Entanglement of General Two-Qubit States in a Realistic Framework

In the present paper, we examine the quantum entanglement for more general states of two-qubit system in the context of spin coherent states (SCSs). We consider the concurrence as a quantifier of entanglement and express it in terms of SCSs. We determine new set of maximally entangled conditions that provide the maximal amount of entanglement for certain values of the amplitudes of SCSs for the case of pure states. Finally, we examine the entanglement of a class of mixed states of the two qubits and provide the range in which the entanglement value is maximal with respect to the values of the amplitudes of SCSs.

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A COMPARATIVE STUDY OF NEGATIVITY AND CONCURRENCE BASED ON SPIN COHERENT STATES

International Journal of Modern Physics C ◽

10.1142/s0129183110015129 ◽

2010 ◽

Vol 21 (03) ◽

pp. 291-305 ◽

Cited By ~ 36

Author(s):

K. BERRADA ◽

M. El BAZ ◽

H. ELEUCH ◽

Y. HASSOUNI

Keyword(s):

Comparative Study ◽

Coherent States ◽

Mixed States ◽

Qubit System ◽

Entanglement Measures ◽

Pure States ◽

Spin Coherent States

In this paper, we investigate two different entanglement measures, the negativity and concurrence, in the case of pure and mixed states of two-qubit system basing on the spin coherent states. For two-qubit pure states, the negativity is the same as the concurrence. For mixed states, using a simplified expression of concurrence in Wootters' measure of entanglement, we write the bounds of Verstraete et al.1as a function of some new parameters and we compare the both measures for a class of mixed states.

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Probing the relationship between quantum entanglement and non-locality for different states

Modern Physics Letters B ◽

10.1142/s0217984914501462 ◽

2014 ◽

Vol 28 (18) ◽

pp. 1450146

Author(s):

Wen-Chao Ma ◽

Jia-Dong Shi ◽

Shuai Xu ◽

Xue-Ke Song ◽

Liu Ye

Keyword(s):

Sudden Death ◽

Quantum Entanglement ◽

Qubit System ◽

Pure States ◽

Werner States ◽

The Relationship ◽

Non Locality

The relationship between quantum entanglement and non-locality is studied in a two-qubit system for pure states and Werner states. It is found that Werner states are more entangled than pure states if one compares the negativity for a given degree of non-locality. Furthermore, we also find that the entanglement produces sudden death for pure states but reaches to a fixed value for Werner states if the non-locality is not satisfied.

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ENTANGLEMENT MEASURE OF BIPARTITE SYSTEM STATES

International Journal of Geometric Methods in Modern Physics ◽

10.1142/s0219887810004713 ◽

2010 ◽

Vol 07 (06) ◽

pp. 1051-1064 ◽

Cited By ~ 1

Author(s):

K. BERRADA ◽

Y. HASSOUNI

Keyword(s):

Coherent States ◽

Linear Entropy ◽

Entanglement Measure ◽

Mixed States ◽

Maximal Entanglement ◽

Bipartite System ◽

Pure States ◽

System States ◽

Entangled Coherent States

Linear entropy as a measure of entanglement is applied to explain conditions for minimal and maximal entanglement of bipartite nonorthogonal pure states. We formulate this measure in terms of the amplitudes of coherent states in the case of entangled coherent states and calculate the conditions. We generalize this formalism to the case of bipartite mixed states and show that the entanglement measure is also a function of the probabilities.

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Qubit masking in multipartite qubit system

Modern Physics Letters A ◽

10.1142/s021773232150156x ◽

2021 ◽

pp. 2150156

Author(s):

Wei-Min Shang ◽

Fu-Lin Zhang ◽

Jie Zhou ◽

Hui-Xian Meng ◽

Jing-Ling Chen

Keyword(s):

Recent Work ◽

Quantum Entanglement ◽

Quantum Correlation ◽

Entangled States ◽

Qubit System ◽

Qubit States

The no-masking theories show that it is impossible to mask the set of all qubit states into the quantum correlation of bipartite qubit system or tripartite qubit system. In this paper, we give a new proof of the no-masking situation of the tripartite qubit system. Recent work has shown that there exists a universal masker which can mask an arbitrary set of qubit states in four-qubit systems perfectly by means of the maximum entangled states. Here we show that there exist more than one masking scheme even for the same multipartite qubit system. Basing on the maximum entangled states we give the deterministic masking scenario for N-qubit system. In practice, decoherence hinders us from obtaining the maximum entangled states. From this viewpoint, the masking scenario based on non-maximum entangled states becomes more universal. Furthermore, we provide an approximate quantum masking scenario and investigate the relation between approximate masking and quantum entanglement.

