Using a block of three separated solid elements, a thermal source and drain
together with a gate made of an insulator-metal transition material exchanging
near-field thermal radiation, we introduce a nanoscale analog of a field-effect
transistor which is able to control the flow of heat exchanged by evanescent
thermal photons between two bodies. By changing the gate temperature around its
critical value, the heat flux exchanged between the hot body (source) and the
cold body (drain) can be reversibly switched, amplified, and modulated by a
tiny action on the gate. Such a device could find important applications in the
domain of nanoscale thermal management and it opens up new perspectives
concerning the development of contactless thermal circuits intended for
information processing using the photon current rather than the electric
current