An optical curve ball
When a football is kicked with spin, it curves through the air. This phenomenon, familiar to football fans, is known to physicists as the Magnus effect. Surprisingly, an atom interacting with a tightly focused laser beam shows a similar effect: the atom behaves like the ball, and the laser light replaces the air that the ball interacts with. The strongest interaction between the atom and the laser occurs slightly away from where the laser itself is centred.
While this optical analog of the Magnus effect was predicted several years ago by UvA scientist Robert Spreeuw [1], it had so far not been experimentally observed. Still, the effect is relevant for atomic physics experiments, where tightly focused laser beams, or optical tweezers, are used to precisely control atoms for quantum computing. In this context, the optical Magnus effect could be a cause of qubit decoherence, the loss of information stored in quantum bits due to their interaction with the environment. At the same time, this ‘bug’ could be turned into a feature: utilizing the optical Magnus effects opens the door for new ways of manipulating qubits [2].