Quantum Parameter Estimation of Optomagnonic Coupling

ABSTRACT

Optomagnonic interactions bridge microwave‐frequency magnons and optical‐frequency photons and are important for hybrid quantum technologies. Precise calibration of the optomagnonic coupling strength is therefore essential, especially in the weak‐coupling regime. We propose a high‐precision estimation scheme for hertz‐to‐kilohertz optomagnonic coupling strengths based on homodyne detection of measurable output temporal modes under realistic experimental constraints. Using quantum Fisher information (QFI), we identify optimal operating regimes and show that joint local optical homodyne detection can nearly saturate the intracavity QFI over a broad parameter range. By constructing finite‐duration output temporal modes, we further demonstrate that the Fisher information can be efficiently extracted from accessible optical outputs. Finally, numerical simulations of the measurement process verify the estimation workflow and its robustness against parameter uncertainties.