We demonstrate for various systems that the variance of a wave packet $M\left(t\right)\mathrm{}\propto t^{\nu },$ can show a superballistic increase with $2<\mathrm{}\nu <~3,$ for parametrically large time intervals. A model is constructed that explains this phenomenon and its predictions are verified numerically for various disordered and quasiperiodic systems.

• Received 10 January 2001

DOI:https://doi.org/10.1103/PhysRevE.64.012301