Reliable sources of photons will be required to develop many photonic quantum technologies. Current on-demand sources are lacking in brightness, compactness, and scalability. Here, we review the use of silicon photonic crystal waveguides as nonlinear photon generators in the 1550 nm band.
We show that these photon sources can create strong frequency correlations, that the predictability of photon generation can be improved through the active multiplexing of many sources, and that photons from these sources can be useful for quantum communication.