Young's double-slit experiment demonstrates clearly the propagation of light in the form of a wave motion. Common attempts at a quantized picture of the experiment tend to describe light in terms of the propagation of small spatially localized particles. This is wrong, and unnecessary if quantization of the electric and magnetic field vectors is considered properly. Interference between normal modes of the field is a straightforward result in both classical and quantized pictures. Such an approach sheds more light on the quantization process and on topics of interest in modern optics.
Young's double-slit experiment demonstrates clearly the propagation of light in the form of a wave motion. Common attempts at a quantized picture of the experiment tend to describe light in terms of the propagation of small spatially localized particles. This is wrong, and unnecessary if quantization of the electric and magnetic field vectors is considered properly. Interference between normal modes of the field is a straightforward result in both classical and quantized pictures. Such an approach sheds more light on the quantization process and on topics of interest in modern optics.
Young's double slit experiment is formulated in the framework of canonical quantum field theory in view of the modern quantum optics. We adopt quantum scalar fields instead of quantum electromagnetic fields ignoring the vector freedom in gauge theory. The double slit state is introduced in Fock space corresponding to experimental setup. As observables, expectation values of energy density and positive frequency part of current with respect to the double slit state are calculated which give the interference term. Classical wave states are realized by coherent double slit states in Fock space which connect quantum particle states with classical wave states systematically. In case of incoherent sources, the interference term vanishes by averaging random phase angles as expected.
The double-slit experiment in quantum mechanics is an experiment devised by physicist Thomas Young. It shows that light has both a wave nature or characteristic and a particle nature or characteristic, and that these natures are inseparable. So light is said to have wave–particle duality rather than be only a wave or only a particle. The same is true of electrons and other quantum particles. Although Christiaan Huygens thought that light was a wave, Isaac Newton did not. Newton felt that there were other explanations for color, and for the interference and diffraction effects that were observable at the time. Owing to Newton’s tremendous stature, his view generally prevailed. The fact that Huygens’s principle worked was not considered evidence that was direct enough to prove that light is a wave. The acceptance of the wave character of light came many years later when, in 1801, the English physicist and physician Thomas Young (1773–1829) did his now-classic double slit experiment
It is well known that the double-slit experiment, under proper conditions, reveals the wave nature of both light and quantum particles like electrons. The wave nature of quantum particles is demonstrated by assuming plane or spherical de Broglie waves to be associated with quantum particles. In this article we deduce the wave nature of material particles starting with proper quantum mechanical amplitudes for propagation as arrived at in the path integral formulation. The classical particle limit of the interference pattern follows right away along the same lines as the corpuscular limit follows from wave optics.
Young’s double slit experiments have been descripted by wave theories, i.e., before and after passing through a double slit, the light is waves. To test the wave description, we extend the double slit experiments to the comprehensive double slit experiments which are the regular double slit experiments with added either Shield, or Blocker, or Metal tube, or Photon-Chamber, or Lens. The comprehensive double slit experiments show the novel phenomena: (1) the light is particles, not waves, before and after passing through a double slit; (2) it is the particles that form both the non-interference patterns (near the double slit) and interference patterns (near/on the detector) in the same experiment; (3) the non-interference patterns gradually evolve to the interference patterns in the same experiment. We refer to the novel phenomena as “PhotoWave phenomena” which are universal. For studying the wave theory further, we show the Irregular-Double-Slit Experiments including the non-parallel-double slit, curve-double-slit, non-parallel-curve-double slit experiments. The comprehensive-double-slit and irregular-double-slit experiments provide the new phenomena for developing theoretical model to study: (1) the nature of the light; (2) the wave theories of the light; (3) the quantum theory of the light. A complete explanation should describe all of the comprehensive double slit and irregular-double-slit experiments consistently, which is a challenge. The experiments presented in this article: (1) show the new mystery of the double slit experiment in addition to Feynman’s mystery; (2) readily performe in the classe room; (3) inexpensive; (4) encourage and stimulate students interest in optics/physics, incorporate hands-on experiments, spark students’ curiosity.
The quantum interference phenomenon was observed in Young’s double-slit experiment using a single photon, and then, the validity of quantum mechanics was demonstrated. However, the reason these fringes appear has not been completely explained yet because photon motion has not been investigated in detail. We found a method to observe the motion of photons using the properties of optical fibers and showed vector diagrams of the photon motion near the double-slit. The photons gradually changed their direction while intersecting and formed interference fringes. In addition, utilizing the mode property of the fiber, we observed fringes at its output end, even when one of the two interfering waves could not transmit through the fiber.
Young’s double slit experiment revived the wave theory of the light. The standard interpretation is that the light behaves as waves before and after passing through the diaphragm of the double slit. Feynman called the double slit experiment the only mystery in quantum mechanics. Recently, the photon chamber has been proposed and utilized to study the behavior of photons near the detecting screen. The experiments show that the light, near the screen, behaves as photons propagating along the straight-line trajectories, and the trajectories distribute as waves. Furthermore, the photon chamber experiments show that, withing a macroscopic distance from the double slit, the pattern is non-interference, which indicates that the standard double slit experiments violate the standard wave interpretations in the area near the diaphragm. In this article, we utilize two new methods to study how the non-interference pattern (near the double slit) evolving to the interference pattern (far from it). The experiments show, the first time, that (1) the shape of the pattern are distance-dependent, when the distance increases, the non-interference pattern evolves to the interference pattern, which indicates that the non-wave nature and the wave distribution coexist in the same wave experiment; (2) the light beams behave as photons near the double slit. The experiments: (1) provide novel phenomena/data for further theoretical development of the established optics and for understanding the nature of the light; (2) show the Feynman’s mystery in the different perspectives; (3) provide three methods that show the non-wave pattern in standard wave experiments and can be utilized to develop the classical optics further.