Аннотация:
The semiclassical long-time limit of free evolution of quantum wave packets on the
torus is under consideration. Despite the simplicity of this system, there are still
open questions concerning the detailed description of the evolution on time scales
beyond the Ehrenfest time. One of the approaches is based on the limiting Wigner
or Husimi distributions of time-evolved wave packets as the Planck constant tends
to zero and time tends to infinity. We derive explicit expressions for semiclassical
measures corresponding to all time scales and the corresponding stages of evolution:
classical-like motion, spreading of the wave packet, and its revivals.