Theory of Quantum Light Sources: how can we make coherent single photons in solid state systems?

Supervisor: Dr Brendon Lovett (St Andrews)

The generation of indistinguishable single photons on demand is a key requirement for many kinds of future quantum technologies, such as secure communication and optical quantum computing [1]. Being able to make coherent quantum light sources in solid state systems would enable us to create on-chip photonic circuits that would enable this technology. It is therefore of the utmost importance to understand what effect a solid state environment has on the fidelity of emitted photons. In this project, you will exploit and developing a groundbreaking new technique our group has created for simulating open quantum systems [2]. Based on a combination of Feynman's path integrals [3,4] and matrix product states [5], it has already enabled calculations impossible by more traditional means. You will study how the technique might be used to calculate the photon correlation functions that characterise a single photon source, in the presence of a strongly-coupled environment of vibrational modes of the crystal. You will go on to study how a photonic cavity might be used to improve the performance of such a device. [1] I. Aharonovich. D. Englund and Milos Toth, Nature Photonics 10 631 (2016) [2] A. Strathearn, P. Kirton, D. Kilda, J. Keeling, and B. W. Lovett. , Nature Communications 9 3322 (2018) [3] R. P. Feynman, and F. L. Vernon, Jr., Ann. Phys. 24 118 (1963) [4] N. Makri and D. E. Makarov. The Journal of Chemical Physics J. Chem. Phys. 102 4600 (1995) [5] R. Orús, Annals of Physics 349 117 (2014)