  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 SI system around quantum effects and is used in scores of
quantum devices. By itself, the use of Josephson junctions in the 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.
