We characterize a high-density sample of negatively charged silicon-vacancy (SiV−) centers in diamond using collinear optical multidimensional coherent spectroscopy. By comparing the results of complementary signal detection schemes, we identify a hidden population of \ce{SiV^-} centers that is not typically observed in photoluminescence, and which exhibits significant spectral inhomogeneity and extended electronic T2 times. The phenomenon is likely caused by strain, indicating a potential mechanism for controlling electric coherence in color-center-based quantum devices.
@article{arxiv.2006.02323,
title = {Hidden Silicon-Vacancy Centers in Diamond},
author = {Christopher L. Smallwood and Ronald Ulbricht and Matthew W. Day and Tim Schröder and Kelsey M. Bates and Travis M. Autry and Geoffrey Diederich and Edward Bielejec and Mark E. Siemens and Steven T. Cundiff},
journal= {arXiv preprint arXiv:2006.02323},
year = {2021}
}