Enabling Technologies for Free Space Quantum Cryptography

In this SBIR project we aim to exploit a new invention in quantum cryptography to secure free-space optical links and networks. Unlike the techniques based on single-photon states that are limited to low bit rates and short distances, our approach is based on coherent states emitted by ordinary lasers, permitting scaling to high speeds and deployment over realistic distances. We have already demonstrated single channel speeds of 622 Mb/s over 550 km distance in optical fiber. We aim to scale this technology to 2.5 Gb/s over free-space distances spanning LEO and MEO spacecrafts and ground networks. We believe this technology is also applicable to encrypting data over emerging commercial free-space-optics (FSO) networks. Specifically, in Phase II we will perform the following tasks: 1) Improve security with expanded electronics in the 622 Mb/s system. 2) Improve performance for up to 1 km free-space reach. 3) Add protocols and control circuitry to allow for fully automated operation. 4) Implement an on-demand key loading feature. 5) Build and characterize a working prototype suitable for trials in a deployed free-space system at the AFRL. As an option we will deliver a system working at 1-2 Gb/s.