Manufacturing precise quantum computers with small errors in quantum operations, long coherence times, and low power consumption is the most important challenge in modern nanoelectronics. To understand the operating modes of such calculators in detail, both the optimal arrangement of the qubit system within the structure and changes in its magnetic properties must be comprehensively investigated. In this paper, the behaviour of one and two phosphorus atoms on the surface of silicene is studied using quantum mechanical non-collinear calculations, which consider spin–orbit coupling. The magnetization and ion charge on phosphorus atoms for substitution and different adsorption positions are determined. The optimal positions, binding energies, and activation barriers for the diffusion of adsorbed phosphorus in the presence and absence of a primary adsorbed or substituting phosphorus atom are also established. Overall, the results of this work have important implications for researchers and technologists in the manufacture of Si:P based quantum computers.