Production, Evolution And Nonlocal Manipulation Of Quantum Entanglement

Quantum entanglement, due to its " spooky " nonlocality, has become a research hotspot in quantum mechanics since its birthday. Especially, in the last ten years, the development of quantum information science inspires peoples research interest in quantum entanglement. In its framework, quantum entanglement is viewed as a resource in quantum information processing, it is believed to be the main ingredient of quantum computer. Moreover, several quantum protocols, such as teleportation, dense coding, quantum cryptography, remote-state preparation and distributed quantum computation,quantum entanglement is the essential ingredient. In this thesis, we concretely study entanglement distribution via noisy quantum channels entanglement dark states in eharge-quantum-dots systems and the production of distant entanglement in spin-quantum-dot systems and its applications, symmetric telecloning and entanglement distribution of spin quantum states in spin chain.Chapter 1 is the exordium. We introduce the main concept and measure of entanglement, the main research results of entanglement and its applicationsIn Chapter 2, we firstly introduce the superoperator theory of quantum noisy channels, including the amplitude-damping channel, the phase-damping channel and the depolarizing channels. We distribute entanglement via the three typical kinds of noisy quantum channels with two modes:one-qubit transmission and two-qubit transmission. Lastly, we report the change of entanglement.In Chapter 3, we study the formation of dark states and the Aharonvo-Bohm effect in multi-quantum-dot systems. We firstly introduce the basic content of charge qubit, then investigate the formation of dark states and the Aharonvo-Bohm effect in coupled three- and four-quantum-dot systems.In Chapter 4, we firstly introduce the concept of spin quantum dot, then we propose a scheme to engineer a non-local two-qubit logic gate between two remote quantum-dot spins based on the idea of giant Faraday rotation and discuss the adaptability of our scheme. Lastly, we report our scheme' application to quantum information processing:the creation of distributed cluster states and quantum information transfer.In Chapter 5, we propose a physical realization of symmetric telecloning and entanglement distribution in spin chain. At the same time, we study the quantum discord in a two-spin-1/2 XXZ model in thermal equilibrium at temperature T in the presence of an external magnetic field B.Chapter is the last charter which is a summary of the work and an outlook of the thesis.