Quantum magnetometry with optically active spins

Quantum magnetometry based on optically active spin defects has emerged as a powerful platform for sensing magnetic fields with high sensitivity, spatial resolution, and operability under ambient conditions. Systems ranging from solid-state defects (such as NV centers in diamond) to molecular spin platforms provide optical initialization and readout, long coherence times, and flexible control, enabling applications from the nanoscale to the mesoscopic regime. These capabilities have positioned spin-based quantum sensors as versatile tools across physics, chemistry, materials science, and the life sciences.

In this workshop, I will introduce the basic principles of quantum magnetometry with optically active spins, focusing on exemplary sensing protocols and control strategies that shape sensitivity, bandwidth, and spectral selectivity. I will then survey the current state of the art, highlighting recent advances ranging from entanglement-enhanced sensing to multiparameter sensing and correlation-based detection, as well as the integration of spin systems into nanostructures and hybrid platforms. Finally, I will discuss emerging applications, including nanoscale NMR, imaging of quantum materials, precision metrology and sensing in complex biological and chemical environments, outlining both current capabilities and key open challenges.