  The study of quantum correlations in High-dimensional bipartite systems is
crucial for the development of quantum computing. We propose relative entropy
as a distance measure of correlations may be measured by means of the distance
from the quantum state to the closest classical-classical state. In particular,
We establish relations between relative entropy and quantum discord quantifiers
obtained by means of orthogonal projective measurements. We show that for
symmetrical X-states density matrices the quantum discord is equal to relative
entropy. At the end of paper, various examples of X-states such as two-qubit
and qubit-qutrit have been demonstrated .
