Analytical expressions of global quantum discord for two classes of multi-qubit states

Global quantum discord (GQD), proposed by Rulli and Sarandy [C.C. Rulli, M.S. Sarandy, Phys. Rev. A 84 (2011) 042109], is a generalization of quantum discord to multipartite states. In this Letter, we provide an equivalent expression for GQD, and obtain the analytical expressions of GQD for two classes of multi-qubit states. The phenomena of sudden transition and freeze of GQD are also discussed.

► We provide an equivalent expression for global quantum discord.
► We obtain the analytical expressions of global quantum discord for two classes of multi-qubit states.
► The phenomena of sudden transition and freeze of global quantum discord are discussed.