Unite to build a quantum internet

Just over 20 years ago, physicists [1] discovered a way of ‘teleporting’ a quantum system from one place to another without moving it. There are physical limits: nothing can be transmitted faster than the speed of light; and the uncertainty principle restricts what we can know about a quantum system’s state at a given time. Nonetheless the replica can perfectly mimic the original thanks to the weirdest feature of quantum mechanics – entanglement, which Einstein described as “spooky action at a distance”. This is the property of quantum systems to become intimately correlated with each other so that an action on one has an instantaneous `effect' on the other, even for systems too far apart to interact.