Quantumentanglementisanessentialresourceinquantuminformationprocessing and its generation, manipulation and distribution between distant parties are key challenges in the pursuit of a global quantum network. In light of this goal, high-dimensional encoding has been shown to improve robustness and channel capacities in secure quantum communications. The transmission of genuine high-dimensional entanglement under real-world atmospheric link conditions, however, is an ongoing experimental challenge. Here, I give an overview of our eorts towards implementing high-dimensional quantum communication protocols in long-distance free-space links. I report on a proof-of-concept experiment in which we, for the rst time, use energy-time and polarization hyperentanglement to distribute 4-dimensional entanglement via a 1.2-km-long intra-city free-space link. I discuss how this approach can be adapted for high-dimensional free-space QKD and report on the progress of ongoing experiments.
1. Steinlechner, F. et al. Distribution of high-dimensional entanglement via an intra-city free-space link. Nat. Commun.8, (2017).