Future networking of quantum processors such as quantum computers will be realized using fiber optic interconnects. It is advantageous if these same fibers can carry high-rate classical communications, but the relatively high power of classical signals can corrupt the sub-photon quantum signal. This project will investigate means of allowing quantum and high-rate classical signals to co-exist on the same fiber line. This will be accomplished by co-optimization of the classical and quantum channels, including their wavelengths and modulation formats. The ability of various tools to allow stronger, thus higher rate, classical signals to co-exist with quantum signals will be analyzed, including using commoditized components as well as emerging technologies. We will analyze the expected joint performance via both modeling and experimental data collection. This analysis will allow us to compare the performance of different designs and compose a series of design rules for building such systems, as well as a list of enabling technologies with their estimated system-level impact. A suggested design suitable for a Phase-II demonstration will be evaluated. If successful this project would advance the ability of quantum networks to host both high- quality quantum signals and high data-rate traditional signals over long distances. This would have multiple effects including increasing the number of links that are suitable for being used in quantum applications, reducing the cost of retro-fitting quantum-links into existing lines, and advancing the general field quantum networks (which need substantial classical communications to operate). We expect this will be of interest to future scientific applications, where inter- connected high-performance computing systems are expected to bring to bear quantum processing to achieve an extreme speed-up of specialized tasks.
