Silicon/Germanium spin qubits have made outstanding progress in the past two years [Nature 591, 580 (2021); arXiv:2202.09252]. In these devices, the elementary information is stored as a coherent superposition of the spin states of an electron in a Si/SiGe heterostructure, or of a hole in a Ge/SiGe heterostructure. These spins can be manipulated electrically owing to the intrinsic spin-orbit coupling, and get entangled through exchange interactions, allowing for the implementation of a variety of one- and two-qubit gates required for quantum computing and simulation. Grenoble is developing original spin qubit platforms on Si and Ge, and holds various records in spin lifetimes [arXiv:2201.08637, to appear in Nature Nano] and spin-photon interactions [arXiv:2206.14082]. The aim of this PhD project is to support the progress of these advanced quantum technologies with state-of-the-art analytical and numerical modelling. For that purpose, the CEA is, in particular, developing the TB_Sim code, able to describe very realistic qubit structures down to the atomic scale if needed. The spin manipulation and entanglement, the response to noise and disorder (decoherence), and the interactions with photons (circuit quantum electrodynamics) will notably be addressed during the PhD. This PhD is fully funded by a grant from the french ANR. The candidate will have the opportunity to interact with a lively community of experimentalists working on spin qubits at CEA and CNRS.