Reversible Optical Data Storage below the Diffraction Limit

Color centers in wide-bandgap semiconductors feature metastable charge statesthat can be interconverted with the help of optical excitation at selectwavelengths. The distinct fluorescence and spin properties in each of thesestates have been exploited to show storage of classical information in threedimensions, but the memory capacity of these platforms has been thus farlimited by optical diffraction. Here, we leverage local heterogeneity in theoptical transitions of color centers in diamond to demonstrate selective chargestate control of individual point defects sharing the same diffraction-limitedvolume. Further, we apply this approach to dense color center ensembles, andshow rewritable, multiplexed data storage with large areal density. Theseresults portend alternative approaches to information processing in the form ofdevices with enhanced optical storage capacity.