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Researchers propose using distant quasars to test Bell's theorem
http://phys.org/news/2014-02-distant-quasars-bell-theorem.html
Researchers propose using distant quasars to test Bell's theorem
Feb 20, 2014 by Jennifer Chu
In a paper published this week in the journal Physical Review Letters, MIT researchers propose an experiment that may close the last major loophole of Bell's inequality—a 50-year-old theorem that, if violated by experiments, would mean that our universe is based not on the textbook laws of classical physics, but on the less-tangible probabilities of quantum mechanics.
<snip>
Though two major loopholes have since been closed, a third remains; physicists refer to it as "setting independence," or more provocatively, "free will." This loophole proposes that a particle detector's settings may "conspire" with events in the shared causal past of the detectors themselves to determine which properties of the particle to measure—a scenario that, however far-fetched, implies that a physicist running the experiment does not have complete free will in choosing each detector's setting. Such a scenario would result in biased measurements, suggesting that two particles are correlated more than they actually are, and giving more weight to quantum mechanics than classical physics.
<snip>
The idea, essentially, is that if two quasars on opposite sides of the sky are sufficiently distant from each other, they would have been out of causal contact since the Big Bang some 14 billion years ago, with no possible means of any third party communicating with both of them since the beginning of the universe—an ideal scenario for determining each particle detector's settings.
<snip>
Physicist Michael Hall says that while the idea of using light from distant sources like quasars is not a new one, the group's paper illustrates the first detailed analysis of how such an experiment could be carried out in practice, using current technology.
"It is therefore a big step to closing the loophole once and for all," says Hall, a research fellow in the Centre for Quantum Dynamics at Griffith University in Australia. "I am sure there will be strong interest in conducting such an experiment, which combines cosmic distances with microscopic quantum effects—and most likely involving an unusual collaboration between quantum physicists and astronomers."
"At first, we didn't know if our setup would require constellations of futuristic space satellites, or 1,000-meter telescopes on the dark side of the moon," Friedman says. "So we were naturally delighted when we discovered, much to our surprise, that our experiment was both feasible in the real world with present technology, and interesting enough to our experimentalist collaborators who actually want to make it happen in the next few years."
<snip>
Researchers propose using distant quasars to test Bell's theorem
Feb 20, 2014 by Jennifer Chu
In a paper published this week in the journal Physical Review Letters, MIT researchers propose an experiment that may close the last major loophole of Bell's inequality—a 50-year-old theorem that, if violated by experiments, would mean that our universe is based not on the textbook laws of classical physics, but on the less-tangible probabilities of quantum mechanics.
<snip>
Though two major loopholes have since been closed, a third remains; physicists refer to it as "setting independence," or more provocatively, "free will." This loophole proposes that a particle detector's settings may "conspire" with events in the shared causal past of the detectors themselves to determine which properties of the particle to measure—a scenario that, however far-fetched, implies that a physicist running the experiment does not have complete free will in choosing each detector's setting. Such a scenario would result in biased measurements, suggesting that two particles are correlated more than they actually are, and giving more weight to quantum mechanics than classical physics.
<snip>
The idea, essentially, is that if two quasars on opposite sides of the sky are sufficiently distant from each other, they would have been out of causal contact since the Big Bang some 14 billion years ago, with no possible means of any third party communicating with both of them since the beginning of the universe—an ideal scenario for determining each particle detector's settings.
<snip>
Physicist Michael Hall says that while the idea of using light from distant sources like quasars is not a new one, the group's paper illustrates the first detailed analysis of how such an experiment could be carried out in practice, using current technology.
"It is therefore a big step to closing the loophole once and for all," says Hall, a research fellow in the Centre for Quantum Dynamics at Griffith University in Australia. "I am sure there will be strong interest in conducting such an experiment, which combines cosmic distances with microscopic quantum effects—and most likely involving an unusual collaboration between quantum physicists and astronomers."
"At first, we didn't know if our setup would require constellations of futuristic space satellites, or 1,000-meter telescopes on the dark side of the moon," Friedman says. "So we were naturally delighted when we discovered, much to our surprise, that our experiment was both feasible in the real world with present technology, and interesting enough to our experimentalist collaborators who actually want to make it happen in the next few years."
<snip>
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