Integrated optical platforms enable the realization of complex quantum photonic circuits for a variety of applications including quantum simulations, computations, and communications. The development of on-chip integrated photon sources, providing photon quantum states with on-demand tunability, is currently an important
research area. A flexible approach for on-chip generation of entangled photons is based on spontaneous nonlinear
frequency conversion, with possibilities to integrate several photon-pair sources [1] and realize subsequent post
processing using thermo-optically or electro-optically controlled interference [2, 3]. However, deterministic postprocessing can only provide a limited set of output states, whereas quantum gates with probabilistic operation are
needed to generate arbitrary two-photon states [4]
