Rapid, in Situ Neutralization of Nitrogen- and Silicon-Vacancy Centers in Diamond Using Above-Band Gap Optical Excitation

The charge state of a quantum point defect in a solid-state host strongly determines its optical and spin characteristics. Consequently, techniques for controlling the charge state are required to realize technologies for quantum networking and sensing. In this work, we demonstrate the use of deep-ultraviolet (DUV) radiation to dynamically neutralize nitrogen- (NV) and silicon-vacancy (SiV) centers. We first examine the neutralization of NV by correlating the NV^- and NV⁰ spectra, indicating > 99% polarization into NV⁰. We then examine the time dynamics of SiV^- photoluminescence, observing an 80% reduction of intensity within a single 100 μs DUV pulse. Finally, we demonstrate that this DUV-induced bleaching is accompanied by a dramatic increase in the SiV⁰ population that is robust to extended periods of near-infrared excitation. Our results indicate the potential of above-band gap excitation as a universal means of generating neutral charge states of quantum point defects on demand.