Attosecond and Strong Field Physics in Correlated Multielectron System

在产生阿秒光脉冲方面的惊人进展，以及近红外区域高强度激光器的可用性，为复杂系统中实时电子动力学的研究开辟了一个新的可能性领域。阿秒和强场物理学的目标之一是在自然时间尺度上获取电子运动的基本信息，并能够控制分子中的电荷迁移，例如，在分子位点选择特定的键断裂，或触发化学反应。该项目的主要目标是开发一种新的、高效的、通用的数值方法，以支持多电子系统与超短强激光脉冲相互作用的实验和理论研究。这项工作旨在促进原子化学的发展，并最终弥合阿秒物理学和生物学之间的差距。此外，由于将实验测量结果与实时有意义的物理观测结果联系起来远非易事，因此将研究新的方法来跟踪分子中不同价壳层发射的光电子的快速动力学，以及在强激光场中的隧道电离过程。随着阿秒物理学成为最蓬勃发展的科学领域之一，需要新的理论工具来支持复杂系统中阿秒现象的探索。ATTOMESA是一种新的超快物理数值方法，将被设计用于处理现有实验装置所研究的各种多光子过程，并研究原子和分子中驱动多电子阿秒和强场动力学的未探索方面。在ATTOMESA中使用的形式包括电子相关和交换，以及通道间耦合。它基于一种混合正交方法，其中在短程到中程电子-分子相互作用区域使用高斯型轨道的量子化学描述，而有限元离散变量表示函数补充了更大电子半径的描述，从而产生了一种高效的并行从头算方法，能够处理分子中的强场过程。因此，高谐波产生和隧道电离等过程可以完全从头开始处理。在这项工作中，将使用ATTOMESA处理以下物理过程；利用新的光谱学方法研究了库珀最小值附近和不同价壳层之间的光离时间延迟，估计了生物分子在突然光离后的电子相干性，最后评估了电子相关在条纹/阿托钟实验中的作用。最后，波希米亚力学将被用作解释原子中的强场现象的有用工具。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The astonishing advances in the generation of attosecond light pulses, and the availability of high-intensity lasers in the near-infrared region, have opened up a field of new possibilities in the study of the real-time electron dynamics in complex systems. One of the goals of attosecond and strong-field physics is to access fundamental information on electronic motion in its natural time scale and be able to control charge migration in molecules, e.g., to select a specific bond breaking at a molecular site, or to trigger a chemical reaction. The main objective of the project is to develop a new, efficient, and versatile numerical method to support the experimental and theoretical study of the interaction of multi-electron systems with ultra-short and intense laser pulses. This work aims at contributing to the development of attochemistry and ultimately bridge the gap between attosecond physics and biology. In addition, as connecting experimental measurements to real-time meaningful physical observables has shown to be far from simple, new methods will be investigated to track the rapid dynamics of photoelectron emitted from different valence shells in molecules, as well as during tunnel ionization in intense laser fields. With attosecond physics becoming among the most thriving fields of science, new theoretical tools are needed to support the exploration of attosecond phenomena in complex systems. ATTOMESA, a new numerical method for ultrafast physics, will be designed to treat various multiphoton processes investigated with current experimental setups, and to study unexplored aspects of driven multielectron attosecond and strong field dynamics in atoms and molecules. The formalism used in ATTOMESA includes electron correlation and exchange, as well as inter-channel coupling. It is based on a hybrid quadrature approach, where a quantum-chemistry description using Gaussian-type orbitals is used in the short-range to mid-range electron-molecule interaction region, while finite-element discretized variable representation functions complement the description at larger electronic radius, resulting in a highly efficient parallel ab initio method able to treat strong field processes in molecules. Consequently, processes such as high-harmonic generation and frustrated tunnel ionization can be handled fully ab initio. In this work, the following physical processes will be treated with ATTOMESA; photoionization time delay near a Cooper minimum and between different valence shells using a new spectroscopic method, estimation of electronic coherence in a biomolecule after sudden photoionization, and finally assessing the role of electron correlation in streaking/attoclock experiments. Finally, Bohmian mechanics will be employed as a useful tool to interpret strong-field phenomena in atoms.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.