Collapse of the wave packet and chaos in a model with classical and quantum degrees of freedom.

Abstract

A simple model having classical and quantum degrees of freedom is studied. In the presence of dissipation, and in the limit of strong coupling between classical and quantum variables and large separation between the corresponding time scales, collapse of the wave packet is demonstrated. The collapse appears as a phase transition below a certain critical temperature. When a sufficiently strong external ac magnetic field is added, the system becomes chaotic. Possible experimental realizations are discussed.