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.

8 pages, 9 figures

References in corpus (14)

• Making Sense of Non-Hermitian Hamiltonians
• Loss-induced suppression and revival of lasing
• PT-symmetry breaking and laser-absorber modes in optical scattering systems
• Edge Modes, Degeneracies, and Topological Numbers in Non-Hermitian Systems
• PT-Symmetric Phonon Laser
• Topological phases in the non-Hermitian Su-Schrieffer-Heeger model
• Topological Transition in a Non-Hermitian Quantum Walk
• PT-Symmetry in Non-Hermitian Su-Schrieffer-Heeger model with complex boundary potentials
• Extremal transmission at the Dirac point of a photonic band structure
• Topological invariance and global Berry phase in non-Hermitian systems
• Entanglement and spin squeezing in non-Hermitian phase transitions
• An Index Theorem for the Majorana Zero Modes in Chiral P-Wave Superconductors
• Z2 invariant protected bound states in topological insulators
• Creation and manipulation of anyons in a layered superconductor-2DEG system