Experimental Realization of a Fast Controlled-Z Gate via a Shortcut to Adiabaticity

For a frequency-tunable two-qubit system, a controlled-Z (cz) gate can be realized by adiabatic driving of the qubit system through an avoided level crossing between an auxiliary state and computational levels. Here we theoretically propose a fast cz gate using a shortcut to adiabaticity (STA). Experimentally, the STA cz gate is implemented with a 52-ns control pulse for two coupled superconducting Xmon qubits. The measured fidelity of the STA cz gate is higher than 96.0% in both quantum-process tomography and randomized benchmarking. The protocol allows a flexible design of the evolution time and control waveform. We suggest that this fast adiabatic cz gate can be directly applied to other multiqubit quantum systems.