High-precision theory of few-body atomic and molecular systems

高精度少体原子分子系统理论

• 批准号: RGPIN-2014-05291
• 负责人: Yan, ZongChao
• 金额: $ 2.62万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567072
• 关键词: precision; theory; few; body; atomic

Few-body atomic and molecular systems, such as H, He, Li, H2+, are fundamental testing grounds for basic physics theories. Due to recent development of techniques, such as femtosecond optical comb, measurements on few body systems can now reach an unprecedented high precision, providing many exciting opportunities for theorists to explore fundamental physics by performing calculations on small but extremely important effects, such as high order relativistic and quantum electrodynamic (QED) effects. Through comparison between theory and experiment, one can test the existing theories and discover possible new physics, such as violation of fundamental symmetries; one can also extract precise values of fundamental physical constants, such as the fine structure constant through the study of helium fine structure, and the electron-proton mass ratio through the study of transition frequency between two energy levels in H2+, and study their variation in time. In the past 15 years, we have made significant advances in obtaining high precision solutions to the Schrodinger equation for three and four body atomic and molecular systems, which allows us to calculate relativistic and QED effects precisely. One of the important applications of our work is the precise determination of the nuclear charge radius of halo lithium, 11Li, in collaboration with two leading experimental groups at TRIUMF and GSI. To determine the charge radius, it is necessary to calculate the mass-dependent part of the isotope shift with high precision, including relativistic and QED corrections. While this has been possible for one and two-electron systems since the 1980's, for Li and Li-like ions, the breakthrough came in 2000 when we succeeded in calculating the mass effect in transitions of neutral Li with an uncertainty of better than 5 parts per million. The significance of our method is that no other method is both independent of nuclear structure models and capable of yielding sufficient accuracy for the nuclear charge radius. Comparisons with our results are therefore capable of distinguishing amongst the various possible candidates for the nuclear forces. Our high precision theory that is now available creates new opportunities to develop measurement tools that would otherwise not exist, and opens up a new area of study at the interface between atomic physics and nuclear physics. This research program will advance our efforts to explore higher-order relativistic and QED effects for few-body atomic and molecular systems by developing new computational methods, which will pave the way to even more profound advances at the interface between atomic and nuclear physics.

H、He、Li、H2+等少体原子和分子体系是基础物理理论的重要实验场。由于最近的技术发展，如飞秒光梳，对少数体系统的测量现在可以达到前所未有的高精度，为理论家提供了许多令人兴奋的机会，通过对小但非常重要的效应进行计算来探索基础物理，如高阶相对论和量子电动力学（QED）效应。通过理论与实验的比较，可以检验现有的理论，发现可能的新物理，如基本对称性的破坏;人们还可以提取基本物理常数的精确值，例如通过研究氦精细结构得到的精细结构常数，以及通过研究H2+中两个能级之间的跃迁频率得到的电子-质子质量比，并研究它们随时间的变化。在过去的15年里，我们在获得三体和四体原子和分子系统薛定谔方程的高精度解方面取得了重大进展，这使我们能够精确地计算相对论和QED效应。我们工作的重要应用之一是与TRIUMF和GSI的两个领先实验组合作，精确测定晕锂11 Li的核电荷半径。为了确定电荷半径，需要高精度地计算同位素位移的质量依赖部分，包括相对论和QED修正。虽然自20世纪80年代以来，这对于单电子和双电子系统是可能的，但对于Li和类Li离子，突破出现在2000年，当时我们成功地计算了中性Li跃迁的质量效应，其不确定性优于百万分之五。我们的方法的意义是，没有其他方法是既独立于核结构模型，并能够产生足够的精度的核电荷半径。因此，通过与我们的结果进行比较，就能够区分各种可能的核力候选者。我们现在可用的高精度理论为开发否则不存在的测量工具创造了新的机会，并在原子物理和核物理之间的界面上开辟了一个新的研究领域。这项研究计划将通过开发新的计算方法来推进我们探索高阶相对论和QED效应的努力，为原子和核物理之间的接口铺平道路。