Topological Origin of Non-Hermitian Skin Effects

A unique feature of non-Hermitian systems is the skin effect, which is the extreme sensitivity to the boundary conditions. Here, we reveal that the skin effect originates from intrinsic non-Hermitian topology. Such a topological origin not merely explains the universal feature of the known skin effect, but also leads to new types of the skin effects-symmetry-protected skin effects. In particular, we discover the Z_{2} skin effect protected by time-reversal symmetry. On the basis of topological classification, we also discuss possible other skin effects in arbitrary dimensions. Our work provides a unified understanding about the bulk-boundary correspondence and the skin effects in non-Hermitian systems.

• JS
  Japan Society for the Promotion of Science

  Awards: JP18J01610, JP15H05855, JP17H02922, JP19J21927
• JS
  Japan Science and Technology Agency

  Awards: JPMJCR19T2, JPMJPR18L4