  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.
