Multi-qubits entanglement in a single step with global parametric gate

Quantum entanglement is a hallmark of quantum systems, distinguishing them from classical ones. However, preparing large-scale multi-qubit entangled states remains challenging, as it requires complete control over the qubits and their noise environment. Exploiting global quantum gates that generate multi-qubit entanglement in a single-step would help reduce quantum circuit depth and improve simulation efficiency. In this work, we demonstrate a global entangling gate in a superconducting processor with a high-connectivity architecture, using a bus resonator for programmable inter-qubit coupling. By parametrically driving on a common qubit with precise frequency detunings relative to the computational qubits, we generate a four-qubit entangled state in a single step with a fidelity of 91.69%.

Our gate implementation differs from conventional parametric approaches, which either use a microwave-driven tunable coupler for two-qubit gates or generate multi-qubit states by sequentially applying two-qubit gates to qubit pairs. This unique global gate scheme excels at producing multi-qubit entanglement efficiently, offering reconfigurable control solely through parametric microwave drives. The method enables the use of fixed-frequency computational qubits, providing frequency selectivity while alleviating frequency crowding and minimizing sensitivity to environmental noise.