Week 7 prelecture assignment
Due: Monday, 27 February 2023, 2:15 PM
On week 7, the key topics are the Dyson equation and self-energy. These are extremely useful concepts in condensed matter quantum field theory, since they amount to resummations of infinite numbers of terms/diagrams.
On Monday we will consider the time-evolution of a many-body Green's function and see how the Feynman diagrams arise as a book-keeping tool from the Wick's theorem. On Wednesday we will generalize the discussion from Monday and introduce the Dyson equation. And on Thursday we will look at one important application of the self-energy formulation: the propagation of an electron in a system of random impurities.
This week's prelecture assignment involves three short videos in which Freeman Dyson is interviewed:
First one involves his experience with Feynman and his methods (3 minutes):
The second one his interaction with Schwinger (5 minutes):
And the last one was about the synthesis of the Feynman's, Schwinger's and Tomonaga's approaches (7 minutes):
I hope many of the things Dyson mentioned in the videos already sound familiar to you. Do you have any questions? Are you familiar with Wick's theorem?