Dynamic skin effects in non-Hermitian systems

We study the time evolution processes of non-Hermitian systems under the open boundary condition and confirm that the unconventional reflection, dubbed the dynamical skin effect, exists in non-Hermitian systems analytically, and unveil the mechanism of its formation, which is caused by both the non-Hermitian skin effect and the Hermitian wave packet spreading. Furthermore, we find that in contrast to the uniform speed motion in Hermitian situations, the Gaussian wave packet can be accelerated and amplified during its time evolution in non-Hermitian systems. This additional motion is found to be responsible for the dynamic skin effect.