A robust observation of neutrinoless double beta decay is currently the only known method to determine the Majorana nature of the neutrino. The detection of the single barium ion produced as a result of the double beta decay of xenon 136 would enable a new class of ultra-low background neutrinoless double beta decay experiments. However, despite more than 20 years of R&D, a credible method to collect and identify individual barium ions in bulk xenon has remained elusive. We will present a recent milestone in barium tagging R&D: single barium dication resolution using the technique of single molecule fluorescence imaging (SMFI). This R&D adapts techniques from biochemistry and microscopy to yield a novel technology with potential to extend the sensitivity of neutrinoless double beta decay searches. Individual ions are resolved with high statistical significance and with super-resolution on the nanometer scale. We will present on recent developments and current status.