Planarized Millimeter Wave Optomechanical Circuits

Vacuum gap capacitors have been a fruitful platform for microwave optomechanics for over a decade. As with all quantum optomechanics platforms, there is a strong desire to reduce the dissipation of both the mechanical and electromagnetic modes while also increasing the coupling strength between them. Such advances could enable novel regimes of quantum optomechanics which would go beyond Gaussian states and operations. Recent work has shown that device planarization techniques can significantly reduce mechanical dissipation in such devices. Parallel work has also shown that increasing the cavity frequency from the microwave to the millimeter wave regime markedly improves both the vacuum and parametric optomechanical coupling rates. Here, we attempt to incorporate both advances into a single device. We will present experimental progress in fabrication and characterization of these devices.