LOCALIZATION IN DISCONTINUOUS QUANTUM-SYSTEMS

Classical and quantum properties of a discontinuous perturbed twist ma p are investigated Different classical diffusive regimes, quasilinear and slow, respectively, are observed. The regime of slow classical dif fusion gives rise to two distinct quantal regimes, one marked by dynam ical localization, the other by quasi-integrable localization due to c lassical cantori. In both cases the resulting quantum stationary distr ibutions ate algebraically localized.