Quantum frequency down-conversion of single photons at 1552 nm from single InAs quantum dot

Ma Ben^{1, 2, 3}, Wei Si-Hang^{1, 2, 3}, Chen Ze-Sheng^{1, 2, 3}, Shang Xiang-Jun^{1, 2, 3}, Ni Hai-Qiao^{1, 2, 3}, Niu Zhi-Chuan^{1, 2, 3, †}

(color online) Conversion efficiency of the PPLN crystal under 140 μW cw excitation power for different pump powers.