  $^{171}$Yb$^{3+}$ in YVO$_4$ is a promising candidate for building quantum
networks with good optical addressability, excellent spin properties and a
secondary nuclear-spin quantum register. However, the associated long optical
lifetime necessitates coupling to optical resonators for faster emission of
single photons and to facilitate control of single $^{171}$Yb ions. Previously,
single $^{171}$Yb ions were addressed by coupling them to monolithic photonic
crystal cavities fabricated via lengthy focused ion beam milling. Here, we
design and fabricate a hybrid platform based on ions coupled to the
evanescently decaying field of a GaAs photonic crystal cavity. We
experimentally detect and demonstrate coherent optical control of single
$^{171}$Yb ions. For the most strongly coupled ions, we find a 64 fold
reduction in lifetime. The results show a promising route towards a quantum
network with $^{171}$Yb:YVO$_4$ using a highly scalable platform.
