Investigation of the fine structure of antihydrogen
Investigation of the fine structure of antihydrogen
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DOI：
10.1038/s41586-020-2006-5
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发表时间：
2020-02-01
期刊：
影响因子：
64.8
通讯作者：
Wurtele, J. S.
中科院分区：
文献类型：
--
作者：
Ahmadi, M.;Alves, B. X. R.;Wurtele, J. S.
在1947年具有历史意义的谢尔特岛量子力学基础会议上，威利斯·兰姆报告了氢原子精细结构中一个意想不到的特征：2S（1/2）和2P（1/2）态的分离。这种分离的观察，现在被称为兰姆位移，标志着现代物理学发展中的一个重要事件，激励其他人发展量子电动力学理论（2-5）。量子电动力学也描述了反物质，但直到最近才有可能合成和捕获原子反物质以探测其结构。现代反原子测量反映了二十世纪量子原子物理学的历史发展，为测试量子电动力学和标准模型的基本对称性提供了一种独特的方法。在这里，我们报告了n = 2状态下反氢（氢原子的反物质对应物）精细结构的测量结果。利用反氢(6)中1S-2P莱曼- α跃迁的光学激发，我们确定了它们在1特斯拉磁场中的频率，精度达到十亿分之十六。假设标准的塞曼和超精细相互作用，我们推断出反氢中的零场精细结构分裂(2P（1/2)-2P(3/2)）。结果值与量子电动力学的预测一致，精度为2%。使用我们之前测量的1S-2S跃迁频率值（6,7），我们发现反氢中的经典兰姆位移(2S（1/2)-2P（1/2）在零场分裂）与理论在11%的水平上是一致的。我们的观察代表了对反氢光谱中的精细结构和兰姆位移的精确测量的重要一步，作为电荷-奇偶-时间对称性的测试(8)，以及对其他基本量的确定，如反质子电荷半径（9,10），在这个反物质系统中。考虑到标准塞曼效应和超精细效应，对反氢原子1S-2P跃迁的精确测量证实了量子电动力学的预测。
At the historic Shelter Island Conference on the Foundations of Quantum Mechanics in 1947, Willis Lamb reported an unexpected feature in the fine structure of atomic hydrogen: a separation of the 2S(1/2) and 2P(1/2) states(1). The observation of this separation, now known as the Lamb shift, marked an important event in the evolution of modern physics, inspiring others to develop the theory of quantum electrodynamics(2-5). Quantum electrodynamics also describes antimatter, but it has only recently become possible to synthesize and trap atomic antimatter to probe its structure. Mirroring the historical development of quantum atomic physics in the twentieth century, modern measurements on anti-atoms represent a unique approach for testing quantum electrodynamics and the foundational symmetries of the standard model. Here we report measurements of the fine structure in the n = 2 states of antihydrogen, the antimatter counterpart of the hydrogen atom. Using optical excitation of the 1S-2P Lyman-alpha transitions in antihydrogen(6), we determine their frequencies in a magnetic field of 1 tesla to a precision of 16 parts per billion. Assuming the standard Zeeman and hyperfine interactions, we infer the zero-field fine-structure splitting (2P(1/2)-2P(3/2)) in antihydrogen. The resulting value is consistent with the predictions of quantum electrodynamics to a precision of 2 per cent. Using our previously measured value of the 1S-2S transition frequency(6,7), we find that the classic Lamb shift in antihydrogen (2S(1/2)-2P(1/2) splitting at zero field) is consistent with theory at a level of 11 per cent. Our observations represent an important step towards precision measurements of the fine structure and the Lamb shift in the antihydrogen spectrum as tests of the charge-parity-time symmetry(8) and towards the determination of other fundamental quantities, such as the antiproton charge radius(9,10), in this antimatter system.Precision measurements of the 1S-2P transition in antihydrogen that take into account the standard Zeeman and hyperfine effects confirm the predictions of quantum electrodynamics.