Here we demonstrate an atomic magnetometer that has a bandwidth of more than 100 kHz and a sensitivity of $180\mathrm{fT/}\surd \mathrm{Hz}$ at a Fourier frequency of 8 Hz, and $0.7\mathrm{nT/}\surd \mathrm{Hz}$ at 100 kHz. These sensitivity measurements are achieved at geophysically useful magnetic field magnitudes (approximately $50\mu \mathrm{T}$ inside a three-layer $\mu$-metal shield) and are limited by the photon shot noise for frequencies above 8 Hz. This device is based on a nonlinear magneto-optical rotation sensor that is operated with an active feedback to the pump modulation frequency. We present a theoretical description of the response functions of the components in the magnetometer. We show that the range of operation of atomic magnetometers can thus be expanded beyond the conventional high-sensitivity, low-bandwidth domain, to provide a high-linearity, high-bandwidth, and high-sensitivity sensor.

• Received 16 October 2020
• Accepted 7 December 2020

DOI:https://doi.org/10.1103/PhysRevApplied.14.064067