Kicked Bose-Hubbard systems and kicked tops -- destruction and stimulation of tunneling
Martin P. Strzys, Eva-Maria Graefe, H. J. Korsch
Abstract
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 $\\delta$-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. Therefore stimulation or actually complete destruction of tunneling is observed for this many particle system.