Review of representative free-space quantum communications experiments

Abstract

Worldwide free-space quantum communications (QC) experiments over the past decade are reviewed and discussed with attention to technological QC trends. Experiments reported in the open literature have included those conducted along horizontal propagation paths of varying distances, as well as communication paths from ground-to-aircraft, ground-to-space, and demonstrations in the laboratory. Available data characterize propagation distances, transmission speeds, quantum key distribution (QKD) protocols, and quantum bit error rates (QBER). While fiber optic implementations of quantum communications technologies are currently being tested for communications infrastructure it is important to also consider that free-space quantum communications will play an important role in securing such applications as earth-to-satellite, end of line connects, and defense implementations.