DC Quantum Magnetometry Below the Ramsey Limit

TL;DR

This paper presents a novel quantum magnetometry technique using rotating nitrogen-vacancy centers in diamond, surpassing traditional sensitivity limits for dc magnetic field detection by over tenfold.

Contribution

It introduces a method that up-converts dc fields while maintaining quantum coherence, significantly enhancing sensitivity beyond the Ramsey limit.

Findings

Sensitivity exceeds $T_2^*$-limited magnetometry by over an order of magnitude

Method preserves quantum coherence during measurement

Sensitivity depends on measurement time and rotation speed

Abstract

We demonstrate quantum sensing of dc magnetic fields that exceeds the sensitivity of conventional $T_2^\ast$-limited dc magnetometry by more than an order of magnitude. We used nitrogen-vacancy centers in a diamond rotating at periods comparable to the spin coherence time, and characterize the dependence of magnetic sensitivity on measurement time and rotation speed. Our method up-converts only the dc field of interest and preserves the quantum coherence of the sensor. These results definitively improve the sensitivity of a quantum magnetometer to dc fields, an important and useful addition to the quantum sensing toolbox.