Title: 

Optimization Problems in Semi-Device-Independent Quantum Key Distribution Security Proof

Abstract: 

Quantum Key Distribution (QKD) is a well-established field of Quantum Information Theory with the promise of information theoretic secure key distribution protocols. Within this field, semi-Device Independent QKD address the challenge of providing the same security guarantee while giving no constraints on one party other than the laws of Quantum physics. In this master thesis, we walk step by step through a complete security proof, from the theoretical part to the numerical optimization. Although the results were inconclusive, the work highlighted challenges and area of development for the field.

Title: 

Multi-time statistics in open quantum systems: general definition and connection with non-classicality

Abstract:

More than a century after the advent of quantum theory, the question of which properties and phenomena are genuinely quantum—meaning that they cannot be replicated by any classical theory—remains a subject of active investigation. In this talk, we will explore how and to what extent non-classicality can be rigorously associated with specific behaviors in the evolution of open quantum systems subjected to sequential measurements over time. We will first revisit the general framework for defining multi-time correlators in open quantum systems and consider the Kolmogorov consistency conditions as the characterizing feature of classical stochastic processes. We will then discuss some recent findings that relate the emergence of non-classicality to the dynamics of quantum coherences within the system, or to quantum correlations between the system and its environment, depending on whether the underlying process is Markovian or non-Markovian.