Physicists extend entanglement in Einstein experiment (2)

Using a photon fission process, physicists have split a single photon into a pair of daughter photons and then split one of the daughter photons into a pair of granddaughters to create a total of three photons. All three photons, the scientists showed, share quantum correlations between their energies (corresponding to their momentums) and between their emission times (corresponding to their positions). The study marks the first experimental demonstration of energy-time entanglement of three or more individual particles, building on the original two-particle version proposed by Einstein, Podolsky, and Rosen (EPR) 77 years ago.