Characterization of the gravity gradiometer based on the Sr optical clock transition

We present a gravity gradiometer with the strontium optical clock transition by integrating a double lattice launch technique to develop two atomic samples vertically and a new method to add an artificial phase shift between two samples. We experimentally characterize the launch performance and the robustness of adding the artificial phase shift. The tunable differential phase shift is particularly important for characterizing the performance of a gravity gradiometer when the separation of the two clouds is limited by the geometrical constraints. Moreover, numerical simulation results indicate that the systematic error of the differential phase measurement can be largely reduced when the ellipse phase approaches ±π/2 rad by simply tuning the relative phase between two RF signals.