I consider teaching to have been one of my greatest privileges in life. I have al ways attemped to make a matter, sometimes difficult, sometimes in constant evolution, simpler and easier to understand. There comes a time then, when one feels the necessity to write and publish a book. For this reason, I have already published (in french) several lecture books on Classical Mechanics, Quantum Mechanics, Matrix Optics, Electroweak Interaction, General Rel ativity and Gravitation, Cosmology. Teaching quantum theory has been a particular delight as its constant evolution and enlargement, embraces...