This book grew out of our work in the field of the quantum theory of nonlinear optics. Some of this work we have done together and some following our own paths. One major emphasis of this work has been the quantization of electrodynamics in the presence of dielectric media. This is a subject that is often given short shrift in many treatments, and we felt that a book in which it receives a more extensive discussion was warranted.

M.H. would like to thank his thesis advisor, Eyvind Wichmann, for an excellent education in quantum mechanics and quantum field theory, and M. Suhail Zubairy for introducing him to the field of nonlinear optics with quantized fields. Others who played a major role are Leonard Mlodinow, with whom the initial work on quantization in nonlinear media was done, and Janos Bergou and Vladimir Buzek, long-time collaborators with whom it has been a pleasure to work. He also thanks Carol Hutchins for many things.

P.D.D. wishes to acknowledge his parents and family for their invaluable support. The many colleagues who helped form his approach include Crispin Gardiner and the late Dan Walls, who pioneered quantum optics in New Zealand. Subhash Chaturvedi, Howard Carmichael, Steve Carter, Paul Kinsler, Joel Corney, Piotr Deuar and Kaled Dechoum have contributed greatly to this field. He also thanks Margaret Reid, who has played a leading role in some of the developments outlined in the quantum information section, and Qiongyi He, who provided illustrations.