SEMICLASSICAL ANALYSIS OF TUNNELING SPLITTINGS IN PERIODICALLY DRIVENQUANTUM-SYSTEMS

For periodically driven systems, quantum tunnelling between classical resonant stability islands in phase space separated by invariant KAM c urves or chaotic regions manifests itself by oscillatory motion of wav epackets centred on such an island, by mulitplet splittings of the qua sienergy spectrum, and by phase space localization of the quasienergy states on symmetry-related flux tubes. Qualitatively different types o f classical resonant island formation-due to discrete symmetries of th e system-and their quantum implications are analysed by a (uniform) se miclassical theory. The results are illustrated by a numerical study o f a driven non-harmonic oscillator.