Super quantum discord for a class of X-states with weak measurements

Eftekhari, H.; Faizi, E.

doi:10.1016/j.cjph.2016.05.007

Cited by 1 publication

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References 26 publications

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“…At present, the attempts are made to obtain analytical formulas for the super quantum discord of X states with nonzero Bloch vectors [49,50]. In this connection, one should note that the authors do not take into account a possibility of intermediate optimal angles for the weak measurements which are a generalization of ordinary projective ones.…”

Section: Results and Perspectivesmentioning

confidence: 99%

On the quantum discord of general X states

Yurischev

2015

Quantum Inf Process

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Quantum discord Q is a function of density matrix elements. The domain of such a function in the case of two-qubit system with X density matrix may consist of three subdomains at most: two ones where the quantum discord is expressed in closed analytical forms (Q_{\pi/2} and Q_0) and an intermediate subdomain for which, to extract the quantum discord Q_\theta, it is required to solve in general numerically a one-dimensional minimization problem to find the optimal measurement angle \theta\in(0,\pi/2). Hence the quantum discord is given by a piecewise-analytic-numerical formula Q=\min{Q_{\pi/2}, Q_\theta, Q_0}. Equations for determining the boundaries between these subdomains are obtained. The boundaries consist of bifurcation points. The Q_{\theta} subdomains are discovered in the generalized Horodecki states, in the dynamical phase flip channel model, in the anisotropic spin systems at thermal equilibrium, in the heteronuclear dimers in an external magnetic field. We found that transitions between Q_{\theta} subdomain and Q_{\pi/2} and Q_0 ones occur suddenly but continuously and smoothly, i.e., nonanalyticity is hidden and can be observed in higher derivatives of discord function.Comment: 23 pages, 12 figures. arXiv admin note: text overlap with arXiv:1404.573

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Section: Results and Perspectivesmentioning

confidence: 99%

On the quantum discord of general X states

Yurischev

2015

Quantum Inf Process

View full text Add to dashboard Cite

show abstract

Super quantum discord for a class of X-states with weak measurements

Cited by 1 publication

References 26 publications

On the quantum discord of general X states

On the quantum discord of general X states

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