Development of Superconducting Receiver Technologies Supporting Radio Astronomy

The development of superconductor-insulator-superconductor (SIS) receivers at the National Astronomical Observatory of Japan (NAOJ) will be presented. NAOJ has participated in an international project, the Atacama Large Millimeter/Submillimeter Array (AL-MA), which is the most sensitive ground-based radio-astronomical telescope. During the construction phase of ALMA, NAOJ has developed and manufactured Band 4 (125–163 GHz), Band 8 (385–500 GHz), and Band 10 (787–950 GHz) SIS receivers. After the construction, NAOJ has been developing the next generation SIS receiver technologies for AL-MA enhancement such as wideband and multibeam SIS receivers according to top-level science requirements. More recently, we also started to develop SIS mixers to be used in the Black Hole Explorer (BHEX), which is a concept space very long baseline interferometry (VLBI) that will extend the network of ground-based radio telescopes into space and will also be presented.