Detecting two qubit both-way positive discord states

International audienceQuantum discord plays a pragmatic role in analyzing nonclassical featureof quantum correlations beyond entanglement. It is used in severalinformation processing protocols which lacks sufficient amount ofentanglement to be used as a resource. We have provided with ananalytical method of detecting quantum discord of an arbitrary two qubitstate. We have formulated a set of necessary and sufficient conditionsfor any two qubit state to be a both-way non-zero quantum discord state.As quantum discord is asymmetric in nature, we have framed the set of ifand only if conditions for a two qubit state to be classical-quantum aswell for it to be quantum-classical. Interestingly, not only correlationtensor but also local Bloch vector (corresponding to the classicalparty) plays a role for detecting the state to be a positive discordstate