Hannover 2010 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 21: Poster I

Q 21.1: Poster

Tuesday, March 9, 2010, 16:00–19:00, Lichthof

Excitation spectrum of Bose-Einstein condensates in correlated disorder — •Christopher Gaul and Cord A. Müller — Physikalisches Institut, Universität Bayreuth, Deutschland

We consider a Bose-Einstein condensate in a speckle disorder potential. By a saddlepoint expansion of the Gross-Pitaevskii energy functional around the disordered groundstate [1], we compute the effective dispersion relation of Bogoliubov excitations perturbatively for weak disorder. Analytical predictions for the mean free path, the speed of sound and the density of states are derived for any dimension and the entire parameter space of healing length, disorder correlation length, and excitation wavelength. Notably, the speed of sound turns out to be reduced by correlated disorder [2]. We confirm our prediction in 1D by numerical simulations.

[1] Gaul and Müller, Europhys. Lett., 83, 10006 (2008)

[2] Gaul et al. PRA 80, 053620 (2009)