Low-loss, high-coherence airbridge interconnects fabricated by single-step lithography

doi:10.1088/1674-1056/ae50e2

Abstract Airbridges are essential for creating high-performance, low-parasitic interconnects in integrated circuits and quantum devices. Conventional multi-step fabrication methods hinder miniaturization and introduce process-related defects. We report a simplified process that enables the fabrication of nanoscale airbridges with just one step of electron-beam lithography. By optimizing a multilayer resist stack with a triple-exposure-dose scheme and a thermal reflow step, we achieve burr-free, suspended metallic bridges with sub-micron features that exhibit robust mechanical stability. Fabricated within a gradiometric SQUID design for superconducting transmon qubits, these airbridges introduce no measurable additional loss in the relaxation time $T_1$, while enabling a 2.5-fold enhancement of the dephasing time $T_2^*$. This efficient method offers a practical route toward integrating high-performance three-dimensional interconnects in advanced quantum and nano-electronic devices.

Keywords: superconducting qubit airbridge fabrication superconducting device

Received: 29 January 2026
Revised: 05 March 2026
Accepted manuscript online: 12 March 2026

PACS:	03.67.Lx	(Quantum computation architectures and implementations)
	81.07.-b	(Nanoscale materials and structures: fabrication and characterization)
	85.25.-j	(Superconducting devices)
	85.25.Am	(Superconducting device characterization, design, and modeling)

Fund: We thank Yang Yang, Xiao-Feng Yi, Ding-Dong Liu, Peng Luo, and Kang-Ding Zhao for technical support in device fabrication and measurements. Project supported by the National Key R&D Program of China (Grant No. 2024YFB4504000) and the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province. Device fabrication was partially performed at the Synergetic Extreme Condition User Facility (SECUF).

Corresponding Authors: Zhao-Hua Yang, Ming-Tang Deng
E-mail: zhaohuayang@quanta.org.cn;mtdeng@nudt.edu.cn

Cite this article:

Ji-Bang Fu(付济邦), Bo Ren(任波), Jian-Dong Ouyang(欧阳剑东), Cong Li(李璁), Ke-Cheng-Qi Zhu(朱可承琪), Yong-Gang Che(车永刚), Xiang Fu(付祥), Shi-Chuan Xue(薛诗川), Zhao-Hua Yang(杨钊华), Ming-Tang Deng(邓明堂), and Jun-Jie Wu(吴俊杰) Low-loss, high-coherence airbridge interconnects fabricated by single-step lithography 2026 Chin. Phys. B 35 040312

[1] Sherwin M E, Simmons J A, Eiles T E, Harff N E and Klem J F 1994 Appl. Phys. Lett. 65 2326
[2] Villeneuve P R, Fan S, Joannopoulos J D, Lim K, Petrich G S, Kolodziejski L A and Reif R 1995 Appl. Phys. Lett. 67 167
[3] Borzenko T, Gould C, Schmidt G and Molenkamp L 2004 Microelectron. Eng. 75 210
[4] Girgis E, Liu J and Benkhedar M L 2006 Appl. Phys. Lett. 88 202103
[5] Chen Z, Megrant A, Kelly J, Barends R, Bochmann J, Chen Y, Chiaro B, Dunsworth A, Jeffrey E, Mutus J Y, O'Malley P J J, Neill C, Roushan P, Sank D, Vainsencher A,Wenner J, White T C, Cleland A N and Martinis J M 2014 Appl. Phys. Lett. 104 052602
[6] Sun Y, Ding J, Xia X, Wang X, Xu J, Song S, Lan D, Zhao J and Yu Y 2022 Appl. Phys. Lett. 121 074001
[7] Stavenga T, Khan S A, Liu Y, Krogstrup P and DiCarlo L 2023 Appl. Phys. Lett. 123 024004
[8] Huang Y H,Wang H, Shen Z, Thomas A, Richardson C J K and Palmer B S 2025 Appl. Phys. Lett. 127 044002
[9] Bolgar A N, Kalacheva D A, Lubsanov V B, Dmitriev A Y, Alekseeva E S, Korostylev E V and Astafiev O V 2025 J. Appl. Phys. 137 154401
[10] Zhang Y, Liu J, Li Y and Yang F 2007 Mater. Sci. Semicond. Process. 10 194
[11] Dunsworth A, Barends R, Chen Y, Chen Z, Chiaro B, Fowler A, Foxen B, Jeffrey E, Kelly J, Klimov P V, Lucero E, Mutus J Y, Neeley M, Neill C, Quintana C, Roushan P, Sank D, Vainsencher A, Wenner J, White T C, Neven H, Martinis J M and Megrant A 2018 Appl. Phys. Lett. 112 063502
[12] Tao H R, Zhang C, Du L, Yang X X, Guo L L, Chen Y, Zhang H F, Jia Z L, Kong W C, Duan P and Guo G P 2024 Appl. Phys. Lett. 125 034001
[13] Bu K, Huai S, Zhang Z, Li D, Li Y, Hu J, Yang X, Dai M, Cai T, Zheng Y C, et al. 2025 npj Quantum Inf. 11 17
[14] Bruckmoser N, Koch L, Tsitsilin I, Grammer M, Bunch D, Richard L, Schirk J, Wallner F, Feigl J, Schneider C M F, Geprägs S, Bader V P, Althammer M, Södergren L and Filipp S 2026 Phys. Rev. Appl. 25 024007
[15] Siddiqi I 2021 Nat. Rev. Mater. 6 875
[16] Mahuli N, Minguzzi J, Gao J, Resnick R, Diez S, Cosmic R, Marcaud G, Hunt M, Swenson L, Rose J, Painter O and Jarrige I 2025 ACS Nano 19 41136
[17] Janzen N, Kononenko M, Ren S and Lupascu A 2022 Appl. Phys. Lett. 121 094001
[18] Jin Y, Moreno M, T Vianez P M, TanWK, Griffiths J P, Farrer I, Ritchie D A and Ford C J B 2021 Appl. Phys. Lett. 118 162108
[19] Fu J B, Wang D W, Ren B, Yang Z H, Hu S, Huang G Y, Cao S H, Liu D D, Zhang X F, Fu X, Xue S C, Che Y G, Liu Y, Deng M T and Wu J J 2026 arXiv:2601.02137 [quant-ph]
[20] Wu Y, BaoWS, Cao S, Chen F, Chen M C, Chen X, Chung T H, Deng H, Du Y, Fan D, Gong M, et al. 2021 Phys. Rev. Lett. 127 180501
[21] Shi Y H, Liu Y, Zhang Y R, Xiang Z, Huang K, Liu T, Wang Y Y, Zhang J C, Deng C L, Liang G H, Mei Z Y, Li H, Li T M, Ma W G, Liu H T, Chen C T, Liu T, Tian Y, Song X, Zhao S P, Xu K, Zheng D, Nori F and Fan H 2023 Phys. Rev. Lett. 131 080401
[22] Xiang Z C, Huang K, Zhang Y R, Liu T, Shi Y H, Deng C L, Liu T, Li H, Liang G H, Mei Z Y, et al. 2023 Nat. Commun. 14 5433
[23] Wu Z H, Lei L X, Zhang X F, Xue S C, Hu S, Li C, Fu X, Chen P X, Lu K, Deng M T and Wu J J 2025 Chin. Phys. Lett. 42 040501

