High-fidelity, high-scalability two-qubit gate scheme for superconducting qubits

  1. Yuan Xu,
  2. Ji Chu,
  3. Jiahao Yuan,
  4. Jiawei Qiu,
  5. Yuxuan Zhou,
  6. Libo Zhang,
  7. Xinsheng Tan,
  8. Yang Yu,
  9. Song Liu,
  10. Jian Li,
  11. Fei Yan,
  12. and Dapeng Yu
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 crosstalk effect, simplifies calibration procedures, yet produces a controlled-Z gate in 30ns with a high fidelity of 99.5%. Error analysis shows that gate errors are mostly coherence-limited. Our demonstration paves the way for large-scale implementation of high-fidelity quantum operations.
arxiv pdf

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