Noise and loss from the dielectric environment of planar superconducting circuits

Understanding of loss mechanisms in superconducting resonators has helped to produce long-lived superconducting qubits. Most notably, for identical fabrication processes, the single-photon quality factor has become a reliable indicator for qubit relaxation time. While this understanding of loss has seen typical T₁ approach ≈100μs, the dephasing times often remain far below the relaxation limit. Superconducting resonators can provide information on the time-varying properties of these decoherence mechanisms. We show measurements on a variety of superconducting resonators and qubits, showing that our mean qubit T₁ (75μs) is consistent with our mean resonator single photon Q_i (10⁶). We then study the temporal properties of the resonator in the framework of interacting two-level systems and apply this understanding to fluctuations in qubit parameters.