Fig. 1: Integrated platform for the parallel processing of quantum frequency combs.

a Schematic to show the device layout for the parallel processing of QFCs. The continuous-wave pump (green) is coupled onto the chip, equally split with a Y-junction, and coupled into the integrated ring cavity in both CW and CCW directions. Intra-cavity parametric down-conversion generates frequency-entangled photon pairs across multiple cavity resonances. Output photon pairs are interfered with tunable relative phase φ on a 50/50 multimode interferometer. A separate bus waveguides is used to calibrate the device. b Output state structure with frequency correlation in symmetric spectral modes across CW and CCW paths.