An introduction to quantum communications networks : or how shall we communicate in the quantum era This book fills a gap between experts and non experts in the field by providing readers with the basic tools to understand the latest developments in quantum communications and its future directions. With the fast pace of developments in quantum technologies it is more necessary than ever to make the new generation of students in science engineering familiar with the key ideas behind such disruptive systems. This book describes key applications for quantum networks; local metropolitan and global networks; and the industrial outlook for the field.