Low timing jitter detector for gigahertz quantum key distribution

A superconducting single-photon detector based on a niobium nitride nanowire is demonstrated in an optical-fibre-based quantum key distribution test bed operating at a clock rate of 3.3 GHz and a transmission wavelength of 850 nm. The low jitter of the detector leads to significant reduction in estimated quantum bit error rate and a resultant improvement in secrecy efficiency compared to previous estimates made by use of silicon single-photon avalanche detectors.