Characterizing microwave losses in superconducting quantum circuits: Part 2*

The performance of superconducting quantum circuits has advanced tremendously in the past two decades, with coherence times increasing by over six orders of magnitude. In the past, improvements have been made by modifying circuit geometry; recently, improvements have been achieved through advancements in materials and processing. As coherence times continue to rise, it is becoming less apparent which loss mechanisms dominate the total internal loss of transmon qubits and microwave resonators. In this talk, we will demonstrate the power of loss characterization by using multimode stripline resonators to predict and verify the decay times of transmon qubits, and calculate their sensitivity to various sources of loss. In addition, we will discuss a pathway towards optimizing superconducting circuit design to realize on-chip quantum memories with coherence times approaching one millisecond.