Direction reversal of non-Hermitian skin effect via coherent coupling

Absolute negative mobility (ANM) in nonequilibrium systems depicts the possibility of particles propagating toward the opposite direction of an external force. We uncover in this work a phenomenon analogous to ANM regarding eigenstate localization and particle transport in non-Hermitian systems under the influence of the non -Hermitian skin effect (NHSE). A coherent coupling between two non-Hermitian chains individually possessing the same preferred direction of NHSE is shown to cause a direction reversal of NHSE for all eigenmodes. This concept is further investigated in terms of time evolution dynamics using a non-Hermitian quantum walk platform within reach of current experiments. Our findings are explained both qualitatively and quantitatively. The possible direction reversal of NHSE can potentially lead to interesting applications.

Automated summary

This work reveals a phenomenon similar to absolute negative mobility (ANM) in non-equilibrium systems, regarding eigenstate localization and particle transport. The interaction between two non-Hermitian chains with the same preferred direction causes a reversal of the non-Hermitian skin effect (NHSE) for all eigenmodes. This concept is qualitatively and quantitatively investigated in a non-Hermitian quantum walk platform.