Implementation Of Quantum Entanglement Restoration Via Environment-Assisted Weak Measurement

Quantum information science, mainly containing quantum computation and quantum communication, is an innovative subject combining quantum mechanics and classical information science. The birth of quantum information science provides a new space for the development of information science. As an indispensable physical resource, quantum entanglement has been widely applied in the field of quantum information. However, during the practical information transmission, processing, or storage, the inevitable interaction between qubit and noisy environment would lead to the quantum decoherence. So, how to protect the quantum entanglement effectively becomes a research focus. For now, many effective methods have been suggested, such as decoherence-free subspace, dynamic decoupling, quantum error correction, quantum Zeno effects and so on.In this thesis, entanglement restoration schemes are proposed for the maximally two-qubit entangled state via environment-assisted and weak measurement reversal. According to the transmission of qubits, the schemes could be divided into three categories:sending one qubit, two qubits, and sending two qubits but restoring a qubit. The high fidelity of quantum entanglement can be probabilistically obtained between two remote participants via the environment-assisted coupling with quan-tum states and the weak measurement reversal. And the maximally entangled state can be probabilistically obtained with the optimal value of weak measurement re-versal in this scheme. In some specific cases, the maximally entangled states could also be probabilistically obtained even without the weak measurement reversal. In addition, we propose the quantum telepotation between two remote participants can be realized with high fidelity using environment-assisted weak measurement.