Single photons are a fundamental element of most quantum optical technologies. The ideal single-photon source is an on-demand, deterministic, single-photon source delivering light pulses in a well-defined polarization and spatiotemporal mode, and containing exactly one photon. In addition, for many applications, there is a quantum advantage if the single photons are indistinguishable in all their degrees of freedom. Single-photon sources based on parametric down-conversion are currently used, and while excellent in many ways, scaling to large quantum optical systems remains challenging. In 2000, semiconductor quantum dots were shown to emit single photons, opening a path towards integrated single-photon sources. Here, we review the progress achieved in the past few years, and discuss remaining challenges. The latest quantum dot-based single-photon sources are edging closer to the ideal single-photon source, and have opened new possibilities for quantum technologies.

中文翻译：

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高性能半导体量子点单光子源

单光子是大多数量子光学技术的基本元素。理想的单光子源是按需确定性单光子源，该光子以明确定义的偏振和时空模式传输光脉冲，并且正好包含一个光子。另外，对于许多应用而言，如果单个光子的所有自由度都无法区分，则具有量子优势。当前使用基于参数下转换的单光子源，尽管在许多方面都非常出色，但缩放到大型量子光学系统仍然具有挑战性。在2000年，显示出半导体量子点发出单光子，从而打开了通向集成单光子源的道路。在这里，我们回顾了过去几年取得的进展，并讨论了仍然存在的挑战。