High-precision measurement of absolute gravity is very important in Geophysics, Geodesy, Hydrology, Seismology, etc. It is difficult to evaluate the accuracy of an absolute gravimeter (AG) by itself, since the local absolute gravity value is always changing with time and position. Therefore, the comparison between different high-precision absolute gravimeters is of great importance for the evaluation of the instrument accuracy.

Researchers from Zhejiang University of Technology and Zhejiang University reported their compact cold atom gravimeter (CCAG) for participating in the first Asia-Pacific Comparison of Absolute Gravimeters (APMP.M.G-K1), which was the first CCAG participating in a Regional Absolute Gravity Comparison in China. The principle of the CCAG is based on the matter wave interference. The test mass in the CCAG is the microcosmic atoms rather than the classic object, which makes the CCAG more suitable for the continuous gravity monitoring. The accuracy of this gravimeter was evaluated to be about 19 μGal after the correction of the main systematic errors. The sensitivity was estimated to be 90 without any vibration isolation system during measurement. This work has been published in Chinese Optics Letters, Volume 17, Issue 1, 2019 (Zhijie Fu, et al., Participation in the absolute gravity comparison with a compact cold atom gravimeter).

Professor Qiang Lin, director of the group, believes that there are still spaces to improve the absolute accuracy of the CCAG. The successful participation and measurement of the CCAG in the APMP.M.G-K1 provides valuable experiences for the improvement of this kind of gravimeter.

Based on the comparison results, further work will be focused on the improvement of accuracy and the suppression of systematic noises.

A compact cold atom gravimeter participating in the Comparison of Absolute Gravimeters.