arbitrary-order exceptional points of quasistationary states based on the permutation group.
Our studies reveal all possible product permutations of holonomy matrices that describe a
stroboscopic encircling of second-order exceptional points. The permutations turn out to be
categorized into a finite number of classes according to the topological structures of the
Riemann surfaces. Our results are verified by an effective non-Hermitian Hamiltonian …