  Photons, by nature, typically do not exhibit interactions with each other.
Creating photon-photon interactions holds immense importance in both
fundamental physics and quantum technologies. Currently, such interactions have
only been achieved indirectly as mediated by atomic-like quantum emitters with
resonant photon-atom interactions. However, the use of these indirect
interactions presents substantial fundamental challenges that impede scaling
and practical applications. Here we demonstrate creation of non-classical
photon correlations, including photon anti-bunching, via a passive InGaP
photonic integrated circuit. Our approach employs the quantum interference
between uncorrelated light and the two-photon bound state, the latter of which
arises from the $\chi^{(2)}$-mediated photon interaction. Our work opens a new
route in controlling quantum light by harnessing highly-engineerable bulk
optical nonlinearities, which has significant implications for nonlinear
optical quantum information processing and quantum networking.
