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Q: Fachverband Quantenoptik und Photonik
Q 47: Quantengase: Gitter und Tunneln I
Q 47.5: Talk
Thursday, March 5, 2009, 15:00–15:15, Audi-A
Stability of Bloch oscillations in certain interacting BECs — •Christopher Gaul1, Cord Axel Müller1, Rodrigo de Lima2, Elena Díaz García2, and Francisco Dominguez-Adame2 — 1Physikalisches Institut, Universität Bayreuth, Deutschland — 2Universidad Complutense de Madrid, España
We consider Bloch oscillations of a BEC in an optical lattice, using a tight binding model in the mean-field regime. Single-particle Bloch oscillations are very sensitive to any dephasing effect like on-site disorder or particle-particle interaction. Here we investigate the influence of a time-dependent repulsive interaction with zero time-average. In this driven system, we identify two distinct mechanisms for the collapse of Bloch oscillations: One mechanism acts directly on the width of the wave packet, resulting in an immediate decay of the oscillation. The other mechanism is more subtle and consists in an instability to perturbations on a short length scale compared to the width of the wave packet. Here it takes a long time for the perturbations to grow, which suddenly destroy the Bloch oscillation.