Karli Yusuf, Avila Arenas Iker, Schimpf Christian, Garcia Junior Ailton Jose, Manna Santanu, Kappe Florian, Schwarz René, Undeutsch Gabriel, Aigner Maximilian, Peter Melina, Covre da Silva Saimon F, Rastelli Armando, Weihs Gregor, Remesh Vikas
Institut für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria.
Cavendish Laboratory, JJ Thomson Avenue, University of Cambridge, Cambridge, UK.
npj Quantum Inf. 2025;11(1):139. doi: 10.1038/s41534-025-01083-0. Epub 2025 Aug 11.
High-purity multi-photon states are essential for photonic quantum computing. Among existing platforms, semiconductor quantum dots offer a promising route to scalable and deterministic multi-photon state generation. However, to fully realize their potential, we require a suitable optical excitation method. Current approaches to multi-photon generation rely on active polarization-switching elements (e.g., electro-optic modulators, EOMs) to spatio-temporally demultiplex single photons. Yet, the achievable multi-photon rate is fundamentally limited by the switching speed of the EOM. Here, we introduce a fully passive demultiplexing technique that leverages a stimulated two-photon excitation process to achieve switching rates only limited by the quantum dot lifetime. We demonstrate this method by generating two-photon states from a single quantum dot without requiring active switching elements. Our approach significantly reduces the cost of demultiplexing while shifting it to the excitation stage, enabling loss-free demultiplexing and effectively doubling the achievable multi-photon generation rate when combined with existing active demultiplexing techniques.
高纯度多光子态对于光子量子计算至关重要。在现有的平台中，半导体量子点为可扩展且确定性的多光子态生成提供了一条有前景的途径。然而，为了充分实现其潜力，我们需要一种合适的光学激发方法。当前生成多光子的方法依赖于有源偏振切换元件（例如，电光调制器，EOM）来对单光子进行时空解复用。然而，可实现的多光子速率从根本上受到EOM切换速度的限制。在此，我们引入一种完全无源的解复用技术，该技术利用受激双光子激发过程来实现仅受量子点寿命限制的切换速率。我们通过从单个量子点生成双光子态而无需有源切换元件来演示此方法。我们的方法显著降低了解复用成本，同时将其转移到激发阶段，实现了无损耗解复用，并且与现有的有源解复用技术相结合时有效地使可实现的多光子生成速率翻倍。
