Quantum snare entraps key fifth photon

In a new feat of quantum-scale manipulation, physicists have joined five photons in a condition of mutually linked properties called entanglement.

Jian-Wei Pan of the University of Science and Technology of China in Hefei and his colleagues achieved this complex state by firing an intense laser beam into a collection of crystals, mirrors, and detectors.

Five is a magic number in this context because entanglement of that many or more photons or other particles would enable a future quantum computer to find and eliminate random errors in its data, Pan says. Five-particle entanglement also makes possible a previously unrealizable scheme for transferring quantum data—which can have odd characteristics, such as representing several numbers at once.

So far, physicists have used only pairs of entangled particles, including photons, to transfer quantum information between locations, a technique known as quantum teleportation (SN: 6/19/04, p.387: Teleporting Matter’s Traits: Beaming information quantum-style).

In such entanglements, a property of the particles, say, their electromagnetic fields’ orientation in space, become correlated. For instance, if one of the particle’s field orientations is found to be horizontal, then that of another particle might have to be vertical.

With five-particle entanglement, the options for teleporting increase. Not only are there more choices for the destination of information, but the system can even build a delay into the transfer, which could prove useful for decisions about routing information, Pan and his colleagues report in the July 1 Nature.

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