论文标题
观察自旋调整诱导的拓扑拓扑相变，带有捕获的离子
Observation of spin-tensor induced topological phase transitions of triply degenerate points with a trapped ion
论文作者
论文摘要
与新型的拓扑半学类型相对应的三重归化点（TDP）可以支持具有有效整数旋转的新型准颗粒，同时保留费米统计。在这里，通过将动量空间映射到被困离子中三级系统的参数空间，我们通过实验探索了由旋转tensor-momentum耦合驱动的不同类型的TDP之间的过渡。我们通过测量围绕间隙闭合线的环上的浆果通量来观察具有不同拓扑电荷的TDP之间的相变，而浆果通量的跳跃可以使拓扑充电（最高$2π$因子）在整个过渡中的跳跃。对于浆果通量测量，我们通过检查旋转矢量和张量的几何旋转来采用一种新方法，从而导致广义的实体角等于浆果通量。多层离子的可控性提供了一个多功能平台来研究高旋转物理学，我们的工作为探索新颖的拓扑现象的方式铺平了道路。
Triply degenerate points (TDPs), which correspond to new types of topological semimetals, can support novel quasiparticles possessing effective integer spins while preserving Fermi statistics. Here by mapping the momentum space to the parameter space of a three-level system in a trapped ion, we experimentally explore the transitions between different types of TDPs driven by spin-tensor--momentum couplings. We observe the phase transitions between TDPs with different topological charges by measuring the Berry flux on a loop surrounding the gap-closing lines, and the jump of the Berry flux gives the jump of the topological charge (up to a $2π$ factor) across the transitions. For the Berry flux measurement, we employ a new method by examining the geometric rotations of both spin vectors and tensors, which lead to a generalized solid angle equal to the Berry flux. The controllability of multi-level ion offers a versatile platform to study high-spin physics and our work paves the way to explore novel topological phenomena therein.
