CAREER: Theoretical and Numerical Investigation of Symmetric Mass Generation

职业：对称质量生成的理论和数值研究

• 批准号: 2238360
• 负责人: Yi-Zhuang You
• 金额: $ 57.5万
• 依托单位: University of California-San Diego
• 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: 2023-01-15 至 2027-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2238360&HistoricalAwards=false
• 关键词: CAREER; Theoretical; Numerical; Investigation; Symmetric

NONTECHNICAL SUMMARYThis CAREER award supports research and educational activities to explore novel quantum mechanisms that transform metals into insulators by increasing the interaction strength between electrons in such materials. In solid-state physics, the electronic structure theory provides the standard description for metals and insulators, such that the highest-energy electrons lie within an energy band for metals or in the band gap, a forbidden zone, as is the case for insulators. In this theory, transforming material from metal to insulator corresponds to a band gap opening in the electron energy spectrum, which always requires a change in the symmetry properties of the material to modify its band structure. This research aims to study a different mechanism for the metal-to-insulator transformation that is beyond the standard electronic structure theory in which the interaction and subsequent correlated motion of the electrons play the central role. The novel mechanism is called symmetric mass generation, which opens an excitation gap in the electron many-body energy spectrum without any change of symmetry properties — a phenomenon that is not explained by standard electronic structure theory. Understanding this novel mechanism may have implications in classifying quantum phases of matter in condensed matter physics and understanding the origin of mass for fundamental matter particles in high-energy physics. This project will investigate symmetric mass generation with an aim to address: (1) how appropriate interactions can be designed to realize this phenomenon, (2) what happens precisely as the metal becomes an insulator, (3) what are the unique experimental signatures of the novel insulator that distinguish it from conventional band insulators. The educational activity focuses on retaining LGBT+ (lesbian, gay, bisexual, transgender, and other gender and sexual minorities) students in physics by providing them with research opportunities and increasing LGBT+ visibility on campus. The effort will build a more diverse and inclusive academic environment that attracts talented under served students to physics and contribute to developing a diverse and globally competitive workforce in science.TECHNICAL SUMMARYThis CAREER award supports research and educational activities to study a novel mechanism for the gap opening (mass generation) of fermions in interacting quantum many-body systems, called the symmetric mass generation. The mechanism is a non-perturbative interaction-driven gap-opening effect that cannot be interpreted as a change in the single-particle band structure. Symmetric mass generation provides a new mechanism for metal-insulator transition beyond current band theory in condensed matter physics and a new origin for fermion mass beyond the standard Higgs mechanism. This research can advance the understanding of interacting topological insulators and transform the frontier knowledge about mass generation. The research will explore three related aspects: (1) the principle of designing appropriate interaction to realize the symmetric mass generation insulating phase, (2) the universal properties of the gap-opening transition under the symmetric mass generation interaction, and (3) the effect of doping symmetric mass generation insulators and the possibility to realize symmetric mass generation on the Fermi surface in a Fermi liquid. The research will combine field theory, for example, categorical symmetry, duality, monopole scaling, and dimension reduction, and numerical simulation, for example machine-learning-assisted variational Monte Carlo methods, to tackle scientific problems about symmetric mass generation. The research outcome will advance the knowledge frontier of interacting topological phases, strongly correlated materials, and lattice regularization for chiral fermions. The educational activities will focus on supporting and retaining LGBT+ (lesbian, gay, bisexual, transgender, and other gender and sexual minorities) undergraduates in physics and building a welcoming local community for LGBT+ students/researchers at all levels. These objectives will be attained by (1) providing mentored research opportunities to the targeted group and (2) initiating and organizing a weekly tea-time social event for LGBT+ students/researchers in Physics Department at UCSD.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.

非技术性总结该职业奖支持研究和教育活动，以探索通过增加此类材料中电子之间的相互作用强度将金属转化为绝缘体的新型量子机制。在固态物理学中，电子结构理论提供了金属和绝缘体的标准描述，这样最高能量的电子就位于金属的能带内或带隙中，这是一个禁区，就像绝缘体一样。在该理论中，将材料从金属转变为绝缘体对应于电子能谱中的带隙开口，这总是需要改变材料的对称性以修改其能带结构。本研究旨在研究金属到绝缘体转变的不同机制，该机制超出了标准电子结构理论，其中电子的相互作用和随后的相关运动起着核心作用。这种新的机制被称为对称质量产生，它在电子多体能谱中打开了一个激发间隙，而没有任何对称性的变化-这种现象无法用标准电子结构理论解释。理解这种新的机制可能会对凝聚态物理学中物质的量子相分类和理解高能物理学中基本物质粒子的质量起源产生影响。该项目将研究对称质量的产生，旨在解决：（1）如何设计适当的相互作用来实现这种现象，（2）当金属成为绝缘体时会发生什么，（3）新型绝缘体的独特实验特征是什么，将其与传统的带状绝缘体区分开来。教育活动的重点是保留LGBT+（女同性恋，男同性恋，双性恋，变性人，和其他性别和性少数）学生在物理通过为他们提供研究机会，并增加LGBT+在校园的知名度。这一努力将建立一个更加多样化和包容性的学术环境，吸引有才华的学生学习物理学，并为发展一个多样化和具有全球竞争力的科学人才队伍做出贡献。技术总结该职业奖支持研究和教育活动，研究相互作用的量子多体系统中费米子的差距开放（质量产生）的新机制，称为对称质量产生。该机制是一个非微扰相互作用驱动的间隙开放效应，不能解释为单粒子能带结构的变化。对称质量的产生为凝聚态物理中的金属-绝缘体跃迁提供了一种超越电流带理论的新机制，也为费米子质量提供了一种超越标准Higgs机制的新起源。这一研究可以促进对相互作用拓扑绝缘体的理解，并转化质量产生的前沿知识。本研究将探讨三个相关的方面：（1）设计适当的相互作用以实现对称质量产生绝缘相的原理;（2）对称质量产生相互作用下的隙-开跃迁的普适性质;（3）掺杂对称质量产生绝缘体的影响以及在费米液体中费米表面实现对称质量产生的可能性。该研究将结合联合收割机场论，例如分类对称性，对偶性，双尺度和降维，以及数值模拟，例如机器学习辅助变分蒙特卡罗方法，以解决有关对称质量生成的科学问题。研究成果将推进手征费米子的相互作用拓扑相、强关联材料和晶格正则化等前沿知识。教育活动将侧重于支持和保留LGBT+（女同性恋，男同性恋，双性恋，变性人和其他性别和性少数）物理本科生，并为LGBT+学生/各级研究人员建立一个欢迎的当地社区。这些目标将通过以下方式实现：（1）为目标群体提供指导性研究机会;（2）为UCSD物理系的LGBT+学生/研究人员发起和组织每周一次的茶会社交活动。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。

项目成果

Variational Monte Carlo study of symmetric mass generation in a bilayer honeycomb lattice model

• DOI: 10.1103/physrevb.108.125130
• 发表时间: 2022-12
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: W. Hou;Yi-Zhuang You