Comparative Analysis of Qubit-Package Coupling Extraction Techniques

Accurate prediction of the coupling strength between superconducting qubits and electromagnetic modes of their enclosing package is critical for high-fidelity quantum hardware design. We present a systematic comparison and benchmarking of four new, as well as existing methods of electromagnetic (EM) modeling techniques for extracting the coupling parameter. These methods are:  Avoided Level Crossing, Energy Participation Ratio (EPR), LC-Circuit Fitting, and the Induced Voltage Calculation.

Our work examines the relative strengths and weaknesses of each method, particularly concerning internal circuit parasitics, and simulation computational cost. We demonstrate that the LC-Circuit Fitting method yields an effective circuit, including internal inductances often neglected by simpler models. The comparison is applied to a common hardware architecture, and aims to establish a set of best practices for the EM modeling community to ensure reliable and efficient design of quantum processing units.