Teleportation is a fundamental concept of quantum mechanics with an important application in extending the range of quantum communication channels via quantum relay nodes. To be compatible with real-world technology such as secure quantum key distribution over fibre networks, such a relay node must operate at GHz clock rates and accept time-bin encoded qubits in the low-loss telecom band around 1550 nm. Here, we show that InAs/InP droplet epitaxy quantum dots with their sub-Poissonian emission near 1550 nm are ideally suited for the realisation of this technology. To create the necessary on-demand photon emission at GHz clock rates, we develop a flexible pulsed optical excitation scheme, and demonstrate that the fast driving conditions are compatible with a low multiphoton emission rate. We show further that, even under these driving conditions, photon pairs obtained from the biexciton cascade show an entanglement fidelity close to 90\%, comparable to the value obtained under cw excitation. Using asymetric Mach Zehnder interferometers and our photon source, we finally construct a time-bin qubit quantum relay able to receive and send time-bin encoded photons, and demonstrate mean teleportation fidelities of 0.82±0.01, exceeding the classical limit by nearly 10 standard deviations.
@article{arxiv.2001.07073,
title = {GHz-clocked teleportation of time-bin qubits with a telecom C-band quantum dot},
author = {M. Anderson and T. Müller and J. Huwer and J. Skiba-Szymanska and A. B. Krysa and R. M. Stevenson and J. Heffernan and D. A. Ritchie and A. J. Shields},
journal= {arXiv preprint arXiv:2001.07073},
year = {2020}
}