Oct 19, 2006

Entanglement

Posted in Physics, Science at 12:00 am by David Bradley -- Click to comment

NIST physicists have taken a step towards making entanglement, the quantum phenomenon Einstein referred to as “spooky action at a distance” - into a practical tool.

The team demonstrated a method for refining entangled atom pairs (a process called purification) so they might be used in quantum computers, communications systems with potentially “unbreakable” data encryption, and highly accurate atomic clocks.

The research reported in today’s issue of Nature marks the first time atoms have been both entangled and subsequently purified. This had only been done before with entangled photons. The new experiment entangles two pairs of atoms but measures only one pair.

According to NASA, Einstein never liked entanglement as it seemed to run counter to the central tenet of his theory of relativity that nothing, not even information, could travel faster than the speed of light. Because it is possible to prepare two particles in a single quantum state so that when one is particle is observed, the other will be observed simultaneously to be in the complimentary state and vice versa. As a result, measurements performed on one system seem to be instantaneously influencing other systems with which it is entangled.

However, although two entangled systems appear to interact even though they are separated no useful “information” can be transmitted in this way, which means causality is not compromised and Einstein’s theory remains intact.

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