Analytic expression of quantum correlations in qutrit Werner states undergoing local and nonlocal unitary operations

2014 ◽  
Vol 14 (2) ◽  
pp. 559-572 ◽  
Author(s):  
Guofeng Li ◽  
Yimin Liu ◽  
Haojie Tang ◽  
Xiaofeng Yin ◽  
Zhanjun Zhang
Keyword(s):  
Quantum Correlations ◽  
Analytic Expression ◽  
Werner States

scholarly journals Local available quantum correlations for Bell Diagonal states and Markovian decoherence

2018 ◽  
Vol 64 (6) ◽  
pp. 662
Author(s):  
Hermann L Albrecht Q ◽  
Douglas F. Mundarain ◽  
Mario I. Caicedo S.
Keyword(s):  
Sudden Death ◽  
Quantum Discord ◽  
Quantum Correlations ◽  
Entanglement Sudden Death ◽  
Dissipative Dynamics ◽  
Phase Damping ◽  
Werner States ◽  
Kraus Operators

Local available quantum correlations (LAQCs), as dened by Mundarain et al. [19], are analytically determined for Bell Diagonal states. Using the Kraus operators formalism [10], we analyze the dissipative dynamics of 2-qubit LAQCs under Markovian decoherence. This is done for Werner states under the depolarizing [20] and phase damping channels [21]. Since Werner states are among those that exhibit the so called entanglement sudden death [27], the results are compared with the ones obtained for Quantum Discord [22], as analyzed by Werlang et al. [24], as well as for entanglement, i.e. Concurrence[7]. The LAQCs quantier, as Quantum Discord does, only vanishes asymptotically.

scholarly journals An investigation of some quantum correlations of Dirac fields in noninertial frames

2019 ◽  
Vol 97 (1) ◽  
pp. 42-50
Author(s):  
Mohammad Bagher Arjmandi
Keyword(s):  
Single Mode ◽  
Quantum Correlations ◽  
Initial State ◽  
Dirac Fields ◽  
Acceleration Parameter ◽  
Entanglement Of Formation ◽  
Single Mode Approximation ◽  
Accelerated Observers ◽  
Werner States

In this paper, some concepts of quantum correlations, such as one-way quantum deficit, purity, and entanglement of formation are investigated between the modes of Dirac fields in noninertial frames. We consider two bipartite divisions of a tripartite system constructed by initial Werner states, which is shared between two relatively accelerated observers. The degradation of these quantum correlations is shown when the acceleration parameter increases. However, a nonzero amount of correlations survives even at infinite acceleration limit. Furthermore, we study the inevitable influence of mixedness factor of initial state on the quantum correlations behaviour. Finally, we review our calculation beyond single-mode approximation and point out some differences and similarities between the two regimes.

scholarly journals Geometric measures of discordlike quantum correlations based on Tsallis relative entropy

2019 ◽  
Vol 17 (04) ◽  
pp. 1950034
Author(s):  
Weijing Li
Keyword(s):  
Relative Entropy ◽  
Quantum Correlation ◽  
Quantum Correlations ◽  
Partial Coherence ◽  
Good Measure ◽  
Coherence Measure ◽  
Geometric Measure ◽  
Special Cases ◽  
Analytic Expression ◽  
Correlation Measures

A kind of new geometric measure of quantum correlations is formulated. The proposed formulation is in terms of the quantum Tsallis relative entropy and can naturally be viewed as a one-parameter extension quantum discordlike measure that satisfies all requirements of a good measure of quantum correlations. It is of an elegant analytic expression and contains several existing good quantum correlation measures as special cases. The partial coherence measure is also investigated.

scholarly journals Chemical bond and entanglement of electrons in the hydrogen molecule

2014 ◽  
Vol 12 (05) ◽  
pp. 1450028
Author(s):  
Nikos Iliopoulos ◽  
Andreas F. Terzis
Keyword(s):  
Linear Combination ◽  
Chemical Bond ◽  
Configuration Interaction ◽  
Ground State ◽  
Hydrogen Molecule ◽  
Molecular System ◽  
Quantum Correlations ◽  
Atomic Orbitals ◽  
Analytic Expression ◽  
Electronic Wavefunction

We theoretically investigate the quantum correlations (in terms of concurrence of indistinguishable electrons) in a prototype molecular system (hydrogen molecule). With the assistance of the standard approximations of the linear combination of atomic orbitals and the configuration interaction methods we describe the electronic wavefunction of the ground state of the H 2 molecule. Moreover, we managed to find a rather simple analytic expression for the concurrence (the most used measure of quantum entanglement) of the two electrons when the molecule is in its lowest energy. We have found that concurrence does not really show any relation to the construction of the chemical bond.

