The toughest test of quantum theory ever conducted has verified the "spooky action at a distance," in which manipulating one object instantaneously seems to affect another, remote object, is inherent to the quantum domain.
The test represents a new assessment of physicist John Bell's test for differentiating between Einstein's hidden variables and the spooky interpretation of quantum mechanics. Bell theorized concealed variables can explain correlations only up to some maximum limit, and if that level is surpassed, then Einstein's model must be incorrect.
Previous experiments were susceptible to certain loopholes, which force testers to assume the properties of the photons they capture are representative of the entire set. Delft University of Technology researchers report closing these loopholes via entanglement swapping.
They began with two unentangled electrons in diamond crystals held in different labs on campus, 1.3 kilometers between them. Each electron was individually entangled with a photon, and both photons were transmitted to a third location where the two photons were entangled with each other, causing entanglement in their paired electrons as well. The researchers produced 245 entangled electron pairs and exceeded Bell's limits.
One expert says this type of test has ramifications for quantum cryptography, and could potentially make it hackable.
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