‌Kai Xu

　　Kai Xu, male, hails from Yueyang, Hunan Province. He graduated with a bachelor’s degree from Central South University in June 2012 and earned his Ph.D. from Zhejiang University in June 2018. Then he joined the Solid-State Quantum Information and Computing Laboratory (Q03) at the Institute of Physics, Chinese Academy of Sciences (IOP, CAS), as an associate researcher. In 2020, he was promoted to doctoral supervisor and selected for the Chinese Academy of Sciences Youth Innovation Promotion Association. In 2022, he was recognized as a Beijing Science and Technology Rising Star, and in 2023, he received the National Natural Science Foundation of China’s Excellent Young Scientists Fund. He currently serves as a part-time associate researcher in the Cloud Quantum Computing Platform (CQCP) Team at the Beijing Academy of Quantum Information Sciences (BAQIS), where he is primarily responsible for planning and coordinating the team’s hardware and experimental efforts.

Education and Work Experience

　　2008.09–2012.06: Bachelor’s Degree in Applied Physics, School of Physics, Central South University

　　2012.09–2018.06: Ph.D. in Condensed Matter Physics, School of Physics, Zhejiang University

　　2018.07–Present: Associate Researcher, IOP, CAS

　　2021.01–Present: Doctoral Supervisor

　　2021.07–Present: Part-time Associate Researcher, BAQIS

Research Directions

　　Superconducting quantum computing (SQC) and quantum simulation.

Publications

　　His primary achievements lie in the fields of many-body quantum entanglement, quantum simulation of many-body systems, quantum logic gates, and CQCP. Notable accomplishments include:

　　In 2017, achieved entanglement of 10 superconducting qubits, setting a world record for multi-particle entanglement in solid-state systems at the time.

　　In 2019, realized a 20-qubit multi-component Schrödinger cat state, further breaking the world record for multi-particle entanglement.

　　In 2022, prepared and characterized non-Gaussian entangled states approaching the Heisenberg limit, achieving a leading advantage in quantum metrology.

　　In 2018, simulated many-body localization with 10 superconducting qubits.

　　In 2020, used 16 superconducting qubits to simulate dynamic phase transitions.

　　In 2022, implemented a controlled-NOT gate based on non-Abelian geometric phases in a superconducting circuit system for the first time.

　　Contributed to the development of the Quafu CQCP, overseeing the construction and integration of the experimental backend.

　　He has published over ten papers as first or corresponding author (including co-corresponding) in high-impact journals, including Science (1), Physical Review Letters (5), Nature Communications (5), Science Advances (1), Optica (1), and npj Quantum Information (2).

Selected Publications (#as a co-first author, *as a co-corresponding author):

[1] Yong-Yi Wang#, Yun-Hao Shi#, Zheng-Hang Sun#, Chi-Tong Chen, Zheng-An Wang, Kui Zhao, Hao-Tian Liu, Wei-Guo Ma, Ziting Wang, Hao Li, Jia-Chi Zhang, Yu Liu, Cheng-Lin Deng, Tian-Ming Li, Yang He, Zheng-He Liu, Zhen-Yu Peng, Xiaohui Song, Guangming Xue, Haifeng Yu, Kaixuan Huang*, Zhongcheng Xiang*, Dongning Zheng, Kai Xu*, and Heng Fang*, Exploring Hilbert-Space Fragmentation on a Superconducting Processor, PRX Quantum (2025).

[2] Cheng-Lin Deng#, Yu Liu#, Yu-Ran Zhang#, Xue-Gang Li, Tao Liu, Chi-Tong Chen, Tong Liu, Cong-Wei Lu, Yong-Yi Wang, Tian-Ming Li, Cai-Ping Fang, Si-Yun Zhou, Jia-Cheng Song, Yue-Shan Xu, Yang He, Zheng-He Liu, Kai-Xuan Huang, Zhong-Cheng Xiang, Jie-Ci Wang, Dong-Ning Zheng, Guang-Ming Xue, Kai Xu*, H. F. Yu*, Heng Fan*, High-order topological pumping on a superconducting quantum simulator, Physical Review Letters 133, 140402(2024).

