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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=669145
• 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本物理理论的基础试验场。由于最近技术的发展，如飞秒光学梳子，现在很少有物体系统的测量可以达到前所未有的高精度，这为理论家提供了许多令人兴奋的机会，通过对微小但极其重要的效应进行计算来探索基础物理，例如高阶相对论和量子电动力学(QED)效应。通过理论和实验的比较，人们可以检验现有的理论，发现可能的新物理，如破坏基本对称性；还可以通过研究氦的精细结构来提取基本物理常数的精确值，通过研究H2+中两个能级之间的跃迁频率来提取电子-质子质量比，并研究它们的时间变化。在过去的15年里，我们在获得三体和四体原子和分子系统的薛定谔方程的高精度解方面取得了重大进展，这使得我们能够精确地计算相对论和QED效应。我们工作的一个重要应用是与TRIUMF和GSI的两个主要实验小组合作，精确测定晕锂11Li的核电荷半径。为了确定电荷半径，必须高精度地计算与质量有关的同位素位移部分，包括相对论修正和QED修正。虽然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，突破是在2000年，当时我们成功地计算了中性Li跃迁中的质量效应，其不确定度优于百万分之五。我们的方法的意义在于，没有其他方法既独立于核结构模型，又能够产生足够的精度来计算核电荷半径。因此，与我们的结果进行比较，能够区分核力量的各种可能候选者。我们现在可用的高精度理论为开发原本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动我们探索少体原子和分子系统的高阶相对论和QED效应的努力，这将为原子和核物理之间的界面上取得更深刻的进展铺平道路。