Floquet higher-order exceptional points and dynamics in PT-symmetric quadrimer waveguides Jun Jia, Bo Zhu, Fuqiu Ye, Honghua Zhong and Haiming Deng Eur. Phys. J. D, 74 6 (2020) 117 Published online: 16 June 2020 DOI: 10.1140/epjd/e2020-10021-0