A field-deployable absolute vector quantum magnetometer for geomagnetic research

Quantum magnetic sensing offers several powerful advantages over the classic combination of triaxial fluxgate and proton precession magnetometers. Advances in quantum technology, such as optically-pumped magnetometers (OPMs), have enabled single sensors to make full-field, high-frequency, temperature-insensitive measurements of the natural field (i.e., 0-60μT). The low noise, high bandwidth OPMs can be used to detect absolute changes in the field arising from secular variation as well as rapid variations in the Earth’s natural magnetic field from space weather activity. Our newly developed OPM consists of a Cs-vapour cell magnetometer in a double-resonance configuration with two orthogonal coils to provide a full field and vector measurement capability.

As part of a three-year programme, we will build and deploy five ground-based OPMs using state-of-the-art sensor technology from the University of Strathclyde in combination with back-end electronics for the laser driver and high-speed digital signal processing developed by RAL Space. The BGS-run geomagnetic observatory at Eskdalemuir will allow the OPM systems to be compared and checked against the highest scientific standards for observatories (INTERMAGNET-standard). The sensors will then be deployed to five field locations around Britain in 2025. This will reduce the spacing between operational observatories and variometers in the UK to less than 200 km. The systems will return data in near-real-time, allowing one of the densest magnetic networks in the world to be created. We describe the progress to date, including the results from a performance comparison at Eskdalemuir and the first field deployments in England and Wales.