Real-time nondemolition measurement method for alkali vapor density and its application in a spin-exchange relaxation-free co-magnetometer

This study presents a novel method for measuring the number density of K in K-Rb hybrid vapor cells using circularly polarized pump light on polarized alkali metal atoms. This proposed method eliminates the need for additional devices such as absorption spectroscopy, Faraday rotation, or resistance temperature detector technology. The modeling process involved considering wall loss, scattering loss, atomic absorption loss, and atomic saturation absorption, with experiments designed to identify the relevant parameters. The proposed method is real-time, highly stable, and a quantum nondemolition measurement that does not disrupt the spin-exchange relaxation-free (SERF) regime. Experimental results demonstrate the effectiveness of the proposed method, as the longitudinal electron spin polarization long-term stability increased by 204% and the transversal electron spin polarization long-term stability increased by 44.8%, as evaluated by the Allan variance. & COPY; 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

This study presents a novel method using circularly polarized pump light on polarized alkali metal atoms to measure the number density of K in K-Rb hybrid vapor cells. This method eliminates the need for additional devices such as absorption spectroscopy, Faraday rotation, or resistance temperature detector technology. The proposed method is real-time, highly stable, and a quantum nondemolition measurement that does not disrupt the SERF regime. Experimental results demonstrate its effectiveness in increasing the long-term stability of electron spin polarizations.