Relatore : Eleni DIAMANTI

Co-relazione : GRANGIER, Philippe (UMR 8501, Groupe Optique Quantique / IOTA

Development of advanced continuous-variable quantum key distribution systems

A central application in this field is quantum key distribution (QKD), which allows two parties to share a secret key that can be subsequently used for message exchange, even in the presence of eavesdroppers with unlimited power. This is impossible by classical means. Continuous-variable (CV) QKD, where the key information is encoded on the quadratures of the electromagnetic field, is particularly appealing from a practical point of view in that it only requires off-the-shelf telecom components for their implementation as the PhD thesis supervisors have shown in fibre-optic long-distance experiments [Nature Photon. 7, 378 (2013)]. Since these results, the work on CV-QKD in our group has focused on the photonic and network integration of such systems.
In this doctoral project, we propose to address the many challenges that are found on the way to the development of advanced cost-effective telecom network integrated CV-QKD systems that are ready to operate in a deployed optical fibre environment. These include the conception and implementation of solutions for a system operation in the so-called local Local Oscillator configuration, with suitable modulation schemes (and associated security proofs), as well as with adapted high-speed electronics. The thesis work will also include the characterization of photonic integrated CV-QKD transmitter and receiver chips on both the silicon and indium phosphide platforms, and their use for secret key generation. This will be crucial for future scalable solutions for QKD systems.