Quantum Secret Sharing Scheme

Quantum cryptography is the outcome of the combination of quantum theory with the cryptography, and becomes one of the most rewarded research fields in quantum secure communication to follow with interest and to do research. While, the quantum secret sharing (QSS) is one of the key research areas of the quantum cryptography, in which the quantum information is divided into several parts, and any one of the receivers can not obtain the whole information alone, only after cooperation with all other receivers can the whole information be recovered. In addition, any eavesdropping and cheating by one of the receivers can be detected by the sender. It provides a new way of thinking and a new method for managing the key safely for the quantum secret communication.The thesis mainly contributes to the study of the protocols of quantum secret sharing. Two protocols for sending a message in the form of a sequence of classical bits and for sending a quantum state are proposed, respectively. In the first protocol, a reusable W state is used to sending a classical message, in which the entangled W state of three particles is used as carrier. All operations in this protocol are local and the probabilities of interception and cheating by one of the receivers are very small. The other protocol is to use the entangled W state of three particles as a channel to complete the teleportation of two-qubit and also by the same channel to feedback receiving information realizing a new teleportation of two-qubit.The thesis is organized as follows:in the first chapter titled with introduction, the research status both in the county and from abroad are introduced. The quantum information theory including quantum bit, quantum no-clone theorem, quantum entanglement and swapping, quantum measurement etc is presented as basic theory in chapter two. In the third chapter, quantum secret sharing is elaborated, including the introduction of the differences between classical secret sharing and quantum secret sharing, as well as quantum teleportation. In the fourth chapter, new research results are set forth, that is our two protocols for the quantum secret sharing. A summary and a prospect for the future are given in the final chapter.