An Overview of Quantum Electrodynamics and Matter-Radiation Field Interaction

For light is much more mobile, is composed Of finer particles, yet has more power, 

Lucretius (c.99-c.55 BCE The way things are translated by Rolfe Humphries, Indiana University Press, 1968 

Many dynamical processes of interest are either initiated or probed by light, and their understanding requires some knowledge of this subject. This chapter is included in order to make this text self contained by providing an overview of subjects that are used in various applications later in the text. In particular, it aims to supplement the elementary view of radiation-matter interaction as a time-dependent perturbation in the Hamiltonian, by describing some aspects of the quantum nature of the radiation field. This is done on two levels The main body of this chapter is an essentially qualitative overview that ends with a treatment of spontaneous emission as an example. The Appendix gives some more details on the mathematical structure of the theory. 

In elementary treatments of the interaction of atoms and molecules with light, the radiation field is taken as a classical phenomenon. Its interaction with a molecule is often expressed by 

This picture is developed to a high level of sophistication within the classical theory of the electromagnetic field, where dynamics is described by the Maxwell equations. Some basics of this theory are described in Appendix 3 A. Here we briefly outline some of the important results of this theory that are needed to understand the nature of the interaction between a radiation field and a molecular system. 

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AN OVERVIEW OF QUANTUM ELECTRODYNAMICS AND MATTER-RADIATION FIELD INTERACTION... 

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