  Semiconductor quantum photonic circuits can be used to efficiently generate,
manipulate, route and exploit non-classical states of light for distributed
photon based quantum information technologies. In this article, we review our
recent achievements on the growth, nanofabrication and integration of
high-quality, superconducting niobium nitride thin films on optically active,
semiconducting GaAs substrates and their patterning to realise highly efficient
and ultrafast superconducting detectors on semiconductor nanomaterials
containing quantum dots. Our state-of-the-art detectors reach external
detection quantum efficiencies up to 20% for ~4nm thin films and single photon
timing resolutions <72ps. We discuss the integration of such detectors into
quantum dot loaded, semiconductor ridge waveguides, resulting in the on-chip,
time-resolved detection of quantum dot luminescence. Furthermore, a prototype
quantum optical circuit is demonstrated that enabled the on-chip generation of
resonance fluorescence from an individual InGaAs quantum dot, with a line width
<15 $\mu$eV displaced by 1mm from the superconducting detector on the very same
semiconductor chip. Thus, all key components required for prototype quantum
photonic circuits with sources, optical components and detectors on the same
chip are reported.
