Ultrawide Bandwidth Optomechanical Magnetometry Using Flux Concentration
Abstract
Low-frequency magnetic fields carry vital information for neuroscience, navigation, and Earth science. However, they are generally weak, making it challenging to measure them with compact, room-temperature magnetometers. To overcome this challenge, we combine an on-chip optomechanical magnetometer with a high-permeability flux concentrator. Beyond boosting sensitivity and bandwidth, exploiting the concentrator's nonlinear response converts low-frequency magnetic fluctuations into higher-frequency signals where the sensor is intrinsically most responsive. This sidesteps the technical noise that has long constrained the application of optomechanical magnetometry at low frequencies. Our measurements show order-of-magnitude improvements in sensitivity and extend performance into the sub-hertz regime, achieving below 20 nT Hz down to 3 Hz and less than 100 nT Hz at 0.1 Hz. Because this approach requires no redesign of the underlying architecture, it can be readily applied across magnetometer technologies, opening the way to practical low-frequency sensing for applications from brain activity mapping to undersea navigation and biomedical diagnostics.
Cite
@article{arxiv.2603.23944,
title = {Ultrawide Bandwidth Optomechanical Magnetometry Using Flux Concentration},
author = {Benjamin J. Carey and Nathaniel Bawden and Fernando Gottardo and James S. Bennett and Douglas Bulla and Scott Foster and Warwick P. Bowen},
journal= {arXiv preprint arXiv:2603.23944},
year = {2026}
}