Ultimate low system dark count rate for superconducting nanowire single-photon detector

TL;DR

This paper demonstrates a significant reduction in the dark count rate of superconducting nanowire single-photon detectors by using optical filtering and cooling, achieving record low DCR levels.

Contribution

The authors introduce a bulk optical band-pass filter and cooling method that suppresses dark counts by over three orders of magnitude, setting new low DCR benchmarks.

Findings

DCR reduced to 0.001 Hz with a 20 nm bandwidth filter

Further reduction to 0.0001 Hz with 100 GHz bandwidth filtering

System detection efficiency remains at 2.3%

Abstract

The dark count rate (DCR) is a key parameter of single-photon detectors. By introducing a bulk optical band-pass filter mounted on a fiber-to-fiber optical bench cooled at 3 K and blocking down to 5 micrometer, we suppressed the DCR of a superconducting nanowire single-photon detector by more than three orders of magnitude. The DCR is limited by the blackbody radiation through a signal passband of 20 nm bandwidth. The figure of merit, system detection efficiency, and DCR were 2.7 x 10^11, 2.3 %, and 0.001 Hz, respectively. Narrowing the bandwidth to 100 GHz suppresses the DCR to 0.0001 Hz and the figure of merit increases to 1.8 x 10^12.