Magnetometry of random AC magnetic fields using a single Nitrogen-Vacancy center

TL;DR

This paper demonstrates how a single NV center can be used to detect and analyze fluctuating AC magnetic fields, introducing methods to determine their spectral composition despite stochastic fluctuations.

Contribution

The study presents novel techniques for probing stochastic AC magnetic fields with a single NV center, including coherence revival analysis and fluorescence-based spectral reconstruction.

Findings

Stochastic fluctuations decrease NV sensitivity.

Field-dependent NV response observed.

Two methods successfully reconstruct spectral density.

Abstract

We report on the use of a single NV center to probe fluctuating AC magnetic fields. Using engineered currents to induce random changes in the field amplitude and phase, we show that stochastic fluctuations reduce the NV center sensitivity and, in general, make the NV response field-dependent. We also introduce two modalities to determine the field spectral composition, unknown a priori in a practical application. One strategy capitalizes on the generation of AC-field-induced coherence 'revivals', while the other approach uses the time-tagged fluorescence intensity record from successive NV observations to reconstruct the AC field spectral density. These studies are relevant for magnetic sensing in scenarios where the field of interest has a non-trivial, stochastic behavior, such as sensing unpolarized nuclear spin ensembles at low static magnetic fields.