Time-bin and Polarization Superdense Teleportation for Space Applications

To build a global quantum communication network, low-transmission, fiber-based communication channels can be supplemented by using a free-space channel between a satellite and a ground station on Earth. We have constructed a system that generates hyperentangled photonic "ququarts'' and measures them to execute multiple quantum communication protocols of interest. We have successfully executed and characterized superdense teleportation---our measurements show an average fidelity of 0.94±0.02, with a phase resolution under 7° allowing reliable transmission of >10⁵ distinguishable quantum states. Additionally, we have demonstrated the ability to compensate for the Doppler shift, which would otherwise prevent sending time-bin encoded states from a rapidly moving satellite, thus allowing the low-error execution of phase-sensitive protocols during an orbital pass.