Hierarchical Quantum Communication Based On Multi-particle States

Quantum information science is a new field of intersectional produced by thecombination of Computer Science, Informatics and the Quantum Physics. It providesa new principle and method for the21st century the development of informationscience. With the rapid development of economy and science, Because of theeconomic, political and military etc, Espionage event occur frequently in recent years.As an important branch of quantum information science, Quantum communicationhas become one of the focuses of strategic competition in the world, which is gainingmore and more attention because of its characteristic of absolute safety in the processof communication.On the basis of previous theoretical research, this paper discusses two kinds ofbased on the multiple particle state to realize the controlled unknown two-qubitentangled state quantum communication scheme:(a) With seven particle state as the quantum channel, realized the controlledQuantum communication of an unknown two-qubit entangled state. In the scenario,the sender can set a number of the receiver and a controller. Controller does not havethe ability to receive the unknown state, he can only to control two particle unknownstate of the receiver recovered with the sender. Sender needs to perform four-qubitjoint von-Neumann measurement on her qubits, controller needs to do measurementunder the calculation base for him particles. Both of the measurement results are sentto the receiver, the receiver make a corresponding unitary transformation for theParticles that they have, it will be return to the two-qubit unknown state again.(b) With six particle state as quantum channel, realize the controlledhierarchical quantum communication of unknown two-qubit entangled state. In thescenario, the sender set a senior receiver, a low-level receiver and a controller withoutreceiving capability. Sender needs to perform three-qubit joint von-Neumannmeasurement on her qubits, according to the hierarchy of the receiver, the controller need to perform Separate measurement or jointly measurement for their own particles.Senior receivers can reconstruct the unknown state with the help of the receiver andcontroller, but the lower receiver requires Assist in all the three parties (the recipient,controllers, senior receiver etc), to reconstruct the unknown state of three parties.Above two kinds of schemes, the different receivers in the first solution have thesame ability to restore the unknown state. The second scheme different receivers torestore the abilities of the unknown state are different. The sender can accord thedifferent levels of trust in the receiver to choose the different quantum communicationscheme.