Realization of a gravity gradiometer with a waveguide atom interferometer

Accurate measurement of gravitational force has many important applications, from geophysical exploration to gravitational wave detection. A gravity gradiometer can be used to detect gravitational signatures without vibration noise for these applications. An atom interferometer in free space has been used to develop one of the most sensitive gravity gradiometers. However, the required significant interrogation time results in a considerable free fall distance, making it challenging to create a portable sensor and increase the sensitivity for the most critical applications. Here, we report the realization of a gravity gradiometer with a waveguide atom interferometer with which atoms are guided during the interrogation without free fall. With two separate clouds of Rb atoms on a waveguide, a differential measurement of the acceleration of atoms was made, which can be used to detect gravity gradients along the axial direction of the guide beam. The coherent interrogation time up to 80ms was demonstrated, and a further increase is being investigated by reducing relative phase fluctuations from various sources. The progress of this project will be reported.