The ability to teleport photons through 100 kilometres of free space opens the way for satellite-based quantum communications, say researchers
Teleportation is the extraordinary ability to transfer objects from one location to another without travelling through the intervening space.
The idea is not that the physical object is teleported but the information that describes it. This can then be applied to a similar object in a new location which effectively takes on the new identity.
And it is by no means science fiction. Physicists have been teleporting photons since 1997 and the technique is now standard in optics laboratories all over the world.
The phenomenon that makes this possible is known as quantum entanglement, the deep and mysterious link that occurs when two quantum objects share the same existence and yet are separated in space.
Teleportation turns out to be extremely useful. Because teleported information does not travel through the intervening space, it cannot be secretly accessed by an eavesdropper.
For that reason, teleportation is the enabling technology behind quantum cryptography, a way of sending information with close-to-perfect secrecy.
Unfortunately, entangled photons are fragile objects. They cannot travel further than a kilometre or so down optical fibres because the photons end up interacting with the glass breaking the entanglement. That severely limits quantum cryptography’s usefulness.
However, physicists have had more success teleporting photons through the atmosphere. In 2010, a Chinese team announced that it had teleported single photons over a distance of 16 kilometres. Handy but not exactly Earth-shattering.
Now the same team says it has smashed this record. Juan Yin at the University of Science and Technology of China in Shanghai, and a bunch of mates say they have teleported entangled photons over a distance of 97 kilometres across a lake in China. (cont … MIT Technology Review)