QUANTUM LOCALIZATION, CHAOS AND NONLINEAR-INTERACTIONS

The results of analytical and numerical investigations of destruction of quantum localization of chaos by a nonlinear interaction are presented. Two different cases are considered. One is the one-particle case which corresponds to nonlinear wave propagation in disordered media. Another case corresponds to the destruction of localization by multi-particle self-consistent interaction at small but finite particle density. It is shown that delocalization and unlimited spreading over the lattice takes place above a critical value of nonlinear interaction. The spreading can be described by anomalous diffusion with the exponent smaller than in the diffusive case.