Intense Laser-Atom Physics in Scaled Interactions

激光与物质的基本相互作用为现代基础和应用光学研究提供了基础。最近探测到黑洞碰撞发出的引力波，证实了爱因斯坦的引力理论，这就是对基础研究的影响的例证。这一成就的核心是光学干涉仪探测器。一般来说，干涉仪在探测微小扰动方面具有极高的灵敏度，无论是在空间中传播的引力波，还是在这个项目中探索的原子中电子的微小运动。光与物质的相互作用也被用于为社会提供更多切实利益的应用中，例如非侵入性手术和未来的能源。在这些情况下，以精确和可控的方式引导大量激光能量进入物质的能力是至关重要的。了解负责精确雕刻激光物质相互作用的物理学是这个项目的主要推动力。当大量的激光与物质耦合时，能量会因物质破碎而耗散，释放出电子、离子和光子等次级粒子。分析碎裂过程的组成和成分之间的能量流动，提供了一个微观的基本物理视图。在这个项目中，使用灵敏的探测器配置来测量粒子的类型，它们的能量含量，以及它们的发射方向，同时考虑到干扰。该程序实现了利用半经典和量子模型预测的尺度来探索单个原子对强电磁场响应的全局物理的详细策略。关键的缩放参数是激光的颜色，即频率，该项目概述了新型波长激光如何将实验的广度扩展到一个未探索的领域，从而有助于我们对自然的整体理解。更具体地说，原子和分子暴露在强烈的（原子单位场），飞秒光脉冲，其波长可以从0.4-4 m变化。在这些低频率下，电子响应，例如电离，是高度非线性的，使电子振动的场能可以超过价电子的结合能。在实验中，电离电子在角度和能量上进行了分解，并研究了激光强度、极化和频率的函数关系。主要目标是绘制强场电离的全局行为，观察它如何随着尺度场参数的变化而演变，提供严格的理论测试，并确定物理中的不变行为。此外，该计划开发的激光源在科学和技术方面具有广泛的应用。本研究的跨学科性质与最先进的光学工程相结合，为本科生和研究生提供了极好的训练基地。前小组成员正在为学术界、能源和国防实验室以及私营部门的各个科学技术领域做出贡献。

The fundamental interaction of laser light with matter provides the foundation of modern basic and applied optical research. The impact on basic research was exemplified by the recent detection of gravitational waves emitted by colliding black holes, which confirmed Einstein's theory of gravity. At the heart of this achievement is an optical interferometer detector. In general, interferometers have exquisite sensitivity for detecting small disturbances, be they gravitational waves propagating through space or the minute motion of an electron in an atom as explored in this project. The interaction of light and matter is also being exploited in applications that provide more tangible benefits to society, such as non-invasive surgery and future sources of energy. In these cases, the ability to direct large amounts of laser energy into matter in a precise and controllable manner is paramount. Understanding the physics responsible for precisely sculpting the laser-matter interaction is a major thrust of this project. When a large amount of laser light is coupled into matter, the energy is dissipated by fragmenting the matter, releasing secondary particles such as electrons, ions, and photons. Analyzing the composition of the fragmentation process and the energy flow among the constituents provides a microscopic view of the elementary physics. In this project, sensitive detector configurations are used to allow the measurement of the type of particles, their energy content, and their emission direction, taking into account interference. This program implements a detailed strategy of utilizing the scaling predicted by semi-classical and quantum models for exploring the global physics of a single atom response to an intense electromagnetic field. The critical scaling parameter is the color, i.e. frequency, of the laser light and the project outlines how novel wavelength lasers can extend the breadth of experiments into an unexplored regime and thus contribute to our overall understanding of nature. More specifically, atoms and molecules are exposed to intense (atomic unit of field), femtosecond light pulses whose wavelength can be varied from 0.4-4 μm. At these low frequencies, the electronic response, e.g. ionization, is highly nonlinear and the field energy that quivers the electron can exceed the binding energy of the valence electron. In the experiment, the ionized electrons are resolved in angle and energy, and studied as a function of laser intensity, polarization and frequency. The main objectives are to map the global behavior of strong-field ionization, observe how it evolves with scaled field parameters, provide stringent tests of theory and identify the invariant behavior in the physics. In addition, the laser sources developed by this program have broad applications in science and technology. The interdisciplinary nature of this research coupled with state-of-the-art optical engineering provide an excellent training ground for both undergraduate and graduate students. Former group members are contributing to various areas of science and technology in academia, energy and defense laboratories, and the private sector.