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 February 3, 2009

The Death of Entanglement: Life Without Half-Life

Joseph EberlyAll Natural Processes Follow a Half-Life Rule when Decaying--Except Entanglement

Quantum entanglement, a type of correlation peculiar to quantum objects, has been found to disregard completely the "half-life" rule that is obeyed by all natural processes, such a radioactive decay.

In the current issue of the journal Science, Joseph Eberly, professor of physics at the University of Rochester, with his colleague Ting Yu, reviews four years of investigation into what is now called "the sudden death of entanglement," which they first reported in 2004.

"Our original paper on this triggered an explosion of interest because it attacks an issue that is so fundamental, the natural dying away of physical order," says Eberly. "Entanglement is at the heart of quantum computing, cryptography, teleportation--all these weird effects that physicists are just starting to exploit in labs around the world. And now we have to face that for some reason entanglement doesn't follow the rules."

Eberly and Yu discovered that entanglement--a quantum mechanical phenomenon that exists only when shared--weakens and disappears completely in the face of any common environmental "noise" such as heat or random vibration. In contrast, other known processes under similar circumstances get weaker by half in each successive time interval without ever quite disappearing.

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