Practical quantum key distribution networks: a mini-review

Abstract Quantum key distribution (QKD) enables information-theoretically secure communication based on the laws of quantum physics. Although QKD remains an active area of research, ongoing commercialization efforts underscore its growing significance in modern physics and communication. This mini-review provides a brief overview of existing multi-user QKD networks and ongoing developments, with an emphasis on field tests. We examine different network architectures. In addition, we explore the prospect of photonic integrated circuits (PICs) and their current capabilities in QKD implementations. We also present various post-processing algorithms focusing on error correction (EC) and privacy amplification (PA), as well as implementations of these protocols in different experiments. Finally, we conclude by providing an overview of our quantum network and discussing setup choices from our recent field tests.