Abstract Entanglement is one of the key properties of the quantum mechanical systems that is fundamentally different from a classical system. Quantum entanglement plays an important role in the debate concerning the foundations of physics but also is an important resource in various quantum information processes. In this article, we introduce basic concepts on EPR correlations and quantum entanglement, and review established entanglement criteria, and show how to use these criteria in the generation of entanglement by considering coherence-induced entanglement and correlated spontaneous emission laser.
Abstract Entanglement is one of the key properties of the quantum mechanical systems that is fundamentally different from a classical system. Quantum entanglement plays an important role in the debate concerning the foundations of physics but also is an important resource in various quantum information processes. In this article, we introduce basic concepts on EPR correlations and quantum entanglement, and review established entanglement criteria, and show how to use these criteria in the generation of entanglement by considering coherence-induced entanglement and correlated spontaneous emission laser.
Quantum entangled states play very important roles in quantum information processing,such as quantum teleportation,dense coding,error correction,cryptography,and computation.The theory of entanglement mainly concerns the characterization of quantum entanglement and the classification of quantum states,as well as its applications in quantum information processing.We present some basic concepts and results,including:the relationship between locality and reality in quantum mechanics and Bell inequalities,and that between Bell inequalities and the separability of quantum states;the definition of separability for pure and mixed quantum states,and some separability criteria such as the positive map approach,positive partial transpose,reduction criterion,realignment,entanglement witnesses,and the covariance matrix approach and local uncertainty relations;some entanglement measures such as the entanglement of formation,concurrence,relative entropy,negativity,tangle,entanglement of assistance,and their estimation;the change in entanglement when the physical system evolves or undergoes interaction with the environment.
Entanglement of quantum is a quantum phenomenon which cannot be described using classical physics. This study reviews the quantum entanglement which discusses the various methods which are used to detect the entanglement. The properties of entanglement in the quantum system have been determined through the theoretical analysis of the quantities of nonclassical measure. That leads to the estimation of quantum entanglement with different parameters conditions. The study of the features and the nature of quantum entanglement enhance our understanding of the nature of entanglement processes. Furthermore, the entanglement is useful in the field of information processing where the entanglement is a basic ingredient of quantum information processing.
Quantum entanglement, the phenomenon whereby two or more quantum systems exhibit correlations that cannot be explained by any local hidden-variable theory, has evolved from a philosophical curiosity debated by Einstein, Podolsky, and Rosen in 1935 into the foundational resource of an emerging technological revolution. This narrative review traces the conceptual development of entanglement from the EPR paradox through Bell's theorem, the experimental violation of Bell inequalities, and the emergence of quantum information science as a unifying framework. Drawing on the original EPR argument, Bell's seminal 1964 theorem, the experimental work of Aspect et al., the quantum information synthesis of Nielsen and Chuang, the review of entanglement theory by Horodecki et al., and the foundational perspectives of Brukner and Zeilinger, the review covers the mathematical characterization of entanglement, its role in quantum computation and quantum cryptography, and the ongoing debate about the interpretation of quantum mechanics that entanglement continues to fuel.
entanglement generated by the far beyond intuitive pure quantum phenomena such as EPRparadox,Schr?dinger's Equation has been considered not only as one of the significant notions in quantum theorybut also a key of realizing the Super Dense Coding and the Quantum Teleportation in quantum communication.However,recent researches show that quantum entanglement is less likely to account for all the properties of quan-tum correlations.Except for the quantum entanglement,researchers find other non-classical correlations like quan-tum discord,which plays a pivotal role in quantum information and quantum computation and that's why the purequbit-decisive quantum computer possesses computational efficiency.With this clarification,quantum discord com-pletely can be a new resource of quantum computation.In this paper,basic notions and measurement methods ofnon- classical correlations(including quantum entanglement) were discussed and the quantum correlationproperties of the quantum discord in various models were analyzed and compared with the quantum entanglement.Conducting researches on the non-classical correlations in various quantum systems are not merely meritorious tothe quantum theory,in the mean time,may provide some efficient thoughts and motivations for researchers to em-ploy theoretical concepts about quantum correlations for avoiding decoherence and theoretical scenario for the exper-iments.
Quantum entanglement is a peculiar phenomenon in quantum information science, characterized by nonclassical correlations between quantum states of subsystems in a quantum system. Since the proposal of the Einstein-Podolsky-Rosen (EPR) paradox by Einstein, Podolsky, and Rosen, quantum entanglement has sparked intense debates on local realism. Bell’s inequality experiment established the nonlocality of quantum mechanics. Currently, high-dimensional quantum entanglement of both deterministic and random states can be realized in systems such as photons and cold atoms. Technologies such as quantum teleportation, quantum teleportation, quantum computing, and others rely on quantum entanglement to achieve effects beyond classical limitations. Current research focuses on the implementation of macroscopic quantum entanglement and its significance in fundamental problems of quantum mechanics. Quantum entanglement opens up a new paradigm for information processing with broad application prospects. It is necessary to conduct in-depth research on the nature of quantum entanglement and its advantages in information processing. This paper reviews the theoretical foundations of quantum entanglement, methods of generation and detection, and research progress in its applications in the field of quantum information. It discusses the important applications of quantum entanglement in quantum communication, computing, and sensing and provides an outlook on the future development prospects of quantum entanglement technologies.
Due to their great importance, both from the fundamental and from the practical points of view, it is imperative that the various facets of the concepts of information and entanglement are explored systematically in connection with diverse physical systems and processes. These concepts are at the core of the emerging field of the Physics of Information. In this Thesis I investigate some aspects of the dynamics of information in both classical and quantum mechanical systems and then move on to explore entanglement in fermion systems by searching for novel ways to classify and quantify entanglement in fermionic systems. In Chapter 1 a brief review of the different information and entropic measures as well as of the main evolution equations of classical dynamical and quantum mechanical systems is given. The conservation of information as a fundamental principle both at the classical and quantum levels, and the implications of Landauer's theorem are discussed in brief. An alternative and more intuitive proof of the no-broadcasting theorem is also provided. Chapter 2 is a background chapter on quantum entanglement, where the differences between the concept of entanglement in systems consisting of distinguishable subsystems and the corresponding concept in systems of identical fermions are emphasized. Different measures of entanglement and relevant techniques such as majorization, are introduced. To illustrate some of the concepts reviewed here I discuss the entanglement properties of an exactly soluble many-body model which was studied in paper (E) of the publication list corresponding to the present Thesis. An alternative approach to the characterization of quantum correlations, based on perturbations under local measurements, is also briefly reviewed. The use of uncertainty relations as entanglement indicators in composite systems having distinguishable subsystems is then examined in some detail. Chapter 3 is based on papers (A) and (B) of the list of publications. Extended Landauer-like principles are developed, based amongst others on the conservation of information of divergenceless dynamical systems. Conservation of information within the framework of general probabilistic theories, which include the classical and quantum mechanical probabilities as particular instances, is explored. Furthermore, Zurek's information transfer theorem and the no-deleting theorem are generalized. Chapter 4 is based on articles (C) and (D) mentioned in the publication list, and investigates several separability criteria for fermions. Criteria for the detection of entanglement are developed based either on the violation of appropriate uncertainty relations or on inequalities involving entropic measures. Chapter 5 introduces an approach for the characterization of quantum correlations (going beyond entanglement) in fermion systems based upon the state disturbances generated by the measurement of local observables. Chapter 6 summarizes the conclusions drawn in the previous chapters. The work leading up to this Thesis has resulted in five publications in peer reviewed science research journals.