We present an efficient and robust source of photons at the 87Rb D1-line (795 nm) with a narrow bandwidth of δ = 226(1) MHz. The source is based on non-degenerate, cavity-enhanced spontaneous parametric down-conversion in a monolithic optical parametric oscillator far below threshold. The setup allows for efficient coupling to single mode fibers. A heralding efficiency of ηheralded = 45(5) % is achieved, and the uncorrected number of detected photon pairs is 3.8 × 103/(s mW). For pair generation rates up to 5 × 105/s, the source emits heralded single photons with a normalized, heralded, second-order correlation function g c(2)<0.01. The source is intrinsically stable due to the monolithic configuration. Frequency drifts are on the order of δ/20 per hour without active feedback on the emission frequency. We achieved fine-tuning of the source frequency within a range of >2 GHz by applying mechanical strain.

中文翻译：

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在87Rb D1线上的窄带光子对的高效，可调谐且强大的源。

我们提出了87Rb D1线（795 nm）处的有效且鲁棒的光子源，其窄带宽为δ= 226（1）MHz。源基于远低于阈值的单片光学参量振荡器中的非简并的，腔增强的自发参量下变频。该设置允许有效耦合到单模光纤。达到ηheralded= 45（5）％的预示效率，并且未校正的检测到的光子对数为3.8×103 /（s mW）。对于高达5×105 / s的成对生成速率，光源发射具有预定义的，预定义的二阶相关函数gc（2）<0.01的预声明的单光子。源由于单片构造而本质上稳定。频率漂移约为每小时δ/ 20，而没有对发射频率的有效反馈。