论文标题
直接测量混合光 - 摩擦系统中的非阵程拓扑不变
Direct Measurement of a Non-Hermitian Topological Invariant in a Hybrid Light-Matter System
论文作者
论文摘要
拓扑是理解和工程材料的核心，这些材料表现出强大的物理现象不受瑕疵的影响。物质的不同拓扑阶段的特征是拓扑不变。在能量持续的（Hermitian）系统中，这些不变性是由特征态在动量空间中的绕组决定的。在非热系统的系统中，预计复杂的特征力易能的缠绕中会出现一种新型的拓扑不变。在这里，我们直接测量了由激励层层状谱谱中特殊点产生的非拓扑拓扑不变的。这些是在室温下在卤化物钙钛矿半导体中强烈耦合到电子孔对（激子）的光子形成的杂交光 - 物质。我们在实验中绘制了频谱的真实（能量）和假想（线宽）部分附近的差异，并提取新的拓扑不变的分数光谱绕组。我们的工作代表了在凝结物质系统中实现非热拓扑阶段的重要一步。
Topology is central to understanding and engineering materials that display robust physical phenomena immune to imperfections. Different topological phases of matter are characterised by topological invariants. In energy-conserving (Hermitian) systems, these invariants are determined by the winding of eigenstates in momentum space. In non-Hermitian systems, a novel topological invariant is predicted to emerge from the winding of the complex eigenenergies. Here, we directly measure the non-Hermitian topological invariant arising from exceptional points in the momentum-resolved spectrum of exciton polaritons. These are hybrid light-matter quasiparticles formed by photons strongly coupled to electron-hole pairs (excitons) in a halide perovskite semiconductor at room temperature. We experimentally map out both the real (energy) and imaginary (linewidth) parts of the spectrum near the exceptional points and extract the novel topological invariant - fractional spectral winding. Our work represents an essential step towards realisation of non-Hermitian topological phases in a condensed matter system.
