Molecular transistor

Researchers in Switzerland have successfully created an optical transistor from a single molecule.

The development from ETH Zurich, the Swiss Federal Institute of Technology, has brought researchers one step closer to an optical computer.

Such a technology has been the goal of scientists who have been trying for years to find ways to produce integrated circuits that operate on the basis of photons instead of electrons. This is because photons do not only generate much less heat than electrons, but they also enable considerably higher data transfer rates.

Although a large part of telecommunications engineering nowadays is based on optical signal transmission, the necessary encoding of the information is generated using electronically controlled switches. A compact optical transistor is still a long way off.

The ETH research group was able to create an optical transistor with a single molecule by making use of the fact that a molecule’s energy is quantised. When laser light strikes a molecule that is in its ground state, the light is absorbed. As a result, the laser beam is quenched. Conversely, it is possible to release the absorbed energy again in a targeted way with a second light beam. This occurs because the beam changes the molecule’s quantum state, with the result that the light beam is amplified.