Multi-photon entangled states are a crucial resource for many applications in quantum information science. Semiconductor quantum dots offer a promising route to generate such states by mediating photon-photon correlations via a confined electron spin, but dephasing caused by the host nuclear spin environment typically limits coherence (and hence entanglement) between photons to the spin T2∗ time of a few nanoseconds. We propose a protocol for the deterministic generation of multi-photon entangled states that is inherently robust against the dominating slow nuclear spin environment fluctuations, meaning that coherence and entanglement is instead limited only by the much longer spin T2 time of microseconds. Unlike previous protocols, the present scheme allows for the generation of very low error probability polarisation encoded three-photon GHZ states and larger entangled states, without the need for spin echo or nuclear spin calming techniques.
@article{arxiv.1706.02486,
title = {Protocol for generating multi-photon entangled states from quantum dots in the presence of nuclear spin fluctuations},
author = {Emil V. Denning and Jake Iles-Smith and Dara P. S. McCutcheon and Jesper Mork},
journal= {arXiv preprint arXiv:1706.02486},
year = {2018}
}