We experimentally demonstrate two-photon interference of a time-energy entangled superradiant photon pair generated via collective two-photon coherence in Doppler-broadened cascade-type 87Rb atoms. The two photons originally proposed by J. D. Franson are realized as a superradiant photon pair, which are generated from the cascade atomic system with a relatively long lifetime of the initial state and a considerably shorter lifetime of the intermediate state. The achievement of two-photon interference with photon-pair sources generated from inhomogeneous atomic ensembles constitutes an important result for time-energy entanglement based on atom-photon interaction.

中文翻译：

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通过集体两光子相干性从多普勒增宽的原子团中纠缠光子对

我们实验证明了通过多普勒扩展级联型87Rb原子中的集体双光子相干产生的时间能量纠缠的超辐射光子对的双光子干涉。JD Franson最初提出的两个光子被实现为超辐射光子对，它们是由级联原子系统生成的，其初始状态的寿命相对较长，而中间状态的寿命则相对较短。利用不均匀原子团簇产生的光子对源实现双光子干涉，是基于原子-光子相互作用的时间-能量纠缠的重要结果。