Toward a multiscale process and device simulation platform for superconducting circuits

Technology computer-aided design (TCAD) is well established in the process of creating, optimizing, and verifying classical circuit designs prior to fabrication, with tools available for modeling behavior at different scales. However, many advancements are still necessary for TCAD of superconducting circuits to match the streamlined multi-scale simulation capabilities of traditional TCAD.

Progress has been made in adapting microwave engineering tools to superconducting circuit modeling needs at the μm or mm scale of the largest components, such as capacitances, resonators, and inductors. However, Josephson junction (JJ) physics is determined at the atomic (Å) scale, motivating the need for realistic atomistic simulations of JJ growth and transmission.

In this talk, we will present simulations of quantum circuit components at both mm and Å scales. To enable the former, we have developed efficient capacitance and resonance mode extraction tools with adaptive meshing. At the atomic scale, we will show how molecular dynamics simulations combining density functional theory (DFT) with artificial intelligence can model key features of the JJ growth process. The resulting atomic structures will then be used as inputs in Non-Equilibrium Green Function DFT (NEGF-DFT) simulations to calculate Josephson energy from first principles. These results contribute to bridging the gap between the multi-scale modeling needs for superconducting circuits and available simulation capabilities.