Qichun Liu

Gatemon qubit based on a thin InAs-Al hybrid nanowire

  1. Jierong Huo,
  2. Zezhou Xia,
  3. Zonglin Li,
  4. Shan Zhang,
  5. Yuqing Wang,
  6. Dong Pan,
  7. Qichun Liu,
  8. Yulong Liu,
  9. Zhichuan Wang,
  10. Yichun Gao,
  11. Jianhua Zhao,
  12. Tiefu Li,
  13. Jianghua Ying,
  14. Runan Shang,
  15. and Hao Zhang
We study a gate-tunable superconducting qubit (gatemon) based on a thin InAs-Al hybrid nanowire. Using a gate voltage to control its Josephson energy, the gatemon can reach the strong
coupling regime to a microwave cavity. In the dispersive regime, we extract the energy relaxation time T1∼0.56 μs and the dephasing time T∗2∼0.38 μs. Since thin InAs-Al nanowires can have fewer or single sub-band occupation and recent transport experiment shows the existence of nearly quantized zero-bias conductance peaks, our result holds relevancy for detecting Majorana zero modes in thin InAs-Al nanowires using circuit quantum electrodynamics.
arxiv pdf

Quantum coherence between cavity and artificial atom in a superconducting circuit QED ladder system

  1. Qichun Liu,
  2. Han Cai,
  3. Yingshan Zhang,
  4. Jianshe Liu,
  5. and Wei Chen
We have created a quantum three-level ladder system with the cavity dispersive energy level in a superconducting circuit quantum electrodynamics system consisting of a transmon qubit
and a cavity, and have directly observed the Autler-Townes splitting eff?ect instead of representing it by the probability of the qubit being at each level. A coupler tone is applied on the transition between the second excited state of transmon and cavity dispersive level, while the cavity spectrum is probed. A doublet transmission and anormalous dispersion spectrum of the cavity level is clearly shown. The inverse Fourier transform of cavity spectrum indicates that there is a quantum coherence Rabi oscillation of the populations between cavity and qubit.
arxiv pdf