Topological Graphene Multiterminal Josephson Junctions

拓扑石墨烯多端约瑟夫森结

• 批准号: 467596333
• 负责人: Professor Dr. Detlef Beckmann
• 金额: --
• 依托单位: Arbeitsgruppe Theorie des Quantentransports
• 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/467596333?language=en
• 关键词: Topological; Graphene; Multiterminal; Josephson; Junctions

Topological properties of quantum systems have recently attracted considerable theoretical and experimental attention. Nontrivial topological properties usually follow from intrinsic material properties, e.g., topological band structures in materials with strong spin-orbit interaction. Another possibility is the combination of different materials in hybrid structures to create topological band structures. These implementations require complex materials which are often difficult to synthesize.Recently, it has been predicted that multiterminal Josephson junctions made of conventional materials host topologically nontrivial states in an artificial band structure controlled by the macroscopic phases of the superconducting terminals. These systems offer the possibility to tune topological properties in situ by external parameters, and therefore allow considerable flexibility for the investigation of topology.The aim of this project is a joint experimental and theoretical effort to implement and understand artificial topological band structures in multiterminal Josephson junctions. The material of choice for our project is graphene. Due to its two-dimensional nature, graphene offers full flexibility of design, while its intrinsic high quality and gate tunability allows control of ballistic transport down to single quantum channels. Therefore, graphene is a prime candidate for the investigation of topological multiterminal Josephson junctions. We plan to unambiguously identify and characterize topological Andreev states via quantized nonlocal conductance and microwave spectroscopy in a minimal system, a four-terminal Josephson junction. A long-term goal is to use graphene multiterminal junctions to simulate topology in higher effective dimensions.

量子系统的拓扑性质最近引起了理论和实验的广泛关注。重要的拓扑性质通常源于内在的材料性质，例如具有强自旋轨道相互作用的材料中的拓扑能带结构。另一种可能性是在混合结构中组合不同材料以创建拓扑能带结构。这些实现需要复杂的材料，而这些材料通常难以合成。最近，有人预测，由常规材料制成的多端约瑟夫森结在由超导端子的宏观相控制的人工能带结构中具有拓扑非平凡态。这些系统提供了通过外部参数原位调整拓扑特性的可能性，因此为拓扑研究提供了相当大的灵活性。该项目的目的是联合实验和理论工作，以实现和理解多端约瑟夫森结中的人工拓扑能带结构。我们项目选择的材料是石墨烯。由于其二维性质，石墨烯提供了充分的设计灵活性，而其固有的高质量和栅极可调谐性允许控制弹道传输至单个量子通道。因此，石墨烯是研究拓扑多端约瑟夫森结的主要候选者。我们计划通过最小系统（四端约瑟夫森结）中的量化非局域电导和微波光谱来明确识别和表征拓扑安德烈夫态。长期目标是使用石墨烯多端子结来模拟更高有效维度的拓扑。