Document Type
Article
Publication Date
2025
DOI
10.1063/5.0282159
Publication Title
Applied Physics Letters
Volume
127
Issue
15
Pages
152601
Abstract
Trapped magnetic vortices in niobium introduce microwave losses that degrade the performance of superconducting resonators. While such losses have been extensively studied above 1 K, we report here their direct quantification in the millikelvin and low-photon regime relevant to quantum devices. Using a high-quality factor 3D niobium cavity cooled through its superconducting transition in controlled magnetic fields, we isolate vortex-induced losses and find the resistive component of the sensitivity to trapped flux S to be approximately 2 n Ω/mG at 10 mK and 6 GHz. The decay rate is initially dominated by two-level system (TLS) losses from the native niobium pentoxide, with vortex-induced degradation of T₁ occurring above Btrap ∼ 50 mG. In the absence of the oxide, even 10 mG of trapped flux limits performance, Q₀ ∼ 10¹⁰, or T₁ ∼ 350 ms, underscoring the need for stringent magnetic shielding. The resistive sensitivity, S, decreases with temperature and remains largely field-independent, whereas the reactive component, S′, exhibits a maximum near 0.8 K. These behaviors are well modeled within the Coffey-Clem framework in the zero-creep limit, under the assumption that vortex pinning is enhanced by thermally activated processes. Our results suggest that niobium-based transmon qubits can tolerate vortex-induced dissipation at trapped field levels up to several hundred mG, but achieving long coherence times still requires careful magnetic shielding to suppress lower-field losses from other mechanisms.
Rights
© 2025 Authors.
This work is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) License.
Data Availability
Article states: "The data that support the findings of this study are available from the corresponding author upon reasonable request."
Original Publication Citation
Bafia, D., Abdisatarov, B., Pilipenko, R., Lu, Y., Eremeev, G., Romanenko, A., & Grassellino, A. (2025). Quantifying trapped magnetic vortex losses in niobium resonators at mK temperatures. Applied Physics Letters, 127(15), Article 152601. https://doi.org/10.1063/5.0282159
Repository Citation
Bafia, D.; Abdisatarov, B.; Pilipenko, R.; Lu, Y.; Eremeev, G.; Romanenko, A.; and Grassellino, A., "Quantifying Trapped Magnetic Vortex Losses In Niobium Resonators at mK Temperatures" (2025). Electrical & Computer Engineering Faculty Publications. 574.
https://digitalcommons.odu.edu/ece_fac_pubs/574
ORCID
0009-0007-3160-3575 (Abdisatarov)