Summary

This book, "Coherent and Incoherent States of the Radiation Field," by Roy J. Glauber, introduces a new mathematical formalism for describing the quantum states of light, specifically distinguishing between coherent and incoherent radiation. Glauber's central thesis is that the statistical properties of light can be fully characterized by a set of quantum-mechanical states, which he terms "coherent states." These states, analogous to classical harmonic oscillator states, possess a well-defined phase and amplitude, making them ideal for describing laser light. The book explains how to represent these states using the coherent state representation and introduces the concept of the P-representation for describing the photon statistics of any light field, thereby providing a rigorous quantum mechanical foundation for understanding optical coherence.

The work lays out the mathematical tools necessary to analyze photon counting experiments and understand the differences between thermal light (incoherent) and laser light (coherent). Readers gain a profound understanding of the quantum nature of light and its statistical behavior, enabling them to analyze and predict the outcomes of various optical phenomena. The book's key ideas revolve around the definition and properties of coherent states, the development of the Glauber correlation functions for quantifying coherence, and the…

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Key concepts

Coherent State — A quantum state of the electromagnetic field that closely resembles a classical electromagnetic wave, with a well-defined amplitude and phase.
P-Representation (Glauber's P-representation) — A diagonal representation of the density operator for the radiation field in terms of the coherent states, useful for calculating expectation values of normally ordered operators.
Photon Statistics — The statistical distribution of the number of photons detected in a given time interval, which can be used to classify different types of light.
Glauber Correlation Functions — Quantities that describe the coherence properties of a light field by correlating the electric field at different space-time points.