ZENER TUNNELING IN SYSTEMS WITHOUT LEVEL-CROSSING

We compare the standard Zener tunneling problem with one in which the unperturbed states do not intersect. We find that even when their adiabatic energy spectra are identical, the two cases have dramatically different asymptotic tunneling probabilities. The time of Zener tunneling, a measure of the duration of the transition, is also different for the two. The latter is determined by calculating the transition probability as a function of time, for both the sudden and adiabatic limits. We also develop analytic asymptotic expansions for the tunneling probability for these limits. The results are discussed in terms suitable for comparison with experiment. © 1990 The American Physical Society.