Quantum reflection time and the Goos-H\"anchen effect

Abstract

We explore the analogy between following the motion of a reflected wave packet, and a quantum measurement of the spatial delay imposed on the particle by the scattering potential. It is shown that converting such delays into temporal durations can lead to "negative times", and best be avoided. It is also demonstrated that a "soft" potential can be replaced by superposition of hard walls. This representation is used for calculating the Goos-H\"anchen shift of a Gaussian beam incident on a potential step or a barrier at an oblique angle.