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quantum correlation and entropic uncertainty in a quantum-dot system

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Chinese Physics B 2022年第10期31卷 314-318页

作者： Ying-Yue Yang Li-Juan Li Liu Ye Dong Wang School of Physics and Optoelectronic Engineering Anhui UniversityHefei 230601China

We explore the dynamical behaviors of the measurement uncertainty and quantum correlation for a vertical quantumdot system in the presence of magnetic field, including electron-electron interaction and Coulomb-blocked systems. Stemming from the quantum-memory-assisted entropic uncertainty relation, the uncertainty of interest is associated with temperature and parameters related to the magnetic field. Interestingly, the temperature has two kinds of influences on the variation of measurement uncertainty with respect to the magnetic-field-related parameters. We also discuss the relation between the lower bound of Berta et al. and the quantum discord. It is found that there is a natural competition between the quantum discord and the entropy min_(Π~B_(i)) SΠ~B_(i)(ρ_(A|B)). Finally, we bring in two improved bounds to offer a more precise limit to the entropic uncertainty.

关键词： entropic uncertainty relation quantum correlation quantum dot

Monogamy quantum correlation near the quantum phase transitions in the two-dimensional XY spin systems

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Chinese Physics B 2018年第6期27卷 137-144页

作者： Meng Qin Zhongzhou Ren Xin Zhang Department of General Education Army Engineering University of PLA Nanjing 211101 China Department of Physics Nanfing University Nanjing 210093 China School of Physics Science and Engineering Tongji University Shanghai 200092 China

We investigate the role of quantum correlation around the quantum phase transitions by using quantum renormalization group theory. Numerical analysis indicates that quantum correlation as well as quantum nonlocality can efficiently detect the quantum critical point in the two-dimensional XY systems. The nonanalytic behavior of the first derivative of quantum correlation is observed at the critical point as the size of the model increases. Furthermore, we discuss the quantum correlation distribution in this system based on the square of concurrence（SC） and square of quantum discord（SQD）. The monogamous properties of SC and SQD are obtained. Particularly, we prove that the quantum critical point can also be achieved by monogamy score.

关键词： XY model quantum phase transitions quantum correlation monogamy relation

Investigations into quantum correlation of coupled qubits in a squeezed vacuum reservoir

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Chinese Physics B 2013年第2期22卷 86-91页

作者：嵇英华刘咏梅 Department of Physics Jiangxi Normal University Key Laboratory of Photoelectronics and Telecommunication of Jiangxi Province College of Mathematics and Information Science Jiangxi Normal University

In this paper,we investigate the quantum correlation of coupled qubits which are initially in maximally entangled mixed states in a squeezed vacuum *** compare and analyze the effects of squeezed parameters on quantum discord and quantum *** results show that in a squeezed vacuum reservoir,the quantum discord and quantum concurrence perform with completely opposite behaviors with the change of squeezed *** discord survives longer with the increase of squeezed amplitude parameter,but entanglement death is faster on the *** results also indicate that the classical correlation of the system is smaller than quantum discord in a vacuum reservoir,while it is bigger than quantum discord in a squeezed vacuum *** quantum discord and classical correlation are more robust than quantum concurrence in the two reservoir environments,which indicates that the entanglement actually is easily affected by decoherence and quantum discord has a stronger ability to avoid decoherence in a squeezed vacuum reservoir.

关键词： quantum correlation coupled qubits quantum discord concurrence

von Neumann measurement-related matrices and the nullity condition for quantum correlation

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Science China(Physics,Mechanics & Astronomy) 2016年第12期59卷 27-32页

作者： MingJing Zhao Teng Ma TingGui Zhang Shao-Ming Fei School of Science Beijing Information Science and Technology UniversityBeijing 100192China State Key Laboratory of Low-Dimensional quantum Physics and Department of Physics Tsinghua UniversityBeijing 100084China School of Mathematics and Statistics Hainan Normal UniversityHaikou 571158China School of Mathematical Sciences Capital Normal UniversityBeijing 100048China Max-Planck-Institute for Mathematics in the Sciences Leipzig 04103Germany

We study von Neumann measurement-related matrices, and the nullity condition of quantum correlation. We investigate the properties of these matrices that are related to a von Neumann measurement. It is shown that these(m^2-1)×(m^2-1) matrices are idempotent, and have rank m-1. These properties give rise to necessary conditions for the nullity of quantum correlations in bipartite systems. Finally, as an example we discuss quantum correlation in Bell diagonal states.

关键词： von Neumann measurement matrix rank quantum correlation

Optimizing quantum correlation dynamics by weak measurement in dissipative environment

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Chinese Physics B 2015年第4期24卷 221-226页

作者：杜少将夏云杰段德洋张路高强 Shandong Provincial Key Laboratory of Laser Polarization and Information Technology Department of PhysicsQufu Normal University Department of Physics and Information Engineering Jining University

We investigate the protection of quantum correlations of two qubits in independent vacuum reservoirs by means of weak measurements. It is found that the weak measurement can reduce the amount of quantum correlation for one type of initial state at the beginning in a non-Markovian environment and meanwhile it can reduce the occurrence time of entanglement sudden death （ESD） in the process of time evolution. In a Markovian environment, the quantum entanglements of the two kinds of initial states decay rapidly and the weak measurement can further weaken the quantum entanglement, therefore in this case the entanglement cannot be optimized in the evolution process.

