CAREER: Theories of Gapless Quantum Matter Beyond Quasiparticles

职业：超越准粒子的无带隙量子物质理论

• 批准号: 2237522
• 负责人: Debanjan Chowdhury
• 金额: $ 60.77万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-01 至 2028-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2237522&HistoricalAwards=false
• 关键词: CAREER; Theories; Gapless; Quantum; Matter

NONTECHNICAL SUMMARYThis CAREER award supports an integrated research, outreach, and education program in theoretical condensed matter physics. At sufficiently low temperature some materials can exhibit superconductivity, a state of matter where electrons self-organize into a cooperative state which can conduct electricity without dissipation. The search for superconductivity at high temperatures is driven by the potential of superconductors to transform the future of quantum technologies and human society, with applications in energy storage and transmission, medical diagnostics, and quantum computing. However, the microscopic reasons for superconductivity at high temperature remain mysterious. The research will be focused on a class of unconventional metals, which are the “parent” states for high temperature superconductors. Unlike simple metals such as copper, whose properties can be effectively understood by considering the electrons one at a time, these unconventional metals are best described as a collective quantum fluid where the electrons are strongly entangled over long distances with one another. This research will develop the required technical framework to describe these entangled electronic liquids. This will pave the way for identifying the key microscopic mechanisms responsible for the origin of superconductivity at high temperatures.The PI and his group will develop new theoretical methods building on recent theoretical developments across different subfields. The PI will develop exact theoretical methods that have a predictive power that can be tested against experiments on real materials in the laboratory. The resulting outcome will impact the fundamental understanding of the collective quantum mechanical properties of trillions of entangled electrons, and potentially help guide the future search for new materials displaying exotic properties. The methods and results will be disseminated to the wider community.In parallel, the PI will initiate and participate in a variety of educational and outreach activities. Although quantum physics has impact on the development of new technologies that become part of everyone’s daily lives, it has a reputation for being inaccessible. The PI will start a new podcast series, which will host informal discussions with a diverse lineup of well-known researchers, to get students and the general public excited about the physics of quantum materials. The PI will also organize workshops for high school science teachers to co-develop engaging lesson plans. The PI will mentor undergraduate and graduate students in original research, and write pedagogical articles aimed at training them in the new scientific developments aligned with the research activities.TECHNICAL SUMMARYThis CAREER award supports an integrated research, outreach, and education program in theoretical condensed matter physics. The goal of the research will be to address some of the key facets of the long-standing mystery of high-temperature superconductivity. Specifically, the focus will be on the unusual gapless metallic phases out of which superconductivity emerges in quantum materials. Experiments suggest that the quantum motion of electrons is frustrated and entangled over long distances in strongly correlated metals, and the microscopic degrees of freedom, namely electrons and phonons, are strongly intertwined with each other. This research activity will develop novel, non-perturbative theoretical approaches to solve the problem of electronic liquids entangled with other collective degrees of freedom, to expose universal aspects of gapless quantum many-body systems.The PI will formulate new approaches for studying interacting gapless phases that do not rely on the existence of well-defined, electron-like (“quasiparticle”) excitations. To address their non-trivial dynamics, the PI will develop novel theoretical techniques that are based on technical advances in the study of frustrated magnets, thermalization in chaotic quantum many-body systems, and numerically exact algorithms that do not suffer from the fermion “sign problem”. The PI will build on the following conjectures: (i) interacting frustrated liquids offer a non-trivial starting point for including the effects of quantum fluctuations and describing previously unexplored gapless phases; and (ii) the conventional theory for electrical transport in metals can break down over a wide range of intermediate temperatures for sufficiently “chaotic” models with generic interactions. The PI will also exploit recent breakthroughs in the highly controllable moiré systems, focusing on the problem of narrow electronic bands coupled to low-energy phonons using numerically exact methods. Analyzing these questions will offer an important conceptual framework for tying together a vast amount of existing experimental data on high-temperature superconductors, and help direct the search for new materials displaying similar phenomena.The PI’s educational and outreach activities are integrated synergistically with the research. The PI will start a new podcast series with a diverse lineup of well-known researchers to increase awareness about the excitement in the field amongst the general public and students. The PI will mentor undergraduate and graduate students in original research, and write pedagogical articles aimed at training them at the new scientific developments aligned with the research activities. Leveraging existing infrastructure available at Cornell University through the STEM teacher program, the PI will organize a series of workshops for high school science teachers to co-develop engaging lesson plans.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.

