  Spin-based quantum photonics promise to realize distributed quantum computing
and quantum networks. The performance depends on efficient entanglement
distribution, where the efficiency can be boosted by means of cavity quantum
electrodynamics. The central challenge is the development of compact devices
with large spin-photon coupling rates and high operation bandwidth. Photonic
crystal cavities comprise strong field confinement but put high demands on
accurate positioning of an atomic system in the mode field maximum. Color
center in diamond, and in particular the negatively-charged Silicon-Vacancy
center, emerged as a promising atom-like systems. Large spectral stability and
access to long-lived, nuclear spin memories enabled elementary demonstrations
of quantum network nodes including memory-enhanced quantum communication. In a
hybrid approach, we deterministically place SiV$^-$-containing nanodiamonds
inside one hole of a one-dimensional, free-standing, Si$_3$N$_4$-based photonic
crystal cavity and coherently couple individual optical transitions to the
cavity mode. We optimize the light-matter coupling by utilizing two-mode
composition, waveguiding, Purcell-enhancement and cavity resonance tuning. The
resulting photon flux is increased by more than a factor of 14 as compared to
free-space. The corresponding lifetime shortening to below 460 ps puts the
potential operation bandwidth beyond GHz rates. Our results mark an important
step to realize quantum network nodes based on hybrid quantum photonics with
SiV$^-$- center in nanodiamonds.
