TUNNELING SPLITTINGS AND CHAOTIC TRANSPORT IN PERIODICALLY DRIVEN BISTABLE SYSTEMS

We study the crossover from coherent transport by tunneling to diffusi ve transport through classically chaotic phase-space regions, and the corresponding changes in the spectrum. The harmonically driven quartic double well is used as a working model and treated numerically in the framework of the Floquet formalism. We find a transition from exponen tially small tunnel splittings to level separations of the order of th e mean level distance, when the corresponding classical dynamics becom es dominated by chaotic diffusion.