Control of dissipative tunneling dynamics by continuous wave electromagnetic fields: Localization and large-amplitude coherent motion

The dynamics of a dissipative two-level system in a monochromatic field is studied numerically using an iterative path integral scheme that is based on the finite memory range of dissipative influence functionals. The focus of the paper is on the interplay between dissipation and field-induced localization or coherent tunneling. In accord with recent predictions based on approximate treatments, we find that weak dissipation can stabilize the localized state while strong dissipation destroys it. We also demonstrate the possibility of inducing and maintaining large-amplitude coherent oscillations by exploiting the phenomenon of quantum stochastic resonance. (c) 1995 The American Physical Society