Reducing dissipation for superconducting qubits*

Extending qubit lifetimes (T₁, T₂) remains a core challenge in developing large-scale quantum computers with superconductors. In this talk, we discuss a variety of substrate cleaning and subtractive patterning techniques responsible for increasing T₁ for superconducting qubits. For these analyses, we have developed fabrication flows based on subtractively-patterned niobium that yield resonators with average internal quality factors of Q_int ≈ 1×10⁶ across several wafers and chips. We show options for integrating Josephson junctions into these process flows to make functional qubits with high coherence times.