Interferometric Couplers for the Control of Quantum Light in Integrated Resonators

We leverage integrated ring resonators and interferometric couplers to design tunable and efficient quantum light sources. We critically review and develop theoretical models for on-chip squeezed light generation. Within this framework, we propose a Mach-Zehnder resonant interferometric coupler that selectively controls the quality factor of individual ring resonances, optimizing spontaneous four-wave mixing for the generation of high-purity heralded single photons and high-gain degenerate squeezed states. We select the waveguide material and geometry to balance the requirements of high nonlinearity, low losses, and opportune dispersion engineering. Finally, we introduce a Sagnac-interferometer-based resonant interferometric coupler to control spontaneous single-photon emission from a dipole, showcasing the versatility of resonant coupling architectures in quantum photonics.