Fabrication and characterization of superconducting multiqubit device with niobium base layer
Feifan Su(宿非凡)1, Zhaohua Yang(杨钊华)1,2, Shoukuan Zhao(赵寿宽)1,2, Haisheng Yan(严海生)1,2, Ziting Wang(王子婷)1,2, Xiaohui Song(宋小会)1, Ye Tian(田野)1, and Shiping Zhao(赵士平)1,2,3,4,†
1 Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; 2 School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China; 3 Chinese Academy of Sciences Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China; 4 Songshan Lake Materials Laboratory, Dongguan 523808, China
Abstract Superconducting transmon qubits are the leading platform in solid-state quantum computing and quantum simulation applications. In this work, we develop a fabrication process for the transmon multiqubit device with a niobium base layer, shadow-evaporated Josephson junctions, and airbridges across the qubit control lines to suppress crosstalk. Our results show that these multiqubit devices have well-characterized readout resonators, and that the energy relaxation and Ramsey (spin-echo) dephasing times are up to ～ 40 μs and 14 (47) μs, respectively. We perform single-qubit gate operations that demonstrate a maximum gate fidelity of 99.97%. In addition, two-qubit vacuum Rabi oscillations are measured to evaluate the coupling strength between qubits, and the crosstalk among qubits is found to be less than 1% with the fabricated airbridges. Further improvements in qubit coherence performance using this fabrication process are also discussed.
Fund: Project supported by the National Key R&D Program of China (Grant No. 2016YFA0300601), the National Natural Science Foundation of China (Grant Nos. 11934018 and 11874063), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB28000000), and the Key-Area Research and Development Program of GuangDong Province, China (Grant No. 2018B030326001).
Feifan Su(宿非凡), Zhaohua Yang(杨钊华), Shoukuan Zhao(赵寿宽), Haisheng Yan(严海生), Ziting Wang(王子婷), Xiaohui Song(宋小会), Ye Tian(田野), and Shiping Zhao(赵士平) Fabrication and characterization of superconducting multiqubit device with niobium base layer 2021 Chin. Phys. B 30 100304
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