Ultracold Atoms Mimic Quantum Circuit, Proving Universal Physics

A team in Germany recreated a Josephson junction – a fundamental quantum circuit element – using ultracold atoms and lasers, revealing that atoms can behave just like electrons in a superconductor. In this experiment, two Bose–Einstein condensates were separated by a thin, vibrating laser barrier to mimic the junction. Remarkably, the system displayed Shapiro steps – fixed voltage plateaus that normally appear in superconducting circuits – now observed in an atomic gas. This marks the first visualization of these quantum effects in a completely different medium, affirming that the underlying physics is universal. “The fact that this effect now appears in a completely different system…confirms [that] Shapiro steps are a universal phenomenon,” said Prof. Herwig Ott, senior author. The work, published in Science, showcases the power of quantum simulation – using one controllable quantum system to study another. It not only provides a new way to probe elusive superconducting phenomena, but also pioneers the field of “atomtronics,” where atomic flows in engineered circuits could emulate electronic devices. The researchers plan to connect multiple atomic junctions into complete atom-based circuits, potentially opening a novel platform to test quantum technologies and study coherent matter waves in real time This cross-disciplinary breakthrough bridges the gap between electron-based and atom-based quantum tech, bringing fresh insight into quantum coherence and universality