Analytic expressions of quantum correlations in qutrit Werner states

2013 ◽  
Vol 12 (7) ◽  
pp. 2355-2369 ◽  
Author(s):  
Biaoliang Ye ◽  
Yimin Liu ◽  
Jianlan Chen ◽  
Xiansong Liu ◽  
Zhanjun Zhang
Keyword(s):  
Quantum Correlations ◽  
Analytic Expressions ◽  
Werner States

Studying quantum correlations dynamics in the phase space for continuous-variable Werner states and Bell-diagonal states

2019 ◽  
Vol 16 (07) ◽  
pp. 1950109
Author(s):  
Fatima-Zahra Siyouri ◽  
Hicham Ait Mansour ◽  
Fadoua Elbarrichi
Keyword(s):  
Wigner Function ◽  
Quantum Discord ◽  
Open Quantum Systems ◽  
Quantum Correlations ◽  
Continuous Variable ◽  
Quantum Systems ◽  
Qubit System ◽  
Classical Correlations ◽  
Werner States ◽  
System F

We investigate the ability of Wigner function to reveal and measure general quantum correlations in two-qubit open system. For this purpose, we analyze comparatively their dynamics for two different states, continuous-variable Werner states (CWS) and Bell-diagonal states (BDS), independently interacting with dephasing reservoirs. Then, we explore the effects of decreasing the degree of non-Markovianity on their behavior. We show that the presence of both quantum entanglement and quantum discord allow to have a negative Wigner function, in contrast to the result obtained for the closed two-qubit system [F. Siyouri, M. El Baz and Y. Hassouni, The negativity of Wigner function as a measure of quantum correlations, Quantum Inf. Process. 15(10) (2016) 4237–4252]. In fact, we conclude that negativity of Wigner function can be used to capture and quantify the amount of general non-classical correlations in open quantum systems.

scholarly journals Analytic Expression of Quantum Discords in Werner States under LQCC

Entropy ◽  
2020 ◽  
Vol 22 (2) ◽  
pp. 147
Author(s):  
Chuanmei Xie ◽  
Zhanjun Zhang ◽  
Jianlan Chen ◽  
Xiaofeng Yin
Keyword(s):  
Quantum Discord ◽  
Special Kind ◽  
Classical Communication ◽  
Werner State ◽  
Quantum Operations ◽  
Local Quantum ◽  
Before And After ◽  
Projective Measures ◽  
Analytic Expression ◽  
Werner States

In this paper, quantum discords in a special kind of states, i.e., Werner states by local quantum operations and classical communication (LQCC) protocols (WLQCC states), are studied. Nineteen parameters to quantify the quantum discords are reduced to four parameters in terms of properties of Werner states and quantum discord. In the case of orthogonal projective measures, analytic expression of quantum discords in WLQCC states is analytically worked out. Some properties of the quantum discord in the WLQCC states are obtained, especially the variation relations between the quantum discords and the parameters characterizing the WLQCC states. By virtue of numerical computations, quantum discords in a Werner state before and after LQCC protocols are compared. It is found that quantum discord in any WLQCC state cannot exceed that in the original Werner state.

A note on quantum correlations in Werner states under two collective noises

2014 ◽  
Vol 13 (12) ◽  
pp. 2713-2718 ◽  
Author(s):  
Chuanmei Xie ◽  
Yimin Liu ◽  
Guofeng Li ◽  
Zhanjun Zhang
Keyword(s):  
Quantum Correlations ◽  
Werner States

Entanglement of formation of rotationally symmetric states

2008 ◽  
Vol 8 (3&4) ◽  
pp. 295-310
Author(s):  
K.K. Manne ◽  
C.M. Caves
Keyword(s):  
General Class ◽  
Bipartite State ◽  
Entanglement Of Formation ◽  
Rotationally Symmetric ◽  
Invariant States ◽  
Different Dimensions ◽  
Analytic Expression ◽  
Werner States ◽  
Symmetric States ◽  
Isotropic States

Computing the entanglement of formation of a bipartite state is generally difficult, but special symmetries of a state can simplify the problem. For instance, this allows one to determine the entanglement of formation of Werner states and isotropic states. We consider a slightly more general class of states, rotationally symmetric states, also known as SU(2)-invariant states. These states are invariant under global rotations of both subsystems, and one can examine entanglement in cases where the subsystems have different dimensions. We derive an analytic expression for the entanglement of formation of rotationally symmetric states of a spin-$j$ particle and a spin-${1\over2}$ particle. We also give expressions for the I-concurrence, I-tangle, and convex-roof-extended negativity.

Role of Wigner function in studying quantum correlations

2016 ◽  
Vol 30 (26) ◽  
pp. 1650187 ◽  
Author(s):  
F. Siyouri ◽  
M. El Baz ◽  
Y. Hassouni
Keyword(s):  
Wigner Function ◽  
Quantum Correlations ◽  
Squeezed States ◽  
Werner States

In this paper, we investigate the possibility to use the Wigner function to detect and quantify quantum correlations in general. We study these quantum correlations for two quasi-Werner states formed with two general bipartite superposed squeezed states. We find then that the Wigner function is not sensitive to all kinds of quantum correlations but it only witnesses entanglement.

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