A surprising twist in the quantum world Villigen, 27.08.2026 — Researchers at the Paul Scherrer Institute PSI, ETH Zurich and the University of Amsterdam have directly observed the optical Magnus effect for the first time. This phenomenon is the optical counterpart of an effect from classical mechanics. It is relevant to quantum computing because it can influence the precise control of qubits, the fundamental units of quantum information. Table tennis professionals are true masters at redirecting fast-moving projectiles. Putting a targeted spin on a serve can make the little white ball fly straight towards the edge of the table but then, at the last moment, take a sharp curve into the left corner. The physical phenomenon behind this sporting trick is known as the Magnus effect. It acts on balls of all sizes and has helped decide more than a few football matches. An international research collaboration at the Paul Scherrer Institute PSI has now taken the leap from ball to atom, experimentally demonstrating the so-called optical Magnus effect for the first time. In this case, however, there is no atom flying along a curved trajectory. Instead, the researchers direct a tightly focused laser beam at a single ion and observe the resulting interaction. With this they were able to show that the point of maximum interaction is shifted sideways – an important finding for the development of quantum computers in which laser light is used to precisely control qubits. The researchers report their findings in the journal Physical Review Letters. When the centre is suddenly off-centre With a tightly focused laser beam directed at an ion, one would expect the strongest interaction to occur where the laser beam is most intense: at its centre. However, tightly focusing the laser also changes the spatial structure of its electromagnetic field. As