Thursday, January 29, 2009

Quantum teleportation - Joint Quantum Institute Maryland university


Scientists have come a bit closer to achieving the "Star Trek" feat of teleportation. No one is galaxy-hopping, or even beaming people around, but for the first time, information has been teleported between two separate atoms across a distance of a meter — about a yard.
This is a significant milestone in a field known as quantum information processing, said Christopher Monroe of the Joint Quantum Institute at the University of Maryland, who led the effort.
Teleportation is one of nature's most mysterious forms of transport: Quantum information, such as the spin of a particle or the polarization of a photon, is transferred from one place to another, without traveling through any physical medium. It has previously been achieved between photons (a unit, or quantum, of electromagnetic radiation, such as light) over very large distances, between photons and ensembles of atoms, and between two nearby atoms through the intermediary action of a third.
None of those, however, provides a feasible means of holding and managing quantum information over long distances.
Now the JQI team, along with colleagues at the University of Michigan, has succeeded in teleporting a quantum state directly from one atom to another over a meter. That capability is necessary for workable quantum information systems because they will require memory storage at both the sending and receiving ends of the transmission.
In the Jan. 23 issue of the journal Science, the scientists report that, by using their protocol, atom-to-atom teleported information can be recovered with perfect accuracy about 90 percent of the time — and that figure can be improved.
"Our system has the potential to form the basis for a large-scale 'quantum repeater' that can network quantum memories over vast distances," Monroe said. "Moreover, our methods can be used in conjunction with quantum bit operations to create a key component needed for quantum computation."


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