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

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 the PT symmetric non-Hermitian Aubry-André-Harper model. In this model, besides the non-Hermitian complex quasiperiodic on-site potential, non-Hermiticity is also included in the nearest-neighbor hopping terms. Moreover, the nearest-neighbor hopping terms are also quasiperiodic. The presence of two non-Hermitian parameters, one from the on-site 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.