Hidden Silicon-Vacancy Centers in Diamond

We characterize a high-density sample of negatively charged silicon-vacancy (${\mathrm{SiV}}^{\ensuremath{-}}$) centers in diamond using collinear optical multidimensional coherent spectroscopy. By comparing the results complementary signal detection schemes, we identify hidden population ${\mathrm{SiV}}^{\ensuremath{-}}$ that is not typically observed photoluminescence and which exhibits significant spectral inhomogeneity extended electronic ${T}_{2}$ times. The phenomenon likely caused by strain, indicating potential mechanism for controlling electric coherence color-center-based quantum devices.