Zhang Yingwen, Agnew Megan, Roger Thomas, Roux Filippus S, Konrad Thomas, Faccio Daniele, Leach Jonathan, Forbes Andrew
CSIR National Laser Centre, PO Box 395, Pretoria, 0001, South Africa.
Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario, K1N 6N5, Canada.
Nat Commun. 2017 Sep 21;8(1):632. doi: 10.1038/s41467-017-00706-1.
High-bit-rate long-distance quantum communication is a proposed technology for future communication networks and relies on high-dimensional quantum entanglement as a core resource. While it is known that spatial modes of light provide an avenue for high-dimensional entanglement, the ability to transport such quantum states robustly over long distances remains challenging. To overcome this, entanglement swapping may be used to generate remote quantum correlations between particles that have not interacted; this is the core ingredient of a quantum repeater, akin to repeaters in optical fibre networks. Here we demonstrate entanglement swapping of multiple orbital angular momentum states of light. Our approach does not distinguish between different anti-symmetric states, and thus entanglement swapping occurs for several thousand pairs of spatial light modes simultaneously. This work represents the first step towards a quantum network for high-dimensional entangled states and provides a test bed for fundamental tests of quantum science.Entanglement swapping in high dimensions requires large numbers of entangled photons and consequently suffers from low photon flux. Here the authors demonstrate entanglement swapping of multiple spatial modes of light simultaneously, without the need for increasing the photon numbers with dimension.
高比特率长距离量子通信是一种针对未来通信网络提出的技术，它依赖于高维量子纠缠作为核心资源。虽然已知光的空间模式为高维纠缠提供了一条途径，但要在长距离上稳健地传输这种量子态仍然具有挑战性。为了克服这一问题，纠缠交换可用于在未相互作用的粒子之间生成远程量子关联；这是量子中继器的核心要素，类似于光纤网络中的中继器。在此，我们展示了光的多个轨道角动量态的纠缠交换。我们的方法不区分不同的反对称态，因此纠缠交换同时发生在数千对空间光模式之间。这项工作代表了迈向高维纠缠态量子网络的第一步，并为量子科学的基础测试提供了一个试验平台。高维纠缠交换需要大量的纠缠光子，因此存在光子通量低的问题。本文作者展示了同时对光的多个空间模式进行纠缠交换，而无需随着维度增加光子数量。
