Slow-light-enhanced correlated photon pair generation in a silicon photonic crystal coupled-resonator optical waveguide

For large-scale, multi-partite photonic quantum information system, stable on-demand single photon sources are particularly important building blocks. A scheme to implement the source is to multiplex many heralded single photon sources of identical photon pair generators. To achieve this, we must increase the integration density of the photon pair generators. Slow light enhanced nonlinearity in Si photonic waveguides has proven useful for reducing the device size. So far, we demonstrated that coupled-resonator optical waveguides (CROWs) based on photonic crystal (PhC) nanocavities exhibited the largest nonlinear constant γ (/W/m) in Si-core waveguides thanks to the slow light enhancement and a strong spatial field confinement achieved by PhC nanocavities. Using the PhC-cavity-based CROW, we demonstrate efficient correlated photon pair generation.