Superconducting nanowire single-photon detector with ultralow dark count rate using cold optical filters

摘要

We report the fabrication of a superconducting nanowire single-photondetector (SSPD or SNSPD) with an ultralow dark count rate. By introducingoptical band-pass filters at the input of the SSPD and cooling the filters at 3K, the dark count rate is reduced to less than 1/100 at low bias. An SSPD with0.1 cps dark count rate and 5.6% system detection efficiency at 1550 nmwavelength is obtained. We show that a quantum key distribution (QKD) over 300km of fiber is possible based on a numerical calculation assuming adifferential phase shift QKD protocol implemented with our SSPDs.