Decoherence and the quantum-classical limit in the presence of chaos

We investigate how decoherence affects the short-time separation between quantum and classical dynamics for classically chaotic systems, within the framework of a specific model. For a wide range of parameters, the distance between the corresponding phase-space distributions depends on a single parameter x that relates an effective Planck constant "eff, the Lyapunov coefficient, and the diffusion constant. This distance peaks at a time that depends logarithmically on "eff, in agreement with previous estimations of the separation time for Hamiltonian systems. However, for x&1, the separation remains small, going down with "eff 2 , so the concept of separation time loses its meaning.