With the continued scaling of superconducting circuits for high-speed adiabatic logic and quantum gates, operating frequency demands on quantum devices will inevitably approach speeds nearing 1 THz [1]. Large scale on-chip device connectivity additionally requires long range, lossless, and phase coherent inter-chip cabling and 3D heterogeneous chiplet integration [2]. However, existing state-of-the-art predictive methods center on cQED-based Hamiltonian engineering and 3D EM modeling reliant on conversion of superconducting layers to perfect electrical conductor (PEC) sheets [3]. Superconducting transmission lines modeled with PEC do not support EM propagation beyond TEM modes or capture realistic quasiparticle behavior [4]. Here, we discuss multiscale device modeling techniques that incorporate realistic effects driven by EM fields in bulk material. Simulations from bulk reveal RF scaling limitations not predicted by the current state-of-the-art.

[1] W. Chen, et al. Rapid single flux quantum T-flip flop operating up to 770 GHz. IEEE Trans. Appl. Supercon. 9, 3212 (1999).

[2] S. Bravyi, et al., The future of quantum computing with superconducting qubits. J. Appl. Phys. 132, 160902 (2022).

[3] S. H. Park, et al. Kinetic-inductance-incorporated quantization for accurate Hamiltonian prediction in superconducting circuits. npj Quantum Inf. 12, 58 (2026).