Towards practical quantum computers: transmon qubit with a lifetime approaching 0.5 milliseconds

• Published in: npj quantum information Vol. 8; no. 1; pp. 1 - 6
• Main Authors: Wang, Chenlu, Li, Xuegang, Xu, Huikai, Li, Zhiyuan, Wang, Junhua, Yang, Zhen, Mi, Zhenyu, Liang, Xuehui, Su, Tang, Yang, Chuhong, Wang, Guangyue, Wang, Wenyan, Li, Yongchao, Chen, Mo, Li, Chengyao, Linghu, Kehuan, Han, Jiaxiu, Zhang, Yingshan, Feng, Yulong, Song, Yu, Ma, Teng, Zhang, Jingning, Wang, Ruixia, Zhao, Peng, Liu, Weiyang, Xue, Guangming, Jin, Yirong, Yu, Haifeng
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 13-01-2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/119/1003; 639/766/483/2802; 639/766/483/481; Aluminum; Classical and Quantum Gravitation; Computers; Etching; Physics; Physics and Astronomy; Quantum Computing; Quantum Field Theories; Quantum Information Technology; Quantum Physics; Relativity Theory; Spintronics; String Theory; Tantalum
• ISSN: 2056-6387; 2056-6387
• DOI: 10.1038/s41534-021-00510-2

Here we report a breakthrough in the fabrication of a long lifetime transmon qubit. We use tantalum films as the base superconductor. By using a dry etching process, we obtained transmon qubits with a best
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lifetime of 503 μs. As a comparison, we also fabricated transmon qubits with other popular materials, including niobium and aluminum, under the same design and fabrication processes. After characterizing their coherence properties, we found that qubits prepared with tantalum films have the best performance. Since the dry etching process is stable and highly anisotropic, it is much more suitable for fabricating complex scalable quantum circuits, when compared to wet etching. As a result, the current breakthrough indicates that the dry etching process of tantalum film is a promising approach to fabricate medium- or large-scale superconducting quantum circuits with a much longer lifetime, meeting the requirements for building practical quantum computers.