An international team including the University of Florence observes Shapiro steps in ultra-cold atomic circuits for the first time In a major advance for quantum science, an international team of researchers has achieved the first-ever observation of Shapiro steps in ultracold atoms. This milestone offers a new window into quantum mechanics in real time and lays the groundwork for advanced quantum sensors and quantum simulation.The findings highlight how quantum effects at the microscopic level can influence and be harnessed in large-scale systems - an idea at the core of the 2025 Nobel Prize in Physics.Two experimental teams, one from LENS, CNR-INO, the University of Florence and the UNAM in Mexico and one from the RPTU University Kaiserslautern-Landau have observed Shapiro steps in ultracold quantum gases, following the protocol developed at the Technology Innovation Institute (TII) in Abu Dhabi, the University of Hamburg and the University of Catania. Their findings could form the foundation for next-generation quantum sensors. These devices provide proof-of-concept for pressure standards, with the potential to outperform the existing technologies.The findings were published in two ‘back-to-back’ articles in Science, an editorial format reserved by the journal for results considered particularly significant.In conventional electronics, Josephson junctions allow supercurrents to pass with zero resistance - an essential mechanism in quantum computing and sensing. But until now, the quantum phenomenon known as Shapiro steps, quantized responses that occur when the system is driven by an external oscillation, had only been observed in superconducting circuits.By recreating this effect with ultracold atoms, scientists can now slow down and magnify the inner workings of quantum systems, making the invisible visible.In the experiments, one led by Dr. Giacomo Roati of LENS and CNR-INO's research group in Sesto Fiorentino, and one led by Professor Herwig Ott at the RPTU University Kaiserslautern-Landau, each oscillation of the system generated precise numbers of miniature whirlpools, called vortex–antivortex pairs, or vortex rings. These were responsible for producing the step-like signals observed.“Using ultracold atoms is like watching quantum mechanics in slow motion,” said Dr. Giulia Del Pace, first author of the Florence experiment. Source: Press Office of the Consiglio Nazionale delle RicercheImage by Giulia Del PaceMore information about the findings can be read on Science Science: Shapiro steps in strongly-interacting Fermi gases Science: Observation of Shapiro steps in an ultracold atomic Josephson junction Published on: December 16th, 2025