By using the dry etching process of tantalum (Ta) film, we had obtained transmon qubit with the best lifetime (T1) 503 us, suggesting that the dry etching process can be adopted in the following multi-qubit fabrication with Ta film. We also compared the relaxation and coherence times of transmons made with different materials (Ta, Nb and Al) with the same design and fabrication processes of Josephson junction, we found that samples prepared with Ta film had the best performance, followed by those with Al film and Nb film. We inferred that the reason for this difference was due to the different loss of oxide materials located at the metal-air interface.
Cite
@article{arxiv.2105.09890,
title = {Transmon qubit with relaxation time exceeding 0.5 milliseconds},
author = {Chenlu Wang and Xuegang Li and Huikai Xu and Zhiyuan Li and Junhua Wang and Zhen Yang and Zhenyu Mi and Xuehui Liang and Tang Su and Chuhong Yang and Guangyue Wang and Wenyan Wang and Yongchao Li and Mo Chen and Chengyao Li and Kehuan Linghu and Jiaxiu Han and Yingshan Zhang and Yulong Feng and Yu Song and Teng Ma and Jingning Zhang and Ruixia Wang and Peng Zhao and Weiyang Liu and Guangming Xue and Yirong Jin and Haifeng Yu},
journal= {arXiv preprint arXiv:2105.09890},
year = {2023}
}