Probing Many-Body Bell Correlation Depth with Superconducting Qubits

Physical Review X, vol. 15

Abstract

Quantum nonlocality describes a stronger form of quantum correlation than that of entanglement. It refutes Einstein’s belief of local realism and is among the most distinctive and enigmatic features of quantum mechanics. It is a crucial resource for achieving quantum advantages in a variety of practical applications, ranging from cryptography and certified random number generation via self-testing to machine learning. Nevertheless, the detection of nonlocality, especially in quantum many-body systems, is notoriously challenging. Here, we report an experimental certification of genuine multipartite Bell-operator correlations, which signal nonlocality in quantum many-body systems, up to 24 qubits with a fully programmable superconducting quantum processor. In particular, we employ energy as a Bell-operator correlation witness and variationally decrease the energy of a many-body system across a hierarchy of thresholds, below which an increasing Bell-operator correlation depth can be certified from experimental data. We variationally prepare the low-energy state of a two-dimensional honeycomb model with 73 qubits and certify its Bell-operator correlations by measuring an energy that surpasses the corresponding classical bound with up to 48 standard deviations. In addition, we variationally prepare a sequence of low-energy states and certify their genuine multipartite Bell-operator correlations up to 24 qubits via energies measured efficiently by parity oscillation and multiple quantum coherence techniques. Our results establish a viable approach for preparing and certifying multipartite Bell-operator correlations, which provide not only a finer benchmark beyond entanglement for quantum devices, but also a valuable guide toward exploiting multipartite Bell correlations in a wide spectrum of practical applications.

Authors 36

1. Ke Wang corresponding

   Zhejiang University

   Affiliation as printed

   Zhejiang University

2. Weikang Li corresponding Aachen

   Leiden University · Tsinghua University

   Affiliation as printed

   Applied Quantum Algorithms Leiden

   Tsinghua University

   Universiteit Leiden

3. Shibo Xu corresponding

   Zhejiang University

   Affiliation as printed

   Zhejiang University

4. Mengyao Hu Aachen

   Leiden University

   Affiliation as printed

   Applied Quantum Algorithms Leiden

   Universiteit Leiden

5. Jiachen Chen

   Zhejiang University

   Affiliation as printed

   Zhejiang University

6. Yaozu Wu

   Zhejiang University

   Affiliation as printed

   Zhejiang University

7. Chuanyu Zhang

   Zhejiang University

   Affiliation as printed

   Zhejiang University

8. Feitong Jin

   Zhejiang University

   Affiliation as printed

   Zhejiang University

9. Xuhao Zhu

   Zhejiang University

   Affiliation as printed

   Zhejiang University

10. Yu Qing Gao

    Zhejiang University

    Affiliation as printed

    Zhejiang University

11. Ziqi Tan

    Zhejiang University

    Affiliation as printed

    Zhejiang University

12. Zhengyi Cui

    Zhejiang University

    Affiliation as printed

    Zhejiang University

13. Aosai Zhang

    Zhejiang University

    Affiliation as printed

    Zhejiang University

14. Ning Wang

    Zhejiang University

    Affiliation as printed

    Zhejiang University

15. Yiren Zou

    Zhejiang University

    Affiliation as printed

    Zhejiang University

16. Tingting Li

    Zhejiang University

    Affiliation as printed

    Zhejiang University

17. Fanhao Shen

    Zhejiang University

    Affiliation as printed

    Zhejiang University

18. Jiarun Zhong

    Zhejiang University

    Affiliation as printed

    Zhejiang University

19. Zehang Bao

    Zhejiang University

    Affiliation as printed

    Zhejiang University

20. Zitian Zhu

    Zhejiang University

    Affiliation as printed

    Zhejiang University

21. Zixuan Song

    Zhejiang University

    Affiliation as printed

    Zhejiang University

22. Jinfeng Deng

    Zhejiang University

    Affiliation as printed

    Zhejiang University

23. Hang Dong

    Zhejiang University

    Affiliation as printed

    Zhejiang University

24. Xu Zhang

    Zhejiang University

    Affiliation as printed

    Zhejiang University

25. Pengfei Zhang

    Zhejiang University

    Affiliation as printed

    Zhejiang University

26. Wenjie Jiang

    Tsinghua University

    Affiliation as printed

    Tsinghua University

27. Zhide Lu

    Shanghai Qi Zhi Institute · Tsinghua University

    Affiliation as printed

    Shanghai Qi Zhi Institute

    Tsinghua University

28. Zheng-Zhi Sun

    Tsinghua University

    Affiliation as printed

    Tsinghua University

29. Hekang Li

    Zhejiang University

    Affiliation as printed

    Zhejiang University

30. Qiujiang Guo

    Zhejiang University

    Affiliation as printed

    Hefei National Laboratory

    Zhejiang University

31. Zhen Wang

    Zhejiang University

    Affiliation as printed

    Hefei National Laboratory

    Zhejiang University

32. Patrick Emonts Aachen

    Leiden University

    Affiliation as printed

    Applied Quantum Algorithms Leiden

    Universiteit Leiden

33. Jordi Tura Aachen

    Leiden University

    Affiliation as printed

    Applied Quantum Algorithms Leiden

    Universiteit Leiden

34. Chao Song

    Zhejiang University

    Affiliation as printed

    Hefei National Laboratory

    Zhejiang University

35. H. Wang

    Zhejiang University

    Affiliation as printed

    Hefei National Laboratory

    Zhejiang University

36. Dong-Ling Deng

    Shanghai Qi Zhi Institute · Tsinghua University

    Affiliation as printed

    Hefei National Laboratory

    Shanghai Qi Zhi Institute

    Tsinghua University