IEEE Spectrum February 4, 2020
In an experiment researchers in Germany transferred the information contained in a single quantum bit from an atomic state to a single photon, then sent it through some 20 kilometers of fiber optic cable. They generated and observed the entanglement between a rubidium atom and a photon whose wavelength was transformed from 780 nm to the telecom S band at 1522 nm. The researchers found they can preserve on average some 78 percent of the entanglement between the rubidium atom and the fiber optic photon. Their next steps are to build out the full atom-to-photon-to-atom quantum communication system within their lab. And then to physically separate one apparatus from another by roughly 20 km and try to make it all work…read more. TECHNICAL ARTICLE
In the ultra-high vacuum glass cell, a single Rubidium atom is captured. It will later be entangled with a photon. Photo: Christoph Olesinski/LMU