Numerical studies of tunneling in a nonharmonic time-dependent potential
  Azbel' has recently carried out a WKB-analysis of the effects of a nonharmonic time-dependent perturbation embedded in an opaque potential barrier. He suggests the existence of three different transmission regimes: direct tunneling, activation assisted tunneling, and elevator resonant activation. We address the same problem with a numerical technique, and find qualitative agreement with Azbel's picture. 
J. A. St{\o}vneng and A.-P. Jauho