Kinetics of Intersubband Optical Excitation and Photoinduced Electron Transfer inan Asymmetric Double Quantum Well

摘要

Optical excitation of electrons in an asymmetric double quantum well istheoretically examined. The well is biased to align the excited levels and permit resonant electron tunneling. Emphasis is made on the photoinduced transfer of electrons counter to the bias electric field force. Systems with a weak polarization relaxation (dephasing), are studied using the conventional technique of the Schrodinger equation. A density matrix approach is developed to describe optical excitations in the presence of an arbitrary dephasing. Quantum beats, which follow a short-pulse excitation of the double well, are shown to crucially depend on the dephasing. The excitation profiles obtained for cases of different dephasing reveal the full range of tunneling coupling between the wells from completely coherent to incoherent (stepwise).