Experimental verification of the feasibility of a quantum channel between Space and Earth

TL;DR

This study demonstrates the first experimental setup for quantum communication between a satellite and Earth, confirming the feasibility of space-based quantum channels for future quantum information applications.

Contribution

We implemented and tested a scheme for single-photon exchange between a satellite and ground station, simulating space-to-earth quantum communication for the first time.

Findings

Successful detection of single-photon signals from a satellite in low-earth orbit

Validation of quantum channel feasibility between space and ground

Potential for future quantum communication networks in space

Abstract

Extending quantum communication to Space environments would enable to perform fundamental experiments on quantum physics as well as applications of quantum information at planetary and interplanetary scales. Here, we report the first experimental implementation of a scheme for single-photon exchange between a satellite and an Earth-based station. We built an experiment that mimics a single photon source on a satellite, exploiting the telescope at the Matera Laser Ranging Observatory of the Italian Space Agency to detect the transmitted photons. Weak laser pulses, emitted by the ground-based station, are directed towards a satellite equipped with cube-corner retroreflectors. These reflect a small portion of the pulse, with an average of less-than-one photon per pulse directed to our receiver, as required for the faint-pulse quantum communication. We were able to detect returns from satellite Ajisai, a low-earth orbit geodetic satellite, whose orbit has a perigee height of 1485 km.