An Overview of Applications: Yesterday, Today, and Tomorrow

This chapter gives a concise overview about a number of specific physical problems, which are of recent, current, and possibly future interest, problems that can be ideally dealt with in terms of the nonequilibrium Schwinger–Keldysh Green’s functions technique developed at a formal level in Parts I and II. Accordingly, this chapter aims at providing a synthetic demonstration of the versatility of the Schwinger–Keldysh technique, especially in the view of possible future applications to scientific problems as well as to technological issues. In particular, it considers the main features associated with closed and driven open quantum systems, spectroscopic problems related to pump and probe photoemission, metastable photo-induced superconductivity, dynamics induced by quenches and rumps in “closed” quantum systems with emphasis on thermalization, and driven “open” quantum systems with emphasis on dissipation. A more detailed treatment of these topics is deferred to the following chapters.