Diamond magnetometry and gradiometry towards subpicotesla DC field measurement

TL;DR

This paper demonstrates a highly sensitive diamond-based magnetometer using NV centers with low optical power, achieving subpicotesla DC field detection and exploring gradiometry for unshielded environments.

Contribution

It introduces a low-intensity optical excitation method for NV ensemble magnetometry and compares different DC measurement techniques for optimal sensitivity.

Findings

Minimum detectable field of 0.3-0.7 pT in 73 seconds

Magnetic field sensitivity of 2.6-6 pT/Hz^0.5

Potential for wide bandwidth, ambient condition magnetometry

Abstract

Nitrogen vacancy (NV) centers in diamond have developed into a powerful solid-state platform for compact quantum sensors. However, high sensitivity measurements usually come with additional constraints on the pumping intensity of the laser and the pulse control applied. Here, we demonstrate high sensitivity NV ensemble based magnetic field measurements with low-intensity optical excitation. DC magnetometry methods like, e.g., continuous-wave optically detected magnetic resonance and continuously excited Ramsey measurements combined with lock-in detection, are compared to get an optimization. Gradiometry is also investigated as a step towards unshielded measurements of unknown gradients. The magnetometer demonstrates a minimum detectable field of 0.3-0.7 pT in a 73 s measurement by further applying a flux guide with a sensing dimension of 2 mm, corresponding to a magnetic field sensitivity of 2.6-6 pT/Hz^0.5. Combined with our previous efforts on the diamond AC magnetometry, the diamond magnetometer is promising to perform wide bandwidth magnetometry with picotesla sensitivity and a cubic-millimeter sensing volume under ambient conditions.