[1]	Generation of cross-cross resonance gates with two fluxonium qubits Xinpeng Chen(陈鑫鹏) and Zeliang Xiang(项泽亮). Chin. Phys. B, 2026, 35(4): 040308.
[2]	A low-noise and high-stability DC source for superconducting quantum circuits Daxiong Sun(孙大雄), Jiawei Zhang(张家蔚), Peisheng Huang(黄培生), Yubin Zhang(张玉斌), Zechen Guo(郭泽臣), Tingjin Chen(陈庭槿), Rui Wang(王睿), Xuandong Sun(孙炫东), Jiajian Zhang(张家健), Wenhui Huang(黄文辉), Jiawei Qiu(邱嘉威), Ji Chu(储继), Ziyu Tao(陶子予), Weijie Guo(郭伟杰), Xiayu Linpeng(林彭夏雨), Ji Jiang(蒋骥), Jingjing Niu(牛晶晶), Youpeng Zhong(钟有鹏), and Dapeng Yu(俞大鹏). Chin. Phys. B, 2025, 34(9): 090303.
[3]	All-microwave CZ gate based on fixed-frequency driven coupler Wanpeng Gao(高万鹏), Xiaoliang He(何潇梁), Zhengqi Niu(牛铮琦), Daqiang Bao(包大强), Kuang Liu(刘匡), Junfeng Chen(陈俊锋), Zhen Wang(王镇), and Z. R. Lin(林志荣). Chin. Phys. B, 2025, 34(4): 040304.
[4]	M²CS: A microwave measurement and control system for large-scale superconducting quantum processors Jiawei Zhang(张家蔚), Xuandong Sun(孙炫东), Zechen Guo(郭泽臣), Yuefeng Yuan(袁跃峰), Yubin Zhang(张玉斌), Ji Chu(储继), Wenhui Huang(黄文辉), Yongqi Liang(梁咏棋), Jiawei Qiu(邱嘉威), Daxiong Sun(孙大雄), Ziyu Tao(陶子予), Jiajian Zhang(张家健), Weijie Guo(郭伟杰), Ji Jiang(蒋骥), Xiayu Linpeng(林彭夏雨), Yang Liu(刘阳), Wenhui Ren(任文慧), Jingjing Niu(牛晶晶), Youpeng Zhong(钟有鹏), and Dapeng Yu(俞大鹏). Chin. Phys. B, 2024, 33(12): 120309.
[5]	Diagnosing quantum crosstalk in superconducting quantum chips by using out-of-time-order correlators Yujia Zhang(张宇佳), Yu Zhang(张钰), Shaoxiong Li(李邵雄), Wen Zheng(郑文), and Yang Yu(于扬). Chin. Phys. B, 2024, 33(11): 110306.
[6]	Calibration and cancellation of microwave crosstalk in superconducting circuits Haisheng Yan(严海生), Shoukuan Zhao(赵寿宽), Zhongcheng Xiang(相忠诚), Ziting Wang(王子婷), Zhaohua Yang(杨钊华), Kai Xu(许凯), Ye Tian(田野), Haifeng Yu(于海峰), Dongning Zheng(郑东宁), Heng Fan(范桁), and Shiping Zhao(赵士平). Chin. Phys. B, 2023, 32(9): 094203.
[7]	Entanglement properties of superconducting qubits coupled to a semi-infinite transmission line Yang-Qing Guo(郭羊青), Ping-Xing Chen(陈平形), and Jian Li(李剑). Chin. Phys. B, 2023, 32(6): 060302.
[8]	Demonstrate chiral spin currents with nontrivial interactions in superconducting quantum circuit Xiang-Min Yu(喻祥敏), Xiang Deng(邓翔), Jian-Wen Xu(徐建文), Wen Zheng(郑文), Dong Lan(兰栋), Jie Zhao(赵杰), Xinsheng Tan(谭新生), Shao-Xiong Li(李邵雄), and Yang Yu(于扬). Chin. Phys. B, 2023, 32(4): 047104.
