Wide-field diamond magnetometry with millihertz frequency resolution and nanotesla sensitivity

TL;DR

This paper introduces 'iQdyne,' a new protocol that significantly enhances the frequency resolution of wide-field diamond magnetometry beyond the NV center's coherence limit, enabling more precise biological magnetic measurements.

Contribution

The paper presents the 'iQdyne' measurement protocol, achieving sub-Hertz frequency resolution in wide-field diamond magnetometry, surpassing previous coherence-limited methods.

Findings

Achieved 238 mHz frequency resolution.

Demonstrated magnetic sensitivity of 65 nT/√Hz.

Performance matches analytical model predictions.

Abstract

The nitrogen-vacancy (NV) center in diamond allows room-temperature wide-field quantum magnetometry and metrology for a small volume, which is an important technology for applications in biology. Although coherence of the NV center has a limited frequency resolution of diamond magnetometry to 10-100 kHz, recent studies have shown that a phase sensitive protocol can beat the coherence limit on a confocal setup. Here, we report a new measurement protocol, "iQdyne," for improving the frequency resolution of wide-field imaging beyond the coherence limit of the NV center. We demonstrate wide-field magnetometry with a frequency resolution of 238 mHz and a magnetic sensitivity of 65 nT/sqrtHz, which are superior to the conventional XY8-based technique, which paves the way to in vivo microscale nuclear magnetic resonance imaging. We find that the experimental performance of iQdyne agrees well with that of an analytical model.