Low frequency magnetic field suppression in an atomic spin co-magnetometer with a large electron magnetic field

In a K-Rb-Ne-21 co-magnetometer, the Rb electron magnetic field which is experienced by the nuclear spin is about 100 times larger than that of the K in a K-He-3 co-magnetometer. The large electron magnetic field which is neglected in the K-He-3 co-magnetometer coupled Bloch equations model is considered here in the K-Rb-Ne-21 co-magnetometer to study the low frequency magnetic field suppression effect. Theoretical analysis and experimental results shows that in the K-Rb-Ne-21 spin co-magnetometer, not only the nuclear spin but also the large electron spin magnetic field compensate the external magnetic field noise. By comparison, only the He-3 nuclear spins mainly compensate the external magnetic field noise in a K-He-3 co-magnetometer. With this study, in addition to just increasing the magnetic field of the nuclear spins, we can suppress the magnetic field noise by increasing the density of the electron spin. We also studied how the magnetic field suppression effect relates to the scale factor of the K-Rb-Ne-21 co-magnetometer and we compared the scale factor with that of the K-He-3 co-magnetometer. Lastly, we show the sensitivity of our co-magnetometer. The magnetic field noise, the air density fluctuation noise and pumping power optimization are studied to improve the sensitivity of the co-magnetometer.