摘要： In the previous chapters of this book, we have discussed the consequences of quantum mechanics on the properties of solid state electrons mostly on the single or two particle level. This revealed the important influence of the phase of the electronic wave functions in mesoscopic electronic transport and a general understanding of the optical properties of solids, where the interaction between the electrons led only to relatively simple modifications such as the excitonic binding energy ERyd,X or the dielectric constant of the material ε. In addition, we have learned how to gain an unprecedented control of the quantum mechanical properties, including the dynamics, for single-electron and two-electron systems in spin qubits or in many-particle states in superconducting qubits. There, the electron-electron interaction was mostly used as an exchange coupling or as a classical repulsive energy for read-out.