In 1965 and later revised in 1975, Gordon Moore observed that the number of transistors was doubling every 24 months and would continue to do so. Unfortunately the shrinking of transistors is reaching its limits and has already started to slow down. For this reason new materials and devices has been introduced to continue the scaling of digital electronics performance and efficiency. In particular, the QCA (Quantum-dot Cellular Automata) technology is one of the most promising thanks to a lower power consumption, compatibility with CMOS (Complementary Metal Oxide Semiconductor) fabrication process and their non-volatile nature. Molecular and magnetic QCA are two implementation alternatives of this technology.