Simplest Model Treatment of the Classical Interaction of Light with Matter

Yuriy Akimov

Understanding of light-matter interaction is a keystone in mastering classical and quantum optics. This paper gives an overview of the fundamental principles used in these two fields for description of light-matter interaction. By exploring the simplest type of matter composed of charge-free particles bearing magnetic moments only, differences in the fundamental principles of classical and quantum optics are discussed and clarified.

Miroslaw Jonasz, Georges R. Fournier

Thomas Erneux, P. Glorieux

Modeling lasers may be realized with different levels of sophistication. Rigorously it requires a full quantum treatment but many laser dynamical properties may be captured by semiclassical or even purely classical approaches. In this book we deliberately chose the simplest point of view, i.e. purely classical equations, and try to extract analytically as much information as possible. The basic framework of our approach is provided by the rate equations . In their simplest version, they apply to an idealized active system consisting of only two energy levels coupled to a reservoir. They were introduced as soon as the laser was discovered to explain (regular or irregular, damped or undamped) intensity spikes commonly seen with solid state lasers (for a historical review, see the introduction in). These rate equations are discussed and sometimes derived from a semiclassical theory in textbooks on lasers. They capture the essential features of the response of a single-mode laser and they may be modified to account for specific effects such as the modulation of a parameter or optical feedback. The most basic processes involved in laser operation are schematically represented in Figure 1.1. N 1 and N 2 denote the number of atoms in the ground and excited levels, respectively. The process of light–matter interaction is restricted to stimulated emission and absorption.

Pavel A Apanasevich

T U Jeevitha

Abstract: An extensive review of the quantum theory of light-matter interaction is given in this chapter, beginning with its fundamental ideas and historical development. It covers the quantization of the electromagnetic field, atomic models, and important interaction Hamiltonians, including both semi-classical and completely quantum treatments. The role of vacuum fluctuations and fundamental processes like spontaneous and induced emission are examined. Quantum coherence, entanglement, decoherence, and its formal representation using master equations are also covered in this chapter. Modern applications such lasers, quantum sensors, and quantum communication systems are highlighted. The significance of light-matter interaction in furthering quantum science and technology is emphasized in the chapter's conclusion, which also discusses current research trends and future directions. Keywords: Laser, cryptography, Electromagnetic, Quantum, Atomic.