Towards a Unified Framework of Quantum Dynamics of Nonlinear Optical and Transport Processes

这个项目推进和拓宽了我们对强光下材料的基本科学认识。感兴趣的是物理定律与日常经验截然不同的现象和材料，因为材料内部的粒子很小，即量子物理学和量子材料。提高我们对辐照量子材料的认识将促进它们在未来量子技术中的应用，例如更高效的太阳能收集、更快的计算机和光电子应用。本研究开发了光学和量子凝聚态物理的新概念和新方法，使这两个知识领域受益。教育和推广工作包括开发一门新的计算物理课程，为高年级本科生（包括来自附近少数民族服务机构的学生）举办研讨会，为参加“向上发展”计划的低收入高中学生开发为期一天的STEM课程单元，通过美国国务院的国际教育领袖计划接待中学教师，并指导本科生和研究生进行研究。这些努力旨在扩大和多样化STEM劳动力。对清洁能源的需求引起了人们对太阳能收集的极大兴趣。非传统的光伏机制，如所谓的大块光伏效应，是太阳能收集和新型光电应用的有希望的候选者。然而，大块光伏效应的关键方面还没有得到很好的理解。本项目旨在建立一个理论框架来分类和统一晶体固体中的非线性输运，包括体光伏效应。感兴趣的材料包括二维铁电体和拓扑材料。该框架将确定耗散和载流子相互作用的作用，这些作用在现有的分析或数值理论中尚未解决，但对于理解实验和发现新的非线性现象非常重要。本项目采用解析场理论方法和数值密度泛函方法。在一个相关的主题中，光也正在成为工程材料特性的通用工具，例如最近实现的弗洛克-布洛赫状态和光诱导的异常霍尔效应。这些状态非常短暂，因为受辐照的物质很快就会升温。理解热化的途径对于实现新的非平衡态的应用是至关重要的。PI将构建包括电子相互作用，激子和声子在内的多体热化模型，并在此过程中评估现实场景中激光驱动非平衡态的机遇和挑战。理论模型将通过与开展实验研究的伙伴的密切合作得到实验验证。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。

Nontechnical summaryThis project advances and broadens our basic scientific understanding of materials under intense illumination. Of interest are phenomena and materials where the laws of physics are radically distinct from day-to-day experience due to the smallness of particles inside materials, i.e., quantum physics and quantum materials. Advancing our knowledge of irradiated quantum materials will facilitate their use in future quantum technologies, e.g., more efficient solar energy harvesting, faster computers and optoelectronic applications. This research develops new concepts and methods in both optics and quantum condensed matter physics, benefiting both fields of knowledge. Education and outreach efforts include developing a new computational physics course, hosting a workshop for senior undergraduate students (including those from nearby minority-serving institutions), developing a one-day STEM curriculum unit for low-income high school students enrolled in Upward Bound, hosting middle school teachers via the US State Department’s International Leaders in Education Program, and mentoring undergraduates and graduate students in research. These efforts aim to expand and diversify the STEM workforce.Technical summaryThe need for clean energy sources has led to great interest in solar energy harvesting. Unconventional photovoltaic mechanisms such as the so-called bulk photovoltaic effect are promising candidates for both solar energy harvesting and novel optoelectronic applications. Key aspects of the bulk photovoltaic effect, however, are not well understood. This project aims to develop a theoretical framework to classify and unify nonlinear transport in crystalline solids including the bulk photovoltaic effect. Materials of interest include two-dimensional ferroelectrics and topological materials. The framework will ascertain the role of dissipation and carrier interactions not yet addressed in existing analytical or numerical theories but which are important to understand experiments and uncover novel nonlinear phenomena. The project uses analytical field theoretic methods and numerical density functional approaches.In a related topic, light is also emerging as a versatile tool for engineering the properties of materials as exemplified by the recent realization of the Floquet-Bloch state and the light-induced anomalous Hall effect. These states are very short-lived because irradiated materials quickly heat up. Understanding pathways to thermalization is of fundamental importance in realizing applications of novel nonequilibrium states. The PI will construct models of many-body thermalization which include electron interactions, excitons and phonons and in so doing assess the opportunities and challenges of laser-driven nonequilibrium states in realistic scenarios. Theoretical models will be experimentally validated via close collaboration with partners conducting experimental research.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.