Two research teams from Germany and France have reported that nitrogen impurities in Ib synthetic diamonds can be used as room-temperature single-photon emitters. Such stable and robust sources of single photons could be a boon to the development of quantum cryptography systems. The researchers at Ludwig Maximilian University in Munich, Germany, and the Max Planck Institute for Quantum Optics in Garching, Germany, who published a report on their work in the July 10 issue of Physical Review Letters, monitored the fluorescent response of a diamond sample that they exposed to 532-nm light from a frequency-doubled Nd:YVO4 laser. The team at the Institute of Optics in Orsay, France, excited the crystals with a 10-mW, 514-nm argon-ion laser. In both cases, the fluorescence displayed photon antibunching.