Quantum State Sharing With Asymmetric Entangled States As Quantum Channel

Quantum Information Science (QIS) is a new subject combined with Quantum Mechanics and Information Science, which has made a surprise progress both in theoretical and experimental field in the past two decades. It has created many miracles, such as absolute secure quantum key, quantum dense coding, quantum teleportation, especially quantum secret sharing which is proposed recently.Quantum secret sharing (QSS) is one of the most important directions in Quantum Information Science, QSS is a method protecting private information by splitting it into several shares. Each share-holder possesses one share, and the secret cannot be recovered unless the share-holders collaborate with each other. Quantum secret sharing is all important type of quantum cryptography protocol which utilizes quantum effects to realize secret sharing. The quantum physics law guarantees the security of protocol. Quantum secret sharing can protect not only classical information but also a quantum one, this is so called Quantum State Sharing (QSTS). We proposed some new quantum state sharing protocols and analyzed the security in detail in the dissertation.In this article, we proposed some schemes for quantum state shaing based on symmetric entangled state, and then we devote to study the quantum state sharing by using asymmetric entangled states as quantum channel, and the main contents are given as follows:1. We proposed schemes for quantum state sharing based on symmetric three-qubit and four-qubit entangled states as quantum channel. Explicit procotols for quantum state sharing of a single qubit and an arbitrary two-qubit entangled state are illustrated. We also consider the security against ceratin eavesdropping attacks. Moreover, a generalization of the scheme to multi-particle case is also outlined.2. Schemes for quantum state sharing by using asymmetric multiparticle entangled states were proposed. Explicit protocols for quantum state sharing of a single-qubit state and two-qubit entangled state via asymmetric three-particle entangled state are illustrated. The four-particle asymmetric entangled state is also used as quantum channel to split the unknown two-qubit entangled state. These protocols are also considered to be secure. In the last section, we prososed schemes for quantum state sharing of a single-qubit state via an arbitrary high-dimensional entangled state.