A tunable coupler for suppressing ZZ crosstalk and realizing multiform two qubit-gates

Controllable interaction between superconducting qubits is desirable for scalability architectures and quantum simulation applications. We experimentally demonstrate a simple-design tunable coupler, achieving a continuous tunability and almost zero coupling strength. Based on the tunable interaction between two qubits via the coupler, we first construct two-qubit iSWAP and control-Z(CZ) gate by applying standard rectangular pulses. We then propose a new ‘Dynamic-Total-Closing’(DTC) technology to implement the CZ gate, which adopts a graded flux pulse for the qubit to approach the avoided crossing slowly, meanwhile dynamically closing the qubit-qubit coupling with a special pulse shape during the approaching process(fidelity up to 98.4%). Furthermore, we also try iSWAP gate by parametrically oscillating coupler at the qubit-qubit detuning and cross-resonance gate by tuning coupler frequency to explore the influence of ZZ interaction.