Mixed-State Entanglement and Quantum Communication
Mixed-State Entanglement and Quantum Communication
复制标题
混合态纠缠与量子通信
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
R. Horodecki
中科院分区：
文献类型：
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作者：
M. Horodecki;P. Horodecki;R. Horodecki
量子纠缠是量子形式主义最显着的特征之一[26]。它可以表达如下：如果两个系统在过去相互作用，通常不可能将单个状态向量分配给两个子系统中的任何一个[257]。这就是有时所谓的不可分离性原则。纠缠态的一个常见例子是单线态[258]，
$$ psi _ - = frac{1} {{sqrt 2 }}（左| {01}
右
角度-左| {10}
右
角）。 $$
(5.1)
可以看出，它不能表示为描述子系统状态的各个向量的乘积。从历史上看，纠缠首先由爱因斯坦、波多尔斯基和罗森 (EPR) [24] 以及薛定谔 [5] 认识到。在他们的著名论文中，EPR 提出了一种对世界的描述（称为“局域实在论”），它将独立且客观的现实分配给复合系统中分离良好的子系统的物理属性。然后 EPR 将局域实在论标准应用于与纠缠态相关的预测，得出量子力学不完整的结论。 EPR 批评是许多关于自然的量子描述和经典描述之间的根本差异的讨论的根源。
Quantum entanglement is one of the most striking features of the quantum formalism [26]. It can be expressed as follows: If two systems interacted in the past it is, in general, not possible to assign a single state vector to either of the two subsystems [257]. This is what is sometimes called the principle of nonseparability. A common example of an entangled state is the singlet state [258],
$$ psi _ - = frac{1} {{sqrt 2 }}(left| {01}
ight
angle - left| {10}
ight
angle ). $$
(5.1)
One can see that it cannot be represented as a product of individual vectors describing states of subsystems. Historically, entanglement was first recognized by Einstein, Podolsky and Rosen (EPR) [24] and by Schrodinger [5]. In their famous paper, EPR suggested a description of the world (called “local realism”) which assigns an independent and objective reality to the physical properties of the well-separated subsystems of a compound system. Then EPR applied the criterion of local realism to predictions associated with an entangled state to conclude that quantum mechanics was incomplete. The EPR criticism was the source of many discussions concerning fundamental differences between the quantum and classical descriptions of nature.