Simulation of Ground-Satellite Quantum Key Exchange Using a Dedicated Atmospheric Free-Space Testbed

The University of Canberra and its research collaborators have established a dedicated free-space laser communications test-bed between a national telecommunications facility and four selected monitoring sites at distances ranging from 4 to 47 km. This test-bed is currently being used to simulate and characterize the free-space quantum channel along which secure quantum key exchanges could take place between earth stations and low earth orbit satellites, the latter acting as global key couriers. We present the results of these trials conducted under a variety of atmospheric conditions. We use the results to estimate error rates and secure key exchange rates for ground/satellite key exchange systems employing weak Poissonian pulses with more stringent security requirements than are sometimes quoted