基于超冷原子体系的拓扑态量子模拟与调控

Ultracold atoms are considered as ideal systems for quantum simulation due to their high tunability. These systems provide a brand new platform to explore the complex phenomena in condensed matter physics and to develop novel quantum devices. Topological quantum states nowadays become a research front in condensed matter physics, which are important both in academic and application prospects. However, many kinds of topological states are yet to be realized. This project, therefore, aims to explore the physics of some exotic topological states and their quantum simulation in ultracold atom systems, which mainly includes the following contents. (1) In cold atom systems, by designing suitable artificial magnetic field and spin-orbit coupling structures, we plan to propose the simulation of topological Weyl, nodal-line, and Z2 semimetal states with the related novel effects. (2) Based on the quantum dynamical processes of cold atomic quantum pumping and linear response, we plan to develop feasible methods for detecting the topological properties of the simulated topological states, such as the Z2 index. (3) Finally in cold atoms systems, we plan to study how to manipulate Weyl quasiparticles for realizing topological phase transition and chiral Hall devices, and investigate how to manipulate some topological excitations (such as Marajora quasiparticles) for testing the non-Abelian exchange statistics. This project will focus on feasible schemes for realization, detection, and manipulation of exotic topological states in cold atom systems, which will expand the research of topology phenomena in condensed matter systems and provide theoretical support for future experimental studies.

超冷原子具有高度可控性，是实现量子模拟的理想体系，为探索复杂凝聚态物理现象以及开发新型量子器件提供崭新的平台。拓扑量子态是当前凝聚态物理的研究前沿，具有重要的学术价值与应用前景，然而许多拓扑态很难在固体材料中实现。因而，本项目旨在探索新奇拓扑态的物理特性及其在超冷原子体系中的量子模拟问题，拟主要研究如下内容：（1）在冷原子体系中通过设计合适的人工磁场或自旋轨道耦合结构，模拟拓扑外尔、Nodal-line与Z2半金属态及其新颖效应；（2）基于冷原子量子泵浦和线性响应的量子动力学过程，发展可行方法探测上述拓扑态的Z2指标等拓扑性质；（3）探索操控冷原子体系中的外尔准粒子，实现拓扑相变和开发手征霍尔器件，以及操控马约拉纳(Marajora) 准粒子等拓扑激发，检验非阿贝尔统计特性。本项目致力于提出实现、探测和操控新奇拓扑态的冷原子方案，扩展凝聚态体系拓扑现象的研究，为实验研究提供理论支持。

超冷原子具有高度可控性，是实现量子模拟的理想体系，为探索复杂凝聚态物理现象以及开发新型量子器件提供崭新的平台。拓扑量子态是当前凝聚态物理的研究前沿，具有重要的学术价值与应用前景，然而许多拓扑态很难在固体材料中实现。本项目旨在探索新奇拓扑态的物理特性及其在超冷原子体系中的量子模拟问题，主要研究内容和取得的重要成果包括：（1）提出了几种新奇拓扑物态冷原子实现方案，包括冷原子模拟不同外尔半金属、Nodal-line半金属与新型Maxwell拓扑金属等无能隙拓扑态，以及实现三维推广的Hofstadter模型及其新奇的三维量子霍尔效应的可行方案。（2）提出了冷原子和超导人工原子体系拓扑性质的可行探测方法，包括提出了基于冷原子量子泵浦探测拓扑能带的拓扑性质；提出了基于线性响应的非绝热量子动力学方法，探测冷原子体系的拓扑性质，并将此方法推广到了高自旋系统，利用此方法在超导人工原子实验中直接测量陈数大于1的拓扑荷；提出了基于淬火直接测量量子度规的方案，并在超导人工原子中实验实现。（3）提出了冷原子拓扑物态中准粒子的操控，主要包括操控外尔准粒子的方法，实现拓扑相变和模拟手征磁效应等拓扑现象；理论预言了有噪声情况下的动力学量子相变过程中拓扑激发的标度行为出现anti-Kibble-Zurek机制。项目执行期间，共发表标注基金的论文19篇，其中SCI论文17篇。项目负责人作为（共同）第一或通讯作者论文发表的代表性论文包括：Advances in Physics 1篇，Physical Review Letters 2篇，Physical Review系列8篇，Optical Express 1篇，Physics Letters A 2篇。本项目的科学意义在于提出实现、探测和操控新奇拓扑量子物态的冷原子方案，扩展凝聚态体系拓扑现象的研究，为实验研究提供理论支持，例如提出的Maxwell拓扑金属能带的模拟与探测以及量子度规的测量方案已在超导人工原子体系中实验实现。