Superconducting microwire detectors for single photon communications

Abstract

Superconducting microwire detectors (SMDs) provide the pinnacle of single photon counting in efficiency and sensitivity from optical to infrared wavelengths. Superconducting microwire detectors (SMDs) are a recent extension of the superconducting nanowire single photon detector (SNSPD) concept offering increased width of the superconducting wires up to the micron scale. This increase allows for devices to be fabricated by quick and cheap photolithography methods; bringing a new era of scalability to the superconducting wire sensors. This is coupled with the attraction that wider wires eases the creation of detectors with large active areas for improved optical coupling. The performance and deployment of SMDs is presented in this thesis. Investigations into the ability of large area, 1 micron and 2 micron wide wire NbTiN SMDs was performed to show their electrical and optical ability out to 1550 nm wavelength. Their relaxation time, kinetic inductance, critical current and timing jitter are characterised and discussed for future device considerations.Due to the SMD devices having very low dark counts in the region of optical sensitivity they are then deployed in proof-of-concept experiments for the detection array of the Breakthrough Starshot Initiative. Presented for these concept experiments is SMD characterisation at 450 nm wavelength along with single photon per pulse binary and PPM communications. Single photon signals are then rebuilt over time and the BER and PER is calculated for varying lengths of integration time.

Date of Award	Dec 2024
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	University of Glasgow
Supervisor	Robert hadfield (Supervisor) & Robert Bowman (Supervisor)