Modern concepts of the physical phenomenon described by the term “photon”, which was introduced simultaneously with the acceptance of quantum concepts in physics, are presented. Since that time, this term is a necessary component of each discussion about the physical meaning of quantum mechanics. These discussions are generally carried out within the concepts that are 50 or even 100 years old. At the same time, new fields of science have arisen and been developed in the last century: quantum mechanics and quantum electrodynamics, nonlinear optics, theory of dynamic chaos, etc. The experimental potential has been significantly increased, especially when highly coherent lasers were developed. As a result, the difficult problems of quantum mechanics have become aggravated and enriched. In this paper, we discuss two different approaches to gaining insight into the photon nature, which differ radically. An especially urgent problem is the difference in the estimates of the length of light states that are put into correspondence with photons: laser photons are many orders of magnitude longer than the photons put into correspondence with photocounts. Correspondingly, the spectrum of photocounts is many orders of magnitude wider than the lasing spectrum. The author believes that a photocount cannot be put into correspondence with a photon, because the former is a manifestation of the Coulomb nonlinearity of photodetector. The final solution of the question of the photon nature is expected to be obtained experimentally.
Modern concepts of the physical phenomenon described by the term “photon”, which was introduced simultaneously with the acceptance of quantum concepts in physics, are presented. Since that time, this term is a necessary component of each discussion about the physical meaning of quantum mechanics. These discussions are generally carried out within the concepts that are 50 or even 100 years old. At the same time, new fields of science have arisen and been developed in the last century: quantum mechanics and quantum electrodynamics, nonlinear optics, theory of dynamic chaos, etc. The experimental potential has been significantly increased, especially when highly coherent lasers were developed. As a result, the difficult problems of quantum mechanics have become aggravated and enriched. In this paper, we discuss two different approaches to gaining insight into the photon nature, which differ radically. An especially urgent problem is the difference in the estimates of the length of light states that are put into correspondence with photons: laser photons are many orders of magnitude longer than the photons put into correspondence with photocounts. Correspondingly, the spectrum of photocounts is many orders of magnitude wider than the lasing spectrum. The author believes that a photocount cannot be put into correspondence with a photon, because the former is a manifestation of the Coulomb nonlinearity of photodetector. The final solution of the question of the photon nature is expected to be obtained experimentally.
The physical nature of photocounts, i.e. current splashes in outer circuit of receiver at detection of weak optical signals is studied. It is shown, that the basic features of photocounts can be explained if to take into consideration the Coulomb instability of weak electronic flow, appearing in the detector under influence of accepted radiation. Many other particle mani- festations of electrons can be explained by this way. The laser scheme of detection of weak coherent radiation, essentially using laser radiation pumping, is offered. Thereat electrons, bound in atoms, ions or molecules, are used as an active element of device, but not free electrons, as it is usual. The stabilization of electrons by strong Coulomb field of the atom, ion or molecule nuclea does not allow to manifest their Coulomb instability. As a result photocounts, otherwise, Schottky noises are strongly put down at de- tection of weak signals. The detection of light is one of the most fundamental physical processes playing the important role as in nature, so in technique. For example, in na- ture this process provides a possibility of sight and, hence, to know the sur- rounding world. In technique the numerous photodetectors allow to make quantitative the process of detection of optical signals and to expand a spec- trum of accepted radiations.
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.
