Oxford University Press eBooks
Coherent Interactions of Fields with Atoms
Stephen Colby Rand
Abstract
Chapter 5 begins the systematic application of the density matrix to describe optical interactions. Stationary two-and three-level atoms interacting with a traveling wave are compared to show that the presence of additional levels changes the saturation behavior of atoms. Then motion of the atoms is introduced and the phenomena of spatial and frequency-domain hole-burning are analyzed. Special effects due to standing waves, such as the light shift, are covered in this section. Next, tri-level coherence is considered, to extend the concept of coherences to two-photon transitions or Zeeman interactions in folded 3- or Λ-systems. Higher order interactions are also analyzed. This includes four-wave mixing and pump–probe techniques which form the basis of common nonlinear laser spectroscopies. Quantum interference is covered as a prelude to the topic of electromagnetically induced transparency. Higher order coherent interactions are also treated using a diagrammatic calculation technique based on Feynman diagrams.