Sinusoidal Noise Suppression in SERF Co-magnetometers with Allan Variance Validation

Spin-exchange relaxation-free (SERF) co-magnetometers, characterized by high sensitivity, compactness, and low drift, show great potential in quantum precision measurements based on atomic ensembles. However, periodic fluctuation noise-originating from laser intensity instability, heating signal crosstalk, and electronic interference-induces oscillatory artifacts in Allan variance analysis, degrading measurement accuracy and long-term stability. This study presents a periodic noise suppression scheme based on jointly optimized finite impulse response (FIR) notch filters, implemented for the first time in a SERF co-magnetometer. By precisely shaping the amplitude response through least-squares optimization, the scheme achieves targeted attenuation of interference frequencies. Experimental results confirm that the proposed method effectively suppresses periodic noise, yielding smoother Allan variance curves and significantly enhancing measurement stability. The proposed approach offers a practical and generalizable solution for improving the precision of atomic sensors and provides technical guidance for noise mitigation in broader precision measurement applications.