[3] Yun-Hao Shi#, Zheng-Hang Sun#, Yong-Yi Wang#, Zheng-An Wang, Yu-Ran Zhang, Wei-Guo Ma, Hao-Tian Liu, Kui Zhao, Jia-Cheng Song, Gui-Han Liang, Zheng-Yang Mei, Jia-Chi Zhang, Hao Li, Chi-Tong Chen, Xiaohui Song, Jieci Wang, Guangming Xue, Haifeng Yu, Kaixuan Huang*, Zhongcheng Xiang*, Kai Xu*, Dongning Zheng, Heng Fan*, Probing spin hydrodynamics on a superconducting quantum simulator, Nature Communications 15, 7573 (2024).

[4] Gui-Han Liang#, Xiao-Hui Song#, Cheng-Lin Deng#, Xu-Yang Gu, Yu Yan, Zheng-Yang Mei, Si-Lu Zhao, Yi-Zhou Bu, Yong-Xi Xiao, Yi-Han Yu, Ming-Chuan Wang, Tong Liu, Yun-Hao Shi, He Zhang, Xiang Li, Li Li, Jing-Zhe Wang, Ye Tian, Shi-Ping Zhao, Kai Xu*, Heng Fan*, Zhong-Cheng Xiang*, Dong-Ning Zheng*, Tunable-coupling architectures with capacitively connecting pads for large-scale superconducting multiqubit processors, Physical Review Applied 20, 044028 (2023).

[5] Zhong-Cheng Xiang#, Kaixuan Huang#, Yu-Ran Zhang#, Tao Liu, Yun-Hao Shi, Cheng-Lin Deng, Tong Liu, Hao Li, Gui-Han Liang, Zheng-Yang Mei, Haifeng Yu, Guangming Xue, Ye Tian, Xiaohui Song, Zhi-Bo Liu, Kai Xu*, Dongning Zheng, Franco Nori*, Heng Fan*, Simulating Chern insulators on a superconducting quantum processor, Nature Communications 14, 5433 (2023).　

[6] Yun-Hao Shi#, Yu Liu#, Yu-Ran Zhang#, Zhongcheng Xiang#, Kaixuan Huang, Tao Liu, Yong-Yi Wang, Jia-Chi Zhang, Cheng-Lin Deng, Gui-Han Liang, Zheng-Yang Mei, Hao Li, Tian-Ming Li, Wei-Guo Ma, Hao-Tian Liu, Chi-Tong Chen, Tong Liu, Ye Tian, Xiaohui Song, S. P. Zhao, Kai Xu*, Dongning Zheng*, Franco Nori*, Heng Fan*, Quantum simulation of topological zero modes on a 41-qubit superconducting processor, Physical Review Letters 131, 080401 (2023).　

[7] Yun-Hao Shi#, Run-Qiu Yang#, ZhongchengXiang#, Zi-Yong Ge, Hao Li, Yong-Yi Wang, Kaixuan Huang, Ye Tian, Xiaohui Song, Dongning Zheng*, Kai Xu*, Rong-Gen Cai*, Heng Fan*, Quantum simulation of Hawking radiation and curved spacetime with a superconducting on-chip black hole, Nature Communications 14, 3263 (2023).　

[8] Tong Liu, Shang Liu, Hekang Li, Hao Li, Kaixuan Huang, Zhongcheng Xiang, Xiaohui Song, Kai Xu*, Dongning Zheng*, Heng Fan*, Observation of entanglement negativity transition of pseudo-random mixed states, Nature Communications 14, 1971 (2023).

[9] Hao Li#, Yong-Yi Wang#, Yun-Hao Shi, Kaixuan Huang, Xiaohui Song, Gui-Han Liang, Zheng-Yang Mei, Bozhen Zhou, He Zhang, Jia-Chi Zhang, Shu Chen, Shiping Zhao, Ye Tian, Zhan-Ying Yang, Zhongcheng Xiang, Kai Xu*, Dongning Zheng*, Heng Fan*, Observation of critical phase transition in a generalized Aubry-André-Harper model on a superconducting quantum processor with tunable couplers, npj Quantum Information 9, 40 (2023).

