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Q: Fachverband Quantenoptik und Photonik
Q 48: Quantum Gases: Effects of Interactions
Q 48.2: Vortrag
Donnerstag, 17. März 2011, 10:45–11:00, SCH 251
Dipolar Bose-Einstein Condensates with Weak Disorder — •Christian Krumnow1 and Axel Pelster2 — 1Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany — 2Fachbereich Physik, Universität Duisburg-Essen, Lotharstrasse 1, 47048 Duisburg, Germany
We consider a homogeneous dipolar Bose-Einstein condensate in the presence of weak quenched disorder within mean-field theory. By solving perturbatively at first the underlying Gross-Pitaevskii equation and performing then disorder ensemble averages, we derive the disorder-induced depletion of the condensate density. Furthermore, we obtain the result that the anisotropy of the two-particle interaction is passed on to both the superfluid density and the sound velocity at zero temperature. For a small dipolar interaction the superfluid depletion for a motion parallel or perpendicular to the dipoles is larger than the condensate depletion in accordance with the Huang-Meng theory of Bose-Einstein condensates with pure contact interaction [1]. For a sufficiently strong dipolar interaction, however, the superfluid depletion for a motion parallel to the dipoles becomes smaller than the condensate depletion. This astonishing finding supports that the tiny Bose-Einstein condensates, which are localized in the respective minima of the random potential, have a finite localization time [2].
[1] K. Huang and H. F. Meng, Phys. Rev. Lett. 69, 644 (1992).
[2] R. Graham and A. Pelster, Int. J. Bif. Chaos 19, 2745 (2009).