Supervisors: Anthony Laing, Jeremy O’Brien, Terry Rudolph

Integrated Quantum Photonics

Single photons make ideal carriers of quantum information due to their intrinsic low-noise properties and ease of manipulation.  They are also the natural candidates for any form of quantum communication procedure due to their high speed transmission.

By encoding information in the spatial modes of single photons propagating through linear optical networks consisting of beamsplitters and phase shifters and using photon measurement to induce nonlinearity, it is possible to achieve universal quantum computation. Such devices are still a long-term prospect though, requiring improvements in current photon source, detector and circuit technology. However, recent evidence suggests that the multi-photon quantum interference exhibited in linear optical networks allows them to sample from distributions which are intractable for classical computers to calculate, even with just tens of photons.

Integrated waveguide chips are a promising development for the realisation of such networks, providing high performance, thanks to inherent interferometric stability, and scalability, due to their modular and miniaturised nature. Using resistive heaters to tune phase shifts allows for the implementation of reconfigurable arbitrary unitary circuits. This project will investigate the applications and development of this powerful platform for a broad range of quantum information experiments, from boson-sampling to tests of the foundations of physics.