The development of quantum relays for long haul and attack-proof quantum communication networks operating with weak coherent laser pulses requires entangled photon sources at telecommunication wavelengths with intrinsic single-photon emission for most practical implementations. Using a semiconductor quantum dot emitting entangled photon pairs in the telecom O-band, we demonstrate for the first time a quantum relay fulfilling both of these conditions. The system achieves a maximum fidelity of 94.5 % for implementation of a standard 4-state protocol with input states generated by a laser. We further investigate robustness against frequency detuning of the narrow-band input and perform process tomography of the teleporter, revealing operation for arbitrary pure input states, with an average gate fidelity of 83.6 %. The results highlight the potential of semiconductor light sources for compact and robust quantum relay technology, compatible with existing communication infrastructures.
@article{arxiv.1704.07765,
title = {Quantum-dot based telecom-wavelength quantum relay},
author = {J. Huwer and M. Felle and R. M. Stevenson and J. Skiba-Szymanska and M. B. Ward and I. Farrer and R. V. Penty and D. A. Ritchie and A. J. Shields},
journal= {arXiv preprint arXiv:1704.07765},
year = {2017}
}