Abstract
The hybrid optical pumping spin exchange relaxation free (SERF) atomic magnetometers can realize ultrahigh sensitivity measurement of magnetic field and inertia. We have studied the 85Rb polarization of two types of hybrid optical pumping SERF magnetometers based on 39K-85Rb-4He and 133Cs-85Rb-4He respectively. Then we found that 85Rb polarization varies with the number density of buffer gas 4He and quench gas N2, pumping rate of pump beam and cell temperature respectively, which will provide an experimental guide for the design of the magnetometer. We obtain a general formula on the fundamental sensitivity of the hybrid optical pumping SERF magnetometer due to shot-noise. The formula describes that the fundamental sensitivity of the magnetometer varies with the number density of buffer gas and quench gas, the pumping rate of pump beam, external magnetic field, cell effective radius, measurement volume, cell temperature and measurement time. We obtain a highest fundamental sensitivity of 1.5073 aT/Hz1/2 (1 aT = 10−18T) with 39K-85Rb-4He magnetometer between above two types of magnetometers when 85Rb polarization is 0.1116. We estimate the fundamental sensitivity limit of the hybrid optical pumping SERF magnetometer to be superior to 1.8359 × 10−2aT/Hz1/2, which is higher than the shot-noise-limited sensitivity of 1 aT/Hz1/2 of K SERF atomic magnetometer.
Highlights
The formula describes that the fundamental sensitivity of the magnetometer varies with the number density of buffer gas and quench gas, the pumping rate of pump beam, external magnetic field, cell effective radius, measurement volume, cell temperature and measurement time
We obtain a general formula on the fundamental sensitivity of the hybrid optical pumping spin exchange relaxation free (SERF) magnetometer, which describes the fundamental sensitivity of the magnetometer varying with the number density of buffer gas and quench gas, pumping rate of pump beam, external magnetic field, cell effective radius, measurement volume, cell temperature and measurement time
We have investigated two types of hybrid optical pumping SERF atomic magnetometers based on 39K (133Cs)-85Rb-4He (39K (133Cs)-85Rb-4He magnetometers), found the fundamental sensitivity of 133Cs-85Rb-4He magnetometer is lower than the one of 39K-85Rb-4He magnetometer at the same cell temperature and in the SERF regime when the pumping rate of pump beam is bigger than about 1916 s−1 and N2 number density is bigger than about 1.974×1016 cm-3 at our chosen conditions
Summary
The formula describes that the fundamental sensitivity of the magnetometer varies with the number density of buffer gas and quench gas, the pumping rate of pump beam, external magnetic field, cell effective radius, measurement volume, cell temperature and measurement time. We obtain a general formula on the fundamental sensitivity of the hybrid optical pumping SERF magnetometer, which describes the fundamental sensitivity of the magnetometer varying with the number density of buffer gas and quench gas, pumping rate of pump beam, external magnetic field, cell effective radius (the shape of the cell is roughly spherical), measurement volume, cell temperature and measurement time. Among 39K, 85Rb and 133Cs SERF magnetometers, there is a maximum temperature range for 39K to make the magnetometer in the SERF regime with the number density of 39K satisfies the condition of the SERF regime, so the SERF magnetometer based on 39K is suitable for an environment with the temperature varying drastically These findings optimize the parameters for the SERF regime, and provide an experimental guide for the design of the hybrid optical pumping SERF magnetometer
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