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

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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.