In an exemplary embodiment, a structure comprises a plurality of deterministically positioned optically active defects, wherein each of the plurality of deterministically positioned optically active defects has a linewidth within a factor of one hundred of a lifetime limited linewidth of optical transitions of the plurality of deterministically positioned optically active defects, and wherein the plurality of deterministically positioned optically active defects has an inhomogeneous distribution of wavelengths, wherein at least half of the plurality of deterministically positioned optically active defects have transition wavelengths within a less than 8 nm range. In a further exemplary embodiment, method of producing at least one optically active defect comprises deterministically implanting at least one ion in a structure using a focused ion beam; heating the structure in a vacuum at a first temperature to create at least one optically active defect; and heating the structure in the vacuum at a second temperature to remove a plurality of other defects in the structure, wherein the second temperature is higher than the first temperature.