Entangling photons of different colors

Some of the most advanced communication systems now under development rely on the properties of quantum science to store and transport information. However, researchers designing quantum communication systems that rely on light, rather than electric current, to transmit information face a quandary: The optical components that store and process quantum information typically require visible-light photons (particles of light) to operate. However, only near-infrared photons—with wavelengths about 10 times longer—can transport that information over kilometers of optical fibers.