  Quantum discord witnesses the nonclassicality of quantum states even when
there is no entanglement in these quantum states. This type of quantum
correlation also has some interesting and significant applications in quantum
information processing. Quantum discord has been evaluated explicitly only for
certain class of two-qubit states. We extend the previous studies to $2 \otimes
d$ quantum systems and derive an analytical expression for quantum discord for
a two-parameter class of states for $d \geq 3$. We compare quantum discord,
classical correlation, and entanglement for qubit-qutrit systems to demonstrate
that different measures of quantum correlation are not identical and
conceptually different.
