Experiments close entanglement loopholes
Slagboom en Peeters Luchtfotografie BV
Some pesky loopholes no longer plague a crucial test for assessing the weirdness of quantum mechanics. Experiments reported in 2015 definitively demonstrate that the quantum world violates locality, the principle that events sufficiently separated in spacetime must be independent. “It’s a landmark result,” says Matthew Leifer, a quantum physicist at the Perimeter Institute for Theoretical Physics in Waterloo, Canada.
The experiments execute a test proposed by physicist John Bell in 1964 to evaluate locality by performing the quantum equivalent of repeatedly flipping two coins simultaneously. If locality applies to the microscopic world, then seeing one coin land heads offers no insight into the landing face of the other coin. There would be a limit to how often one coin’s face