Source: National Natural Science Foundation of China 

Grant No:91536102 

Project: Precision calculations on the atomic structures and the theoretical research on the external field effects 

Chief Specialist: Prof.Tingyun Shi

Abstract: Precision calculation of the atomic structure and the precise description of the external field response of the atoms are not only the important parts in the precision measurement physics field, but also the theoretical basis for the analysis of the systematic error budget of the atomic clocks and the test of the theory of quantum electrodynamics (QED) and the fundamental symmetries. In this project, we will perform the calculations on the high order relativistic and QED corrections of the low excited energy levels in helium atom and the light helium-like ions. It is expected that the calculated energy levels could achieve 10 - 12 significant digits and the fine structure split could achieve 8 - 9 significant digits. The laser field response theory for the low excited states in helium atom will be developed in which the relativistic and QED effects will be included. Using this theory, the magic-zero wavelengths (also called tune-out wavelengths) and the magic wavelengths will be precisely determined. Combining the results of the ongoing experiment on helium atom in Australian National University, we could conduct the high-precision test on the theory of QED. We will also develop the high-precision relativistic atomic structure theory for the multi-electron atoms, calculate their response on the external fields, explore the precision-measurement experimental schemes on the candidates of the atomic clocks and the atomic parity nonconservation research. The research of this project will be great importance for the test of the three-body bound QED theory , the experimental determination of the fine structure constant, the measurement of the nuclear charge radii, and the precision-measurement experiment design based on the optical clocks.