Resonance tunneling in a periodic time-dependent external field

Abstract

Resonance tunneling in the presence of external field W(x,t)=W(x)cos(ωt) is investigated within the framework of the classical perturbation theory. This approach is applied to a quantum-well structure in a superposition of a dc and sufficiently small ac (laser) field. Rigorous expressions for the shape of the tunneling spectra are obtained in a number of physically important cases. An ac field of the frequency ω large compared to the resonance width Γ is shown to split the resonance peak into a family of well-separated peaks with spacing between them equal to ω. In the limit of weak, slowly varying fields the form of the resonance peak is determined by the mean value of the time-dependent potential in the well only.