发表机构
Department of Physics and Astronomy, College of Staten Island, CUNY; The Graduate Center, CUNY（纽约市立大学斯塔顿岛学院物理与天文系; 纽约市立大学研究生院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文发现拓扑平庸二维系统中可通过虚磁通诱导出连续谱内的手性边缘模式，其局域化源于PT对称转变而非非厄米趋肤效应，且阈值由黄金比例决定。
AI 中文摘要
拓扑物质态中的手性边缘模式通常存在于能带隙内，这些带隙可能随晶格动量发生形变和移动。本文表明，手性边缘模式也可以存在于体态能带内部，即连续谱中。这些连续谱中的手性边缘模式（CEMICs）通过向一个原本拓扑平庸的二维系统引入虚磁通量而产生，具体实现方式是在边缘施加不对称耦合。虽然较强的耦合提供了优先的循环方向，但我们发现CEMICs的边缘局域化并非源于非厄米趋肤效应，该效应通常与具有不对称耦合和开放边界条件的系统相关。相反，这种边缘局域化源于系统与环境在不对称耦合节点处的能量交换，这导致了布里渊区中的宇称-时间（PT）对称性转变。有趣的是，在宏观极限下，CEMICs的出现与系统尺寸无关，其阈值由不对称耦合与其几何平均值的黄金比例决定。
英文摘要
Chiral edge modes in topological states of matter are routinely found inside band gaps, which may be deformed and shifted as a function of the lattice momentum. Here we show that they can exist inside a bulk band instead, i.e., in the continuum. These chiral edge modes in the continuum (CEMICs) are induced by introducing an imaginary magnetic flux to an otherwise topologically trivial two-dimensional system, realized by imposing asymmetric couplings along the edge. While the stronger couplings provide a preferred circulation direction, we find that the edge localization of CEMICs does \textit{not} originate from the non-Hermitian skin effect, which is typically associated with systems featuring asymmetric couplings and the open boundary condition. Instead, this edge localization is due to the energy exchange between the system and the environment at the asymmetric coupling junctions, which leads to a parity-time (PT) transition in the Brillouin zone. Intriguingly, the onset of CEMICs is independent of the system size in the macroscopic limit, which is given by the golden ratio between the asymmetric couplings and their geometric average.
Comments8 pages, 8 figures
