First-Principles Design of Charged Defects for Two-dimensional Quantum Technologies

该奖项支持研究和教育发展计算方法，旨在研究缺陷的性质，固体材料中的一种缺陷。PI将专注于极薄材料的缺陷，薄到被称为二维材料，以及由它们堆叠而成的分层材料。基于先进理论的计算方法可以用来帮助设计这些材料中的缺陷，以便它们可以用来发射单量子光或光子。这些单光子发射器可以成为新一代信息技术设备构建模块的核心。二维材料比传统的块状材料更有优势，例如，更容易生产和集成到固态设备中。在先进的传感、计算、信息、建模和通信技术中，计算方法在设计具有缺陷的二维材料中起着关键作用。这个项目与美国国家科学基金会的量子飞跃大想法是一致的。该项目包括旨在增加妇女在科学、技术、工程和数学（STEM）学科，特别是在物理科学领域的参与和代表性的教育活动。该项目旨在填补加州大学圣克鲁斯分校物理和材料化学教育课程的重大空白，并在材料科学与工程计划的保护下，在校园内建立理论/计算材料研究。这些活动包括为高年级本科生和研究生开发新的计算材料课程，通过各种现有项目为本科生提供研究机会，以及组织讲习班和研讨会，提供职业规划建议，特别是为女学生提供建议。该奖项支持理论和计算研究，以开发计算方法，并研究具有潜在应用于量子信息技术的材料。二维（2D）材料中的缺陷，如超薄六方氮化硼，在室温下具有偏振和超亮的单光子发射。这一发现为纳米光子学和量子信息的新兴应用开辟了新的可能性，具有比长期研究的金刚石中的氮空位中心（NV-）更好的可扩展性。尽管迄今为止已经通过实验证明了这些有希望的特性，但精确的二维材料缺陷特性第一性原理预测仍然具有挑战性。困难的出现主要是因为二维材料中的高各向异性介质屏蔽和强多体相互作用的存在，包括电子-空穴，电子-声子和缺陷-激子相互作用，这些都不包括在标准密度泛函理论计算机代码中。该团队计划开发高效的计算方法，以准确确定超薄二维材料和异质结中缺陷的缺陷电荷跃迁能级和激发态寿命，然后利用它们设计具有理想性质的复杂缺陷，用于量子发射体和基于第一性原理计算的量子计算应用。该研究有助于解决从第一性原理模拟二维材料中带电缺陷的长期问题，这需要适当处理二维平面附近电荷的静电势和多体摄动理论中屏蔽的库仑相互作用。通过该项目开发的精确电子结构方法可用于确定缺陷二维单层和异质结中的缺陷电荷跃迁水平，辐射激子重组寿命和声子辅助非辐射寿命。它们还将使二维材料中量子缺陷的合理设计成为可能。该项目包括旨在提高女性在STEM学科，特别是物理科学领域的参与度和代表性的教育活动。该项目的努力将填补加州大学圣克鲁斯分校（UCSC）物理和材料化学教育课程的重大空白，并在校园内建立理论和计算材料研究。来自物理系、化学系和工程系的学生可以参加研究，并在PI的小组中获得计算材料研究的第一手经验。该项目旨在招募女性和少数民族学生参与这些体验。该项目还将加强加州大学圣地亚哥分校的研究基础设施，这是一所西班牙裔服务机构。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识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 research and education to develop computational methodologies aimed to investigate properties of defects, a kind of imperfection in solid materials. The PI will focus on defects in extremely thin materials, so thin that they are called 2D materials, and layered materials made from stacking them. Computational methods based on advanced theories can be used to help design defects in these materials so that they can be used to emit a single-quantum of light or photon. These single photon emitters can be the heart of building blocks for a new generation of information technology devices. Two-dimensional materials have major advantages over more traditional bulk materials, allowing, for example, easier production and integration into solid-state devices. Computational methods play a key role in designing 2D materials with defects for advanced sensing, computing, information, modeling and communications technologies. This project is aligned with NSF's Quantum Leap Big Idea.This project includes educational activities aimed to increase participation and representation of women in science, technology, engineering, and math (STEM) disciplines, especially in the physical sciences. Efforts in this project are planned to fill a significant gap in the physical and materials chemistry educational curriculum at University of California, Santa Cruz and build up theoretical/computational materials research on the campus under the umbrella of the Materials Science & Engineering Initiative. The activities include developing new computational materials courses for upper-division undergraduate and graduate students, providing undergraduate research opportunities through various existing programs and organizing workshops and seminars that offer career planning advices, especially for women students.TECHNICAL SUMMARYThis award supports theoretical and computational research to develop computational methods and to investigate materials with potential application to quantum information technology. Defects in two-dimensional (2D) materials, such as ultrathin hexagonal Boron Nitride, have been found to be promising single-photon emitters with polarized and ultrabright single-photon emission at room temperature. This discovery opens new possibilities for emerging applications in nanophotonics and quantum information, with potentially much better scalability than the long-studied nitrogen vacancy center (NV-) in diamond. Despite the promising properties that have been experimentally demonstrated to date, accurate first-principles prediction of defect properties in 2D materials remains challenging. Difficulties arise mainly because of the highly anisotropic dielectric screening in 2D materials and the presence of strong many-body interactions, including electron-hole, electron-phonon, and defect-exciton interactions, which are not included in standard density functional theory computer codes. The plans to develop efficient computational methods to accurately determine defect charge transition levels and excited state lifetimes of defects in ultrathin 2D materials and heterojunctions, and then to use them to design complex defects with ideal properties for quantum emitters and quantum computation applications based on first-principles calculations.This research can contribute to resolving long-standing issues of simulating charged defects in 2D materials from first-principles, which necessitates proper treatment of electrostatic potentials of charges near a 2D plane and of the screened Coulomb interaction in many-body perturbation theory. Accurate electronic structure methods developed through this project can be used for determining defect charge transition levels, radiative exciton recombination lifetimes, and phonon-assisted non-radiative lifetimes in defective 2D monolayer and heterojunctions. They will also enable the rational design of quantum defects in 2D materials.This project includes educational activities aimed to increase participation and representation of women in STEM disciplines, especially in the physical sciences. Efforts in this project will fill a significant gap in the physical and materials chemistry educational curriculum at University of California, Santa Cruz (UCSC) and build up theoretical and computational materials research on the campus. Students from physics, chemistry, and engineering departments can join in the research and gain first-hand experience in computational materials research in the PI's group. The PI aims to recruit women and minority students to participate in these experiences. This project will also strengthen the research infrastructure at UCSC, a Hispanic Serving Institution.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.