Nitrogen-vacancy centers in diamond as room-temperature quantum magnetometers: the physics, the readout, sensitivity limits, and real applications.
A nitrogen-vacancy center is a point defect in diamond where a nitrogen atom sits beside a vacancy in the carbon lattice. Its electron spin can be initialised and read out optically at room temperature, which makes it usable as a magnetometer without cryogenics or vacuum. This guide covers the defect physics, optically detected magnetic resonance readout, what sets sensitivity limits, how NV sensors compare with SQUIDs and optically pumped magnetometers, and where they are being applied in navigation, materials characterisation, and biomedical imaging.