Microwave

Quantum mechanics

Engineering

Dielectric loss

Materials science

Telecommunications

Scalability

Computer science

Electronic circuit

Josephson effect

Physics

Nanotechnology

Database

Dielectric

Superconductivity

Superconducting coherence length

Electronic engineering

Resonator

Condensed matter physics

Quantum

Qubit

Optoelectronics

Superconducting quantum computing

Electrical engineering

Engineering physics

Review of Scientific Instruments

The performance of superconducting circuits for quantum computing is limited by materials losses. In particular, coherence times are typically bounded by two-level system (TLS) losses at single photon powers and millikelvin temperatures. The identification of low loss fabrication techniques, materials, and thin film dielectrics is critical to achieving scalable architectures for superconducting quantum computing. Superconducting microwave resonators provide a convenient qubit proxy for assessing performance and studying TLS loss and other mechanisms relevant to superconducting circuits such as non-equilibrium quasiparticles and magnetic flux vortices. In this review article, we provide an overview of considerations for designing accurate resonator experiments to characterize loss, including applicable types of loss, cryogenic setup, device design, and methods for extracting material and interface losses, summarizing techniques that have been evolving for over two decades. Results from measurements of a wide variety of materials and processes are also summarized. Lastly, we present recommendations for the reporting of loss data from superconducting microwave resonators to facilitate materials comparisons across the field.

Materials loss measurements using superconducting microwave resonators