French researchers observe photons' life and death

PARIS – Researchers from Kastel Brossel Laboratory in France (CNRS/Ecole Normale Supérieure/Collège de France/Université Paris 6) announced they built a photon trap that made possible the observation of birth, life, and death of individual photons.

Researchers said they managed to observe the same unique photon hundreds times. For the experiment, they used a “photon box”, a cavity formed by two supraconductors mirrors cooled to a temperature close to absolute zero. Between the two mirrors (spaced out 2.7 centimeters apart), a photon coming from residual thermal radiation rebounds more than a billion times before disappearing. Eventually, the distance it covers equals the earth circumference.

The team of researchers said they used atoms that have an energy transition between state 0 and state 1, thus different from photons’ energy. They recorded multiple sequences of several seconds during which photons appear and disappear, revealing quantum jumps of light.

By observing those jumps for hours, researchers explained they could verify statistic properties of thermal radiation, as established one century ago by Max Planck and Albert Einstein.

During this experiment, information is carried by a quantum of light and transferred hundreds times to a material system without disappearing. This photon controls the state of a large number of atoms, achieving a major step for quantum data processing, Kastel Brossel Laboratory concluded in a statement issued by the French National Center for Scientific Research (CNRS).