2025/03/28 by Joshoua Condicion Esmenda, E. A. Laird, Esmenda, J. C. +17
Physics and Astronomy · #Advanced Frequency and Time Standards #Atomic and Subatomic Physics Research #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #Superconductivity (cond-mat.supr-con)
paper · pdf · doi:10.48550/arxiv.2503.22637
openalex publication_date 2025/03/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Superconducting microwave cavities have found applications in many areas including quantum computing, particle accelerators, and dark matter searches. Their extremely high quality factors translate to very narrow bandwidth, which makes them key components of sensitive detectors. In this study, we aim to understand the loss mechanisms of an aluminium cavity and how they change as the cavity material transitions from the superconducting to normal state. We found that at temperatures not much lower than the transition temperature Tc, losses are dominated by quasiparticle excitations and are well described by the BCS theory. The exponential decrease of the quasiparticle density below Tc results in a 1000-fold increase of the quality factor, as well as a shift of the resonance frequency due to the change of the kinetic inductance of the superconductor. At very low temperatures, losses due to two-level systems begin to dominate giving a peak in the quality factor of about 27.6 million at 130 mK. Understanding the loss mechanisms is invaluable, as the working temperature of the cavity may vary during operation regardless of its application.