Effects of interactions on the dynamics of driven cold atoms

The quantum fidelity was introduced by Peres to study some fingerprints of classically chaotic behavior in the quantum dynamics of the corresponding systems. In the present paper the signatures of classical dynamics near elliptic points and of interactions between particles are characterized for kicked systems. In particular, the period of the fidelity resulting of the interactions is found using analytical and numerical calculations. A mechanism leading to the oscillations with the intermediate period is proposed. It is of a semiclassical origin and results of the interplay between the oscillations of the width of the wave packets and the rotation of their center around the elliptic fixed point.