Superconducting circuits, which have zero electrical resistance, could enable the development of electronic components that are significantly more energy-efficient than most chips used today. Importantly, superconducting circuits rely on an electronic element known as the Josephson junction, which allows them to manipulate quantum information and mediate photon interactions. While past studies have tried to enhance the performance and coherence of Josephson circuits, so far, the most promising results in terms of photon lifetimes were achieved in microwave cavities.
Source:
https://phys.org/news/2019-12-quantum-oscillator-josephson-circuit.html