Construction and Observation of Flexibly Controllable High-Dimensional Non-Hermitian Skin Effects

• Main Authors: Zhang, Qicheng, Leng, Yufei, Xiong, Liwei, Li, Yuzeng, Zhang, Kun, Qi, Liangjun, Qiu, Chunyin
• Format: Journal Article
• Language: English
• Published: 31.05.2024
• Subjects: Physics - Applied Physics; Physics - Classical Physics; Physics - Materials Science; Physics - Other Condensed Matter
• DOI: 10.48550/arxiv.2406.02593

Advanced Materials, 2403108 (2024) Non-Hermitian skin effect (NHSE) is one of the most fundamental phenomena in non-Hermitian physics. Although it is established that one-dimensional NHSE originates from the nontrivial spectral winding topology, the topological origin behind the higher-dimensional NHSE remains unclear so far. This poses a substantial challenge in constructing and manipulating high-dimensional NHSEs. Here, an intuitive bottom-to-top scheme to construct high-dimensional NHSEs is proposed, through assembling multiple independent one-dimensional NHSEs. Not only the elusive high-dimensional NHSEs can be effectively predicted from the well-defined one-dimensional spectral winding topologies, but also the high-dimensional generalized Brillouin zones can be directly synthesized from the one-dimensional counterparts. As examples, two two-dimensional nonreciprocal acoustic metamaterials are experimentally implemented to demonstrate highly controllable multi-polar NHSEs and hybrid skin-topological effects, where the sound fields can be frequency-selectively localized at any desired corners and boundaries. These results offer a practicable strategy for engineering high-dimensional NHSEs, which could boost advanced applications such as selective filters and directional amplifiers.