中文摘要：

高保真的量子纠缠是量子信息科学中最重要的物理资源之一，特别是在量子通信中。然而，在实际的传输和存储过程中，纠缠的量子系统将不可避免地遭受信道噪声和环境的影响，导致纠缠的量子系统出现退相干。纠缠纯化和纠缠浓缩就是两个用来克服退相干问题的量子技术，纠缠纯化是从混合纠缠态中提取高保真最大纠缠态的过程，而纠缠浓缩是从非最大纠缠纯态中提取最大纠缠态的过程。本文重点介绍一些重要的纠缠纯化和纠缠浓缩方案，以及他们的物理原理。

英文摘要：

High-fidelity quantum entanglement is one of the most important physical resources in quantum information science, especially in quantum communications. However, in a practical transmission or the process for storing an entangled quantum system, it inevitably suffers from channel noise and its environment. The noise will make the entangled quantum system decoherent. Entan- glement purification and entanglement concentration are two important quantum techniques for depressing the decoherence of the entanglement. Entanglement purification is used to extract some high-fidelity maximally entangled states from an ensemble in a mixed state, where entan- glement concentration is used to distill some maximally entangled states from an ensemble in a less-entangled pure state. This article focuses on the introduction of some important entanglement purification schemes and entanglement concentration schemes, as well as the physical principles of these schemes.