Investigation on the methods to extend the transverse relaxation time of polarized alkali atoms

In order to improve the sensitivity of radio-frequency atomic magnetometer, two methods to extend the transverse relaxation time of polarized alkali atoms are investigated. One way is the application of a non-relaxing coating, another way is the introduction of buffer gas into cell. A theory relaxation model is built, and the dependences of transverse relaxation time on buffer gas pressure, laser power, cell temperature, and magnetic-field gradient are obtained. The measurements of transverse relaxation time are carried out in a cesium atomic radio-frequency magnetometer. The optical experiment conditions which yield the highest sensitivity are determined in experiments. Experiments results indicate that the optimal pressure for neon is 200 Torr. The experimental results are in agreement with the theoretical ones. An ultimate sensitivity of 100 fT/Hz1/2 of the cesium atomic radio-frequency magnetometer has been achieved. This study helps further optimization of the cell performance and the sensitivity of radio-frequency atomic magnetometer.