Jie Zhou

Single-photon scattering in a dissipative superconducting-qubit–SSH lattice hybrid

  1. Xiao-Xue Zhang,
  2. Jie Zhou,
  3. and Xi-Zheng Zhang
We study single-photon scattering in a Su–Schrieffer–Heeger (SSH) photonic lattice locally coupled to a superconducting qubit with tunable loss or gain. Working in the single-excitation
sector, we derive an explicit real-space scattering formulation for the full energy-dependent scattering matrix S(E) and identify how its eigenvalues encode coherent perfect absorption, amplification, and spectral singular behavior. The analytical results are benchmarked against time-domain wave-packet simulations, which reproduce the stationary scattering probabilities with high accuracy. We show that the SSH dimerization, the qubit-induced non-Hermitian self-energy, and the synthetic gauge phase cooperate to reshape the reflection and transmission spectra in a highly selective way. In particular, changing the dimerization can switch the system between transmission-dominated and reflection-dominated regimes, while the flux provides a direct handle on interference and symmetry-controlled response. We also find a robust loss–gain correspondence in the reflection landscape and show that the linewidth broadening is governed predominantly by the magnitude |γ| of the non-Hermitian coupling. These results establish a compact and experimentally relevant framework for topological scattering in superconducting quantum networks.
arxiv pdf

Dynamic compensation for pump-induced frequency shift in Kerr-cat qubit initialization

  1. Yifang Xu,
  2. Ziyue Hua,
  3. Weiting Wang,
  4. Yuwei Ma,
  5. Ming Li,
  6. Jiajun Chen,
  7. Jie Zhou,
  8. Xiaoxuan Pan,
  9. Lintao Xiao,
  10. Hongwei Huang,
  11. Weizhou Cai,
  12. Hao Ai,
  13. Yu-xi Liu,
  14. Chang-Ling Zou,
  15. and Luyan Sun
The noise-biased Kerr-cat qubit is an attractive candidate for fault-tolerant quantum computation; however, its initialization faces challenges due to the squeezing pump-induced frequency
shift (PIFS). Here, we propose and demonstrate a dynamic compensation method to mitigate the effect of PIFS during the Kerr-cat qubit initialization. Utilizing a novel nonlinearity-engineered triple-loop SQUID device, we realize a stabilized Kerr-cat qubit and validate the advantages of the dynamic compensation method by improving the initialization fidelity from 57% to 78%, with a projected fidelity of 91% after excluding state preparation and measurement errors. Our results not only advance the practical implementation of Kerr-cat qubits, but also provide valuable insights into the fundamental adiabatic dynamics of these systems. This work paves the way for scalable quantum processors that leverage the bias-preserving properties of Kerr-cat qubits.
arxiv pdf