Fig. 5. Measured second-order correlation g⁽²⁾ (Eq. 4) for the signal and idler (green and orange points, respectively) and for coherent states (gray points) for different values of photon number n.

Data are collected over a range of pump pulse energies corresponding approximately to 0.1- to 1-nJ on-chip. Coherent state data were acquired using attenuated laser pulses and show excellent agreement with the predicted g⁽²⁾ = 1 for coherent states.