High-rate photon pairs and sequential Time-Bin entanglement with Si₃N₄ microring resonators

Integrated photonics is increasing in importance for compact, robust, and scalable enabling quantum technologies. This is particularly interesting for developing quantum communication networks, where resources need to be deployed in the field. We exploit photonic chip-based Si₃N₄ microring resonators to realise a photon pair source with low-loss, high-noise suppression and coincidence rates of 80×10³ s^-1. A simple photonic noise characterisation technique is presented that distinguishes linear and nonlinear contributions useful for system design and optimisation. We then demonstrate an all-fiber 750 MHz clock-rate sequential Time-Bin entanglement scheme with raw interference visibilities > 98 %.