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Quantum coherence and quantum correlations are of fundamental and practical significance for the development of quantum mechanics.They are also cornerstones of quantum computation and quantum communication theory. Searching physically…

Quantum Physics · Physics 2018-12-18 Ming-Liang Hu , Xueyuan Hu , Jie-Ci Wang , Yi Peng , Yu-Ran Zhang , Heng Fan

We consider the classical correlations that two observers can extract by measurements on a bipartite quantum state, and we discuss how they are related to the quantum mutual information of the state. We show with several examples how…

Quantum Physics · Physics 2009-09-19 Shengjun Wu , Uffe V. Poulsen , Klaus Mølmer

Measurements with randomly chosen settings determine many important properties of quantum states without the need for a shared reference frame or calibration. They naturally emerge in the context of quantum communication and quantum…

Let us consider the set of joint quantum correlations arising from two-outcome local measurements on a bipartite quantum system. We prove that no finite dimension is sufficient to generate all these sets. We approach the problem in two…

Quantum Physics · Physics 2013-05-29 T. Vértesi , K. F. Pál

We propose a modified metric based on the Hilbert-Schmidt norm and adopt it to define a rescaled version of the geometric measure of quantum discord. Such a measure is found not to suffer from the pathological dependence on state purity.…

Quantum Physics · Physics 2013-06-21 Tommaso Tufarelli , Tom MacLean , Davide Girolami , Ruggero Vasile , Gerardo Adesso

Quantum mechanics predicts that measurements of incompatible observables carry a minimum uncertainty which is independent of technical deficiencies of the measurement apparatus or incomplete knowledge of the state of the system. Nothing yet…

Quantum Physics · Physics 2013-06-14 Davide Girolami , Tommaso Tufarelli , Gerardo Adesso

A symmetric measure of quantum correlation based on the Hilbert-Schmidt distance is presented in this paper. For two-qubit states, we simplify considerably the optimization procedure so that numerical evaluation can be performed…

Quantum Physics · Physics 2011-07-18 Mingjun Shi , Fengjian Jiang , Jiangfeng Du

Quantum correlations between parts of a composite system most clearly reveal themselves through entanglement. Designing, maintaining, and controlling entangled systems is very demanding, which raises the stakes for understanding the…

Quantum Physics · Physics 2019-08-21 Matthew A. Hunt , Igor V. Lerner , Igor V. Yurkevich , Yuval Gefen

Quantum correlation provides a promising measure beyond entanglement. Here, we propose a necessary and sufficient condition for nonzero quantum correlation in continuous variable systems, which is simple and easy to perform in terms of a…

Quantum Physics · Physics 2015-11-12 Chengjie Zhang , Sixia Yu , Qing Chen , Haidong Yuan , C. H. Lai , C. H. Oh

The characterization of quantum correlations is crucial to the development of new quantum technologies and to understand how dramatically quantum theory departs from classical physics. Here we systematically study single- and multiparticle…

Quantum Physics · Physics 2020-06-05 Rejane Alves de Brito , Bertúlio de Lima Bernardo

Consider a scenario where $N$ separated quantum systems are measured, each with one among two possible dichotomic observables. Assume that the $N$ events corresponding to the choice and performance of the measurement in each site are…

Quantum Physics · Physics 2007-05-23 Ll. Masanes

The quantumness of the correlation known as quantum correlation is usually measured by quantum discord. So far various quantum discords can be roughly understood as indirect measure by some special discrepancy of two quantities. We present…

Quantum Physics · Physics 2015-06-16 Chang-shui Yu , Heng Fan

The recently established resource theory of quantum coherence allows for a quantitative understanding of the superposition principle, with applications reaching from quantum computing to quantum biology. While different quantifiers of…

The entanglement detection via local measurements can be experimentally implemented. Based on mutually unbiased measurements and general symmetric informationally complete positive-operator-valued measures, we present separability criteria…

Quantum Physics · Physics 2018-03-30 Shu-Qian Shen , Ming Li , Xianqing Li-Jost , Shao-Ming Fei

By quantum calibration we name an experimental procedure apt to completely characterize an unknown measurement apparatus by comparing it with other calibrated apparatuses. Here we show how to achieve the calibration of an arbitrary…

Quantum Physics · Physics 2007-05-23 Giacomo Mauro D'Ariano , Lorenzo Maccone , Paoloplacido Lo Presti

Quantum information theory has considerably helped in the understanding of quantum many-body systems. The role of quantum correlations and in particular, bipartite entanglement, has become crucial to characterise, classify and simulate…

Quantum Physics · Physics 2018-07-27 Gabriele De Chiara , Anna Sanpera

We introduce an algebraic measure of correlations in bipartite quantum systems. The proposed quantity, called maximal mutual correlation, provides the information how much a given state differs from the product state of its marginals. In…

Quantum Physics · Physics 2016-07-25 Lech Jakobczyk

An essential feature of genuine quantum correlation is the simultaneous existence of correlation in complementary bases. We reveal this feature of quantum correlation by defining measures based on invariance under a basis change. For a…

Quantum Physics · Physics 2014-02-11 Shengjun Wu , Zhihao Ma , Zhihua Chen , Sixia Yu

Quantum metrology based on quantum entanglement and quantum coherence improves the accuracy of measurement. In this paper, we briefly review the schemes of quantum metrology in various complex systems, including non-Markovian noise,…

Quantum Physics · Physics 2024-01-18 Qing Ai , Yang-Yang Wang , Jing Qiu

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…