Integrating superconducting circuits with phononic bandgap structures for quantum networking and memory

Superconducting quantum processors have become highly developed noisy intermediate-scale quantum systems, yet many challenges remain to fully developing their quantum information processing capabilities such as developing long distance quantum coherent transmission and memory. Coupling these circuits directly to phononic modes provides a path to addressing these challenges. Phononic modes of dielectric bandgap crystals can have lifetimes of order seconds, far exceeding superconducting coherence times. Moreover, phononic modes can be frequency matched to superconducting circuits and wavelength matched to optical modes, providing a path for quantum networking via an optical channel. Here, we present our progress developing superconducting circuits for integration with phononic bandgap crystals. We investigate multiple dielectric platforms including circuits fabricated on silicon-on-oxide (SOI) substrates, as phononic bandgap devices have been extensively developed on SOI.