Combining quantum key distribution with chaotic systems for free-space optical communications

In this work, we propose a free-space optical (FSO) communication system that combines chaotic communications with quantum key distribution (QKD) to achieve greater security and range compared to existing FSO techniques such as N-slit interferometers. We utilize Lorenz chaotic transmitter and receiver models, which are inherently auto-synchronizable, to generate chaotic signals used as data carriers. Data are transmitted securely over a classical channel using the Lorenz chaotic communication system, while a quantum channel is used for securely exchanging critical synchronization parameters via a combination of QKD and public-key cryptography protocols. Because FSO communications have been utilized by spaces agencies including NASA and ESA, we provide a concept of operations for a space mission combining chaotic communications and QKD to achieve an end-to-end encrypted deep-space optical communications link. Our experimental work includes successful real-time transmission of high-resolution single-spectral and multi-spectral images, measurement of bit-error-rate over a range of noise levels, and an evaluation of security and robustness of transmissions with dynamic reconfiguration of the chaotic systems.