Structure and Formation Mechanisms in Tantalum and Niobium Oxides in Superconducting Quantum Circuits.

Improving the qubit's lifetime (T) is crucial for fault-tolerant quantum computing. Recent advancements have shown that replacing niobium (Nb) with tantalum (Ta) as the base metal significantly increases T, likely due to a less lossy native surface oxide. However, understanding the formation mechanism and nature of both surface oxides is still limited.