This chapter is centered upon the concepts of the quantum nature of light. It begins with a discussion of the photoelectric effect, which provides historical background and a vehicle to discuss the properties of photons. In addition, the photoelectric effect provides the starting point for the explanation of the production of X-rays. After a study of the X-ray spectrum, Compton scattering is introduced as another example of the photon nature of light. As an appendix, the second synthesis opportunity of the volume is presented about lasers. These quantum-electronic devices provide an opportunity to synthesize almost all the topics covered in the volume from the quantum nature of light and matter, to optics, electronics, and thermodynamics. This section is optional, but provides a way to bring the entire text together in the explanation of well-known devices.
This chapter is centered upon the concepts of the quantum nature of light. It begins with a discussion of the photoelectric effect, which provides historical background and a vehicle to discuss the properties of photons. In addition, the photoelectric effect provides the starting point for the explanation of the production of X-rays. After a study of the X-ray spectrum, Compton scattering is introduced as another example of the photon nature of light. As an appendix, the second synthesis opportunity of the volume is presented about lasers. These quantum-electronic devices provide an opportunity to synthesize almost all the topics covered in the volume from the quantum nature of light and matter, to optics, electronics, and thermodynamics. This section is optional, but provides a way to bring the entire text together in the explanation of well-known devices.
This chapter begins with a survey of early experimental results — the Planck spectrum, the photoelectric effect, and Compton scattering — that are usually presented as evidence for the existence of photons. The photon concept is indeed sufficient to explain these results, but it is not necessary. There are semi-classical models that explain the same data without introducing photons. The crucial experiment, in which light consisting of a single photon reflects from a beam splitter, depends on the essential indivisibility of photons, and it excludes all semi-classical descriptions of light. This discussion is followed by a preview of modern methods of production and detection of individual photons, e.g., spontaneous down conversion and Silicon avalanche-photodiode counters, together with an introduction to the quantum theory of light based on the correspondence principle.
This chapter discusses electromagnetic waves and photons. It begins by reviewing some basic ideas on the properties of waves, introducing the wave properties of radiation. There are several reasons for starting with a discussion of electromagnetic radiation. Historically, it was in this area that the quantum theory first developed. The applications of the light-quantum hypothesis, as it was first called, also provide key pieces of evidence for the quantization of energy in atoms and molecules. The chapter then looks at the evidence for the wave nature of light and of X-rays, before putting these two forms of radiation into the context of electromagnetic radiation in general. It also considers Albert Einstein's analysis of the photoelectric effect. Finally, the chapter assesses the statistical nature of photons.
This chapter introduces fundamental concepts of modern physics that emerged from groundbreaking experiments and theories in the early 20th century. It begins by exploring the photoelectric effect, which demonstrates the particle nature of light (photons) and provides a basis for mathematical analysis of this phenomenon. The chapter then discusses Bragg diffraction and the concept of the wave function, illustrating the wave nature of particles such as electrons, protons, and neutrons, and introducing the idea of wave-particle duality. The probability distribution for an electron, whether trapped in a well or traveling freely, is also examined. Rutherford scattering is presented as a pivotal experiment that revealed the existence of the positively charged atomic nucleus. The chapter further explores atomic spectra, explaining how the discrete wavelengths of emitted light indicate that atomic electrons have restricted, quantized energy levels. The Bohr model of the atom is described and mathematically analyzed to predict the spectrum of hydrogen. Finally, the chapter covers the Balmer-Rydberg formula for mathematically analyzing the spectrum of hydrogen. The content is organized into sections covering the photoelectric effect, Bragg diffraction and the wave function, Rutherford scattering, atomic spectra, and a summary of the key concepts. This chapter provides an introduction to the revolutionary ideas of modern physics, including the dual nature of light and matter and the quantized nature of the atom. The chapter includes numerous worked examples and concludes with problems for the student to apply their knowledge.
This chapter starts with the historical development of quantum mechanics and explanations of key concepts behind fundamental discoveries such as Planck's hypothesis, the photoelectric effect, Bohr's atomic model, Compton scattering, the de Broglie hypothesis, the Pauli exclusion principle, the Schrödinger equation, Heisenberg quantum mechanics and the uncertainty principle, the Born interpretation of wave function, the Davisson and Germer experiment, and Dirac relativistic quantum mechanics, which made important contributions to the foundation of modern quantum mechanics. Concepts like the particle properties of radiation, the wave properties of matter, quantized energy and momentum, and the idea that one can no longer know exactly where a single particle like an electron is at any instant of time are brought out clearly through this chapter. A list of important quantum mechanical parameters along with solved examples and unsolved exercises on the key concepts are included towards the end.
You have probably encountered a system known as an "electric eye," which senses light from an artificial source or the sun. This information is used to open doors, count pedestrian or auto traffic, turn on lights at sunset, read holes in punched card, and for a host of other applications. Most of these devices are based on the photoelectric effect, which is the light-induced emission of electrons from atoms. The photoelectric effect completely baffled physicists at the time of its discovery. Einstein's explanation of this process, which won the Nobel Prize in 1921, was a major part of the twentieth-century revolution in physics known as the quantum theory. In this module we shall study the photoelectric and Compton effects, the processes that clearly demonstrate that the energy and momentum in electromagnetic waves are transferred as discrete entities called photons.
Covering a number of important subjects in quantum optics, this textbook is an excellent introduction for advanced undergraduate and beginning graduate students, familiarizing readers with the basic concepts and formalism as well as the most recent advances. The first part of the textbook covers the semi-classical approach where matter is quantized, but light is not. It describes significant phenomena in quantum optics, including the principles of lasers. The second part is devoted to the full quantum description of light and its interaction with matter, covering topics such as spontaneous emission, and classical and non-classical states of light. An overview of photon entanglement and applications to quantum information is also given. In the third part, non-linear optics and laser cooling of atoms are presented, where using both approaches allows for a comprehensive description. Each chapter describes basic concepts in detail, and more specific concepts and phenomena are presented in 'complements'.