Research Highlights

Nature 464, 145 (11 March 2010) | doi:10.1038/464145a; Published online 10 March 2010

Physics: Photon storage for telecoms

Phys. Rev. Lett. 104, 080502 (2010)

Photons have a quantum mechanical spin, which can be 'up', 'down' or both. Storing a photon using conventional methods alters this state, destroying its quantum information.

Björn Lauritzen and his colleagues at the University of Geneva in Switzerland have found a way to store infrared photons without changing them. The team shone a weak infrared laser pulse at a crystal containing erbium atoms, which had previously been excited with a different light pulse. As an infrared photon was absorbed by the crystal, its quantum state spread across many erbium atoms.

Using an electric-field gradient, the group triggered the crystal's re-emission of a photon encoding the same information as the incident photon a few hundred nanoseconds later. The efficiency was well below 1%, but the technique could prove useful in quantum-communication devices, the authors say.