Novel Light Source Emitting Photon Pairs (image) University of Würzburg Share Print E-Mail Caption This is an artistic representation of a two-photon source: The monolayer (below) emits exactly two photons of different frequencies under suitable conditions. They are depicted in red and green in the picture. Credit (Picture: Karol Winkler) Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.