Modeling of silicon quantum bits ; Modélisation de bit quantique en technologie de silicium

Noise sources are one of the critical factors that determine the performance of qubits in quantum computing applications. Noise sources refer to any external factors that can cause errors or decoherence in a qubit. In this thesis, we have simulated these effects in the case of a hole spin qubit in Silicon-On-Insulator (SOI) technology.Charge fluctuators are one of the major sources of noise in hole spin qubits. The presence of moving charges can introduce fluctuations in the electric field around the hole. Charge fluctuators may arise from impurities or defects in the oxide layers in the vicinity of silicon regions. They can induce random changes in the energy levels, wavefunctions and [dollar]g[dollar]-factors of the hole spin, causing errors or decoherence in the qubit.This makes it essential to study the impact of charge fluctuators on hole spin qubit. We simulate a quantum dot confining a single hole. The confinement is defined by electrostatic gates on a silicon nanowire channel. Our goal is to describe the qubit as realistically as possible compared to technologies which were recently developed and characterized. Our simulation takes into account the relaxation and the dephasing of the hole spin over time by combining Poisson and time-dependent Schr{"o}dinger equations to model a classical random telegraph signal. Our approach is able to describe the combined effects of fluctuating electric fields and spin-orbit coupling on the spin dynamics, without any free parameter.We show that the well-known two-level model effectively describes the dephasing time [dollar]T_2[dollar] over a broad range of frequencies [dollar]u[dollar] of the telegraph signal. When [dollar]u[dollar] is low, the decoherence is determined by the short time behavior of the spin precession phase which is then characterized by a non-Gaussian distribution, the coherence of the phase is lost as soon as the fluctuator changes state. The Gaussian description is only accurate above a threshold frequency [dollar]omega_{th}[dollar], when the ...