Preparation And Application Of Quantum Entangled States

Quantum entanglement is the core resource of quantum information technology and plays a very important role in quantum communication.Quantum entanglement is applied in many frontier fields,such as quantum teleportation,quantum key distribution,quantum security direct communication,and other fields.Therefore,the preparation of quantum entangled states is a fundamental problem in the field of quantum information.There are many types of entanglement.In a two-particle system,there is one type of entanglement,i.e.the Bell state.In a three-particle system,there are two types of entanglement,i.e.the Greenberger–Horne–Zeilinger(GHZ)state and the W state.However,there are many types of multi-particle entanglement,such as the multi-particle GHZ state,the multi-particle W state,the Dicke state,the cluster state,and so on.Besides the entanglement described above,there is another type of entanglement—logic-qubit entanglement.A logic qubit encodes multiple physical qubits,and has been widely discussed in quantum computation for error correction.The concatenated Greenberger-Horne-Zeilinger(c-GHZ)state is a new type of logic-qubit entanglement,which shows its potential application in both large-scale quantum networks and fault-tolerant quantum computation.So the research on the preparation of c-GHZ state is very important.The main work of this paper is to propose a scheme of entanglement preparation based on the non-linear Kerr(cross-kerr)medium c-GHZ state.We first prepared from the simplest form of c-GHZ state,and then generalized the scheme to the preparation of c-GHZ state of any number of particles.Moreover,the probability of success of our scheme can theoretically reach 100%.In addition,we also proposed based on super bell state tripartite entanglement of quantum secure direct communication scheme,on the basis of the original bell state increased the polarization and path two degrees of freedom,to separate coding.The scheme not only enlarges the channel capacity,but also realizes the tripartite information security sharing,and the information that one party sends to the other two parties can be independent and different.