非技术性总结这个职业奖项支持理论凝聚态物理的综合研究、推广和教育计划。在足够低的温度下，一些材料可以表现出超导电性，这是一种电子自组织成协作状态的物质状态，可以在不耗散的情况下导电。超导体有望改变量子技术和人类社会的未来，在能源储存和传输、医疗诊断和量子计算方面的应用，推动了对高温超导电性的探索。然而，高温超导的微观原因仍然是个谜。这项研究将集中在一类非传统金属上，这类金属是高温超导体的母体状态。与铜等简单金属不同，通过逐个考虑电子可以有效地了解其性质，这些非常规金属最好被描述为一种集体量子流体，其中电子在很长一段时间内相互强烈纠缠。这项研究将开发所需的技术框架来描述这些纠缠的电子液体。这将为确定高温超导起源的关键微观机制铺平道路。Pi和他的团队将在不同子领域的最新理论发展的基础上开发新的理论方法。PI将开发出精确的理论方法，这些方法具有预测能力，可以在实验室的真实材料实验中进行测试。由此产生的结果将影响对数万亿个纠缠电子的集体量子力学性质的基本理解，并可能有助于指导未来寻找具有奇异性质的新材料。有关的方法和成果将会向社会广泛宣传，同时，警队亦会发起和参与各项教育和外展活动。尽管量子物理对新技术的发展产生了影响，这些新技术已经成为每个人日常生活的一部分，但它有一个难以接触的名声。PI将开始一个新的播客系列，将主持与不同阵容的知名研究人员的非正式讨论，以让学生和普通公众对量子材料的物理感到兴奋。PI还将为高中科学教师组织研讨会，共同制定引人入胜的教案。PI将指导本科生和研究生进行原创研究，并撰写教学文章，旨在培训他们与研究活动相适应的新科学发展。技术总结这个职业奖项支持理论凝聚态物理的综合研究、推广和教育计划。这项研究的目标将是解决高温超导长期存在的谜团的一些关键方面。具体地说，重点将放在量子材料中出现超导的不寻常的无间隙金属相上。实验表明，在强关联金属中，电子的量子运动在很长的距离内受到阻碍和纠缠，微观自由度，即电子和声子，相互强烈地缠绕在一起。这一研究活动将发展新的、非微扰的理论方法来解决电子液体与其他集体自由度纠缠的问题，揭示无间隙量子多体系统的普遍方面。PI将制定新的方法来研究相互作用的无间隙相，而不依赖于明确定义的类电子(“准粒子”)激发的存在。为了解决他们的非平凡动力学问题，PI将开发新的理论技术，这些技术基于受挫磁体的研究、混沌量子多体系统中的热化以及不受费米子“符号问题”困扰的数值精确算法的技术进步。PI将建立在以下猜想的基础上：(I)相互作用的受挫液体为包括量子涨落的影响和描述以前未被探索的无缝隙相提供了一个不平凡的起点；以及(Ii)对于具有一般相互作用的足够“混乱”的模型，金属中电传输的传统理论可以在很大的中间温度范围内崩溃。PI还将利用高度可控的莫尔系统的最新突破，重点研究窄电子带与低能声子的耦合问题，使用精确的数值方法。分析这些问题将提供一个重要的概念框架，将现有的大量高温超导体实验数据联系在一起，并有助于指导寻找具有类似现象的新材料。PI的教育和推广活动与研究相结合。PI将开始一个新的播客系列，由不同的知名研究人员组成阵容，以提高公众和学生对这一领域的兴奋的认识。PI将指导本科生和研究生进行原创研究，并撰写教学文章，旨在培训他们了解与研究活动相一致的新科学发展。通过STEM教师计划，PI将利用康奈尔大学现有的基础设施，为高中科学教师组织一系列研讨会，共同制定引人入胜的教学计划。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

T-linear resistivity from magneto-elastic scattering: Application to PdCrO 2

磁弹性散射的 T 线性电阻率：在 PdCrO 2 中的应用

• DOI: 10.1073/pnas.2305609120
• 发表时间: 2023
• 期刊: Proceedings of the National Academy of Sciences
• 作者: Mendez-Valderrama, J. F.;Tulipman, Evyatar;Zhakina, Elina;Mackenzie, Andrew P.;Berg, Erez;Chowdhury, Debanjan
• 通讯作者: Chowdhury, Debanjan