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

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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

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