Spin projection noise and the magnetic sensitivity of optically pumped magnetometers
Abstract
Present protocols for obtaining the ultimate magnetic sensitivity of optically pumped magnetometers (OPMs) utilizing alkali-metal ensembles rely on uncorrelated atoms in stretched states. A new approach for calculating the spin projection noise (SPN)-limited signal to noise ratio (SNR) and the magnetic sensitivity of OPMs is proposed. Our model is based solely on the mean-field density matrix dynamics and in contrast to previous models, it applies to both low and high field regimes, it takes into account the degree of spin polarization, the intra- and interhyperfine correlations, the decoherence processes, the atom-light coupling and the effects of the spin dynamics on the spin-noise spectra. Fine tuning of the probe frequency allow us to explore different hyperfine states and ground-state correlations. Especially in the spin-exchange-relaxation-free (SERF) regime, alongside the magnetic resonance narrowing and the increased number density, hallmarks of SERF magnetometers, we report on a new SERF feature; the reduction of spin-projection noise at the spin precession frequency as a consequence of strongly-correlated hyperfine spins that attenuate and redistribute SPN when properly probed.
Keywords
Cite
@article{arxiv.2402.10746,
title = {Spin projection noise and the magnetic sensitivity of optically pumped magnetometers},
author = {K. Mouloudakis and V. Koutrouli and I. K. Kominis and M. W. Mitchell and G. Vasilakis},
journal= {arXiv preprint arXiv:2402.10746},
year = {2024}
}