Spooky Quantum Entanglement Disturbed

Clara Moskowitz LiveScience Senior Writer LiveScience.com Physicists have long been puzzled over a mystical nexus between particles called entanglement - and now they've established this bizarre connection in a new experiment. When two or more particles are entangled, they hold a connection even if separated across an entire galaxy.

If an activity is performed on one particle, its linked partner will also respond. Amazingly, entanglement has really been proved to occur, though lab tests haven't established it out to anything like galactic distances, yet. (When Albert Einstein's calculations suggested the theoretical possibility of entanglement, he was so alarmed he dubbed it "spooky action at a distance.") In a recent study, a research team entangled four particles together under disturbing conditions to see whether they would observe that link or break loose. Probing entanglement like this will not just provide scientists with more info around the freaky ways our public works, but also assist them understand behavior of entangled particles as ingredients for superfast quantum computers. In the new study, researchers entangled four calcium ions (atoms with one missing electron, leaving them positively charged). They did this by exposing the ions to specially calibrated laser light while the ions were moving in a special pattern. The light imparts a small fire of vitality to the ions, causing their electrons to start from one energy level to the next, leaving all the atoms in a matching entangled state. Then the entangled particles were open to a "noisy" environment, where laser light was present that could potentially disturb their connections. "We found that as you introduce noise there is a place where you can even have entanglement, but noise interferes with the useful properties of entanglement," said lead author Julio Barreiro of the Plant of Experimental Physics of the University of Innsbruck in Austria. "The environment causes these correlations to decay." This is useful knowledge for designing quantum computers, he said, because such laser noise would probably be present. "This is relevant because for many calculations that rely on entanglement, they rely on it being robust against noise," Barreiro told LiveScience. "But there are other approaches that will avoid these problems. There are other ways of programming a quantum computer that do it immune to sources of noise." Given recent advances in entanglement science, Barreiro said it may be as small as 10 or 20 days before scientists can produce a functional quantum computer able to serve many times more information at significantly faster speeds than normal computers. "Right now for instance we are building one that will factorize 15 - 3 times 5," he said. "That's how basic we are. But of course if you try you can do this in a scalable system, then it can be lengthened to larger numbers." The researchers reported their findings online in the journal Nature Physics.