Oxford University Press eBooks

The Duality of Particles and Waves: Photons

Christopher C. Gerry, Kimberley M. Bruno

Published Feb 21, 2013• 0 citations

Abstract

This chapter discusses the dual nature of small particles, focusing on photons. Photons enable wave-like phenomenon, such as light, to exhibit the kind of behavior expected of particles. Unlike the electron, the photon has no mass, which in turn means that the position of a photon is not well defined. However, a photon can still have a well-defined direction of propagation, and it is this aspect of it that allows photons, excitations of the electromagnetic field, to behave like particles in an appropriate experimental arrangement. The chapter discusses single-photon experiments, delayed-choice experiments, and interaction free measurement.

DOI: 10.1093/acprof:oso/9780199666560.003.0003

Related papers

Waves and Particles

Daniel D. Pollock

Einstein assumed duality between radiation and particles. Experiments involving electrons and diffraction effects are described to illustrate such behaviors. Classical physics and Einstein’s findings unmistakably demonstrated that light possessed both wave and particle properties. The responses of electrons in electric and magnetic fields are evidence for their existence as charged particles. The relationship between particle- and wave-like behavior was given by de Broglie in 1924. The dual nature of electrons was demonstrated experimentally by Davisson and Germer, when studying the diffraction of a stream of electrons. The reflection or diffraction of a beam of electromagnetic radiation can be expected to change its intensity, but changes in its wavelength would not ordinarily be anticipated. Photons and electrons may be described in terms of waves, but this approach has inherent limitations. The greater the attempt that is made to study the nature or behavior of a photon or a particle, the greater will be the uncertainty or error of the measurements.

CRC Press eBooksOct 1, 20200 citations

Quantum interference and quantum erasure

Muhammad Sabieh Anwar, Faizan-e-Ilahi, Syed Bilal Hyder +1 more

Photons are discrete particles of light, yet they undergo interference, a phenomenon typically demonstrated by waves. This phenomenon, known as “wave-particle duality,” is inexplicable in classical physics. In this chapter, we discuss two experiments. The first experiment demonstrates how photons can undergo interference and how measurement can force photons to give up their wave nature and behave like particles that cannot interfere. The second experiment adds to the surprise, showing that it is not only the measurement of the photon under consideration that can force it to change its nature but also that of its entangled twin.

Institute of Physics eBooksAug 1, 20240 citations

Wave–particle duality

Peter Gibbins

The simplest but deepest questions of the philosophy of quantum mechanics are these: Are quantum systems waves, or are they particles? Are they both or are they neither? When light bounces an electron out of the surface of an alkali metal it behaves like a particle. Light carries momentum but also a punch. Just as there is no such thing as half a punch, so there is no such thing as half a quantum of light. On the other hand, the shadow formed on a screen by an object has soft edges, edges which get softer as the object is moved away from the screen. Light exhibits the phenomena of diffraction and interference and so is wavelike. This dual behaviour of light, and indeed of matter itself, is called wave-particle duality. The wave nature of a quantum system is reflected in wave mechanics which assigns a wave-function to the system. But the dual nature of light was noticed before Schrodinger developed the wave-mechanical formalism in 1926. In fact, it goes back at least as far as Einsteins explanation of the photoelectric effect in 1905. Wave-particle duality is not something that arises within the quantum mechanical formalism. It is something which is expressed within it, and is something which is best discussed in terms of the paradoxes that quantum experiments force upon physics. In fact, the simplest and most immediately disturbing of the quantummechanical paradoxes arise out of wave-particle duality. We take the two-slit experiment and the delayed-choice experiment as examples.

Cambridge University Press eBooksSep 25, 19870 citations

The Duality of Particles and Waves: The Split Personality of Electrons

Christopher C. Gerry, Kimberley M. Bruno

This chapter discusses the dual nature of small particles, focusing on electrons. It begins by describing how the classical laws of physics, which were mostly established by the start of the twentieth century, did not work very well when applied on the atomic scale. In order to explain the atomic-scale phenomena, a new kind of physics was invented in the 1920s. This new physics was called quantum physics, or quantum mechanics. It applied to the world on the scale of the atom—the microscopic world, or microworld. The discussions then turn to an experiment involving ‘quantum’ coins; the difference between superposition state and mixed state; light, waves, and interference; and interference with electrons.

Oxford University Press eBooksFeb 21, 20130 citations

Dual Natures of Light and Electromagnetic Fields

Henok Tadesse

The wave-particle dual nature of light was discovered from experimental observations and from theoretical works of Max Planck and Albert Einstein during the beginning of the twentieth century. This paper reveals that wave-particle duality is just one aspect of the all dual nature of light (electromagnetic waves) and electromagnetic fields and that light and electromagnetic fields manifest dual natures in other ways also. For example, light is not only a local phenomenon as conventionally viewed, but also a non-local phenomenon. Light behaves both according to ether theory and emission theory. The speed of light is both constant (c) and variable ( c ± V). The phase velocity of light is independent of source and observer velocity and is always constant c, while the group velocity of light varies with observer velocity but is independent of source velocity. Light acts as if it travels both in a straight line and in curved path, at the same time! Electrostatic lines of force behave as if they are both straight and curved lines. Electrostatic fields behave as if they ‘propagate’ both at the speed of light and with infinite speed, at the same time! This paper is a summary of the findings reported in previous papers published by this author. An extensive theoretical research carried out by this author in an attempt to explain the Michelson-Morley experiment, the Sagnac effect and other light speed experiments led to uncovering of the broader and more fundamental nature of duality in electromagnetism.

Aug 1, 20170 citations

Duality of Light and Matter

Z. Ficek

Arguments about particles or waves gave way to a recognized need for both particles and waves in the description of radiation. The confusion over particle versus wave properties was resolved by Louis de Broglie. He postulated that since light has a dual wave–particle nature, matter also has this nature. The idea was to perform a diffraction experiment with electrons. An interference pattern was demonstrated not only with electrons, but also with many kinds of material particles like protons and neutrons. However, any attempt to observe an interference pattern with neutral atoms was found difficult by the fact that atoms carried no charge as electrons do and could not penetrate through condensate matter like neutrons. The de Broglie wavelength of an electron in the smallest orbit turns out to be exactly equal to the circumference of the orbit predicted by Bohr. The interpretation of the interference phenomenon becomes more subtle when the light beams are replaced by individual photons or particles.

Mar 3, 20170 citations