Zhihui Peng

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