The review meeting of the Chinese Academy of Sciences (CAS) project “High-Precision Atom Interferometer for the Test of the Equivalence Principle” was held at the Wuhan Institute of Physics and Mathematics (WIPM) on December 21-22, 2010. The meeting, organized by the Bureau of Planning and Finance of CAS, included experts and leaders from the Shanghai Institute of Optics and Fine Mechanics (SIOM), the CAS, the National Institute of Metrology (NIM), Huazhong University of Science and Technology (HUST), Wuhan University, and Huazhong Normal University.  After carefully listening to Professor Wang Jin’s report on completed tasks and financial affairs, the group of experts had a lively discussion, offering valuable advice and suggestions.

The “High-Precision Atom Interferometer for the Test of the Equivalence Principle” project uses many advanced techniques such as ultrahigh vacuum, magnetic shielding, laser systems, magneto-optical trapping, and atom fountains. The implementation scheme is innovative.  After more than 3 years, the research group has conquered a large number of difficulties and accomplished a series of tasks, including designing the experiment and machining, installing and testing the equipment. Beginning on April 28th, 2010, the whole apparatus was installed and tested in the Atomic Frequency Standards Building.  About 8 months later, the debugging was accomplished. During a live test by 3 experts, the height of the atom fountain was measured to be 6 m, and the contrast ratio of the atom interferometer fringe was measured to be 76%. Therefore, the main technical criteria have reached the required targets, and a high-precision atom interferometer has been successfully achieved at WIPM. The height of the apparatus is 12.6 m and the designed height of the atom fountain is 10 m, which makes it the highest atom interferometer in the world.

 

The experts agree that this apparatus provides a research platform for precision gravity measurement and the test of the Equivalence Principle via observing the free-falling atoms.

The proposal to construct a 10-meter high-precision atom interferometer in Wuhan was first advanced during the scientific development conference in WIPM in May 2007.  The project was approved and carried out, starting in October 2007. The project was supported by the scientific apparatus research department of the CAS, the preferential arrangement initiative of WIPM, and the important apparatus research department of the National Natural Science Foundation of China.