[10] Kaixuan Huang, Xiaoxia Cai, Hao Li, Zi-Yong Ge, Ruijuan Hou, Hekang Li, Tong Liu, Yunhao Shi, Chitong Chen, Dongning Zheng, Kai Xu*, Zhi-Bo Liu*, Zhendong Li*, Heng Fan*, and Wei-Hai Fang, Variational Quantum Computation of Molecular Linear Response Properties on a Superconducting Quantum Processor, The Journal of Physical Chemistry Letters 13, 9114 (2022).　

[11] Chi-Tong Chen, Yun-Hao Shi, Zhongcheng Xiang, Zheng-An Wang, Tian-Ming Li, Hao-Yu Sun, Tian-Shen He, Xiaohui Song, Shiping Zhao, Dongning Zheng, Kai Xu*, Heng Fan*, ScQ cloud quantum computation for generating Greenberger-Horne-Zeilinger states of up to 10 qubits, Science China – Phys. Mech. & Astron. 65, 110362 (2022).

[12] Kai Xu#, Yu-Ran Zhang#, Zheng-Hang Sun#, Hekang Li, Pengtao Song, Zhongcheng Xiang, Kaixuan Huang, Hao Li, Yun-Hao Shi, Chi-Tong Chen, Xiaohui Song, Dongning Zheng, Franco Nori*, H. Wang*, and Heng Fan*, Metrological characterization of non-Gaussian entangled states of superconducting qubits, Physical Review Letters 128, 150501 (2022).

[13] Kai Xu, Wen Ning, Xin-Jie Huang, Pei-Rong Han, Hekang Li, Zhen-Biao Yang, Dongning Zheng, Heng Fan, and Shi-Biao Zheng, Demonstration of a non-Abelian geometric controlled-NOT gate in a superconducting circuit, Optica 8, 972-976 (2021).　

[14] Zhen-Biao Yang, Pei-Rong Han, Xin-Jie Huang, Wen Ning, Hekang Li, Kai Xu*, Dongning Zheng, Heng Fan* & Shi-Biao Zheng*, Experimental demonstration of entanglement-enabled universal quantum cloning in a circuit, npj Quantum Information 7: 44 (2021).

[15] Kai Xu#, Zheng-Hang Sun#, Wuxin Liu#, Yu-Ran Zhang, Hekang Li, Hang Dong, Wenhui Ren, Pengfei Zhang, Franco Nori, Dongning Zheng*, Heng Fan*, H. Wang*, Probing dynamical phase transitions with a superconducting quantum simulator, Science Advances 6, eaba4935 (2020).　

[16] C. Song#, Kai Xu#, H. K. Li#, Y.-R. Zhang, X. Zhang, W. X. Liu, Q. J. Guo, Z. Wang, W. H. Ren, J. Hao, H. Feng, H. Fan*, D. N. Zheng*, D.-W. Wang, H. Wang*, S.-Y. Zhu, Generation of multicomponent atomic Schrödinger cat states of up to 20 qubits, Science 365, 574 (2019). (SCI高引)　

[17] W. Ning, X.-J. Huang, P.-R. Han, H. K. Li, H. Deng, Z.-B. Yang*, Z-R. Zhong, Y. Xia, Kai Xu*, D. N. Zheng, and S.-B. Zheng*, Deterministic Entanglement Swapping in a Superconducting Circuit, Physical Review Letters 123, 060502 (2019).

