NSF/DMR-BSF: Theory of Quantum Materials

非技术总结该奖项支持在所谓的“量子材料”中相互作用的电子和离子的原子尺度模型的理论研究。量子材料的一些例子包括高温超导体，两层碳原子层彼此重叠，具有相对扭曲角，以及电子-电子相互作用能比它们的动能大得多的材料。这些系统通常具有许多科学上有趣和技术上重要的特性，这些特性是从其组成实体作为一个整体的复杂相互作用中集体出现的。虽然量子材料的特定性质敏感地依赖于它们的结构和量子化学，但某些新兴的性质，如高温超导性，可以从更一般的量子统计力学角度来理解。这种观点的优点是它的通用性，理想的承诺，它可以导致数学控制良好的解决方案的范式模型，可以作为一个框架的定性理解感兴趣的材料的属性。在这个项目中，主要研究人员将研究一系列这样的原子尺度模型，这些模型涉及当代凝聚态物理学的核心问题。量子材料理论的最新进展已经并将继续具有超越物理学的实际和概念意义。该项目涉及的问题是物理学广泛子领域的核心，包括凝聚态背景下量子材料的传统研究，弦理论和量子引力背景下强相互作用物质的研究，原子分子和光学物理背景下冷原子凝聚物的研究，以及探索和利用量子信息理论新思想的场所。更一般地说，量子材料在一系列更应用的科学中发挥着重要作用，因此，对该项目中要研究的问题的更多理解也有可能影响科学和技术的更广泛发展。参与这项研究的学生和博士后有可能成为该领域未来的领导者，而那些没有继续从事物理学研究的人也将发展技能，使他们能够在更广泛的背景下为社会做出贡献。技术概述该奖项支持量子材料中相互作用的电子和离子的原子尺度模型的理论研究。一个重点是微观机制，引起的各种对称性破缺的阶段，填充低温达到的相图，这些材料，特别是超导性和电荷密度波。该研究将集中在重要的非普遍的，但强大的，属性，确定基本的能量和温度标度的特点，这些阶段，包括过渡温度。感兴趣的另一个焦点是强相互作用系统在准粒子范式崩溃的温度和相互作用强度制度的输运性质。虽然费米液体范式的崩溃在各种实验上感兴趣的材料系统中是显而易见的，但很可能并非所有的非费米液体金属都是相同的。一个重要的目标是识别基本特征，这些特征允许这些状态更多地通过它们是什么而不是它们不是什么来识别，并通过识别表现出类似属性的可解模型问题来理解这些行为。最后，研究的一个重要组成部分将是对量子临界点附近系统的普遍性质的早期研究的延续和扩展，在量子临界点处，基态秩序的性质发生质的变化，例如金属系统中的量子临界现象。量子材料理论的最新进展已经并将继续具有超越物理学的实际和概念意义。该项目涉及的问题是物理学广泛子领域的核心，包括凝聚态背景下量子材料的传统研究，弦理论和量子引力背景下强相互作用物质的研究，原子分子和光学物理背景下冷原子凝聚物的研究，以及探索和利用量子信息理论新思想的场所。更一般地说，量子材料在一系列更应用的科学中发挥着重要作用，因此，对该项目中要研究的问题的更多理解也有可能影响科学和技术的更广泛发展。参与该研究的学生和博士后有可能成为该领域未来的领导者，而那些没有继续从事物理学研究的人也将发展技能，使他们能够在更广泛的背景下为社会做出贡献。该奖项反映了NSF的法定使命，并通过使用基金会的智力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 award supports theoretical research on atomic scale models of interacting electrons and ions in so-called "quantum materials". Some examples of quantum materials include high-temperature superconductors, two layers of carbon atom sheets on top of each other with a relative twist angle, and materials in which the electron-electron interaction energies are much larger compared to their kinetic energies. These systems typically have many scientifically interesting and technologically important properties that emerge collectively from the complex interactions of their constituent entities as a whole. While the specific properties of quantum materials depend sensitively on their structure and quantum chemistry, certain emergent properties, such as high-temperature superconductivity, can be understood from a more general quantum statistical mechanical perspective. The advantage of such a perspective is its generality, and ideally the promise that it could lead to mathematically well-controlled solutions to paradigmatic models that can serve as the framework for a qualitative understanding of the properties of interesting materials. In this project, the principle investigator will study an array of such atomic scale models on material systems and topics that are at the heart of contemporary condensed matter physics.Recent advances in the theory of quantum materials have had, and will continue to have, both practical and conceptual implications beyond physics. The issues involved in this project are central across a broad range of subfields of physics including the traditional study of quantum materials in a condensed matter context, studies of strongly interacting matter in a string theory and quantum gravity context, studies of cold atom condensates in atomic-molecular-and-optical physics context, and as a venue for exploring and exploiting new ideas in quantum information theory. More generally, quantum materials play an important role in a range of more applied sciences, and hence, increased understanding of the problems to be investigated in this project has the potential to influence broader developments in science and technology as well. Students and postdocs, who will be involved in this research, are likely to develop into future leaders of the field, while those who do not continue in physics will nonetheless develop skills which will allow them to make contributions to society in a broader context.TECHNICAL SUMMARYThis award supports theoretical research on atomic scale models of interacting electrons and ions in quantum materials on several fronts. One focus is on the microscopic mechanisms that give rise to the various broken symmetry phases that populate the low temperature reaches of the phase diagrams of such materials, especially superconductivity and charge density waves. The research will focus on the significant non-universal, but robust, properties that determine the basic energy and temperature scales which characterize these phases, including transition temperatures. Another focus of interest are transport properties of strongly interacting systems in regimes of temperature and interaction strengths in which the quasiparticle paradigm breaks down. While the breakdown of the Fermi liquid paradigm is apparent in a variety of experimentally interesting material systems, it is likely that not all non-Fermi-liquid metals are the same. An important goal is to identify basic features that allow such states to be identified more by what they are than by what they are not, and to make progress on understanding these behaviors by identifying solvable model problems that exhibit similar properties. Finally, an important component of the research will be a continuation and extension of earlier studies of the universal properties of systems near a quantum critical point at which the nature of the ground-state order changes qualitatively, such as in quantum critical phenomena in metallic systems. Recent advances in the theory of quantum materials have had, and will continue to have, both practical and conceptual implications beyond physics. The issues involved in this project are central across a broad range of subfields of physics including the traditional study of quantum materials in a condensed matter context, studies of strongly interacting matter in a string theory and quantum gravity context, studies of cold atom condensates in atomic-molecular-and-optical physics context, and as a venue for exploring and exploiting new ideas in quantum information theory. More generally, quantum materials play an important role in a range of more applied sciences, and hence, increased understanding of the problems to be investigated in this project has the potential to influence broader developments in science and technology as well. Students and postdocs, who will be involved in this research, are likely to develop into future leaders of the field, while those who do not continue in physics will nonetheless develop skills which will allow them to make contributions to society in a broader context.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.