It is always a great opportunity and pleasure for a professor to introduce a new textbook. This one is especially unusual, in a sense that, first of all, it concerns two fields, namely, classical and quantum information theories, which are rarely taught altogether with the same reach and depth. Second, as its subtitle indicates, this textbook primarily addresses the telecom scientist. Being myself a quantum-mechanics teacher but not being conversant with the current Telecoms paradigm and its community expectations, the task of introducing such a textbook is quite a challenge. Furthermore, both subjects in information theory can be regarded by physicists and engineers from all horizons, including in telecoms, as essentially academic in scope and rather difficult to reconcile in their applications. How then do we proceed from there?

I shall state, firsthand, that there is no need to convince the reader (telecom or physicist or both) about the benefits of Shannon's classical theory. Generally unbeknown to millions of telecom and computer users, Shannon's principles pervade all applications concerning data storage and computer files, digital music and video, wireline and wireless broadband communications altogether. The point here is that classical information theory is not only a must to know from any academic standpoint; it is also a key to understanding the mathematical principles underlying our information society.

Shannon's theory being reputed for its completeness and societal impact, the telecom engineer (and physicist within!) may, therefore, wonder about the benefits of quantum mechanics (QM), when it comes to information.