Bulk-edge correspondence for point-gap topological phases in junction systems

Abstract

The bulk-edge correspondence is one of the most important ingredients in the theory of topological phases of matter. While the bulk-edge correspondence is applicable for Hermitian junction systems where two subsystems with independent topological invariants are connected to each other, it has not been discussed for junction systems with non-Hermitian point-gap topological phases. In this Letter, based on analytical results obtained by the extension of non-Bloch band theory to junction systems, we establish the bulk-edge correspondence for point-gap topological phases in junction systems. We also confirm that almost all the eigenstates are localized near the interface which are called the ``non-Hermitian proximity effects''. One of the unique properties is that the localization length becomes the same for both subsystems, nevertheless those model parameters are different.