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 [1]. 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 [2,3]. 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 [4] 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.