Non-Hermitian waves in a continuous periodic medium

The non-Hermitian skin effect induces the localization of bulk eigenstates at boundaries in non-Hermitian systems [1]. Although the non-Hermitian skin effect plays a crucial role, it has been studied mostly in tight-binding systems. In this work, we study waves in a non-Hermitian continuous periodic medium. Then, we find that the localization length of all the skin modes is common. In this talk, we show that this remarkable behavior can be explained in terms of the non-Bloch band theory proposed in our previous work [2]. Namely, the constant localization length reflects the circular shape of the generalized Brillouin zone. We also show that same behavior of bulk eigenstates is found in a non-Hermitian photonic crystal. [1] S. Yao and Z. Wang, Phys. Rev. Lett. 121, 086803 (2018). [2] K. Yokomizo and S. Murakami, Phys. Rev. Lett. 123, 066404 (2019).