Ultimate parameters of an all-optical MX resonance in Cs in ultra-weak magnetic field

TL;DR

This paper investigates the parameters of an all-optical MX resonance in cesium within ultra-weak magnetic fields, optimizing sensitivity for magnetoencephalography and demonstrating significant sensitivity improvements.

Contribution

It introduces optimized resonance parameters and a semi-empirical model for spin-exchange broadening effects in all-optical MX sensors.

Findings

Achieved over fourfold sensitivity improvement, reducing from 13 to 3 fT/Hz^{1/2}.

Demonstrated effects of incomplete suppression of spin-exchange broadening.

Optimized resonance parameters for maximum sensitivity in magnetoencephalographic sensors.

Abstract

We present the results of studying the parameters of the magnetic MX resonance in an all-optical sensor built according to the two-beam Bell-Bloom scheme in nonzero ultra-weak magnetic fields in which the effects of spin-exchange broadening suppression are partially manifested. We report on the features of the resonance under these conditions. We also optimize the resonance parameters to achieve maximum sensitivity in magnetoencephalographic sensors. We demonstrate an improvement in the ultimate achievable sensitivity of an all-optical MX sensor by a factor of four or more, which in our experiment corresponds to a decrease from 13 to 3 fT/Hz1/2 in a volume of 0.13 cm3. We also report the effect of incomplete suppression of spin-exchange broadening under conditions of strong transverse modulated optical pumping, and propose a semi-empirical model to describe it.