In this paper the authors discuss recent advances and trends in laser spectroscopy and quantum optics. It is obvious that both are fields that experienced a tremendous development in the last twenty years. Therefore the survey must be incomplete, and only a few highlights are touched on.
The field of quantum optics has progressed rapidly in the last twenty five years with the advent of the laser. Over much of this period the phenomena studied could be described adequately by semiclassical treatments. Quite recently however, there has been a revival of interest in genuinely quantum mechanical effects. The Malvern Symposium of December 1985 brought together world experts for a meeting which concentrated largely on these quantum effects. The presentations in this unique meeting combine review material with the very latest results and so will be of value to students of quantum optics and measurement theory at all levels. The first articles cover the exciting topic of the generation of squeezed states of light in the laboratory, and their possible uses. Experimental success has been long sought and very recently attained. The reader will find presented the state of the art in this field. Next to lasing itself, optical bistability has been the most widely studied phenomenon in quantum optics, largely for its technological promise. However, it also provides a fundamental system to study quuantum effects. Recent theoretical studies of optical bistability with small numbers of atoms are surveyed. In such situations quantum features such as antibunching become significant, and the articles in this volume should be a guide to those venturing into this challenging area. In other articles discussions of fluctuations from other noise sources and instabilities in optical bistabilty are presented in a clear and interesting way. Perhaps the least classical state on quantum optics is that describing a single photon. Recent experiments which produce such states are reviewed. A theoretical review of the photon together with some new material is given which delves deeply into relativistic quantum field theory in order to describe the concept of weakly localised photon states. The material here is very rarely presented in the context of quantum optics. The history of the theory of the quantum fluctuations in a laser is then reviewed. An off-shoot of this theory is the study of quantum chaos in dissipative systems and recent results in this new area are given in a succeeding article. There are further stimulating articles on Rydberg atom systems and quantum electrodynamics. The volume ends with an entertaining and incisive study of quantum measurement problems, such as the Schrodinger cat papadox, using concepts and measuring devices found in quantum optics.other_titles
This text includes all the recent advances in the field of laser spectroscopy. Major results span from the control of matter by electromagnetic fields (trapping and coding) to high precision measurements on simple atomic systems and to quantum optics with single atoms. It includes a report of the Bose-Einstein condensation achieved by laser-cooling of rubidium atoms. Achievements in the technology of tunable sources, in particular of miniaturized solid state devices, are also reported. Most recent advances in molecular spectroscopy are illustrated with emphasis on cooled spectra, clusters and high accuracy frequency references. Topics such as atomic interferometry and microcavity quantum optics are also covered.
Quantum computing, in the last few years, has made tremendous gains both scientifically and commercially. The recent announcements by Google and Microsoft on new qubit implementation approaches, addressing scaling and error correction, forecast the superior capability of quantum computing over classical computing in various application domains. One area that has seen significant advancements in research is the application of quantum algorithms in machine learning, giving rise to the exciting field of quantum machine learning. Therefore, the essence of this paper is to survey the recent advancements in quantum machine learning. The survey primarily focuses on hybrid quantum machine learning, with a particular emphasis on recent research advancements in the application of variational quantum algorithms and data encoding for quantum machine learning. The paper discusses the use of variational quantum algorithms in classification and regression tasks. In classification, recent work in image, speech, and text classification is discussed, highlighting the advances and limitations. In the case of regression, recent research work in single and multi-dimensional regressions is discussed. This survey aims to cover the application of variational quantum algorithms in enhancing the capabilities of hybrid quantum machine learning.