Phase-error-free atomic magnetometer and vector measurement method based on demodulated signal phase in geomagnetic environment

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The performance of double-beam atomic magnetometer in the geomagnetic environment is greatly affected by the vectorial direction of magnetic field, which leads to the shift of the phase of the demodulation signal. We propose a phase-error-free scalar double-beam atomic magnetometer. When the RF field is along the direction of probe beam, the fluctuation of the phase of the demodulation signal can be avoided. For the practical measurement environment, we propose a phase extraction method for atomic magnetometer. Additionally, based on the phase of the demodulated signal when the RF field is applied in the directions of pumping, probing, and perpendicular to the pumping-detection plane, we propose a method for vector magnetic field measurement. The measurement results indicate that under a 10 μT bias magnetic field, the deviations θ and φ are within 0.1°. The theory and method proposed are of great significance to the application of magnetometer in geomagnetic magnetic field.