High-quality two-qubit gate operations are crucial for scalable quantum information processing. Often, the gate fidelity is compromised when the system becomes more integrated. Therefore, a low-error-rate, easy-to-scale two-qubit gate scheme is highly desirable. Here, we experimentally demonstrate a new two-qubit gate scheme that exploits fixed-frequency qubits and a tunable coupler in a superconducting quantum circuit. The scheme requires less control lines, reduces cross talk effect, and simplifies calibration procedures, yet produces a controlled-Z gate in 30 ns with a high fidelity of 99.5%, derived from the interleaved randomized benchmarking method. Error analysis shows that gate errors are mostly coherence limited. Our demonstration paves the way for large-scale implementation of high-fidelity quantum operations.
Dr. Yuan Xu got his Ph. D degree at Tsinghua University in 2019 and then joined Shenzhen Institute for Quantum Science and Engineering of Southern University of Science and Technology as an assistant researcher. His research interest includes high-fidelity quantum gates, robust geometric quantum operations, quantum optics and bosonic quantum error correction with superconducting quantum circuits.