Düsseldorf 2007 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 17: Quantengase (Bosonische Gitter I)

Q 17.4: Talk

Tuesday, March 20, 2007, 11:15–11:30, 6J

Kicked Bose-Hubbard systems and kicked tops – destruction and stimulation of tunneling — •Martin P. Strzys, Eva-Maria Graefe, and Hans-Jürgen Korsch — Fachbereich Physik, Technische Universität Kaiserslautern

In the two-mode approximation Bose-Einstein condensates (BEC) in a double-well potential can be described by a many particle Hamiltonian of Bose-Hubbard type. We focus on such a BEC whose interatomic interaction strength is modulated periodically with δ-kicks. This system in fact represents a model of a kicked top. The mean-field dynamics provide a rich mixed phase space with regular and chaotic regions. By increasing the kick-strength a bifurcation leads to the appearance of self-trapping states localized in regular islands. This self-trapping is also found for the many particle system, however in general suppressed by tunneling oscillations. We show that the tunneling time can be calculated from the quasi-energy splitting of the corresponding Floquet states. By varying the kick-strength these quasi-energy levels undergo both avoided and even real crossings. Using this fact stimulation or actually complete destruction of tunneling can be achieved for this many particle system.