A subpicotesla diamond magnetometer

TL;DR

This paper demonstrates a diamond magnetometer using an ensemble of defect centers achieving record sensitivity of 0.9 pT/Hz^(1/2) at room temperature, significantly surpassing previous single-center sensors.

Contribution

The work introduces a highly sensitive diamond magnetometer based on defect center ensembles, achieving photon shot noise limited sensitivity of 0.9 pT/Hz^(1/2).

Findings

Achieved a sensitivity of 0.9 pT/Hz^(1/2) at room temperature.

Measured the smallest magnetic field of 100 fT.

Demonstrated potential for further improvements with decoupling sequences.

Abstract

Diamond defect centers are promising solid state magnetometers. Single centers allow for high spatial resolution field imaging but are limited in their magnetic field sensitivity to around 10 nT/Hz^(1/2) at room-temperature. Using defect center ensembles sensitivity can be scaled as N^(1/2) when N is the number of defects. In the present work we use an ensemble of 1e11 defect centers for sensing. By carefully eliminating all noise sources like laser intensity fluctuations, microwave amplitude and phase noise we achieve a photon shot noise limited field sensitivity of 0.9 pT/Hz^(1/2) at room-temperature with an effective sensor volume of 8.5e-4 mm^3. The smallest field we measured with our device is 100 fT. While this denotes the best diamond magnetometer sensitivity so far, further improvements using decoupling sequences and material optimization could lead to fT/Hz^(1/2) sensitivity.