Distribution of genuine high-dimensional entanglement over 10.2 km of noisy metropolitan atmosphere

TL;DR

This paper demonstrates the successful distribution of genuine high-dimensional entanglement over a 10.2 km noisy free-space channel, confirming the feasibility of high-dimensional quantum communication in metropolitan environments.

Contribution

It introduces an improved discretisation and entanglement certification scheme for high-dimensional time-bin setups, validating genuine entanglement in a long-range free-space experiment.

Findings

Confirmed genuine high-dimensional entanglement over 10.2 km

Validated improved certification scheme for high-dimensional entanglement

First demonstration of such entanglement in a metropolitan free-space channel

Abstract

In a recent quantum key distribution experiment, high-dimensional protocols were used to show an improved noise resistance over a 10.2 km free-space channel. One of the unresolved questions in this context is whether the communicating parties actually shared genuine high-dimensional entanglement. In this letter we introduce an improved discretisation and entanglement certification scheme for high-dimensional time-bin setups and apply it to the data obtained during the experiment. Our analysis answers the aforementioned question affirmatively and thus the experiment constitutes the first transmission of genuine high-dimensional entanglement in a single degree of freedom over a long-range free-space channel.