Impact of strain and dark states on spectroscopic measurements of silicon-vacancy centers in diamond

Negatively charged silicon-vacancy (SiV${}^{-}$) centers in diamond offer an attractive platform for the development of many forms of quantum technology. However, questions remain in connection to how large ensembles of SiV${}^{-}$ centers behave in concert. Here, we develop a computational model designed to simulate recent experiments where optical multidimensional coherent spectroscopy (MDCS) was used to examine a high-concentration sample of SiV${}^{-}$ centers in diamond, revealing significant variations in spectral signature depending on the detection scheme. Simulation results reveal that strain effects are highly random in this system, with a characteristic axial strain of $2.8\times {10}^{-4}$ and a shear strain of $3.5\times {10}^{-5}$. They suggest in addition that highly strained centers (with values exceeding $1.5\times {10}^{-5}$) may become significantly decoupled from optical emission. The results have implications for the use of SiV${}^{-}$ centers as quantum sensors.