FAR-INFRARED PHOTON-INDUCED CURRENT IN A QUANTUM POINT-CONTACT

Motivated by the recently developed theory of photon-assisted quantum transport, we have studied transport properties of an antenna-coupled quantum point contract under coherent far-infrared (285 GHz) radiation . A pronounced photon-induced drain/source current is observed. The am plitude of the photon-induced current is about 10% of that correspondi ng to a quantized conductance step, and it oscillates with the gate vo ltage. Our analysis suggests that the observed photon-induced current is mainly due to heating of the electron gas in the source and drain ( a bolometric effect) rather than photon-assisted quantum transport. Fu ture improvement of the device parameters to enhance the effect of pho ton-assisted transport will be discussed.