Sensitivity-enhanced magnetometry using nitrogen-vacancy ensembles via adaptively complete transitions overlapping

TL;DR

This paper presents a method to enhance the sensitivity of NV ensemble magnetometry by overlapping spin transitions with adaptive bias magnetic fields, achieving significant improvements in magnetic field detection sensitivity.

Contribution

The study introduces an adaptive calibration technique using particle swarm optimization to automatically generate bias magnetic fields for overlapped NV transitions, improving magnetometry sensitivity.

Findings

Achieved 1.5 times sensitivity enhancement over separate transitions.

Reached a magnetic field sensitivity of 855 pT/√Hz with overlapped transitions.

Demonstrated applicability for direction-fixed magnetic sensing.

Abstract

Nitrogen-vacancy (NV) centers in diamond are suitable sensors of high-sensitivity magnetometry which have attracted much interest in recent years. Here, we demonstrate sensitivity-enhanced ensembles magnetometry via adaptively complete transitions overlapping with a bias magnetic field equally projecting onto all existing NV orientations. Under such conditions, the spin transitions corresponding to different NV orientations are completely overlapped which will bring about an obviously improved photoluminescence contrast. And we further introduce particle swarm optimization into the calibration process to generate this bias magnetic field automatically and adaptively using computer-controlled Helmholtz coils. By applying this technique, we realize an approximate 1.5 times enhancement and reach the magnetic field sensitivity of $\rm855\ pT/\sqrt{Hz}$ for a completely overlapped transitions compared to $\rm 1.33\ nT/\sqrt{\rm Hz}$ for a separate transition on continuous-wave magnetometry. Our approach can be conveniently applied to direction-fixed magnetic sensing and obtain the potentially maximum sensitivity of ensemble-NV magnetometry.