Lecture
This lecture covers functional methods, focusing on the generating function of correlation functions and the application to the forced harmonic oscillator. The instructor explains the concept of coupling the system to an external source, providing examples from the lab and theory. The lecture delves into the idea of using functional methods in various systems, such as magnetic fields, spin systems, and carved geometries in quantum field theory. The discussion progresses to the solution of the forced harmonic oscillator, detailing the mathematical derivations and the significance of the results.