We demonstrate a low-noise frequency down-conversion of photons at 637 nm to the telecommunication band at 1587 nm by the difference frequency generation in a periodically-poled lithium niobate. An internal conversion efficiency of the converter is estimated to be 0.44 at the maximum which is achieved by a pump power of 430 mW, whereas a rate of internal background photons caused by the strong cw pump laser is estimated to be 9 kHz/mW within a bandwidth of about 1 nm. By using the experimental values related to the intrinsic property of the converter, and using the intensity correlation and the average photon number of a 637-nm input light pulse, we derive the intensity correlation of a converted telecom light pulse. Then we discuss feasibility of a single-photon frequency conversion to the telecommunication band for a long-distance quantum communication based on NV centers in diamond.
@article{arxiv.1402.2944,
title = {A low-noise frequency down-conversion to the telecommunication band for a quantum communication based on NV centers in diamond},
author = {Rikizo Ikuta and Toshiki Kobayashi and Shuto Yasui and Shigehito Miki and Taro Yamashita and Hirotaka Terai and Mikio Fujiwara and Takashi Yamamoto and Masato Koashi and Masahide Sasaki and Zhen Wang and Nobuyuki Imoto},
journal= {arXiv preprint arXiv:1402.2944},
year = {2017}
}