Optical properties of the superconducting hydrides and of topological materials

发现在室温下超导的材料仍然是凝聚态物理学的一个非常理想的目标。 它将彻底改变MRI成像仪在医院的使用，电力传输的电网和高速旅行的磁悬浮。 最近发现的超导临界温度Tc = 200 K的H3 S在150 GPa的压力下，随后的光学证据表明，驱动机制是电子-声子相互作用代表了一个量子飞跃。 系统研究其他材料和相关材料，有些在环境压力下是这一研究领域的核心。 我们建议提供理论支持，以指导实验学家在这方面的搜索和解释他们的结果，特别是因为它涉及到机制，以及如何可以操纵，以实现更高的Tc值。 光学已被证明是一个强大的技术在这方面的努力，我们是世界专家。 凝聚态物理学最近的第二个重要发展是拓扑材料的发现，它引入了新的概念，甚至是思考半金属的新方法。 它导致了我们对拓扑结构在提供全新功能的电子系统中的重要性的理解的快速发展。 这有可能对光电设备、自旋电子学、磁存储器、太阳能电池、水过滤、量子计算以及更广泛的通信产生变革性影响。 这一领域的新材料被迅速发现，部分原因是理论的进步。 强大的新数值技术使我们能够准确地预测电子结构和隐含的属性。 我们建议计算新的拓扑半金属，包括外尔和狄拉克材料，因为它们是在实验室中发现的选择属性，目的是增加了解什么新的和独特的性能是可能的。 已经在固态系统中发现了新的外尔费米子，而在高能粒子物理学中没有对应物。 因此，基础新物理学正在被发现，这可能会影响未来的技术。 拟议的研究计划还将为研究生提供先进的数学，数值和计算技术方面的扎实培训，以及许多其他领域的高度可取和可转移的技能。

The discovery of materials that superconduct at room temperature remains a highly desirable goal of condensed matter physics. It would revolutionize the use of MRI imagers in hospitals, the electrical grid for power transmission and magnetic levitation for high speed travel. The recent discovery of superconductivity with a critical temperature Tc = 200 K in H3S under 150 GPa pressure, and subsequent optical evidence that the driving mechanism is the electron-phonon interaction represents a quantum leap forward. The systematic study of other hydrides and related materials, some at ambient pressure is central to this area of research. We proposed to provide theoretical support to guide experimentalists in this search and to interpret their results particularly as it relates to mechanism and how it might be manipulated to achieve even higher values of Tc. Optics has been shown to be a powerful technique in this effort and we are world experts. A second important recent development in condensed matter physics has been the discovery of topological materials which has introduced new concepts and indeed new ways of thinking about semimetals. It has led to the rapid development of our understanding of the importance of topology in providing electronic systems with entirely new functionalities. This holds the potential for transformative impact on opto-electronic devices, on spintronics, magnetic memories, solar cells, water filtration, on quantum computing and more generally on communications. New materials in this area are discovered at a rapid rate partly because of advances in theory. Powerful new numerical techniques allows us to accurately predict electronic structure and implied properties. We propose to calculate select properties of new topological semimetals including Weyl and Dirac materials as they are discovered in the laboratory, with the aim of increasing understanding of what new and unique properties are possible. Already new Weyl fermions have been found in solid state systems that have no counterpart in high energy particle physics. So fundamental new physics is being discovered which could impact future technologies. The proposed research program will also provide solid training in advanced mathematical, numerical and computing techniques to graduate students, highly desirable and transferable skills to many other areas.