Mesoscopic magnetic resonance spectroscopy with a remote spin sensor

Mesoscopic magnetic resonance at lengths of 0.1---10 $\ensuremath{\mu}$m is vital in many areas of research, including structural biology and medical diagnostics. Magnetic resonance based on detecting spin fluctuations with nitrogen-vacancy centers in diamond is a powerful tool at the nanoscale, but this approach sputters in the mesoscopic regime, as signals fall off cubically with distance. This study surmounts the problem by instead detecting spin $p\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}l\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}z\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}n$, extending the sensor-to-sample distance to tens of $\ensuremath{\mu}$m, rather than the tens of nm in previous work. This remote-sensing approach will have an impact on bioimaging applications at the subcellular level.