量子受限超导体系中Majorana束缚态和拓扑缺陷性质研究

Novel quantum effects in confined superconducting systems as well as their practical applications become a very promising research domain. Based on our previous works, the project aims at a theoretical investigation of the zero-energy Majorana bound states and topological defects in superconducting systems with quantum confinement effects in the framework of the microscopic Bogoliubov-de Gennes theory. Through considering proper physical models, the quantum features of the confined systems will be studied systematically. Main expected results are summarized as follows：.(1) We first try to build mesoscopic multi-connected topological superconducting systems, and investigate the existence and nontrivialty of the Majorana bound states. Then, we demonstrate the corresponding evolution of currents and the quantum phase transitions, and propose more efficient application methods based on our investigations;.(2) We investigate further the properties of the vortex, antivortex and skyrmion in mesoscopic chiral p-wave superconducting systems, and reveal the fundamental principles as well as related experimental manipulation, and then envisage new methods of quantum controlling;.(3) We turn to analysis in detail the novel electronic properties and emerging topological states in multicomponent(-like) superconducting systems (such as the ultra-thin superconducting films), and provide a comprehensive review of how to achieve them in experiments, and then offer ways to construct novel nanomaterials and develop new types of quantum electronic devices.

受限超导体系中新奇量子效应因其广泛应用前景已成为当前研究热点之一。在前期研究基础上，本项目主要基于有效的微观Bogoliubov-de Gennes 理论框架，建立合适物理模型，系统深入研究量子受限超导体系中Majorana零能束缚态和拓扑缺陷性质，拟取得以下主要成果：（1）合理构建介观多连通拓扑超导系统，明确Majorana束缚态的存在性和非平凡性，给出相应电流演化及量子相变规律，探索Majorana零能模式和拓扑相变的应用方案；（2）全面理解介观手征p波超导系统中涡旋、反涡旋及斯格明子等拓扑缺陷态特征，揭示其基本规律，通过对各类拓扑缺陷态的操纵，提出量子调控新方法；（3）进一步分析类似多分量超导体系（如超导纳米薄膜等）中新奇电子性质以及拓扑态呈现，提供实验探测依据，为未来新型纳米材料的构建以及量子电子器件的开发等提供参考和基础理论储备。

受限超导体系中新奇量子效应因其广泛应用前景已成为当前研究热点之一。本项目主要基于有效的Bogoliubov-de Gennes 理论框架，建立合适物理模型，系统研究了介观超导体系中的新奇物质态，取得了以下主要成果：.（1) 深刻理解了介观非常规p波超导体系中新奇量子态（如手征畴壁态、Majorana零能态、无芯skyrmion态等）的基本属性和演化规律。呈现出的新奇拓扑缺陷结构会受到样品几何、外加磁场、温度以及磁性或非磁性杂质的强烈影响。多重畴壁态、多重skyrmion态、拓扑电荷Q>2的skyrmion态以及伴随有半磁通量子涡旋-反涡旋配对的skyrmion链等奇特结构都会在系统中相继出现。该类结果对未来新型量子电子器件的研究与开发有重要基础意义。.（2）通过考虑自旋关联效应及调节系统化学势，深入研究了多序共存情形下的介观超导系统中新奇涡旋态和磁通演化模式。由于多序竞争效应，在自旋三重态p波主导、自旋单态d波共存的混合配对序体系中会稳定存在单拓扑电荷的skyrmion态。同时，p波序中会出现非常规的类椭圆涡旋结构，而d波序中会存在拉长的新奇涡旋空间模式。该类结果能够很好地澄清实验反常现象，并为进一步寻找skyrmion等量子态及其操控方案提供了参考和理论支撑。.（3）成功构建了多分量或多带超导系统，深入探讨该类体系中的奇特配对态性质和磁通周期性演化。对于介观及纳米s波超导正方样品，自旋-轨道耦合作用能使超导能级产生显著分裂。引入的磁性杂质或杂质层会引起能带内束缚态，进而在某些合适的杂质强度时能隙会闭合。与此对应，自旋电流在零能点处会发生跃变，表现出新奇的磁通演化情形。该类结果很好地揭示拓扑超导体系中电流演化及量子相变的基本规律，为探索新型量子电子器件提供新的思路。