# Quantum discord for two-qubit CS states: Analytical solution

We found an universal local unitary orthogonal transformation which transforms any centrosymmetric CS density matrix ho {CS} into the X density matrix ho X: H\otimes H ho {CS}H\otimes H= ho X, where H is the Hadamard transformation. Because quantum discord is invariant under the local unitary transformations, this remarkable property allows to get the discord of general two-qubit CS states in the analytical form using the corresponding well-known formulas for the X states. Examples of systems with CS density matrices provided from the recent literature, including XXZ spin model with the Dzyaloshinsky-Moriya interaction, a gas of spin-carrying particles in closed nanopore, and a family of pseudopure states.

Author: M. A. Yurishchev

Source: https://archive.org/