Engineered Complex Edges of Fractional Quantum Hall Phases: Coherence, Topology, and Non-Equilibrium

分数量子霍尔相的工程复杂边缘：相干性、拓扑和非平衡

• 批准号: 320540272
• 负责人: Professor Dr. Alexander Mirlin
• 金额: --
• 依托单位: Institut für QuantenMaterialien und Technologien (IQMT)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/320540272?language=en
• 关键词: Engineered; Complex; Edges; Fractional; Quantum

Fractional quantum Hall (FQH) systems represent a remarkable playground to study fundamental quantum phenomena, such as interference and decoherence, topological quantization, entanglement, charge fractionalization, and fractional and non-abelian statistics. Low-lying excitations of FQH systems are located at the edge. Especially rich physics is displayed by FQH edges with counterpropagating modes. Coulomb interaction and disorder at the edge play a prominent role, leading to mode fractionalization and to the emergence of neutral modes propagating “upstream”, along with charged modes propagating “downstream”. Within the preceding project we have demonstrated that there are two distinct transport regimes—coherent and incoherent. Both regimes are characterized by a separation of charge and neutral modes, with the latter carrying energy. However, properties of the neutral modes, and the resulting transport properties, are very different. We have shown that transport observables in both regimes reflect bulk topology and that nearly all previous experiments were done in the incoherent regime. Our collaboration with WIS experimental group has permitted to devise an experimental setup based on an engineered edge that has demonstrated the crossover from the coherent to incoherent regime predicted by our theory. These novel experimental discoveries lead to promising platforms for engineering and controlling a variety of complex FQH edges and exploring their transport properties in various regimes. This serves as one of key motivations for the present project. First, we will explore partially coherent regimes of transport which are characterized by partial equilibration at the edge. Such regimes should emerge in parametrically broad range of parameters for a variety of experimentally relevant settings. Our preliminary results show that partially equilibrated regimes lead to qualitatively novel topological physics. We will analyze charge and heat conductances, shot noise, and energy-resolved transport spectroscopy, extending the study also to non-abelian edges and geometries with quantum point contacts. Second, we will investigate novel artificially designed phases on the edge described by non-trivial renormalization fixed points. Such phases may be designed on engineered edges that are characterized a hierarchy of inter-mode couplings. Finally, we will explore quantum interference phenomena involving elementary excitations of the new engineered phases on the edge, including Mach-Zehnder, Hanbury-Brown-Twiss, and Hong-Ou-Mandel interferometry. Such quantum interference of non-trivial quasi-particles is of fundamental as well as of potential technological importance. The work will be carried out in close cooperation with experimental groups of M. Heiblum (WIS) and A. Das (IISc) exploring semiconductor and graphene structures, respectively.

分数阶量子霍尔（Fractional quantum Hall，简称FQH）系统是研究量子基本现象的一个重要平台，如干涉与退相干、拓扑量子化、纠缠、电荷分数化、分数阶统计与非阿贝尔统计等。低激发的DSPH系统位于边缘。特别是丰富的物理表现为具有反向传播模式的双折射边缘。库仑相互作用和无序的边缘起着突出的作用，导致模式的分裂和出现的中性模式传播“上游”，沿着与带电模式传播“下游”。在前面的项目中，我们已经证明了有两种不同的传输机制--相干和不相干。这两种制度的特点是分离的电荷和中性模式，后者携带能量。然而，中性模式的性质以及由此产生的输运性质是非常不同的。我们已经表明，在这两个政权的运输可观的反映散装拓扑结构，几乎所有以前的实验都在非相干政权。我们与WIS实验组的合作已经允许设计一个基于工程边缘的实验装置，该边缘已经证明了我们的理论所预测的从相干到非相干状态的交叉。这些新的实验发现导致有前途的平台工程和控制的各种复杂的BARCH边缘，并探索其在各种制度的传输特性。这是本项目的主要动机之一。首先，我们将探讨部分相干制度的运输，其特点是部分平衡的边缘。这样的制度应该出现在参数广泛的参数范围内的各种实验相关的设置。我们的初步结果表明，部分平衡制度导致定性新颖的拓扑物理。我们将分析电荷和热传导，散粒噪声和能量分辨输运光谱，将研究扩展到非阿贝尔边缘和量子点接触的几何形状。其次，我们将研究新的人工设计的非平凡重整化不动点所描述的边缘相位。这样的相位可以被设计在以模式间耦合的层级为特征的工程边缘上。最后，我们将探讨量子干涉现象，包括马赫-曾德尔，汉伯里-布朗-特维斯和洪-欧-曼德尔干涉术的边缘上的新工程阶段的基本激发。这种非平凡准粒子的量子干涉具有基本的和潜在的技术重要性。这项工作将与M. Heiblum（WIS）和A. Das（IISc）分别探索半导体和石墨烯结构。