From Fabrication to Characterization: Developing High-Quality Superconducting Qubits
Wei-En Lin3, Chen-Hsun Ma2, Li-Chieh Hsiao5, Zhen-Wei Xu1, Yu-Chiao Huang2, Han-Yu Lu1, Wei-Lun Peng4, Yueh-Nan Chen5, Hsi-Sheng Goan2, Chii-Dong Chen1, Cen-Shawn Wu4, Yung-Fu Chen3, Chung-Ting Ke1*
1Research Center for Critical Issues, Academia Sinica, Tainan, Taiwan
2Department of Physics, National Taiwan University, Taipei, Taiwan
3Department of Physics, National Central University, Taoyuan, Taiwan
4Department of Physics, National Changhua University of Education, Changhua, Taiwan
5Department of Physics, National Cheng Kung University, Tainan, Taiwan
* Presenter:Chung-Ting Ke, email:ctke@gate.sinica.edu.tw
High-quality superconducting qubits are essential for realizing fault-tolerant quantum computation. Achieving such high performance requires not only a clean fabrication process but also an optimized measurement environment. In this talk, we introduce a new fabrication flow that enables us to achieve energy relaxation times (T₁) as long as 336 μs. This process significantly reduces the area exposed to fabrication resist, thereby suppressing losses originating from two-level systems, particularly at the metal–substrate interface. Moreover, the fabrication method is inherently scalable, offering a promising pathway toward high-quality, large-scale quantum processing units (QPUs).
Additionally, we demonstrate that optimizing the measurement environment is equally crucial for improving qubit performance. By reducing infrared radiation and enhancing electromagnetic shielding, the average T₁ time of our QPU improves from 185 μs to 276 μs. Simultaneously, the qubit temperature decreases from 61 mK to 18 mK, accompanied by a reduction in quasiparticle density.
Our results present a comprehensive approach to developing high-quality superconducting qubits, addressing both fabrication and environmental optimization to advance scalable quantum computing.
Keywords: superconducting qubit , Two level system , quantum process unit