Automated Extraction of Superconducting Qubit–Qubit Couplings from Full-Wave Multiport Impedance with Reduced-Model Analysis

Accurate prediction of qubit–qubit exchange coupling is essential for superconducting processor design. We present and benchmark an automated full-wave electromagnetic (EM) workflow in Keysight Advanced Design System (ADS) and QuantumPro that evaluates pairwise exchange couplings from layout-level multiport responses using the established transfer-impedance relation of Solgun et al. Because many scalable superconducting processors employ repeated or near-repeated coupling motifs, reduced EM models can lower computational cost if their error is quantified. We study nearest-neighbor couplings in a reconstructed geometry based on the IBM Q 16 Rueschlikon processor using a sixteen-qubit (16Q) coupling-network model, four-qubit (4Q) unit-cell models, and pair-specific two-qubit (2Q) sub-blocks. The 4Q models provide a like-for-like external benchmark because they match the model extent used by Solgun et al. for the published full-wave coupling calculations. The 4Q models reproduce the published simulated couplings with a 3.70% mean absolute percentage error and differ from 16Q by 3.62% on average. For the representative single solves reported here, the 16Q solve takes approximately 7.2 times as long as 4Q and requires 5.7 times the peak memory. This supports 4Q as a practical reduced model for quantitative local coupling prediction. Further reduction to 2Q changes the couplings by 6.17% on average but remains effective for inexpensive mesh-convergence screening. The resulting workflow provides automated exchange-coupling extraction together with model-extent and convergence assessment in a commercial microwave EDA environment.