Michel Devoret is a professor of physics and applied physics at Yale University. Before taking his position at Yale he was at Saclay where he started the quantum mechanical electronics group with Daniel Esteve and Cristian Urbina. Michel Devoret has received the Ampere Prize of the French Academy of Science (together with Daniel Esteve), the Descartes-Huygens Prize of the Royal Academy of Science of the Netherlands and the Europhysics-Agilent Prize of the European Physical Society (together with Daniel Esteve, Hans Mooij and Yasunobu Nakamura). His main achievements are the measurement of the traversal time of tunneling, the invention of the single electron pump (now the basis of a new standard of capacitance), the first direct observation of the charge of Cooper pairs, the first measurement of the effect of atomic valence on the conductance of a single atom, and very recently, the development of a high-coherence superconducting quantum bit. This work is of great importance for the new field of Quantum Computers. The lectures focused on issues related to devices relevant for the realization of Quantum Computers, where quantum coherence is the central issue.