Intense Laser-Atom Physics in Scaled Interactions

孤立原子与强电磁场的相互作用是原子、分子和光学物理学中一个前沿问题的基础。通过吸收许多光子将大量光能耦合到原子中的能力提出了许多有趣的问题，并导致了许多新发现，如阈值以上电离、高谐波产生、多重电离和绝热稳定。问题的核心是原子对激光脉冲的非扰动响应，激光脉冲施加的外场与将电子束缚在原子核上的力相当。该项目对新型相互作用条件下的单原子响应进行了全面的研究，这不仅将提供标度定律和理论的基本测试，而且还将产生将前所未有的能量耦合到单个原子中的能力。该项目的总体目标是通过在单光子能量与原子结合能相比极小的情况下利用强场相互作用的波长缩放来扩大实验研究的范围。强场相互作用的各个方面都具有隐含的波长依赖性，这是一个关键的缩放参数，尚未以系统的方式探索或利用。人们对这个基本原子物理问题的持续兴趣源于它在其他物理和技术领域的广泛影响。单原子响应是等离子体、惯性约束聚变概念、先进粒子加速和天体物理学中更复杂现象的初始条件。强烈的激光-原子相互作用本身为短波长科学、量子控制和推进超高速电子物理学的新兴学科——光子物理学开辟了新的机会。最近，用于这些研究的产生超快激光脉冲的光学技术已经达到了可以完全确定电磁场的复杂程度。此外，这项研究的跨学科性质加上最先进的超快光学技术，为本科生、研究生和博士后研究人员提供了一个极好的培训场所。

The interaction of an isolated atom with an intense electromagnetic field is the basis for one of the forefront problems in atomic, molecular and optical physics. The ability to couple large amounts of light energy into an atom by the absorption of many photons poses many intriguing questions and has led to many new discoveries such as above-threshold ionization, high-harmonic generation, multiple ionization and adiabatic stabilization. At the core of the problem is the non-perturbative response of the atom to a laser pulse that imposes an external field comparable to the forces binding the electrons to the nucleus. This project undertakes a comprehensive study of the single atom response under novel interaction conditions that will not only provide basic tests of scaling laws and theory but also result in the ability to couple an unprecedented amount of energy into a single atom. The project's overall objective is to broaden the scope of experimental investigations by utilizing the wavelength scaling of the strong field interaction in the regime where the single-photon energy is extremely small compared to the atomic binding energy. Various aspects of the strong-field interaction have an implicit wavelength-dependence that is a crucial scaling parameter and has not been explored or exploited in a systematic fashion.The continuing interest in this fundamental atomic physics problem is derived from its broad implications in other areas of physics and technology. The single atom response is the initial condition of more complex phenomena found in plasmas, inertial confined fusion concepts, advance particle acceleration and astrophysics. The intense laser-atom interaction itself is opening new opportunities in short wavelength science, quantum control and advancing an emerging discipline in hyperfast electron physics, attophysics. Recently, the optical techniques used for producing the ultra-fast laser pulses for these studies have reached a level of sophistication where the electromagnetic field can be completely determined. Furthermore, the interdisciplinary nature of this research coupled with state-of-the-art ultra-fast optical technology provide an excellent training ground for both undergraduate, graduate students and post-doctoral research associates.