Damien Stucki

Integrating Quantum Key Distribution (QKD) into optical metropolitan networks is a crucial step toward bringing quantum technologies into existing telecommunication fiber infrastructures. However, current state-of-the-art solutions still face major challenges, including their sensitivity to classical noise, especially spontaneous Raman scattering, limited transmission distances, and performance degradation under heterogeneous network conditions. In this work, we present a new QKD system operating in the O-band at 1295.56 nm, where the effect of the main noise sources is significantly reduced. Combined with narrow spectral filtering at the receiver, without the need for active temperature control, the system shows strong robustness across a wide range of dense wavelength division multiplexing scenarios, making it a practical option for real-world deployment. We validate its performance through extensive testing and demonstrate stable key generation while coexisting with different classical traffic conditions, with total launch powers of up to 17 dBm. These results represent an important step forward for the integration of QKD into existing fiber networks, supporting the path toward secure quantum communications at scale.

In security applications, it is necessary to use random numbers with the highest possible entropy. Quantum Random Number Generators (QRNG) are most suitable for creating such numbers due to the non-deterministic nature of quantum physics. In this work we present the different steps of the construction of a new design for a high-speed QRNG. Furthermore, in order to make our QRNG suitable for use in security applications, we explain the steps we are taking to make it conform to security standards. Such standards exist and define guidelines for the design of classical Random Number Generators. However, for QRNG, it is necessary to make adaptations, which requires additional work in its design, realization and evaluation with respect to security standards.