Optical source of individual pairs of colour-conjugated photons

We theoretically demonstrate that Kerr nonlinearity in optical circuits can lead to both resonant four-wave mixing and photon blockade, which can be used for high-yield generation of high-fidelity individual photon pairs with conjugated frequencies. We propose an optical circuit, which, in the optimal pulsed-drive regime, would produce photon pairs at the rate up to 5 × 10⁵  s ^-1 (0.5 pairs per pulse) with [Formula: see text] for one of the conjugated frequencies. We show that such a scheme can be utilised to generate colour-entangled photons.