If a photon interacts with a member of an entangled photon pair via a so-called Bell-state measurement (BSM), its state is teleported over principally arbitrary distances onto the second member of the pair. Starting in 1997, this puzzling prediction of quantum mechanics has been demonstrated many times; however, with one very recent exception, only the photon that received the teleported state, if any, travelled far while the photons partaking in the BSM were always measured closely to where they were created. Here, using the Calgary fibre network, we report quantum teleportation from a telecommunication-wavelength photon, interacting with another telecommunication photon after both have travelled over several kilometres in bee-line, onto a photon at 795~nm wavelength. This improves the distance over which teleportation takes place from 818~m to 6.2~km. Our demonstration establishes an important requirement for quantum repeater-based communications and constitutes a milestone on the path to a global quantum Internet.
@article{arxiv.1605.08814,
title = {Quantum teleportation across a metropolitan fibre network},
author = {Raju Valivarthi and Marcel. li Grimau Puigibert and Qiang Zhou and Gabriel H. Aguilar and Varun B. Verma and Francesco Marsili and Matthew D. Shaw and Sae Woo Nam and Daniel Oblak and Wolfgang Tittel},
journal= {arXiv preprint arXiv:1605.08814},
year = {2016}
}