Optical detection of the spin state of a single nucleus in silicon

We propose a method to optically detect the spin state of a ³¹P nucleus embedded in a ²⁸Si matrix. The nuclear-electron hyperfine splitting of the ³¹P neutral-donor ground state can be resolved via a direct frequency discrimination measurement of the ³¹P-bound exciton photoluminescence using single-photon detectors. The measurement time is expected to be shorter than the optically modified lifetime of the nuclear spin at 4 K and 10 T.