Physical-layer Impairment in Integrating QKD to Optical Fiber Networks

Abstract
Quantum Key Distribution (QKD) is currently the most mature quantum technology, transitioning from laboratory research to real-world secure communication
applications. However, the deployment of dedicated infrastructure for QKD remains prohibitively expensive. A more practical and scalable approach is to integrate QKD with existing optical communication networks, leveraging the current infrastructure to reduce deployment costs. In this work, we explore the primary challenges associated with such integration. As QKD systems are expected to operate alongside classical data traffic—especially in dense, resource-constrained optical networks—it becomes essential to understand and mitigate the interactions between quantum and classical signals. A central focus of our study is the physical-layer impairments resulting from the co-propagation of quantum and classical signals within the same optical fiber. In addition, we examine the impairments introduced by the switching components in the network, such as optical switches and reconfigurable optical add-drop multiplexers (ROADMs), which can further degrade quantum signal quality and pose additional hurdles for seamless QKD integration.

Bio
Dr. Rui Lin received her Ph.D. in Communication Systems from KTH Royal Institute of Technology in 2017, where she also held a postdoctoral position focusing on high-speed optical communication systems. Since 2019, she has been a researcher at Chalmers University of Technology, where she broadened her expertise into quantumcommunication and networks. Her current research lies at the intersection of classical and quantum networking. She currently leads a research group of four researchers focused on the emerging field of quantum networks.