[18] Kai Xu#, J. J. Chen#, Y. Zeng, Y. R. Zhang, C. Song, W. X. Liu, Q. J. Guo, P. F. Zhang, D. Xu, H. Deng, K. Q. Huang, H. Wang*, X. B. Zhu*, D. N. Zheng, H. Fan*, Emulating Many-Body Localization with a Superconducting Quantum Processor, Physical Review Letters 120, 050507 (2018). (SCI高引)

[19] C. Song#, Kai Xu#, W. X. Liu, C. P. Yang, S. B. Zheng*, H. Deng, Q. W. Xie, K. Q. Huang, Q. J. Guo, L. B. Zhang, P. F. Zhang, D. Xu, D. N. Zheng, X. B. Zhu*, H. Wang*, Y. A. Chen, C. Y. Lu, S. Y. Han, J. W. Pan, 10-Qubit Entanglement and Parallel Logic Operations with a Superconducting Circuit, Physical Review Letters 119, 180511 (2017). (SCI高引，编辑推荐)　　

[20] D. V. Averin*, Kai Xu, Y. P. Zhong, C. Song, H. Wang*, S. Y. Han*, Suppression of Dephasing by Qubit Motion in Superconducting Circuits, Physical Review Letters 116, 010501 (2016).

[21] S. B. Zheng*, Y. P. Zhong, Kai Xu, Q. J. Wang, H. Wang, L. T. Shen, C. P. Yang, J. M. Martinis*, A. N. Cleland*, S. Y. Han, Emulating Quantum Delayed-Choice Experiment with a Beam Splitter in a Quantum Superposition, Physical Review Letters 115, 260403 (2015).

[22] C. Song, S. B. Zheng*, P. F. Zhang, Kai Xu, L. B. Zhang, Q. J. Guo, W. X. Liu, D. Xu, H. Deng, K. Q. Huang, D. N. Zheng, X. B. Zhu*, H. Wang*, Continuous-variable geometric phase and its manipulation for quantum computation in a superconducting circuit, Nature Communications 8, 1061 (2017).　

[23] Y. P. Zhong, D. Xu, P. Wang, C. Song, Q. J. Guo, W. X. Liu, Kai Xu, B. X. Xia, C. Y. Lu*, S. Y. Han, J. W. Pan*, H. Wang*, Emulating Anyonic Fractional Statistical Behavior in a Superconducting Quantum Circuit, Physical Review Letters 117, 110501 (2016).

[24] C. Song, D. Xu, P. F. Zhang, J. W. Wang, Q. J. Guo, W. X. Liu, Kai Xu, H. Deng, K. Q. Huang, D. N. Zheng, S.-B. Zheng, H. Wang*, X. B. Zhu*, C.-Y. Lu*, and J.-W. Pan. Demonstration of Topological Robustness of Anyonic Braiding Statistics with a Superconducting Quantum Circuit, Physical Review Letters 121, 030502 (2018).

[25] T. X. Yan#, B.-J. Liu#, Kai Xu, C. Song, S. Liu, Z. S. Zhang, H. Deng, Z. G. Yan, H. Rong, K. Q. Huang, M.-H. Yung*, Y. Z. Chen*, and D. P. Yu, Experimental Realization of Nonadiabatic Shortcut to Non-Abelian Geometric Gates, Physical Review Letters 122, 080501 (2019).　

[26] Kai Xu#, X. Y. LinPeng#, Z. L. Wang*. Decoherence suppression combining quantum uncollapsing and dynamical decoupling. Applied Physics Letters 104, 263509 (2014).

Projects and Grants

　　◇ National Natural Science Foundation of China Youth Fund Project, 270,000 RMB, completed.

　　◇ National Natural Science Foundation of China Major Research Plan Cultivation Project, 800,000 RMB, completed.

　　◇ Beijing Natural Science Foundation Key Project (sub-project leader, 1.5 million RMB), completed.

　　◇ Chinese Academy of Sciences Youth Innovation Promotion Association, 800,000 RMB, completed.

　　◇ Beijing Science and Technology Rising Star Program, 400,000 RMB, ongoing.

　　◇ National Natural Science Foundation of China Excellent Young Scientists Fund, 2 million RMB, ongoing.

　　◇ Participated in the National Natural Science Foundation of China Innovative Research Group Project, Chinese Academy of Sciences Strategic Priority Research Program, and National Key R&D Program “Quantum Communication and Quantum Computers.”