Future quantum networks will need flying qubits and stationary nodes. As for the generation of single photons which may act as flying qubits, resonantly excited single-semiconductor quantum dots are ideal in terms of their on-demand single-photon emission, indistinguishability, and brightness. Atomic systems can effectively act as mediators for photon–photon interactions, storage media, or building blocks for stationary qubits. Here, we hybridize these two systems and investigate the non-classical interference of spectral Lorentzian-shaped photons, fine-tuned between the cesium $(\mathrm{Cs})\text{-}{\mathrm{D}}_1$ hyperfine resonances. The temporal delay in the dispersive hot atomic cesium vapor amounts up to 50 times the photons’ initial width and reveals beats on the single quanta. The photons’ indistinguishability is preserved even after atomic-enabled delay. This proves that the interaction with the Cs vapor conserves the photons’ coherence. The role of spectral diffusion in the solid-state emitter is studied in single- and two-photon experiments in light of the strong frequency dependence of the atomic medium. Our results pave the way for efficient hybrid interfaces between quantum dots and hot atomic vapors as storage media in future quantum networks.

中文翻译：

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原子-量子点混合系统中的双光子干涉

未来的量子网络将需要飞行的量子比特和静止的节点。至于可能充当飞行量子位的单光子的产生，就其按需单光子发射，不可分辨性和亮度而言，共振激发的单半导体量子点是理想的。原子系统可以有效地充当光子与光子相互作用的媒介，存储介质或固定量子位的构建块。在这里，我们将这两个系统进行杂交，并研究在铯之间微调的光谱洛伦兹形光子的非经典干涉$（\mathrm{CS}）\text{--}{\mathrm{d}}_{\mathrm{1个}}$超精细共振。分散的热原子铯蒸气中的时间延迟高达光子初始宽度的50倍，并揭示了单个量子上的节拍。即使在启用原子的延迟之后，光子的不可区分性也得以保留。这证明与Cs蒸气的相互作用保留了光子的相干性。鉴于原子介质对频率的强烈依赖性，在单光子和双光子实验中研究了光谱扩散在固态发射器中的作用。我们的研究结果为量子点和热原子蒸气之间有效的混合界面铺平了道路，这些界面是未来量子网络中的存储介质。