2020/08/31 by Kohei Kawabata, Masatoshi Sato, Ken Shiozaki · 5 citations
Physics and Astronomy · Mathematics · #cond-mat.mes-hall #math-ph #math.MP #physics.optics #quant-ph
paper · pdf · doi:10.1103/physrevb.102.205118
published as Phys. Rev. B 102, 205118 (2020) · 17 pages, 6 figures; selected as PRB Editors' Suggestion
arxiv created 2020/11/17 · arxiv updated 2020/11/18
The non-Hermitian skin effect is a unique feature of non-Hermitian systems, in which an extensive number of boundary modes appear under the open boundary conditions. Here, we discover higher-order counterparts of the non-Hermitian skin effect that exhibit new boundary physics. In two-dimensional systems with the system size L × L, while the conventional (first-order) skin effect accompanies O ( L2 ) skin modes, the second-order skin effect accompanies O ( L ) corner skin modes. This also contrasts with Hermitian second-order topological insulators, in which only O ( 1 ) corner zero modes appear. Moreover, for the third-order skin effect in three dimensions, O ( L ) corner skin modes appear from all O ( L3 ) modes. We demonstrate that the higher-order skin effect originates from intrinsic non-Hermitian topology protected by spatial symmetry. We also show that it accompanies the modification of the non-Bloch band theory in higher dimensions.