Electrostatic Gate-Tunable Josephson Junctions in JoSIM: Modeling, Simulation, and I–V Characterization

Gate-tunable Josephson junctions (GTJJs) have emerged as promising elements for superconducting electronics and quantum circuits, enabling electric-field control of the Josephson coupling. In this work we present a simulation study of GTJJs using the open-source Josephson circuit simulator JoSIM [1]. We describe how gate control is incorporated into the JJ model in JoSIM via a gate control node and critical current modulation parameter. A dynamic modulation of junction critical current <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$I_{c}$</tex-math></inline-formula> by an applied gate voltage is implemented using a piecewise-linear ramp-off governed by a single width parameter. Using this model, we simulate a gate-tunable superconducting resonator consisting of a Josephson junction in parallel with a capacitor. The resonant frequency is shown to shift as the gate bias alters the junction's effective inductance. We discuss the broader applications of GTJJs in tunable resonators, superconducting logic, parametric amplifiers, and quantum gate devices, as well as practical modeling considerations such as numerical stability. The results demonstrate that JoSIM can effectively capture the behavior of gate-modulated JJs, providing a useful tool for the design of next-generation superconducting circuits that leverage voltage-controlled Josephson elements.