Quantum Phenomena in Solids

固体中的量子现象

• 批准号: 1506119
• 负责人: Leon Balents
• 金额: $ 35.4万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506119&HistoricalAwards=false
• 关键词: Quantum; Phenomena; Solids

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.

该奖项支持量子材料的理论研究和教育。从根本上说，地球上的一切都受量子力学的支配。 然而，虽然量子理论对于理解材料的总体性质是必不可少的，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表现出来。 该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：量子磁性和电子的导电“液体”。 在量子磁体中，量子纠缠现象--一个系统必须被认为同时处于多个经典状态的奇怪情况--可以在理论上设计和实验上研究。 该项目将研究和量化“受挫”磁体中的纠缠，其中电子之间的竞争磁相互作用引起奇异的量子力学效应。 导电材料的研究重点是量子效应可以控制的新系统，这些效应可以直接通过电学测量来探测。 具体来说，这包括由元素周期表第五行中出现的过渡金属元素制成的化合物，以及一次生长一层原子的人工量子材料。 所有的研究都涉及理论技术的发展，数值和分析计算的结合，并与实验研究密切相关。 研究生和本科生将以重要的方式参与研究，对他们进行分析推理、数学方法、计算和科学交流方面的广泛培训，这些构成了物理学内外STEM领域许多职业的基础。技术总结该奖项支持旨在解决理解和控制固体中量子相关性问题的理论研究和教育，通过开发具有目前尚不具备的有用功能的新材料和结构，并通过扩展基本科学框架来理解新制度和新阶段的物质。具体项目集中在高度量子磁性和相关的巡回材料。 研究将使用各种理论技术进行：唯象建模、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的前沿概念与实验进行对抗。 这项研究将解决量子自旋液体和受挫的铁磁体和亚铁磁体，解决主要的开放问题和量子有序的新范式。 巡游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。 具体项目确定了几个发现可能性很高的方向：在新场所测试非常规超导性和量子临界输运思想的框架，以及澄清氧化物异质结构中局部和巡回电子的相互作用。 所有的研究都充分整合了研究生和博士后，他们将在物理学的前沿领域以及科学过程和沟通方面接受培训。