NATURE OF QUANTUM LOCALIZATION IN ATOMIC MOMENTUM-TRANSFER EXPERIMENTS

We demonstrate that the quantum localization (narrowed momentum distri butions) observed in the recent momentum transfer experiments may be a ssociated with the influence of classical phase space resonance struct ures on quantum Floquet states. By numerically investigating the evolu tion of initial distributions located in chaotic regions of the classi cal phase space, we argue that dynamical localization, seen, for examp le, in quantum kicked rotor models, is not the only possible explanati on of the observed localized momentum distributions.