Entanglement is one of the most mysterious and fundamental properties of quantum mechanics.
This means that a measurement on one particle will immediately influence the state of the other particles in the entangled system. Most methods for generating entangled states rely on selecting the entangled pairs, for instance, from a large number of other non-entangled particles. Now Chris Monroe of the US National Institute of Standards and Technology in Boulder, Colorado, and co-workers have used this technique to entangle four beryllium ions. Contact us .