In superconducting quantum circuits, airbridges are critical for eliminating parasitic slotline modes of coplanar waveguide circuits and reducing crosstalks between direct current magnetic flux biases. Here, we present a technique for fabricating superconducting airbridges. With this technique, a single layer of photoresist is employed, and the gradient exposure process is used to define the profile of airbridges. In order to properly obtain the bridge profile, we design exposure dosage based on residual photoresist thickness and laser power calibrations. Compared with other airbridge fabrication techniques, the gradient exposure fabrication technique provides the ability to produce lossless superconducting airbridges with flexible size and, thus, is more suitable for large-scale superconducting quantum circuits. Furthermore, this method reduces the complexity of the fabrication process and provides a high fabrication yield.
@article{arxiv.2506.14565,
title = {Fabrication of airbridges with gradient exposure},
author = {Yuting Sun and Jiayu Ding and Xiaoyu Xia and Xiaohan Wang and Jianwen Xu and Shuqing Song and Dong Lan and Jie Zhao and Yang Yu},
journal= {arXiv preprint arXiv:2506.14565},
year = {2025}
}