Optomechanical magnetometry with a macroscopic resonator

TL;DR

This paper presents a large-scale optomechanical magnetometer capable of detecting very weak magnetic fields in unshielded environments, with potential for femtotesla sensitivity through further improvements.

Contribution

It introduces a centimeter-scale crystalline whispering gallery mode resonator for optomechanical magnetometry, achieving high sensitivity in a non-cryogenic, unshielded setting.

Findings

Peak sensitivity of 131 pT/√Hz achieved

Operates effectively in unshielded, room-temperature environment

Potential for femtotesla sensitivity with further optimization

Abstract

We demonstrate a centimeter-scale optomechanical magnetometer based on a crystalline whispering gallery mode resonator. The large size of the resonator allows high magnetic field sensitivity to be achieved in the hertz to kilohertz frequency range. A peak sensitivity of 131 pT per root Hz is reported, in a magnetically unshielded non-cryogenic environment and using optical power levels beneath 100 microWatt. Femtotesla range sensitivity may be possible in future devices with further optimization of laser noise and the physical structure of the resonator, allowing applications in high-performance magnetometry.