Loss analysis of curved surface acoustic wave resonators for circuit quantum acoustic systems*

Acoustic systems are a promising platform for building compact resonators that interact with superconducting qubits. Central to this goal is increasing the quality factor Q of surface acoustic wave (SAW) resonators.  This necessitates the detailed characterization of the dominant loss mechanisms.  Here, we analyze 500 MHz SAW resonators on ST-X cut quartz with curved geometry, considering the anisotropy of the substrate.  We investigate the loss mechanisms and mode structure of these curved resonators. We describe schemes for mitigating these losses, providing a path for realizing SAW resonators with Q approaching one million.