Quantum signals and circuits

In computer science, the notion of the bit, an elementary unit of information, is often discussed in abstract terms, dissociated from a particular implementation. This is the case, for example, when discussing Boolean operations. This is justified by the universality of most algorithms and communication protocols, which are largely independent of representation details. However, when it comes to the ultimate limits of information processing parameters such as throughput, data volume, energy consumption, latency, etc., the physical nature and mutual interactions of the information-carrying degrees of freedom become crucial. This lecture explores the physics of electronic devices and systems that process information at the most elementary level : one and zero are represented by the presence and absence of an excitation quantum of electromagnetic fields in the circuit. This year's lessons were an introduction to this field, limited to situations where quantum processing of signals and circuits is the most direct continuation of classical processing.