Twisting light to trap atoms

Scientists are now exploiting orbital angular momentum in various experiments. Orbital angular momentum can arise if phase fronts, such as wave crests, become twisted around the direction of light propagation. Since the phenomenon was confirmed in 1992, researchers have investigated it in many experiments, initially with classical techniques but increasingly on the quantum level. Areas where orbital angular momentum can be used include in optical tweezers to rotate small particles; it can also be transferred from light to ultracold molecules, and it can be used as a model for applications in quantum cryptography.