2020/11/07 by C. Li, Z. Song, Li, C. +1
Mathematics · Physics and Astronomy · #Advanced Topics in Algebra #Algebraic structures and combinatorial models #Black Holes and Theoretical Physics #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Quantum Physics (quant-ph)
paper · pdf · doi:10.48550/arxiv.2011.03743
openalex publication_date 2020/11/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We study coupled non-Hermitian Rice-Mele chains, which consist of Su-Schrieffer-Heeger (SSH) chain system with staggered on-site imaginary potentials. In two dimensional (2D) thermodynamic limit, the exceptional points (EPs) are shown to exhibit topological feature: EPs correspond to topological defects of a real auxiliary 2D vector field in k space, which is obtained from the Bloch states of the non-Hermitian Hamiltonian. As a topological invariant, the topological charges of EPs can be ±1/2, obtained by the winding number calculation. Remarkably, we find that such a topological characterization remains for a finite number of coupled chains, even a single chain, in which the momentum in one direction is discrete. It shows that the EPs in the quasi-1D system still exhibit topological characteristics and can be an abridged version for a 2D system with symmetry protected EPs that are robust in perturbations, which proves that topological invariants for a quasi-1D system can be extracted from the projection of the corresponding 2D limit system on it.