LIGHT-INDUCED ELECTRON-TRANSFER COUNTER TO AN ELECTRIC-FIELD FORCE IN AN ASYMMETRIC DOUBLE QUANTUM-WELL

Electron transfer counter to an electric-field force is predicted for an asymmetrical double quantum well subjected to a dc bias in response to optical (far IR) excitation of an intersubband electronic transition. This transfer exhibits a resonance enhancement when the bias electric field aligns the excited levels in the wide and narrow wells. The transfer effect is driven by the quantum-mechanical delocalization caused by the coherent resonant tunneling which prevails over the electric force. The effect brings about a photoinduced increase of the potential difference at the double well and a transient electric current opposite to the direction favored by the bias.