A new method to simultaneously improve the sensitivity and absolute accuracy for CPT magnetometer

This paper proposed a new method to simultaneously improve the sensitivity and absolute accuracy for coherent population trapping (CPT) magnetometer. CPT signals can be measured by scanning the frequency difference of a bichromatic pumping field around the ground-state hyperfine-splitting frequency of ⁸⁷Rb. Meanwhile, the feedback loop can be used to adjust the pump radiation intensity to maintain a constant level of atomic vapour spontaneous fluorescence. This feedback loop improves the resonance contrast greatly. Then the Larmor frequency is determined by differential processing of CPT signals, which can reduce the effects of common-mode noise, nonlinear Zeeman splitting and atomic collisions.