Designing Better Superconducting Qubits using First-Principles Calculations and Theory

Superconducting qubits have emerged as one of the leading candidates for scalable quantum computing, despite suboptimal coherence times and resonantor quality factors. In this work, we combine first-principles calculations and effective models to describe key performance losses in niobium-based superconducting qubits. We find that defects play a decisive role in their operational efficiency, and that careful control of stoichiometry can significantly improve their performance. We compare our theoretical predictions with recent experiments confirming the importance for defects for understanding decoherence pathways in qubits and quantum materials.