Local Larmor clock approach to the escape time

The escape of an electron from a localized state in a quantum well with one or several surrounding barriers is analyzed using the local Larmor clock approach. We show that two time scales can be involved in the escape time problem, such as in the case of a scattering configuration. The particular example of a potential well with a hard wall condition on one side, i.e. escaping through only one open channel, is investigated, and the two time components are calculated analytically. One of the time components is shown to coincide with the lifetime expression obtained with a different approach, in the case of an opaque barrier, at an energy close to the bound level in the well.