NMR dynamics of quantum discord for spin-carrying gas molecules in a closed nanopore
M. A. Yurishchev · Journal of Experimental and Theoretical Physics · 2014
A local orthogonal transformation that transforms any centrosymmetric density matrix of a two-qubit system to the X form has been found. A piecewise-analytic-numerical formula Q = min{Q π/2, Q θ, Q 0}, where Q π/2 and Q 0 are analytical expressions and the branch Q 0 θ can be obtained only by numerically searching for the optimal measurement angle θ ∈ (0, π/2), is proposed to calculate the quantum discord Q of a general X state. The developed approaches have been applied for a quantitative description of the recently predicted flickering (periodic disappearance and reappearance) of the quantum-information pair correlation between nuclear 1/2 spins of atoms or molecules of a gas (for example, 129Xe) in a bounded volume in the presence of a strong magnetic field.