Superconducting membrane mechanical oscillator based on vacuum-gap capacitor**Project supported by the National Key Research and Development Program of China (Grant No. 2016YFA0301801), the National Natural Science Foundation of China (Grant Nos. 11474154 and 61521001), and the Priority Academic Development Program of Jiangsu Higher Education Institutions and Dengfeng Project B of Nanjing University, China.

Abstract

Using the diluted S1813 UV photoresist as a sacrificial layer, we successfully fabricate a superconducting suspended parallel-plate capacitor, in which the top layer of aluminum film acts as a membrane mechanical resonator. Together with a superconducting octagonal spiral inductor, this parallel-plate capacitor constitutes a superconducting microwave resonator. At mK temperature, the transmission characteristic and spectrum of the microwave resonator are measured. Sideband frequencies caused by the vibration of the membrane mechanical resonator are clearly demonstrated. By down-converting with a mixer, the dependence of fundamental frequency and its harmonics on the input microwave power are clearly demonstrated, which is consistent with the numerical simulation.