BEGIN:VCALENDAR VERSION:2.0 PRODID:Icfo X-PUBLISHED-TTL:P1W BEGIN:VEVENT UID:69d4b3e0b10eb DTSTART:20250407T080000Z SEQUENCE:0 TRANSP:OPAQUE LOCATION:ICFO Auditorium SUMMARY:ICFO | CARLOS PASCUAL CLASS:PUBLIC DESCRIPTION:With this Thesis\, we will focus on diverse technologies as wel l as techniques relevant for the development of secure communication syste ms based on Quantum Mechanics. This theoretical analysis involves the appl ication of diverse methodologies\, which represent formidable challenges f rom a purely analytical perspective\, as well as from a numerical stance. The contents of this manuscript are divided according to the nature of the particular technology under scrutiny.\nAs a first step\, we will provide a study of Quantum Key Distribution based on continuous variable states an d coarse-grained measurements. This inquiry is split according to two chap ters. In the first one\, a thorough description of our approach will be pr ovided\, as well as diverse outcomes regarding the addition of postselecti on techniques for an improved perfomance\; a study of optimization in infi nite dimensions\, as well as results in the finite regime under collective attacks. In the second part\, we will observe how performing a full discr etization on the measurements grants not only full security against any ad versary allowed by Quantum Mechanics\, but also a new formalism via entrop y accumulation approaches that permits the analysis of the statistical flu ctuations that emerge when only finite statistics are accessible.\nThis di scussion \; will be followed by a study of Quantum Random Number Gener ation according to a semi Device Independent perspective where the assumpt ions on the experimental setups are limited. Our discussion will be based on using a trusted measurement and imposing a bound on the corresponding e xpectation value -- which requires an adaption from the well-known asympto tic limit to the the finite case in order to prevent emerging security pit falls. This examination is completed with a thorough security proof agains t general attacks and diverse results in the finite regime.\nTo conclude\, this Thesis finishes with an assessment of Quantum Key Distribution for l arge networks based on classical Internet models\, which provides insights on the scalability and optimality conditions of Quantum Communications ac cording to the density of users and their connections. In particular\, thi s indagation is mainly based on continuous variable systems\, albeit anoth er approach grounded on discrete variables is also added to the model in o rder to enhance its performance.\n \;\nMonday April 7\, 10:00 h. ICFO Auditorium \nThesis Director: Prof. Dr. Antonio Ací\;n and Dr. Stefa n Bä\;uml DTSTAMP:20260407T073600Z END:VEVENT END:VCALENDAR