Topological triple phase transition in non-Hermitian quasicrystals with complex asymmetric hopping

TL;DR

This paper investigates a non-Hermitian quasicrystal model exhibiting simultaneous topological, PT symmetry breaking, and metal-insulator phase transitions, with potential experimental realization via electrical circuits.

Contribution

It introduces a non-Hermitian extension of the Aubry-André-Harper model with complex asymmetric hopping, revealing triple phase transitions and proposing an electrical circuit implementation.

Findings

Observation of triple phase transitions in the model

Identification of parameter regimes for simultaneous transitions

Proposal for experimental realization using electrical circuits

Abstract

The triple phase transitions or simultaneous transitions of three different phases, namely topological, parity-time (PT) symmetry breaking, and metal-insulator transitions, are observed in an extension of PT symmetric non-Hermitian Aubry-Andr\'e-Harper model. In this model, besides non-Hermitian complex quasi-periodic onsite potential, non-Hermiticity is also included in the nearest-neighbor hopping terms. Moreover, the nearest-neighbor hopping terms is also quasi-periodic. The presence of two non-Hermitian parameters, one from the onsite potential and another one from the hopping part, ensures PT symmetry transition in the system. In addition, tuning these two non-Hermitian parameters, we identify a parameters regime, where we observe the triple phase transition. Following some recent studies, an electrical circuit based experimental realization of this model is also discussed.