Quantum Phenomena in Solids

非技术总结该奖项支持量子材料的理论研究和教育。从根本上说，地球上的一切都是由量子力学支配的。然而，尽管量子理论对于理解材料的总体性质至关重要，例如金属和绝缘体的存在，以及磁性现象，但它很少直接在更宏观的世界中显现出来。这个项目旨在通过研究在实验室规模的观测中量子效应异常明显的材料来弥合这一差距。这些量子材料提供了在更经典的物质中无法实现的新功能。这项研究主要集中在两个领域：量子磁学和传导电子的“液体”。在量子磁铁中，量子纠缠现象--一种奇怪的情况，即一个系统必须被认为同时处于多个经典态--可以从理论上设计，也可以通过实验来研究。这个项目将研究和量化“受挫”磁铁中的纠缠，在这种纠缠中，电子之间的竞争磁相互作用会产生奇异的量子力学效应。导电材料的研究集中在可以控制量子效应的新系统，以及可以通过电学测量直接探测这些效应的系统。具体地说，这包括由元素周期表第5行中出现的过渡金属元素制成的化合物，以及人工量子材料，一次生长一层原子。所有的研究都涉及理论技术的发展、数值计算和分析计算的结合，以及与实验研究的密切相互作用。研究生和本科生将以一种基本的方式参与研究，在分析推理、数学方法、计算和科学交流方面对他们进行广泛的培训，这些知识构成了STEM领域许多职业的基础，无论是在物理领域还是在物理领域。该奖项支持理论研究和教育，旨在解决理解和控制固体中的量子关联的问题，通过开发具有目前可用的有用功能的新材料和结构，并通过扩展基本科学框架来在新的制度和新的阶段理解物质。具体项目集中在高度量子磁性和相关的巡回材料上。这项研究将使用一系列不同的理论技术：唯象模型、统计力学、场论、从头计算模拟、密度矩阵重整化群和对称性分析。在量子磁学领域，目标是将奇异、非局域纠缠和量子临界态等前沿概念与实验对峙。这项研究将讨论量子自旋液体和受挫的铁磁体和亚铁磁体，解决主要的公开问题和量子有序的新范式。巡回关联系统的研究直接冲击了现代材料的前沿--5d过渡金属和氧化物异质结构。具体的项目确定了几个很有可能被发现的方向：在新的地点测试非传统超导和量子临界输运的想法的框架，以及澄清氧化物异质结构中定域电子和巡回电子的相互作用。所有的研究都充分融合了研究生和博士后，他们将接受物理学前沿领域以及科学过程和交流方面的培训。

NONTECHNICAL SUMMARY This award supports theoretical research and education on quantum materials. Fundamentally, everything on earth is governed by quantum mechanics. Yet, while quantum theory is essential to understanding the gross properties of materials, for example the existence of both metals and insulators, and the phenomena of magnetism, it rarely manifests itself directly in the more macroscopic world. This project aims to bridge this gap by investigating materials in which quantum effects are unusually apparent in laboratory-scale observations. These quantum materials offer new functionalities that could not be achieved in more classical substances. The research is broadly focused on two areas: quantum magnetism and conducting "liquids" of electrons. In quantum magnets, the phenomena of quantum entanglement - the strange situation in which a system must be considered to be in multiple classical states simultaneously - can be designed theoretically and investigated experimentally. This project will investigate and quantify entanglement in "frustrated" magnets, in which competing magnetic interactions between electrons induce exotic quantum mechanical effects. The research in conducting materials focuses on novel systems where quantum effects can be controlled, and where these effects may directly be probed by electrical measurements. Specifically this includes compounds made from transition metal elements that appear in the 5th row of the periodic table of the elements, and artificial quantum materials grown one layer of atoms at a time. All the research involves a combination of development of theoretical techniques, numerical and analytical calculations, and close interplay with experimental studies. Graduate and undergraduate students will be involved in an essential way in the research, training them broadly in analytical reasoning, mathematical methods, computation, and scientific communication, which form the basis for many careers in STEM fields, both in and out of physics.TECHNICAL SUMMARY This award supports theoretical research and education aimed to address the problem of understanding and controlling quantum correlations in solids, by developing new materials and structures with useful functionality not currently available, and by extending the basic scientific framework to understand matter in new regimes and new phases. Specific projects focus on highly quantum magnetism and correlated itinerant materials. The research will be carried out using a diverse set of theoretical techniques: phenomenological modeling, statistical mechanics, field theory, ab initio simulations, density matrix renormalization group, and symmetry analysis.In the area of quantum magnetism, the goal is to bring cutting-edge concepts of exotic, non-locally entangled and quantum critical states into confrontation with experiment. This research will address quantum spin liquids and frustrated ferromagnets and ferrimagnets, addressing major open questions and new paradigms for quantum ordering. Study of itinerant correlated systems directly attacks the frontiers of modern materials - 5d transition metals and oxide heterostructures. Specific projects identify several directions with a high likelihood for discovery: frameworks to test ideas of unconventional superconductivity and quantum critical transport in new venues, and clarifying the interplay of localized and itinerant electrons in oxide heterostructures. All the research fully integrates graduate students and postdocs, who will be trained in forefront areas of physics and in the scientific process and communication.