Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstrasse 20, 01069, Dresden, Germany.
Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstrasse 2, 30167, Hannover, Germany.
Nat Commun. 2018 Jul 31;9(1):2994. doi: 10.1038/s41467-018-05456-2.
Many quantum photonic technologies require the efficient generation of entangled pairs of photons, but to date there have been few ways to produce them reliably. Sources based on parametric down conversion operate at very low efficiency per pulse due to the probabilistic generation process. Semiconductor quantum dots can emit single pairs of entangled photons deterministically but they fall short due to the extremely low-extraction efficiency. Strategies for extracting single photons from quantum dots, such as embedding them in narrowband optical cavities, are difficult to translate to entangled photons. Here, we build a broadband optical antenna with an extraction efficiency of 65% ± 4% and demonstrate a highly-efficient entangled-photon source by collecting strongly entangled photons (fidelity of 0.9) at a pair efficiency of 0.372 ± 0.002 per pulse. The high brightness achieved by our source represents a step forward in the development of optical quantum technologies.
许多量子光子技术都需要高效地产生纠缠光子对，但迄今为止，可靠产生它们的方法寥寥无几。由于概率生成过程，基于参量下转换的源在每个脉冲的效率非常低。半导体量子点可以确定性地发射单对纠缠光子，但由于极低的提取效率而有所欠缺。从量子点中提取单光子的策略，例如将它们嵌入窄带光学腔中，很难转化为纠缠光子。在这里，我们构建了一个宽带光天线，提取效率为 65%±4%，并通过收集强纠缠光子（保真度为 0.9）实现了高效的纠缠光子源，每个脉冲的对效率为 0.372±0.002。我们的光源实现的高亮度代表着光学量子技术发展的一个进步。
