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

TL;DR

This paper explores the realization of a two-orbital non-Hermitian tight-binding model using electrical circuits, analyzing topological edge modes, their localization, and the absence of the skin effect, with experimental verification through impedance measurements.

Contribution

It introduces a circuit-based implementation of a two-orbital non-Hermitian model, distinguishing PT-symmetric and non-PT symmetric cases and analyzing their topological properties.

Findings

Edge modes are localized without skin effect.

Impedance measurements reveal the admittance band structure.

Topological phases are successfully characterized in circuit analogues.

Abstract

We examine a non-Hermitian (NH) tight-binding system comprising of two orbitals per unit cell and their electrical circuit analogues. We distinguish the PT-symmetric and non-PT symmetric cases characterised by non-reciprocal nearest neighbour couplings and onsite gain/loss terms, respectively. The localisation of the edge modes or the emergence of the topological properties are determined via the maximum inverse participation ratio, which has distinct dependencies on the parameters that define the Hamiltonian. None of the above scenarios exhibits 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 via imposing periodic boundary conditions. The obtained results are benchmarked against the Hermitian version of the two-orbital model to compare and discriminate against those obtained for the NH variants.