Hierarchical quantum information splitting with eight-qubit cluster states

In the paper, a scheme is proposed for hierarchical quantum information splitting with an unknown eight-qubit cluster state. The Boss Alice wants to distribute a quantum secret to seven distant agents who are divided into two grades. Three agents are in the upper grade and four agents are in the lower grade. Every agent of the upper grade only needs the collaboration of three of the other six agents to get the secret, but all the agents of the lower grade need the collaboration of all the other six agents. In other words, different agents in different grades have different authorities to recover Boss' secret. And the agent in upper grade is more powerful than the one in the lower grades which needs more information to recover the secret.