Hybrid magnon-photon system for sensing weak phase

It belongs to a hot topic to sense or detect the weak and even ultra-weak physical quantities by utilizing quantum platforms and methods. We here propose a hybrid magnon-photon system of the yttrium iron garnet (YIG) magnon mode coupled to a microwave cavity, which also includes another degree of freedom with respect to the thermal vibration of this YIG microsphere. In this quasi-tripartite coupling system, we generalize the condition for satisfying energy degeneracy and anti-crossing behaviors. Especially around the zero-energy area, we can get the joint quantum effects of anti-crossing behavior and degeneracy of systemic energy, and then reach a significantly enhanced sensitivity to this phase disturbance. Therefore our proposal can characterize this weak vibration through a phase disturbance and indicate a group of clearly resolvable output spectra. This investigation may be considered as an encouraging attempt on sensing weak quantity by engineering the systemic energy into the critical area for further enlarging its sensitivity to the weak disturbance.