  Non-Hermitian skin effect denotes the exponential localization of a large
number of eigen-states 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.
