Post by Kessie on Jan 8, 2012 13:31:34 GMT -5
A group of researchers report in the December 2 issue of Science that they managed to entangle the quantum states of two diamonds separated by 15 centimeters. Quantum entanglement is a phenomenon by which two or more objects share an unseen link bridging the space between them—a hypothetical pair of entangled dice, for instance, would always land on matching numbers, even if they were rolled in different places simultaneously.
But that link is fragile, and it can be disrupted by any number of outside influences. For that reason entanglement experiments on physical systems usually take place in highly controlled laboratory setups—entangling, say, a pair of isolated atoms cooled to nearly absolute zero.
In the new study, researchers from the University of Oxford, the National Research Council of Canada and the National University of Singapore (NUS) showed that entanglement can also be achieved in macroscopic objects at room temperature. "What we have done is demonstrate that it's possible with more standard, everyday objects—if diamond can be considered an everyday object," says study co-author Ian Walmsley, an experimental physicist at Oxford. "It's possible to put them into these quantum states that you often associate with these engineered objects, if you like—these closely managed objects."
...
Walmsley and his colleagues set up an experiment that would attempt to entangle two different diamonds using phonons. They used two squares of synthetically produced diamond, each three millimeters across. A laser pulse, bisected by a beam splitter, passes through the diamonds; any photons that scatter off of the diamond to generate a phonon are funneled into a photon detector. One such photon reaching the detector signals the presence of a phonon in the diamonds.
But because of the experimental design, there is no way of knowing which diamond is vibrating. "We know that somewhere in that apparatus, there is one phonon," Walmsley says. "But we cannot tell, even in principle, whether that came from the left-hand diamond or the right-hand diamond." In quantum-mechanical terms, in fact, the phonon is not confined to either diamond. Instead the two diamonds enter an entangled state in which they share one phonon between them.
Read more:
www.scientificamerican.com/article.cfm?id=room-temperature-entanglement
