Dynamical origin of decoherence in classically chaotic systems

The decay of the overlap between a wave packet evolved with a Hamiltonian H and the same state evolved with H + Sigma serves as a measure of the decoh erence time tau(phi). Recent experimental and analytical evidence on classi cally chaotic systems suggest that, under certain conditions, tau(phi) depe nds on H but not on Sigma. By solving numerically a Hamiltonian model we fi nd evidence of that property provided that the system shows a Wigner-Dyson spectrum (which defines quantum chaos) and the perturbation exceeds a cryti cal value defined by the parametric correlations of the spectra. (C) 2000 E lsevier Science B.V. All rights reserved.