  The interaction of solid-state electronic spins with deformations of their
host crystal is an important ingredient in many experiments realizing quantum
information processing schemes. Here, we theoretically characterize that
interaction for a nitrogen-vacancy (NV) center in diamond. We derive the
symmetry-allowed Hamiltonian describing the interaction between the
ground-state spin-triplet electronic configuration and the local strain. We
numerically calculate the six coupling-strength parameters of the Hamiltonian
using density functional theory, and propose an experimental setup for
measuring those coupling strengths. The importance of this interaction is
highlighted by the fact that it enables to drive spin transitions, both
magnetically allowed and forbidden, via mechanically or electrically driven
spin resonance. This means that the ac magnetic field routinely used in a wide
range of spin-resonance experiments with NV centers could in principle be
replaced by ac strain or ac electric field, potentially offering lower power
requirements, simplified device layouts, faster spin control, and local
addressability of electronic spin qubits.
