Rachel Oliver

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.

Biography:

Rachel Oliver received her MEng (2000) and PhD (2003) degrees from the University of Oxford, UK. She then moved to Cambridge as a Research Fellow at Peterhouse College, and later won a prestigious Royal Society University Research Fellowship. In 2011, she took up her permanent academic position at the University of Cambridge and she is currently Professor of Materials Science and Director of the Cambridge Centre for Gallium Nitride. She held a Leverhulme Senior Research Fellowship in 2015-2016 and delivered the Rank Prize Lecture in Photonics in 2018. She was one of the Women in Engineering Society's Top 50 Women in Engineering in 2020.

Rachel's research focusses on 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 develop new nanoscale nitride structures which will provide new functionality to the devices of the future. She was the first to apply atom probe tomography to nitride materials, developed the first InGaN-based single photon source, and most recently has patented novel methods compatible with large scale manufacturing for the porosification of nitride materials. She is a founder and Chief Scientific Officer of Poro Technologies Ltd, a University spinout company exploiting her group's research on porous nitrides, and hence developing novel red microLEDs.

Rachel is also a passionate advocate for increased equality, diversity and inclusion in science and engineering and a founder member of The Inclusion Group for Equity in Research in STEMM (TIGERS). She is an Equality and Diversity Champion for the University of Cambridge School of Physical Sciences and has addressed the Parliamentary and Scientific Committee on equity issues.