Berlin 2008 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 15: Controlling Dirty Bosons: Disorder Effects on BECs

DY 15.2: Talk

Tuesday, February 26, 2008, 14:45–15:00, MA 001

Ultracold bosons in lattices with disorder created by "heavy" impurities — Konstantin V. Krutitsky¹, Michael Thorwart², Reinhold Egger², and •Robert Graham¹ — ¹Fachbereich Physik, Universität Duisburg-Essen, Lotharstraße 1, 47048 Duisburg, Germany — ²Institut für Theoretische Physik IV, Heinrich-Heine-Universität Düsseldorf, Germany

Quantum phases of ultracold bosons with repulsive interactions in optical lattices in the presence of 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 on-site energies which have a discrete probability distribution. The phase diagram at zero temperature is calculated using several methods like a strong-coupling expansion, an exact numerical diagonalization, a Bose-Fermi mapping, as well as two different versions of a mean-field theory.