Probing Operator Spreading via Floquet Engineering in a Superconducting Circuit

  1. S. K. Zhao,
  2. Zi-Yong Ge,
  3. Zhongcheng Xiang,
  4. G. M. Xue,
  5. H. S. Yan,
  6. Z. T. Wang,
  7. Zhan Wang,
  8. H. K. Xu,
  9. F. F. Su,
  10. Z. H. Yang,
  11. He Zhang,
  12. Yu-Ran Zhang,
  13. Xue-Yi Guo,
  14. Kai Xu,
  15. Ye Tian,
  16. H. F. Yu,
  17. D. N. Zheng,
  18. Heng Fan,
  19. and S. P. Zhao
Operator spreading, often characterized by out-of-time-order correlators (OTOCs), is one of the central concepts in quantum many-body physics. However, measuring OTOCs is experimentally challenging due to the requirement of reversing the time evolution of the system. Here we apply Floquet engineering to investigate operator spreading in a superconducting 10-qubit chain. Floquet engineering provides an effective way to tune the coupling strength between nearby qubits, which is used to demonstrate quantum walks with tunable coupling, dynamic localization, reversed time evolution, and the measurement of OTOCs. A clear light-cone-like operator propagation is observed in the system with multiphoton excitations, and the corresponding spreading velocity is equal to that of quantum walk. Our results indicate that the method has a high potential for simulating a variety of quantum many-body systems and their dynamics, which is also scalable to more qubits and higher dimensional circuits.
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