Evaluation And Suppression Of The Magnetic-Induced Rabi Broadening Of Magnetic-Sensitive Ramsey Fringes

Magnetic-sensitive Ramsey fringes are useful for the magnetic field evaluation of atomic fountain clocks. However, broadening mechanisms affect the visibility of the fringes and limit their application for measurement of the magnetic field. The magnetic-induced Rabi broadening, which comes from the magnetic field inhomogeneity in the microwave cavity of fountain clocks and results in the visibility reduction of the fringes, is demonstrated in this paper. Furthermore, an improved method to shorten the Rabi interaction time is proposed to suppress the broadening effect. Experiments are conducted on the rubidium 87 atomic fountain clock to test the broadening mechanism as well as to demonstrate the effectiveness of the improved method to suppress the broadening effect. As a result, we obtain magnetic-sensitive Ramsey fringes and evaluate the average magnetic field. The second-order Zeeman frequency shift also is evaluated with a fractional frequency shift of 1.295 x 10(-13), and a frequency uncertainty of 3 x 10(-16). (C) 2021 Optical Society of America