Scanning gradiometry with a single spin quantum magnetometer

TL;DR

This paper introduces a novel scanning gradiometry technique using a single spin quantum magnetometer, significantly improving sensitivity and spatial resolution for imaging weak magnetic fields.

Contribution

The authors develop a mechanical oscillation method of a single nitrogen-vacancy center to enhance magnetic field gradient imaging with quantum protocols.

Findings

Achieved an order-of-magnitude sensitivity improvement.

Produced sharper, more localized magnetic images.

Effectively suppressed field drifts during imaging.

Abstract

Here, we demonstrate a gradiometry technique that significantly enhances the measurement sensitivity of such static fields, leading to new opportunities in the imaging of weakly magnetic systems. Our method relies on the mechanical oscillation of a single nitrogen-vacancy center at the tip of a scanning diamond probe, which up-converts the local spatial gradients into ac magnetic fields enabling the use of sensitive ac quantum protocols. We show that gradiometry provides important advantages over static field imaging: (i) an order-of-magnitude better sensitivity, (ii) a more localized and sharper image, and (iii) a strong suppression of field drifts. We demonstrate the capabilities of gradiometry by imaging the nanotesla fields appearing above topographic defects and atomic steps in an antiferromagnet, direct currents in a graphene device, and para- and diamagnetic metals.