近日，美国中佛罗里达大学的Luca Argenti及其研究小组与美国加州大学的C. William McCurdy等人合作并取得一项新进展。经过不懈努力，他们揭示氖双光子阿秒双电离中的双电子干涉。相关研究成果已于2024年7月2日在国际知名学术期刊《物理评论A》上发表。

最近，该研究团队将虚拟序列模型扩展到任意光脉冲。这种扩展采用多通道散射状态，用于中性和电离靶的单电离，研究人员最初应用于氦。在目前的研究中，研究表明，该扩展虚拟序列模型再现了角度集成可观测值的定性特征，并提供了氖的实验结果，这是一个相当复杂的目标。与氦相比，研究人员观察到氖的联合能量分布中有一个有趣的反向双粒子干涉特征。这一现象是由于与两个光电子耦合的三重态对称的最终双电离态的存在，用目前的实验技术应该是可以观察到的。

据悉，利用x射线自由电子激光器(XFEL)实现的泵浦探测实验将使人们能够通过检测重合的光电子对，在阿秒时间分辨率下直接观察相关的电子运动。在氦中，双光子双电离(TPDI)的非有序态和有序态之间的跃迁可以用一个虚拟有序态模型很好地解释。然而，对于更复杂的原子中的TPDI过程，人们所知甚少。

附：英文原文

Title: Two-electron interference in two-photon attosecond double ionization of neon

Author: Siddhartha Chattopadhyay, Carlos Marante, Barry I. Schneider, C. William McCurdy, Luca Argenti

Issue&Volume: 2024/07/02

Abstract: The pump-probe experiments enabled by x-ray free-electron lasers (XFEL) will allow us to directly observe correlated electronic motion with attosecond time resolution by detecting photoelectron pairs in coincidence. In helium, the transition between the nonsequential and sequential regime in two-photon double ionization (TPDI) is well explained by a virtual-sequential model. Much less is known, however, about the TPDI process in more complex atoms. Recently, we extended the virtual-sequential model to arbitrary light pulses [Chattopadhyay et al. Phys. Rev. A 108, 013114 (2023)]. This extension employs multichannel scattering states for the single ionization of both the neutral and the ionized target, which we initially applied to helium. In the present study, we show that our extended virtual-sequential model reproduces the qualitative features of the angularly integrated observables with available experimental results for neon, a considerably more complex target. We observe an intriguing feature of inverted two-particle interference in the joint-energy distribution of Ne compared to He. This phenomenon, attributable to the presence of a final doubly ionized state with triplet symmetry coupled to the two photoelectrons, should be observable with current experimental technologies.

DOI: 10.1103/PhysRevA.110.013106

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.013106