近日，山西大学张静团队实现了狄拉克点原子玻色-爱因斯坦凝聚体中自旋-轨道耦合的量子化涡旋观测。该项研究成果发表在2025年9月29日出版的《自然—光子学》杂志上。
在能带结构的奇点处，如狄拉克点，两个或多个能带的简并，产生了有趣的量子现象以及非物质性质。狄拉克点上的系统可以具有拓扑电荷，它们的独特性质可以通过各种方法来探测，如输运测量、干涉测量和动量光谱。虽然动量空间中狄拉克点的拓扑结构在理论上已经得到了很好的研究，但在狄拉克点上观察多体量子系统的拓扑缺陷仍然是一个难以实现的目标。
基于石墨烯类光学蜂窝晶格中的原子玻色-爱因斯坦凝聚，研究组直接观察到狄拉克点上谐波阱和伪自旋-轨道耦合之间的非交换性引起的量子化漩涡的出现。通过对蜂窝晶格进行绝热控制，外加谐波俘获势，研究组揭示了晶格玻色子在狄拉克点的相图。该工作提供了一种在量子气体中产生涡旋的新方法，该方法是通用的，可以应用于具有拓扑奇点的不同类型的光学晶格，包括扭曲双层光学晶格中狄拉克点附近的拓扑平坦带。
附：英文原文
Title: Observation of quantized vortex in atomic Bose–Einstein condensate at Dirac point with emergent spin–orbit coupling
Author: Li, Yunda, Han, Wei, Meng, Zengming, Yang, Wenxin, Chin, Cheng, Zhang, Jing
Issue&Volume: 2025-09-29
Abstract: The degeneracy of two or more energy bands at a singular point in the band structure, such as a Dirac point, gives rise to intriguing quantum phenomena as well as unusual material properties. Systems at the Dirac points can possess topological charges and their unique properties can be probed by various methods, such as transport measurement, interferometry and momentum spectroscopy. While the topology of Dirac point in the momentum space is well studied theoretically, observation of topological defects in a many-body quantum system at Dirac point remains an elusive goal. Based on atomic Bose–Einstein condensate in a graphene-like optical honeycomb lattice, we directly observe emergence of quantized vortices induced by the non-commutativity between the harmonic trap and the pseudo-spin–orbit coupling at the Dirac point. By adiabatic control of the honeycomb lattice with an additional harmonic trapping potential, the phase diagram of lattice bosons at the Dirac point is revealed. Our work provides a new way of generating vortices in a quantum gas, and the method is generic and can be applied to different types of optical lattices with topological singularities, including topological flat bands near Dirac points in twisted bilayer optical lattices.
DOI: 10.1038/s41566-025-01763-5
Source: https://www.nature.com/articles/s41566-025-01763-5