LAUSR

Deterministic control and detection of its charge state with high spatial resolution are what make the nitrogen-vacancy (N-$V$) center in diamond appealing for nanoscale quantum sensing and biological tracking. Usually high laser power is needed, though, which induces photodamage and decreases sensitivity. By also applying a weak $n\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}r-i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}f\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}d$ laser, the authors significantly accelerate charge-state conversion by $v\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}b\phantom{\rule{0}{0ex}}l\phantom{\rule{0}{0ex}}e$ photons, permitting decreased laser power for the subsequent nanoscopy. This could help to realize high spatial resolution and sensitivity, particularly for work on live cells.