The main focus of this textbook is the basic unit of information and the way in which our
understanding of this has evolved over time. In particular the author covers concepts related
to information classical computing logic reversible computing quantum mechanics quantum
computing thermodynamics and some artificial intelligence and biology all approached from the
viewpoint of computer sciences. The book begins by asking the following nontrivial question:
what is a bit? The author then discusses logic logic gates reversible computing and
reversible architectures and the concept of disorder. He then tries to establish the
relationship between three essential questions that justify quantum approaches in computer
sciences: the energy required to perform a real-life computation the size of current
processors and the reversibility of quantum operations. Based on these concepts the author
establishes the conditions that justify the use of quantum techniques for certain kinds of
computational tasks and he uses formal descriptions and formal argumentations to introduce key
quantum mechanical concepts and approaches. The rest of the book is formally different
focusing on practical issues including a discussion of remarkable quantum algorithms in a
treatment based on quantum circuit theory.The book is valuable for graduate students in
computer science and students of other disciplines who are engaged with physical models of
information and computing.
