Fig. 2: Different EP analytical approaches and corresponding theoretical models.
From: Resonant and scattering exceptional points in non-Hermitian metasurfaces
a Schematic diagram of a variation of Hamiltonian eigenvalues with coupling strength. When both the real and imaginary part of eigenvalues degenerates, the system is at EP, which is represented by the orange dot in the figure. b Theoretical models of the resonant EP and the scattering EP, and the general expressions for the corresponding physical quantities, are given under the model. \({\omega }_{i}\), \({\gamma }_{i}\) is the eigenfrequency and loss of the i-th mode, and \({\mu }_{{ij}}\) is the coupling coefficient from the i-th mode to the j-th mode.
