Two-dimensional non-Hermitian Su-Schrieffer-Heeger Model

TL;DR

This paper explores a 2D non-Hermitian SSH model with gain and loss, revealing exceptional points, quantized Zak phase, and potential for extended bulk-boundary correspondence in experimental photonic and acoustic systems.

Contribution

It introduces a particle-hole symmetry protected non-Hermitian 2D SSH model with complex potentials and analyzes its topological properties and exceptional points.

Findings

Exceptional points occur near unity potential and hopping amplitudes.

Quantized vectored Zak phase is obtained.

Analysis of a topolectric RLC circuit demonstrates potential experimental realization.

Abstract

A particle-hole symmetry protected 2D non-Hermitian Su-Schrieffer-Heeger (SSH) model is investigated. This version differs from the usual Hermitian version by the inclusion of gain and/or loss terms which are represented by complex on-site potentials. The exceptional points occur, when the dimensionless potential magnitude and the hopping amplitudes become close to unity, leading to the coalescence of eigenvalues and nontrivial eigenvector degeneracies. Furthermore, the vectored Zak phase quantization has been obtained and a topolectric RLC circuit has been analysed. If realized experimentally (in photonic and acoustic crystals), the quantization is expected to lead to an extended bulk-boundary correspondence.