Entangled photon transmission from a quantum dot over loop-back fiber in Cambridge network

Quantum dots are considered to be one of the most important quantum emitters due to their ability of emitting entangled single photons, which have not yet been practically used for large-scale quantum communication. In this work [1], we have realized the transmission of polarization-encoded entangled single photons at the telecommunication O-band emitted from a quantum dot over a loop-back fiber in the Cambridge fiber network. To maintain the polarization, an active feedback system with two classical reference beams is implemented. Stable transmission of high-fidelity (91.3%) entanglement has been achieved over one week, which is a significant step toward the application of quantum dots in quantum networks.