The quantum link called entanglement keeps getting longer—in the latest demonstration, the distance spanned two of Spain's Canary Islands. When two photons are entangled, what happens to one instantaneously determines the fate of the other, no matter how far apart they are. Using a laser, Anton Zeilinger of the University of Vienna and his team created entangled pairs of photons on the island of La Palma and then fired one member of each pair to a telescope on Tenerife, 144 kilometers away. That distance is 10 times farther than entangled photons have ever flown through the air. Such photons might prove suitable for sending scrambled messages that cannot be decoded or secretly read. The team discussed its feat at the March meeting of the American Physical Society.
This article was originally published with the title "Spooky Action at a Greater Distance" in Scientific American 296, 5, 36 (May 2007)