Telecom C-band single photons exhibit the lowest attenuation in optical fibers, enabling long-haul, quantum-secured communication. However, efficient coupling with optical fibers is crucial for these single photons to be effective carriers in long-distance transmission. We demonstrate an efficient fiber-coupled single photon source in the telecom C-band using InAs/InP quantum dots coupled to a tapered nanobeam. The tapered nanobeam structure facilitates directional emission that is mode-matched to a lensed fiber, resulting in a collection efficiency of up to 65% from the nanobeam to the single-mode fiber. Using this approach, we demonstrate single photon count rates of 575 ± 5 Kcps and a single photon purity of g⁽²⁾ (0) = 0.015 ± 0.003. Additionally, we demonstrate Hong–Ou–Mandel interference from the emitted photons with a visibility of 0.84 ± 0.06. From these measurements, we determine a photon coherence time of 450 ± 20 ps, a factor of only 8.3 away from the lifetime limit. This work represents an important step toward the development of telecom C-band single-photon sources emitting bright, pure, and indistinguishable photons, which are necessary to realize fiber-based long-distance quantum networks.

中文翻译：

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使用锥形纳米束波导实现高效、难以区分的电信 C 波段光子


电信 C 波段单光子在光纤中表现出最低的衰减，可实现长距离、量子安全通信。然而，与光纤的有效耦合对于这些单光子成为长距离传输的有效载体至关重要。我们使用与锥形纳米束耦合的 InAs/InP 量子点展示了电信 C 波段中的高效光纤耦合单光子源。锥形纳米束结构有利于与透镜光纤模式匹配的定向发射，从而使从纳米束到单模光纤的收集效率高达 65%。使用这种方法，我们证明了单光子计数率为 575 ± 5 Kcps，单光子纯度为 g ⁽²⁾ (0) = 0.015 ± 0.003。此外，我们还证明了发射光子的红欧曼德尔干涉，可见度为 0.84 ± 0.06。根据这些测量结果，我们确定光子相干时间为 450 ± 20 ps，与寿命极限仅相差 8.3 倍。这项工作代表了朝着开发可发射明亮、纯净且难以区分的光子的电信 C 波段单光子源迈出的重要一步，这对于实现基于光纤的长距离量子网络是必要的。