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Offre de stage : Machine learning quantum-assisted cryptography

Laboratoire d’accueil : Institut de Physique Théorique, CEA-Saclay
Responsable du stage : Nicolas Sangouard
 
Description de la mission
Quantum-assisted cryptography provides guarantees for secure communications that cannot be achieved with known classical technologies. Yet, its security relies on the assumption that the devices used to produce the key are trusted — they carry out precisely the operations foreseen by the protocol. This assumption is hard to meet in practice and the security guarantees can be corrupted in case it is not perfectly satisfied, as demonstrated recently by hacking experiments. The aim of device-independent quantum key distribution (DIQKD) is to overcome this problem — it provides security even when the devices are largely uncharacterised and treated like black boxes. While DIQKD provides qualitative improvement in safety, its implementation is demanding on experimental resources and theoretical understanding.
 
The aim of this internship is to help developing the theoretical groundwork needed to implement DIQKD with optical elements. This will be achieved by both improving the security proofs and finding optimal optical implementation of the protocol. In particular, the successful candidate will help devising new security proofs with improved critical detection efficiency bounds using the knowledge of individual correlation functions instead of global Clauser–Horne–Shimony–Holt Bell score. He/she will show how to use squeezing operations, linear optical elements and photon counting techniques to observe experimentally targeted correlation functions, taking into account realistic noise and loss. This optimal optical setup will be obtained by combining generic simulation of non-Gaussian quantum optics with simulated annealing and reinforcement learning.
 
Niveau de qualification demandé : Master 1/2 Physique Quantique