Chii-Dong Chen

Slow and Stored Light via Electromagnetically Induced Transparency Using A Λ-type Superconducting Artificial Atom

  1. Kai-I Chu,
  2. Xiao-Cheng Lu,
  3. Kuan-Hsun Chiang,
  4. Yen-Hsiang Lin,
  5. Chii-Dong Chen,
  6. Ite A. Yu,
  7. Wen-Te Liao,
  8. and Yung-Fu Chen
Recent progresses in Josephson-junction-based superconducting circuits have propelled quantum information processing forward. However, the lack of a metastable state in most superconducting
artificial atoms hinders the development of photonic quantum memory in this platform. Here, we use a single superconducting qubit-resonator system to realize a desired Λ-type artificial atom, and to demonstrate slow light with a group velocity of 3.6 km/s and the microwave storage with a memory time extending to several hundred nanoseconds via electromagnetically induced transparency. Our results highlight the potential of achieving microwave quantum memory, promising substantial advancements in quantum information processing within superconducting circuits.
arxiv pdf

Characterizing Low-Quality-Factor Dissipative Superconducting Resonators

  1. Yu-Cheng Chang,
  2. Bayan Karimi,
  3. Jorden Senior,
  4. Alberto Ronzani,
  5. Joonas T. Peltonen,
  6. Hsi-Sheng Goan,
  7. Chii-Dong Chen,
  8. and Jukka P. Pekola
Characterizing superconducting microwave resonators with highly dissipative elements is a technical challenge, but a requirement for implementing and understanding the operation of
hybrid quantum devices involving dissipative elements, e.g. for thermal engineering and detection. We present experiments on λ/4 superconducting niobium coplanar waveguide (CPW) resonators, shunted at the antinode by a dissipative copper microstrip via aluminium leads, yielding a quality factor unresolvable from the typical microwave environment. By measuring the transmission both above and below this transition, we are able to isolate the resonance. We then experimentally verify this method with copper microstrips of increasing thicknesses, from 50 nm to 150 nm, and measure quality factors in the range of 10∼67 in a consistent way.
arxiv pdf