Optical Analogs for Multilevel Quantum Systems

Abstract

In Sect. 2.12, we considered a type II semiconductor heterostructure, in which the quantum wavefunction is a two-component vector, with one component describing the envelope wavefunction in the conduction band and the other describing the envelope wavefunction in the valence band. It was shown that such an object is equivalent to a succession of directional couplers, where the electromagnetic field in each of these couplers is the sum of the fields in the two waveguides. Section 2.12 focused on tunneling phenomena, i.e., the process of traversing a succession of wells and barriers for wave propagation at a constant energy. A semiconductor in which the coupling between different electron bands must be specifically taken into account is an example of a multilevel quantum system. However, whether quantum or classical, tunneling is only one and certainly not the most spectacular phenomenon in multilevel systems.