Coherent control of a nitrogen-vacancy center spin ensemble with a diamond mechanical resonator

Coherent control of the nitrogen-vacancy (NV) center in diamond's triplet spin state has traditionally been accomplished with resonant ac magnetic fields. Here, we show that high-frequency stress resonant with the spin state splitting can also coherently control NV center spins. Because this mechanical drive is parity non-conserving, controlling spins with stress enables direct access to the magnetically forbidden vertical bar -1 > <-> vertical bar + 1 > spin transition. Using a bulk-mode mechanical microresonator fabricated from single-crystal diamond, we apply intense ac stress to the diamond substrate and observe mechanically driven Rabi oscillations between the vertical bar -1 > and vertical bar + 1 > states of an NV center spin ensemble. Additionally, we measure the inhomogeneous spin dephasing time (T-2*) of the spin ensemble within this {-1, +1} subspace using a mechanical Ramsey sequence and compare it to the dephasing times measured with a magnetic Ramsey sequence for each of the three spin qubit combinations available within the NV center ground state. These results demonstrate coherent control of a spin with a mechanical resonator and could lead to the creation of a phase-sensitive Delta-system inside the NV center ground state with potential applications in quantum optomechanics and metrology. (C) 2015 Optical Society of America.