Development of a frequency-stabilized pump source at 436  nm for 606  nm–1.5  µm entangled photon pair generation

We developed a frequency-stable laser light source operating at 436 nm to produce entangled photon pairs at 606 nm and 1.5 µm via spontaneous parametric down conversion. This light source was produced via the sum frequency generation of two lasers operating at 852 and 895 nm, each stabilized to the D2 and D1 transitions of cesium atoms, respectively. We evaluated the frequency stability of the light source using heterodyne measurements between two identical setups. The developed light source can be used to generate frequency-stable photon pairs, a critical requirement for quantum repeaters using Pr:YSO quantum memories.