Experimental single photon exchange along a space link of 7000 km

TL;DR

This paper demonstrates the successful exchange of single photons over a 7000 km space link from a MEO satellite to ground, advancing quantum communication capabilities on a global scale.

Contribution

It reports the first single photon exchange from a MEO satellite at over 7000 km, using corner cube retro-reflectors, enabling long-distance quantum communication tests.

Findings

Single photon exchange achieved over 7000 km distance.

Mean photons per pulse limited to 1, with detection rate of 3 cps.

Feasibility of quantum communication from MEO satellites demonstrated.

Abstract

Extending the single photon transmission distance is a basic requirement for the implementation of quantum communication on a global scale. In this work we report the single photon exchange from a medium Earth orbit satellite (MEO) at more than 7000 km of slanted distance to the ground station at the Matera Laser Ranging Observatory. The single photon transmitter was realized by exploiting the corner cube retro-reflectors mounted on the LAGEOS-2 satellite. Long duration of data collection is possible with such altitude, up to 43 minutes in a single passage. The mean number of photons per pulse ({\mu}sat) has been limited to 1 for 200 seconds, resulting in an average detection rate of 3.0 cps and a signal to noise ratio of 1.5. The feasibility of single photon exchange from MEO satellites paves the way to tests of Quantum Mechanics in moving frames and to global Quantum Information.