Energy-participation approach to the design of quantum Josephson circuits

Superconducting circuits incorporating non-linear devices, such as Josephson tunnel junctions and nanowires, are among the leading platforms for emerging quantum technologies. Promising applications require designing and optimizing circuits with ever-increasing complexity and controlling their dissipative and Hamiltonian parameters to several significant digits. Therefore, there is a growing need for a systematic, simple, and robust approach for precise circuit design, extensible to increased complexity. In this talk, we present such an approach to unify the design of dissipation and Hamiltonians around a single concept — the energy participation, a number between zero and one — in a single-step electromagnetic simulation. This markedly reduces the required number of simulations and allows for robust extension to complex systems. The approach is general purpose, valid for arbitrary non-linear devices and circuit architectures. We present experimental results on a variety of circuit quantum electrodynamics (cQED) devices and architectures, 3D and flip-chip (2.5D), which exhibit percent-level agreement for Hamiltonian parameters over five-orders of magnitude and across a dozen devices.