Document Type

Article

Publication Date

2023

DOI

10.1088/1361-6668/acc214

Publication Title

Superconductor Science and Technology

Volume

36

Issue

6

Pages

063002 (1-29)

Abstract

Performance of superconducting resonators, particularly cavities for particle accelerators and micro cavities and thin film resonators for quantum computations and photon detectors has been improved substantially by recent materials treatments and technological advances. As a result, the niobium cavities have reached the quality factors Q ~ 1011 at 1-2 GHz and 1.5 K and the breakdown radio-frequency (rf) fields H close to the dc superheating eld of the Meissner state. These advances raise the question whether the state-of-the-art cavities are close to the fundamental limits, what these limits actually are, and to what extent the Q and H limits can be pushed by the materials nano structuring and impurity management. These issues are also relevant to many applications using high-Q thin film resonators, including single-photon detectors and quantum circuits. This topical review outlines basic physical mechanisms of the rf nonlinear surface impedance controlled by quasiparticles, dielectric losses and trapped vortices, as well as the dynamic field limit of the Meissner state. Sections cover ways of engineering an optimum quasiparticle density of states and superfluid density to reduce rf losses and kinetic inductance by pairbreaking mechanisms related to magnetic impurities, rf currents, and proximity-coupled metallic layers at the surface. A section focuses on mechanisms of residual surface resistance which dominates rf losses at ultra low temperatures. Microwave losses of trapped vortices and their reduction by optimizing the concentration of impurities and pinning potential are also discussed.

Rights

© 2023 The Author.

Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Data Availability

Article states: "No new data were created or analysed in this study."

Original Publication Citation

Gurevich, A. (2023). Tuning microwave losses in superconducting resonators. Superconductor Science and Technology, 36(6), 1-29, Article 063002. https://doi.org/10.1088/1361-6668/acc214

ORCID

0000-0003-0759-8941 (Gurevich)

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