Researchers measure connections between photon pairs in beam of light
Intricate quantum connections between microscopic particles almost certainly underlie some phenomena perceivable at human scales. Now, for the first time, physicists have measured these connections, known as quantum entanglement, between pairs of photons within a macroscopic beam of light. It’s a step toward understanding how the rules of quantum mechanics scale up to phenomena such as superconductivity that involve large numbers of particles.
In the experiment, described in a study to appear in Physical Review Letters, researchers filtered a specially prepared light beam to observe individual photons and chart the quantum links between them. “Nobody has looked at light in this manner before,” says Alexander Lvovsky, a quantum physicist at the University of Calgary. The physicists confirmed theoretical predictions that all the photons would exhibit some