Overview of single photon detection technologies

Single photon detectors are one of the essential tools connecting the photonic and electronic domains at the quantum level. A plethora of single photon detector technologies and their acronyms available today - PMT, IPD, SPAD, SNSPD, MKID, RULLE, NFAD, TCB, DAPD, TES, and many others - primarily because all have significant gaps to “ideal” performance and practical usability. Some do approach ideal performance in a specific metric such as detection efficiency or dark count rate, and there is promising new progress in new material systems and new understandings of the semiconductor avalanche gain process.