Minuscule thermal transistor could work at light speed

MIT Technology Review : A new thermal transistor that uses thermal photons rather than phonons may have the potential to one day operate at the speed of light. Developed by Philippe Ben-Abdallah at the Université Paris–Sud in France and Svend-Age Biehs at Carl von Ossietzky University in Germany, the transistor consists of three parts, much like a conventional transistor: a source, a drain, and a gate. The source and drain are made of silica and are kept at different temperatures. They are separated by a gate made of a thin layer of vanadium oxide. To ensure that the heat transfer between the source and drain is radiative, the three layers are separated from each other by a 50-nm gap. Because the vanadium oxide layer switches from being a photon conductor to an insulator as it cools, raising and lowering its temperature acts as the transistor’s on–off switch. Such a device could find use in thermal logic gates for microscopic machines, say the researchers.