title: Non-instanton tunneling: semiclassical and quantum interpretations.
abstract: Tunneling essentially different from instanton-type tunneling, say noninstanton tunneling, is studied from both semiclassical and quantum viewpoints. Taking a periodically perturbed rounded-off step potential for which the instanton-type tunneling is substantially prohibited, we analyze change of the tunneling probability with change of the perturbation frequency based on the stable-unstable manifold-guided tunneling (SUMGT) theory, which we have recently introduced. In the large and small limits of the frequency, the tunneling rate rapidly decays, but it is markedly enhanced in an intermediate range. We will also make a quantum interpretation of the noninstanton tunneling by using an exactly solvable model--a periodically perturbed right-angled step potential. Analysis with this model shows that SUMGT is considered as a sort of photoassisted tunneling through a large energy gap induced with absorbing a huge number quanta, which is completely different from the instanton-type tunneling. Both approaches from the semiclassical and quantum viewpoints complement each other to cause a better understanding of noninstanton tunneling.
authors.affiliation: The Physics Laboratories, Kyushu Institute of Technology, Kawazu 680-4, Iizuka 820-8502, Japan.
authors.forename: Kin'ya
authors.initials: K
authors.lastname: Takahashi
authors.forename: Kensuke S
authors.initials: KS
authors.lastname: Ikeda