  We propose a fast, scalable all-optical design for arbitrary two-qubit
operations for defect qubits in diamond (NV centers) and in silicon carbide,
which are promising candidates for room temperature quantum computing. The
interaction between qubits is carried out by microcavity photons. The approach
uses constructive interference from higher energy excited states activated by
optical control. In this approach the cavity mode remains off-resonance with
the directly accessible optical transitions used for initialization and
readout. All quantum operations are controlled by near-resonant
narrow-bandwidth optical pulses. We perform full quantum numerical modeling of
the proposed gates and show that high-fidelity operations can be obtained with
realistic parameters.
