Tunneling control by high-frequency driving

The second-order perturbation theory in the framework of the Kramers-Henneb erger oscillating frame representation of the Hamiltonian [H. A. Kramers, Q uantum Mechanics (North-Holland, Amsterdam, 1956); W. C. Henneberger, Phys. Rev. Lett. 21, 838 (1968)] is used to study the tunneling process in a per iodically driven double-well potential. The eigenstates of the Floquet Hami ltonian are efficiently approximated when a field frequency is larger than a classical frequency of the time-averaged Hamiltonian. The conditions for coherent enhancement and suppression of tunneling are obtained when the sta ndard perturbation theory fails. It is shown that the enhancement and suppr ession of tunneling is due to field-induced coupling between states of a on e-period averaged effective potential. [S1050-2947(99)00103-1].