Accurate optically pumped magnetometer based on Ramsey-style interrogation.

Light-atom interactions during spin preparation and readout in optically pumped magnetometers can lead to inaccuracies. We demonstrate a novel, to the best of our knowledge, detection strategy that exploits an interrogation sequence in the pulsed free-induction-decay modality to suppress these systematic errors. The technique is predicated on monitoring the dynamics of preoriented atomic spins as they evolve unperturbed during a dark interval, by subsequently applying a time-delayed optical pulse to infer the spin state's phase. This detection mode reduced light shift inaccuracies to within 0.6 nT, and could be employed in a wide variety of high-precision atomic magnetometry experiments.