Classical and quantum information: two kinds of information?

Abstract

The aim of this article is to offer a conceptual analysis of the notion of information, on the basis of the way in which it is defined by the theories of Claude Shannon and of Benjamin Schumacher. Against the position according to which there are two kinds of information of different natures, a classical information and a quantum information (defined by the theories of Shannon and Schumacher respectively), here we argue that there are not sufficient reasons to maintain the existence of quantum information as a new and substantially different kind of information. So we claim that there is only one kind of information, which can be encoded in different ways, in particular, by means of classical or quantum systems. This position will lead us to conceive an unified and abstract concept of information in a context where (a) Shannon's theory is neutral and independent from the physical theories used to describe the stages involved in the process of transmitting information, and (b) Schumacher's theory does not define a new kind of informational entity, but a alternative way of coding information by means of quantum states.