Preparation And Application Of Quantum Entangled States

Quantum information science is brand-new interdisciplinary science subject rapidly developed recent years, it is the combination of quantum mechanics and information science. What is called quantum information science is substantively to research information science encoding with quantum states. Quantum state having nonclassical quantum entanglement phenomenon, quantum information can achive many new functions surpassing classical information, such as quantum key distribution based on entanglement, quantum teleportation, dense encoding and so on. Entanglement is a kind of useful information resource,and it could be said that in a large part, the purpose of quantum information researching is to exploit and apply quantum entanglement, so it makes sense to research quantum entanglement.This article has several parts as follows:1. First, beginning with the argument about quantum fundamental theory, quantum entanglement is put forward; then proving the Bell theorem,consequently giving a method to validate local hid-variable theorem in experiment; finally, giving the definition of entanglement, introducing several kinds of entangled states and discussing the problem of measuring entanglement.2. Introducing several classical applied scheme of entanglement: dense encoding, quantum teleportation and quantum key distribution. Summarizing researching development about entanglement in a few new fields and some of them allow entanglement to get rid of fundamental researching; field to practicality.3. Introducing several schemes of preparing entangled states: ion trap scheme, cavity quantum electrodynamics scheme and spontaneous parametric down conversion(SPDC), analysing the advantages and disadvantages of each scheme combining with their characteristics and introducing the recently new development about SPDC.4. Designing a efficient quantum key distribution scheme based on partial entangled photons source, introducing the optical component in the scheme, analysing the feasibility, security, bit error rate and efficiency of the scheme, comparing it with congenetic scheme in a group of selected parameters. It can be seen that our scheme is safer, more efficient,simplier and easier to operate.