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) Schematic of the combined experimental setup. (a) Confocal microscope for the investigation of the QD sample. (b) Frequency conversion setup. AL: aspheric lens, APD: avalanche photodiode, MMF: multimode fiber, LF: long pass filter, BS: beam splitter, SSPD: superconducting single-photon detector, WDM: wavelength division multiplex.