Versatile parametric coupling between two statically decoupled transmon qubits

Parametric coupling is a powerful technique for generating tunable interactions between superconducting circuits using only microwave tones. Here, we present a highly flexible parametric coupling scheme demonstrated with two transmon qubits, which can be employed for multiple purposes, including the removal of residual ZZ coupling and the implementation of driven swap or swap-free controlled-Z (cZ) gates. Our fully integrated coupler design is only weakly flux tunable, cancels static linear coupling between the qubits, avoids internal coupler dynamics or excitations, and operates with rf-pulses. We show that residual ZZ coupling can be reduced with a parametric dispersive tone down to an experimental uncertainty of 5.5 kHz. Additionally, randomized benchmarking reveals that the parametric swap cZ gate achieves a fidelity of 99.4% in a gate duration of 60 ns, while the dispersive parametric swap-free cZ gate attains a fidelity of 99.5% in only 30 ns. We believe this is the fastest and highest fidelity gate achieved with on-chip parametric coupling to date. We further explore the dependence of gate fidelity on gate duration for both p-swap and p-swap-free cZ gates, providing insights into the possible error sources for these gates. Overall, our findings demonstrate a versatility, precision, speed, and high performance not seen in previous parametric approaches. Finally, our design opens up new possibilities for creating larger, modular systems of superconducting qubits.