Scientists at the University of East Anglia (UEA) have discovered that when photons are created in pairs, these fundamental light particles can emerge from different locations. This may have a significant impact on both the study of quantum physics and quantum computing, because up until now scientists believed that these kinds of photon pairs originated from single points in space.
The team was passing photon beams through crystals to produce entangled pairs of photons in order to study the process called spontaneous parametric down-conversion (SPDC). David Andrews of UEA's School of Chemistry said in a press release:
“When the emergent pairs equally share the energy of the input, this is known as degenerate down-conversion, or DDC. Until now, it has been assumed that such paired photons come from the same location. Now, the identification of a new delocalized mechanism shows that each photon pair can be emitted from spatially separated points, introducing a new positional uncertainty of a fundamental quantum origin.”
Quantum entanglement is critical to a range of quantum applications, from computing to teleportation. These findings, published in Physical Review Letters, illustrate that photons are not the pinpoint-accurate, sharply-defined bits of light we've conceived of in the past, and that there are limits to spatial resolution.
“Everything has a certain quantum 'fuzziness' to it, and photons are not the hard little bullets of light that are popularly imagined,” Andrews concluded int the press release.