Suppression of modulation-magnetic-fields crosstalk for single-beam optically-pumped magnetometers

We propose a feasible method that enables suppression of crosstalk induced by the additional transverse (sinusoidal/noise) magnetic field near the modulation frequency of the arrayed single-beam optically-pumped magnetometers (OPMs), which is usually generated by adjacent channels, by locking the remanence to zero through a closed-loop control. Based on a miniaturized ⁸⁷Rb atomic cell of 3 × 3 × 3 mm, our method can significantly suppress the modulation magnetic field crosstalk. In addition, the magnetic field control circuit structure is optimized by investigating the effect of magnetic field noise on the sensitivity of the magnetometer. The sensitivity of OPM can reach 16fT/Hz^1/2 between 10 and 100 Hz. These crosstalk amplitude results show good agreement with theoretical analysis. Our method is especially advantageous for future high-resolution magnetocardiography and magnetoencephalography systems where dense array with large amount of miniaturized magnetometers are required.