  Single photon sources (SPSs) form an essential resource for many quantum
information technologies. We demonstrate how the inclusion of coherent feedback
in a scalable waveguide system, can significantly improves the two key figures
of merit: coherence and indistinguishability. Our feedback protocol is
simulated using a quantum trajectory discretized waveguide model which can be
used to directly model Hanbury Brown and Twiss (HBT) and Hong-Ou-Mandel (HOM)
interferometers. With the proper choice of the round trip phase, the
non-Markovian dynamics from the time-delayed feedback enhances the spontaneous
emission rate and improves the coherence and indistinguishability of the SPS by
up to 56%. We also show how this mechanism suppresses the effects of unwanted
dissipation channels such as off-chip decay and pure dephasing.
