Nonlinear Single-photon Generation for Photonic Quantum Technology

Abstract

Single photons are the smallest indivisible quanta of light, canonically described by quantum mechanics. By carefully controlling the interaction of single photons, exquisite non-classical phenomena can be observed. Mature photonic chip technology has recently emerged as an ideal platform for quantum information processing using single photons. However, generating single photons efficiently on-chip remains a fundamental challenge. One solution is to harness the intrinsic nonlinearity available in certain photonic materials for nonlinear photon generation directly in on-chip waveguides themselves. This work examines nonlinear photon generation in two key material platforms. The first is chalcogenide glass. Chalcogenide, while highly nonlinear, is amorphous and thus has broadband Raman noise. In this study the Raman noise is characterised at the single-photon level to find an intrinsic minima, which is then targeted for low-noise photon generation using an engineered waveguide. The second platform is silicon. As silicon is complementary metal-oxide-semiconductor (CMOS) fabrication compatible, it is congruent with mass production. Thus, in this study, photon-pair generation is first shown in a compact photonic crystal, before combining two monolithic sources using active multiplexing. This thesis presents significant progress towards a key goal of the field – on- demand photon generation in a fully integrated photonic quantum processor.