Pointing Out the Obstacle of Quantification of Quantum Discord

Composite quantum systems can be in generic states characterised not only by entanglement but also by more general quantum correlations .The inter-relation between these two quantities ensures of non-locality is still not completely understood. Last few years people are concentrating in studying the different aspects of non-locality of quantum mechanics. Many correlation measures have been introduced and well studied. Quantum discord is one of such correlation measure that creates new challenges among the physicists and mathematicians. New quantification of quantum discord is one of the fascinating area .The analytic formula has been introduced only two qubit X states only. So in this paper we study for the investigation of the difficulties in finding the analytic expression of quantum discord in general two and higher dimension quantum systems.