Abstract

An efficient resource of entanglement in atom-photon-based quantum networks are polarization-entangled photon pairs generated by type-II spontaneous parametric down-conversion (SPDC). Compatibility in frequency and bandwidth between such photons and a single trapped ⁴⁰Ca⁺-ion was first shown in [1]. The best SPDC entanglement values so far have been achieved by single-pass conversion in Sagnac configuration [2]. On the other hand, the highest pair rates are reported in cavity-enhanced sources [3]. The latter, however, tend to suffer from reduced state purity due to increasing probability of generating double pairs, and thermal effects in the crystal.

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