Superconducting detectors and their applications in terahertz astronomy

The terahertz frequency band (loosely defined as 0.1—10 THz) occupies approximately half of the photon energy in the universe and is particularly suitable for observing early distant objects, cold objects, and dusty objects. It also has very rich molecular, atomic and ion spectral lines, which are very important tracers for studying the dynamics of astronomical objects such as stars and planetary systems. In the past 40 years, low-temperature superconducting detector technology has rapidly developed, and has been widely applied in astronomy. A series of significant results have already been achieved, such as the imaging of black holes, the observation of the fine structure of protoplanetary disks, the characterization of water molecules in nearby universes, and the detection of the first molecule (HeH⁺) ever formed in the universe. In this paper we describe the recent research, application breakthroughs and future development trends of four kinds of terahertz superconducting detectors, namely, SIS mixers, HEB mixers, TES detectors, and KID detectors.