Circuit realization of a two-orbital non-Hermitian tight-binding chain

Abstract

We examine a non-Hermitian (NH) tight-binding system comprising two orbitals per unit cell and their electrical circuit analogs. We distinguish the $\mathcal{PT}$-symmetric and non-$\mathcal{PT}$-symmetric cases characterized by nonreciprocal nearest-neighbor couplings and on-site gain and loss terms, respectively. The localization of the edge modes or the emergence of the topological properties is determined via the maximum inverse participation ratio, which has distinct dependences on the parameters that define the Hamiltonian. None of the above scenarios exhibit the non-Hermitian skin effect. We investigate the boundary modes corresponding to the topological phases in a suitably designed electrical circuit by analyzing the two-port impedance and retrieve the admittance band structure of the circuit by imposing periodic boundary conditions. The obtained results are benchmarked against the Hermitian version of the two-orbital model to compare with and differentiate from those obtained for the NH variants.

Topics & Concepts