Darmstadt 2008 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 37: Quantengase (Wechselwirkungseffekte I)

Q 37.4: Vortrag

Donnerstag, 13. März 2008, 11:45–12:00, 1C

Coherent backscattering of Bose-Einstein condensates in two dimensional disorder potentials — •Michael Hartung, Klaus Richter, and Peter Schlagheck — Institute for Theoretical Physics, University of Regensburg, Germany

The rapid progress in the experimental techniques for Bose-Einstein condensates permits detailed studies of mesoscopic transport dynamics of interacting matter waves with rather high accuracy and high flexibility in the control of parameters. We particularly focus on quasi-stationary transport processes of Bose-Einstein condensates through two dimensional disorder potentials by integrating the time-dependent Gross-Pitaevskii equation.
In the limit of vanishing atom-atom interaction we observe coherent backscattering, which leads to a sharp cone, centered around the backward direction, in the angle resolved density of the scattered condensate. This is a characteristic signature of weak localization and arises due to the constructive interference of semiclassical scattering paths with their time reversed counterparts. This coherent backscattering peak is transformed into a pronounced dip for weak repulsive interaction, and eventually vanishes for strong interaction. In this latter regime we find intrinsic time-dependent behavior of the condensate wavefunction, which effectively suppresses the interference phenomena that give rise to the coherent backscattering signal.