Three's a charm: NIST detectors reveal entangled photon triplets

Researchers at the University of Waterloo in Canada have directly entangled three photons in the most technologically useful state for the first time, thanks in part to superfast, super-efficient single-photon detectors developed by the National Institute of Standards and Technology.

Entanglement is a special feature of the quantum world in which certain properties of individual particles become linked such that knowledge of the quantum state of any one particle dictates that of the others. Entanglement plays a critical role in quantum information systems. Prior to this work it was impossible to entangle more than two photons without also destroying their fragile quantum states.

Entangled photon triplets could be useful in quantum computing and quantum communications—technologies with potentially vast power based on storing and manipulating information in quantum states—as well as achieving elusive goals in physics dating back to Einstein. The team went on to use the entangled triplets to perform a key test of quantum mechanics.