  High-efficiency photon-pair production is a long-sought-after goal for many
optical quantum technologies, and coherent photon conversion processes are
promising candidates for achieving this. We show theoretically how to control
coherent conversion between a narrow-band pump photon and broadband photon
pairs in nonlinear optical waveguides by tailoring frequency dispersion for
broadband quantum frequency mixing. We reveal that complete deterministic
conversion as well as pump-photon revival can be achieved at a finite
propagation distance. We also find that high conversion efficiencies can be
realised robustly over long propagation distances. These results demonstrate
that dispersion engineering is a promising way to tune and optimise the
coherent photon conversion process.
