Enhanced Sensitivity of Gyrator-based Circuit at Exceptional Point Composed of Unstable Resonators

We show the enhanced sensitivity to perturbations of a circuit comprising two unstable resonators coupled via a gyrator in the vicinity of the exceptional point of degeneracy (EPD) with purely real eigenfrequency. Each resonator includes a negative capacitance, showing purely imaginary resonance frequency when not coupled via the gyrator. When applying an external perturbation to the circuit, we confirm that the eigenfrequencies of the circuit follow the typical second-order EPD square-root dependence on perturbation, leading to possible sensor applications. We analyze the effect of losses in the resonators that lead to instability. The very high sensitivity induced by an EPD paves the way to realize a new generation of high-sensitive sensors to measure small physical or chemical perturbations.