Optically-detected NMR of optically-hyperpolarized ³¹P neutral donors in ²⁸Si

The electron and nuclear spins of the shallow donor ³¹P are promising qubit candidates invoked in many proposed Si-based quantum computing schemes. We have recently shown that the near-elimination of inhomogeneous broadening in highly isotopically enriched ²⁸Si enables an optical readout of both the donor electron and nuclear spins by resolving the donor hyperfine splitting in the near-gap donor bound exciton transitions. We have also shown that pumping these same transitions can very quickly produce large electron and nuclear hyperpolarizations at low magnetic fields, where the equilibrium electron and nuclear polarizations are very small. Here we show preliminary results of the measurement of ³¹P neutral donor NMR parameters using this optical nuclear hyperpolarization mechanism for preparation of the ³¹P nuclear spin system, followed by optical readout of the resulting nuclear spin population after manipulation with NMR pulse sequences. This allows for the observation of single-shot NMR signals with very high signal-to-noise ratio under conditions where conventional NMR is not possible, due to the low concentration of ³¹P and the small equilibrium polarization.