Performance of SNSPDs at varying cooling conditions

For superconducting nanowire single-photon detectors (SNSPD), there is a wide market of applications, like correlation spectroscopy or quantum cryptography, that profits from detectors with large speed and high detection efficiency. SNSPDs made of ultra-thin NbN films, patterned as a meander nanowire with a width in the range of 100 nm, offer a great change for the future to cover these specifications. NbN has been proven to be an excellent material for the development of SNSPD. In context of high detection efficiency, a very low dark count rate is needed to satisfy the demands of several applications. Former studies show, that there is a certain relation between the detection mechanism and the dark counts [1], [2]. The origin of dark counts is due to thermal fluctuations in the meander structure of a SNSPD. To reduce this dark count rate, an investigation of influence of cooling conditions on the dark counts is necessary.