Hannover 2013 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 18: Quantum gases: Mixtures, spinor gases, disorder effects
Q 18.2: Talk
Monday, March 18, 2013, 16:45–17:00, E 001
Quantum depletion of Bose-Einstein condensates in random lattice potentials — •Christopher Gaul1,2 and Cord A. Müller3 — 1GISC, Departamento de Física de Materiales, Universidad Complutense, E-28040 Madrid, Spain — 2CEI Campus Moncloa, UCM-UPM, Madrid — 3Centre for Quantum Technologies, National University of Singapore, Singapore 117543, Singapore
We develop an inhomogeneous Bogoliubov theory for bosons on a tight-binding lattice [1]. In the first step, this consists in determining the condensate deformation caused by a weak external disorder potential. Then, the momentum distribution of quantum fluctuations around the deformed ground state is obtained via weak-disorder perturbation theory, and finally the resulting quantum depletion is calculated. As in the continuous case [2], the depletion due to the external potential, or potential depletion for short, is a small correction to the homogeneous depletion, validating our inhomogeneous Bogoliubov theory. Scattering due to disorder is strongest when the energy shell touches the Brillouin zone (BZ) edges. In the continuous limit, i.e., far away from the edges of the BZ, we reproduce previous results [2].
[1] arXiv:1209.5446. [2] New J. Phys., 14, 075025 (2012).