Surface acoustic wave resonators in the quantum regime

TL;DR

This study systematically measures the quality factors of surface acoustic wave resonators at millikelvin temperatures, demonstrating high Q-factors up to several gigahertz, and explores their potential for quantum circuit integration.

Contribution

The paper provides the first comprehensive analysis of SAW resonator quality factors at cryogenic temperatures and high frequencies, highlighting their suitability for quantum technologies.

Findings

Q_i approaches 0.5 million at 0.5 GHz

Q_i remains above 4.0×10^4 up to 4.4 GHz

Propagation loss depends polynomially on frequency

Abstract

We present systematic measurements of the quality factors of surface acoustic wave (SAW) resonators on ST-X quartz in the gigahertz range at a temperature of $10 \, \textrm{mK}$. We demonstrate a internal quality factor $Q_\mathrm{i}$ approaching $0.5$ million at $0.5 \, \textrm{GHz}$ and show that $Q_\mathrm{i}\geq4.0\times10^4$ is achievable up to $4.4 \, \textrm{GHz}$. We show evidence for a polynomial dependence of propagation loss on frequency, as well as a weak drive power dependence of $Q_\mathrm{i}$ that saturates at low power, the latter being consistent with coupling to a bath of two-level systems. Our results indicate that SAW resonators are promising devices for integration with superconducting quantum circuits.