Non-Hermitian skin effect denotes the exponential localization of a large number of eigen-states at boundaries in a non-Hermitian lattice under open boundary conditions. Such a non-Hermiticity-induced skin effect can offset the penetration depth of in-gap edge states, leading to counterintuitive delocalized edge modes, which have not been studied in a realistic photonic system such as photonic crystals. Here, we analytically reveal the non-Hermitian skin effect and the delocalized edge states in Maxwell's equations for non-Hermitian chiral photonic crystals with anomalous parity-time symmetry. Remarkably, we rigorously prove that the penetration depth of the edge states is inversely proportional to the frequency and the real part of the chirality. Our findings pave a way towards exploring novel non-Hermitian phenomena and applications in continuous Maxwell's equations.
"Non-Hermitian Skin Effect and Delocalized Edge States in Photonic Crystals with Anomalous Parity-Time Symmetry," Progress In Electromagnetics Research,
Vol. 172, 33-40, 2021. doi:10.2528/PIER21111602
1. Wang, K., A. Dutt, K. Y. Yang, C. C. Wojcik, J. Vučković, and S. Fan, "Generating arbitrary topological windings of a non-Hermitian band," Science, Vol. 371, 1240-1245, 2021. doi:10.1126/science.abf6568
2. Xiao, L., T. Deng, K. Wang, G. Zhu, Z. Wang, W. Yi, and P. Xue, "Non-Hermitian bulk-boundary correspondence in quantum dynamics," Nature Physics, Vol. 16, 761-766, 2020. doi:10.1038/s41567-020-0836-6
3. Helbig, T., T. Hofmann, S. Imhof, M. Abdelghany, T. Kiessling, L. Molenkamp, C. Lee, A. Szameit, M. Greiter, and R. Thomale, "Generalized bulk-boundary correspondence in non-Hermitian topolectrical circuits," Nat. Phys., Vol. 16, 747-750, 2020. doi:10.1038/s41567-020-0922-9
9. Deng, K. and B. Flebus, "Non-Hermitian skin effect in magnetic systems,", arXiv:2109.01711, 2021.
10. Braghini, D., L. G. G. Villani, M. I. N. Rosa, and J. R. de F Arruda, "Non-Hermitian elastic waveguides with piezoelectric feedback actuation: Non-reciprocal bands and skin modes," J. Phys. D: Appl. Phys., Vol. 54, 285302, 2021. doi:10.1088/1361-6463/abf9d9
11. Song, Y., W. Liu, L. Zheng, Y. Zhang, B. Wang, and P. Lu, "Two-dimensional non-Hermitian skin effect in a synthetic photonic lattice," Phys. Rev. Applied, Vol. 14, 064076, 2020. doi:10.1103/PhysRevApplied.14.064076