Graham1

  • 1Fachbereich Physik der Universität Duisburg-Essen, Campus Duisburg, Lotharstrasse 1, 47048 Duisburg, Germany
  • 2Institut für Theoretische Physik, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany

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Issue

Vol. 77, Iss. 5 — May 2008

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