高维自旋轨道耦合及奇异拓扑态的冷原子实现

In the past decade, the spin-orbit coupling has played the central role in the developments of several very important research topics in condensed matter physics, including spintronics and topological phases of quantum matter. On the other hand, important progresses have been made in the similar topics of the ultracold atoms by generating synthetic spin-orbit coupling, gauge field, and exotic topological states through light-atom couplings. Being extremely cleaning systems with full controllability, the cold atoms may provide ideal platforms to investigate exotic topological physics if the spin-orbit coupings similar as those in solid state systems can be generated and engineered. However, so far only 1D spin-orbit coupling has been realized in cold atom experiments, and this has a large limit in studying exotic physics with realistic cold atom systems. To find a truly feasible scheme for realizing higher dimensional spin-orbit coupling is very challenging and highly nontrivial for cold atoms. The present project aims to resolve the most important issue in this exciting topic: we shall introduce new theoretical proposals which are completely feasible in the realistic experiments to realize high dimensional spin-orbit couplings, and further predict interesting new topological states including strongly correlated topological state in the interacting regimes, and nontrivial physics based on such spin-orbit couplings. The present project shall pave the way for the experimental realization of high dimensional spin-orbit couplings and exotic topological phases for cold atoms.

自旋轨道耦合在凝聚态物理，包括自旋电子学，量子物质拓扑相等近10年来非常重要的领域扮演了核心角色。这些领域中理论和实验的重大进展使得人们对自旋轨道耦合这一基本量子效应有了全新认识。与此同时，冷原子物理近年在利用光与原子耦合产生人工自旋轨道耦合，规范场，以及奇异拓扑态等方面亦取得了重要的进展。尤其是，冷原子作为一完全可控的干净体系，在研究这些重要物理问题时具有很多优势。因此，如能在冷原子中实现类似的自旋轨道耦合作用，则可让冷原子成为研究这些奇异物理效应的一个理想平台。然而，冷原子系统目前实验实现的只有1D自旋轨道耦合，这对研究广泛的自旋轨道耦合效应及拓扑态具有极大限制。本研究项目将针对冷原子领域目前研究自旋轨道耦合和拓扑相最重要的问题开展研究，即我们将提出实验上真实可行的理论方案实现高维自旋轨道耦合，并基于所实现的自旋轨道耦合研究非平凡拓扑效应，包括关联拓扑态，实质性地推动冷原子领域的发展。

本研究项目的的背景有两方面，一是自旋轨道耦合在凝聚态物理中的自旋电子学，拓扑绝缘体，拓扑超导体等研究领域扮演了重要角色；二是相应地人工自旋轨道耦合量子模拟在超冷原子中成为重要研究领域。但在此研究项目之前，超冷原子中仅实现一维人工自旋轨道耦合（对应阿贝尔人工规范势）。这对超冷原子量子模拟形成重要局限。因此本研究项目的核心目标是推动二维及高维人工自旋轨道耦合（对应非阿贝尔势）在超冷原子中的首次实现。具体而言，本研究项目将针对冷原子领域目前研究自旋轨道耦合和拓扑相最重要的问题开展研究，即提出实验上真实可行的理论方案实现高维自旋轨道耦合，并基于所实现的自旋轨道耦合研究非平凡拓扑效应，包括关联拓扑态，实质性地推动冷原子领域的发展。所有这些目标均已达到，并实际已远超这些目标，尤其本项目导致了超冷原子中首次通过光晶格实现二维人工自旋轨道耦合，并以此广泛开展拓扑量子模拟的理论和实验研究。所完成的成果在项目研究领域已产生重大影响。本项目共完成约30篇SCI论文。其中约23篇课题负责人为通讯住作者，包括1篇Science，1篇Science Advances，1篇Nature Physics，1篇Nature Materials，6篇Phys. Rev. Lett.，1篇National Science Review等高影响权威期刊论文。