Résumé
The nitrogen-vacancy (NV) defect in diamond is an efficient quantum sensor of randomly fluctuating signalsvia relaxometry measurements. In particular, the longitudinal spin relaxation of the NV defect accelerates in thepresence of magnetic noise with a spectral component at its electron spin resonance frequency.We look into thiseffect quantitatively by applying a calibrated and tunable magnetic noise on a single NV defect.We show that anincrease of the longitudinal spin relaxation rate translates into a reduction of the photoluminescence (PL) signalemitted under continuous optical illumination, which can be explained using a simplified three-level model of theNV defect. This PL quenching mechanism offers a simple, all-optical method to detect magnetic noise sourcesat the nanoscale.