Suppressing Coherent Two-Qubit Errors via Dynamical Decoupling

  1. Jiawei Qiu,
  2. Yuxuan Zhou,
  3. Chang-Kang Hu,
  4. Jiahao Yuan,
  5. Libo Zhang,
  6. Ji Chu,
  7. Wenhui Huang,
  8. Weiyang Liu,
  9. Kai Luo,
  10. Zhongchu Ni,
  11. Xianchuang Pan,
  12. Zhixuan Yang,
  13. Yimeng Zhang,
  14. Yuanzhen Chen,
  15. Xiu-Hao Deng,
  16. Ling Hu,
  17. Jian Li,
  18. Jingjing Niu,
  19. Yuan Xu,
  20. Tongxing Yan,
  21. Youpeng Zhong,
  22. Song Liu,
  23. Fei Yan,
  24. and Dapeng Yu
Scalable quantum information processing requires the ability to tune multi-qubit interactions. This makes the precise manipulation of quantum states particularly difficult for multi-qubit interactions because tunability unavoidably introduces sensitivity to fluctuations in the tuned parameters, leading to erroneous multi-qubit gate operations. The performance of quantum algorithms may be severely compromised by coherent multi-qubit errors. It is therefore imperative to understand how these fluctuations affect multi-qubit interactions and, more importantly, to mitigate their influence. In this study, we demonstrate how to implement dynamical-decoupling techniques to suppress the two-qubit analogue of the dephasing on a superconducting quantum device featuring a compact tunable coupler, a trending technology that enables the fast manipulation of qubit–qubit interactions. The pure-dephasing time shows an up to ~14 times enhancement on average when using robust sequences. The results are in good agreement with the noise generated from room-temperature circuits. Our study further reveals the decohering processes associated with tunable couplers and establishes a framework to develop gates and sequences robust against two-qubit errors.
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