Semiclassical evolution of quantum wave packets on the torus beyond the Ehrenfest time in terms of Husimi distributions

TL;DR

This paper investigates the long-time semiclassical evolution of quantum wave packets on a torus, deriving explicit measures for different stages of evolution and discussing the approach's limitations and potential generalizations.

Contribution

It provides explicit formulas for semiclassical measures of wave packet evolution on the torus across all time scales, extending understanding beyond the Ehrenfest time.

Findings

Derived explicit expressions for semiclassical measures at various evolution stages

Identified limitations of semiclassical measures approach

Suggested possible generalizations for better description of long-time dynamics

Abstract

The semiclassical long-time limit of free evolution of quantum wave packets on the torus is under consideration. Despite of 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. Also we discuss limitations of the approach based on semiclassical measures and suggest its generalization.