  In the paper, we investigated the influence of local and global interaction
on the efficiency of continuous-time quantum spatial search. To do so, we
analyzed numerically chimera graph, which is defined as 2D grid with each node
replaced by complete bipartite graph. Our investigation provides a numerical
evidence that with a large number of local interactions the quantum spatial
search is optimal, contrary to the case with limited number of such
interactions. The result suggests that relatively large number of local
interactions with the marked vertex is necessary for optimal search, which in
turn would imply that poorly connected vertices are hard to be found.
