Researchers from the Beijing Computational Science Research Center, including Xue-Min Yang, Hao Lin, Jian Li, Jia-Ji Zhu, Jun-Li Zhu, and Hong Wu, have published a study that challenges conventional understanding of non-Hermitian topological insulators and establishes a new framework for understanding their properties.
The study focuses on non-Hermitian systems, which are systems that do not conserve energy, unlike Hermitian systems. The researchers specifically examined a two-dimensional non-Hermitian Su-Schrieffer-Heeger model, which is a theoretical model used to describe certain types of topological insulators. The researchers found that, contrary to previous beliefs, the zero-mode corner states in these systems are not robust to infinitesimal perturbations that preserve chiral symmetry in large-sized systems.
To better understand the higher-order topology of non-Hermitian systems, the researchers established a correspondence between stable zero-mode singular states and topologically protected corner states of energy spectrum in the thermodynamic limit. This means that the number of zero-mode singular values is directly linked to the number of mid-gap corner states. The researchers also defined winding numbers in real space to count the number of stable zero-mode singular states.
The study’s findings formulate a bulk-boundary correspondence for both static and Floquet non-Hermitian systems. This means that the topology of these systems arises intrinsically from the non-Hermiticity, even without symmetries. The research was published in the journal Physical Review Letters.
The practical applications of this research for the energy sector are not immediately clear, as the study is primarily theoretical in nature. However, a deeper understanding of non-Hermitian systems and their properties could potentially lead to new developments in energy storage and transfer, as well as other areas of energy research. The energy industry often relies on complex systems that can exhibit non-Hermitian behavior, and a better understanding of these systems could lead to more efficient and effective energy technologies.
This article is based on research available at arXiv.