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

声子是固体中原子的集体振动，可以被认为是在固体中运动的粒子。 它们负责许多性质，例如材料的导热性和热膨胀。 它们甚至在材料如何在量子计算等新应用中发挥作用。 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至关重要。这个项目的重点是了解声子如何在一些选择的物理过程中相互作用。这项研究是通过采用多学科的实验工具，从材料设计和胶体量子结构的合成，以超快光学光谱完成的，因此它为学生的培训，K-12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个实验活动，其目标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来解决一些声子介导的基本过程。它特别结合了超快光学光谱与预先设计的胶体混合纳米结构，可以拥有明确的纳米级界面拓扑结构的声子工程。这项研究直接涉及研究生培训所需的工具和技术，以解决一些基本问题：界面对称性（中心对称与非中心对称界面）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域中的相互作用;理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新的设计准则，以获得理想的声子特性，以及我们对声子相关物理过程的理解。这项工作是非常重要的，因为混合纳米结构与明确定义的界面拓扑结构的声子工程可以被用作构建模块的功能声子器件。除了对研究生和本科生进行实验室培训外，该项目还提供了一个综合教育平台，在课堂上开展前沿研究活动，并开展各种外联活动，特别关注代表性不足的少数民族学生的教育。

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.