Quantum sensing with optomechanical systems

We discuss a hybrid optoelectromechanical setup that is able to sense weak variations of any parameter that affects the effective capacitance of an LC resonator, representing the radiofrequency (rf) electrical component of the device. In the setup, either one or two mechanical modes mediate the interaction between an optical cavity and the rf-resonator. This system can be operated in a regime of impedance matching where thermal fluctuations are redistributed among the system elements, and, in particular, rf output noise can be reduced to the quantum vacuum noise level. We show that this effect can boost the sensitivity in detecting parameter variations also in regimes of high thermal noise.