The quantum repeater cell is a basic building block for a quantum network, as it allows to overcome the distance limitations due to unavoidable fiber loss in direct transmission. We demonstrate the implementation of a quantum repeater cell, based on two free-space coupled 40Ca+ ions in the same trap that act as quantum memories. We demonstrate the asynchronous generation of atom-photon and photon-photon entanglement by controlled emission of single photons from the individually addressed ions and entanglement swapping. We discuss the fidelity as well as the scaling of the generated rate.
@article{arxiv.2312.14805,
title = {Quantum repeater node with free-space coupled trapped ions},
author = {Max Bergerhoff and Omar Elshehy and Stephan Kucera and Matthias Kreis and Jürgen Eschner},
journal= {arXiv preprint arXiv:2312.14805},
year = {2024}
}