paper

Relation between -symmetry breaking and topologically nontrivial phases in the SSH and Kitaev models

arXiv:1702.00173 · doi:10.1103/PhysRevA.95.053626

Abstract

Non-Hermitian systems with symmetry can possess purely real eigenvalue spectra. In this work two one-dimensional systems with two different topological phases, the topological nontrivial Phase (TNP) and the topological trivial phase (TTP) combined with -symmetric non-Hermitian potentials are investigated. The models of choice are the Su-Schrieffer-Heeger (SSH) model and the Kitaev chain. The interplay of a spontaneous -symmetry breaking due to gain and loss with the topological phase is different for the two models. The SSH model undergoes a -symmetry breaking transition in the TNP immediately with the presence of a non-vanishing gain and loss strength , whereas the TTP exhibits a parameter regime in which a purely real eigenvalue spectrum exists. For the Kitaev chain the -symmetry breaking is independent of the topological phase. We show that the topological interesting states -- the edge states -- are the reason for the different behaviors of the two models and that the intrinsic particle-hole symmetry of the edge states in the Kitaev chain is responsible for a conservation of symmetry in the TNP.

7 pages, 5 figures, additional references, minor changes in the text

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