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ENTANGLEMENT OF TWO-QUBIT NONORTHOGONAL STATES

International Journal of Modern Physics B ◽

10.1142/s0217979209052169 ◽

2009 ◽

Vol 23 (08) ◽

pp. 2021-2027 ◽

Cited By ~ 10

Author(s):

K. BERRADA ◽

A. CHAFIK ◽

H. ELEUCH ◽

Y. HASSOUNI

Keyword(s):

Coherent States ◽

Pure States ◽

Spin Coherent States

We studied the entangled two-qubit nonorthogonal pure states through spin coherent states. Using the concurrence as a measure of entanglement we express it as a function of the amplitudes of those states and find conditions for maximal and minimal entanglement.

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Entanglement of formation and quantum discord in multipartite j-spin coherent states

International Journal of Modern Physics B ◽

10.1142/s0217979220502379 ◽

2020 ◽

Vol 34 (26) ◽

pp. 2050237

Author(s):

H. Baba ◽

W. Kaydi ◽

M. Daoud ◽

M. Mansour

Keyword(s):

Coherent States ◽

Quantum Discord ◽

Quantum Correlations ◽

Quantum Systems ◽

Spin Coherent State ◽

Entanglement Of Formation ◽

Multipartite System ◽

Single Formula ◽

Qubit States ◽

Spin Coherent States

We study the entanglement of formation and the quantum discord contained in even and odd multipartite [Formula: see text]-spin coherent states. The key element of this investigation is the fact that a single [Formula: see text]-spin coherent state is viewed as comprising [Formula: see text] qubit states. We compute the quantum correlations present in the n even and odd [Formula: see text]-spin coherent states by considering all possible bipartite splits of the multipartite system. We discuss the different bi-partition schemes of quantum systems and we examine in detail the conservation rules governing the distribution of quantum correlations between the different qubits of the multipartite system. Finally, we derive the explicit expressions of quantum correlations present in even and odd spin coherent states decomposed in four spin sub-systems. We also analyze the properties of monogamy and we show in particular that the entanglement of the formation and the quantum discord obey the relation of monogamy only for even multipartite [Formula: see text]-spin coherent states.

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Entanglement of spin coherent mixed states

International Journal of Quantum Information ◽

10.1142/s0219749916500040 ◽

2016 ◽

Vol 14 (01) ◽

pp. 1650004 ◽

Cited By ~ 1

Author(s):

Mostafa Mansour ◽

Yassine Hassouni

Keyword(s):

Coherent States ◽

General Type ◽

Mixed States ◽

Statistical Mixture ◽

Linearly Independent ◽

Spin Coherent States

In this paper, we quantify the amount of entanglement of bipartite mixed states represented by a statistical mixture of the more general type of two-qubit non-orthogonal states of the form: [Formula: see text], constructed by linearly independent spin coherent states. We use the concurrence as a measure of entanglement and we study its behavior in terms of the amplitudes of SU(2) coherent states.

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Local Information as an Essential Factor for Quantum Entanglement

Entropy ◽

10.3390/e23060728 ◽

2021 ◽

Vol 23 (6) ◽

pp. 728

Author(s):

Zhaofeng Su

Keyword(s):

Quantum Entanglement ◽

Quantum Information Processing ◽

Local Information ◽

Essential Factor ◽

Qubit System ◽

Local Vectors ◽

Correlation Parameters ◽

The One ◽

Local Parameters

Quantum entanglement is not only a fundamental concept in quantum mechanics but also a special resource for many important quantum information processing tasks. An intuitive way to understand quantum entanglement is to analyze its geometric parameters which include local parameters and correlation parameters. The correlation parameters have been extensively studied while the role of local parameters have not been drawn attention. In this paper, we investigate the question how local parameters of a two-qubit system affect quantum entanglement in both quantitative and qualitative perspective. Firstly, we find that the concurrence, a measure of quantum entanglement, of a general two-qubit state is bounded by the norms of local vectors and correlations matrix. Then, we derive a sufficient condition for a two-qubit being separable in perspective of local parameters. Finally, we find that different local parameters could make a state with fixed correlation matrix separable, entangled or even more qualitatively entangled than the one with vanished local parameters.

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