Nonlocality gets more real

"Bell's Inequalities," the set of mathematical relations that would rule out the notion that distant quantum particles exert influences on each other at seemingly instantaneous rates, have now been violated over record large distances, with record high certainty, and with the elimination of an important loophole in three recent experiments, further solidifying the notion of "spooky action at a distance" in quantum particles. At the Optical Society of America meeting in Baltimore earlier this month, Paul Kwiat of Los Alamos and his colleagues announced that they produced an ultrabright source of photon pairs for Bell's inequality experiments; they went on to verify the violation of Bell's inequalities to a record degree of certainty. Splitting a single photon of well-defined energy into a pair of photons with initially undefined energies, and sending each photon through a fiber-optic network to detectors 10 km apart, researchers in Switzerland showed that determining the energy for one photon by measuring it had instantaneously determined the energy of its neighbor 10 km away-a record set by the researchers last year but now demonstrated in an improved version of the original experiment. A University of Innsbruck group performed Bell measurements with detectors that randomly switched between settings rapidly enough to eliminate the "locality loophole," which posited that one detector might somehow send a signal to the other detector at light or sub-light speeds to affect its reading.

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