Feedback and PT symmetry in a class of active LCR circuits

Systems with non-Hermitian Hamiltonians, especially those exhibiting parity-time (PT) symmetry, are of particular interest as they can describe physical open systems with balanced loss into and gain from the environment. In this context, the study of eigenvalue locations and the corresponding phase transi-tions as a function of the degree of non-Hermiticity are accomplished hereby using feedback theory. This approach provides insight about the behavior of these systems and allows generalization of the results for higher-order ones. The proposed ideas are analyzed in detail for a class of coupled resonant circuit chains.