Field Quantization

Abstract

Up to now, we have treated many problems in light-matter interactions and have obtained results in excellent agreement with experiments without having to quantize the electromagnetic field. Such a semiclassical description is sufficient to describe most problems in quantum optics. However, there are a few notable exceptions where a classical description of the field leads to the wrong answer. These include spontaneous emission, the Lamb shift, resonance fluorescence, the anomalous gyromagnetic moment of the electron, and “nonclassical” states of light such as squeezed states. The remainder of this book deals with selected problems in light-matter interaction that require field quantization. The present chapter treats the quantization of the electromagnetic field in free space. Those familiar with this subject might want to glance at our notation and then proceed directly to Chap. 14.