Analytical flux-tuned iSWAP pulse suppressing excitations in qubits and coupler

Achieving fast, high-fidelity qubit gates remains one of the major challenges in quantum computing, and despite recent progress, enhancing the efficiency of superconducting two-qubit gates still presents complications. In this work we investigate optimal control methods in order to improve the fidelity of two qubit gates in a flux tunable architecture based on a tunable coupler. We emphasize the importance of suppression of various leakage channels and we demonstrate simulations with optimal control methods (DRAG) on the external flux on the tunable coupler, achieving further improved fidelities for an iSWAP gate. Finally, we propose a generalized pulse-shaping approach for the external flux, leading to significant leakage suppression across different circuit parameters.