Formal Green's function theory in non-Hermitian lattice systems

Abstract: In this paper, we employ the generalized Bloch theory to rediscover the generalized Brillouin zone theory and follow this way to obtain the Green's function of the non-Hermitian system. We focus on a classical chiral model and give the exact expression of the Green's function for a finite-size system and the formal expression of the Green's function suitable for infinite size. Based on these results, we further derive the correlation matrix and validate it numerically against direct calculations for a system of size 40. The numerical results show the accuracy of our exact expression and the high fidelity of our formal expression.