The nature of electromagnetic (EM) phenomena, including light, is not fully clear. Postulated rejection of EM ether as a hypothetical habitat and distribution of EM waves, holds in the uncertainty and the problem of understanding the existence of most of these waves, because the notion of "wave" inseparable from the concept of "environment". EM ether, as a hypothetical environment of origin and propagation of EM waves, was declined by postulate. This keeps the uncertainty in the problem of understanding the existence of these waves actually, since the definition of "wave" is an part of the definition of "environment". The input in physics of the concept of wave "coherence", which was necessary to explain the phenomenon of interference of light, also requires a transparent physical interpretation. Today use of the idea of the several-meters - length wave zugs, which are emitted by individual atoms, is at least unconvincing, thus there is technical ability to generate powerful light pulses of 10-15 s. A quantum model of the structure of the optical packet stream, which provides a transparent physical interpretation of all parameters of coherent light, is offered. In this model parameters of coherence are organically linked with the geometry parameters of the quantum packets. Developments of classical wave optics will not be discarded. To coordinate with the quantum-packet model and modern views about the nature of light, we either give them a new interpretation or adjust, or develop these developments. In particular, a new interpretation of the experimental fact increase the radius of coherence of light coming from distant sources (stars) is offered. Modern conception of light corpuscles-photons is formulated. The estimations of the size of the spatial localization of the photon is received. "Diffraction of photons" is considered.
Authored by a highly regarded international researcher and pioneer in the field, An Introduction to Quantum Optics: Photon and Biphoton Physics is a straightforward overview of basic principles and experimental evidence for the quantum theory of light. This book introduces and analyzes some of the most exciting experimental research to date in the field of quantum optics and quantum information, helping readers understand the revolutionary changes occurring in optical science. Paints a picture of light in terms of general quantum interference, to reflect the physical truth behind all optical observations Unlike most traditional books on the subject, this one introduces fundamental classical and quantum concepts and measurement techniques naturally and gradually as it explores the process of analyzing typical experimental observations. Separating itself from other books with this uncommon focus on the experimental part of analysis, this volume: Provides a general overview of the optical coherence of light without quantization Introduces concepts and tools of field quantization and quantum optics based on the principles and rules of quantum mechanics Analyzes similarities and differences between classical and quantum coherence Concentrates on key research topics in quantum optics Explains photon and biphoton physics by examining the devices and experimental procedures used to test theories This book is basic enough for students, but it also covers a broad range of higher-level concepts that will benefit scientists and other professionals seeking to enhance their understanding of practical and theoretical aspects and new experimental methods of measurement. This material summarizes exciting developments and observations and then helps readers of all levels apply presented concepts and tools to summarize, analyze, and resolve quantum optical problems in their own work. It is a great aid to improve methods of discovering new physics and better understand and apply nontraditional concepts and interpretations in both new and historical experimental discoveries.
The classical concept of 'physical entity', be it particle, wave, fleld or system, has become a problematic concept since the advent of relativity theory and quantum mechanics. The recent developments in modern quantum mechanics, with the performance of delicate and precise experiments involving single quantum entities, manifesting explicit non-local behavior for these entities, brings essential new information about the nature of the concept of entity. Such fundamental categories as space and time are put into question, and only a recourse to more axiomatic descriptions seems possible. In this contribution we want to put forward a 'picture' of what an 'entity' might be, taking into account these recent experimental and theoretical results, and using fundamental results of the axiomatic physical theories (describing classical as well as quantum entities) such as they have been developed during the last decade. We call our approach the 'creation-discovery view' because it considers measurements as physical interactions that in general entail two aspects: (1) a discovery of an already existing reality and (2) a creation of new aspects of reality during the act of measurement. We analyze the paradoxes of orthodox quantum mechanics in this creation-discovery view and point out the pre-scientiflc preconceptions that are contained in the well-known orthodox interpretations of quantum mechanics. Finally we identify orthodox quantum mechanics as a flrst order non classical theory, and explain in this way why it is so successful in its numerical predictions
The quantum nature of light enables potentially revolutionary communication technologies. A key to advancing this area of research is a clear understanding of the concepts of states, modes, fields, and photons. The concept of field modes carries over from classical optics, while the concept of state has to be considered carefully when treating light quantum mechanically. The term "photon" is an overloaded identifier in the sense that it is often used to refer to either a quantum particle or the state of a field. This overloading, often used without placing it in context, has the potential to obfuscate the physical processes that describe the reality we measure. We review the uses and relationships between these concepts using modern quantum optics theory, including the concept of a photon wave function, the modern history of which was moved forward in a groundbreaking paper in this journal by Iwo Białynicki-Birula, to whom this article is dedicated.