Final Report Summary - GEQIT (Generalized (quantum) information theory) The significance of the notion of information in physics has been recognised since a long time. However, due to a lack of appropriate information-theoretic techniques, it has not usually been possible to turn information-inspired ideas related to physics into concrete quantitative statements. The main goal of the project GEQIT was to provide these missing techniques, and to show how they can be used to gain novel insights on questions in physics. This goal has now been achieved. The core technical ingredient for this is a novel notion of entropy, which generalises both information-theoretic and thermodynamic entropy. To demonstrate its use, we have shown, for instance, that it correctly quantifies the amount of heat that is generated in logically irreversible processes, or that it characterises the information-theoretic conditions under which thermodynamic systems thermalise. This establishes a quantitative link between quantities defined in information theory and quantities relevant to thermodynamics.
