Photon Induced Tunneling Oscillations in a Double Quantum Well

Abstract

Tunneling oscillations induced in a double quantum well by a monochromatic electromagnetic wave incident perpendicularly to the plane of the well, and polarized along the direction of its growth, are treated. For the wave frequency in proximity to the energy difference between two states of opposite symmetry, a periodic energy exchange between the wave and a carrier which moves from one energy state to the other is established. When the carrier starts from the low energy level it borrows energy from the wave until it reaches the higher energy state. On its way the carrier performs current oscillations that cease whenever it reaches an eigenstate. Similarly, oscillation is required during the carrier's motion from the high to the low energy state for the photon emission in order that the radiation gets back the energy already given to the carrier. Thus an accelerating charge not only radiates, but also absorbs wave energy. When there prevails a considerable population difference between the two levels the possibility of quantum beat exits.