Measurements of Majorana Transition Frequency Shift in Caesium Atomic Fountain Clocks

Abstract Caesium atomic fountain clock is a primary frequency standard. During its operation, Majorana transition frequency shift will occur once a magnetic field at some special locations along the atomic trajectory is singular. In this study, by developing a physical model, we analysed the magnetic field requirements for atomic adiabatic transition, and calculated the influence of the Majorana atomic transition on the atomic state via a quantum method. Based on the simulation results of the magnetic field in the fountain clock, we applied the Monte Carlo method to simulate the relationship between the Majorana transition frequency shift and magnetic field at the entrance of magnetic shieldings, as well as the initial atomic population. The measurement of the Majorana transition frequency shift was realized by state-selecting asymmetrically populated atoms. The relationship between the Majorana transition frequency shift and axial magnetic field at the entrance of magnetic shieldings was obtained. The measured results were essentially consistent with the calculated results. Thus, the magnetic field at the entrance of magnetic shield was configured, and the Majorana transition frequency shift of the fountain clock was calculated to be 4.57×10 -18 .