CONTROL OF DYNAMICAL TUNNELING IN A BICHROMATICALLY DRIVEN PENDULUM

We demonstrate that the avoided level crossing between the Floquet state associated with the chaotic part of classical phase space and a member of the quasidegenerate doublet may lead to the enhancement of the doublet splitting by several orders of magnitude. As a result of this interaction the two-level tunneling dynamics is replaced by the more intricate dynamics involving three states. It is shown that three-level tunneling is much more robust against symmetry breaking perturbations than is ordinary tunneling. © 1994 The American Physical Society.