Abstract
We discuss how to calculate genuine multipartite quantum and classical correlations in symmetric, spatially invariant, mixed $n$-qubit density matrices. We show that the existence of symmetries greatly reduces the amount of free parameters to be optimized in order to find the optimal measurement that minimizes the conditional entropy in the discord calculation. We apply this approach to the states exhibited dynamically during a thermodynamic protocol to extract maximum work. We also apply the symmetry criterion to a wide class of physically relevant cases of spatially homogeneous noise over multipartite entangled states. Exploiting symmetries we are able to calculate the nonlocal and genuine quantum features of these states and note some interesting properties.
Highlights
How quantum systems can be correlated is typically discussed within three categories: non-local, non-separable, or non-classical
In this work, motivated by these physically relevant examples, we address the question of quantitatively studying genuine correlations, global discord, and multipartite non-locality for spatially symmetric n-qubit states, where we achieve analytic expressions, and further note some interesting differences between the figures of merit under the action of noisy channels
In this work we have addressed the quantitative analysis of quantum correlations in some broadly applicable and physically relevant classes of states
Summary
How quantum systems can be correlated is typically discussed within three categories: non-local, non-separable (entangled), or non-classical (discordant). Quantum discord was originally defined as the difference between two quantum analogues of the classical mutual information [1,2] The interest around such a quantumness quantifier is justified considering the fact that there are examples in mixed-state quantum computation where it appears clear that entanglement in not the only meaningful indicator [4,5,6]. In this work, motivated by these physically relevant examples, we address the question of quantitatively studying genuine correlations, global discord, and multipartite non-locality for spatially symmetric n-qubit states, where we achieve analytic expressions, and further note some interesting differences between the figures of merit under the action of noisy channels. Some complementary analyses can be found in Refs. [38,39] where multipartite correlations are quantitatively explored
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