Ja. Stovneng et Ap. Jauho, NUMERICAL-STUDIES OF TUNNELING IN A NONHARMONIC TIME-DEPENDENT POTENTIAL, Physical review. B, Condensed matter, 47(16), 1993, pp. 10446-10451
Tunneling through time-dependent potentials is of relevance to a numbe
r of physical problems. Using a WKB analysis, Azbel' has recently stud
ied the effects of a nonharmonic time-dependent perturbation embedded
in an opaque potential barrier. He suggests the existence of three dif
ferent regimes for transmission in such systems: direct tunneling, act
ivation-assisted tunneling, and elevator resonant activation. We addre
ss the same problem with a numerical technique based on wave-packet si
mulations. Our numerical results are in qualitative agreement with the
picture of Azbel'. The outcome depends on the characteristic time T o
f the nonharmonic potential. There is a transition from direct tunneli
ng to the activation regime around a ''crossover'' value T(c) which is
determined by the Buttiker-Landauer time, the distance between the in
itial energy and the lowest resonant level, and the amplitude of the t
ime-dependent perturbation. The total transmission probability is stro
ngly enhanced when entering the activation regime.