Symmetry-protected localized states at defects in non-Hermitian systems

Abstract

Understanding how local potentials affect system eigenmodes is crucial for experimental studies of nontrivial bulk topology. Recent studies have discovered many exotic and highly non-trivial topological states in non-Hermitian systems. As such, it would be interesting to see how non-Hermitian systems respond to local perturbations. In this work, we consider chiral and particle-hole -symmetric non-Hermitian systems on a bipartite lattice, including SSH model and photonic graphene, and find that a disordered local potential could induce bound states evolving from the bulk. When the local potential on a single site becomes infinite, which renders a lattice vacancy, chiral-symmetry-protected zero-energy mode and particle-hole symmetry-protected bound states with purely imaginary eigenvalues emerge near the vacancy. These modes are robust against any symmetry-preserved perturbations. Our work generalizes the symmetry-protected localized states to non-Hermitian systems.

arXiv comment8 pages, 9 figures

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• Topological Correspondence between Hermitian and Non-Hermitian Systems: Anomalous Dynamics
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• Topological semimetal phase with exceptional points in one-dimensional non-Hermitian systems
• Non-Hermitian Topological Metamaterials with Odd Elasticity
• Inversion symmetric non-Hermitian Chern insulator
• Flat-band-based multifractality in the all-band-flat diamond chain
• The topological counterparts of non-Hermitian SSH models
• Diagnosis of bulk phase diagram of non-reciprocal topological lattices by impurity modes
• Non-Hermitian impurities in Dirac systems
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• Linear localization of zero modes in weakly coupled non-Hermitian reservoirs
• Observing complementary Lucas sequences using non-Hermitian zero modes