Non-Hermitian comb effect in coupled clean and quasiperiodic chains
Phys. Rev. B 114, 024202 – Published 1 July, 2026
DOI: https://doi.org/10.1103/5vmn-vsxf
Abstract
We study localization properties in a system of non-Hermitian quasiperiodic chains coupled to a clean chain by interchain hopping. We find that in the limit of weak interchain coupling, such a coupled system exhibits transitions from delocalized to intermediate phase with increase in the non-Hermiticity parameter. However, for stronger interchain coupling strengths, the delocalized phase undergoes a transition to localized phase and then to an intermediate phase. Interestingly, the intermediate phase in this case exhibits the non-Hermitian comb effect (NHCE), i.e., the coexistence of localized and extended states rather than being well separated from each other by any mobility edge, which is conventional in any intermediate phase. We further show that such a NHCE originates from the isolated site limit of the quasiperiodic chain and provide an analytical explanation supporting the numerical signatures.
