# Closed-loop Control of Compensation Point in the K-Rb-$^{21}$Ne Comagnetometer

## TL;DR

This paper demonstrates a novel closed-loop control method for the compensation point in a K-Rb-$^{21}$Ne comagnetometer, enhancing stability and measurement range for high-precision applications.

## Contribution

It introduces the first real-time closed-loop control of magnetic field in a single nuclear species comagnetometer, improving stability and accuracy.

## Key findings

- Enhanced systematic stability of the comagnetometer
- Increased linear measuring range
- Suppressed cross-talk error

## Abstract

We investigate the real-time closed-loop control of compensation point in the K-Rb-$^{21}$Ne comagnetometer operated in the spin-exchange relaxation-free regime. By locking the electron resonance, the alkali metal electrons are free from the fluctuations of the longitudinal ambient magnetic field and nuclear magnetization, which could improve the systematic stability, enlarge the linear measuring range, and suppress the cross-talk error of the comagnetometer. This is the first demonstration of closed-loop control of magnetic field in the single nuclear species comagnetometer, which will be of great significance for rotation sensing as gyroscopes and other high precision metrology applications of the comagnetometer.