Far-infrared photon-induced current in a quantum point contact

Abstract
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 amplitude of the photon-induced current is about 10% of that corresponding to a quantized conductance step, and it oscillates with the gate voltage. 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. Future improvement of the device parameters to enhance the effect of photon-assisted transport will be discussed.

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