summarizing the study. Credit: K.-I. Ellers/University of California, Berkeley. Harnessing the Quantum Precision of Superfluid Helium The proposed device centers on the use of helium-4, which transitions into a superfluid state when cooled below 2.17...

into a narrow stream. The PSI team overcame this by introducing positive muons into a layer of isotopically purified superfluid helium cooled to 0.2 kelvin. As the muons came to rest within the liquid, they captured electrons to form muonium. Due to the...