Integrated quantum photonic waveguide circuits are a promising approach to realizing future photonic quantum technologies. Here, we present an integrated photonic quantum technology platform utilizing the silicon-oninsulator material system, where quantum interference and the manipulation of quantum states of light are demonstrated in components orders of magnitude smaller than previous implementations. Two-photon quantum interference is presented in a multi-mode interference coupler, and the manipulation of entanglement is demonstrated in a Mach–Zehnder interferometer, opening the way to an all-silicon photonic quantum technology platform.