Analysis of a Vacuum Beam Guide for Quantum Communications

Current solutions for quantum communication channels such as telecom fibers and satellite relays face significant issues such as high loss and disrupted transmission. Huang et al. have introduced a vacuum beam guide as a promising new solution designed to provide a low-loss and stable quantum channel, with less than 10^-4 dB/km loss not subject to atmospheric variability. This system uses a periodically spaced array of lenses within an evacuated tube to propagate a coherent electromagnetic field over long distances with minimal loss. The initial proposal is limited to analyzing a confocal vacuum beam guide and calculates only absorption loss and a preliminary estimate of alignment loss. Our analysis further examines the performance of a generalized class of vacuum beam guide configurations with the inclusion of physical imperfections using computer optics simulations. These simulations were developed into software tools that allow for detailed evaluation and optimization of different vacuum beam guide configurations. By identifying a configuration’s alignment tolerances, this work enables the development of a system that is suitably insensitive to realistic constraints. These results advance the vacuum beam guide closer to potential implementation as a quantum communication channel and contribute to the realization of reliable, continental-scale quantum communications with low loss and high throughput.