$double slit diffraction$

Furthermore, versions of the experiment that include detectors at the slits find that each detected photon passes through one slit (as would a classical particle), and not through both slits (as would a wave).

$double slit diffraction$

However, the light is always found to be absorbed at the screen at discrete points, as individual particles (not waves) the interference pattern appears via the varying density of these particle hits on the screen. The wave nature of light causes the light waves passing through the two slits to interfere, producing bright and dark bands on the screen – a result that would not be expected if light consisted of classical particles. In the basic version of this experiment, a coherent light source, such as a laser beam, illuminates a plate pierced by two parallel slits, and the light passing through the slits is observed on a screen behind the plate. Another version is the Mach–Zehnder interferometer, which splits the beam with a beam splitter. Changes in the path-lengths of both waves result in a phase shift, creating an interference pattern.

$double slit diffraction$

The experiment belongs to a general class of 'double path' experiments, in which a wave is split into two separate waves (the wave is typically made of many photons and better referred to as a wave front, not to be confused with the wave properties of the individual photon) that later combine into a single wave. He believed it demonstrated that Christiaan Huygens' wave theory of light was correct, and his experiment is sometimes referred to as Young's experiment or Young's slits. Thomas Young's experiment with light was part of classical physics long before the development of quantum mechanics and the concept of wave–particle duality. In 1927, Davisson and Germer demonstrated that electrons show the same behavior, which was later extended to atoms and molecules. With the beginning of modern physics, about a hundred years later, it was realized that light could in fact show behavior characteristic of both waves and particles. At that time it was thought that light consisted of either waves or particles. This type of experiment was first performed by Thomas Young in 1801, as a demonstration of the wave behavior of visible light. In modern physics, the double-slit experiment is a demonstration that light and matter can display characteristics of both classically defined waves and particles moreover, it displays the fundamentally probabilistic nature of quantum mechanical phenomena.

$double slit diffraction$

Light from a green laser passing through two slits 0.4mm wide and 0.1mm apart

$double slit diffraction$

Double slit diffraction