High-order exceptional points in supersymmetric arrays
S. M. Zhang, X. Z. Zhang, L. Jin, Z. Song
Abstract
We employ the intertwining operator technique to synthesize a supersymmetric (SUSY) array of arbitrary size $N$. The synthesized SUSY system is equivalent to a spin $(N\ensuremath{-}1)/2$ under an effective magnetic field. By considering an additional imaginary magnetic field, we obtain a generalized parity-time-symmetric non-Hermitian Hamiltonian that describes a SUSY array of coupled resonators or waveguides under a gradient gain and loss; all the $N$ energy levels coalesce at an exceptional point (EP), forming an isotropic high-order EP with $N$ states coalescence (EPN). Near the EPN, the scaling exponent of phase rigidity for each eigenstate is $(N\ensuremath{-}1)/2$; the eigenfrequency response to the perturbation $\ensuremath{\epsilon}$ acting on the resonator or waveguide couplings is ${\ensuremath{\epsilon}}^{1/N}$. Our findings reveal the importance of the intertwining operator technique for spectral engineering and exemplify the practical application in non-Hermitian physics.