Quantum staircase effect seen in ultracold atomic junction

Berlin, Germany (SPX) Dec 26, 2025
Scientists have observed Shapiro steps, a staircase-like quantum effect, in a system of ultracold atoms driven by an alternating current across an atomic Josephson junction formed by atoms cooled near absolute zero and separated by a thin laser-light barrier. In the experiment, the atoms collectively crossed the laser barrier without energy loss, as if it were transparent, through quantum