The antenna-coupled SIS quasiparticle array mixer

We report SIS mixing with Pb(In) junction arrays at 73.5 GHz. The array geometry and antenna coupling can be scaled to 300 GHz with existing technology. The measured SSB conversion loss is as good as 2.0±0.9 dB. This is marginally the best conversion result for a resistive mixer without image rejection yet published and agrees well with the quantum theory of mixing. We examine Josephson effect noise and thereby give a rough upper frequency limit for single-junction SIS mixers.