Continuous gravity measurement with a portable atom gravimeter

We report here a portable and robust home-built atom gravimeter (USTC-AG11) continuously working in a seismic station in Zhaotong, Yunnan, for over five months. Based on the principle of matter-wave interference, the atom gravimeter is very sensitive to the local gravity and reaches the precision of micro-Gal ($1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}\mathrm{m}/{\mathrm{s}}^{2}$) level. With the technique of vibrational compensation, the sensitivity of the atom gravimeter reaches $38\phantom{\rule{0.16em}{0ex}}\textmu{}\mathrm{Gal}/\sqrt{\mathrm{Hz}}$, the overall noise level is suppressed by 80% compared to the no-vibration-compensation method, and 95% of the vibration noise is effectively suppressed. The design of the atom gravimeter in the electronics and laser optics, especially the laser frequency and phase auto-relock technology, guarantees long-term continuous running. The long-term precision of the atom gravimeters is better than $2\phantom{\rule{0.16em}{0ex}}\textmu{}\mathrm{Gal}$, which is comparable to the best classical gravimeter FG-5(X). Our work provides an application for the high-precision atomic gravimeter based on modern quantum sensing technology in the field of geophysics and geodesy survey.