Statistics of quasi-energy separations in chaotic systems

Abstract
The distribution of the quasi-energy separations for the periodically kicked quantum rotor is calculated. This distribution is different from that associated with chaotic systems whose wave functions are extended throughout the system. Rather it agrees with the statistics expected for random band-diagonal Hamiltonians, which describe quantum motion in a disordered medium, where the wave functions are localized. Novel statistical measures based on this localization are devised and applied.