Superconducting single-photon detector with a system efficiency of 93% operated in a 2.4 K space-application-compatible cryocooler

We report herein the development of a superconducting nanowire single-photon detector (SNSPD) that uses a hybrid cryocooler compatible with space applications. The hybrid cryocooler incorporates a two-stage high-frequency pulse-tube cryocooler and a Joule–Thomson loop, which produces a minimum temperature of 2.2 K. The SNSPD with the structure of sandwiched nanowires integrated in the cryocooler shows a maximum detection efficiency of 93% at...