On photon-assisted tunneling in quantum well structures

The real space transfer of electrons between quantum wells is accompanied by radiation. Such radiation, the optical analog of shot noise, is first estimated using classical electrodynamics. Next, a fully quantum mechanical treatment is presented and gives the same result as the semi-classical treatment. The inverse process, photon-assisted tunneling, is also investigated, and compared to the sequential resonant tunneling process. Sequential resonant tunneling dominates when the energy of the resonant state is exactly matched to the initial state energy. Otherwise, the two processes are of comparable magnitude, and add coherently to give the overall transition matrix element.