The Josephson effect in scanning tunneling microscopy (STM) is an excellent tool to probe the properties of a superconductor on a local scale. We use atomic manipulation in a low temperature STM to create mesoscopic single channel contacts and study the Josephson effect at arbitrary transmissions. We observe significant deviations from the Ambegaokar-Baratoff formula relating the critical current to the order parameter starting from transmissions of τ > 0.1. Using the full current-phase relation, we model the Josephson effect in the dynamical Coulomb blockade regime, where the charging energy of the junction capacitance cannot be neglected, and find excellent agreement with the experimental data. Projecting the current-phase relation onto the charge transfer operator shows that at high transmission, non-linear behaviour arises and multiple Cooper pair tunneling may occur. Our model includes these deviations, which become non-negligible in Josephson-STM, for example, when scanning across single adatoms.

扫描隧道显微镜（STM）中的约瑟夫森效应是在局部范围内探测超导体性能的出色工具。我们在低温STM中使用原子操纵来创建介观的单通道接触，并研究任意传输下的约瑟夫森效应。我们观察到与Ambegaokar-Baratoff公式的显着偏差，该公式将临界电流与从τ传输开始的阶跃参数相关 > 0.1。利用全电流-相位关系，我们在动态库仑阻塞状态下建立了约瑟夫森效应，其中结电容的充电能量不能忽略，并且与实验数据非常吻合。将电流-相位关系投影到电荷转移算子上表明，在高传输率下，会出现非线性行为，并且可能会发生多个库珀对隧穿。我们的模型包括这些偏差，例如，在单个原子上进行扫描时，这些偏差在Josephson-STM中变得不可忽略。