English: Since its genesis, quantum mechanics has proved to be a very accurate model for predicting the behavior of the world below the nanoscale. However, crucial breakthroughs in technology were needed in order to be able to effectively access and manipulate such small magnitudes. During the last twenty years, the field of quantum information processing has experienced a growing interest, in its many variants, both theoretically and practically. Despite being still at a very basic stage, expectations are high. The uniqueness of quantum phenomena (superposition of states, creation of entanglement, etc.) have no classical analogue and allow novelties such as another paradigm of computation, more secure communications, quantum teleportation, quantum dense coding, etc. which are presented and analyzed here. The aim of this Thesis is to present in a unified way the main mathematical methods used in quantum information processing, as well as the state of the art of their corresponding technological implementations. Our contributions are based in making a self-contained presentation; seeking completeness, that is, treating the most relevant fields of research involved, focusing on their relations; and picking the most relevant, insightful references, given the quantity of literature produced in this field. We also discuss some of the fundamental questions that remain still unanswered, and which are the current lines of research to shed light on them.
English: Since its genesis, quantum mechanics has proved to be a very accurate model for predicting the behavior of the world below the nanoscale. However, crucial breakthroughs in technology were needed in order to be able to effectively access and manipulate such small magnitudes. During the last twenty years, the field of quantum information processing has experienced a growing interest, in its many variants, both theoretically and practically. Despite being still at a very basic stage, expectations are high. The uniqueness of quantum phenomena (superposition of states, creation of entanglement, etc.) have no classical analogue and allow novelties such as another paradigm of computation, more secure communications, quantum teleportation, quantum dense coding, etc. which are presented and analyzed here. The aim of this Thesis is to present in a unified way the main mathematical methods used in quantum information processing, as well as the state of the art of their corresponding technological implementations. Our contributions are based in making a self-contained presentation; seeking completeness, that is, treating the most relevant fields of research involved, focusing on their relations; and picking the most relevant, insightful references, given the quantity of literature produced in this field. We also discuss some of the fundamental questions that remain still unanswered, and which are the current lines of research to shed light on them.
Since its genesis, quantum mechanics has proved to be a very accurate model for predicting the behavior of the world below the nanoscale. However, crucial breakthroughs in technology were needed in order to be able to e ectively access and manipulate such small magnitudes.\nDuring the last twenty years, the eld of quantum information processing has experienced a growing interest, in its many variants, both theoretically and practically. Despite being still at a very basic stage, expectations are high.\nThe uniqueness of quantum phenomena (superposition of states, creation of entanglement, etc.) have no classical analogue and allow novelties such as another paradigm of computation, more secure com-\nmunications, quantum teleportation, quantum dense coding, etc. which are presented and analyzed here. The aim of this Thesis is to present in a uni ed way the main mathematical methods used in quantum\ninformation processing, as well as the state of the art of their corresponding technological implementations.\nOur contributions are based in making a self-contained presentation; seeking completeness, that is,treating the most relevant elds of research involved, focusing on their relations; and picking the most relevant, insightful references, given the quantity of literature produced in this eld. We also discuss some of the fundamental questions that remain still unanswered, and which are the current lines of research to shed light on them.
This book provides a comprehensive and organized study of quantum technology, focusing on principles, mathematical foundations, and practical realizations of quantum teleportation and other processes in the field of quantum information. It starts with the basic principles of quantum mechanics (wave-particle duality, for instance) superposition and measurement theory all helping as the theoretical backbone of current quantum science. In addition to these basics, we provide a concise introduction and discussion of quantum energy or the quantization of energy levels, energy eigenstates and Planck’s constant, which determines what happens in microscopic systems allowing quantum theory an overlap with data from physical observables. Building on these principles, the book introduces quantum states and quantum entanglement, highlighting their non-classical correlations and their crucial role in facilitating quantum communication protocols. This book also discusses quantum gates and quantum circuits as the units of quantum computation and how quantum information is computed and manipulated by using controlled unitary operations. Also, it discusses the impact of both quantum decoherence and environmental noise which pose significant difficulties to coherent quantum systems and dependable information transmission. It discusses methods of error correction and coherence . This book further expanded to quantum cryptography and secure communications with more importance on protocols like quantum key distribution which make use of quantum principles to provide provable security. Quantum computing architectures and algorithms are also measured and various physical implementations and computational models that strive to produce scalable quantum processors are outlined. Problems and limitations of quantum teleportation are critically examined and these are, reliability issues, channel losses, scaling, and resource limitations. Lastly, the book ends by outlining the future of quantum technology, investigating the new technologies and opportunities, the possible advances, and the revolutionary use of quantum technologies in the fields of computation, communication and secure information processing.
Quantum theory and quantum computing in recent years, has raised more and more increasing interest within the scientific community because of various reasons. First, the highly interdisciplinary nature of the subject which involves diverse topics such as, on the theoretical side, information theory and foundational issues of quantum mechanics and on the experimental side, the physics of quantum, optical, atomic and solid state systems. Secondly, the field is extremely promising for revolutionary technological implications in the near future. It is now perfectly clear that one can use quantum mechanics to process and transmit information in a way which does not have a classical analogue, and that using quantum techniques one can implement fully secure cryptographic systems. Recent breakthroughs, such as quantum teleportation, have led to extremely rapid progresses in a fascinating new field and, as a consequence, have attracted the interest of many scientists from varied disciplines. The purpose of this article is to provide a comprehensive overview about the deep involvement of quantum theory in quantum computation to young researchers and newcomers in the field.
