Engineering high-Q surface acoustic wave (SAW) resonators for superconducting circuits, Part 1

Mechanical resonators are promising bosonic quantum memories for circuit-QED, featuring small footprints and excellent integration compatibility. However, the state-of-the-art resonators often face a trade-off between large coupling strengths (g) and high mechanical quality factors (Q). In addition, unless carefully engineered, quantum acoustic systems typically exhibit spurious modes which might cause unwanted interactions with superconducting circuits. In the first part of the talk, we present a high Q surface acoustic wave resonator that maximizes the coupling rate to superconducting circuit elements. We accomplish this by engineering the mirror bandgap and suppressing radiation into the bulk acoustic continuum from mechanical junctions, which is a dominant source of decoherence in SAW devices. These results pave the way for robust integration of SAW resonators with superconducting quantum circuits.