Single photons created easily to be used in optical quantum information processing

Using lasers to excite just one atom from a cloud of ultra-cold rubidium gas, physicists have developed a new way to efficiently create single photons for potential use in optical quantum information processing and in the study of dynamics and disorder in certain physical systems. Reported today in Science Express, the research was supported by the National Science Foundation and Air Force Office of Scientific Research. The technique takes advantage of the unique properties of atoms that have one or more electrons excited to a condition of near-ionization, the Rydberg state. Atoms in this highly excited state have exaggerated electromagnetic properties and interact strongly with one another, allowing one Rydberg atom to block the formation of additional excited atoms within an area of 10 to 20 microns. That single Rydberg atom can then be converted to a photon, ensuring on average that only one photon is produced from a rubidium cloud containing hundreds of densely-packed atoms.