Ziyue Hua

Dynamic compensation for pump-induced frequency shift in Kerr-cat qubit initialization

  1. Yifang Xu,
  2. Ziyue Hua,
  3. Weiting Wang,
  4. Yuwei Ma,
  5. Ming Li,
  6. Jiajun Chen,
  7. Jie Zhou,
  8. Xiaoxuan Pan,
  9. Lintao Xiao,
  10. Hongwei Huang,
  11. Weizhou Cai,
  12. Hao Ai,
  13. Yu-xi Liu,
  14. Chang-Ling Zou,
  15. and Luyan Sun
The noise-biased Kerr-cat qubit is an attractive candidate for fault-tolerant quantum computation; however, its initialization faces challenges due to the squeezing pump-induced frequency
shift (PIFS). Here, we propose and demonstrate a dynamic compensation method to mitigate the effect of PIFS during the Kerr-cat qubit initialization. Utilizing a novel nonlinearity-engineered triple-loop SQUID device, we realize a stabilized Kerr-cat qubit and validate the advantages of the dynamic compensation method by improving the initialization fidelity from 57% to 78%, with a projected fidelity of 91% after excluding state preparation and measurement errors. Our results not only advance the practical implementation of Kerr-cat qubits, but also provide valuable insights into the fundamental adiabatic dynamics of these systems. This work paves the way for scalable quantum processors that leverage the bias-preserving properties of Kerr-cat qubits.
arxiv pdf

Experimental implementation of universal nonadiabatic geometric quantum gates in a superconducting circuit

  1. Yuan Xu,
  2. Ziyue Hua,
  3. Tao Chen,
  4. Xiaoxuan Pan,
  5. Xuegang Li,
  6. Jiaxiu Han,
  7. Weizhou Cai,
  8. Yuwei Ma,
  9. Haiyan Wang,
  10. Yipu Song,
  11. Zheng-Yuan Xue,
  12. and Luyan Sun
Using geometric phases to realize noise-resilient quantum computing is an important method to enhance the control fidelity. In this work, we experimentally realize a universal nonadiabatic
geometric quantum gate set in a superconducting qubit chain. We characterize the realized single- and two-qubit geometric gates with both quantum process tomography and randomized benchmarking methods. The measured average fidelities for the single-qubit rotation gates and two-qubit controlled-Z gate are 0.9977 and 0.977, respectively. Besides, we also experimentally demonstrate the noise-resilient feature of the realized single-qubit geometric gates by comparing their performance with the conventional dynamic gates with different types of errors in the control field. Thus, our experiment proves a way to achieve high-fidelity geometric quantum gates for robust quantum computation.
arxiv pdf