Physicists extract photons from diamond ring

Physicists in the US are the first to make an integrated device that extracts photons from a tiny piece of diamond before the light is sent through a waveguide to the outside world. The photons all have the same frequency and originate in a nitrogen vacancy (NV), which is a defect that occurs in diamond when two neighbouring carbon atoms are replaced by a nitrogen atom and an empty lattice site. According to the researchers, the chip could be used to create quantum-information technology such as quantum repeaters.