SPATIAL STRUCTURE IN MODE POPULATION INDUCED BY COHERENT PUMPING IN ABALLISTIC QUANTUM CHANNEL

We predict a spatially varying mode population to appear in a ballisti c quantum channel formed in the two-dimensional electron gas of a gate d GaAs/AlGaAs heterostructure due to pumping by a THz held. If a reson ant coupling between two modes is suddenly switched on at the entrance , Rabi oscillations in the mode population will arise. We propose to u se an array of gates in order to simulate a moving quantum point conta ct for detecting mode population oscillations since they discriminate between different modes. By consecutively activating them we expect to see both photovoltaic effects and photoconductive effects that can ea sily be distinguished from noise. (C) 1997 American Institute of Physi cs.