  In this article, we introduce the Sharma-Mittal entropy of a graph, which is
a generalization of the existing idea of the von-Neumann entropy. The
well-known R{\'e}nyi, Thallis, and von-Neumann entropies can be expressed as
limiting cases of Sharma-Mittal entropy. We have explicitly calculated them for
cycle, path, and complete graphs. Also, we have proposed a number of bounds for
these entropies. In addition, we have also discussed the entropy of product
graphs, such as Cartesian, Kronecker, Lexicographic, Strong, and Corona
products. The change in entropy can also be utilized in the analysis of growing
network models (Corona graphs), useful in generating complex networks.
