Zhihui Peng

Tunable coupling of a quantum phononic resonator to a transmon qubit with flip-chip architecture

  1. Xinhui Ruan,
  2. Li Li,
  3. Guihan Liang,
  4. Silu Zhao,
  5. Jia-heng Wang,
  6. Yizhou Bu,
  7. Bingjie Chen,
  8. Xiaohui Song,
  9. Xiang Li,
  10. He Zhang,
  11. Jinzhe Wang,
  12. Qianchuan Zhao,
  13. Kai Xu,
  14. Heng Fan,
  15. Yu-xi Liu,
  16. Jing Zhang,
  17. Zhihui Peng,
  18. Zhongcheng Xiang,
  19. and Dongning Zheng
A hybrid system with tunable coupling between phonons and qubits shows great potential for advancing quantum information processing. In this work, we demonstrate strong and tunable
coupling between a surface acoustic wave (SAW) resonator and a transmon qubit based on galvanic-contact flip-chip technique. The coupling strength varies from 2π×7.0 MHz to -2π×20.6 MHz, which is extracted from different vacuum Rabi oscillation frequencies. The phonon-induced ac Stark shift of the qubit at different coupling strengths is also shown. Our approach offers a good experimental platform for exploring quantum acoustics and hybrid systems.
arxiv pdf

Dynamics and Resonance Fluorescence from a Superconducting Artificial Atom Doubly Driven by Quantized and Classical Fields

  1. Xinhui Ruan,
  2. Jia-Heng Wang,
  3. Dong He,
  4. Pengtao Song,
  5. Shengyong Li,
  6. Qianchuan Zhao,
  7. L.M. Kuang,
  8. Jaw-Shen Tsai,
  9. Chang-Ling Zou,
  10. Jing Zhang,
  11. Dongning Zheng,
  12. O. V. Astafiev,
  13. Yu-xi Liu,
  14. and Zhihui Peng
We report an experimental demonstration of resonance fluorescence in a two-level superconducting artificial atom under two driving fields coupled to a detuned cavity. One of the fields
is classical and the other is varied from quantum (vacuum fluctuations) to classical one by controlling the photon number inside the cavity. The device consists of a transmon qubit strongly coupled to a one-dimensional transmission line and a coplanar waveguide resonator. We observe a sideband anti-crossing and asymmetry in the emission spectra of the system through a one-dimensional transmission line, which is fundamentally different from the weak coupling case. By changing the photon number inside the cavity, the emission spectrum of our doubly driven system approaches to the case when the atom is driven by two classical bichromatic fields. We also measure the dynamical evolution of the system through the transmission line and study the properties of the first-order correlation function, Rabi oscillations and energy relaxation in the system. The study of resonance fluorescence from an atom driven by two fields promotes understanding decoherence in superconducting quantum circuits and may find applications in superconducting quantum computing and quantum networks.
arxiv pdf

Tunable Microwave Single-photon Source Based on Transmon Qubit with High Efficiency

  1. Yu Zhou,
  2. Zhihui Peng,
  3. Yuta Horiuchi,
  4. O. V. Astafiev,
  5. and J. S. Tsai
Single-photon sources are of great interest because they are key elements in different promising applications of quantum technologies. Here we demonstrate a highly efficient tunable
on-demand microwave single-photon source based on a transmon qubit with the intrinsic emission efficiency more than 99%. To confirm the single-photon property of the source, we study the single-photon interference in a Hanbury-Brown-Twiss (HBT) type setup and measure the correlation functions of the emission field using linear detectors with a GPU-enhanced signal processing technique. The antibunching in the second-order correlation function is clearly observed. The theoretical calculations agree well with the experimental results. Such a high-quality single-photon source can be used as a building block of devices for quantum communication, simulations and information processing in the microwave regime.
arxiv pdf