Decoherence for classically chaotic quantum maps

PABLO BIANUCCHI; JUAN PABLO PAZ; MARCOS SARACENO

PHYSICAL REVIEW E - STATISTICAL PHYSICS, PLASMAS, FLUIDS AND RELATED INTERDISCIPLINARY TOPICS

APS

Año: 2002 vol. 65 p. 62226 - 62236

1063-651X

We study the behavior of an open quantum system, with an N-dimensional space of states, whose density matrix evolves according to a nonunitary map defined in two steps: A unitary step, where the system evolves with an evolution operator obtained by quantizing a classically chaotic map ~baker?s map and Harper?s map are the two examples we consider!. A nonunitary step where the evolution operator for the density matrix mimics the effect of diffusion in the semiclassical ~large N) limit. The process of decoherence and the transition from quantum to classical behavior are analyzed in detail by means of numerical and analytic tools. The existence of a regime where the entropy grows with a rate that is independent of the strength of the diffusion coefficient is demonstrated. The nature of the processes that determine the production of entropy is analyzed.