  Silicon-vacancy and tin-vacancy defects in diamond are of interest as
alternative qubits to the NV center due to their superior optical properties.
While the availability of optical transitions in these defects is one of their
assets, high-fidelity optical coherent control has not been demonstrated. Here,
we design novel optical control schemes tailored to these defects. We evaluate
the performance of arbitrary single-qubit rotations of the electron spin qubit
both in the absence and presence of an external magnetic field, by taking into
account both coherent and incoherent errors. We find that rotations in excess
of $98.0\%$ ($T=4$~K) and $99.71\%$ ($T=6$~K) can be achieved for Si-V and Sn-V
respectively in the presence of realistic relaxation and leakage errors.
