Materials loss measurements using superconducting microwave resonators.

Area of Science:

• Quantum Computing
• Materials Science
• Superconducting Circuits

Background:

• Superconducting circuit performance is hindered by material losses, especially two-level system (TLS) losses at low temperatures and photon powers.
• Scalable quantum computing architectures necessitate the identification of low-loss fabrication techniques, materials, and thin-film dielectrics.

Purpose of the Study:

• To provide an overview of designing accurate resonator experiments for characterizing material and interface losses in superconducting circuits.
• To summarize techniques for assessing performance and studying loss mechanisms relevant to superconducting quantum computing.

Main Methods:

• Utilizing superconducting microwave resonators as qubit proxies to study loss mechanisms.
• Reviewing experimental considerations including cryogenic setup, device design, and loss extraction methods.
• Summarizing over two decades of evolving techniques for materials characterization.

Main Results:

• Results from measurements across a variety of materials and processes are compiled.
• Identified key factors influencing loss, including TLS, non-equilibrium quasiparticles, and magnetic flux vortices.
• Highlighted the importance of accurate loss characterization for material selection.

Conclusions:

• Accurate resonator experiments are critical for understanding and mitigating losses in superconducting quantum computing.
• Standardized reporting of loss data is recommended to facilitate cross-field material comparisons.
• Advancing low-loss materials and fabrication is essential for scalable quantum architectures.