MODULATED BARRIER APPROACH TO THE INTERACTION TIME IN TUNNELING FOR ARBITRARY POTENTIALS

The time that a transmitted particle interacts with a tunneling barrier is evaluated in one of the principal existing approaches by considering a small oscillatory perturbation added to the static barrier. The modulation frequency, at which a serious deviation from quasistatic behavior appears, is indicative of the traversal time. This approach is extended here, to a long region including the barrier, and utilizing a modulation potential which is spatially uniform throughout this region, except in the incident region ahead of the actual barrier, where it is made sufficiently smooth to avoid reflections. The resulting traversal time is hBAR\partial derivative ln(partial derivative t/dE)partial derivative E\ where the complex transmission coefficient t(E) is defined as the ratio of the wave function at the far end to that of the incident wave, at the point of incidence. This answer applies to arbitrary potentials and to all energies, including both propagation and tunneling in a single framework. This result is closely related to, but not identical to, that obtained by another earlier approach in which the potential is fixed, but the incident amplitude is modulated.