Speaker
Description
Niobium-based superconducting radio-frequency (SRF) cavities are crucial for particle accelerators, yet their performance is limited by native niobium oxide formation, which contributes significantly to increased residual surface resistance. This oxidation challenge is similarly critical in superconducting quantum circuits, where niobium oxide layers adversely impact coherence times and device stability. To address these issues, we present a first-principles density functional theory (DFT) study exploring surface passivation strategies using noble metals (Au, Pt, Pd) and stable oxide coatings (Al₂O₃, ZrO₂) on Nb substrates. Our calculations systematically assess the thermodynamic stability, interface energies, and electronic interactions at Nb–coating interfaces. Results identify several candidate materials exhibiting superior stability compared to native niobium oxide, potentially suppressing its formation. By effectively passivating the Nb surface, these coatings promise significant reductions in residual resistance for SRF cavities and enhanced coherence for superconducting qubits. These insights offer theoretical guidance for experimental implementation, contributing to improved performance across superconducting technologies.
Funding Agency
This work was supported by the US National Science Foundation under award PHY-1549132, the Center for Bright Beams.
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