Research On Multicast Transmission In Quantum Communication Networks

Quantum communication technology is the product of multidisciplinary intersection.Its security and high efficiency are unique advantages,and it has been widely concerned by scholars.At present,quantum communication is gradually moving from theory to practice,and is developing towards network and practical.Information sharing and transmission between multiple users in quantum communication networks is the key to making quantum communication networking.This paper mainly uses quantum secret sharing technology and quantum cloning mechanism to design multi-user information sharing scheme and multicast routing scheme in quantum network.This paper first studies the sharing of important information among multiple users in quantum networks,and proposes a multi-layer quantum secret sharing protocol based on GHZ state.The sender has important information carried by the quantum state and wants to distribute this information to multiple intermediate nodes in the network.In this protocol,important information is spread and shared layer by layer from the root node,where the number of intermediate nodes in each layer constitutes a geometric sequence with a specific common ratio,ensuring that the diffusion speed increases exponentially.By sharing the maximum entangled GHZ state,a generalized Bell-based measurement is performed,and a qubit information is assigned to many intermediate nodes,which together protects important information.Only all the intermediate nodes in the last layer work together,and important information can be recovered at the destination node specified by the root node.Compared with other protocols,this protocol uses less entangled particle states to achieve more multi-party sharing and ensure the secure transmission of information.This paper studies the quantum cloning mechanism,and discusses the fidelity relationship of two copies,three copies and four copies of the universal quantum cloning mechanism.The expression of the fidelity of the output state of the 1?1+1+1+1 asymmetric quantum cloning mechanism is derived by a relatively simple method,and its consistency with the universal symmetric quantum cloning machine is verified.Finally,on the basis of quantum cloning research,this paper studies the implementation of multicast communication in quantum networks,and proposes a multicast routing scheme based on fidelity metrics.The transmission mode of quantum information in the network is defined,one-to-one transmission mode and one-to-many lossy transmission based on quantum cloning mechanism.The quantum network model is established,in a specific quantum network connected graph,the source node randomly selects multicast group members,with the number of replicas and the maximum number of hops of the shortest path of the source node and all multicast group members as the limit conditions,the fidelity of the information obtained by all the multicast group members is the maximum,and the optimal multicast tree is constructed;The methods of solving the optimal fidelity based on symmetric mechanism and asymmetric mechanism are described respectively.The simulation is carried out by taking the symmetry mechanism as an example.The results show that the protocol can select the optimal path from the source node to the multicast group members for the randomly generated quantum network connected graph,and then realize the multicast communication in the quantum network.