Epitaxially-grown superconductor/dielectric/superconductor trilayers have the potential to form high-performance superconducting quantum devices and may even allow scalable superconducting quantum computing with low-surface-area qubits such as the merged-element transmon. In this work, we measure the power-independent loss and two-level-state (TLS) loss of epitaxial, wafer-bonded, and substrate-removed Al/GaAs/Al trilayers by measuring lumped element superconducting microwave resonators at millikelvin temperatures and down to single photon powers. The power-independent loss of the device is (4.8±0.1)×10−5 and resonator-induced intrinsic TLS loss is (6.4±0.2)×10−5. Dielectric loss extraction is used to determine a lower bound of the intrinsic TLS loss of the trilayer of 7.2×10−5. The unusually high power-independent loss is attributed to GaAs's intrinsic piezoelectricity.
@article{arxiv.2009.10101,
title = {Cryogenic microwave loss in epitaxial Al/GaAs/Al trilayers for superconducting circuits},
author = {C. R. H. McRae and A. McFadden and R. Zhao and H. Wang and J. L. Long and T. Zhao and S. Park and M. Bal and C. J. Palmstrøm and D. P. Pappas},
journal= {arXiv preprint arXiv:2009.10101},
year = {2021}
}