The Application Of Multiparticle Entanglement In Quantum Information

As one of the most striking features of quantum formalism, quantum entanglement is used in the field of quantum information as an effective resource. The bipartite entanglement has involved many interesting applications without classical counterpart, such as quantum teleportation, quantum dense coding, entanglement-based cryptography. The higher-dimension or multiparticle entangled states have more complex structure of entanglement and more fascinating properties, and will make some peculiar effects in processing quantum information. A larger part of quantum information theory is the qualitative and quantitative study of multiparticle entanglement. In this thesis, we focus our research on applying the multiparticle entanglement in quantum information processing, assisted by local operation and classical communication. The main results of this thesis are as follows:1. We studied a multi-output programmable quantum processor. Similar to a classical processor, a programmable quantum processor consists of a fixed quantum gate array, a quantum system as data register and a quantum system as program register. According to the order stored in the program register, the processor operates the quantum state in the data register. Based on the multiparticle entanglement, we devised a new quantum processor, which generates multiple outputs for an order and a data in one-shot operation. So the repeated operations on the quantum processor are avoided. We discussed the limitation of the multi-output programmable processor aroused by the elementary rules of quantum formalism.2. We considered the issue of using the multiparticle entanglement into remote preparation of quantum states. It needs infinite classical information to describe an unknown quantum state. But when sharing a pair of maximally entangled qubits, the controller can send only one bit classical information to prepare a quantum state, which is secretly chosen by the controller from a constrained set of quantum states, in the distant lab of the receiver. We generalized the remote preparation of quantum state to one receiver to multiple receivers, and discussed the relation between the quality of the output and the amount of entanglement consumed.3. It has been proved that the disentanglement can be realized by cloning locally subsystems of an entangled system. We found that if the cloner is asymmetric, not only the output of disentanglement can be obtained, but also the original entangled state can be nearly retained. When it is an asymmetric telecloning...