Two level systems driven by a stochastic perturbation

Here we consider a two level system driven by an external harmonic field whose amplitude is perturbed by a white noise term. In the limit of small splitting, dynamical localization, i.e. coherent destruction of tunneling, is proved for times of the order of 1/epsilon, where epsilon is the two-level splitting. The same type of localization is proved if the driving field is simply the white noise.