Non-Hermitian higher-order topological states in nonreciprocal and reciprocal systems with their electric-circuit realization
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2019-05-21 |
| Journal | Physical review. B./Physical review. B |
| Authors | Motohiko Ezawa |
| Institutions | The University of Tokyo |
| Citations | 158 |
Abstract
Section titled âAbstractâA prominent feature of some one-dimensional non-Hermitian systems is that all\nright-eigenstates of the non-Hermitian Hamiltonian are localized in one end of\nthe chain. The topological and trivial phases are distinguished by the\nemergence of zero-energy modes within the skin states in the presence of the\nchiral symmetry. Skin states are formed when the system is nonreciprocal, where\nit is said nonreciprocal if the absolute values of the right- and left-going\nhoppings amplitudes are different. Indeed, the zero-energy edge modes emerge at\nboth edges in the topological phase of the reciprocal non-Hermitian system.\nThen, analyzing higher-order topological insulators in nonreciprocal systems,\nwe find the emergence of topological zero-energy modes within the skin states\nformed in the vicinity of one corner. Explicitly we explore the anisotropic\nhoneycomb model in two dimensions and the diamond lattice model in three\ndimensions. We also study an electric-circuit realization of these systems.\nElectrical circuits with (without) diodes realize the nonreciprocal\n(reciprocal) non-Hermitian topological systems. Topological phase transitions\nare observable by measuring the impedance resonance due to zero-admittance\ntopological corner modes.\n