  In his famous letter in 1870, Maxwell describes how Joule's law can be
violated "only by the intelligent action of a mere guiding agent", later coined
as Maxwell's demon by Lord Kelvin. In this letter we study thermodynamics of
information using an experimentally feasible Maxwell's demon setup based a
single electron transistor capacitively coupled to a single electron box, where
both the system and the Demon can be clearly identified. Such an engineered
on-chip Demon measures and performes feedback on the system, which can be
observed as cooling whose efficiency can be adjusted. We present a detailed
analysis of the system and the Demon, including the second law of
thermodynamics for bare and coarse grained entropy production and the flow of
information as well as efficiency of information production and utilization.
Our results demonstrate how information thermodynamics can be used to improve
functionality of modern nanoscale devices.
