Engineering Phonons in Hybrid Nanostructures by Design and Understanding Their Roles in A Few Physical Processes

非技术摘要声子是固体中原子的集体振动，可以被认为是粒子在固体中运动。它们负责材料的许多性质，如导热系数和热膨胀。它们甚至在材料在量子计算等新应用中的性能方面发挥着作用。了解甚至利用这些粒子如何相互作用，对于设计和优化新材料是至关重要的。这个项目的重点是了解声子如何在几个选定的物理过程中相互作用。这项研究是通过使用从材料设计和胶体量子结构的合成到超快光学光谱学的多学科实验工具来完成的，因此它为学生的培训、K-12的推广和课程开发提供了肥沃的土壤。技术摘要本项目支持一项实验活动，目的是了解纳米尺度上的声子相互作用，并通过采用多管齐下的实验方法解决几个声子介导的基本过程。它特别将超快光学光谱与预先设计的胶体杂化纳米结构相结合，可以为声子工程提供定义良好的纳米级界面拓扑结构。这项研究直接涉及研究生解决几个基本问题所需的工具和技术方面的培训：界面对称性(中心对称和非中心对称界面)对纳米级声子特性的影响；界面耦合声子的所有光学控制及其在时间域中的相互作用；了解光激发声子和其他量子动力学之间的相互作用。该项目的完成将提高我们的纳米材料工程能力和理想声子性质的新设计指南，以及我们对声子依赖的物理过程的理解。这项工作非常重要，因为具有定义良好的声子工程界面拓扑的混合纳米结构可以用作功能声子器件的构建块。除了研究生和本科生的实验室培训外，该项目还允许建立综合教育平台，在课堂上开展前沿研究活动，并开展各种外联活动，特别侧重于少数族裔学生的教育。

Non-Technical AbstractPhonons are the collective vibrations of the atoms in a solid and can be thought of as particles moving though the solid. They are responsible for many properties such as the thermal conductivity and thermal expansion of materials. They even play a role in how materials will perform in new applications such as for quantum computing. Understanding, and even harnessing, how these particles interact with each other is essential for designing and optimizing new materials. This project focuses on understanding how phonons interact in a few select physical processes. This research is accomplished by employing multidisciplinary experimental tools, ranging from materials design and synthesis of colloidal quantum structures to ultrafast optical spectroscopy, and it thus provides a fertile ground for students' training, K-12 outreach and curriculum development. Technical AbstractThis project supports an experimental activity with a goal to understand phononic interactions at the nanoscale and to address a few phonon-mediated fundamental processes by adopting a multi-pronged experimental approach. It particularly combines ultrafast optical spectroscopy with pre-designed colloidal hybrid nanostructures that can possess well-defined nanoscale interface topology for phonon engineering. This research directly involves graduate students training in tools and techniques needed to address a few fundamental issues: effect of interfacial symmetry (centrosymmetric vs. non-centrosymmetric interfaces) on nanoscale phonon characteristics; all optical control of interfacially coupled phonons and their interplay in time domain; understanding interactions between optically excited phonons and other quantum dynamics. Accomplishment of this project should advance our nanoscale materials engineering capability and new design guidelines for desirable phonon properties, as well as our understanding of phonon-dependent physical processes. This work is additionally important because hybrid nanostructures with well-defined interface topology for phonon engineering can be utilized as building blocks for functional phononic devices. In addition to graduate and undergraduate students' laboratory training, this project also allows for integrated education platform with cutting-edge research activities in classroom and various outreach activities with particular focus on underrepresented minority students' education.