ANOMALOUS DIFFUSION IN 2-DIMENSIONAL ANDERSON-LOCALIZATION DYNAMICS

Extensive numerical simulations of wave packets and pulses in two-dime nsional (2D) random systems exhibit a subdiffusion at intermediate tim es, shown to be linked to the fractal structure of 2D eigenstates. The mean-square pulse width [Absolute value of r2] scales as t2nu, with 0 less-than-or-equal-to nu less-than-or-equal-to 1/2 being a continuous function of the disorder strength. Good agreement is found between nu merical values of nu and weak-localization predictions. At very long t imes, the subdiffusive regime crosses over to localization with long p ower-law asymptotics.