Accurate and fast measurement of alkali-metal and noble-gas atoms spin polarizability based on frequency response in SERF co-magnetometer

Accurate and fast measurement of the spin polarizability of alkali-metal and noble-gas atoms in co-magnetometer is essential to improve the sensitivity of ultra-sensitive inertial measurements. We establish a frequency response model of K-Rb-21Ne spin strongly coupled ensembles, based on this we present a method for simultaneously measuring the spin polarization of 21Ne and Rb atoms. By applying magnetic field in y-direction oscillating at a fixed frequency, the z-axis main magnetic field value is changed linearly at the same time, the polarizability of Rb and 21Ne spins can be simultaneously obtained. The experimental results were highly consistent with analytical results. By applying a gradient magnetic field to amplify the effect of atomics depolarization, the selfcompensating magnetic field points and atomic ensemble polarizability were measured three times continuously using our method and another method. The results proved that this method has fast measurement speed, high accuracy, and low influence on spin polarisation.