A reproducible design for multi-mode high-Q superconducting quantum electromechanics*

Superconducting electromechanical systems have been among the most successful platforms to study mechanical motion in the quantum regime. These systems are implemented by LC superconducting resonators with a mechanically-compliant capacitor. However, these systems suffer from the low reproducibility of the nanofabrication process, severely limiting their scalability. This restricts the realization of multi-mode electromechanical systems and limits the achievable mechanical quality factors, which largely determine the thermal coherence time.
Here we introduce a reproducible design using a novel nanofabrication process to make a flat high-stress aluminum trampoline resonator. We demonstrate full control of the system's mechanical and microwave properties by making a flat drumhead capacitor. We achieve mechanical quality factors up to 4 million, allowing for similarly longer thermal coherence times.
We believe the new design will open a window to study multi-mode phenomena such as collective behavior and topological physics in optomechanical arrays.