Classical-field-induced anomalies in tunneling dynamics of glasses

Pronounced anomalies are predicted in the absorption and scattering of electromagnetic and acoustic waves by tunneling particles in local double-well (or multiwell) potentials when an external classical field is applied, ``dressing'' the particles by its numerous excitations. The latter phenomenon, which in particular reflects the previously discovered ``coherent destruction of tunneling,'' gives rise to oscillations of the absorption and scattering coefficients when the classical-field frequency or amplitude is varied, and to their vanishing at certain discrete values of the amplitude-to-frequency ratio. This phenomenon has to occur in some types of defects in crystals, particularly in glasses. For the latter, the dynamical properties at sufficiently low temperatures and frequencies are expected to change basically due to the external classical field.