Time-domain electromagnetic modeling for multi-qubit superconducting systems

Superconducting quantum processors remain limited by inter-qubit and interconnect crosstalk, which constrains system scalability and gate performance. In this work we developed and utilized an HPC driven finite-difference time-domain (FDTD) EM solver to accurately model the transient crosstalk behavior in an 8-qubit superconducting quantum processor. We can capture the temporal evolution of EM fields across qubit, control, and readout structures, enabling direct comparison between simulated coupling waveforms and experimental measurements with fidelity and scalability that surpass traditional frequency domain solvers. This time-domain EM modeling enables crosstalk prediction and system-level design optimization for scalable superconducting quantum hardware, providing a pathway for future mitigation and calibration strategies.