Half a century after its discovery, the Josephson junction has become the most important nonlinear quantum electronic component at our disposal. It has helped reshape the International System of Units around quantum effects and is used in scores of quantum devices. By itself, the use of Josephson junctions in volt metrology seems to imply an exquisite understanding of the component in every aspect. Yet, surprisingly, there have been long-standing subtle issues regarding the modeling of the interaction of a junction with its electromagnetic environment. Here, we find that a Josephson junction connected to a resistor does not become insulating beyond a given value of the resistance due to a dissipative quantum phase transition, as is commonly believed. Our work clarifies how this key quantum component behaves in the presence of a dissipative environment and provides a comprehensive and consistent picture, notably regarding the treatment of its phase.

中文翻译：

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约瑟夫逊结中无耗散量子相变

发现约瑟夫森结后半个世纪，它已成为我们可以使用的最重要的非线性量子电子组件。它帮助重塑了围绕量子效应的国际单位制，并被用于多种量子设备中。就其本身而言，在伏特计量学中使用约瑟夫森结似乎意味着对各个方面的组件都有精湛的理解。然而，令人惊讶的是，关于结与其电磁环境的相互作用的建模一直存在着细微的长期问题。在这里，我们发现，通常认为，由于耗散量子相变，连接到电阻器的约瑟夫逊结不会由于给定电阻值而变得绝缘。