Laser beam teleportation

An Australian-French-German team of physicists has carried out a new experiment of so-called ‘quantum teleportation’. This time, it was not a bunch of photons, but an entire laser beam that was teleported.


Quantum teleportation is becoming almost common in laboratories. Many experiments have already proven true the ‘non-locality’ of quantum mechanics. That is to say that in some circumstances, an action on a particle can influence instantly another particle located far away. Most of these experiments have been carried out with photons, but in principle this effect is also observable with other particles. It will never be said enough: the quantum teleportation has not much to do with Star Trek teleportation. In these experiments, it is not the photons themselves that are teleported, but their properties. Two photons emitted in some specific process are ‘entangled’, that is to say that they are bound in such a way that modifications of the properties of one of them influence instantly the properties of the other one, no matter the distance these photons are apart. Nevertheless the laws relativity are not violated. Why? Because no observable transport of information has occurred in the process. The changes of the photon properties can only be established a posteriori by the use of classical means of transportation.


For the first time, Ping Koy Lam’s team at the Australian National University in Canberra carried out such an experiment with a laser beam. This means that billions of photons were teleported through the laboratory. The initial laser was destroyed in the process, as always in these experiments, and reconstructed one metre away with exactly the same properties. The next step would be to teleport atoms, like a Danish team has shown it theoretically possible in 2001.


Even so, teleportation of macroscopic objects involves billions of billions of billions atoms and thus presents technical difficulties that could very well never been solved. Moreover, this is not a ‘real’ teleportation, but the destruction of an object, and its reconstruction at another location, which is not acceptable for human being teleportation.


In the mean time, quantum teleportation should allow 100% secure encryption techniques (the US army is already working on it) and much faster computers…


Fabrice, Science Team
June 2002

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