Abstract

Information causality is a physical principle which states that it is the sender, not the receiver, who decides what the message is about. After being expressed more formally it can be shown to hold in both classical and quantum information theory. However, if quantum mechanics were even a little more non-local this principle would be violated. The main aim of finding operational principles like information causality that limit the nonlocal correlations allowed by probabilistic theories is that they help to explain the phenomenon of non-locality without referring to the mathematical structure of any particular theory. This is the first step to deriving quantum mechanics from principles which are not just about Hilbert space but are meaningful. Furthermore, operational principles are quite useful for more practical task of bounding the performance of various information processing protocols. In this talk I introduce information causality and show how it can be derived from the properties of mutual information. I also give reasons why one does not have to derive it and can simply assume it. Then I describe the consequences of this principle for acceptable probability distributions.