The human eye employs millions of nanoscale photoreceptors that output chemical signals when they are stimulated by photons. By reversing that process, a team of researchers in Northern Ireland and Japan has engineered a tiny molecular transistor that emits photons when supplied with the right chemicals. The researchers showed just how small logic gates can be made when using individual molecules � in this case, 3 nanometers in radius. And besides demonstrating the ability to operate nanoscale molecular logic gates (a capability that has been shown elsewhere in solutions inside test tubes), the team showed how such gates could be embedded in an organic thin film. Arrays of logic gates could be assembled on such membranes, heralding a comprehensive architecture for future molecular-sized computers, the team said.