Multiplexed Data Storage at Cryogenic Temperatures in Diamond

Wide bandgap semiconductors host point defects whose absorption characteristics are known to give gems their signature color. These color centers feature metastable charge states that can be interconverted with the help of optical excitation at select wavelengths. The distinct fluorescence and spin properties in each of these states have already been exploited to show storage of classical information in three dimensions, but the memory capacity of color center platforms has been limited thus far by optical diffraction. Here, we leverage strain-induced heterogeneity in the optical transitions of the nitrogen-vacancy (NV) center in diamond to demonstrate sub-diffraction charge state control of individual point defects. We first focus on pairs of color centers within the same diffraction-limited volume and show selective charge state preparation of individual NVs. Further, we extend this approach to dense color center ensembles, and show rewritable, wavelength-multiplexed data storage with large areal densities. These results portend opportunities for alternative approaches to information processing in the form of devices with enhanced optical storage capacity.