The Canary Islands of La Palma and Tenerife have been briefly connected by a quantum teleportation system that sets a new distance record for the spooky communications technique.
In an angle that will get Trekkie bloggers reaching for the “beam me up” metaphors, the researchers, from Austria, Germany, Canada and Norway, hope that quantum teleportation could one day be used for ground-to-satellite communications.
In quantum teleportation, the phenomenon known as “entanglement” to transmit information instantaneously. As long as entanglement isn’t destroyed, the state of one particles – in this case, photons – will reflect changes to the state of the other, regardless of distance (one of the characteristics of quantum physics that troubled Albert Einsten).
The long-distance teleportation setup.
The 143-km teleportation involves three photons. Alice (in La Palma) generates an entangled pair of photons, and sends one over a non-quantum channel (a fibre) to Bob (in Tenerife). The teleportation photon (generated by a third party, Charlie, in La Palma) is provided to Alice, and when its state is projected onto Alice’s photon, Bob is able to measure its state at the far end of the link.
In the Canary Islands experiment, submitted to Arxiv, entanglement was also used to synchronise time between the two ends of the channel.
An extra wrinkle in the experiment was that one of the photons was sent through the atmosphere – an important technical step, since the experimenters hope to establish that quantum teleportation can be used to communicate with satellites. It is, however, very difficult to preserve quantum states while sending a photon through 143 km of air, water vapour, clouds and the like.
As the paper notes, “the severe environmental conditions imposed demanding requirements onto the whole long-distance teleportation setup: link attenuation fluctuations due to atmospheric turbulence, induced by the harsh meteorological situations including rapid temperature change, sand storms, rain, fog, strong wind and even snow”. The weather, they note, delayed the experiment for a year.
The new distance record for quantum teleportation eclipses an earlier experiment in which researchers from the University of Science and Technology in China at Shanghai teleported entangled photons across 97 km. ®