A Magnetometer Suitable for Measurement of the Earth'S Field Based on Transient Atomic Response

We describe the development of a simple atomic magnetometer using 87Rb vapour suitable for monitoring Earth's magnetic field. The magnetometer is based on time-domain determination of the transient precession frequency of the atomic alignment around the measured field. A sensitivity of 1.5 nT Hz−1/2 is demonstrated by the measurement of the Earth's magnetic field in the laboratory, while for a simulated Earth field inside a magnetic shield a 130 pT Hz−1/2 sensitivity was attained. We discuss the various parameters determining the magnetometer precision and accuracy and predict a sensitivity of 30 pT Hz−1/2.