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.
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.
Quantum optics is the branch of physics that investigates the interaction of light with matter at the quantum level, where the discrete nature of photons and quantum states of atoms, molecules, and solid-state systems become dominant. Quantum optics systems provide the experimental and theoretical foundation for understanding nonclassical states of light, quantum coherence, entanglement, and measurement at the quantum limit. Over the past few decades, advances in laser technology, nonlinear optics, and precision measurement have transformed quantum optics from a fundamental discipline into a key enabler of quantum technologies, including quantum communication, quantum computing, quantum sensing, and quantum metrology. This review presents a comprehensive overview of the physical principles, system architectures, and experimental platforms of quantum optics. Emphasis is placed on light sources, atom–photon interaction systems, detection techniques, and emerging applications, along with current challenges and future research directions.
The centrality of the photon concept in modern physics is strongly evident in wide spheres of photonics and nanophotonics. Despite the resilience and persistence of earlier classical representations, there are numerous optical features and phenomena that only truly photon-based descriptions of theory can properly address. It is crucial to cast theory in terms of observables, and in this respect the quantum theory of light engages most directly and pragmatically with experiment. No other theory adequately reconciles the discreteness in energy of optical quanta, with their characteristic quantum mechanical delocalization in space. Examples of the distinctiveness of a photonic representation are to be found in nonclassical optical correlations; intensity fluctuations and phase; polarization, spin, and information content; measures of optical chirality; near-field interactions; and plasmonics. Increasingly, links between these fundamental properties and features are proving significant in the context of nanoscale interactions. Yet, even as new technologies are being built on the framework of modern photonics, a number of difficult questions surrounding the nature of the photon still remain. Both in its flourishing applications and in matters of fundamental entity, the photon is still a subject very much at the heart of current research.
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.
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.
This book provides an overview of quantum light phenomena and extends the traditional Quantum Optics, to include quantum fluids of light and the complete electromagnetic vacuum. The first part of the book includes basic electromagnetic field quantisation, the characterisation of quantum photon states and elementary photon–atom interactions. Secondly, quantum fluids of light are explored such as recent areas as Bose–Einstein condensation, light vortices and superfluid light. Finally, the last section of the book focusses on a more complete description of quantum vacuum, which includes electron–positron states. The book is intended to make the bridge between these three somewhat distinct aspects of the quantum states of light. The main audiences for the book include researchers and advanced students in quantum technology including quantum optics, metrology and computing. Part of IOP Series in Quantum Technology. Key features • Up to date review of the field, including quantum fluids of light • Extensive coverage of the topic • Key and central theme for modern quantum science and technology • Written by a respected expert in the field
In the mid-18th century, Isaac Newton regarded light as some extremely small particles. Based on this, Newton established the particle theory of light. In the mid-19th century, Huygens and Augustine Jean Fresnel conducted extensive research on light and concluded that light is a wave. Afterwards, Maxwell proposed the theory of electromagnetism. Maxwell believed that light is a wave with a wavelength within a limited range. With the establishment of Maxwell's equation electromagnetic wave theory, the wave nature of light began to dominate the mainstream consciousness; However, in the late 19th century, a series of experimental phenomena represented by the photoelectric effect could not be accurately explained by the wave theory of light. In 1905, Einstein proposed the concept of light quanta and successfully explained the photoelectric effect. While perfectly explaining these issues, a new question arises: what is the essence of light, given that both particle and wave properties can accurately reflect certain properties of light? It has always been the most fiercely debated issue in the history of optics. Einstein said that we are not yet clear about what light quanta are, and wave particle duality cannot fully explain optical phenomena. Based on the study of Albert Einstein's concept of quanta light, wave particle duality of light, string theory, and optical frequency combs, the author proposes the concept of lightstring, attempting to propose new ideas for studying the essence of light and its generation mechanism. Siwen Bi has been researching quantum remote sensing since March 2000 and quantum spectral imaging since June 2003, but has encountered some difficulties and problems. What is the basic theory of passive imaging in quantum remote sensing? How is technology implemented? What is the fundamental theory of quantum spectroscopy? The Implementation Technology of Quantum Optical Field Entangled States in Long Distance Quantum Detection Process? These difficulties and questions prompt the author of this article to contemplate and study the essence of light? What is the fundamental theory of the future technology of quantum optics? Siwen Bi conducted exploratory research on the nature of light in 2006. This article first provides an overview of the development history and research status of optics and describes the difficulties and shortcomings in fully explaining optical phenomena due to the wave particle duality of light quantum and light; Then, two inspiring viewpoints on optical frequency comb and chord theory were introduced. On this basis, the basic concept of optical string (optical frequency string), the prototype description of optical string, the mechanism of optical string generation, and the discussion of Lightstring, generation process are proposed and emphasized; Proposed the mechanism of string light effect. Published On Two Heuristic Viewpoints Concerning the Study of Light (October 13-15, 2014), New Viewpoints In Light Quantum Research: Lightstring (2016), Discuss wave-particle duality of light, (February 28, 2017), and an Exploratory research on the light quantum future technical basis (February 1, 2019). Over the past 17 years, achieved some original and innovative research results. some original innovative research achievements have been achieved. Received high praise from international scholars and professors, such as the American Journal of Physics and Applications, which sent me a congratulatory letter saying, "Dear Bi Siwen, Warmest greeting from the Editorial Department! It is reported that at the International conference on photo and optical Engineering (ICPOE 2014), a paper entitled" Two Enlightening Views on Optical Research "was published, and the theme of the paper impressed us deeply. It has attracted the attention of Photon researchers and Scholars ...Your research is highly appreciated by us … " And invite Professor Bi Siwen as a paper reviewer for the American Journal of Physics and Applications. I have received the paper review certificate, dated May 25th, 2018. Based on the above research, Siwen Bi elaborated on the geometric and kinematic characteristics of Lightstring, and proposed the essence of light based on the concept of Lightstring, in order to concretize the concept of light quanta. On this basis, the mechanism of string light effect based on the concept of optical string is proposed. An attempt has been made to further study the quantum and wave particle duality of light, gain a profound understanding of the nature of light, and answer the question "What is light?" by proposing a new approach and method for studying the nature of light and its generation mechanism. Proposed a study on optical quantum; The wave particle duality of light; New ideas, methods, and perspectives on the mechanism of light generation.