Abstract

The desire to minimize the response time of tunneling devices has led to renewed interest in the unresolved fundamental question "How much time, on average, does an incident electron that is ultimately transmitted spend inside a one-dimensional potential barrier?" In addition to this transmission time ⊤_t ·,there are two other times of interest: the reflection time ⊤_r for electrons that are ultimately reflected and the dwell time T_D, which is the average time spent inside the barrier regardless of the ultimate fate of the incident particle. An exact expression for T_D and the time-modulated barrier, Feynman path, Larmor clock, and wave-packet evolution approaches for calculating ⊤_t and ⊤_r arc discussed. It is argued that none of these approaches is completely satisfactory because they all lead to transmission and reflection times that either are complex or, if real, do not satisfy: all of a few reasonable (but not universally accepted) criteria, such as consistency with the exact expression for the dwell time.

© 1991 Optical Society of America