Scientists investigating how light particles (or photons) experience entanglement on the quantum scale have discovered something entirely unexpected, and it challenges long-held assumptions about the initial moments of what Einstein referred to as "spooky action at a distance".

When the team created entangled pairs of photons, these particles didn't originate in the same place and break away as predicted - they emerged from entirely different points in space, which means quantum theory might have to account for a whole lot more randomness than we thought.

"Until now, it has been assumed that such paired photons come from the same location," says one of the researchers, David Andrews from the University of East Anglia in the UK. 

"Now, the identification of a new delocalised mechanism shows that each photon pair can be emitted from spatially separated points, introducing a new positional uncertainty of a fundamental quantum origin."

The team figured this out by performing a very simple entanglement experiment called spontaneous parametric down-conversion (SPDC), which involves firing photon beams through a crystal such as barium borate, to generate entangled pairs of light particles...

Full story: http://www.sciencealert.com/this-strange-behaviour-of-light-particles-challenges-our-understanding-of-quantum-theory