Detection of coherent terahertz radiation from a HTS Josephson junction by a semiconductor quantum dot detector

We examine the application of Josephson radiation emitters to spectral calibration of singlephoton-resolving detectors. Josephson junctions were patterned in a YBCO film on a bi-crystal sapphire substrate and were voltage controlled to generate radiation in the frequency range of 0.051 THz. The detector used in this work consisted of a gate-defined quantum dot photon-to-charge transducer coupled to a single-electron transistor. Both the emitter and the detector were equipped with matching on-chip wide band antenna. The combination of a tuneable emitter and detector allowed us to determine the efficacy of the YBCO emitter and also to analyse the elementary processes involved in the detection.