Abstract Neutron optics refers to phenomena which arise from the interference between the incident and the scattered neutron waves. This is in contrast to the topics in earlier chapters of this book, where we have been concerned with interference between the scattered waves alone. The wave Halban and Preiswerk (1936) and by Mitchell and Powers (1936) using ‘white’ neutrons from a radium–beryllium source, and more convincingly by Zeilinger et al. (1988) using monochromatic neutrons from a reactor source. The subject of neutron optics itself began with the work of Fermi and Zinn (1946), who demonstrated the mirror reflection of a collimated beam of thermal neutrons. Since then nearly all the classical optical phenomena of reflection, refraction and interference have been shown to occur with neutrons.
Abstract Neutron optics refers to phenomena which arise from the interference between the incident and the scattered neutron waves. This is in contrast to the topics in earlier chapters of this book, where we have been concerned with interference between the scattered waves alone. The wave Halban and Preiswerk (1936) and by Mitchell and Powers (1936) using ‘white’ neutrons from a radium–beryllium source, and more convincingly by Zeilinger et al. (1988) using monochromatic neutrons from a reactor source. The subject of neutron optics itself began with the work of Fermi and Zinn (1946), who demonstrated the mirror reflection of a collimated beam of thermal neutrons. Since then nearly all the classical optical phenomena of reflection, refraction and interference have been shown to occur with neutrons.
A range of phenomena similar or analogous to those of classical optics is exhibited by slow neutrons. The aim of this review is to discuss this similarity and to display the results obtained in a wide range of experimental work on reflection, refraction, diffraction and interference of neutrons. The motivation of such experiments is discussed in the introductory section. The review is divided into three main sections: geometrical optics, wave optics and crystal optics; with subsections that parallel the typical textbook development of classical optics. Special emphasis is placed on the recent developments in neutron interferometry and on the fundamental tests of quantum-mechanical principles made possible by these novel techniques.
This book presents a systematic account of optical coherence theory within the framework of classical optics, as applied to such topics as radiation from sources of different states of coherence, foundations of radiometry, effects of source coherence on the spectra of radiated fields, coherence theory of laser modes, and scattering of partially coherent light by random media. The book starts with a full mathematical introduction to the subject area and each chapter concludes with a set of exercises. The authors are renowned scientists and have made substantial contributions to many of the topics treated in the book. Much of the book is based on courses given by them at universities, scientific meetings and laboratories throughout the world. This book will undoubtedly become an indispensable aid to scientists and engineers concerned with modern optics, as well as to teachers and graduate students of physics and engineering.
Electromagnetic optical phenomena are generally understood via Maxwell’s equations for the electric and magnetic vector fields. Neutron optical phenomena are based upon de Broglie matter waves and the Schrödinger wave equation which involves a scalar wave function. Nevertheless, a description of interference effects requires the solution of a Helmholtz scalar wave equation in both cases. Gravitational, inertial, and motional effects lead to rather large phase shifts in neutron interferometry. This chapter describes how the quantum phase shift is calculated, usually by evaluating the action as an integral over the Lagrangian. A connection to relativity theory is given when the Compton frequency depending on the mass of the neutron is taken as a physical quantity. It concludes with a list of the approximately 40 neutron interferometry experiments carried out in various laboratories worldwide, which form the subject of this book.
Most scientists immediately associate optics with photons. Indeed optics, defined as the study of the properties of light, is one of the oldest fields of physics – dating back to the earliest civilisations – and is still a thriving area of research. But there is more to optics than light and lasers. “Matter wave” optics, where electrons and neutrons take the place of photons, began with the demonstration of the wave nature of the electron by G P Thomson, Davisson and Germer n the 1920s. Since then electron and neutron interferometers have been used in many beautiful experiments that have improved our understanding of quantum mechanics. Beams of electrons and neutrons have also become indispensable tools in the study of solids and surfaces. Therefore it was perhaps inevitable that one day physicists would be able to do optics with atoms – to coherently split, focus and refract beams of neutral atoms.
Abstract The quantum interference of DeBroglie matter waves is probably one of the most startling and fundamental aspect of quantum mechanics. It continues to tax our imaginations and leads us to new experimental windows on nature. Quantum interference phenomena are vividly displayed in the wide assembly of neutron interferometry experiments, which have been carried out since the first demonstration of a perfect silicon crystal interferometer in 1974. Since the neutron experiences all four fundamental forces of nature (strong, weak, electromagnetic, and gravitational), interferometry with neutrons provides a fertile testing ground for theory and precision measurements. Many Gedanken experiments of quantum mechanics have become real due to neutron interferometry. This book provides the reader with a detailed account of neutron interferometry experiments. The basic ideas and experiments related to coherence properties of matter waves and various post-selection criteria, gravitationally induced phase shifts, Berry's geometrical phase, spinor symmetry and spin superposition, Aharonov-Bohm topological interference effects, and the neutron version of the Sagnac effect are presented in a self-contained and pedagogical way. Interferometry with perfect crystals, artificial lattices, and spin-echo systems are topics of this book. It includes the theoretical motivations as well as connections to other areas of experimental physics, such as quantum optics, nuclear physics, gravitation, and atom interferometry. The book is written in a style that will be suitable at the beginning graduate level, and will excite many students and researchers in neutron physics, quantum optics, and atomic physics. Lecturers teaching courses in modern physics and quantum mechanics will find a number of interesting and historic experiments they may want to include in their lectures.
Abstract Coherence phenomena play an important role in any kind of interferometry (Gabor 1956; Glauber 1963; Mandel and Wolf 1965, 1995; Born and Wolf 1975; Walls and Milburn 1994; Mandel and Wolf 1995). In this chapter we summarize some known results, add some new ones obtained with neutrons, and analyse them in terms of general quantum optics, which can be applied to photon and matter waves as well. Indeed, neutrons have many well-known particle properties, but in interference experiments they behave like wave fields, which provides the connection to the quantum optical terminology. Coherence appears as a system property (neutron + apparatus) which persists as long as it does not become destroyed by statistical or dissipative effects.