Quantum Information Science is a cross-disciplinary subject that has arisen in the last twenty years. It concerns itself with the consequences of our most complete description of the physical world (that is, quantum mechanics) for the reliable, secure, private, and rapid processing of information, both in communication and computation. While its invention is often ascribed to the famous theoretical physicist Richard Feynman in the 1980s, his contributions were only one of many that initiated the field around that time. While he perceived that new types of physical devices, in which the quantum laws of superposition and entanglement function at the logical level, could give new power in the simulation of quantum physics, it was others (Bennett, Brassard) who showed that the uncertainty principle led to fundamentally more secure ways of communicating secret messages. It was yet others (Deutsch, Vazirani) who understood that quantum theory defined a new kind of Turing machine, and that not only quantum physics simulations, but potentially many other computational problems, are sped up in this machine. And it was yet another (Shor) who found a simple, very fast algorithm for prime factorization. The word "qubit" was coined only in 1995. Its introduction is indicative of a new mindset that has developed in recent years for studying and using quantum systems. "Qubit" now stands for a durable paradigm that spans a very wide variety of fields. It thus has many sub-meanings: first, it is the basic abstract unit of information for workers ranging from optical communication engineers to NMR spectroscopists to black-hole theorists. Second, it is the name we now routinely give to physical two level systems, as they are realized by photons, atomic and ionic eigenlevels, electronic and nuclear spin, structural defects in solids, and circulating-current states of superconducting devices. Physics has long dealt with some of these two-level systems, but calling them qubits implies a whole suite of interrelated ideas and capabilities that we ascribe to these systems: the ability to precisely set, and to precisely measure, the quantum state of one unique specimen, to avoid its coupling with the environment while at the same time strongly and controllably coupling the qubits together, to exploit the resulting quantum entanglement as a resource for metrological, cryptographic, and computational tasks. Quantum Information is a very diverse subject pursued today in many different directions, by many hundreds of researchers internationally: In theoretical physics, it has enlivened and sharpened the understanding of efficient representations of entangled many-particle wavefunctions, and has provided the prospect of applications for new concepts such as anyons and majorana fermions. Information theorists has benefitted from having a rigorous extension of the basis of their field, in which classical information theory is subsumed into a greatly broader subject. Theoretical computer scientists continue the search for new quantum algorithms, and have used quantum concepts to prove new results about the classification of computational complexity. Coding theorists have had the new and subtle problem of quantum error correction to analyse and conquer. Most strikingly, the program of experimental physics has been influenced in many directions by Quantum Information Science. State-of-the-art optics experiments transmit quantum states over long distances and perform precision manipulations in single quanta (atomic ions, impurity spins, quantum dots) in the quest to have working quantum cyptography and quantum computing. Quantum Hall systems, and topological insulators, are being assiduously examined for new elementary excitations for use as qubits. In the course of ten years, superconducting devices have improved by over four orders of magnitude in their quantum coherence, a metric made precise by the ideas of quantum computing. [...] DiVincenzo, David
Nowadays quantum information science is in a state of theoretic completeness; much is invested to research quality physical solution for quantum computer and applications, so the field is led by physicists and information science and technology professionals. This field proved its potential and many (including us) believe it is in the right direction to go. In this paper we'll try to present and analyze the philosophy and nature of quantum information science and discuss hot topics around them. Although there is plenty of space for discussion around this field, we will concentrate on some important issues, such as quantum communication, algorithms and cryptography. Communication promises to be one of the directions where huge breakthroughs will be observed (entanglement as communication), algorithms have already shown exponential advantage (Shor's factoring) over classical counterparts and different paradigm of information processing. Cryptography seems to utilize general achievements in quantum information science and make encryption protocols very secure. Quantum computation can be understood as a generalization of classical computation: The possible states of a quantum computer are superpositions of bit strings, where the tensor factor is called a quantum bit or qubit. To evaluate the computational complexity of an algorithm, either classical or quantum, it is necessary to specify a set of elementary operations, the number of which used during the computation quantities the complexity. If we allow arbitrary permutations classically, or arbitrary unitary transformations quantum mechanically, any state can be reached from any other state in a single step. The general kind of quantum computer should be programmed to perform distinctively quantum operations such as generating two bits in a superposition state. An appropriate measurement on the final superposed state of the computer produces a probabilistic behavior of the output, and because of this quantum parallelization does not reduce the average time required for parallelizable computation completion. The development of quantum computing science and technology as well as quantum computers as thinking machines is very dependent on different achievements of modern research in fundamental and applied physics as well as novel mathematical methods and tools.
In the 21st century, the world is full of rapid changes and constant development of technology. The modern rhythm of life requires innovations and revolutionary solutions that would ensure efficiency, safety, and stability in various spheres of activity. In this context, quantum technologies come to the fore and provide unparalleled opportunities to transform our world. The relevance of research and study of quantum technologies is growing every day. They already today have the potential to change our understanding of cleaning processes, cryptography, telecommunications, medicine, and other industries. Understanding the principles of quantum physics and the possibilities of their implementation in practical application becomes necessary due to the rapid progress of scientific research in this area. This research paper aims to review the literature and analyze the prospects and applications of quantum technologies. It will be a valuable source of information for researchers, scientists, engineers, and all those interested in the future development of these advanced technologies. In this framework, the main principles of quantum physics will be developed; its advantages differ from classical technologies and demonstrative application in various fields. Current challenges and obstacles to the introduction of quantum technologies, as well as ways to overcome them, will also be highlighted. It is expected that this work will help readers gain a deeper understanding of the essence of quantum technologies and their impact on the modern world. It will encourage further research, contributing to the development and improvement of these powerful tools.