Entanglement of the orbital angular momentum states of photons
Entanglement of the orbital angular momentum states of photons
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DOI：
10.1038/35085529
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发表时间：
2001-07-19
期刊：
影响因子：
64.8
通讯作者：
Zeilinger, A
中科院分区：
文献类型：
--
作者：
Mair, A;Vaziri, A;Zeilinger, A
纠缠量子态是不可分离的，无论其组成部分的空间分离如何。这是量子力学中一种被称为量子非局部性的表现（1,2）。由此得出的一个重要结论是，对两粒子纠缠态中一个粒子的状态的测量可以立即定义第二个粒子的状态，而在测量之前，两个粒子都没有自己明确的状态。迄今为止，纠缠的实验实现仅限于双态量子系统（3-6），例如，涉及光子的两个正交偏振态。在这里，我们证明了涉及携带轨道角动量的电磁场的空间模式的纠缠。由于这些模式可以用来定义一个无限维的离散希尔伯特空间，这种方法提供了一种涉及许多正交量子态的纠缠的实用途径，而不仅仅是两个多维纠缠态在量子信息领域可能相当重要（7,8），例如，在量子密码学中更有效地利用通信信道（9-11）。
Entangled quantum states are not separable, regardless of the spatial separation of their components. This is a manifestation of an aspect of quantum mechanics known as quantum nonlocality(1,2). An important consequence of this is that the measurement of the state of one particle in a two-particle entangled state defines the state of the second particle instantaneously, whereas neither particle possesses its own well-defined state before the measurement. Experimental realizations of entanglement have hitherto been restricted to two-state quantum systems(3-6), involving, for example, the two orthogonal polarization states of photons. Here we demonstrate entanglement involving the spatial modes of the electromagnetic field carrying orbital angular momentum. As these modes can be used to define an infinitely dimensional discrete Hilbert space, this approach provides a practical route to entanglement that involves many orthogonal quantum states, rather than just two Multi-dimensional entangled states could be of considerable importance in the field of quantum information(7,8), enabling, for example, more efficient use of communication channels in quantum cryptography(9-11).