Quantum Theory in the Light of Modern Experiments

Charles Paul Enz

Azeddine Messikh, Youssouf Hamidou Issoufa

Quantum optics was born in the first years of the 20th century. The first papers leading to further ideas of quanta of light were presented by Max Planck and Albert Einstein. Their pioneering papers laid the foundations for the theory of quantum optics. However, one should remember that for the birth of the formal theory of quantisation of light, the development of quantum mechanics was necessary. Interestingly, the word ’photon’ appeared for the first time in a paper by a Gilbert Lewis, a chemist, in 1926 and was later used by P.A.M. Dirac, a physicist, the next year. The modern sense of the term quantum optics was established in 1956 when Hanbury Brown and Twiss built the intensity interferometr and performed their famous experiment in which correlations between two light beams were measured. Although the results of their experiment could be explained on the basis of the classical theory of light, with some quantumcomponent to the process of photodetection, their result is commonly accepted as the beginning of the modern quantum optics era. The next milestone in the development of quantum optics was the invention of laser in 1960. The physical properties of the light generated by lasers were considerably different from those characterising the light generated by classical thermal sources. This fact was a great impulse leading to further development of quantum optics’ ideas. The first of them were presented in the fundamental papers written by Glauber, describing new states of light quantum coherent states.

Ted Bastin

Massimiliano Malgieri, Antonio Tenni, Pasquale Onorato +1 more

Abstract In this paper we present a reasoning line for introducing the Pauli exclusion principle in the context of an introductory course on quantum theory based on the sum over paths approach. We start from the argument originally introduced by Feynman in ‘ QED: The Strange Theory of Light and Matter ’ and improve it by discussing with students modern experimental evidence from the famous Hong–Ou–Mandel experiment with indistinguishable photons and its generalised version using electrons. The experiments can be analysed in a rather simple way using Feynman’s method of ‘arrow multiplication’ for treating processes involving more than one quantum object. The approach described is especially relevant in the formation of high school physics teachers to the basics of modern physics.

Louis de Broglie

Madiha, P. Bindal, R. Kumar +1 more

In this paper, we study single slit and double slit diffraction using theory, experiment and simulation. The aim of this study is to understand the behaviour of light subjected to different conditions and also try to relate it with the concept of Maya from Indian philosophy. In the experiments, sodium light is used to observe diffraction patterns. We also study how different parameters like slit width, wavelength, intensity and distance between slits influence the pattern. The results show that light behaves like a wave in diffraction. In quantum mechanics experiments, it also behaves like a particle when observed. This idea is compared with the concept of Maya, where reality depends on observation. The study shows that there is some similarity between modern physics and ancient Indian philosophy.