Integrated Photonics for Quantum-Secure Links : Abstract

Quantum Key Distribution (QKD) has emerged as a leading cryptographic technology for establishing communication links resilient to quantum-computing threats [1] . It establishes information-theoretically secure keys between remote parties via satellite, free-space, or fiber-based channels. Current QKD implementations largely rely on discrete optical components, which limit system miniaturization and increase energy demands. As demand for QKD has grown and the technology has matured, substantial hardware advancements have followed. To further reduce costs and enhance reliability, photonic integrated circuits (PICs) have been introduced [2] . By integrating optical, electronic, and optoelectronic elements into compact modules, PICs significantly decrease system size, power consumption, and heat dissipation. Recent progress in hermetic sealing and bonding has enabled the production of robust, ready-to-use modules, enabling large-scale deployment at lower cost. In parallel, advances in material platforms have expanded the range of available PIC components, each offering unique performance advantages for quantum applications [3] .