Youwei Zhao

Realization of fast all-microwave CZ gates with a tunable coupler

  1. Shaowei Li,
  2. Daojin Fan,
  3. Ming Gong,
  4. Yangsen Ye,
  5. Xiawei Chen,
  6. Yulin Wu,
  7. Huijie Guan,
  8. Hui Deng,
  9. Hao Rong,
  10. He-Liang Huang,
  11. Chen Zha,
  12. Kai Yan,
  13. Shaojun Guo,
  14. Haoran Qian,
  15. Haibin Zhang,
  16. Fusheng Chen,
  17. Qingling Zhu,
  18. Youwei Zhao,
  19. Shiyu Wang,
  20. Chong Ying,
  21. Sirui Cao,
  22. Jiale Yu,
  23. Futian Liang,
  24. Yu Xu,
  25. Jin Lin,
  26. Cheng Guo,
  27. Lihua Sun,
  28. Na Li,
  29. Lianchen Han,
  30. Cheng-Zhi Peng,
  31. Xiaobo Zhu,
  32. and Jian-Wei Pan
The development of high-fidelity two-qubit quantum gates is essential for digital quantum computing. Here, we propose and realize an all-microwave parametric Controlled-Z (CZ) gates
by coupling strength modulation in a superconducting Transmon qubit system with tunable couplers. After optimizing the design of the tunable coupler together with the control pulse numerically, we experimentally realized a 100 ns CZ gate with high fidelity of 99.38%±0.34% and the control error being 0.1%. We note that our CZ gates are not affected by pulse distortion and do not need pulse correction, {providing a solution for the real-time pulse generation in a dynamic quantum feedback circuit}. With the expectation of utilizing our all-microwave control scheme to reduce the number of control lines through frequency multiplexing in the future, our scheme draws a blueprint for the high-integrable quantum hardware design.
arxiv pdf

Realization of high-fidelity CZ gates in extensible superconducting qubits design with a tunable coupler

  1. Yangsen Ye,
  2. Sirui Cao,
  3. Yulin Wu,
  4. Xiawei Chen,
  5. Qingling Zhu,
  6. Shaowei Li,
  7. Fusheng Chen,
  8. Ming Gong,
  9. Chen Zha,
  10. He-Liang Huang,
  11. Youwei Zhao,
  12. Shiyu Wang,
  13. Shaojun Guo,
  14. Haoran Qian,
  15. Futian Liang,
  16. Jin Lin,
  17. Yu Xu,
  18. Cheng Guo,
  19. Lihua Sun,
  20. Na Li,
  21. Hui Deng,
  22. Xiaobo Zhu,
  23. and Jian-Wei Pan
High-fidelity two-qubits gates are essential for the realization of large-scale quantum computation and simulation. Tunable coupler design is used to reduce the problem of parasitic
coupling and frequency crowding in many-qubit systems and thus thought to be advantageous. Here we design a extensible 5-qubit system in which center transmon qubit can couple to every four near-neighbor qubit via a capacitive tunable coupler and experimentally demonstrate high-fidelity controlled-phase (CZ) gate by manipulating center qubit and one near-neighbor qubit. Speckle purity benchmarking (SPB) and cross entrophy benchmarking (XEB) are used to assess the purity fidelity and the fidelity of the CZ gate. The average purity fidelity of the CZ gate is 99.69±0.04\% and the average fidelity of the CZ gate is 99.65±0.04\% which means the control error is about 0.04\%. Our work will help resovle many chanllenges in the implementation of large scale quantum systems.
arxiv pdf

Verification of a resetting protocol for an uncontrolled superconducting qubit

  1. Ming Gong,
  2. Feihu Xu,
  3. Zheng-Da Li,
  4. Zizhu Wang,
  5. Yu-Zhe Zhang,
  6. Yulin Wu,
  7. Shaowei Li,
  8. Youwei Zhao,
  9. Shiyu Wang,
  10. Chen Zha,
  11. Hui Deng,
  12. Zhiguang Yan,
  13. Hao Rong,
  14. Futian Liang,
  15. Jin Lin,
  16. Yu Xu,
  17. Cheng Guo,
  18. Lihua Sun,
  19. Anthony D. Castellano,
  20. Chengzhi Peng,
  21. Yu-Ao Chen,
  22. Xiaobo Zhu,
  23. and Jian-Wei Pan
We experimentally verify the simplest non-trivial case of a quantum resetting protocol with five superconducting qubits, testing it with different types of free evolutions and target-probe
interactions. After post-selection, we obtained a reset state fidelity as high as 0.951, and the process fidelity was found to be 0.792. We also implemented 100 randomly-chosen interactions and demonstrated an average success probability of 0.323, experimentally confirmed the non-zeros probability of success for unknown interactions; the numerical simulated value is 0.384. We anticipate this protocol will have widespread applications in quantum information processing science, since it is able to combat any form of free evolution.
arxiv pdf

Genuine 12-qubit entanglement on a superconducting quantum processor

  1. Ming Gong,
  2. Ming-Cheng Chen,
  3. Yarui Zheng,
  4. Shiyu Wang,
  5. Chen Zha,
  6. Hui Deng,
  7. Zhiguang Yan,
  8. Hao Rong,
  9. Yulin Wu,
  10. Shaowei Li,
  11. Fusheng Chen,
  12. Youwei Zhao,
  13. Futian Liang,
  14. Jin Lin,
  15. Yu Xu,
  16. Cheng Guo,
  17. Lihua Sun,
  18. Anthony D. Castellano,
  19. Haohua Wang,
  20. Chengzhi Peng,
  21. Chao-Yang Lu,
  22. Xiaobo Zhu,
  23. and Jian-Wei Pan
We report the preparation and verification of a genuine 12-qubit entanglement in a superconducting processor. The processor that we designed and fabricated has qubits lying on a 1D
chain with relaxation times ranging from 29.6 to 54.6 μs. The fidelity of the 12-qubit entanglement was measured to be above 0.5544±0.0025, exceeding the genuine multipartite entanglement threshold by 21 standard deviations. Our entangling circuit to generate linear cluster states is depth-invariant in the number of qubits and uses single- and double-qubit gates instead of collective interactions. Our results are a substantial step towards large-scale random circuit sampling and scalable measurement-based quantum computing.
arxiv pdf