  Efficient on-chip integration of single-photon emitters imposes a major
bottleneck for applications of photonic integrated circuits in quantum
technologies. Resonantly excited solid-state emitters are emerging as
near-optimal quantum light sources, if not for the lack of scalability of
current devices. Current integration approaches rely on cost-inefficient
individual emitter placement in photonic integrated circuits, rendering
applications impossible. A promising scalable platform is based on
two-dimensional (2D) semiconductors. However, resonant excitation and
single-photon emission of waveguide-coupled 2D emitters have proven to be
elusive. Here, we show a scalable approach using a silicon nitride photonic
waveguide to simultaneously strain-localize single-photon emitters from a
tungsten diselenide (WSe2) monolayer and to couple them into a waveguide mode.
We demonstrate the guiding of single photons in the photonic circuit by
measuring second-order autocorrelation of g$^{(2)}(0)=0.150\pm0.093$ and
perform on-chip resonant excitation yielding a g$^{(2)}(0)=0.377\pm0.081$. Our
results are an important step to enable coherent control of quantum states and
multiplexing of high-quality single photons in a scalable photonic quantum
circuit.
