Discovery and Optical Characterization of Hidden Silicon-Vacancy Centers in Diamond

Color centers in diamond and other wide-bandgap semiconductors have drawn a great deal of attention recently as candidate material systems for quantum devices. In spite of this, an ideal color-center qubit system has yet to be discovered, and there remain important open questions related to the inner workings of different types of color centers as well as the interactions that occur between centers situated in close proximity. Here we report a series of novel measurements [1] on a high-density sample of a particular color-center type—negatively charged silicon-vacancy (SiV^-) centers in diamond—using collinear optical multidimensional coherent spectroscopy (MDCS). The measurements reveal a hidden population of silicon-vacancy centers, which are not typically observed in photoluminescence, and which exhibit a high degree of spectral inhomogeneity and longer-than-expected single-particle electronic T₂ dephasing times. The phenomenon is likely caused by strain, indicating opportunities for controllably mediating electronic coherence in color-center-based quantum devices.

[1] C. L. Smallwood, et al., arXiv:2006.02323 (2020)