Franca Selma, Könye Viktor, Hassler Fabian, van den Brink Jeroen, Fulga Cosma
Institute for Theoretical Solid State Physics, IFW Dresden and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtzstrasse 20, 01069 Dresden, Germany.
JARA-Institute for Quantum Information, RWTH Aachen University, 52056 Aachen, Germany.
Phys Rev Lett. 2022 Aug 19;129(8):086601. doi: 10.1103/PhysRevLett.129.086601.
Physically, one tends to think of non-Hermitian systems in terms of gain and loss: the decay or amplification of a mode is given by the imaginary part of its energy. Here, we introduce an alternative avenue to the realm of non-Hermitian physics, which involves neither gain nor loss. Instead, complex eigenvalues emerge from the amplitudes and phase differences of waves backscattered from the boundary of insulators. We show that for any strong topological insulator in a Wigner-Dyson class, the reflected waves are characterized by a reflection matrix exhibiting the non-Hermitian skin effect. This leads to an unconventional Goos-Hänchen effect: due to non-Hermitian topology, waves undergo a lateral shift upon reflection, even at normal incidence. Going beyond systems with gain and loss vastly expands the set of experimental platforms that can access non-Hermitian physics and show signatures associated with non-Hermitian topology.
从物理角度来看，人们往往会从增益和损耗的角度来思考非厄米系统：模式的衰减或放大由其能量的虚部给出。在此，我们引入了一条通往非厄米物理领域的替代途径，该途径既不涉及增益也不涉及损耗。相反，复本征值源自从绝缘体边界反向散射的波的振幅和相位差。我们表明，对于维格纳 - 戴森类中的任何强拓扑绝缘体，反射波的特征是具有非厄米趋肤效应的反射矩阵。这导致了一种非常规的古斯 - 汉欣效应：由于非厄米拓扑结构，即使在正入射时，波在反射时也会发生横向位移。超越具有增益和损耗的系统极大地扩展了能够研究非厄米物理并展示与非厄米拓扑相关特征的实验平台的范围。
