QUANTUM DOTS AS A TUNABLE MICROWAVE QUANTUM DETECTOR

In arrays of field-effect confined quantum dots, we observe a novel resonant photovoltaic response to microwave and far-infrared radiation. A maximum photosignal of 5 muV at an incoming microwave power of less than 1 mW is detected when the frequency of the radiation matches the resonance condition of the electrons confined in the quantum dots. The response frequency is tunable by means of the gate voltage or an external magnetic field. This observation leads to an efficient quantum detector working up to temperatures of about T = 6 K and to a novel spectroscopic tool for the investigations of low-dimensional electronic systems.