We study the existence of quantum state transfer in $\mathcal{Q}$ -graphs in this paper. The $\mathcal{Q}$ -graph of a graph $G$ , denoted by $\mathcal{Q}(G)$ , is the graph derived from $G$ by plugging a new vertex to each edge of $G$ and joining two new vertices which lie on adjacent edges of $G$ by an edge. We show that, if all eigenvalues of a regular graph $G$ are integers, then its $\mathcal{Q}$ -graph $\mathcal{Q}(G)$ has no perfect state transfer. In contrast, we also prove that the $\mathcal{Q}$ -graph of a regular graph has pretty good state transfer under some mild conditions. Finally, applying the obtained results, we also exhibit many new families of $\mathcal{Q}$ -graphs having no perfect state transfer, but admitting pretty good state transfer.We study the existence of quantum state transfer in $\mathcal{Q}$-graphs in this paper. The $\mathcal{Q}$-graph of a graph $G$, denoted by $\mathcal{Q}(G)$, is the graph derived from $G$ by plugging a new vertex to each edge of $G$ and joining two new vertices which lie on adjacent edges of $G$ by an edge. We show that, if all eigenvalues of a regular graph $G$ are integers, then its $\mathcal{Q}$-graph $\mathcal{Q}(G)$ has no perfect state transfer. In contrast, we also prove that the $\mathcal{Q}$-graph of a regular graph has pretty good state transfer under some mild conditions. Finally, applying the obtained results, we also exhibit many new families of $\mathcal{Q}$-graphs having no perfect state transfer, but admitting pretty good state transfer.

arXiv:2108.07590Aug 17, 20210 citations

We study the existence of quantum state transfer in

\mathcal{Q}

-graphs in this paper. The

\mathcal{Q}

-graph of a graph

G

, denoted by

\mathcal{Q}(G)

, is the graph derived from

G

by plugging a new vertex to each edge of

G

and joining two new vertices which lie on adjacent edges of

G

by an edge. We show that, if all eigenvalues of a regular graph

G

are integers, then its

\mathcal{Q}

-graph

\mathcal{Q}(G)

has no perfect state transfer. In contrast, we also prove that the

\mathcal{Q}

-graph of a regular graph has pretty good state transfer under some mild conditions. Finally, applying the obtained results, we also exhibit many new families of

\mathcal{Q}

-graphs having no perfect state transfer, but admitting pretty good state transfer.