In Ramsey interference of the clock transition of cold sodium atoms, we observed dephasing of the visibility, which was based on the frequency fluctuation due to the second-order Zeeman effect for inhomogeneity of the magnetic field within the atomic cloud. The frequency fluctuation was enhanced with increased strength of the quantization magnetic field, causing the dephasing of the visibility to become large. The theoretical dephasing function with frequency fluctuation was in good agreement with experimental values.

Abstract:In a Ramsey atom interferometer excited by two electromagnetic fields, if atoms are under a time-varying scalar potential during the interrogation time, the phase of the Ramsey fringes shifts owing to the scalar Aharonov-Bohm effect. The phase shift was precisely examined using a Ramsey atom interferometer with a two-photon Raman transition under the second-order Zeeman potential, and a formula for the phase shift was derived. Using the derived formula, the frequency shift due to the scalar Aharonov-Bohm effect in the frequency standards utilizing the Ramsey atom interferometer was discussed.