From fast magnetometry to single-molecule magnetic resonance with quantum sensors

Nitrogen–vacancy (NV) centers in diamond are atom-sized quantum sensors that can detect minute magnetic fields at the nanoscale, from condensed-matter systems to individual nuclear and electronic spins in molecular analytes. Their exceptional bandwidth enables sensing across a broad range of frequencies and time scales, including transient signals on the nanosecond scale in solid-state systems.

Beyond detecting classical magnetic fields, NV centers allow us to probe spin–spin couplings and dipolar interactions with nearby spins, opening the door to nanoscale NMR and EPR spectroscopy of single molecules and few-molecule ensembles. This platform provides a clean setting to explore spin-coupling hierarchies at the fundamental level, while also advancing the long-standing goal of determining molecular structure at the single-molecule level.

Recently, NV centers have been proposed as probes of photogenerated spin-correlated radical pairs (SCRPs), by tracking charge separation and recombination, spin dynamics, and, most recently, spin polarization effects attributed to chirality-induced spin selectivity (CISS). Combining stabilization of shallow NV centers with tailored surface functionalization for specific molecular targets enables the measurement of transient magnetic fields in diverse molecular systems, with high sensitivity and nanoscale spatial resolution under ambient conditions.

In this talk, I will discuss key experimental challenges in sensing transient magnetic fields with single, shallow NV centers, strategies to overcome these limitations, and recent advances spanning fast magnetometry to few-molecule magnetic resonance and transients in photogenerated radical pairs.