Abstract
The general purpose of the lecture, presented in the first lesson, was to provide a general introduction to this new research theme, posing a number of questions to which the year's lecture and those of subsequent years will seek to provide more precise answers:
- How can we interpret the theory's formalism, and in particular what is an ideal measurement in quantum physics?
- What is quantum entanglement and its link with non-locality?
- How can we precisely quantify the degree of entanglement of a system in different cases (bi- or multi-part systems, pure cases or statistical mixtures)?
- How can we describe the loss of entanglement in large quantum systems (decoherence)?
- How can we protect "good" entanglement (that which we want to control and use) from "bad" entanglement (that which involves the system and its environment and causes decoherence)?
- How can we use entanglement to communicate, share information and compute more efficiently or faster than by conventional means?
- How can these operations be carried out experimentally (choice of qubit systems, realization of elementary operations, possibility of integrating a large number of bits, etc.)?
In all these questions, the notion of quantum entanglement, which Schrödinger considered to be the very essence of quantum theory, plays a fundamental role. This notion has been defined in this first lecture, illustrating it with simple examples from atomic physics.
