Development of superconducting mixers for THz astronomy

Abstract

The terahertz (THz) regime, loosely defined as 0.1–10 THz, is the last frequency window to be fully explored in astronomy. In particular, it is a regime in which there are rich molecular rotation lines and atomic fine structure lines. They are very important tracers for studying the dynamics of astronomical objects such as stars and planetary systems. Observing those spectral lines usually makes use of coherent detectors (i.e., heterodyne mixers). With sensitivity approaching the quantum limit, superconducting mixers have become the coherent detector of choice in THz astronomy. In this paper we mainly introduce the superconducting mixers developed at Purple Mountain Observatory and those for international collaborative projects.