Two teams improve long-distance transmission of information about particles
Quantum information has leapt through the air about 100 kilometers or more in two new experiments, farther and with greater fidelity than ever before. The research brings truly long-distance quantum communication networks, in which satellites could beam encrypted information around the globe, closer to reality.
Both studies involve quantum teleportation, which transports the quantum state of one particle onto another. This Star Trek–like feat is possible because of a phenomenon called entanglement, in which pairs of particles become linked in such a way that measuring a certain property of one instantly determines the same property for the other, even if separated by large distances.
In teleportation, two people — physicists call them Alice and Bob — share one each of a pair of entangled particles. Alice measures a property on her particle and sends Bob a note, through regular channels, about what she did. Bob then knows how to alter his own