On the Polarization Analysis of Optical Beams for Use in Quantum Communications between Earth and Space

In this work we will address the transformation of the polarization state of single photons during the transmission along a Space channel and the measures to correct them in order to accomplish Quantum Communication (QC) between Space and Earth. An open issue in space scale QC is the preservation of polarization states by the telescope and all the involved moving optical components, as well as ensuring the alignment of the polarization basis between the orbiting sender and receiver on Earth. In the following, we will treat in detail this crucial aspect, by modelling the measurement of the polarization properties of the quantum channel, expressed by its Mueller matrix, in the experimental conditions of Ref. [12] with the addition of the control of the outbound state of the photons and the measure of the polarization state of the inbound beam.