Xiao-Yan Yang

Inverse designed Hamiltonians for perfect state transfer and remote entanglement generation, and applications in superconducting qubits

  1. Tian-Le Wang,
  2. Ze-An Zhao,
  3. Peng Wang,
  4. Sheng Zhang,
  5. Ren-Ze Zhao,
  6. Xiao-Yan Yang,
  7. Hai-Feng Zhang,
  8. Zhi-Fei Li,
  9. Yuan Wu,
  10. Peng Duan,
  11. Ming Gong,
  12. and Guo-Ping Guo
Hamiltonian inverse engineering enables the design of protocols for specific quantum evolutions or target state preparation. Perfect state transfer (PST) and remote entanglement generation
are notable examples, as they serve as key primitives in quantum information processing. However, Hamiltonians obtained through conventional methods often lack robustness against noise. Assisted by inverse engineering, we begin with a noise-resilient energy spectrum and construct a class of Hamiltonians, referred to as the dome model, that significantly improves the system’s robustness against noise, as confirmed by numerical simulations. This model introduces a tunable parameter m that modifies the energy-level spacing and gives rise to a well-structured Hamiltonian. It reduces to the conventional PST model at m=0 and simplifies to a SWAP model involving only two end qubits in the large-m regime. To address the challenge of scalability, we propose a cascaded strategy that divides long-distance PST into multiple consecutive PST steps. Our work is particularly suited for demonstration on superconducting qubits with tunable couplers, which enable rapid and flexible Hamiltonian engineering, thereby advancing the experimental potential of robust and scalable quantum information processing.
arxiv pdf

Spectator Leakage Elimination in CZ Gates via Tunable Coupler Interference on a Superconducting Quantum Processor

  1. Peng Wang,
  2. Bin-Han Lu,
  3. Tian-Le Wang,
  4. Sheng Zhang,
  5. Zhao-Yun Chen,
  6. Hai-Feng Zhang,
  7. Ren-Ze Zhao,
  8. Xiao-Yan Yang,
  9. Ze-An Zhao,
  10. Zhuo-Zhi Zhang,
  11. Xiang-Xiang Song,
  12. Yu-Chun Wu,
  13. Peng Duan,
  14. and Guo-Ping Guo
Spectator-induced leakage poses a fundamental challenge to scalable quantum computing, particularly as frequency collisions become unavoidable in multi-qubit processors. We introduce
a leakage mitigation strategy based on dynamically reshaping the system Hamiltonian. Our technique utilizes a tunable coupler to enforce a block-diagonal structure on the effective Hamiltonian governing near-resonant spectator interactions, confining the gate dynamics to a two-dimensional invariant subspace and thus preventing leakage by construction. On a multi-qubit superconducting processor, we experimentally demonstrate that this dynamic control scheme suppresses leakage rates to the order of 10−4 across a wide near-resonant detuning range. The method also scales effectively with the number of spectators. With three simultaneous spectators, the total leakage remains below the threshold relevant for surface code error correction. This approach eases the tension between dense frequency packing and high-fidelity gate operation, establishing dynamic Hamiltonian engineering as an essential tool for advancing fault-tolerant quantum computing.
arxiv pdf