关键词： quantum entanglement quantum correlation entanglement sudden death weak measurement

Research on the Freezing Phenomenon of quantum correlation by Machine Learning

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Computers, Materials & Continua 2020年第12期65卷 2143-2151页

作者： Xiaoyu Li Qinsheng Zhu Yiming Huang Yong Hu Qingyu Meng Chenjing Su Qing Yang Shaoyi Wu Xusheng Liu School of Information and Software Engineering University of Electronic Science and Technology of ChinaChengdu610054China School of Physics University of Electronic Science and Technology of ChinaChengdu610054China Department of Chemistry and Biochemistry Utah State UniversityLoganUtah84322USA

quantum correlation shows a fascinating nature of quantum mechanics and plays an important role in some physics topics,especially in the field of quantum *** correlations of the composite system can be quantified by resorting to geometric or entropy methods,and all these quantification methods exhibit the peculiar freezing *** challenge is to find the characteristics of the quantum states that generate the freezing phenomenon,rather than only study the conditions which generate this phenomenon under a certain quantum *** essence,this is a classification *** learning has become an effective method for researchers to study classification and feature *** this work,we prove that the machine learning can solve the problem of X form quantum states,which is a problem of physical ***,we apply the density-based spatial clustering of applications with noise(DBSCAN)algorithm and the decision tree to divide quantum states into two different *** goal is to classify the quantum correlations of quantum states into two classes:one is the quantum correlation with freezing phenomenon for both Rènyi discord(α=2)and the geometric discord(Bures distance),the other is the quantum correlation of non-freezing *** results demonstrate that the machine learning method has reasonable performance in quantum correlation research.

关键词： Machine learning quantum correlation freezing phenomenon Rènyi discord geometric discord

The Controllability of quantum correlation under Geometry and Entropy Discords

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Computers, Materials & Continua 2021年第3期66卷 3107-3120页

作者： Xiaoyu Li Yiming Huang Qinsheng Zhu Xusheng Liu Desheng Zheng School of Information and Software Engineering University of Electronic Science and Technology of ChinaChengdu610054China School of Physics University of Electronic Science and Technology of ChinaChengdu610054China Department of Chemistry and Biochemistry Utah State UniversityLoganUtah84322USA School of Computer Science Southwest Petroleum UniversityChengdu610000China

quantum correlation plays a critical role in the maintenance of quantum information processing and nanometer device *** the past two decades,several quantitative methods had been proposed to study the quantum correlation of certain open quantum systems,including the geometry and entropy style discord ***,there are differences among these quantification methods,which promote a deep understanding of the quantum *** this paper,a novel time-dependent three environmental open system model is established to study the quantum *** system model interacts with two independent spin-environments(two spin-environments are connected to the other spin-environment)*** have calculated and compared the changing properties of the quantum correlation under three kinds of geometry and two entropy discords,especially for the freezing *** the same time,some original and novel changing behaviors of the quantum correlation under different timedependent parameters are studied,which is helpful to achieve the optimal revival of the quantum discord and the similar serrated form of the freezing ***,it shows the controllability of the freezing correlation and the robustness of these methods by adjusting time-dependent *** work provides a new way to control the quantum correlation and design nanospintronic devices.

关键词： Spin environment quantum correlation nanospintronic devices quantum information freezing phenomenon

Measurement of strong phases, D-D mixing, and CP violation using quantum correlation at charm threshold

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Frontiers of physics 2016年第1期11卷 1-15页

作者： Matteo Rama Sezione di Pisa dell'Istituto Nazionale di Fisica Nucleate Pisa Italy

We review the measurements of the D decay strong-phase parameters based on quantum-correlated D^0D^-0 pairs produced in the e^＋e^→（3770） →D^0D^-0 process, and we discuss their role in the measurements of Cabibbo-Kobayashi-Maskawa angle 7 and D-/9 mixing. In addition, we present estimates of the size of quantum-correlated datasets necessary to support the 7 and charm mixing measurements conducted at the LHCb and Belle Ⅱ experiments. Finally, we review the methods for measuring the D-D^- mixing and cP violation parameters at a high-luminosity charm factory, giving sensitivity estimates.

关键词： quantum correlation charm mixing CP violation

The uncertainty and quantum correlation of measurement in double quantum-dot systems

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Frontiers of physics 2022年第6期17卷 211-218页

作者： Long-Yu Cheng Fei Ming Fa Zhao Liu Ye Dong Wang School of Physics and Optoelectronic Engineering Anhui UniversityHefei 230601China CAS Key Laboratory of quantum Information University of Science and Technology of ChinaHefei 230026China

In this work,we study the entropic uncertainty and quantum discord in two double-quantum-dot(DQD)system coupled via a transmission line resonator(TLR).Explicitly,the dynamics of the systemic quantum correlation and measured uncertainty are analysed with respect to a general Xtype state as the initial ***,it is found that the different parameters,including the eigenvalueαof the coherent state,detuning amountδ,frequencyωand the coupling constant g,have subtle effects on the dynamics of the entropic uncertainty,such as the oscillation period of the *** is clear to reveal that the quantum discord and the lower bound of the entropic uncertainty are anti-correlated when the initial state of the system is the Werner-type state,while quantum discord and the lower bound of the entropic uncertainty are not anti-correlated when the initial state of the system is the Bell-diagonal ***,we claim that the current investigation would provide an insight into the entropic uncertainty and quantum correlation in DQDs system,and are basically of importance to quantum precision measurement in practical quantum information processing.

关键词： uncertainty relations quantum correlation quantum dot