EFT of Open Systems : Density Matrices and the Operator Formalism (1/4)
By Enrico Pajer
Appears in collection : 2026 IHES Summer School – Cosmological Correlators
The first lecture introduces the foundational concepts of open quantum systems in the operator language. Topics include: - Density matrices and the distinction between pure and mixed states, - Entanglement, coarse graining, and the origin of entropy in open systems, - Quantum master equations and effective non-unitary evolution, - The Lindblad equation and Markovian dynamics, - Completely positive and trace-preserving (CPTP) maps and their physical interpretation. The emphasis is on understanding how effective dissipative dynamics emerge when unobserved degrees of freedom are integrated out.