[9]	Single-flux-quantum-based qubit control with tunable driving strength Kuang Liu(刘匡), Yifan Wang(王一凡), Bo Ji(季波), Wanpeng Gao(高万鹏), Zhirong Lin(林志荣), and Zhen Wang(王镇). Chin. Phys. B, 2023, 32(12): 128501.
[10]	Realization of high-fidelity and robust geometric gates with time-optimal control technique in superconducting quantum circuit Zhimin Wang(王治旻), Zhuang Ma(马壮), Xiangmin Yu(喻祥敏), Wen Zheng(郑文), Kun Zhou(周坤), Yujia Zhang(张宇佳), Yu Zhang(张钰), Dong Lan(兰栋), Jie Zhao(赵杰), Xinsheng Tan(谭新生), Shaoxiong Li(李邵雄), and Yang Yu(于扬). Chin. Phys. B, 2023, 32(10): 100304.
[11]	Variational quantum simulation of thermal statistical states on a superconducting quantum processer Xue-Yi Guo(郭学仪), Shang-Shu Li(李尚书), Xiao Xiao(效骁), Zhong-Cheng Xiang(相忠诚), Zi-Yong Ge(葛自勇), He-Kang Li(李贺康), Peng-Tao Song(宋鹏涛), Yi Peng(彭益), Zhan Wang(王战), Kai Xu(许凯), Pan Zhang(张潘), Lei Wang(王磊), Dong-Ning Zheng(郑东宁), and Heng Fan(范桁). Chin. Phys. B, 2023, 32(1): 010307.
[12]	Measuring Loschmidt echo via Floquet engineering in superconducting circuits Shou-Kuan Zhao(赵寿宽), Zi-Yong Ge(葛自勇), Zhong-Cheng Xiang(相忠诚), Guang-Ming Xue(薛光明), Hai-Sheng Yan(严海生), Zi-Ting Wang(王子婷), Zhan Wang(王战), Hui-Kai Xu(徐晖凯), Fei-Fan Su(宿非凡), Zhao-Hua Yang(杨钊华), He Zhang(张贺), Yu-Ran Zhang(张煜然), Xue-Yi Guo(郭学仪), Kai Xu(许凯), Ye Tian(田野), Hai-Feng Yu(于海峰), Dong-Ning Zheng(郑东宁), Heng Fan(范桁), and Shi-Ping Zhao(赵士平). Chin. Phys. B, 2022, 31(3): 030307.
[13]	Shortcut-based quantum gates on superconducting qubits in circuit QED Zheng-Yin Zhao(赵正印), Run-Ying Yan(闫润瑛), and Zhi-Bo Feng(冯志波). Chin. Phys. B, 2021, 30(8): 088501.
[14]	Quantum computation and simulation with superconducting qubits Kaiyong He(何楷泳), Xiao Geng(耿霄), Rutian Huang(黄汝田), Jianshe Liu(刘建设), and Wei Chen(陈炜). Chin. Phys. B, 2021, 30(8): 080304.
[15]	Universal quantum control based on parametric modulation in superconducting circuits Dan-Yu Li(李丹宇), Ji Chu(储继), Wen Zheng(郑文), Dong Lan(兰栋), Jie Zhao(赵杰), Shao-Xiong Li(李邵雄), Xin-Sheng Tan(谭新生), and Yang Yu(于扬). Chin. Phys. B, 2021, 30(7): 070308.

No Suggested Reading articles found!

Viewed

Full text

Abstract

Cited

Metrics
Related Articles

Low-loss, high-coherence airbridge interconnects fabricated by single-step lithography

Cite this article:

Online attention