  The identification of new solid-state defect qubit candidates in widely used
semiconductors has the potential to enable the use of nanofabricated devices
for enhanced qubit measurement and control operations. In particular, the
recent discovery of optically active spin states in silicon carbide thin films
offers a scalable route for incorporating defect qubits into on-chip photonic
devices. Here we demonstrate the use of 3C silicon carbide photonic crystal
cavities for enhanced excitation of color center defect spin ensembles in order
to increase measured photoluminescence signal count rates, optically detected
magnetic resonance signal intensities, and optical spin initialization rates.
We observe up to a factor of 30 increase in the photoluminescence and ODMR
signals from Ky5 color centers excited by cavity resonant excitation and
increase the rate of ground-state spin initialization by approximately a factor
of two. Furthermore, we show that the small excitation mode volume and enhanced
excitation and collection efficiencies provided by the structures can be used
to study inhomogeneous broadening in defect qubit ensembles. These results
highlight some of the benefits that nanofabricated devices offer for
engineering the local photonic environment of color center defect qubits to
enable applications in quantum information and sensing.
