Distributing Polarization-Entangled Photon Pairs with High Rate Over Long Distances through Standard Telecommunication Fiber
Lijiong Shen, Chang Hoong Chow, Justin Yu Xiang Peh, Xi Jie Yeo, Peng Kian Tan, Christian Kurtsiefer · Physical Review Applied · 2022
Distributing entanglement through standard telecommunication fiber is particularly important for quantum key distribution protocols with low vulnerability over metropolitan distances. However, entanglement distribution over long distance through optical fiber so far could only be accomplished with moderate photon pair rates. In this work, we present entanglement distribution over 50 km of standard telecommunication fiber with a pair rate of more than 10 000 ${\mathrm{s}}^{\ensuremath{-}1}$ using a bright nondegenerate photon pair source. Signal and idler wavelengths of this source are optimized for low dispersion in optical fiber and high efficiency for single-photon avalanche diode detectors, respectively. The resulting modest hardware requirement and high rate of detected entangled photon pairs could significantly enhance practical entanglement-based quantum key distribution in existing metropolitan fiber networks.