Coherent control and shift of exceptional points in micro-ring resonators via resonant frequency through four-level N-type atomic medium

Coherent control of exceptional points (EPs) through resonant frequency manipulation is a pressing question in the field of non-Hermitian physics. EPs, distinguished by the coalescence of eigenvectors and eigenvalues, possess unusual properties that can be a basis for various applications, including sensitivity enhancement, energy harvesting, and signal processing. The current article explores coherent control, with a focus on the resonant frequency as a key parameter. Resonant frequency plays a significant role in the behavior of EPs. It is possible to control their properties and coherent behavior by adjusting the system’s physical parameters, such as the index of refraction, size of the micro-ring resonators, and material properties, to match the desired resonant frequency. Through this control mechanism, it is possible to tailor the transmission and reflection properties of waves, enhancing or suppressing certain modes, and to modify the sensitivity of the system to external perturbations. The present work may enable us to design novel devices for optical communication, sensing, and signal processing, and it may open possibilities for controlling entanglement and coherence in quantum information processing.