There are five appendices. The first, Appendix A, supplements the discussion of Section 1.2 of Chap. 1. The next two appendices, B and C, contain technical details needed for Chap. 7 in regard to laterally coupled quantum dots. The last two appendices, D and E, provide some fundamental information related to the Bloch sphere, rotations, unitary groups, evolution matrices and applications to SQUID (Chap. 9) and NMR (Chap. 10).