Xiangmin Yu

Experimental Realization of Universal Time-optimal non-Abelian Geometric Gates

  1. Zhikun Han,
  2. Yuqian Dong,
  3. Baojie Liu,
  4. Xiaopei Yang,
  5. Shuqing Song,
  6. Luqing Qiu,
  7. Danyu Li,
  8. Ji Chu,
  9. Wen Zheng,
  10. Jianwen Xu,
  11. Tianqi Huang,
  12. Zhimin Wang,
  13. Xiangmin Yu,
  14. Xinsheng Tan,
  15. Dong Lan,
  16. Man-Hong Yung,
  17. and Yang Yu
Based on the geometrical nature of quantum phases, non-adiabatic holonomic quantum control (NHQC) has become a standard technique for enhancing robustness in constructing quantum gates.
However, the conventional approach of NHQC is sensitive to control instability, as it requires the driving pulses to cover a fixed pulse area. Furthermore, even for small-angle rotations, all operations need to be completed with the same duration of time. Here we experimentally demonstrate a time-optimal and unconventional approach of NHQC (called TOUNHQC), which can optimize the operation time of any holonomic gate. Compared with the conventional approach, TOUNHQC provides an extra layer of robustness to decoherence and control errors. The experiment involves a scalable architecture of superconducting circuit, where we achieved a fidelity of 99.51% for a single qubit gate using interleaved randomized benchmarking. Moreover, a two-qubit holonomic control-phase gate has been implemented where the gate error can be reduced by as much as 18% compared with NHQC.
arxiv pdf

Realization of Superadiabatic Two-qubit Gates Using Parametric Modulation in Superconducting Circuits

  1. Ji Chu,
  2. Danyu Li,
  3. Xiaopei Yang,
  4. Shuqing Song,
  5. Zhikun Han,
  6. Zhen Yang,
  7. Yuqian Dong,
  8. Wen Zheng,
  9. Zhimin Wang,
  10. Xiangmin Yu,
  11. Dong Lan,
  12. Xinsheng Tan,
  13. and Yang Yu
We propose a protocol to realize parametric control of two-qubit coupling, where the amplitude and phase are tuned by a longitudinal field. Based on the tunable Hamiltonian, we demonstrate
the superadiabatic two-qubit quantum gate using superconducting quantum circuits. Our experimental results show that the state of qubits evolves adiabatically during the gate operation even though the processing time is close to the quantum limit. In addition, the quantum state transition is insensitive to the variation of control parameters, and the fidelity of a SWAP gate achieved 98.5%. This robust parametric two-qubit gate can alleviate the tension of frequency crowding for quantum computation with multiple qubits.
arxiv pdf