A versatile parametric coupler between two transmon qubits

Parametric coupling is a powerful tool that can be used to generate tunable coupling between superconducting qubits via a microwave pump. In this talk, we demonstrate a versatile parametric coupler between two transmon qubits, which can be used to eliminate the residual ZZ coupling between the qubits, to realize a cZ gate by on-resonant parametric coupling, as well as a new kind of cZ gate by off-resonant parametric ZZ manipulation. In the residual ZZ coupling elimination experiment, we show that the upper limit of the effective ZZ coupling after elimination is nominally zero, with an experimental upper limit of 1-10 kHz. Randomized benchmarking experiments show that the on-resonant cZ gate has a fidelity of 99.4% with a gate time of 60 ns, whereas the off-resonant cZ gate has a fidelity of 99.5% with a gate time of 30 ns. We show the gate time dependence of the fidelities of both types of cZ gates and discuss the source of error for those gates.