The Cosmic Microwave Background (CMB) radiation is a relic emission from 380 000 years after the Big-Bang. The small temperature fluctuations, resulting from quantum perturbation generated in the early Universe, contain precious information about the physics of the primordial Universe and the cosmological parameters describing in the framework of the standard cosmological model, the dynamics of the Universe and its physical content. Several experiments, including the recent Planck satellite mission of ESA have recently measured those perturbations with high accuracy, leading to per cent precision on the determination of cosmological parameters. The next objective of the community is to measure the polarization of the CMB and in particular to detect and constrain the B-mode (negative parity) pattern on the sky, which are the imprint of primordial gravitational waves generated during the inflation period. The LiteBIRD mission has recently been proposed to the Japanese space agency (JAXA) and has been selected at the end of phase A-1. The main goal of the mission is to measure the primordial B-mode at large angular scale of the sky with an accuracy on r (the tensor-to-scalar ratio) of less than 10^-3. The LiteBIRD experiment includes a contribution from Europe and the USA, and the mission is currently under study for a phase A with the French space agency CNES.

The measurement of B-mode polarization is complex and requires an unprecedented control of systematic effects originating from the instrument. The study of potential systematic effects has an impact on the definition of the mission configuration and observation strategy. The PhD student will simulate instrumental effects and their impact of data and develop analysis techniques to mitigate eventual residual contributions. In particular, he will focus on the modelling of the have wave plate (HWP), a critical optical element of LiteBIRD. By modulating the polarization signal the HWP allows to removes many spurious effects but on the other end possible defects might induce artefacts in the data. Those studies will be perform within a large consortium including researchers in Europe and Japan.