Identification and Analysis of Thermal–Magnetic Coupling Noise in SERF Comagnetometer

The ultrahigh sensitivity of spin-exchange relaxation-free (SERF) magnetometers and comagnetometers plays a crucial role in tests of fundamental physics, biomagnetic measurement, and quantum navigation. The high-atomic number density is essential for achieving the SERF regime, making the heating system an indispensable component. However, thermal–magnetic coupling noise generated by the heating system represents a primary source of perturbation for precision measurement based on a thermal atomic ensemble. We identify the main sources of thermal–magnetic coupling noise based on a K-Rb-²¹Ne SERF comagnetometer. By optimizing the operating mode of the heating system, the low-frequency noise at 0.5 Hz is improved by approximately one order of magnitude, thereby enhancing the low-frequency sensitivity of the SERF comagnetometer. Our research advances the long-term stability of atomic sensors and supports their application in probing new physics beyond the standard model in the low-energy regime.