Gate-Tunable Critical Current of the Three-Dimensional Niobium Nanobridge Josephson Junction.

Yu, Shujie; Chen, Lei; Pan, Yinping; Wang, Yue; Zhang, Denghui; Wu, Guangting; Fan, Xinxin; Liu, Xiaoyu et al. · Nano Lett · 2023

basic_science · Level V

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Abstract

Recent studies have shown that the critical currents of several metallic superconducting nanowires and Dayem bridges can be locally tuned by using a gate voltage (<i>V</i><sub>g</sub>). Here, we report a gate-tunable Josephson junction structure constructed from a three-dimensional (3D) niobium nanobridge junction (NBJ) with a voltage gate on top. Measurements up to 6 K showed that the critical current of this structure can be tuned to zero by increasing <i>V</i><sub>g</sub>. The critical gate voltage was reduced to 16 V and may possibly be reduced further by reducing the thickness of the insulation layer between the gate and the NBJ. Furthermore, the flux modulation generated by Josephson interference of two parallel 3D NBJs can also be tuned by using <i>V</i><sub>g</sub> in a similar manner. Therefore, we believe that this gate-tunable Josephson junction structure is promising for superconducting circuit fabrication at high integration levels.