New characterization of non-Hermitian skin effects

Recently, non-Hermitian systems, whose dynamics are effectively described by non-Hermitian Hamiltonians, have been extensively studied. The non-Hermitian skin effects are boundary phenomena intrinsic to non-Hermitian systems, where the energy spectra under the open boundary condition (OBC) drastically differ from those under the periodic boundary condition (PBC). In this presentation, we discuss the new characterization of non-Hermitian skin effects. We find that this characterization well-describes phase transitions of non-Hermitian skin effects with and without symmetry.