BEGIN:VCALENDAR VERSION:2.0 PRODID:Icfo X-PUBLISHED-TTL:P1W BEGIN:VEVENT UID:69d255b6656ae DTSTART:20231220T100000Z SEQUENCE:0 TRANSP:OPAQUE LOCATION:ICFO Auditorium SUMMARY:ICFO | JENNIFER ALDAMA CLASS:PUBLIC DESCRIPTION:Being able to secure confidential information is imperative in today&rsquo\;s society\, but advancements in quantum technologies pose a p otential threat. In response\, researchers are developing technologies bas ed on quantum mechanics\, such as quantum key distribution (QKD)\, in part icular continuous-variable QKD (CV-QKD)\, which is emerging as a promising solution due to its compatibility with classical network infrastructures. However\, current systems remain bulky and costly\, limiting their widesp read adoption. To address this challenge\, the miniaturization and integra tion of QKD systems into monolithic photonic integrated circuits (PICs) ha ve the potential to accelerate adoption across a broader market. This is d ue to the anticipated reductions in size\, power consumption\, production costs and overall system complexity.\nThis work presents four pulsed Gauss ian-modulated coherent state (GMCS) CV-QKD systems based on discrete compo nents and\, in the last case\, a PIC. The thesis begins with a modular sys tem utilizing discrete components\, such as phase and amplitude modulators . Notably\, this prototype eliminates the need for phase locking\, as the same laser serves as both a local oscillator and the source for generating quantum signals. The system mitigates Rayleigh backscattering by employin g two channels\, one for transmitting light and the other for transmitting coherent states. Demonstrations indicate its operability over metropolita n distances.\nIn the second approach\, the system showcases the paralleliz ation of CV-QKD signals and the coexistence of multiple quantum signals wi th a classical signal\, spatially multiplexed through a multicore fiber (M CF). In this scenario\, two lasers are employed\, with one emitting the fr equency locking signal propagating along one of the MCF&rsquo\;s core.\nTh e third proposal introduces a simplified CV-QKD transmitter (TX) that elim inates the need for a phase modulator in the GMCS generation. This system leverages the random properties of a distributed feedback (DFB) laser oper ating in the gain-switching (GS) mode. The study demonstrates the applicab ility of our proposed compact TX for GMCS generation in CV-QKD and its fea sibility for integration into a metropolitan network.\nFinally\, we descri be and characterize an InP-based PIC TX tailored for CV-QKD applications. System-level proof-of-principle experiments are conducted using a shared l aser approach with a pulsed GMCS CV-QKD protocol over an 11 km optical fib er channel. The results indicate potential secret key rates of 52 kbps in the asymptotic regime and 27 kbps in the finite size regime\, highlighting the capabilities of the proposed PIC design and\, more broadly\, the prop erties of InP technologies for monolithic integration of CV-QKD systems. A ll the proof-of-principle experiments outlined in this dissertation contri bute significantly to the field of miniaturizing CV-QKD systems.\nThesis D irector: Prof Dr. Valerio Pruneri &\; Dr. Sebastiá\;n Etcheverry Cabrera DTSTAMP:20260405T122942Z END:VEVENT END:VCALENDAR