Piezoelectric Tunable Microwave Superconducting Cavity

TL;DR

This paper presents a superconducting microwave cavity with tunable high Q-factors, achieved through a piezoelectric actuator, enabling precise frequency control over a large range suitable for quantum systems.

Contribution

The work introduces a 3D reentrant cavity with a piezoelectric tuning mechanism for high-Q superconducting microwave resonators, demonstrating large dynamic range and room/dilution refrigerator operation.

Findings

Achieved up to 4 GHz tuning range at room temperature.

Demonstrated stable operation with high Q-factors.

Observed nonlinear thermal effects at high power levels.

Abstract

In the context of engineered quantum systems, there is a demand for superconducting tunable devices able to operate with high Q-factors at power levels equivalent to only a few photons. In this work, we developed a 3D microwave reentrant cavity with such characteristics ready to provide a very fine-tuning of a high-Q resonant mode over a large dynamic range. This system has an electronic tuning mechanism based on a mechanically amplified piezoelectric actuator, which controls the resonator dominant mode frequency by changing the cavity narrow gap by very small displacements. Experiments were conducted at room and dilution refrigerator temperatures showing a large dynamic range up to 4 GHz and 1 GHz, respectively, and were compared to a FEM model simulated data. At elevated microwave power input, nonlinear thermal effects were observed to destroy the superconductivity of the cavity due to the large electric fields generated in the small gap of the reentrant cavity.