A phase-controlled sensing paradigm in non-Hermitian closed-loop optomechanical system

We theoretically study optomechanical sensing in a non-Hermitian ternary coupled system composed of an optical cavity and two mechanical resonators. The couplings among the cavity and mechanical resonators form a closed-contour interaction accompanied by a Peierls phase. We demonstrate a method for controlling sensitivity through precise manipulation of the closed-loop phase in the system. The sensitivity in measurement can be enhanced for specific values of the global phase. We quantify the system's performance via quantum Cramér–Rao bound highlighting key conditions that optimize measurement precision. Another control parameter is the mechanical coupling constant chosen close to the so-called exceptional point. Overall, the realistic and optimal parameter set enables us to enhance sensitivity and achieve a spectral density close to the standard quantum limit.