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arXiv · 1702.00173

Relation between $\mathcal{PT}$-symmetry breaking and topologically nontrivial phases in the SSH and Kitaev models

Marcel Klett·Holger Cartarius·Dennis Dast·Jörg Main·Günter Wunner
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Abstract

Non-Hermitian systems with $\mathcal{PT}$ 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 $\mathcal{PT}$-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 $\mathcal{PT}$-symmetry breaking due to gain and loss with the topological phase is different for the two models. The SSH model undergoes a $\mathcal{PT}$-symmetry breaking transition in the TNP immediately with the presence of a non-vanishing gain and loss strength $γ$, whereas the TTP exhibits a parameter regime in which a purely real eigenvalue spectrum exists. For the Kitaev chain the $\mathcal{PT}$-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 $\mathcal{PT}$ symmetry in the TNP.

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Marcel Klett, Holger Cartarius, Dennis Dast, Jörg Main, Günter Wunner. 2017-05-05. Relation between $\mathcal{PT}$-symmetry breaking and topologically nontrivial phases in the SSH and Kitaev models. https://doi.org/10.1103/physreva.95.053626

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