Circuit Electromechanics with a Non-Metallized Nanobeam

We have realized a nano-electromechanical hybrid system consisting of a silicon nitride beam dielectrically coupled to a superconducting microwave resonator. We characterize the sample by making use of the Duffing nonlinearity of the strongly driven beam. In particular, we calibrate the amplitude spectrum of the mechanical motion and determine the electromechanical vacuum coupling. A high quality factor of 480,000 at a resonance frequency of 14 MHz is achieved at 0.5 K. The experimentally determined electromechanical vacuum coupling of 11.5 mHz is quantitatively compared with finite element based model calculations. In the field of cavity optomechanics, micro- or nanoscale mechanical resonators are coupled to an optical cavity allowing to transfer information from the mechani-cal to the optical domain and vice versa1–6. For example, such optomechanical systems have recently been used to observe interference effects like optomechanically induced transparency8 or to cool mechanical resonators to their ground state7. Moreover, they have been e. g. proposed for quantum information processing9 or for the detectio