Abstract
With recent advances in state preparation, gate, and measurement operations, superconducting circuit architectures are now leading candidates for quantum information processing. As micro-fabricated circuits are scaled up towards a practical quantum processor, strict requirements on the fidelity of operations required for quantum computation are imposed. For theorists, this mandates the development of accurate models describing the dynamics of complex superconducting circuits subject to strong drives.

This talk will begin with an elementary introduction to such systems and their description in terms of quantum electrodynamics, the fundamental theory of light-matter interactions. We will then address the problem of the Purcell effect, which is the enhancement of the decay rate of a single qubit due to a linear electromagnetic environment, and show how convergent results can be obtained without any artificial high-frequency cutoffs. We will also explain how the Purcell rate is further enhanced in the presence of the drive fields typically used to measure qubits, which is a ubiquitous problem encountered in present-day experiments.