Closed-Loop Control of Compensation Point in the K−Rb−21Ne Comagnetometer

We investigate the real-time closed-loop control of the compensation point in a K-Rb-21Ne 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. The demonstration of closed-loop control of the magnetic field in the single nuclear species comagnetometer is of great significance for rotation sensing such as in gyroscopes and other high-precision metrology applications of the comagnetometer.