Singles become pairs: New insights into the light scattering of atoms

Researchers at the Humboldt University of Berlin have demonstrated a surprising effect present in the fluorescent light of a single atom. Researchers headed by Jürgen Volz and Arno Rauschenbeutel from the Department of Physics at the Humboldt University of Berlin have gained new insights into the scattering of light by a fluorescent atom, which could also be useful for quantum communication. The research team has now published their results in the scientific journal Nature Photonics. In 1900, Max Planck formulated the hypothesis that light cannot exchange arbitrary amounts of energy with matter, such as an atom, but only certain discrete "energy packets" called quanta. Five years later, Albert Einstein then proposed that these quanta were not a mere computational quantity, but that light itself consisted of quanta, which we now call photons. In fact, nowadays there are photodiodes which are sensitive enough to register a single photon. With continuous illumination, these do not produce a steady electrical signal, but rather a series of short current pulses.