Electron-electron interactions and topology in semiconductor and graphene quantum dots

半导体和石墨烯量子点中的电子-电子相互作用和拓扑

• 批准号: RGPIN-2014-03712
• 负责人: Hawrylak, Pawel
• 金额: $ 2.62万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=566049
• 关键词: Electron; electron; interactions; topology; semiconductor

Electron-electron interactions and topology are fundamental to the understanding of quantum materials and devices yet neither one is fully understood at present. Recent advances in nanotechnology make it possible to build artificial quantum materials, nanostructures and devices from single atoms, electrons, and spins. Our broadly defined research program aims at designing quantum systems both at the single particle and, most importantly, at the many-particle level. Such artificial tuneable structures will allow for the fundamental understanding of effects of electron-electron interactions and topology and pave the way toward their exploitation in quantum solid state devices addressing important technological challenges in information processing, sensing, security and energy harvesting. Four main research directions will be pursued. (i) theory of quantum dot networks in a field effect transistor described by fully tuneable, extended Hubbard model will be used to determine whether electron-electron interactions may lead to strongly correlated topological phases and allow for voltage control of spin needed in small quantum simulators, precursors of solid state quantum computers. (ii) atomistic theory of interacting electrons and holes in semiconductor quantum dots embedded in nanowires will be developed to determine the potential of these structures for single and entangled photon sources, photon-to-spin conversion and formation of a robust macroscopic quantum state due to e-e interactions in a modulation doped nanowire. (iii) theory of electronic and optical properties of quantum dots made of inverted band semiconductors, such as HgTe will be developed and conditions necessary for appearance of topologically protected spin-resolved surface states determined. The role of e-e interactions in the electronic, optical and transport properties of topological quantum dots will be determined as well as their application as strain, charge and spin sensors. (iv) the effects of electron-electron interactions, weak spin orbit coupling and hence absence of topological effects and lack of magnetism in graphene remain a challenge. By controlling lateral size of graphene one can open an energy gap and turn graphene, a semimetal, into a one atomic layer thick “semiconductor” quantum dot, breaking sublattice symmetry generates a magnetic moment and twisting into Mobius strip introduces topology. We will develop theoretical and computational tools enabling prediction of the electronic, optical, magnetic and topological properties of graphene quantum dots. This will allow the determination of optical properties of colloidal quantum dots for solar cells, electronic properties of quantum dot networks based on electron spin in bi-layer graphene and design of integrated graphene quantum dot based electronic circuits. This research program will advance progress in advanced quantum materials, nanostructures and devices for quantum and low power information processing, sensing and energy harvesting.

电子-电子相互作用和拓扑是理解量子材料和器件的基础，但目前还没有完全理解。纳米技术的最新进展使得利用单个原子、电子和自旋构建人工量子材料、纳米结构和器件成为可能。我们广泛定义的研究计划旨在设计单粒子和最重要的多粒子水平的量子系统。这种人工可调谐结构将允许对电子-电子相互作用和拓扑效应的基本理解，并为其在量子固态器件中的应用铺平道路，解决信息处理，传感，安全和能量收集方面的重要技术挑战。将进行四个主要研究方向。(i)场效应晶体管中的量子点网络理论，由完全可调谐的扩展Hubbard模型描述，将用于确定电子-电子相互作用是否可能导致强相关拓扑相，并允许小型量子模拟器（固态量子计算机的前体）所需的自旋电压控制。（ii）将发展嵌入纳米线的半导体量子点中电子和空穴相互作用的原子理论，以确定这些结构在单光子源和纠缠光子源、光子自旋转换以及由于调制掺杂纳米线中的e-e相互作用而形成稳健宏观量子态方面的潜力。（iii）将发展由倒带半导体（如HgTe）制成的量子点的电子和光学性质理论，并确定拓扑保护自旋分辨表面态出现所需的条件。将确定e-e相互作用在拓扑量子点的电子、光学和输运性质中的作用，以及它们在应变、电荷和自旋传感器中的应用。（iv）电子-电子相互作用、弱自旋轨道耦合的影响以及石墨烯中缺乏拓扑效应和缺乏磁性仍然是一个挑战。通过控制石墨烯的横向尺寸，人们可以打开一个能隙，将半金属石墨烯变成一个单原子层厚的“半导体”量子点，打破亚晶格对称会产生磁矩，扭曲成莫比乌斯带会引入拓扑结构。我们将开发理论和计算工具来预测石墨烯量子点的电子、光学、磁性和拓扑特性。这将允许确定用于太阳能电池的胶体量子点的光学特性，基于双层石墨烯中电子自旋的量子点网络的电子特性以及基于集成石墨烯量子点的电子电路的设计。该研究项目将推动先进量子材料、纳米结构和用于量子和低功耗信息处理、传感和能量收集的器件的进展。