Experimental test of the quantum violation of the noncontextuality inequalities for the n-cycle scenario (original) (raw)

Use of quantum correlation: A theoretical and experimental perspective

Journal of the Indian Institute of …, 2009

| Recent interest in the field of quantum information processing has given rise to a flurry of theoretical as well as experimental activity, on entanglement, a purely quantum mechanical phenomenon. We briefly review quantification of entanglement and its use in carrying out quantum tasks like teleportation. The measures are primarily concerned with bipartite entanglement. Systems such as spin chains and quantum dots have been identified to execute some of these quantum protocols. Experimental realization of quantum networks, especially in the form of spin chains, has been dealt here, along with methods to extract the content of entanglement from experimental data. We explicate the effect of environment on quantum networks and how to extract quantum information before the system decoheres.

Correlation properties of quantum measurements

1996

Abstract: The kind of information provided by a measurement is determined in terms of the correlation established between observables of the apparatus and the measured system. Using the framework of quantum measurement theory, necessary and sufficient conditions for a measurement interaction to produce strong correlations are given and are found to be related to properties of the final object and apparatus states. These general results are illustrated with reference to the standard model of the quantum theory of measurement.

Quantum Correlations Bell's Theorem

Quantum theory predicts the existence of so-called tripartite-entangled states, in which three quantum particles are related in a way that has no counterpart in classical physics. [48] Physicists from Swansea University are part of an international research collaboration which has identified a new technique for testing the quality of quantum correlations. [47] These insights may prove useful for the development of future theories unifying quantum mechanics and gravity." [46] Physicists at the University of Innsbruck are proposing a new model that could demonstrate the supremacy of quantum computers over classical supercomputers in solving optimization problems. [45] Using data from the CMS experiment there, the researchers studied the entropy resulting from entanglement within the proton. [44]

Dual quantum-correlation paradigms exhibit opposite statistical-mechanical properties

Physical Review A, 2012

We report opposite statistical mechanical behaviors of the two major paradigms in which quantum correlation measures are defined, viz., the entanglement-separability paradigm and the informationtheoretic one. We show this by considering the ergodic properties of such quantum correlation measures in transverse quantum XY spin-1 2 systems in low dimensions. While entanglement measures are ergodic in such models, the quantum correlation measures defined from an information-theoretic perspective can be nonergodic.

Criteria for measures of quantum correlations

2012

Entanglement does not describe all quantum correlations and several authors have shown the need to go beyond entanglement when dealing with mixed states. Various different measures have sprung up in the literature, for a variety of reasons, to describe bipartite and multipartite quantum correlations; some are known under the collective name quantum discord. Yet, in the same sprit as the criteria for entanglement measures, there is no general mechanism that determines whether a measure of quantum and classical correlations is a proper measure of correlations. This is partially due to the fact that the answer is a bit muddy. In this article we attempt tackle this muddy topic by writing down several criteria for a "good" measure of correlations. We breakup our list into necessary, reasonable, and debatable conditions. We then proceed to prove several of these conditions for generalized measures of quantum correlations. However, not all conditions are met by all measures; we show this via several examples. The reasonable conditions are related to continuity of correlations, which has not been previously discussed. Continuity is an important quality if one wants to probe quantum correlations in the laboratory. We show that most types of quantum discord are continuous but none are continuous with respect to the measurement basis used for optimization.

On Explaining Non-dynamically the Quantum Correlations Via Quantum Information Theory: What It Takes

Philosophy of Engineering and Technology, 2018

In this paper, we argue that quantum information theory can provide a kind of non-causal explanation ("causal account" here stands quite generally both for dynamical and for mechanistic account of causal explanation) of quantum entanglement. However, such an explanation per se does not rule out the possibility of a dynamical explanation of the quantum correlations, to be given in terms of some interpretations (or alternative formulations) of quantum theory. In order to strengthen the claim that it can provide an explanation of the quantum correlations, quantum information theory should inquire into the possibility that the quantum correlations could be treated as "natural", that is, as phenomena that are physically fundamental. As such, they would admit only a structural explanation, similarly to what happened in crucial revolutionary episodes in the history of physics.

Experimentally Witnessing the Quantumness of Correlations

2011

The quantification of quantum correlations (other than entanglement) usually entails laboured numerical optimization procedures also demanding quantum state tomographic methods. Thus it is interesting to have a laboratory friendly witness for the nature of correlations. In this Letter we report a direct experimental implementation of such a witness in a room temperature nuclear magnetic resonance system. In our experiment the nature of correlations is revealed by performing only few local magnetization measurements. We also compare the witness results with those for the symmetric quantum discord and we obtained a fairly good agreement.

Unified View of Quantum and Classical Correlations

Physical Review Letters, 2010

We discuss the problem of separation of total correlations in a given quantum state into entanglement, dissonance, and classical correlations using the concept of relative entropy as a distance measure of correlations. This allows us to put all correlations on an equal footing. Entanglement and dissonance, whose definition is introduced here, jointly belong to what is known as quantum discord. Our methods are completely applicable for multipartite systems of arbitrary dimensions. We investigate additivity relations between different correlations and show that dissonance may be present in pure multipartite states.

Lectures on General Quantum Correlations and their Applications

Quantum Science and Technology, 2017

Monogamy is an intrinsic feature of quantum correlations that gives rise to several interesting quantum characteristics which are not amenable to classical explanations. The monogamy property imposes physical restrictions on unconditional sharability of quantum correlations between the different parts of a multipartite quantum system, and thus has a direct bearing on the cooperative properties of states of multiparty systems, including large many-body systems. On the contrary, a certain party can be maximally classical correlated with an arbitrary number of parties in a multiparty system. In recent years, the monogamy property of quantum correlations has been applied to understand several key aspects of quantum physics, including distribution of quantum resources, security in quantum communication, critical phenomena, and quantum biology. In this chapter, we look at some of the salient developments and applications in quantum physics that have been closely associated with the monogamy of quantum discord, and "discord-like" quantum correlation measures.