Low-loss interconnects for modular superconducting quantum processors

Journal Article · Thu Feb 16 00:00:00 EST 2023 · Nature Electronics

DOI:https://doi.org/10.1038/s41928-023-00925-z· OSTI ID:1989368

Niu, Jingjing ^[1]; Zhang, Libo ^[2]; Liu, Yang ^[2]; Qiu, Jiawei ^[2]; Huang, Wenhui ^[2]; Huang, Jiaxiang ^[2]; Jia, Hao ^[2]; Liu, Jiawei ^[2]; Tao, Ziyu ^[2]; Wei, Weiwei ^[2]; Zhou, Yuxuan ^[2]; Zou, Wanjing ^[2]; Chen, Yuanzhen ^[2]; Deng, Xiaowei ^[2]; Deng, Xiuhao ^[2]; Hu, Changkang ^[2]; Hu, Ling ^[2]; Li, Jian ^[2]; Tan, Dian ^[2]; Xu, Yuan ^[1] ; Yan, Fei ^[2]; Yan, Tongxing ^[2]; Liu, Song ^[1]; Zhong, Youpeng ^[1]; Cleland, Andrew N. ^[3]; Yu, Dapeng ^[1]

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1. Southern University of Science and Technology (SUSTech), Shenzhen (China); International Quantum Academy, Shenzhen (China); Hefei National Laboratory, Shenzhen (China)
2. Southern University of Science and Technology (SUSTech), Shenzhen (China); International Quantum Academy, Shenzhen (China)
3. Univ. of Chicago, IL (United States); Argonne National Laboratory (ANL), Argonne, IL (United States). Center for Molecular Engineering

Low-loss superconducting aluminium cables and on-chip impedance transformers can be used to link qubit modules and create superconducting quantum computing networks with high-fidelity intermodule state transfer. Scaling is now a key challenge in superconducting quantum computing. One solution is to build modular systems in which smaller-scale quantum modules are individually constructed and calibrated and then assembled into a larger architecture. This, however, requires the development of suitable interconnects. Here we report low-loss interconnects based on pure aluminium coaxial cables and on-chip impedance transformers featuring quality factors of up to 8.1 x 10⁵, which is comparable with the performance of our transmon qubits fabricated on a single-crystal sapphire substrate. We use these interconnects to link five quantum modules with intermodule quantum state transfer and Bell state fidelities of up to 99%. To benchmark the overall performance of the processor, we create maximally entangled, multiqubit Greenberger-Horne-Zeilinger states. The generated intermodule four-qubit Greenberger-Horne-Zeilinger state exhibits 92.0% fidelity. We also entangle up to 12 qubits in a Greenberger-Horne-Zeilinger state with 55.8 ± 1.8% fidelity, which is above the genuine multipartite entanglement threshold of 1/2.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: Guangdong Provincial Key Laboratory; Key Area Research and Development Program of Guangdong Province; National Natural Science Foundation of China (NSFC); National Science Foundation of Beijing; Science, Technology and Innovation Commission of Shenzhen Municipality; Shenzhen-Hong Kong Cooperation Zone for Technology and Innovation; USDOE
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1989368
• Journal Information: Nature Electronics, Journal Name: Nature Electronics Journal Issue: 3 Vol. 6; ISSN 2520-1131
• Publisher: Springer Nature
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Quantum information
Qubits