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

TL;DR

This paper presents a superconducting nanowire single-photon detector with an ultralow dark count rate achieved by cooling optical filters, enabling long-distance quantum key distribution over 300 km of fiber.

Contribution

Introduction of a novel SSPD design with ultralow dark counts using cooled optical filters, enhancing quantum communication capabilities.

Findings

Dark count rate reduced to less than 1/100 with cooled filters

Achieved 0.1 cps dark count rate and 5.6% efficiency at 1550 nm

Quantum key distribution over 300 km of fiber is feasible with these detectors

Abstract

We report the fabrication of a superconducting nanowire single-photon detector (SSPD or SNSPD) with an ultralow dark count rate. By introducing optical band-pass filters at the input of the SSPD and cooling the filters at 3 K, the dark count rate is reduced to less than 1/100 at low bias. An SSPD with 0.1 cps dark count rate and 5.6% system detection efficiency at 1550 nm wavelength is obtained. We show that a quantum key distribution (QKD) over 300 km of fiber is possible based on a numerical calculation assuming a differential phase shift QKD protocol implemented with our SSPDs.