Spin noise spectroscopy of an alignment-based atomic magnetometer

TL;DR

This paper presents experimental spin noise spectroscopy of an alignment-based atomic magnetometer and introduces a stochastic model that accurately predicts its noise spectra, enhancing real-time magnetic sensing capabilities.

Contribution

The work experimentally characterizes an alignment-based magnetometer's noise and proposes a predictive stochastic model for its spectral features, advancing magnetometer technology.

Findings

Model accurately predicts spectral peak heights and line-widths.

White noise influences the noise power spectra.

Alignment-based magnetometers can be used for real-time sensing.

Abstract

Optically pumped magnetometers (OPMs) are revolutionising the task of magnetic-field sensing due to their extremely high sensitivity combined with technological improvements in miniaturisation which have led to compact and portable devices. OPMs can be based on spin-oriented or spin-aligned atomic ensembles which are spin-polarized through optical pumping with circular or linear polarized light, respectively. Characterisation of OPMs and the dynamical properties of their noise is important for applications in real-time sensing tasks. In our work, we experimentally perform spin noise spectroscopy of an alignment-based magnetometer. Moreover, we propose a stochastic model that predicts the noise power spectra exhibited by the device when, apart from the strong magnetic field responsible for the Larmor precession of the spin, white noise is applied in the perpendicular direction aligned with the pumping-probing beam. By varying the strength of the noise applied as well as the linear-polarisation angle of incoming light, we verify the model to accurately predict the heights of the Larmor-induced spectral peaks and their corresponding line-widths. Our work paves the way for alignment-based magnetometers to become operational in real-time sensing tasks.