Photoemission By Large Electron Wave Packets Emitted Out The Side of A Relativistic Laser Focus

本文从理论和实验两方面研究了自由电子对激光的散射。在实验中，电子波包将通过在强激光场中电离而产生，并且将观察到来自与激光束成直角的焦点的辐射。来自一个或几个电子的辐射光非常微弱，实验需要量子光学测量技术和高强度激光技术的不寻常组合。为了将这种低水平信号从显著的背景中分离出来，研究人员在时间（仅在纳秒宽的窗口中查看信号），空间（使用挡板和光纤耦合系统仅收集来自焦点空间位置的光子）和波长（使用带通滤波器仅查看相对论性红移信号，同时在压缩系统中明确屏蔽这些频率）中进行过滤。研究人员还将研究自由电子光电发射的理论基础，以及量子场描述如何与半经典框架适当相关。初步的工作已经完成了简化的情况下，驱动激光和发射的辐射被视为平面波场。扩展这种分析来描述局部相互作用并不容易，但有必要创建一个理论框架来理解该系统中的辐射。更广泛的影响包括在电子的粒子/波性质与光的粒子/波性质之间的界面背景下研究量子力学的基础，并寻求解决激光相互作用社区中不同研究人员持有的相互冲突的观点。这项工作将导致更好地理解光子的性质，特别是发射和吸收光子与量子测量过程（涉及波函数坍缩）之间的联系。该项目为本科生和研究生提供了机会，使他们在获得宝贵经验的同时，对工作做出有意义的贡献。

The work is a study of the scattering of laser light by free electrons both theoretically and experimentally. In the experiment, electron wave packets will be created through ionization in a strong laser field and radiation from the focus at right angles to the laser beam will be observed. The radiated light from one or a few electrons is extremely weak and the experiment requires the unusual combination of quantum-optics measurement techniques and high-intensity laser technology. To separate this low-level signal from the significant background, the investigators filter in time (looking only at the signal in a nanosecond wide window), space (using baffling and a fiber coupling system to collect only photons originating from the spatial location of the focus), and wavelength (using bandpass filters to view only the relativistic red-shifted signal while explicitly masking these frequencies in the compression system). The investigators will also study the theoretical underpinnings of free-electron photoemission and how the quantum-field description might be appropriately related to a semiclassical framework. Initial work has already been accomplished in the simplified case where the driving laser and the emitted radiation are treated as plane wave fields. Extending this analysis to describe localized interactions is non-trivial, but it is necessary to create a theoretical framework for understanding radiation in this system. The broader impacts include the study of the foundations of quantum mechanics in the context of the interface between the particle/wave nature of electrons and the particle/wave nature of light and seeks to resolve conflicting viewpoints held by different researchers in the laser-interaction community. This work will lead to a better understanding of the nature of photons, especially the connection between emitting and absorbing photons and the quantum measurement process (involving wave function collapse). The project provides opportunities for both undergraduate and graduate students to make meaningful contributions to the work while gaining valuable experience.