Hybrid exceptional point created from type III Dirac point

TL;DR

This paper introduces a novel hybrid exceptional point formed from merging two EP2s with opposite chiralities originating from type III Dirac points in a flat band, revealing new topological features and interference effects.

Contribution

It demonstrates the creation of hybrid EP2s from type III Dirac points and explores their topological and interference properties, advancing understanding of non-Hermitian topological phases.

Findings

Hybrid EP2s formed from merging two EP2s with opposite chiralities.

Topological features distinguish degeneracy points via geometric phase and phase rigidity.

Destructive interference induces isolated band touching hybrid EP2.

Abstract

Degeneracy (exceptional) points embedded in energy band are distinct by their topological features. We report different hybrid two-state coalescences (EP2s) formed through merging two EP2s with opposite chiralities that created from the type III Dirac points emerging from a flat band. The band touching hybrid EP2, which is isolated, is induced by the destructive interference at the proper match between non-Hermiticity and synthetic magnetic flux. The degeneracy points and different types of exceptional points are distinguishable by their topological features of global geometric phase associated with the scaling exponent of phase rigidity. Our findings not only pave the way of merging EPs but also shed light on the future investigations of non-Hermitian topological phases.