Quantifying Losses in Transmon Qubits*

Reducing losses in superconducting qubit circuits is critical for enabling the development of large-scale quantum computing architectures. This task is especially challenging in the face of variability resulting from device-to-device differences and fluctuating device properties. We apply statistical characterization of sets of superconducting resonators and transmon qubits to overcome variability and quantify loss contributions from a variety of sources such as surface and bulk dielectrics, packaging, and nonequilibrium quasiparticles. As part of this approach, we develop the fabrication processes and EM modeling techniques necessary for accurately modeling dielectric losses. Through this study, we seek to develop a model of qubit losses that allows for iterative improvement in device coherences and consistency.