DMREF: Collaborative Research: The Search for Novel Superconductors in Moire Flat Bands

非技术描述：该项目将研究基于原子薄材料之间以扭曲角度堆叠的新型非常规超导体。当两个具有相似原子结构的原子层相互接触时，形成一个更大尺度的准周期结构，称为云纹图案。这些界面结构的电子结构可以通过调整扭转角度来设计。当电子能量分布较窄时，它们之间出现强的相关性，从而驱动系统成为无耗散超导态。实验和理论研究，结合先进计算方法的预测能力，将得到发展，以更好地理解工作中的物理机制，并将有助于设计具有更高转变温度的超导材料。该项目将提供对材料特性和现象的基本理解，这些特性和现象将支持超导电子器件在低能电子、量子传感以及更重要的量子计算应用中的应用。将培养新一代的科学家，他们将深入参与实验和理论/模型研究，并具有互补的专业知识。技术描述：二维范德华（vdW）材料的云纹异质结构工程导致量子异质结构。利用最近展示的扭曲vdW异质外延，研究人员将构建vdW同质/异质结构，以实现在云纹平带中出现的相关电子态。根据多尺度电子结构的理论和数学模型，该项目将实验研究具有不同寻常特性的多层二维超导系统，如栅极可调转变温度和非常规配对对称性。将探索各种材料平台，包括扭曲双双层石墨烯，扭曲三层石墨烯以及基于过渡金属二硫族化合物的扭曲同质和异质结构。理论指导将是本研究不可缺少的一部分，因为材料平台和扭转角度的选择是多种多样的，没有针对性的建模指导，仅靠实验是无法涵盖的。非常规的超导性也可以导致拓扑超导体的发展和发现，这可以用于量子计算。由于底层量子态的拓扑特性，在拓扑超导系统中实现的量子比特有望实现容错量子计算。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。

Non-technical Description: This project will investigate novel unconventional superconductors based on atomically thin materials stacked with a twisted angle between them. When two atomic layers with similar atomic structure meet each other, a larger scale quasi periodic structure called a moire pattern forms. Electronic structure of these interfacial structure can be engineered by adjusting the twisting angle. When the electron energy distribution is narrow, strong correlation between them appear, which can in turn drive the system to be a dissipationless superconducting state. Experimental and theoretical research, in conjunction with the predictive powers of advanced computational methods, will be developed to achieve a better understanding of the physical mechanisms at work and will contribute to the ability to design superconducting materials with higher transition temperatures. The project will provide fundamental understanding of the materials properties and phenomena that underpin superconducting electronic device applications in low energy electronics, quantum sensing, and more importantly quantum computing applications. A new generation of scientists will be trained who are deeply involved in both experimental and theoretical/modeling research with complimentary expertise.Technical Description: The moire heterostructure engineering of 2-dimensional (2D) van der Waals (vdW) materials leads to quantum heterostructures. Utilizing recently demonstrated twisted vdW heteroepitaxy, the investigators will construct vdW homo/hetero structures to realize correlated electronic states that appear in the moire flat bands. With inputs from theory and mathematical modeling of multiscale electronic structure, the project will experimentally investigate multilayer 2D superconducting systems with unusual properties, such as gate tunable transition temperature and non-conventional pairing symmetries. Various material platforms will be explored including twisted double bilayer graphene, twisted trilayer graphene and twisted homo- and hetetro-structures based on transition metal dichalcogenides. Theoretical guidance will be an indispensable part of this study since there are a variety of choices for material platforms and twist angle which cannot be covered by experiment alone without targeted modeling guide. Unconventional superconductivity can also lead into the development and discovery of topological superconductors, which can be utilized for quantum computing. The qubits realized in topological superconducting systems hold promise for fault-tolerant quantum computation, thanks to the topological nature of the underlying quantum states.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.