单量子态氦原子的制备和精密测量

项目名称： 单量子态氦原子的制备和精密测量

项目编号： No.11304303

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 数理科学和化学

项目作者： 孙羽

作者单位： 中国科学技术大学

项目金额： 30万元

中文摘要： 氦原子是最基本的多电子原子，其精密光谱一直是检验束缚态系统量子电动力学理论的重要手段，通过比对氦原子理论计算和实验测量的结果，可以得到精细结构常数α、以及4^He与其同位素3^He原子核半径等基本物理参数。目前对于三重态能级精细结构分裂的实验测量和理论计算结果间存在kHz水平的偏离，亟待新的独立高精密光谱测量进行检验。实验中的关键是获得足够高的测量信噪比、以及排除外界电磁环境等产生的系统偏差。本项目计划利用激光横向冷却和二维磁光囚禁的方法，获得高亮度、单量子态的氦原子束流，提高实验测量信噪比，通过精密的电磁屏蔽，减小系统偏差的影响，实现亚kHz水平的氦原子精密光谱测量，最终实现在该原子系统中对量子电动力学的检验，及精细结构常数和氦核结构参数等重要物理学量的测量。

中文关键词： 量子电动力学；精细结构常数；精密光谱；精细结构分裂；

英文摘要： Quantum electrodynamic theory(QED) of the simplest bound-three-body system is now stringently tested by precise spectroscopic frequency measurements in helium. Alternatively, comparison between Helium measurements and theory could be used for accurate determination of some fundamental quantities, as for example, the fine structure constant α, and the differenced of nuclear charge radii between two 3^He and 4^He. The obvious discrepancy between the available experimental and theoretical values of the helium triple-state fine structure splitting demands new precise measurements. However, the difficulty of the precise measurements includes both to obtain a high signal-to-noise ratio measurement, and to exclude the impact of the external environment and the systematic error. Compared with other Group's measurement, in order to minimizing the systematic error and improving the accuracy of the experiment measurements,the present project plans to use the method of laser cooling to obtain a high brightness, single quantum state of the helium atoms beam. Ultimately Sub-kHz precision spectroscopy measurement of helium atoms will be made, and the results will potentially lead to the inspection of the fundamental quantum electrodynamics theory, and the associated important physics quantities determination.

英文关键词： Quantum Electrodynamics；Fine Structure Constant；Precise Spectroscopy；Fine Structrue Splittings；