Light from ancient quasars helps confirm quantum entanglement
Results are among the strongest evidence yet for spooky action at a distance.
Jennifer Chu | MIT News Office
August 19, 2018
Last year, physicists at MIT, the University of Vienna, and elsewhere provided strong support for quantum entanglement, the seemingly far-out idea that two particles, no matter how distant from each other in space and time, can be inextricably linked, in a way that defies the rules of classical physics.
Take, for instance, two particles sitting on opposite edges of the universe. If they are truly entangled, then according to the theory of quantum mechanics their physical properties should be related in such a way that any measurement made on one particle should instantly convey information about any future measurement outcome of the other particle correlations that Einstein skeptically saw as spooky action at a distance.
In the 1960s, the physicist John Bell calculated a theoretical limit beyond which such correlations must have a quantum, rather than a classical, explanation.
But what if such correlations were the result not of quantum entanglement, but of some other hidden, classical explanation? Such what-ifs are known to physicists as loopholes to tests of Bells inequality, the most stubborn of which is the freedom-of-choice loophole: the possibility that some hidden, classical variable may influence the measurement that an experimenter chooses to perform on an entangled particle, making the outcome look quantumly correlated when in fact it isnt.
More:
http://news.mit.edu/2018/light-ancient-quasars-helps-confirm-quantum-entanglement-0820