Soutenance de thèse Mounir Abdkrimi - Modélisation de la chaîne de lecture et optimisation du traitement numérique sur FPGA pour les détecteurs supraconducteurs à inductance cinétiques

by Mounir Abdkrimi (LPSC)

Friday 3 Oct 2025, 10:00 → 12:00 Europe/Paris

Grand Amphithéâtre (LPSC Grenoble)

In the last two decades, Microwave Kinetic Inductance Detectors (MKIDs) have undergone significant development and have emerged as a promising candidate for detecting and studying millimeter wavelength photons in astronomy. These detectors are distributed-element superconductor resonators, featuring interdigitated capacitors and meander inductors sensitive to millimeter-waves due to the properties of superconductivity. They operate in the radio-frequency (RF) domain at temperatures near or below 100 mK. Thanks to the high quality factor of MKIDs, it is possible to connect a large number of them in series, each one with a unique self-resonant frequency, to a single transmission line. Readout electronics combining digital signal processing with radiofrequency (RF) and low-noise conditioning techniques have been developed in collaboration at the Laboratoire de Physique Subatomique et de Cosmologie (LPSC). These electronics have been implemented and utilized in several MKID-based instruments, including NIKA2, KISS, and CONCERTO. The latest generation of readout electronics, KID_READOUT, is capable of reading out a feedline coupled to 400 MKIDs, with their self-resonant frequencies distributed over a 1 GHz bandwidth. The field of millimeter-wave astronomy is evolving rapidly, driven by the upcoming generation of cameras with twice the pixel count. These next-generation cameras will enable deeper exploration of complex astrophysical phenomena, but they will also require the readout electronics to generate and analyze twice as many tones. At present, however, it remains unclear whether the existing KID_READOUT architecture can meet these new requirements. This uncertainty stems from a limited understanding of the readout chain, particularly regarding the key factors that constrain the scalability of the readout frequency multiplexing. This thesis addresses these challenges by thoroughly characterizing the current readout solution, KID_READOUT, with the goal of developing its first complete model. This model enables the identification of limiting factors, and paves the way for optimizations aimed at doubling the frequency multiplexing factor, thereby meeting the requirements of next-generation MKID-based instruments.