Generic Regularities in Quasienergy Spectra and Free Quantum Dynamics Independently of Chaos Strength

摘要

Generic and significant regularities are shown to occur in the quasienergyspectra of the generalized quantum kicked particle for arbitrary quasimomentum,a quantity most relevant in atom-optics experimental realizations of thisparadigmatic nonintegrable system. The spectral regularities are basicallydifferent from the usual ones associated with ordered regions in a mixed phasespace, since they are \emph{completely independent} of the chaos strength.Their origin are free-motion features unaffected by the nonintegrability. Thegeneric regularities are \emph{dense} subspectra, each being either a regularlevel sequence with approximately a Poisson level-spacing distribution or aladder of equally-spaced levels. The quantum dynamics associated with eachregular subspectrum is essentially \emph{free} for \emph{arbitrarily strong}chaos.