The broad scope and inevitable limitations in the size of the book dictated
choices as to topics included, which were guided by the need to provide the
necessary background, in a self-contained fashion, so that the material can be
followed without recourse to other texts. Thus the chapters on quantum theory
represent a preparation for the understanding of quantum optics, which in
turn serves the purpose of illustrating physical implementations of quantum
information processing. The discussion of quantum information and computation
emphasizes the physical rather than the computer science aspects or
the underlying mathematical structure. Obviously, a number of topics found
in texts of quantum optics or quantum information and computation have
been left out. On the other hand, a few topics representing relatively recent
developments, not yet in books, have been included, as they seem, at least
to us, to complement the tools and physical concepts for the implementation
of quantum computation. The assumption is that equipped with the tools
and phenomenology provided in this book, the student should be prepared to
handle more specialized texts.