CHAOS AND AVOIDED LEVEL-CROSSINGS

The influence of chaos on tunneling in the quantum phase space of the harmonically driven pendulum is studied herein. We analyze the avoided level crossing between a quasienergy state associated with the chaotic part of the phase space and a member of the nearly degenerate doublet localized on the symmetric Kolmogorov-Arnold-Moser (KAM) islands. As a result of the interaction the quasienergy states ''exchange'' their structure. The initially chaotic state evolves into the regular one and vice versa. This interchange significantly affects dynamical tunneling of wave packets centered on the KAM islands.