Surface acoustic wave resonators on thin film piezoelectric substrates in the quantum regime

Lithium niobate (LNO) is a well established material for surface acoustic wave (SAW) devices including resonators, delay lines and filters. Recently, multi-layer substrates based on LNO thin films have become commercially available. Here, we present systematic low-temperature study of the performance SAW fabricated LNO-on-insulator LNO-on-Silicon compare them to bulk devices. Our aims at assessing these quantum acoustics, i.e. integration with superconducting circuits operating in regime. To this end, design resonators target frequency 5 GHz perform experiments millikelvin temperatures microwave power levels corresponding single photons or phonons. The are investigated regarding their internal quality factors as function excitation temperature, which allows us characterize quantify losses identify dominating loss mechanism. For measured devices, fitting experimental data shows that limited by coupling resonator bath two-level-systems. results suggest film silicon comparable viable use SAW-based