Quantum teleportation and entanglement distribution over 100-kilometre free-space channels

TL;DR

This paper demonstrates long-distance quantum teleportation and entanglement distribution over 97 km free-space channels, achieving high fidelity and violating Bell inequalities, advancing towards global quantum networks.

Contribution

It reports the first long-distance quantum teleportation over a 97-km free-space channel and entanglement distribution over a high-loss channel, with high fidelity and Bell inequality violation.

Findings

Achieved 80.4% fidelity in teleporting six quantum states.

Distributed entanglement over channels with 66-85 dB loss.

Violated Bell inequality after entanglement distribution.

Abstract

A long standing goal for quantum communication is to transfer a quantum state over arbitrary distances. Free-space quantum communication provides a promising solution towards this challenging goal. Here, through a 97-km free space channel, we demonstrate long distance quantum teleportation over a 35-53 dB loss one-link channel, and entanglement distribution over a 66-85 dB high-loss two-link channel. We achieve an average fidelity of {80.4(9)}% for teleporting six distinct initial states and observe the violation of the Clauser-Horne-Shimony-Holt inequality after distributing entanglement. Besides being of fundamental interest, our result represents a significant step towards a global quantum network. Moreover, the high-frequency and high-accuracy acquiring, pointing and tracking technique developed in our experiment provides an essential tool for future satellite-based quantum communication.