Research Fellows Directory
Professor Robert Hadfield PhD, URF
University of Glasgow
One of Einstein’s key contributions to modern science was to recognize that light is fundamentally composed of discrete packets of energy known as photons. A single photon detector is an extremely sensitive device capable of counting these individual quantum objects – at low light intensities the arrival of photons can be distinguished as clearly as the first patter of raindrops on a tin roof. Lower energy (infrared) photons are less strongly adsorbed and scattered by typical transmission media (the atmosphere, optical fibre or even living tissue) than photons at visible wavelengths. Hence infrared single photon detectors are a key enabling technology for a host of scientific applications, ranging from the ultimate in secure communications (quantum cryptography), to new methods of medical imaging. Serious problems are encountered when attempting single photon counting with conventional semiconductor-based detectors in the infrared. This technological gap represents a significant obstacle for researchers across a range of fields.
My research programme, based at Heriot-Watt University in Edinburgh, focusses on a new type of single-photon detector, based on a superconducting nanowire. This detector offers single-photon sensitivity from visible to mid infrared wavelengths with exquisite timing resolution and excellent signal-to-noise. I have developed state-of-the art facilities for characterizing these devices and for integrating them into practical systems, enabling the gap between this promising technology and final applications to be bridged. I am currently working closely with leading UK and international groups to develop next generation detectors with greatly improved performance, and to implement these detectors into advanced photon-counting applications.