Parameter estimation of non-Hermitian coupling strength in whispering-gallery-mode microresonator

We theoretically propose a scheme to perform quantum estimation of non-Hermitian coupling strength in a whispering-gallery-mode microresonator setup, the estimation precision is quantified through the quantum Fisher information. We systematically studied the impact of various important physical factors on estimation error, and discussed in detail the underlying physical mechanisms. We also explore the distribution of coupling parameter information in various subsystems, while considering the simultaneous estimation of the real and imaginary parts of non-Hermitian coupling parameter. We hope that this work will contribute to the understanding of non-Hermitian interactions and the design of quantum sensors based on whispering-gallery-mode microresonator systems.