Single-photon metrology with superconducting nanowire single-photon detectors

Abstract

Single-photon sources and detectors underpin the development of quantum photonic technologies. This thesis presents research into single-photon devices with a focus on telecom wavelengths. A two-channel superconducting nanowire single-photon detector (SNSPD) system was constructed and characterised. It provides free-running single-photon detection at telecom wavelengths with low dark counts and timing jitter below 90 ps FWHM. The system detection e ciency at 1310 nm is 1 % with a 1 kHz dark count rate, which was competitive when the SNSPD was built in 2009. In this work, the low timing jitter of the SNSPD was bene cial to the development of a two-photon interference experiment. Experiments were carried out with single-photon sources based on self-assembled InAs/GaAs quantum dots in micropillar cavities. Preliminary measurements of the second-order correlation function gave g(²)(τ=0) = 0.12 ± 0.04 with above-band excitation and g(²)( τ = 0) = 0:07 ± 0:05 with near-resonant excitation. These values agree with recent papers reporting improved measurements with near-resonant excitation. Irreparable damage to the sample prevented further investigation. This thesis also presents the design, construction and characterisation of a highresolution single-photon spectrometer for telecom wavelengths. The instrument, a scanning Fabry-Perot interferometer, was optimised for the characterisation of quantum photonic sources. It has a spectral resolution of 550 MHz and a free spectral range of (119.0 ± 0.4) GHz.