Indirect pumping bell–bloom magnetometer**Project supported by the Natural Science Foundation of Shanghai (Grant No. 16ZR1402700), the National Natural Science Foundation of China (Grant No. 91636102), and the National Key Research and Development Program of China (Grant No. 2016YFA0302000).

Abstract

When the ground state hyperfine splitting of alkali metal vapor atoms is well optically resolved, the spin coherence on one hyperfine sublevel can be generated directly or indirectly by pumping the same or the other sublevel respectively. We experimentally studied the pump power dependence of the field response of a Bell-Bloom magnetometer for the two pumping schemes in a paraffin coated 87Rb vapor cell. We find that although the maximum field response is achieved by combining the two pumping schemes, indirect pumping alone can do nearly as good while being much simpler to operate. We have achieved a sensitivity of 100 fT/Hz1/2 with a single indirect pump at room temperature.