IEEE Photonics Society Distinguished Lecture: Nitrides for quantum light sources

#Photonics #DL

Speaker: Prof. Rachel Oliver, Department of Materials Science and Metallurgy, University of Cambridge

Abstract: A quantum light source is a device that can generate one single photon – or an entangled pair of photons - on demand.  Whilst a single photon emitter would be pretty useless as a car headlight or bedside lamp, these devices are in increasing demand for new developments in optical communication which might exploit fundamental principles of quantum physics to achieve data security.  Linear optical quantum computation, precision optical measurement and even random number generation also present potential applications opportunities for such light sources.   However, many of the most mature quantum light sources operate at temperatures only accessible using liquid helium, at best inconvenient and at worst prohibitive for applications.  Exploiting nitride semiconductors allows device concepts developed in the more conventional arsenide semiconductor family to be applied, but whilst arsenide devices are limited to cryogenic temperatures, nitride devices can operate at temperatures accessible using on-chip, Peltier cooling, and in some cases even at room temperature.    Unfortunately, working with these less mature semiconductors has its pitfalls: high densities of defects and the impact of internal electric fields can limit device performance.  For example, the wavelength of emission from nitride single photon emitters wanders with time, which is not compatible with applications which demand resonance of the emitter with a cavity or (more stringently) the emission of indistinguishable photons. Nitrides crystals grown in unusual orientations can overcome these challenges whilst maintaining good temperature stability, providing new opportunities for real-world quantum technologies.

Bio: Professor Rachel Oliver is Director of the Cambridge Centre for Gallium Nitride.  She leads research projects across the full range of the Centre’s activities, and her personal passion is understanding how the small scale structure of nitride materials effects the performance and properties of devices. She uses expertise in microscopy and materials growth to lead the development of new nanoscale nitride structures which will provide new functionality to the devices of the future. She is also passionate about communicating science to the general public and hence widening participation in science by under-represented groups, particularly women. Dr. Oliver is a Fellow of the Royal Academy of Engineering.