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 gc(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.
@article{arxiv.1908.00590,
title = {An efficient, tunable, and robust source of narrow-band photon pairs at the $^{87}$Rb D1 line},
author = {Roberto Mottola and Gianni Buser and Chris Müller and Tim Kroh and Andreas Ahlrichs and Sven Ramelow and Oliver Benson and Philipp Treutlein and Janik Wolters},
journal= {arXiv preprint arXiv:1908.00590},
year = {2020}
}