  Silicon vacancy (V$_{Si}$) centers in 4H-silicon carbide have emerged as a
strong candidate for quantum networking applications due to their robust
electronic and optical properties including a long spin coherence lifetime and
bright, stable emission. Here, we report the integration of V$_{Si}$ centers
with a plasmonic nanocavity to Purcell enhance the emission, which is critical
for scalable quantum networking. Employing a simple fabrication process, we
demonstrate plasmonic cavities that support a nanoscale mode volume and exhibit
an increase in the spontaneous emission rate with a measured Purcell factor of
up to 48. In addition to investigating the optical resonance modes, we
demonstrate that an improvement in the optical stability of the spin-preserving
resonant optical transitions relative to the radiation-limited value. The
results highlight the potential of nanophotonic structures for advancing
quantum networking technologies and emphasizes the importance of optimizing
emitter-cavity interactions for efficient quantum photonic applications.
