Teleportation Of Information

The development of quantum computing seems firmly on the way, now that information has been teleported about a meter. Christopher Monroe, of the University of Maryland's Joint Quantum Institute, spoke of this achievement as a milestone in quantum information processing.

The type of information involved — now transferable without going through any physical medium — can be the spin of a sub-atomic particle or even a photon's polarization.

Prior to this, teleportation had been achieved between photons over distances, between photons and atom ensembles, and between two atoms by means of the intermediary action of a third atom. But none had made use of effective methods of managing quantum information over a distance.

Now, the Joint Quantum Institute team, with the help of University of Michigan colleagues, have teleported a quantum state from one atom to another. The basis of their process works because two particles can become "entangled," where they become one entity (describable in a single equation) — and any change to one is a change to the other, even if at a distance.

In a new hybrid approach, light is utilized for transferral of quantum information between atoms.

In the January 23, 2009 Science journal, the JQI scientists mentioned that information teleported from atom to atom could be accurately recovered 90 percent of the time by using their protocol. Thus it could possibly provide a basis for future quantum repeaters helping the networking of quantum memories over great distances. At this point, their experiments have far to go, since the success rate is still very low. But developments appear promising. The paper describes that the "scheme may be used for scalable quantum computation and quantum communication."

In the described process, both ytterbium ions are initialized in a particular ground state. (An ion is an atom that has gained or lost electrons.) The first ion gets irradiated by a tailored microwave burst. Then both ions are excited by a laser pulse of a duration of one trillionth of a second. The set-up used to accomplish this is an odd combination of semitransparent beam splitters, fiber optics, lasers, and vacuum chambers. The result qualifies as teleportation because the information vanishes during measurement of the ion at the first point (in a way that does not reveal the information) and reappears when a microwave pulse is applied to the ion at the second point.

— Douglas Chapman

Sources:

New York Times, NYTimes.com, http://www.nytimes.com/2009/02/03/science/03teleportation.html, 2/3/09

Fox News, http://www.foxnews.com/story/0,2933,482264,00.html, 1/28/09

Joint Quantum Institute: Christopher R. Monroe, http://jqi.umd.edu/people/UMfellows/monroe.html

Science, 23 January 2009, Vol. 323, no. 5913, pp. 486-489, http://www.sciencemag.org/cgi/content/abstract/323/5913/486

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