Maxwell demon and the correspondence between information and entropy

Thermodynamic models are discussed for various methods of introducing order in a system (for carrying out a control process). The concept of entropic efficiency is introduced as a measure of the degree of irreversibility of various processes (the process approaches reversibility as this efficiency approaches unity from below). Although the efficiency of the Maxwell demon is much less than unity, it is comparable to the efficiency of the Carnot cycle. The efficiency of a model for a modern version of the Maxwell demon is estimated. This modern version is the information approach for producing a population inversion in a two-level maser. A thermodynamic model for the general case of control processes confirms the conclusion that the information acquisition and control processes are intrinsically irreversible.