Magnetic Field Measurement Based On A Rubidium-xenon Vapor Cell Atomic Magnetometer

Magnetic fields are widely found in nature.The precise measurement of weak magnetic fields is not only widely used,but also promotes the progress and develop-ment of many research fields.With the rapid development of quantum control and pho-todetection technology,research on experimental devices for ultra-sensitive detection of magnetic fields using atomic spins has become a hot topic.Among them,the Spin Ex-change Relaxation Free(SERF)alkali metal atomic magnetometer becomes the most sensitive magnetic field measuring device,with a sensitivity realizing 0.16 fT/(?).However,due to its working conditions and magnetic field measurement characteris-tics,its use range is limited.Research on the magnetic field measurement capabilities of different types of atomic magnetometers helps to meet different magnetic field mea-surement requirements.In order to study the precise measurement of weak magnetic fields,this paper s-tudies the basic characteristics of the rubidium-xenon vapor cell atomic magnetometer platform developed by the author and his colleagues independently.The content of this paper includes the following two aspects:1)Experimental device basic parameter test.The four-channel noise level of the data acquisition card,the calibration values of the coil coefficient of the shimming and pulse coils in the shielding cylinder device,the ?/2 pulse application method and the gyromagnetic ratio of the 129Xe atoms are given by experimental calibration.The ex-perimental results show that the transverse and longitudinal relaxation time of the hy-perpolarized 129Xe are about 20.6 s and 21.5 s,respectively.The experimental device basic parameter test has important reference functions for the design,evaluation and implementation of the experimental scheme in the later stage of the device.2)Calibration of the magnetic field measurement capability of the experimental device.The experiments calibrate the magnetic field measurement capability of the two magnetic field measurement methods of the rubidium-xenon vapor cell atomic magne-tometer.The first is to measure external magnetic fields by the influence of the external magnetic fields on the polarization of the alkali metal atoms.The results of the exper-iment calibration are given that the sensitivity of the alternate current(AC)magnetic field measurement in the frequency range of 2100 Hz is about 1.5 pT/(?)and the bandwidth is about 2.8 kHz.The second is to measure the external magnetic fields by measuring the Larmor frequency of the hyperpolarized 129Xe in the rubidium-xenon vapor cell.The calibration results of the static magnetic field and the ultra-low fre-quency magnetic field are given that:the static magnetic field measurement precision is 9.4 pT and the measurement range exceeds 50 ?T.The upper frequency limit of the ultra-low frequency magnetic field measurement is 3.93 mHz.At the frequencies of 1 mHz and 2 mHz,the magnetic field measurement limits are 0.392 nT and 0.474 nT,and the frequency resolution values are lower than 0.026 mHz and 0.039 mHz,respectively.The rubidium-xenon vapor cell atomic magnetometer realizes the measurement of static magnetic field,ultra-low frequency AC magnetic field and higher frequency(compared to the bandwidth of SERF atomic magentometers)AC magnetic field.It has different magnetic field measurement characteristics from SERF atomic magnetometer and has broad application prospects.