Satellite-To-Earth Quantum Key Distribution via Orbital Angular Momentum
Ziqing Wang, Robert Malaney, Benjamin Burnett
Abstract
In this work, we explore the feasibility of performing satellite-to-earth quantum key distribution (QKD) using the orbital angular momentum (OAM) of light. Because of the fragility of OAM states the conventional wisdom is that turbulence would render OAM QKD nonviable in a satellite-to-earth channel. However, based on detailed phase screen simulations of the anticipated atmospheric turbulence we find that OAM QKD is viable in some system configurations, especially if quantum channel information is utilized in the processing of postselected states. More specifically, using classically entangled light as a probe of the quantum channel, and reasonably sized transmitter-receiver apertures, we find that nonzero QKD key rates are achievable on sea-level ground stations. We also determine the turbulence conditions under which the QKD key rate becomes effectively zero. Without using classical light probes, OAM QKD is relegated to high-altitude ground stations with large receiver apertures. Our work uses a quantitative assessment of the performance of OAM QKD from satellites to determine under what circumstances the much-touted higher dimensionality of OAM can be utilized in the context of secure communications.